Quantitative changes of nicotinic receptors in the hippocampus of dystrophin-deficient mice

Lack of dystrophin in Duchenne muscle dystrophy (DMD) and in the mutant mdx mouse results in progressive muscle degeneration, structural changes at the neuromuscular junction, and destabilization of the nicotinic acetylcholine receptors (nAChRs). One-third of DMD patients also present non-progressive cognitive impairments. Considering the role of the cholinergic system in cognitive functions, the number of nAChR binding sites and the mRNA levels of alpha 4, beta 2, and alpha 7 subunits were determined in brain regions normally enriched in dystrophin (cortex, hippocampus and cerebellum) of mdx mice using specific ligands and reverse-transcription polymerase chain reaction assays, respectively. Membrane preparations of these brain regions were obtained from male control and mdx mice at 4 and 12 months of age. the number of [H-3]-cytisine (alpha 4 beta 2) and [I-125]-alpha-bungarotoxin ([I-125]-alpha BGT, alpha 7) binding sites in the cortex and cerebellum was not altered with age or among age-matched control and mdx mice. A significant reduction in [H-3]-cytisine (48%) and [I-125]-alpha BGT (37%) binding sites was detected in the hippocampus of mdx mice at 12 months of age. When compared with the age-matched control groups, the mdx mice did not have significantly altered [H-3]-cytisine binding in the hippocampus, but [I-125]-alpha BGT binding in the same brain region was 52% higher at 4 months and 20% lower at 12 months. mRNA transcripts for the nAChR alpha 4, beta 2, and alpha 7 subunits were not significantly altered in the same brain regions of all animal groups. These results suggest a potential alteration of the nicotinic cholinergic function in the hippocampus of dystrophin-deficient mice, which might contribute to the impairments in cognitive functions, such as learning and memory, that have been reported in the dystrophic murine model and DMD patients. (C) 2012 Elsevier B.V. All rights reserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Universidade Federal de São Paulo, Escola Paulista Med, Sect Nat Prod, Dept Pharmacol, São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Sect Expt Endocrinol, Dept Pharmacol, São Paulo, BrazilUniv Fed Santa Catarina, Dept Pharmacol, Neuropharmacol Lab, Florianopolis, SC, BrazilAmazon Biotechnol Ctr, Lab Pharmacol & Toxicol, Manaus, AM, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Sect Nat Prod, Dept Pharmacol, São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Sect Expt Endocrinol, Dept Pharmacol, São Paulo, BrazilWeb of Scienc

Kinetic characterization of gyroxin, a serine protease from Crotalus durissus terrificus venom

This work describes for the first time the characterization of the enzymatic features of gyroxin, a serine protease from Crotalus durissus terrificus venom, capable to induce barrel rotation syndrome in rodents. Measuring the hydrolysis of the substrate ZFR-MCA, the optimal pH for proteolytic cleavage of gyroxin was found to be at pH 8.4. Increases in the hydrolytic activity were observed at temperatures from 25 degrees C to 45 degrees C, and increases of NaCl concentration up to 1 M led to activity decreases. the preference of gyroxin for Arg residues at the substrate P1 position was also demonstrated. Taken together, this work describes the characterization of substrate specificity of gyroxin, as well as the effects of salt and pH on its enzymatic activity. (C) 2012 Elsevier Masson SAS. All rights reserved.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Universidade Federal de São Paulo, Dept Farmacol, BR-04044020 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Biofis, BR-04044020 São Paulo, BrazilInst Ciencias Mar UFC, BR-60165081 Fortaleza, Ceara, BrazilUniv Estado Amazonas, Escola Super Ciencias Saude INCT, BR-69065001 Manaus, Amazonas, BrazilUniversidade Federal de São Paulo, Dept Farmacol, BR-04044020 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Biofis, BR-04044020 São Paulo, BrazilWeb of Scienc

Transmissao neuromuscular, propriedades eletricas da membrana e capacidade contratil do musculo esterno-radial do sapo (Bufo marinus, L.): estudo comparativo em machos, femeas e machos castrados

BV UNIFESP: Teses e dissertaçõe

VASOCONSTRICTION INDUCED BY DELTA-9-TETRAHYDROCANNABINOL ON THE PERFUSED RABBIT EAR ARTERY

ESCOLA PAULISTA MED,DEPT PHARMACOL,SAO PAULO 04023,SP,BRAZILESCOLA PAULISTA MED,DEPT PHARMACOL,SAO PAULO 04023,SP,BRAZILWeb of Scienc

A comparative study of two clerodane diterpenes from Baccharis trimera (Less.) DC. on the influx and mobilization of intracellular calcium in rat cardiomyocytes

Baccharis trimera (Less.) D.C. (Asteraceae) is a medicinal species native to South America and used in Brazilian folk medicine to treat gastrointestinal and liver diseases, kidney disorders and diabetes. the aqueous extract (AE) of the aerial parts of this species presented two mainly constituents: the ent-clerodane diterpene (Fig. 1) and the neo-clerodane diterpene (Fig. 2). the objective of this work was to study their activities on the blockade of Ca2+-induced contractions in KCL-depolarized rat portal vein preparations, and on the influx and mobilization of cytosolic calcium in rat cardiomyocytes by fluorescence measurements. the results showed that both the neo- and the ent-clerodane diterpenes reduced the maximal contractions induced by CaCl2, in KO depolarized rat portal vein preparations, without modifying the EC50. the data on the concentration of cytosolic calcium ([Ca2+](c)) showed that, while the neo-clerodane diterpene stimulates the mobilization of [Ca2+](c) in rat cardiomyocytes, this effect was not observed with the ent-clerodane diterpene. On the other hand, the influx of calcium was not altered by the neo-clerodane diterpene, but was reduced in the presence of the ent-clerodane diterpene, indicating that this compound induces a blockade of the voltage-dependent calcium channels. (C) 2014 Elsevier GmbH. All rights reserved.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fed Univ São Paulo UNIFESP, Dept Pharmacol, Sch Med, BR-04044020 São Paulo, BrazilInst Bot, São Paulo, BrazilFed Univ São Paulo UNIFESP, Dept Pharmacol, Sch Med, BR-04044020 São Paulo, BrazilWeb of Scienc

Antisecretory actions of Baccharis trimera (Less.) DC aqueous extract and isolated compounds: Analysis of underlying mechanisms

Ethnopharmacological relevance: Baccharis trimera (Less.) DC. (Asteraceae) is a species native to South America used in Brazilian folk medicine to treat gastrointestinal and liver diseases, kidney disorders and diabetes. Previous studies from this laboratory confirmed the antacid and antiulcer activities of the plant aqueous extract (AE) in rat and mouse models.Aim of the study: To investigate the mechanisms involved in the antacid action of AE and isolated compounds from Baccharis trimera.Materials and methods: AE was assayed in vivo in cold-restraint stress gastric ulcers and in pylorus-ligated mice. Nine fractions (F2-F10) previously isolated from AE were assayed in vitro on acid secretion measured as [(14)C]-aminopyrine ([(14)C]-AP) accumulation in rabbit gastric glands, and on gastric microsomal H(+), K(+)-ATPase preparations. Chlorogenic acids (F2, F3, F6, F7), flavonoids (F9), an ent-clerodane diterpene (F8) and a dilactonic neo-clerodane diterpene (F10) have been identified in these fractions.Results: Intraduodenal injection of AE (1.0 and 2.0 g/kg) in 4 h pylorus-ligated mice decreased the volume (20 and 50%) and total acidity (34 and 50%) of acid secretion compared to control values. Administered orally at the same doses AE protected against gastric mucosal lesions induced in mice by restraint at 4 C. Exposure of isolated rabbit gastric glands to fractions F8 (10-100 mu M) and F9 (10-300 mu g/ml) decreased the basal [(14)C]-AP uptake by 50 and 60% of control (Ratio = 6.2 +/- 1.1), whereas the remaining fractions were inactive. in the presence of the secretagogues F2 and F4 (30-300 mu g/ml) decreased the [(14)C]-AP uptake induced by histamine (His) with a 100-fold lower potency than that of ranitidine. F5 and F6 reduced the [(14)C]-AP uptake stimulated by carbachol (CCh), but they were 10 to 20-fold less potent than atropine. F8 (diterpene 2) and F9 (flavonoids) decreased both the His- and CCh-induced [(14)C]-AP uptake, whereas F10 (diterpene 1) was inactive against the [(14)C]-AP uptake stimulated by secretagogues. Diterpene 2 was the most active of all tested compounds being 7-fold less potent than ranitidine and equipotent to atropine in reducing acid secretion in vitro. This compound also reduced the gastric H(+), K(+)-ATPase activity by 20% of control, while the remaining fractions were inactive on the proton pump in vitro.Conclusions: the results indicate that Baccharis trimera presents constituents that inhibit gastric acid secretion by acting mainly on the cholinergic regulatory pathway. the plant extract also contains compounds that exert moderate inhibition of the histaminergic regulatory pathway of acid secretion and the gastric proton pump. Altogether these active constituents appear to provide effective inhibition of acid secretion in vivo, which may explain the reputed antiulcer activity of the plant extract. (C) 2011 Elsevier Ireland Ltd. All rights reserved.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundo de Auxilio aos Docentes e Alunos (FADA-UNIFESP)Fundacao de Apoio Institucional Rio Solimoes (UNI-SOL)Universidade Federal de São Paulo, Escola Paulista Med, Dept Pharmacol, Nat Prod Sect, São Paulo, BrazilAmazon Biotechnol Ctr, Lab Pharmacol & Toxicol, Manaus, Amazonas, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Pharmacol, Nat Prod Sect, São Paulo, BrazilWeb of Scienc