2024-03-28T22:48:37Zhttps:/www.ncbi.nlm.nih.gov/pmc/oai/oai.cgioai:pubmedcentral.nih.gov:309392001-04-23bmcpharpmc-open
Flow cytometry analysis of the effect of allopurinol and the dinitroaniline compound (Chloralin) on the viability and proliferation of Leishmania infantum promastigotes
Kamau, Sarah W
Nunez, Rafael
Grimm, Felix
BMC Pharmacol
Research Article
BACKGROUND: Leishmaniasis is a major parasitic disease in the tropical regions. However, Leishmania infantum has recently emerged as a very important cause of opportunistic infections for individuals positive for human immunodeficiency virus (HIV). However, there is a lack of in vitro tests for assessing the effect of anti-parasitic drugs on the viability and proliferation of Leishmania infantum. The aim of this study is to assess the efficacy of anti-parasitic drugs like allopurinol and Chloralin on the viability and proliferation of L. infantum promastigotes by utilizing two complementary flow cytometric approaches after exposure of the promastigotes to various concentrations of the drugs. RESULTS: The density of the cultures in the presence and absence of allopurinol was determined by haemocytometer enumeration. The two flow cytometric approaches used to monitor the drug effect were: (i) a quantitative method to measure cell division using 5-,6-carboxyfluorescein diacetate succinimidyl ester (CFSE) staining and (ii) evaluation of cell viability by dual-staining with the membrane-permeable nuclear stain, SBRY-14 and propidium iodide. It was found that concentrations of allopurinol above 50 μg/ml yielded a clear decrease in the proliferation rate of the promastigotes. However, the viability results showed that about 46.8% of the promastigotes incubated in the presence of 800 μg/ml of allopurinol were still alive after 96 hours. In sharp contrast, more than 90% of promastigotes treated with Chloralin 10 μM (2.7 μg/ml) were dead after 48 hours of treatment. These flow cytometric findings suggest that allopurinol has a leishmaniostatic effect while the dinitroaniline compound (Chloralin) has a leishmaniocidal effect against promastigotes. CONCLUSIONS: The flow cytometric data on proliferation and viability were consistent with results obtained from haemocytometer counts and allowed us to develop a model for assessing in vitro the effects of medicaments like allopurinol and chloralin on L. infantum promastigotes on a cellular level.
BioMed Central
2001-04-05
/pmc/articles/PMC30939/
/pubmed/11299045
http://dx.doi.org/10.1186/1471-2210-1-1
Text
en
Copyright © 2001 Kamau et al; licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.
oai:pubmedcentral.nih.gov:481472001-09-04bmcpharpmc-open
The effect of GABA receptor ligands in experimental spina bifida occulta
Briner, Wayne
BMC Pharmacol
Research Article
BACKGROUND: The pathophysiology behind spina bifida and other neural tube defects (NTDs) is unclear. Folic acid is one variable, but other factors remain. Studies suggest that substances active at the GABA receptor may produce NTDs. To test this hypothesis pregnant rats were exposed to either the GABA a agonist muscimol (1, 2 or 4 mg/kg), the GABA a antagonist bicuculline (.5, 1, or 2 mg/kg), the GABA b agonist baclofen (15, 30, 60 mg/kg), or the GABA b antagonist hydroxysaclofen (1, 3, or 5 mg/kg) during neural tube formation. Normal saline was used as a control and valproic acid (600 mg/kg) as a positive control. The embryos were analyzed for the presence of a spina bifida like NTD. RESULTS: After drug administration the pregnancies were allowed to proceed to the 21(st) day of gestation. Then embryos were removed and skeletons staining and cleared. Vertebral arch closure was measured. Results indicate that the GABAa receptor agonist muscimol, the GABAa receptor antagonist bicuculline, and the GABAb agonist baclofen produced NTDs characterized by widening of the vertebral arch. Oppositely the GABAb antagonist hydroxysaclofen produced narrowing of the vertebral arches. CONCLUSIONS: The findings indicate that GABA a or b ligands are capable of altering neural formation. GABA may play a greater than appreciated role in neural tube formation and may be important in NTDs. The narrowing of the vertebral arch produced by the GABA b antagonist hydroxysalcofen suggests that GABA b receptor may play an undefined role in neural tube closure that differs from the GABA a receptor.
BioMed Central
2001-08-15
/pmc/articles/PMC48147/
/pubmed/11532198
http://dx.doi.org/10.1186/1471-2210-1-2
Text
en
Copyright © 2001 Briner; licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.
oai:pubmedcentral.nih.gov:556932001-09-18bmcpharpmc-open
Phorbol ester impairs electrical excitation of rat pancreatic beta-cells through PKC-independent activation of K(ATP) channels
Suga, Sechiko
Wu, Jie
Ogawa, Yoshiji
Takeo, Teruko
Kanno, Takahiro
Wakui, Makoto
BMC Pharmacol
Research Article
BACKGROUND: Phorbol 12-myristate 13-acetate (PMA) is often used as an activating phorbol ester of protein kinase C (PKC) to investigate the roles of the kinase in cellular functions. Accumulating lines of evidence indicate that in addition to activating PKC, PMA also produces some regulatory effects in a PKC-independent manner. In this study, we investigated the non-PKC effects of PMA on electrical excitability of rat pancreatic β-cells by using patch-clamp techniques. RESULTS: In current-clamp recording, PMA (80 nM) reversibly inhibited 15 mM glucose-induced action potential spikes superimposed on a slow membrane depolarization and this inhibition can not be prevented by pre-treatment of the cell with a specific PKC inhibitor, bisindolylmaleimide (BIM, 1 μM). In the presence of a subthreshold concentration (5.5 mM) of glucose, PMA hyperpolarized β-cells in a concentration-dependent manner (0.8–240 nM), even in the presence of BIM. Based on cell-attached single channel recordings, PMA increased ATP-sensitive K(+) channel (K(ATP)) activity. Based on inside-out patch-clamp recordings, PMA had little effect on K(ATP) activity if no ATP was in the bath, while PMA restored K(ATP) activity that was suppressed by 10 μM ATP in the bath. In voltage-clamp recording, PMA enhanced tolbutamide-sensitive membrane currents elicited by repetitive ramp pulses from -90 to -50 mV in a concentration-dependent manner, and this potentiation could not be prevented by pre-treatment of cell with BIM. 4α-phorbol 12,13-didecanoate (4α-PDD), a non-PKC-activating phorbol ester, mimicked the effect of PMA on both current-clamp and voltage-clamp recording configurations. With either 5.5 or 16.6 mM glucose in the extracellular solution, PMA (80 nM) increased insulin secretion from rat islets. However, in islets pretreated with BIM (1 μM), PMA did not increase, but rather reduced insulin secretion. CONCLUSION: In rat pancreatic β-cells, PMA modulates insulin secretion through a mixed mechanism: increases insulin secretion by activation of PKC, and meanwhile decrease insulin secretion by impairing β-cell excitability in a PKC-independent manner. The enhancement of K(ATP) activity by reducing sensitivity of K(ATP) to ATP seems to underlie the PMA-induced impairment of β-cells electrical excitation in response to glucose stimulation.
BioMed Central
2001-08-16
/pmc/articles/PMC55693/
/pubmed/11560763
http://dx.doi.org/10.1186/1471-2210-1-3
Text
en
Copyright © 2001 Suga et al; licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.
oai:pubmedcentral.nih.gov:569022001-10-01bmcpharpmc-open
Antinociceptive and antiedematogenic properties and acute toxicity of Tabebuia avellanedae Lor. ex Griseb. inner bark aqueous extract
de Miranda, Fábio Guilherme Gonçalves
Vilar, Jeane Carvalho
Alves, Ivana Andréa Nunes
Cavalcanti, Sócrates Cabral de Holanda
Antoniolli, Ângelo Roberto
BMC Pharmacol
Research Article
BACKGROUND: Tabebuia avellanedae is a tree from the Bignoniaceae family. Commonly know as "pau d'arco" in Brazil, its inner bark is used as analgesic, anti-inflammatory, antineoplasic and diuretic at the Brazilian northeast. A validation of the plant usage has not been previously performed. RESULTS: Antinociceptive and antiedematogenic effects of Tabebuia avellanedae Lor. ex Griseb. inner bark were measured by nociceptive experimental models in mice. A rat paw edema test induced by carrageenan (1%) was also performed in rats to access the plant's antiedematogenic effect. The inner bark aqueous extract, administered via oral in three different concentration, namely 100, 200 and 400 mg/Kg, reduced the nociception produced by acetic acid (0.6% in water, i.p.) by 49.9%, 63.7% and 43.8%, respectively. The aqueous extract (200 and 400 mg/Kg, p.o.) reduced formalin (1%) effects only at the second phase of the experiment by 49.3% and 53.7%, respectively. Naloxone (5 mg/Kg, i.p.) was not able to revert the extract effect, however caffeine (10 mg/Kg, i.p.) reverted its effect by 19.8% at the second phase of the formalin test. The aqueous extract (200 mg/Kg, p.o.) inhibited edema by 12.9% when we used the rat paw edema model. The acute toxicity was low in mice. CONCLUSION: The T. avellanedae inner bark aqueous extract presented antinociceptive and antiedematogenic activities at the used models, with a possible antinociceptive effect associated to the adenosine system.
BioMed Central
2001-09-13
/pmc/articles/PMC56902/
/pubmed/11574048
http://dx.doi.org/10.1186/1471-2210-1-6
Text
en
Copyright © 2001 de Miranda et al; licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.
oai:pubmedcentral.nih.gov:570012001-10-02bmcpharpmc-open
Effects of two atypical neuroleptics, olanzapine and risperidone, on the function of the urinary bladder and the external urethral sphincter in anesthetized rats
Vera, Pedro L
Miranda-Sousa, Alejandro
Nadelhaft, Irving
BMC Pharmacol
Research Article
BACKGROUND: A previous report showed that the atypical neuroleptic clozapine resulted in marked changes in urodynamic parameters and greatly inhibited the activity of the external urethral sphincter in anesthetized rats. Such findings may help explain the high incidence of urinary disturbances reported during clozapine therapy. In an effort to extend our observations to other atypical neuroleptic agents, the present study investigated the effects of two newer atypical antipsychotics, olanzapine and risperidone, on the bladder and external urethral sphincter during cystometry in anesthetized rats. RESULTS: At a dose of 0.1 mg/kg (i.v.), olanzapine decreased the micturition volume and increased the residual volume. In addition, olanzapine decreased the expulsion time and the amplitude of the high frequency oscillations observed during the expulsion phase. Larger doses (1 mg/kg) had a greater effect. Olanzapine also reduced the activity recorded from the external urethral sphincter, and the bursting observed during the expulsion phase was abolished by 1.0 mg/kg. Risperidone had similar effects although the maximal effects were smaller than those observed with olanzapine. The amplitude of bladder contractions elicited by electrical stimulation of the pelvic nerve was reduced by olanzapine but not risperidone suggesting a possible anti-muscarinic peripheral effect of olanzapine. CONCLUSIONS: Olanzapine and risperidone significantly altered several voiding parameters and decreased the activity of the external urethral sphincter in the anesthetized rat. We propose that these effects are due to the central action of these drugs and not to peripheral effects. These findings may explain some of the clinical reports of urinary incontinence with risperidone and may predict similar occurrences with olanzapine therapy.
BioMed Central
2001-08-31
/pmc/articles/PMC57001/
/pubmed/11580866
http://dx.doi.org/10.1186/1471-2210-1-4
Text
en
Copyright © 2001 Vera et al; licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.
oai:pubmedcentral.nih.gov:577522001-10-10bmcpharpmc-open
Omapatrilat normalizes renal function curve in spontaneously hypertensive rats
Morazo, Paloma
Fortepiani, Lourdes A
Clara Ortíz, M
Atucha, Noemí M
García-Estañ, Joaquín
BMC Pharmacol
Research Article
BACKGROUND: The present study was designed to analyze the chronic renal response to omapatrilat, a new vasopeptidase inhibitor, in spontaneously hypertensive rats (SHR). To that end, the renal and blood pressure response to a 4-day salt loading protocol was analyzed and the respective chronic renal curves constructed. RESULTS: In non treated animals, and under normal sodium intake (around 2 mEq/day), mean arterial pressure (MAP), was significantly higher in the SHR as compared with the controls (WKY). After increasing salt intake (8 times normal), MAP did not change significantly in any group and the animals reached a normal sodium balance in four days. In a second group of animals, omapatrilat was given orally for 15 days at the dose of 40 mg/kg/day in the drinking water. In these omapatrilat-treated animals, and under normal sodium intake, MAP was significantly lower in both groups, although the antihypertensive effect was much greater in the SHR, so that the MAP of the SHR group was completely normalized and similar to the WKY-treated group. The subsequent elevation of sodium intake did not significantly elevate MAP in any group and the animals could manage the sodium excess as well as the non treated groups. CONCLUSIONS: These results indicate that chronic treatment with omapatrilat normalizes blood pressure in SHR without affecting adversely the renal ability to eliminate a sodium load. Chronic treatment with omapatrilat resets the chronic pressure natriuresis relationship of the SHR to a normal level, thus without altering the normal salt-independence of this arterial hypertension model.
BioMed Central
2001-09-11
/pmc/articles/PMC57752/
/pubmed/11592920
http://dx.doi.org/10.1186/1471-2210-1-5
Text
en
Copyright © 2001 Morazo et al; licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.
oai:pubmedcentral.nih.gov:585862001-10-23bmcpharpmc-open
Inability of Serotonin to Activate the c-Jun N-terminal Kinase and p38 Kinase Pathways in Rat Aortic Vascular Smooth Muscle Cells
Banes, Amy KL
Loberg, Robert D
Brosius, Frank C
Watts, Stephanie W
BMC Pharmacol
Research Article
BACKGROUND: Serotonin (5-HT, 5-hydroxytryptamine) activates the Extracellular Signal-Regulated Kinase (ERK)/ Mitogen-Activated Protein Kinase (MAPK) pathways, in vascular smooth muscle cells. Parallel MAPK pathways, the c-Jun N-terminal Kinase (JNK) and p38 pathway, are activated by stimulators of the ERK/MAPK pathway. We hypothesized that 5-HT would activate the JNK and p38 pathways in rat vascular smooth muscle cells. RESULTS: Results were determined using standard Western analysis and phosphospecific JNK and p38 antibodies. No significant activation by 5-HT (10(-9) – 10(-5) M; 30 min) of the JNK or p38 pathways, as measured by protein phosphorylation, was observed in any of these experiments. These experiments were repeated in the presence of the serine/threonine phosphatase inhibitor okadaic acid (1 uM) and the tyrosine phosphatase inhibitor sodium orthovanadate (1 uM) to maximize any observable signal. Even under these optimized conditions, no activation of the JNK or p38 pathways by 5-HT was observed. Time course experiments (5-HT 10(-5) M; 5 min, 15 min, 30 min and 60 min) showed no significant activation of JNK after incubation with 5-HT at any time point. However, we detected strong activation of JNK p54 and p46 (5- and 7 fold increases in bands p54 and p46, respectively over control levels) by anisomycin (500 ng/ml, 30 min). Similarly, a JNK activity assay failed to reveal activation of JNK by 5-HT, in contrast to the strong stimulation by anisomycin. CONCLUSION: Collectively, these data support the conclusion that 5-HT does not activate the JNK or p38 pathways in rat vascular smooth muscle cells.
BioMed Central
2001-10-08
/pmc/articles/PMC58586/
/pubmed/11667949
http://dx.doi.org/10.1186/1471-2210-1-8
Text
en
Copyright © 2001 Banes et al; licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.
oai:pubmedcentral.nih.gov:595072001-11-02bmcpharpmc-open
Effect of a short-term in vitro exposure to the marine toxin domoic acid on viability, tumor necrosis factor-alpha, matrix metalloproteinase-9 and superoxide anion release by rat neonatal microglia
Mayer, Alejandro MS
Hall, Mary
Fay, Michael J
Lamar, Peter
Pearson, Celeste
Prozialeck, Walter C
Lehmann, Virginia KB
Jacobson, Peer B
Romanic, Anne M
Uz, Tolga
Manev, Hari
BMC Pharmacol
Research Article
BACKGROUND: The excitatory amino acid domoic acid, a glutamate and kainic acid analog, is the causative agent of amnesic shellfish poisoning in humans. No studies to our knowledge have investigated the potential contribution to short-term neurotoxicity of the brain microglia, a cell type that constitutes circa 10% of the total glial population in the brain. We tested the hypothesis that a short-term in vitro exposure to domoic acid, might lead to the activation of rat neonatal microglia and the concomitant release of the putative neurotoxic mediators tumor necrosis factor-α (TNF-α), matrix metalloproteinases-2 and-9 (MMP-2 and -9) and superoxide anion (O(2)-). RESULTS: In vitro, domoic acid [10 μM-1 mM] was significantly neurotoxic to primary cerebellar granule neurons. Although neonatal rat microglia expressed ionotropic glutamate GluR4 receptors, exposure during 6 hours to domoic acid [10 μM-1 mM] had no significant effect on viability. By four hours, LPS (10 ng/mL) stimulated an increase in TNF-α mRNA and a 2,233 % increase in TNF-α protein In contrast, domoic acid (1 mM) induced a slight rise in TNF-α expression and a 53 % increase (p < 0.01) of immunoreactive TNF-α protein. Furthermore, though less potent than LPS, a 4-hour treatment with domoic acid (1 mM) yielded a 757% (p < 0.01) increase in MMP-9 release, but had no effect on MMP-2. Finally, while PMA (phorbol 12-myristate 13-acetate) stimulated O(2)- generation was elevated in 6 hour LPS-primed microglia, a similar pretreatment with domoic acid (1 mM) did not prime O(2)- release. CONCLUSIONS: To our knowledge this is the first experimental evidence that domoic acid, at in vitro concentrations that are toxic to neuronal cells, can trigger a release of statistically significant amounts of TNF-α and MMP-9 by brain microglia. These observations are of considerable pathophysiological significance because domoic acid activates rat microglia several days after in vivo administration.
BioMed Central
2001-10-02
/pmc/articles/PMC59507/
/pubmed/11686853
http://dx.doi.org/10.1186/1471-2210-1-7
Text
en
Copyright © 2001 Mayer et al; licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.
oai:pubmedcentral.nih.gov:606492001-12-09bmcpharpmc-open
Receptorphin: A conserved peptide derived from the sequence of the opioid receptor, with opioid displacement activity and potent antiproliferative actions in tumor cells
Kampa, Marilena
Loukas, Spyros
Tsapis, Andreas
Castanas, Elias
BMC Pharmacol
Research Article
BACKGROUND: In addition to endogenous opioids, a number of peptide sequences, derived from endogenous (hemorphins, alphaS1-casomorphin), and exogenous proteins (casomorphins, exorphins) have been reported, possessing opioid activity. In the present work, we report the identification of a new peptide, receptorphin (Tyr-Ile-Phe-Asn-Leu), derived from the sequence of the second transmembrane loop of the opioid receptor. This sequence is unique for the opioid receptor, and conserved in all species and receptor-types. RESULTS AND DISCUSSION: Receptorphin competes for opioid binding, presenting a kappa-receptor interaction, while it binds equally to delta- and mu- opioid and somatostatin-binding sites, and inhibits the cell proliferation of a number of human cancer cell lines, in a dose-dependent and reversible manner, at the picomolar or the nanomolar range. Receptorphin shows a preferential action on prostate cancer cells. CONCLUSION: Our work identifies, for the first time a peptide, in a receptor sequence, possessing ligand-agonistic activities. A hypothesis, based on receptorphin liberation after cell death, is presented, which could tentatively explain the time-lag observed during opioid antiproliferative action.
BioMed Central
2001-11-27
/pmc/articles/PMC60649/
/pubmed/11737867
http://dx.doi.org/10.1186/1471-2210-1-9
Text
en
Copyright © 2001 Kampa et al; licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.
oai:pubmedcentral.nih.gov:606502001-12-09bmcpharpmc-open
Peroxisome proliferator-activated receptor agonists prevent 25-OH-cholesterol induced c-jun activation and cell death
Chang, Jason Y
Liu, Ling-Zhi
BMC Pharmacol
Research Article
BACKGROUND: Cholesterol oxides, the oxygenated derivatives of cholesterol, have been shown to cause programmed cell death in a variety of cell types. Using N9 microglia, this study was designed to investigate the molecular events induced by cholesterol oxides prior to the execution of programmed cell death. RESULTS: Microglia were very sensitive to 25-OH-cholesterol, such that a 2-day treatment of the cells with 5 μM 25-OH-cholesterol reduced cell viability to 5–10% of controls. There was a dose- and time-dependent increase in c-jun and phospho-c-jun levels in microglia prior to this 25-OH-cholesterol induced cell death. In contrast, 7-β-OH-cholesterol, which was relatively non-toxic to microglia, did not increase phospho-c-jun levels. Peroxisome proliferator-activated receptors (PPARs) are a group of nuclear receptors that have important roles in atherogenesis. Results from this study indicate that PPAR agonists such as 15d-PGJ(2), indomethacin and WY14643 can attenuate cholesterol oxide induced c-jun activation and cell death in microglia. CONCLUSIONS: Peroxisome proliferator-activated receptor agonists may be useful in future development of pharmacological agents against cholesterol oxide induced cytotoxicity.
BioMed Central
2001-11-27
/pmc/articles/PMC60650/
/pubmed/11737865
http://dx.doi.org/10.1186/1471-2210-1-10
Text
en
Copyright © 2001 Chang and Liu; licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.
oai:pubmedcentral.nih.gov:609912001-12-17bmcpharpmc-open
Minipig cytochrome P450 3A, 2A and 2C enzymes have similar properties to human analogs
Soucek, Pavel
Zuber, Roman
Anzenbacherová, Eva
Anzenbacher, Pavel
Guengerich, F Peter
BMC Pharmacol
Research Article
BACKGROUND: The search for an optimal experimental model in pharmacology is recently focused on (mini)pigs as they seem not only to be an alternative source of cells and tissues for xenotherapy but also an alternative species for studies on drug metabolism in man due to similarities between (mini) pig and human drug metabolizing systems. The purpose of this work is to characterize minipig liver microsomal cytochromes P450 (CYPs) by comparing their N-terminal sequences with corresponding human orthologs. RESULTS: The microsomal CYPs exhibit similar activities to their human orthologous enzymes (CYP3A4, nifedipine oxidation; 2A6, coumarin 7-hydroxylation; 2D6, bufuralol 1'-hydroxylation; 2E1, p-nitrophenol hydroxylation; and 2C9, tolbutamide hydroxylation). Specific minipig CYP (2A, 2C and 3A) enzymes were partially purified and proteins identified by immunostaining (using antibodies against the respective human CYPs) were used for N-terminal amino acid sequencing. From comparisons, it can be concluded that the sequence of the first 20 amino acids at the N-terminus of minipig CYP2A is highly similar to human CYP2A6 (70% identity). The N-terminal sequence of CYP2C shared about 50% similarity with human 2C9. The results on the minipig liver microsomal CYP3A yielded identical data with those obtained for amino acid sequences of the pig CYP3A29 showing 60% identity with human CYP3A4. CONCLUSIONS: Thus, our results further support the view that minipigs may serve as model animals in pharmacological/toxicological studies with substrates of human CYP enzymes, namely, of the CYP3A and CYP2A forms.
BioMed Central
2001-12-05
/pmc/articles/PMC60991/
/pubmed/11737866
http://dx.doi.org/10.1186/1471-2210-1-11
Text
en
Copyright © 2001 Soucek et al; licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.
oai:pubmedcentral.nih.gov:646372002-01-23bmcpharpmc-open
NO-independent regulatory site of direct sGC stimulators like YC-1 and BAY 41-2272
Becker, Eva Maria
Alonso-Alija, Cristina
Apeler, Heiner
Gerzer, Rupert
Minuth, Torsten
Pleiβ, Ulrich
Schmidt, Peter
Schramm, Matthias
Schröder, Henning
Schroeder, Werner
Steinke, Wolfram
Straub, Alexander
Stasch, Johannes-Peter
BMC Pharmacol
Research Article
BACKGROUND: The most important receptor for nitic oxide is the soluble guanylate cyclase (sGC), a heme containing heterodimer. Recently, a pyrazolopyridine derivative BAY 41-2272, structurally related to YC-1, was identified stimulating soluble guanylate cyclase in an NO-independent manner, which results in vasodilatation and antiplatelet activity. The study described here addresses the identification of the NO-independent site on soluble guanylate cyclase. RESULTS: We developed a photoaffinity label ((3)H-meta-PAL) for the direct and NO-independent soluble guanylate cyclase (sGC) stimulator BAY 41-2272 by introducing an azido-group into the tritium labeled compound. The synthesized photoaffinitylabel directly stimulates the purified sGC and shows in combination with NO a synergistic effect on sGC activity. Irradiation with UV light of (3)H-meta-PAL together with the highly purified sGC leads to a covalent binding to the α(1)-subunit of the enzyme. This binding is blocked by unlabeled meta-PAL, YC-1 and BAY 41-2272. For further identification of the NO-independent regulatory site the (3)H-meta-PAL labeled sGC was fragmented by CNBr digest. The (3)H-meta-PAL binds to a CNBr fragment, consisting of the amino acids 236–290 of the α(1)-subunit. Determination of radioactivity of the single PTH-cycles from the sequencing of this CNBr fragment detected the cysteines 238 and 243 as binding residues of the (3)H-meta-PAL. CONCLUSIONS: Our data demonstrate that the region surrounding the cysteines 238 and 243 in the α(1)-subunit of the sGC could play an important role in regulation of sGC activity and could be the target of this new type of sGC stimulators.
BioMed Central
2001-12-28
/pmc/articles/PMC64637/
/pubmed/11801189
http://dx.doi.org/10.1186/1471-2210-1-13
Text
en
Copyright © 2001 Becker et al; licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.
oai:pubmedcentral.nih.gov:647862002-01-25bmcpharpmc-open
In vivo models of lung neutrophil activation. Comparison of mice and hamsters
Corteling, Randolph
Wyss, Daniel
Trifilieff, Alexandre
BMC Pharmacol
Methodology Article
BACKGROUND: Evidence suggests that both the migration and activation of neutrophils into the airway is of importance in pathological conditions such as pulmonary emphysema. In the present study, we describe in vivo models of lung neutrophil infiltration and activation in mice and hamsters. RESULTS: BALB/c and C57BL/6 mice were intranasally treated with lipopolysaccharide (0.3 mg/kg). Twenty-four hours after, animals were treated intranasally with N-Formyl-Met-Leu-Phe (0 to 5 mg/kg). Golden Syrian hamsters were treated intratracheally with 0.5 mg/kg of lipopolysaccharide. Twenty-four hours after, animals were treated intratracheally with 0.25 mg/kg of N-Formyl-Met-Leu-Phe. Both mice and hamster were sacrificed two hours after the N-Formyl-Met-Leu-Phe application. In both BALB/c and C57BL/6 mice, a neutrophil infiltration was observed after the sequential application of lipopolysaccharide and N-Formyl-Met-Leu-Phe. However, 5 times less neutrophil was found in C57BL/6 mice when compared to BALB/c mice. This was reflected in the neutrophil activation parameters measured (myeloperoxidase and elastase activities). Despite the presence of neutrophil and their activation status, no lung haemorrhage could be detected in both strains of mice. When compared with mice, the lung inflammation induced by the sequential application of lipopolysaccharide and N-Formyl-Met-Leu-Phe was much greater in the hamster. In parallel with this lung inflammation, a significant lung haemorrhage was also observed. CONCLUSIONS: Both mouse and hamster can be used for pharmacological studies of new drugs or other therapeutics agents that aimed to interfere with neutrophil activation. However, only the hamster model seems to be suitable for studying the haemorrhagic lung injury process.
BioMed Central
2002-01-10
/pmc/articles/PMC64786/
/pubmed/11806755
http://dx.doi.org/10.1186/1471-2210-2-1
Text
en
Copyright © 2002 Corteling et al; licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.
oai:pubmedcentral.nih.gov:655252002-02-14bmcpharpmc-open
Pharmacokinetics of artesunate after single oral administration to rats
Olliaro, Piero L
Nair, Naren K
Sathasivam, Kathir
Mansor, Sharif M
Navaratnam, Vis
BMC Pharmacol
Research Article
BACKGROUND: Artesunate is a commonly used antimalarial drug derived from artemisinin. It is rapidly converted to dihydroartemisinin. Little is known on this conversion in the GI tract and blood, and how this influences absorption. In order to study the absorption phase of the kinetics of artesunate following oral administration in rats, samples were collected at baseline, and then 0.5, 2, 5, 10, 15, 30, 45, 60 and 120 minutes after a single dose of 150 mg. RESULTS: Peak concentration of parent artesunate and dihydroartemisinin was achieved within 5 and 37.5 +/- 8.7 min, respectively of start of administration through gavage. The half lives of absorption were 2.73 +/- 0.85 and 12.49 +/- 2.49 min, respectively. CONCLUSIONS: These times were considerably shorter for artesunate than those found in studies which start sampling later. The profiles of parent compound and metabolite result from a complex equation dictated by the pH-dependent rates of hydroxylation of artesunate to dihydroartemisinin, the different rates at which either compounds are absorbed, and the catalytic hydroxylation by esterases. The rate of chemical oxidation of artesunate is pH dependent; this explains its rapid conversion to dihydroartemisinin in the stomach, as compared to its greater stability in other compartments at higher pH and in plasma. We propose that variable proportions of absorption take place in the stomach, and conclude that parent artesunate reaches an early peak within minutes of dosing, and that the early dihydroartemisinin levels result primarily from the absorption of the metabolite as such.
BioMed Central
2001-12-20
/pmc/articles/PMC65525/
/pubmed/11835690
http://dx.doi.org/10.1186/1471-2210-1-12
Text
en
Copyright © 2001 Olliaro et al; licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.
oai:pubmedcentral.nih.gov:656972002-02-28bmcpharpmc-open
Low molecular mass dinitrosyl nonheme-iron complexes up-regulate noradrenaline release in the rat tail artery
Kleschyov, Andrei L
Hubert, Gilles
Munzel, Thomas
Stoclet, Jean-Claude
Bucher, Bernard
BMC Pharmacol
Research Article
BACKGROUND: Dinitrosyl nonheme-iron complexes can appear in cells and tissues overproducing nitric oxide. It is believed that due to their chemical nature these species may be implicated in certain pathophysiological events. We studied the possible role of low molecular mass dinitrosyl iron complexes in the control of noradrenaline release in electrically stimulated rat tail artery. RESULTS: A model complex, dinitrosyl-iron-thiosulfate (at 1–10 μM) produced a concentration-dependent enhancement of electrical field stimulated [(3)H]noradrenaline release (up to 2 fold). At the same time, dinitrosyl-iron-thiosulfate inhibited neurogenic vasoconstriction, consistent with its nitric oxide donor properties. A specific inhibitor of cyclic GMP dependent protein kinase, Rp-8pCPT-cGMPS, partially inhibited the effect of dinitrosyl-iron-thiosulfate on neurogenic vasoconstriction, but not on [(3)H]noradrenaline release. Another model complex, dinitrosyl-iron-cysteine (at 3 μM) elicited similar responses as dinitrosyl-iron-thiosulfate. Conventional NO and NO+ donors such as sodium nitroprusside, S-nitroso-L-cysteine or S-nitroso-glutathione (at 10 μM) had no effect on [(3)H]noradrenaline release, though they potently decreased electrically-induced vasoconstriction. The "false complex", iron(II)-thiosulfate showed no activity. CONCLUSIONS: Low molecular mass iron dinitrosyl complexes can up-regulate the stimulation-evoked release of vascular [(3)H]noradrenaline, apparently independently of their NO donor properties. This finding may have important implications in inflammatory tissues.
BioMed Central
2002-02-08
/pmc/articles/PMC65697/
/pubmed/11872148
http://dx.doi.org/10.1186/1471-2210-2-3
Text
en
Copyright © 2002 Kleschyov et al; licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.
oai:pubmedcentral.nih.gov:656982002-02-28bmcpharpmc-open
4-(N,N-dipropylamino)benzaldehyde inhibits the oxidation of all-trans retinal to all-trans retinoic acid by ALDH1A1, but not the differentiation of HL-60 promyelocytic leukemia cells exposed to all-trans retinal
Russo, James
Barnes, Annette
Berger, Katie
Desgrosellier, Jay
Henderson, Jennifer
Kanters, Ana
Merkov, Lubo
BMC Pharmacol
Research Article
BACKGROUND: The signal transduction pathways mediated by retinoic acid play a critical role in the regulation of cell growth and differentiation during embryogenesis and hematopoiesis as well as in a variety of tumor cell lines in culture. Following the reports that two members of the superfamily of aldehyde dehydrogenase (ALDH) enzymes, ALDH1A1 and ALDH1A2, were capable of catalyzing the oxidation of all-trans retinal to all-trans retinoic acid with submicromolar K(m) values, we initiated an investigation of the ability of 4-(N,N-dipropylamino)benzaldehyde (DPAB) to inhibit the oxidation of retinal by purified mouse and human ALDH1A1. RESULTS: Our results show that DPAB potently inhibits retinal oxidation, with IC(50) values of 0.11 and 0.13 μM for purified mouse and human ALDH1A1, respectively. Since the HL-60 human myeloid leukemic cell line has been used extensively to study the retinoic acid induced differentiation of HL-60 cells to granulocytes, and ALDH1A1 activity had previously been reported in HL-60 cells, we investigated the ability of DPAB to block differentiation of HL-60 promyelocytic leukemia cells exposed to retinal in culture. In HL-60 cells coincubated with 1 μM retinal and 50 μM DPAB for 144 hours, cell differentiation was inhibited only 30%. Furthermore, the NAD-dependent oxidation of propanal or retinal was less than 0.05 nmoles NADH formed/min-10(7) cells in spectrophotometric assays using HL-60 cell extracts. CONCLUSION: Although ALDH1A1 may be the major catalytic activity for retinal oxidation in some retinoid-dependent mouse and Xenopus embryonic tissues and in adult human and mouse hematopoietic stem cells, another catalytic activity appears to synthesize the retinoic acid ligand necessary to stimulate the differentiation of HL-60 cells to end stage granulocytes.
BioMed Central
2002-02-12
/pmc/articles/PMC65698/
/pubmed/11872149
http://dx.doi.org/10.1186/1471-2210-2-4
Text
en
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oai:pubmedcentral.nih.gov:889762002-03-19bmcpharpmc-open
Delta Opioid activation of the Mitogen-activated protein kinase cascade does not require transphosphorylation of Receptor Tyrosine Kinases
Kramer, H Kenneth
Onoprishvili, Irma
Andria, Matthew L
Hanna, Kayane
Sheinkman, Karina
Haddad, Lisa B
Simon, Eric J
BMC Pharmacol
Research Article
BACKGROUND: In this study, we investigated the mechanism(s) by which delta opioids induce their potent activation of extracellular signal-regulated protein kinases (ERKs) in different cell lines expressing the cloned δ-opioid receptor (δ-OR). While it has been known for some time that OR stimulation leads to the phosphorylation of both ERK isoforms, the exact progression of events has remained elusive. RESULTS: Our results indicate that the transphosphorylation of an endogenous epidermal growth factor receptor (EGFR) in the human embryonic kidney (HEK-293) cell line does not occur when co-expressed δ-ORs are stimulated by the δ-opioid agonist, D-Ser-Leu-enkephalin-Thr (DSLET). Moreover, neither pre-incubation of cultures with the selective EGFR antagonist, AG1478, nor down-regulation of the EGFR to a point where EGF could no longer activate ERKs had an inhibitory effect on ERK activation by DSLET. These results appear to rule out any structural or catalytic role for the EGFR in the δ-opioid-mediated MAPK cascade. To confirm these results, we used C6 glioma cells, a cell line devoid of the EGFR. In δ-OR-expressing C6 glioma cells, opioids produce a robust phosphorylation of ERK 1 and 2, whereas EGF has no stimulatory effect. Furthermore, antagonists to the RTKs that are endogenously expressed in C6 glioma cells (insulin receptor (IR) and platelet-derived growth factor receptor (PDGFR)) were unable to reduce opioid-mediated ERK activation. CONCLUSION: Taken together, these data suggest that the transactivation of resident RTKs does not appear to be required for OR-mediated ERK phosphorylation and that the tyrosine-phosphorylated δ-OR, itself, is likely to act as its own signalling scaffold.
BioMed Central
2002-03-01
/pmc/articles/PMC88976/
/pubmed/11897012
http://dx.doi.org/10.1186/1471-2210-2-5
Text
en
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oai:pubmedcentral.nih.gov:1007852002-04-04bmcpharpmc-open
The farnesyl transferase inhibitor RPR-130401 does not alter radiation susceptibility in human tumor cells with a K-Ras mutation in spite of large changes in ploidy and lamin B distribution
Mégnin-Chanet, Frédérique
Lavelle, François
Favaudon, Vincent
BMC Pharmacol
Research Article
BACKGROUND: Growth inhibition by RPR-130401, a non-peptidomimetic farnesyltransferase inhibitor, was investigated without or with combined exposure to ionizing radiation in three human tumor cell lines (HCT-116, MiAPaCa-2 and A-549) bearing a point mutation in the K-Ras gene. RESULTS: RPR-130401 inhibited cell growth with an IC(50) of 50 nM (HCT-116), 120 nM (MiAPaCa-2) and 710 nM (A-549), with a poor incidence of apoptosis. The drug brought about G1 and S phase depletion together with arrest of cells in G2 phase and induced a significant accumulation of hyperploid cells showing active S phase DNA synthesis, with HCT-116 and A-549 cells being the most and least responsive, respectively. The drug also produced dramatic changes of the nuclear lamin B pattern, without lamin B cleavage and perturbation of the actin cytoskeleton. On the other hand, RPR-130401 elicited strictly additive interaction in combined treatment with ionizing radiation with regard to cell kill, altered cell cycle progression and induced hyperploidy. CONCLUSIONS: The data suggest that disruption of orderly progression through mitosis and cytokinesis, is a major outcome of drug action and that this effect proceeds from inhibition of lamin B farnesylation. It is anticipated from the strict additivity of RPR-130401 and radiation that neither induced radiation resistance nor acute or late complications of radiotherapy, should occur in combined treatment with RPR-130401.
BioMed Central
2002-02-06
/pmc/articles/PMC100785/
/pubmed/11929613
http://dx.doi.org/10.1186/1471-2210-2-2
Text
en
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oai:pubmedcentral.nih.gov:1007862002-04-04bmcpharpmc-open
Central effects of clozapine in regulating micturition in anesthetized rats
Vera, Pedro L
Miranda-Sousa, Alejandro J
Ordorica, Raul C
Nadelhaft, Irving
BMC Pharmacol
Research Article
BACKGROUND: We previously showed that systemic administration of the atypical neuroleptic clozapine in the rat altered a number of urodynamic variables and inhibited the external urethral sphincter. Since clozapine acts at several receptor types both at the periphery and the central nervous system, the site of action remained uncertain. Therefore, the purpose of this study was to determine the effects of central administration of clozapine on the bladder and the external urethral sphincter during cystometry and to examine differences in spinal versus supraspinal administration. We extended our observations by delivering clozapine centrally in anesthetized rats instrumented with either an intrathecal (L6-S1 spinal segment) or an intracerebroventricular (lateral ventricle) catheter. RESULTS: Clozapine decreased micturition volume and increased residual volume possibly by acting at a supraspinal site. Expulsion time and amplitude of the high frequency oscillations were reduced by clozapine possibly by acting at a spinal site. Bladder capacity was increased after central clozapine but probably due to a peripheral effect. Clozapine acting at spinal and supraspinal sites increased pressure threshold. Contraction time and peak pressure were not affected by clozapine. The EMG from the external urethral sphincter was also reduced following clozapine centrally and suggests a spinal and a supraspinal site of action. CONCLUSIONS: The results from the present study suggest that spinal and supraspinal central sites mediate clozapine's action in inhibiting expulsion parameters and the external urethral sphincter of the rat. Therefore, the reduction in the voiding efficiency observed after clozapine appears to be mediated by spinal and supraspinal sites.
BioMed Central
2002-03-07
/pmc/articles/PMC100786/
/pubmed/11884246
http://dx.doi.org/10.1186/1471-2210-2-6
Text
en
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oai:pubmedcentral.nih.gov:1013842002-04-11bmcpharpmc-open
Antinociceptive and anti-inflammatory effects of Crocus sativus L. stigma and petal extracts in mice
Hosseinzadeh, Hossein
Younesi, Hani M
BMC Pharmacol
Research Article
BACKGROUND: Crocus sativus L. (saffron) is used in folk medicine, for example as an antiedematogenic agent. We aimed to evaluate the antinociceptive and anti-inflammatory activity of saffron extracts in mice. RESULTS: We used aqueous and ethanolic maceration extracts of Crocus sativus L. stigma and petals. Antinociceptive activity was examined using the hot plate and writhing tests. The effect of extracts against acute inflammation was studied using xylene induced ear edema in mice. The activity of the extracts against chronic inflammation was assessed by formalin-induced edema in the rat paw. In the hot plate tests, intraperitoneal injection of both extracts showed no significant antinociceptive activity in mice. The extracts exhibited antinociceptive activity against acetic acid induced writhing. Naloxone partially blocked only the antinociceptive activity of the stigma aqueous extract. Only the stigma extracts showed weak to moderate effect against acute inflammation. In chronic inflammation, both aqueous and ethanolic stigma extracts, as well as ethanolic petal extract, exerted anti-inflammatory effects. CONCLUSIONS: We conclude that aqueous and ethanolic extracts of saffron stigma and petal have an antinociceptive effect, as well as acute and/or chronic anti-inflammatory activity.
BioMed Central
2002-03-15
/pmc/articles/PMC101384/
/pubmed/11914135
http://dx.doi.org/10.1186/1471-2210-2-7
Text
en
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oai:pubmedcentral.nih.gov:1036692002-05-02bmcpharpmc-open
Down-regulation of the alpha-2C adrenergic receptor: involvement of a serine/threonine motif in the third cytoplasmic loop
Deupree, Jean D
Borgeson, Claudia D
Bylund, David B
BMC Pharmacol
Research Article
BACKGROUND: The mechanisms by which alpha-2 adrenergic receptors are down-regulated following chronic exposure to agonist are not well understood. Interestingly, the human alpha-2C receptor does not down-regulate, whereas the opossum alpha-2C receptor does down-regulate. A comparison of the amino acid sequence of the third intracellular loop of these two receptors shows that the opossum alpha-2C receptor contains a potential G protein-coupled receptor kinase (GRK)phosphorylation motif (EESSTSE) with four hydroxyl residues, whereas the human alpha-2C receptor motif only contains two hydroxyl residues (DESSAAAAE). Because a similar acidic serine-rich motif (EESSSSD) in the human alpha-2 adrenergic receptor has been demonstrated to be phosphorylated by GRK and all four serines are required for desensitization of the receptor, we sought to determine whether the EESSTSE sequence was involved in the down-regulation of the alpha-2C adrenergic receptor. RESULTS: Site-directed mutagenesis was used to mutate the opossum alpha-2C receptor to SSVA and AAVA in place of the SSTS wild-type sequence. Down-regulation experiments on CHO cells transfected with the receptors demonstrated that neither of the mutated receptors down-regulated following 24 h exposure to norepinephrine, whereas the wild-type receptor down-regulated to 65 ± 10% of the control. CONCLUSIONS: These results indicate that a motif with four hydroxyl amino acid residues in an acidic environment is important for down-regulation of the opossum alpha-2C adrenergic receptor. Because these are potential GRK phosphorylation sites, we suggest that GRK phosphorylation may be involved in alpha-2C adrenergic receptor down-regulation.
BioMed Central
2002-04-02
/pmc/articles/PMC103669/
/pubmed/11926967
http://dx.doi.org/10.1186/1471-2210-2-9
Text
en
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oai:pubmedcentral.nih.gov:1078362002-05-09bmcpharpmc-open
An MCASE approach to the search of a cure for Parkinson's Disease.
Klopman, Gilles
Sedykh, Aleksandr
BMC Pharmacol
Research Article
BACKGROUND: Parkinson's disease is caused by a dopamine deficiency state in the fore brain area. Dopamine receptor agonists, MAO-B inhibitors, and N-Methyl-D-Aspartate (NMDA) receptor antagonists are known to have antiparkinson effect. Levodopa, a dopamine structural analog, is the best currently available medication for the treatment of Parkinsons disease. Unfortunately, it also induces side effects upon long administration time. Thus, multidrug therapy is often used, in which various adjuvants alleviate side effects of levodopa and enhance its antiparkinsonian action. RESULTS: Computer models have been created for three known antiparkinson mechanisms using the MCASE methodology. New drugs for Parkinsons disease can be designed on the basis of these models. We also speculate that the presence of biophores belonging to different groups can be beneficial and designed some potential drugs along this line. The proposed compounds bear pharmacophores of MAO-B inhibitors, dopamine agonists and NMDA antagonists, which could synergistically enhance their antiparkinson effect. CONCLUSIONS: The methodology could readily be expanded to other endpoints where drugs with multiple activity mechanisms would be desirable.
BioMed Central
2002-04-02
/pmc/articles/PMC107836/
/pubmed/11926966
http://dx.doi.org/10.1186/1471-2210-2-8
Text
en
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oai:pubmedcentral.nih.gov:1078372002-05-09bmcpharpmc-open
Activation of the peroxisome proliferator-activated receptor α protects against myocardial ischaemic injury and improves endothelial vasodilatation
Tabernero, Antonia
Schoonjans, Kristina
Jesel, Laurence
Carpusca, Irina
Auwerx, Johan
Andriantsitohaina, Ramaroson
BMC Pharmacol
Research Article
BACKGROUND: The peroxisome proliferator-activated receptor α (PPARα) plays an important role in the metabolism of lipoproteins and fatty acids, and seems to protect against the development of atherosclerosis. To evaluate the possible protective role of PPARα on cardiovascular function, the effect of the PPARα agonist, fenofibrate was assessed with respect to ischaemia/reperfusion injury and endothelial function in mice. RESULTS: Fenofibrate treatment reduces myocardial infarction size and improves post-ischaemic contractile dysfunction. Hearts from PPARα null mice exhibit increased susceptibility to ischaemic damages and were refractory to protection by fenofibrate treatment suggesting that the beneficial effects of fenofibrate were mediated via PPARα. Furthermore, fenofibrate improves endothelium- and nitric oxide-mediated vasodilatation in aorta and mesenteric vascular bed. A decreased inhibitory effect of reactive oxygen species in the vessel wall accounts for enhanced endothelial vasodilatation. However, the latter cannot be explained by an increase in nitric oxide synthase expression nor by an increase sensitivity of the arteries to nitric oxide. CONCLUSIONS: Altogether the present data suggest that fenofibrate exerts cardioprotective effect against ischaemia and improves nitric oxide-mediated response probably by enhancing antioxidant capacity of the vessel wall. These data underscore new therapeutic perspectives for PPARα agonists in ischaemic myocardial injury and in cardiovascular diseases associated with endothelial dysfunction.
BioMed Central
2002-04-09
/pmc/articles/PMC107837/
/pubmed/11940253
http://dx.doi.org/10.1186/1471-2210-2-10
Text
en
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oai:pubmedcentral.nih.gov:1132672002-05-23bmcpharpmc-open
Seed germination, phenology, and antiedematogenic activity of Peperomia pellucida (L.) H. B. K.
Arrigoni-Blank, Maria de Fátima
Oliveira, Ricardo Luiz Barros
Mendes, Sandra Santos
Silva, Paulo de Albuquerque
Antoniolli, Ângelo Roberto
Vilar, Jeane Carvalho
Cavalcanti, Sócrates Cabral de Holanda
Blank, Arie Fitzgerald
BMC Pharmacol
Research Article
BACKGROUND: Peperomia pellucida is popularly known as coraçãozinho in the Brazilian northeast and is used in the treatment of abscesses, furuncles, and conjunctivitis. Our work aimed to determine the term of the development stages and the species cycle in the four seasons of the year (complete development, beginning of bloom, complete bloom, and seed set), verifying the plant's therapeutic profile during the four distinct development phases in order to detect differences in its potency. Pharmacological tests were performed to observe the anti-inflammatory activity. RESULTS: Phenological observations were accessed for a 12 month-period, from the Brazilian summer of 1999/2000 to fall 2000. On average the plantules' emergence occurred 15 days after seeding. All plantules grew in a similar manner up to 25 days after transplantation in all seasons. Starting on the 25(th) day, we observed faster growth during spring, with plants reaching a height of about 60 cm after 100 days of transplantation, unlike other seasons, in which plants reached heights of 40, 40, and 35 cm during winter, summer, and fall, respectively. The P. pellucida aqueous extract showed significant anti-inflammatory activity during phenophases 1 and 2 of winter and spring. Depending on the plant's phenophase there was variation in the potency of edema inhibition. CONCLUSION: P. pellucida has a phenological cycle of approximately 100 days. It is recommended that the P. pellucida aqueous extract is used as an antiedematogenic only during phenophases 1 and 2 of winter and spring.
BioMed Central
2002-05-09
/pmc/articles/PMC113267/
/pubmed/12019026
http://dx.doi.org/10.1186/1471-2210-2-12
Text
en
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oai:pubmedcentral.nih.gov:1137482002-05-30bmcpharpmc-open
In vitro susceptibility to pentavalent antimony in Leishmania infantum strains is not modified during in vitro or in vivo passages but is modified after host treatment with meglumine antimoniate
Carrió, Jaume
Portús, Montserrat
BMC Pharmacol
Research Article
BACKGROUND: Leishmaniasis is a common parasitic disease in Southern Europe, caused by Leishmania infantum. The failures of current treatment with pentavalent antimonials are partially attributable to the emergence of antimony-resistant Leishmania strains. This study analyses the in vitro susceptibility to pentavalent antimony of intracellular amastigotes from a range of L. infantum strains, derived from the same infected animal, during in vitro and in vivo passages and after host treatment with meglumine antimoniate. RESULTS: Sb(V)-IC50 values for strains from two distinct isolates from the same host and one stock after two years of culture in NNN medium and posterior passage to hamster were similar (5.0 ± 0.2; 4.9 ± 0.2 and 4.4 ± 0.1 mgSb(V)/L, respectively). In contrast, a significant difference (P < 0.01, t test) was observed between the mean Sb(V)-IC50 values in the stocks obtained before and after treatment of hosts with meglumine antimoniate (4.7 ± 0.4 mgSb(V)/L vs. 7.7 ± 1.5 mgSb(V)/L). Drug-resistance after drug pressure in experimentally infected dogs increased over repeated drug administration (6.4 ± 0.5 mgSb(V)/L after first treatment vs. 8.6 ± 1.4 mgSb(V)/L after the second) (P < 0.01, t test). CONCLUSIONS: These results confirm previous observations on strains from Leishmania/HIV co-infected patients and indicate the effect of the increasing use of antimony derivatives for treatment of canine leishmaniasis in endemic areas on the emergence of Leishmania antimony-resistant strains.
BioMed Central
2002-05-02
/pmc/articles/PMC113748/
/pubmed/12019027
http://dx.doi.org/10.1186/1471-2210-2-11
Text
en
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oai:pubmedcentral.nih.gov:1137612002-05-30bmcpharpmc-open
Selective alteration of gene expression in response to natural and synthetic retinoids.
Brand, Céline
Ségard, Pascaline
Plouvier, Pascal
Formstecher, Pierre
Danzé, Pierre-Marie
Lefebvre, Philippe
BMC Pharmacol
Research Article
BACKGROUND: Retinoids are very potent inducers of cellular differentiation and apoptosis, and are efficient anti-tumoral agents. Synthetic retinoids are designed to restrict their toxicity and side effects, mostly by increasing their selectivity toward each isotype of retinoic acids receptors (RARα,β, γ and RXRα, β, γ). We however previously showed that retinoids displayed very different abilities to activate retinoid-inducible reporter genes, and that these differential properties were correlated to the ability of a given ligand to promote SRC-1 recruitment by DNA-bound RXR:RAR heterodimers. This suggested that gene-selective modulation could be achieved by structurally distinct retinoids. RESULTS: Using the differential display mRNA technique, we identified several genes on the basis of their differential induction by natural or synthetic retinoids in human cervix adenocarcinoma cells. Furthermore, this differential ability to regulate promoter activities was also observed in murine P19 cells for the RARβ2 and CRABPII gene, showing conclusively that retinoid structure has a dramatic impact on the regulation of endogenous genes. CONCLUSIONS: Our findings therefore show that some degree of selective induction or repression of gene expression may be achieved when using appropriately designed ligands for retinoic acid receptors, extending the concept of selective modulators from estrogen and peroxisome proliferator activated receptors to the class of retinoid receptors.
BioMed Central
2002-05-13
/pmc/articles/PMC113761/
/pubmed/12019025
http://dx.doi.org/10.1186/1471-2210-2-13
Text
en
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oai:pubmedcentral.nih.gov:1174382002-07-26bmcpharpmc-open
Cloning and expression of the rabbit prostaglandin EP2 receptor
Guan, Youfei
Stillman, Brett A
Zhang, Yahua
Schneider, André
Saito, Osamu
Davis, Linda S
Redha, Reyadh
Breyer, Richard M
Breyer, Matthew D
BMC Pharmacol
Research Article
BACKGROUND: Prostaglandin E(2) (PGE(2)) has multiple physiologic roles mediated by G protein coupled receptors designated E-prostanoid, or "EP" receptors. Evidence supports an important role for the EP(2) receptor in regulating fertility, vascular tone and renal function. RESULTS: The full-length rabbit EP(2) receptor cDNA was cloned. The encoded polypeptide contains 361 amino acid residues with seven hydrophobic domains. COS-1 cells expressing the cloned rabbit EP(2) exhibited specific [(3)H]PGE(2) binding with a K(d) of 19.1± 1.7 nM. [(3)H]PGE(2) was displaced by unlabeled ligands in the following order: PGE(2)>>PGD(2)=PGF(2α)=iloprost. Binding of [(3)H]PGE(2) was also displaced by EP receptor subtype selective agonists with a rank order of affinity consistent with the EP2 receptor (butaprost>AH13205>misoprostol>sulprostone). Butaprost free acid produced a concentration-dependent increase in cAMP accumulation in rabbit EP(2) transfected COS-1 cells with a half-maximal effective concentration of 480 nM. RNase protection assay revealed high expression in the ileum, spleen, and liver with lower expression in the kidney, lung, heart, uterus, adrenal gland and skeletal muscle. In situ hybridization localized EP(2) mRNA to the uterine endometrium, but showed no distinct localization in the kidney. EP2 mRNA expression along the nephron was determined by RT-PCR and its expression was present in glomeruli, MCD, tDL and CCD. In cultured cells EP2 receptor was not detected in collecting ducts but was detected in renal interstitial cells and vascular smooth muscle cells. EP2 mRNA was also detected in arteries, veins, and preglomerular vessels of the kidney. CONCLUSION: EP2 expression pattern is consistent with the known functional roles for cAMP coupled PGE(2) effects in reproductive and vascular tissues and renal interstitial cells. It remains uncertain whether it is also expressed in renal tubules.
BioMed Central
2002-06-27
/pmc/articles/PMC117438/
/pubmed/12097143
http://dx.doi.org/10.1186/1471-2210-2-14
Text
en
Copyright © 2002 Guan et al; licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.
oai:pubmedcentral.nih.gov:1177832002-08-13bmcpharpmc-open
Does lindane (gamma-hexachlorocyclohexane) increase the rapid delayed rectifier outward K(+) current (I(Kr)) in frog atrial myocytes?
Sauviat, Martin-Pierre
Colas, Anthony
Pages, Nicole
BMC Pharmacol
Research Article
BACKGROUND: The effects of lindane, a gamma-isomer of hexachlorocyclohexane, were studied on transmembrane potentials and currents of frog atrial heart muscle using intracellular microelectrodes and the whole cell voltage-clamp technique. RESULTS: Lindane (0.34 microM to 6.8 microM) dose-dependently shortened the action potential duration (APD). Under voltage-clamp conditions, lindane (1.7 microM) increased the amplitude of the outward current (I(out)) which developed in Ringer solution containing TTX (0.6 microM), Cd(2+) (1 mM) and TEA (10 mM). The lindane-increased I(out) was not sensitive to Sr(2+) (5 mM). It was blocked by subsequent addition of quinidine (0.5 mM) or E-4031 (1 microM). E-4031 lengthened the APD; it prevented or blocked the lindane-induced APD shortening. CONCLUSIONS: In conclusion, our data revealed that lindane increased the quinidine and E-4031-sensitive rapid delayed outward K(+) current which contributed to the AP repolarization in frog atrial muscle.
BioMed Central
2002-07-10
/pmc/articles/PMC117783/
/pubmed/12106504
http://dx.doi.org/10.1186/1471-2210-2-15
Text
en
Copyright © 2002 Sauviat et al; licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.
oai:pubmedcentral.nih.gov:1262622002-09-20bmcpharpmc-open
Chronic garlic administration protects rat heart against oxidative stress induced by ischemic reperfusion injury
Banerjee, Sanjay Kumar
Dinda, Amit Kumar
Manchanda, Subhash Chandra
Maulik, Subir Kumar
BMC Pharmacol
Research Article
BACKGROUND: Oxidative stress plays a major role in the biochemical and pathological changes associated with myocardial ischemic-reperfusion injury (IRI). The need to identify agents with a potential for preventing such damage has assumed great importance. Chronic oral administration of raw garlic has been previously reported to augment myocardial endogenous antioxidants. In the present study, the effect of chronic oral administration of raw garlic homogenate on oxidative stress induced by ischemic-reperfusion injury in isolated rat heart was investigated. RESULTS: Raw garlic homogenate (125, 250 and 500 mg/kg once daily for 30 days) was administered orally in Wistar albino rats. Thereafter, hearts were isolated and subjected to IRI (9 min. of global ischemia, followed by 12 min of reperfusion; perfusion with K-H buffer solution; 37°C, 60 mm Hg.). Significant myocyte injury and rise in myocardial TBARS along with reduction in myocardial SOD, catalase, GSH and GPx were observed following IRI. Depletion of myocardial endogenous antioxidants and rise in TBARS were significantly less in the garlic-treated rat hearts. Oxidative stress induced cellular damage as indicated by ultrastructural changes, like disruption of myofilament, Z-band architecture along with mitochondrial changes were significantly less. CONCLUSIONS: The study strongly suggests that chronic garlic administration prevents oxidative stress and associated ultrastructural changes, induced by myocardial ischemic-reperfusion injury.
BioMed Central
2002-08-16
/pmc/articles/PMC126262/
/pubmed/12182765
http://dx.doi.org/10.1186/1471-2210-2-16
Text
en
Copyright © 2002 Banerjee et al; licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.
oai:pubmedcentral.nih.gov:1288152002-10-23bmcpharpmc-open
Interaction of neuronal nitric oxide synthase with alpha(1)-adrenergic receptor subtypes in transfected HEK-293 cells
Pupo, Andre S
Minneman, Kenneth P
BMC Pharmacol
Research Article
BACKGROUND: The C-terminal four amino acids (GEEV) of human α(1A)-adrenergic receptors (ARs) have been reported to interact with the PDZ domain of neuronal nitric oxide synthase (nNOS) in a yeast two-hybrid system. The other two α(1)-AR subtypes have no sequence homology in this region, raising the possibility of subtype-specific protein-protein interactions. RESULTS: We used co-immunoprecipitation and functional approaches with epitope-tagged α(1)-ARs to examine this interaction and the importance of the C-terminal tail. Following co-transfection of HEK-293 cells with hexahistidine/Flag (HF)-tagged α(1A)-ARs and nNOS, membranes were solubilized and immunoprecipitated with anti-FLAG affinity resin or anti-nNOS antibodies. Immunoprecipitation of HFα(1A)-ARs resulted in co-immunoprecipitation of nNOS and vice versa, confirming that these proteins interact. However, nNOS also co-immunoprecipitated with HFα(1B)- and HFα(1D)-ARs, suggesting that the interaction is not specific to the α(1A) subtype. In addition, nNOS co-immunoprecipitated with each of the three HFα(1)-AR subtypes which had been C-terminally truncated, suggesting that this interaction does not require the C-tails; and with Flag-tagged β(1)- and β(2)-ARs. Treatment of PC12 cells expressing HFα(1A)-ARs with an inhibitor of nitric oxide formation did not alter norepinephrine-mediated activation of mitogen activated protein kinases, suggesting nNOS is not involved in this response. CONCLUSIONS: These results show that nNOS does interact with full-length α(1A)-ARs, but that this interaction is not subtype-specific and does not require the C-terminal tail, raising questions about its functional significance.
BioMed Central
2002-08-16
/pmc/articles/PMC128815/
/pubmed/12184796
http://dx.doi.org/10.1186/1471-2210-2-17
Text
en
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oai:pubmedcentral.nih.gov:1300252002-10-24bmcpharpmc-open
The enhancement of the hyperglycemic effect of S-nitrosoglutathione and S-nitroso-N-acetylpenicillamine by vitamin C in an animal model
McGrowder, Donovan
Ragoobirsingh, Dalip
Dasgupta, Tara
BMC Pharmacol
Research Article
BACKGROUND: S-nitrosoglutathione (GSNO) and S-nitroso-N-acetlypenicillamine (SNAP) are two of the most common sources of nitric oxide (NO) in the biomedical field. Vitamin C has been known to accelerate the decomposition of GSNO and SNAP increasing the release and availability of NO which is cytotoxic at non-physiological concentrations. The study investigates any potential detrimental effect of vitamin C and GSNO, vitamin C and SNAP on glucose metabolism in normotensive and normoglycemic dogs. RESULTS: The results showed that administration of vitamin C (50 mg/kg) and GSNO (35 mg/kg & 50 mg/kg), or vitamin C (50 mg/kg) and SNAP (10 mg/kg) to overnight fasted dogs resulted in significant elevation of the blood glucose levels, attaining maximum level at the 2.0 or 2.5 h time point postprandially. The elevated blood glucose levels were due to significant reduction in plasma insulin levels in the dogs treated with vitamin C and GSNO, or vitamin C and SNAP (P < 0.05). The decreased insulin response was associated with significant elevation of nitric oxide produced from GSNO and SNAP co-administered with vitamin C, as assessed by plasma nitrate/nitrite levels. CONCLUSIONS: The results indicate that enhanced NO release by vitamin C affects postprandial blood glucose and plasma insulin levels and the reduced glucose tolerance is mainly due to impaired insulin release. The clinical relevance of the findings of this study suggest that hypertensive diabetic patients treated with GSNO or SNAP, who are on vitamin C supplements may be more predisposed to further decrease in their glycemic control.
BioMed Central
2002-09-13
/pmc/articles/PMC130025/
/pubmed/12230634
http://dx.doi.org/10.1186/1471-2210-2-18
Text
en
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oai:pubmedcentral.nih.gov:1375942002-12-08bmcpharpmc-open
Toxic cocaine- and convulsant-induced modification of forced swimming behaviors and their interaction with ethanol: comparison with immobilization stress
Hayase, Tamaki
Yamamoto, Yoshiko
Yamamoto, Keiichi
BMC Pharmacol
Research Article
BACKGROUND: Swimming behaviors in the forced swimming test have been reported to be depressed by stressors. Since toxic convulsion-inducing drugs related to dopamine [cocaine (COC)], benzodiazepine [methyl 6,7-dimethoxy-4-ethyl-β-carboline-carboxylate (DMCM)], γ-aminobutyric acid (GABA) [bicuculline (BIC)], and glutamate [N-methyl-D-aspartate (NMDA)] receptors can function as stressors, the present study compared their effects on the forced swimming behaviors with the effects of immobilization stress (IM) in rats. Their interactions with ethanol (EtOH), the most frequently coabused drug with COC which also induces convulsions as withdrawal symptoms but interferes with the convulsions caused by other drugs, were also investigated. RESULTS: Similar to the IM (10 min) group, depressed swimming behaviors (attenuated time until immobility and activity counts) were observed in the BIC (5 mg/kg IP) and DMCM (10 mg/kg IP) groups at the 5 h time point, after which no toxic behavioral symptoms were observed. However, they were normalized to the control levels at the 12 h point, with or without EtOH (1.5 g/kg IP). In the COC (60 mg/kg IP) and NMDA (200 mg/kg IP) groups, the depression occurred late (12 h point), and was normalized by the EtOH cotreatment. At the 5 h point, the COC treatment enhanced the swimming behaviors above the control level. CONCLUSIONS: Although the physiological stress (IM), BIC, and DMCM also depressed the swimming behaviors, a delayed occurrence and EtOH-induced recovery of depressed swimming were observed only in the COC and NMDA groups. This might be correlated with the previously-reported delayed responses of DA and NMDA neurons rather than direct effects of the drugs, which could be suppressed by EtOH. Furthermore, the characteristic psychostimulant effects of COC seemed to be correlated with an early enhancement of swimming behaviors.
BioMed Central
2002-11-09
/pmc/articles/PMC137594/
/pubmed/12425723
http://dx.doi.org/10.1186/1471-2210-2-19
Text
en
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oai:pubmedcentral.nih.gov:1375952002-12-08bmcpharpmc-open
The spinal antinociceptive effects of cholinergic drugs in rats: receptor subtype specificity in different nociceptive tests
Lograsso, Michael
Nadeson, Ray
Goodchild, Colin S
BMC Pharmacol
Research Article
BACKGROUND: Several studies have shown that muscarinic cholinergic agonists cause antinociception in humans and animals when given by both spinal and non-spinal parenteral routes. It is uncertain which subtype of muscarinic receptor is involved in spinally mediated antinociceptive effects caused by these drugs. The cholinergic receptor agonists McN-A-343 (M(1 )selective; 3.89 to 389 nmol) and carbachol (non-selective; 0.029 to 29 nmol) were used in a rat acute pain model to investigate the involvement of M(1 )and non-M(1 )subtypes in spinally mediated antinociception. The drugs were injected intrathecally and results from experiments in which drug actions were carefully confined to the spinal cord were used to construct agonist dose response curves. RESULTS: McN-A-343 frequently diffused rostrally to the brain, away from the lumbosacral site of injection. Thus, in spite of its receptor subtype selectivity, McN-A-343 is a poor probe to use in attempting to identify receptor subtypes involved in spinal cord antinociceptive systems. However, in some experiments McN-A-343 caused spinally mediated antinociception assessed by the electrical current threshold test. Antinociception assessed by the tail flick latency test with intrathecal McN-A-343 was observed and found to involve supraspinal mechanisms. Carbachol caused spinally mediated antinociception assessed by both electrical current threshold and tail flick latency. CONCLUSIONS: The results suggest that M(1 )receptors are involved in spinally mediated antinociception revealed by electrical current threshold; other cholinergic receptors (non-M(1)) are involved in thermal antinociception at the spinal cord. This contrasts with previous work on spinally mediated cholinergic antinociception. These differences are believed to be due to difficulties in restricting the action of these drugs to the spinal cord.
BioMed Central
2002-11-19
/pmc/articles/PMC137595/
/pubmed/12441008
http://dx.doi.org/10.1186/1471-2210-2-20
Text
en
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oai:pubmedcentral.nih.gov:1400312003-01-18bmcpharpmc-open
Effects of Anethum graveolens L. seed extracts on experimental gastric irritation models in mice
Hosseinzadeh, Hossein
Karimi, Gholam_Reza
Ameri, Maryam
BMC Pharmacol
Research Article
BACKGROUND: As a folk remedy, Anethum graveolens seed (dill) is used for some gastrointestinal ailments. We aimed to evaluate aqueous and ethanolic extracts of anti-ulcer and acute toxicity effects of the Anethum graveolens in mice. RESULTS: Gastric mucosal lesions were induced by oral administration of HCl (1 N) and absolute ethanol in mice. The acidity and total acid content of gastric juice were measured in pylorus-ligated mice. LD(50 )values of the aqueous and ethanolic extracts were 3.04 g/kg, i.p., (1.5, 6.16) and 6.98 g/kg, i.p., (5.69, 8.56), respectively. The efficacy of high dose of extracts (p.o.) was similar to sucralfate. The acidity and total acid content were reduced by the orally or intraperitoneally administration of the extracts. CONCLUSIONS: The results suggest that A. graveolens seed extracts have significant mucosal protective and antisecretory effects of the gastric mucosa in mice.
BioMed Central
2002-12-19
/pmc/articles/PMC140031/
/pubmed/12493079
http://dx.doi.org/10.1186/1471-2210-2-21
Text
en
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oai:pubmedcentral.nih.gov:1400362003-01-20bmcpharpmc-open
Activity of opioid ligands in cells expressing cloned mu opioid receptors
Gharagozlou, Parham
Demirci, Hasan
David Clark, J
Lameh, Jelveh
BMC Pharmacol
Research Article
BACKGROUND: The aim of the present study was to describe the activity of a set of opioid drugs, including partial agonists, in a cell system expressing only mu opioid receptors. Receptor activation was assessed by measuring the inhibition of forskolin-stimulated cyclic adenosine mono phosphate (cAMP) production. Efficacies and potencies of these ligands were determined relative to the endogenous ligand β-endorphin and the common mu agonist, morphine. RESULTS: Among the ligands studied naltrexone, WIN 44,441 and SKF 10047, were classified as antagonists, while the remaining ligands were agonists. Agonist efficacy was assessed by determining the extent of inhibition of forskolin-stimulated cAMP production. The rank order of efficacy of the agonists was fentanyl = hydromorphone = β-endorphin > etorphine = lofentanil = butorphanol = morphine = nalbuphine = nalorphine > cyclazocine = dezocine = metazocine ≥ xorphanol. The rank order of potency of these ligands was different from that of their efficacies; etorphine > hydromorphone > dezocine > xorphanol = nalorphine = butorphanol = lofentanil > metazocine > nalbuphine > cyclazocine > fentanyl > morphine >>>> β-endorphin. CONCLUSION: These results elucidate the relative activities of a set of opioid ligands at mu opioid receptor and can serve as the initial step in a systematic study leading to understanding of the mode of action of opioid ligands at this receptor. Furthermore, these results can assist in understanding the physiological effect of many opioid ligands acting through mu opioid receptors.
BioMed Central
2003-01-04
/pmc/articles/PMC140036/
/pubmed/12513698
http://dx.doi.org/10.1186/1471-2210-3-1
Text
en
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oai:pubmedcentral.nih.gov:1535092003-04-19bmcpharpmc-open
The angiotensin II receptor type 2 agonist CGP 42112A stimulates NO production in the porcine jejunal mucosa
Ewert, Sara
Laesser, Mats
Johansson, Bernalt
Holm, Mathias
Aneman, Anders
Fandriks, Lars
BMC Pharmacol
Research Article
BACKGROUND: This study was conducted to elucidate if nitric oxide is released by the porcine jejunal mucosa upon selective stimulation of AT2 receptors and the possible involvement of iNOS, and to investigate the presence of jejunal AT1 and AT2 receptors. Young landrace pigs were anaesthetized with ketamine and α-chloralose. Jejunal luminal NO output was assessed by intraluminal tonometry and analysed by chemiluminescense. Western blot analysis quantified mucosal iNOS and detected AT1 and AT2 receptor protein expression. AT1 and AT2 receptor RNA expression was detected by rtPCR. RESULTS: Baseline luminal NO output correlated significantly to baseline mucosal iNOS-protein content. In animals treated with the AT2-receptor agonist CGP42112A (n = 11) luminal NO output increased significantly (at 0.1 micrograms kg(-1 )min(-1 )and 1.0 micrograms kg(-1 )min(-1)), but not in animals simultaneously treated with the AT2-receptor antagonist PD123319 (bolus 0.3 mgkg(-1), infusion 0.03 mg kg(-1 )h(-1)) (n = 7). No differences in iNOS protein expression were found between groups or before/after the administration of drugs. Western blot and rtPCR recognised expression of the AT1 and AT2 receptors in jejunal tissue. CONCLUSION: The results suggest that activation of AT2 receptors increases jejunal luminal NO output. This response was not due to an increase in the expression of the iNOS protein in the mucosa.
BioMed Central
2003-03-04
/pmc/articles/PMC153509/
/pubmed/12689346
http://dx.doi.org/10.1186/1471-2210-3-2
Text
en
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oai:pubmedcentral.nih.gov:1566362003-06-05bmcpharpmc-open
Anticonvulsant, sedative and muscle relaxant effects of carbenoxolone in mice
Hosseinzadeh, Hossein
Nassiri Asl, Marjan
BMC Pharmacol
Research Article
BACKGROUND: Carbenoxolone, as an antiulcer medicine, has some pharmacological properties such as: the inhibition of gap junctional (GJ) intercellular communication. In vitro studies have shown, carbenoxolone to abolish the generation of full or partial ectopic spike generation, by 4-aminopyridine, as well as spontaneous epileptiform activity in CA(3 )or CA1 regions of the rat hippocampal slices via closing GJ channels. Thus, we considered the possible anticonvulsant effects of carbenoxolone in animal seizure models. RESULTS: ED(50 )values of diazepam and carbenoxolone in the pentylenetetrazole model were 1.13 mg/kg and 283.3 mg/kg, respectively. In this model, carbenoxolone in doses of 200 and 300 mg/kg prolonged the onset time of seizure and decreased the duration of seizures. In the maximal electroshock model, carbenoxolone in a dose of 400 mg/kg decreased the duration of seizure producing protection against seizure but failing to protect against mortality in comparison with diazepam. In the potentiation of pentobarbitone sleep test, carbenoxolone significantly increased sleeping time and decreased latency in doses of 100, 200 and 300 mg/kg in mice dose dependently. In the traction test, carbenoxolone (400 mg/kg) showed muscle relaxant activity and in the accelerated rotarod test, carbenoxolone in doses of 200 and 300 mg/kg showed a decline in motor coordination. CONCLUSION: It can be concluded that carbenoxolone possesses anticonvulsant, muscle relaxant and hypnotic effects, which could contribute to the control of petit mal and grand mal seizures.
BioMed Central
2003-04-29
/pmc/articles/PMC156636/
/pubmed/12720572
http://dx.doi.org/10.1186/1471-2210-3-3
Text
en
Copyright © 2003 Hosseinzadeh and Nassiri Asl; licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.
oai:pubmedcentral.nih.gov:1566572003-06-05bmcpharpmc-open
Potent P2Y(6 )receptor mediated contractions in human cerebral arteries
Malmsjö, Malin
Hou, Mingyan
Pendergast, William
Erlinge, David
Edvinsson, Lars
BMC Pharmacol
Research Article
BACKGROUND: Extracellular nucleotides play an important role in the regulation of vascular tone and may be involved in cerebral vasospasm after subarachnoidal haemorrhage. This study was designed to characterise the contractile P2 receptors in endothelium-denuded human cerebral and omental arteries. The isometric tension of isolated vessel segments was recorded in vitro. P2 receptor mRNA expression was examined by RT-PCR. RESULTS: In human cerebral arteries, the selective P2Y(6 )receptor agonist, UDPβS was the most potent of all the agonists tested (pEC(50 )= 6.8 ± 0.7). The agonist potency; UDPβS > αβ-MeATP > UTPγS > ATPγS > ADPβS = 0, indicated the presence of contractile P2X(1 )P2Y(2), P2Y(4 )and P2Y(6), but not P2Y(1 )receptors, in human cerebral arteries. In human omental arteries, UDPβS was inactive. The agonist potency; αβ-MeATP > ATPγS = UTPγS > ADPβS = UDPβS = 0, indicated the presence of contractile P2X(1), and P2Y(2 )receptors, but not P2Y(1 )or P2Y(6 )receptors, in human omental arteries. RT-PCR analysis of endothelium-denuded human cerebral and omental arteries demonstrated P2X(1), P2Y(1), P2Y(2 )and P2Y(6 )receptor mRNA expression. There were no bands for the P2Y(4 )receptor mRNA in the omental arteries, while barely detectable in the cerebral arteries. CONCLUSIONS: P2Y(6 )receptors play a prominent role in mediating contraction of human cerebral arteries. Conversely, no such effect can be observed in human omental arteries and previous results confirm the absence of P2Y(6 )receptors in human coronary arteries. The P2Y(6 )receptor might be a suitable target for the treatment of cerebral vasospasm.
BioMed Central
2003-05-09
/pmc/articles/PMC156657/
/pubmed/12737633
http://dx.doi.org/10.1186/1471-2210-3-4
Text
en
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oai:pubmedcentral.nih.gov:1654332003-07-16bmcpharpmc-open
The stereospecificity of flobufen metabolism in isolated guinea pig hepatocytes
Kral, Radim
Skalova, Lenka
Szotakova, Barbora
Velik, Jakub
Schroterova, Ladislava
Babu, Yogeeta N
Wsol, Vladimir
BMC Pharmacol
Research Article
BACKGROUND: Flobufen (F) is an original nonsteroidal anti-inflammatory drug with one center of chirality. 4-Dihydroflobufen (DHF), compound with two chiral centers, is the main metabolite of F in microsomes and cytosol in all standard laboratory animals. This work describes the biotransformation of F enantiomers and DHF stereoisomers in isolated male guinea pig hepatocytes. Guinea pigs were chosen with respect to similarities in F metabolism as in Man found earlier. R-F, S-F, (2R;4S)-DHF, (2S;4R)-DHF, (2S;4S)-DHF and (2R;4R)-DHF, structurally very similar compounds, served as substrates in order to observe their interaction with enzymes. Stereospecificity of the respective enzymes was studied in vitro, using hepatocytes monolayer. Chiral HPLC using R,R-ULMO column as chiral stationary phase was used for detection and quantitation of metabolites. RESULTS: (2R;4S)-DHF and (2S;4S)-DHF were the principle stereoisomers detected after incubation with rac-F, R-F and S-F. The ratio of (2R;4S)-DHF/(2S;4S)-DHF ranged from 1.1 to 2.4 depending on the substrate used. (2R;4S)-DHF was the major stereoisomer found after incubation with (2S;4S)-DHF and (2R;4R)-DHF. (2S;4S)-DHF was the principle stereoisomer found after incubation with (2R;4S)-DHF and (2S;4R)-DHF. Besides DHF stereoisomers, other metabolites (M-17203, UM-1 and UM-2) were also detected after incubation of hepatocytes monolayer with F. Interestingly, these metabolites were not found in incubation of all F forms and DHF with fresh liver homogenate. CONCLUSIONS: Different activities and stereospecificities of the respective enzymes were observed for each substrate in primary culture of hepatocytes. Cell integrity is crucial for formation of secondary metabolites M-17203, UM-1 and UM-2.
BioMed Central
2003-06-05
/pmc/articles/PMC165433/
/pubmed/12791169
http://dx.doi.org/10.1186/1471-2210-3-5
Text
en
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oai:pubmedcentral.nih.gov:1654342003-07-16bmcpharpmc-open
Effects of nimesulide on kainate-induced in vitro oxidative damage in rat brain homogenates
Candelario-Jalil, Eduardo
Sonia León, Olga
BMC Pharmacol
Research Article
BACKGROUND: The cyclooxygenase-2 inhibitor nimesulide is able to reduce kainate-induced oxidative stress in vivo. Here we investigate if this effect is mediated by the direct antioxidant properties of nimesulide using a well-characterized in vitro model of kainate toxicity. RESULTS: Exposure of rat brain homogenates to kainate (12 mM) caused a significant (p < 0.01) increase in the concentrations of malondialdehyde and 4-hydroxy-alkenals and a significant (p < 0.01) decrease in sulfhydryl levels. High concentrations of nimesulide (0.6–1.6 mM) reduced the extent of lipid peroxidation and the decline in both total and non-protein sulfhydryl levels induced by kainate in a concentration-dependent manner. CONCLUSIONS: Our results suggest that the neuroprotective effects of nimesulide against kainate-induced oxidative stress in vivo are not mediated through its direct free radical scavenging ability because the concentrations at which nimesulide is able to reduce in vitro kainate excitotoxicity are excessively higher than those attained in plasma after therapeutic doses.
BioMed Central
2003-06-14
/pmc/articles/PMC165434/
/pubmed/12807536
http://dx.doi.org/10.1186/1471-2210-3-7
Text
en
Copyright © 2003 Candelario-Jalil and Sonia León; licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.
oai:pubmedcentral.nih.gov:1655802003-07-16bmcpharpmc-open
The protective effect of M40401, a superoxide dismutase mimetic, on post-ischemic brain damage in Mongolian gerbils
Mollace, Vincenzo
Iannone, Michelangelo
Muscoli, Carolina
Palma, Ernesto
Granato, Teresa
Modesti, Andrea
Nisticò, Robert
Rotiroti, Domenicantonio
Salvemini, Daniela
BMC Pharmacol
Research Article
BACKGROUND: Overproduction of free radical species has been shown to occur in brain tissues after ischemia-reperfusion injury. However, most of free radical scavengers known to antagonize oxidative damage (e.g. superoxide dismutase, catalase), are unable to protect against ischemia-reperfusion brain injury when given in vivo, an effect mainly due to their difficulty to gain access to brain tissues. Here we studied the effect of a low molecular weight superoxide dismutase mimetic (M40401) in brain damage subsequent to ischemia-reperfusion injury in Mongolian gerbils. RESULTS: In animals undergoing ischemia-reperfusion injury, neuropathological and ultrastructural changes were monitored for 1–7 days either in the presence or in the absence of M40401 after bilateral common carotid artery occlusion (BCCO). Administration of M40401 (1–40 mg/kg, given i.p. 1 h after BCCO) protected against post-ischemic, ultrastructural and neuropathological changes occurring within the hippocampal CA1 area. The protective effect of M40401 was associated with a significant reduction of the levels of malondialdehyde (MDA; a marker of lipid peroxidation) in ischemic brain tissues after ischemia-reperfusion. CONCLUSION: Taken together, these results demonstrate that M40401 provides protective effects when given early after the induction of ischemia-reperfusion of brain tissues and suggest the possible use of such compounds in the treatment of neurological dysfunction subsequent to cerebral flow disturbances.
BioMed Central
2003-06-16
/pmc/articles/PMC165580/
/pubmed/12809567
http://dx.doi.org/10.1186/1471-2210-3-8
Text
en
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oai:pubmedcentral.nih.gov:1661352003-07-26bmcpharpmc-open
In vitro antileishmanial effects of antibacterial diterpenes from two Ethiopian Premna species: P. schimperi and P. oligotricha
Habtemariam, Solomon
BMC Pharmacol
Research Article
BACKGROUND: Three antibacterial diterpenes: (5R,8R,9S,10R)-12-oxo-ent-3,13(16)-clerodien-15-oic acid (1), 16-hydroxy-clerod-3,13(14)-diene-15,16-olide (2) and ent-12-oxolabda-8,13(16)-dien-15-oic acid (3) were previously isolated form Premna schimperi and P. oligotricha. Since andrographolide and other structurally related diterpenes were shown to have antileishmanial activity, the aim of the present study was to assess the in vitro effect of premna diterpenes against Leishmania aethiopica; the causative agent of cutaneous leishmaniasis in Ethiopia. RESULTS: The diterpenes showed potent concentration-dependant suppressive effect on the viability of axenically cultured amastigotes of L. aethiopica. The clerodane diterpenes 1 and 2 were most active (LD(50 )values 1.08 and 4.12 μg/ml respectively) followed by andrographolide and 3. Compounds 1 and 2 appear to be over 20 and 10-times respectively more selective to leishmania amastigotes than the permissive host cell line, THP-1 cells or the promastigotes stage of the parasites. CONCLUSION: The clerodane diterpenes (1, 2) which were more potent and selective than labdanes (andrographolide and 3) are promising for further studies and/or development.
BioMed Central
2003-06-06
/pmc/articles/PMC166135/
/pubmed/12793911
http://dx.doi.org/10.1186/1471-2210-3-6
Text
en
Copyright © 2003 Habtemariam; licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.
oai:pubmedcentral.nih.gov:1838462003-08-27bmcpharpmc-open
Effect of thymol on kinetic properties of Ca and K currents in rat skeletal muscle
Szentandrássy, Norbert
Szentesi, Péter
Magyar, János
Nánási, Péter P
Csernoch, László
BMC Pharmacol
Research Article
BACKGROUND: Thymol is widely used as a general antiseptic and antioxidant compound in the medical practice and industry, and also as a stabilizer to several therapeutic agents, including halothane. Thus intoxication with thymol may occur in case of ingestion or improper anesthesia. In the present study, therefore, concentration-dependent effects of thymol (30–600 micro-grams) were studied on calcium and potassium currents in enzymatically isolated rat skeletal muscle fibers using the double vaseline gap voltage clamp technique. RESULTS: Thymol suppressed both Ca and K currents in a concentration-dependent manner, the EC(50 )values were 193 ± 26 and 93 ± 11 μM, with Hill coefficients of 2.52 ± 0.29 and 1.51 ± 0.18, respectively. Thymol had a biphasic effect on Ca current kinetics: time to peak current and the time constant for inactivation increased at lower (100–200 μM) but decreased below their control values at higher (600 μM) concentrations. Inactivation of K current was also significantly accelerated by thymol (200–300 μM). These effects of thymol developed rapidly and were partially reversible. In spite of the marked effects on the time-dependent properties, thymol caused no change in the current-voltage relationship of Ca and K peak currents. CONCLUSIONS: Present results revealed marked suppression of Ca and K currents in skeletal muscle, similar to results obtained previously in cardiac cells. Furthermore, it is possible that part of the suppressive effects of halothane on Ca and K currents, observed experimentally, may be attributed to the concomitant presence of thymol in the superfusate.
BioMed Central
2003-07-15
/pmc/articles/PMC183846/
/pubmed/12864924
http://dx.doi.org/10.1186/1471-2210-3-9
Text
en
Copyright © 2003 Szentandrássy et al; licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.
oai:pubmedcentral.nih.gov:1947222003-09-16bmcpharpmc-open
Phenelzine treatment increases transcription factor AP-2 levels in rat brain
Damberg, Mattias
Berggård, Cecilia
Oreland, Lars
BMC Pharmacol
Research Article
BACKGROUND: The elevations of noradrenaline (NA) and serotonin (5-HT) levels in response to acute serotonin reuptake inhibitor (SSRI) or tricyclic antidepressant (TCA) exposure are not consistent with the time course for the therapeutic action of these antidepressants. Thus, neuronal adaptations are needed for the therapeutic effect to arise. Transcription factor Activating Protein –2 (AP-2) is critical for mammalian neural gene expression. Several genes involved in brainstem CNS transmitter systems, especially the monoamines, have AP-2 binding sites in their regulatory regions. We have previously shown that treatment with citalopram and imipramin resulted in a decrease in AP-2α and AP-2β levels in rat brain. We have also reported an association between a specific genotype of AP-2β to personality traits, binge-eating disorder and platelet monoamine oxidase (MAO) activity. RESULTS: Subchronic administration (10 days) of phenelzine (PLZ) increased the levels of AP-2α, AP-2β and the DNA binding activity of AP-2 in nuclear extracts prepared from rat whole brain when compared with sham treated animals. CONCLUSION: These data suggest that AP-2 is not involved in the theraputic effect of antidepressants. Rather, the effects of antidepressants seen on the levels of AP-2 might be involved in the expression of side-effects during the lag-period.
BioMed Central
2003-08-28
/pmc/articles/PMC194722/
/pubmed/12943557
http://dx.doi.org/10.1186/1471-2210-3-10
Text
en
Copyright © 2003 Damberg et al; licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.
oai:pubmedcentral.nih.gov:1947252003-09-16bmcpharpmc-open
Pharmacogenetic heterogeneity of transgene expression in muscle and tumours
Lefesvre, Pierre
Attema, Joline
van Bekkum, Dirk
BMC Pharmacol
Research Article
BACKGROUND: Recombinant adenoviruses are employed to deliver a therapeutic transgene in the liver, muscle or tumour tissue. However, to rationalise this delivery approach, the factors of variation between individuals need to be identified. It is assumed that differences between inbred strains of laboratory animals are considered to reflect differences between patients. Previously we showed that transgene expression in the liver of different rat strains was dependent on the transcription efficiency of the transgene. In the present paper we investigated if transfection of muscle and tumour tissue were also subject to such variations. METHODS: Variation, in transgene expression, after intramuscular gene delivery was determined in different rodent strains and gene expression in tumours was investigated in different human and rodent cell lines as well as in subcutaneously implanted rodent tumours. The molecular mechanisms involved in transgene expression were dissected using an adenovirus encoding luciferase. The luciferase activity, the viral DNA copies and the luciferase transcripts were assessed in cultured cells as well as in the tissues. RESULTS: Large differences of luciferase activity, up to 2 logs, were observed between different rodent strains after intramuscular injection of Ad Luciferase. This inter-strain variation of transgene expression was due to a difference in transcription efficiency. The transgene expression level in tumour cell lines of different tissue origin could be explained largely by the difference of infectibility to the adenovirus. In contrast, the main step responsible for luciferase activity variation, between six human breast cancer cell lines with similar phenotype, was at the transcriptional level. CONCLUSION: Difference in transcriptional efficiency in muscles as observed between different inbred strains and between human breast cancer cell lines may be expected to occur between individual patients. This might have important consequences for clinical gene therapy. The variation between tumour types and tissues within a species are mainly at the levels of infectivity.
BioMed Central
2003-08-28
/pmc/articles/PMC194725/
/pubmed/12943556
http://dx.doi.org/10.1186/1471-2210-3-11
Text
en
Copyright © 2003 Lefesvre et al; licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.
oai:pubmedcentral.nih.gov:2010252003-09-30bmcpharpmc-open
Arterial expression of 5-HT(2B )and 5-HT(1B )receptors during development of DOCA-salt hypertension
Banes, Amy KL
Watts, Stephanie W
BMC Pharmacol
Research Article
BACKGROUND: 5-hydroxytryptamine (5-HT)(2B )and 5-HT(1B )receptors are upregulated in arteries from hypertensive DOCA-salt rats and directly by mineralocorticoids. We hypothesized that increased 5-HT(2B )and 5-HT(1B )receptor density and contractile function would precede increased blood pressure in DOCA-high salt rats. We performed DOCA-salt time course (days 1, 3, 5 and 7) studies using treatment groups of: DOCA-high salt, DOCA-low salt, Sham and Sham-high salt rats. RESULTS: In isolated-tissue baths, DOCA-high salt aorta contracted to the 5-HT(2B )receptor agonist BW723C86 on day 1; Sham aorta did not contract. The 5-HT(1B )receptor agonist CP93129 had no effect in arteries from any group. On days 3, 5 and 7 CP93129 and BW723C86 contracted DOCA-high salt and Sham-high salt aorta; Sham and DOCA-low salt aorta did not respond. Western analysis of DOCA-high salt aortic homogenates revealed increased 5-HT(2B )receptor levels by day 3; 5-HT(1B )receptor density was unchanged. Aortic homogenates from the other groups showed unchanged 5-HT(2B )and 5-HT(1B )receptor levels. CONCLUSION: These data suggest that functional changes of 5-HT(2B )but not 5-HT(1B )receptors may play a role in the development of DOCA-salt hypertension.
BioMed Central
2003-09-15
/pmc/articles/PMC201025/
/pubmed/12974983
http://dx.doi.org/10.1186/1471-2210-3-12
Text
en
Copyright © 2003 Banes and Watts; licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.
oai:pubmedcentral.nih.gov:2806532003-11-29bmcpharpmc-open
Mutational analysis of molecular requirements for the actions of general anaesthetics at the γ-aminobutyric acid(A )receptor subtype, α1β2γ2
Siegwart, Roberta
Krähenbühl, Karin
Lambert, Sachar
Rudolph, Uwe
BMC Pharmacol
Research Article
BACKGROUND: Amino acids in the β subunit contribute to the action of general anaesthetics on GABA(A )receptors. We have now characterized the phenotypic effect of two β subunit mutations in the most abundant GABA(A )receptor subtype, α1β2γ2. RESULTS: The β2(N265M) mutation in M2 decreased the modulatory actions of propofol, etomidate and enflurane, but not of alphaxalone, while the direct actions of propofol, etomidate and alphaxalone were impaired. The β2(M286W) mutation in M3 decreased the modulatory actions of propofol, etomidate and enflurane, but not of alphaxalone, whereas the direct action of propofol and etomidate, but not of alphaxalone, was impaired. CONCLUSIONS: We found that the actions of general anaesthetics at α1β2(N265M)γ2 and α1β2(M286W)γ2 GABA(A )receptors are similar to those previously observed at α2β3(N265M)γ2 and α2β3(M286W)γ2 GABA(A )recpetors, respectively, with the notable exceptions that the direct action of propofol was decreased in α1β2(M286W)γ2 receptors but indistinguishable form wild type in α2β3(M286W)γ2 receptors and that the direct action of alphaxalone was decreased in α1β2(N265M)γ2 but not α2β3(N265M)γ2 receptors and indistinguishable form wild type in α1β2(M286W)γ2 receptors but increased in α2β3(M286W)γ2 receptors. Thus, selected phenotypic consequences of these two mutations are GABA(A )receptor subtype-specific.
BioMed Central
2003-11-12
/pmc/articles/PMC280653/
/pubmed/14613517
http://dx.doi.org/10.1186/1471-2210-3-13
Text
en
Copyright © 2003 Siegwart et al; licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.
oai:pubmedcentral.nih.gov:3172942004-01-23bmcpharpmc-open
Enhanced spontaneous activity of the mu opioid receptor by cysteine mutations: characterization of a tool for inverse agonist screening.
Brillet, Karl
Kieffer, Brigitte L
Massotte, Dominique
BMC Pharmacol
Research Article
BACKGROUND: The concept of spontaneous- or constitutive-activity has become widely accepted and verified for numerous G protein-coupled receptors and this ligand-independent activity is also acknowledged to play a role in some pathologies. Constitutive activity has been reported for the mu opioid receptor. In some cases the increase in receptor basal activity was induced by chronic morphine administration suggesting that constitutive activity may contribute to the development of drug tolerance and dependence. Constitutively active mutants represent excellent tools for gathering information about the mechanisms of receptor activation and the possible physiological relevance of spontaneous receptor activity. The high basal level of activity of these mutants also allows for easier identification of inverse agonists, defined as ligands able to suppress spontaneous receptor activity, and leads to a better comprehension of their modulatory effects as well as possible in vivo use. RESULTS: Cysteines 348 and 353 of the human mu opioid receptor (hMOR) were mutated into alanines and Ala(348,353 )hMOR was stably expressed in HEK 293 cells. [(35)S] GTPγS binding experiments revealed that Ala(348,353 )hMOR basal activity was significantly higher when compared to hMOR, suggesting that the mutant receptor is constitutively active. [(35)S] GTPγS binding was decreased by cyprodime or CTOP indicating that both ligands have inverse agonist properties. All tested agonists exhibited binding affinities higher for Ala(348,353 )hMOR than for hMOR, with the exception of endogenous opioid peptides. Antagonist affinity remained virtually unchanged except for CTOP and cyprodime that bound the double mutant with higher affinities. The agonists DAMGO and morphine showed enhanced potency for the Ala(348,353 )hMOR receptor in [(35)S] GTPγS experiments. Finally, pretreatment with the antagonists naloxone, cyprodime or CTOP significantly increased Ala(348,353 )hMOR expression. CONCLUSION: Taken together our data indicate that the double C348/353A mutation results in a constitutively active conformation of hMOR that is still activated by agonists. This is the first report of a stable CAM of hMOR with the potential to screen for inverse agonists.
BioMed Central
2003-12-01
/pmc/articles/PMC317294/
/pubmed/14641935
http://dx.doi.org/10.1186/1471-2210-3-14
Text
en
Copyright © 2003 Brillet et al; licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.
oai:pubmedcentral.nih.gov:3172952004-01-23bmcpharpmc-open
Enhanced β(2)-adrenergic receptor (β(2)AR) signaling by adeno-associated viral (AAV)-mediated gene transfer
Jones, Stacie M
Hiller, F Charles
Jacobi, Sandie E
Foreman, Susan K
Pittman, Laura M
Cornett, Lawrence E
BMC Pharmacol
Research Article
BACKGROUND: β(2)-Adrenergic receptors (β(2)AR) play important regulatory roles in a variety of cells and organ systems and are important therapeutic targets in the treatment of airway and cardiovascular disease. Prolonged use of β-agonists results in tolerance secondary to receptor down-regulation resulting in reduced therapeutic efficiency. The purpose of this work is to evaluate the signaling capabilities of the β(2)AR expressed by a recombinant adeno-associated viral (AAV) vector that also included an enhanced green fluorescent protein (EGFP) gene (AAV-β(2)AR/EGFP). RESULTS: By epifluorescence microscopy, ~40% of infected HEK 293 cells demonstrated EGFP expression. β(2)AR density measured with [(3)H]dihydroalprenolol ([(3)H]DHA) increased either 13- or 77-fold in infected cells compared to mock infected controls depending on the culture conditions used. The [(3)H]DHA binding was to a single receptor population with a dissociation constant of 0.42 nM, as would be expected for wild-type β(2)AR. Agonist competition assays with [(3)H]DHA showed the following rank order of potency: isoproterenol>epinephrine> norepinephrine, consistent with β(2)AR interaction. Isoproterenol-stimulated cyclic AMP levels were 5-fold higher in infected cells compared to controls (314 ± 43 vs. 63.4 ± 9.6 nmol/dish; n = 3). Receptor trafficking demonstrated surface expression of β(2)AR with vehicle treatment and internalization following isoproterenol treatment. CONCLUSIONS: We conclude that HEK 293 cells infected with AAV-β(2)AR/EGFP effectively express β(2)AR and that increased expression of these receptors results in enhanced β(2)AR signaling. This method of gene transfer may provide an important means to enhance function in in vivo systems.
BioMed Central
2003-12-04
/pmc/articles/PMC317295/
/pubmed/14656380
http://dx.doi.org/10.1186/1471-2210-3-15
Text
en
Copyright © 2003 Jones et al; licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.
oai:pubmedcentral.nih.gov:3244012004-01-31bmcpharpmc-open
Protection against acute adriamycin-induced cardiotoxicity by garlic: Role of endogenous antioxidants and inhibition of TNF-α expression
Mukherjee, Sumanta
Banerjee, Sanjay Kumar
Maulik, Mohua
Dinda, Amit Kumar
Talwar, Kewal K
Maulik, Subir Kumar
BMC Pharmacol
Research Article
BACKGROUND: Oxidative stress is the major etiopathological factor in adriamycin-induced cardiotoxicity. Relatively low amounts of endogenous antioxidant makes the heart vulnerable to oxidative stress-induced damage. Chronic oral administration of garlic has been reported to enhance the endogenous antioxidants of heart. We hypothesized that garlic-induced enhanced cardiac antioxidants may offer protection against acute adriamycin-induced cardiotoxicity. RESULTS: Rats were either administered freshly prepared garlic homogenate (250 and 500 mg/kg daily, orally, for 30 days) or probucol (cumulative dose, 120 mg/kg body weight divided in 12, i.p. over a period of 30 days) or double distilled water (vehicle), followed by a single dose of adriamycin (30 mg/kg i.p.). In the adriamycin group, increased oxidative stress was evidenced by a significant increase in myocardial TBARS (thiobarbituric acid reactive substances) and decrease in myocardial SOD (superoxide dismutase), catalase and GPx (glutathione peroxidase) activity. Histopathological studies showed focal as well as subendocardial myocytolysis with infiltration of macrophages, lymphocytes and edema. Immunocytochemistry showed marked expression of TNF-α (tumor necrosis factor-alpha) in the myocardium. Increase in myocardial TBARS and decrease in endogenous antioxidants by adriamycin was prevented significantly in the garlic treated rat hearts, which was comparable to the probucol-treated group. Histopathological evidence of protection was also evident in both garlic-treated and probucol-treated groups. Probucol, 250 mg/kg and 500 mg/kg of garlic reduced adriamycin induced TNF-α expression in the myocardium and was associated with reduced myocyte injury. CONCLUSIONS: It is concluded that chronic garlic administration prevents acute adriamycin-induced cardiotoxicity and decreases myocardial TNF-α expression.
BioMed Central
2003-12-20
/pmc/articles/PMC324401/
/pubmed/14687418
http://dx.doi.org/10.1186/1471-2210-3-16
Text
en
Copyright © 2003 Mukherjee et al; licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.
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