Navegando por Palavras-chave "Convulsion"
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- ItemAcesso aberto (Open Access)Proconvulsant effects of high doses of venlafaxine in pentylenetetrazole-convulsive rats(Associação Brasileira de Divulgação Científica, 2002-04-01) Santos-Junior, Jair Guilherme [UNIFESP]; Do Monte, F.h.m.; Russi, M.; Agustine, P.e.; Lanziotti, Vanusa Maria Nascimento Bispo; Universidade Federal de São Paulo (UNIFESP); Universidade do Estado de Santa Catarina Centro de Ciências Agroveterinárias Departamento de MorfofisiologiaVenlafaxine, an atypical antidepressant drug, has been used to treat several neurological disorders, presenting excellent efficacy and tolerability. Clinical seizures after venlafaxine treatment have occasionally been reported when the drug was used at very high doses or in combination with other medications. The aim of the present study was to investigate the convulsant effects of venlafaxine in rats under controlled laboratory conditions. Adult male Wistar rats (8 per group) receiving venlafaxine or saline at the doses of 25-150 mg/kg were subjected 30 min later to injections of pentylenetetrazole at the dose of 60 mg/kg. The animals receiving 75, 100 and 150 mg/kg venlafaxine presented increased severity of convulsion when compared to controls (P = 0.02, P = 0.04, and P = 0.0004, respectively). Indeed, an increased percentage of death was observed in these groups (50, 38, and 88%, respectively) when compared to the percentage of death in the controls (0%). The group receiving 150 mg/kg showed an reduction in death latency (999 ± 146 s) compared to controls (1800 ± 0 s; cut-off time). Indeed, in this group, all animals developed seizures prior to pentylenetetrazole administration. Surprisingly, the groups receiving venlafaxine at the doses of 25 and 50 mg/kg showed a tendency towards an increase in the latency to the first convulsion. These findings suggest that venlafaxine at doses of 25 and 50 mg/kg has some tendency to an anticonvulsant effect in the rat, whereas doses of 75, 100 and 150 mg/kg presented clear proconvulsant effects in rats submitted to the pentylenetetrazole injection. These findings are the first report in the literature concerning the role of venlafaxine in seizure genesis in the rat under controlled conditions.
- ItemSomente MetadadadosRats With Different Thresholds to Clonic Convulsions Induced by DMCM Differ in the Binding of [H-3]-MK-801 and [H-3]-Ouabain in the Membranes of Brain Regions(Springer, 2012-07-01) Contó, Marcos Brandão [UNIFESP]; Barbosa de Carvalho, Jose Gilberto [UNIFESP]; Venditti, Marco Antonio Campana [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)Considering the putative participation of N-methyl-D-aspartate (NMDA) receptors and the Na+, K+-ATPase enzymes in the susceptibility to convulsions induced by the benzodiazepine inverse agonist methyl 6,7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate (DMCM), the present study sought to determine if rats with high (HTR) and low (LTR) thresholds to clonic convulsions induced by DMCM differed in the following aspects: the binding of NMDA receptors by [H-3]-MK-801, Na+, K+-ATPase activity (K+-stimulated p-nitrophenylphosphatase) and high-affinity [H-3]-ouabain binding to membranes from discrete brain regions. Compared to the HTR subgroup, the LTR subgroup presented a lower binding of [H-3]-MK-801 in the hippocampus, frontal cortex and striatum. the subgroups did not differ in K+-p-nitrophenylphosphatase activity, but the LTR subgroup had a lower density of isozymes with a high-affinity to ouabain in the brainstem and in the frontal cortex and a lower affinity to ouabain in the hippocampus than the HTR subgroup. These results suggest that NMDA receptors and ouabain-sensitive Na+, K+-ATPase isozymes may underlie the susceptibility to DMCM-induced convulsions.
- ItemSomente MetadadadosRelationship between thresholds to convulsions induced by a benzodiazepine inverse agonist and [H-3]-L-glutamate binding in the membranes of brain regions(Springer, 2013-04-01) Contó, Marcos Brandão [UNIFESP]; Barbosa de Carvalho, Jose Gilberto [UNIFESP]; Venditti, Marco Antonio Campana [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)Although some studies have investigated the influence of kindling model of epilepsy on the glutamatergic neurotransmission, the relation between glutamatergic receptors and seizure susceptibility remains unclear. the present study sought to determine if rats with high (HTR) and low (LTR) thresholds to clonic convulsions induced by the benzodiazepine inverse agonist DMCM differed in the [H-3]-l-glutamate binding to membranes from discrete brain regions. Compared to the HTR subgroup, the LTR subgroup presented a lower binding of [H-3]-l-glutamate in the hippocampus, frontal cortex and amygdala plus limbic cortex, suggesting that glutamatergic receptors in these brain regions may underlie the susceptibility to DMCM-induced convulsions.