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

Intestine of dystrophic mice presents enhanced contractile resistance to stretching despite morphological impairment

Protein dystrophin is a component of the dystrophin-associated protein complex, which links the contractile machinery to the plasma membrane and to the extra-cellular matrix. Its absence leads to a condition known as Duchenne muscular dystrophy (DMD), a disease characterized by progressive skeletal muscle degeneration, motor disability, and early death. in mdx mice, the most common DMD animal model, loss of muscle cells is observed, but the overall disease alterations are less intense than in DMD patients. Alterations in gastrointestinal tissues from DMD patients and mdx mice are not yet completely understood. Thus, we investigated the possible relationships between morphological (light and electron microscopy) and contractile function (by recording the isometric contractile response) with alterations in Ca2+ handling in the ileum of mdx mice. We evidenced a 27% reduction in the ileal muscular layer thickness, a partial damage to the mucosal layer, and a partial damage to mitochondria of the intestinal myocytes. Functionally, the ileum from mdx presented an enhanced responsiveness during stretch, a mild impairment in both the electromechanical and pharmacomechanical signaling associated with altered calcium influxinduced contraction, with no alterations in the sarcoplasmic reticulum Ca2+ storage (maintenance of the caffeine and thapsigargin-induced contraction) compared with control animals. Thus, it is evidenced that the protein dystrophin plays an important role in the preservation of both the microstructure and ultrastructure of mice intestine, while exerting a minor but important role concerning the intestinal contractile responsiveness and calcium handling.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Universidade Federal de São Paulo, Escola Paulista Med, Dept Biophys, BR-04023062 São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Ctr Microscopia Eletron, BR-04023062 São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Pharmacol, BR-04023062 São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Biophys, BR-04023062 São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Ctr Microscopia Eletron, BR-04023062 São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Pharmacol, BR-04023062 São Paulo, BrazilFAPESP: 07/58132-9FAPESP: 12/15716-9FAPESP: 07/59976-6Web of Scienc

Effects of hecogenin and its possible mechanism of action on experimental models of gastric ulcer in mice

This study investigates the gastroprotective effects of hecogenin, a steroid saponin isolated from Agave sisalana, on experimental models of gastric ulcer. Male Swiss mice were used in the models of ethanol-and indometacin-induced gastric ulcer. To clarify the hecogenin mechanism of action, the roles of nitric oxide (NO), sulfhydryls (GSH), K-ATP(+) channels and prostaglandins were also investigated, and measurements of lipid peroxidation (TBARS assay) and nitrite levels in the stomach of hecogenin-treated and untreated animals were performed. Furthermore, the effects of hecogenin on myeloperoxidase (MPO) release from human neutrophils were assessed in vitro. Our results showed that hecogenin (3.1, 7.5, 15, 30, 60 and 90 mg/kg, p.o.) acutely administered, before ethanol or indomethacin, exhibited a potent gastroprotective effect. Although the pretreatments with L-NAME, an iNOS inhibitor, and capsazepine, a TRPV1 receptor agonist, were not able to reverse the hecogenin effect, this was reversed by glibenclamide, a K-ATP(+) blocker, and indomethacin in the model of ethanol-induced gastric lesions. the hecogenin pretreatment normalized GSH levels and significantly reduced lipid peroxidation and nitrite levels in the stomach, as evaluated by the ethanol-induced gastric lesion model. the drug alone increased COX-2 expression and this effect was further enhanced in the presence of ethanol. It also decreased MPO release and significantly protected the gastric mucosa. in conclusion, we showed that hecogenin presents a significant gastroprotective effect that seems to be mediated by K-ATP(+) channels opening and the COX-2/PG pathway. in addition, its antioxidant and anti-inflammatory properties may play a role in the gastroprotective drug effect. (C) 2012 Elsevier B. V. All rights reserved.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Univ Fed Ceara, Dept Physiol & Pharmacol, BR-60431270 Fortaleza, Ceara, BrazilUniv Fed Ceara, Dept Pharm, BR-60431270 Fortaleza, Ceara, BrazilUniv Fed Paraiba, Dept Pharmaceut Sci, BR-58100000 Joao Pessoa, Paraiba, BrazilUniv Fed Ceara, Dept Morphol, BR-60431270 Fortaleza, Ceara, BrazilUniversidade Federal de São Paulo, Dept Pharmacol, BR-04044020 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Pharmacol, BR-04044020 São Paulo, BrazilWeb of Scienc

The water extract of Coleus barbatus Benth decreases gastric secretion in rats

Coleus barbatus (Labiatae) Benth is popularly used in Brazil "for the healing of liver and stomach diseases". The water extract (WE 1 to 10 g/Kg, p.o.) of stem and leaves given to rats and mice did not induce signs of intoxication. Preveious treatment of mice with WE (1 g/kg, p.o.) shortened the sleeping time induced by pentobarbital (50 mg/Kg, i.p.) by 37 por cento, althoyugh the extract alone did not increase the spontaneous activity nor did it induce hyperexcitability. In mice WE (2 g/Kg, p.o.) increased the intestinal transit of charcoal by 30 por cento, while reduced gastric secretions ion rats treated with WE (2g/Kg intraduodenal) 3,9 ± 1.0 to 0.5 ± 0.2 ml/4h, respectively). The treatment also reduced the total acid secretion from 34.4 ± 11.0 to 2.7 ± 0.5 mEq/l and raisedgastric pH from 2.2 ± 0.3 to 6.5 ± 0.8. Treatment with WE (2g/Kg, p.o.) protected against gastric ulcers induced by stress (5.3 ± 1.6 and 1.5 ± 0.5 ulcers/cm²), but did nor protect against indonethacin induced ulcers. The results show that the water extract of C barbatus Benth produces mild stimulation of thecentral nervous system and increases intestinal movements. The extract also reduces gastric secretion indicating an antidyspeptic activity, and protects against gastric ulcers induced by stress

Inhibition of gastric secretion by a water extract from Baccharis triptera, Mart

Baccharus triptera Mart, is a widespread Compositae usedin Brazilian folk medicine to treat gastrointestinal disturbances, rheumatic disease, mild fever, diabetes and as an anti-helminthic. Water extract of small branches of the plant (WE) administered to mice and rats (0.1 to 2 g/Kg, p.o) did not alter spontaneous motor activity, sleeping time induced by barbiturates or the tailflick response in mice. The extract decreasedby 40 por cento the number of writhings induced by 0.8 por cento scetic acid, i.p., but did not influence paw edema induced by carrageenan or dextran in rats WE (2g/Kg, p.o.) decreased the intestinal transit of charcoal in mice by 20//. Gastric secretion in pylorus ligated rats was reduced after treatment with WE (1 and 2 g/Kg. i.p. or intraduodenal and the gastric pH was raised. The extract (1 g/Kg, p.o.) prevented gastric ulcers induced in rats by immobilization at 4ºC, but not those induced by indomethacin (10 mg/Kg, s.c.). The results indicate that WE may relieve gastrointestinal disorders by reducing acid secretion and gastrointestinal hiperactivity. Neither analgesic nor anti-inflammatory activities were detectable.Escola Paulista de Medicina Departamento de Farmacologia Setor de Produtos NaturaisEMBRAPA CENARGEMUNIFESP, EPM, Depto. de Farmacologia Setor de Produtos NaturaisSciEL

Pharmacological and toxicological evaluation of Rhizophora mangle L., as a potential antiulcerogenic drug: Chemical composition of active extract

Rhizophora mangle L. is a vegetal species widely distributed in Cuba and other Caribbean countries. This species is characterized by several ethnobotanical activities as antiseptic, astringent, as well for treating skin ulcers. In the present work, we describe a pharmacological, toxicological and chemical evaluation of this plant by its use in human medicine for the treatment of gastroduodenal ulcers. The acute gastric ulcer's models were: acute gastric ulcers induced by ethanol; indomethacin; pyloric ligation; stress and immobility in cool in mice. The antisecretor effect of the extract was evaluated by pyloric ligation model. Other pharmacological tests were planned with the freeze -dried extract of R. mangle, as part of the evaluation on other systems to known secondary or adverse effects. These tests included the activity of the antiulcer active extract on intestinal transit, activity over arterial pressure, ileum activity and absorption of glucose in gut. The chemical profile of this extract by fatty acids was studied by Gas Chromatography/Mass Spectrometry. Some toxicological studies (genotoxicity) were carried out. The aqueous extract of R. mangle bark showed gastroprotective, antisecretor effects, and it induced a recovery of PGE 2 levels in doses-dependence manner comparable of knowledge antiulcerogenic medicaments. No effect was observed by arterial pressure in rats and the intestinal transit was inhibited by R. mangle. The intestinal motility was stimulated. Antiulcer active extract inhibit the glucose absoprtion in gut. This extract presented 4% of saturated and not saturated long chain's fatty acids (C10:0 at C24:0). No toxicological signs were obtained by this extract

Sympathomimetic effects of Scoparia dulcis L and catecholamines isolated from plant extracts

The herb Scoparia dulcis L. is used in Brazilian folk medicine to treat bronchitis, gastric disorders, haemorrhoids, insect bites and skin wounds, and in oriental medicine to treat hypertension. A previous study has shown that extracts of S. dulcis have analgesic and anti-inflammatory properties in this work the sympathomimetic activity of an ethanolic extract of Scoparia dulcis L. has been investigated in rodent preparations in-vivo and in-vitro.Administration of the extract (0.5-2 mg kg(-1), i.v.) to anaesthetized rats produced dose-related hypertension blocked by the alpha-adrenoceptor antagonist prazosin (1 mg kg(-1)). Partition of the extract in chloroform-water yielded an aqueous phase 20 times more potent than the extract; this produced hypertension in either reserpine-treated or pithed rats. in untreated and reserpine-treated rats the same fraction (1-3 x 10(3) mu g mL(-1)) produced concentration-dependent contractions of the vas deferens musculature parallel to those obtained with noradrenaline (10(-8)-10(-4) M). Prazosin (10(-7) M) reduced the maximum contractile effect of the aqueous fraction, and shifted the concentration-response curves for noradrenaline to the right. The aqueous fraction (25 and 50 mu g mL(-1)) increased the inotropism of electrically driven left atria of rats, the effect being blocked by propranolol (0.4 mu g mL(-1)). in preparations of guinea-pig tracheal rings the aqueous fraction (1-3 x 10(3) mu g mL(-1)) relaxed the muscle contraction induced by histamine (10(-4) M) in proportion to the concentration. The effect was antagonized competitively by propranolol (1.5 mu M), High-performance liquid-chromatographic analysis of the aqueous fraction revealed the presence of both noradrenaline and adrenaline in the plant extract.The results indicated that both catecholamines may account for the hypertensive and inotropic effects obtained after parenteral administration of S. dulcis extracts. This sympathomimetic activity is, however, unrelated to the previously reported analgesic and anti-inflammatory properties of the plant extract, but may explain its effectiveness upon topical application in the healing of mucosal and skin wounds.UNIV FED SAO PAULO,ESCUELA PAULISTA MED,DEPT PHARMACOL,NAT PROD SECT,BR-04044020 SAO PAULO,BRAZILUNIV FED SAO PAULO,ESCUELA PAULISTA MED,DEPT PHARMACOL,NAT PROD SECT,BR-04044020 SAO PAULO,BRAZILWeb of Scienc