3 resultados para Brain homeostasis

em Repositório Institucional UNESP - Universidade Estadual Paulista "Julio de Mesquita Filho"


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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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This work evaluated the potential of the isoforms of methamidophos to cause organophosphorus-induced delayed neuropathy (OPIDN) in hens. In addition to inhibition of neuropathy target esterase (NTE) and acetylcholinesterase (AChE), calpain activation, spinal cord lesions and clinical signs were assessed. The isoforms (+)-, (+/-)- and (-)-methamidophos were administered at 50 mg/kg orally; tri-ortho-cresyl phosphate (TOCP) was administered (500 mg/kg, po) as positive control for delayed neuropathy. The TOCP hens showed greater than 80% and approximately 20% inhibition of NTE and AChE in hen brain, respectively. Among the isoforms of methamidophos, only the (+)-methamidophos was capable of inhibiting NTE activity (approximately 60%) with statistically significant difference compared to the control group. Calpain activity in brain increased by 40% in TOCP hens compared to the control group when measured 24h after dosing and remained high (18% over control) 21 days after dosing. Hens that received (+)-methamidophos had calpain activity 12% greater than controls. The histopathological findings and clinical signs corroborated the biochemical results that indicated the potential of the (+)-methamidophos to be the isoform responsible for OPIDN induction. Protection against OPIDN was examined using a treatment of 2 doses of nimodipine (1 mg/kg, i.m.) and one dose of calcium gluconate (5 mg/kg, iv.). The treatment decreased the effect of OPIDN-inducing TOCP and (+)-methamidophos on calpain activity, spinal cord lesions and clinical signs. (C) 2012 Elsevier B.V. All rights reserved.

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The median preoptic nucleus (MnPO) is one of most important site of the lamina terminalis implicated in the regulation of hydro electrolytic and cardiovascular balance. The purpose of this study was to determine the effect of L-Type calcium channel antagonist, nifedipine, on the increase of median arterial blood pressure (MAP) induce by angiotensin II (ANG II) injected into the MnPO. The influence of nitric oxide (NO) on nifedipine antipressor action has also been studied by utilizing N W-nitro-L-arginine methyl ester (L-NAME) (40 μg 0.2 μL -1) a NO synthase inhibitor (NOSI), 7-nitroindazole (7-NIT) (40 μg 0.2 μL -1), a specific neuronal NO synthase inhibitor (nNOSI) and sodium nitroprusside (SNP) (20 μg 0.2 μL -1) a NO donor agent. We have also investigated the central role of losartan and PD123349 (20 nmol 0.2 μL -1), AT 1 and AT 2, respectively (selective non peptide ANG II receptor antagonists), in the pressor effect of ANG II (25 pmol 0.2 μL -1) injected into the MnPO. Male Wistar rats weighting 200-250 g, with cannulae implanted into the MnPO were utilized. Losartan injected into the MnPO, prior to ANG II, blocked the pressor effect of ANGII. PD 123319 only decreased the pressor effect of ANG II. Rats pre-treated with either 50 μg 0.2 μL -1 or 100 μg 0.2 μL -1 of nifedipine, followed by 25 pmol 0.2 μL -1 of ANG II, decreased ANG II-pressor effect. L-NAME potentiated the pressor effect of ANG II. 7-NIT injected prior to ANG II into the MnPO also potentiated the pressor effect of ANGII but with less intensity than that of L-NAME. SNP injected prior to ANG II blocked the pressor effect of ANG II. The potentiation action of L-NAME and 7-NIT on ANG II-pressor effect was blocked by prior injection of nifedipine. The results described in this study provide evidence that calcium channels play important roles in central ANG II-induced pressor effect. The structures containing NO in the brain, such as MnPO, include both endothelial and neuronal cells, which might be responsible for the influence of nifedipine on the pressor effect of ANG II. These data have shown the functional relationship between L-Type calcium channel and a free radical gas NO in the MnPO, on the control of ANG II-induced pressor effect acting in AT 1 and AT 2 receptors.