Navegando por Palavras-chave "STATUS EPILEPTICUS"
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- ItemSomente MetadadadosCIRCUIT MECHANISMS of SEIZURES in the PILOCARPINE MODEL of CHRONIC EPILEPSY - CELL LOSS and MOSSY FIBER SPROUTING(Lippincott-raven Publ, 1993-11-01) Mello, LEAM; Cavalheiro, E. A.; Tan, A. M.; Kupfer, W. R.; Pretorius, J. K.; Babb, T. L.; Finch, D. M.; Universidade Federal de São Paulo (UNIFESP); UNIV CALIF LOS ANGELESWe used the pilocarpine model of chronic spontaneous recurrent seizures to evaluate the time course of supragranular dentate sprouting and to assess the relation between several changes that occur in epileptic tissue with different behavioral manifestations of this experimental model of temporal lobe epilepsy. Pilocarpine-induced status epilepticus (SE) invariably led to cell loss in the hilus of the dentate gyrus (DG) and to spontaneous recurrent seizures. Cell loss was often also noted in the DG and in hippocampal subfields CA1 and CA3. the seizures began to appear at a mean of 15 days after SE induction (silent period), recurred at variable frequencies for each animal, and lasted for as long as the animals were allowed to survive (325 days). the granule cell layer of the DG was dispersed in epileptic animals, and neo-Timm stains showed supra- and intragranular messy fiber sprouting. Supragranular messy fiber sprouting and dentate granule cell dispersion began to appear early after SE (as early as 4 and 9 days, respectively) and reached a plateau by 100 days. Animals with a greater degree of cell loss in hippocampal field CA3 showed later onset of chronic epilepsy (r = 0.83, p < 0.0005), suggesting that CA3 represents one of the routes for seizure spread. These results demonstrate that the pilocarpine model of chronic seizures replicates several of the features of human temporal lobe epilepsy (hippocampal cell loss, supra- and intragranular messy fiber sprouting, dentate granule cell dispersion, spontaneous recurrent seizures) and that it may be a useful model for studying this human condition. the results also suggest that even though a certain amount of cell loss in specific areas may be essential for chronic seizures to occur, excessive cell loss may hinder epileptogenesis.
- ItemSomente MetadadadosDECREASED SUSCEPTIBILITY TO SEIZURES INDUCED BY BICUCULLINE AFTER TRANSIENT BILATERAL CLAMPING of the CAROTID ARTERIES in RATS(Springer, 1991-01-01) Sieklucka, M.; Bortolotto, Z.; Heim, C.; Block, F.; Sontag, K. H.; UNIV GOTTINGEN; MAX PLANCK INST EXPTL MED; INST CLIN PATHOL; Universidade Federal de São Paulo (UNIFESP)Rats were exposed for 24 min to bilateral clamping of the common carotid arteries (BCCA) in pentobarbital anaesthesia. 14 days later the animals were subjected to subcutaneous injection of (+)-bicuculline (3 or 4 mg/kg). A significantly decreased susceptibility to bicuculline-induced seizures could be observed in BCCA treated rats compared with sham operated controls. It is suggested that BCCA treatment protects animals against status epilepticus and lethal toxicity produced by bicuculline. Electrographic recordings of the BCCA animals revealed no ictal activity within 1 h after bicuculline injection. An analysis of the GABA content showed a significant increase in the hippocampus (HPC), frontal cortex (FCX), parietal cortex and substantia nigra in BCCA animals compared with controls. It is therefore possible that an increase in GABA content postsynaptically counteracts the GABA(A) antagonistic effect of bicuculline in BCCA animals thus preventing the normal seizure inducing effect of this substance.
- ItemSomente MetadadadosTHE PILOCARPINE MODEL of EPILEPSY(Masson Divisione Periodici, 1995-02-01) Cavalheiro, E. A.; Universidade Federal de São Paulo (UNIFESP)The systemic administration of a potent muscarinic agonist pilocarpine in rats promotes sequential behavioural and electrographic changes that can be divided in three distinct periods: (a) an acute period that built up progressively into a limbic status epilepticus and that lasts 24 h, (b) a silent period with a progressive normalization of EEG and behaviour which varies fi-om 4 to 44 days,,and (c) a chronic period with spontaneous recurrent seizures (SRSs). the main features of the SRSs observed during the long-term period resemble those of human complex partial seizures and recurs 2-3 times per week per animal, Therefore, this novel and unique experimental approach may serve as a model of epilepsy mimicking the human condition.
- ItemSomente MetadadadosSUPPRESSION OF PILOCARPINE-INDUCED STATUS EPILEPTICUS AND THE LATE DEVELOPMENT OF EPILEPSY IN RATS(Springer, 1995-01-01) Lemos, Tadeu [UNIFESP]; Cavalheiro, Esper Abrão [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)Status epilepticus (SE) has been related to subsequent development of epilepsy. The present work was aimed at elucidating the relationship between the duration of pilocarpine- (PILO)-induced SE and the subsequent development of epilepsy in rats. The latency for the appearance of the first spontaneous seizure, the frequency of spontaneous seizures, the cell density in the hippocampal formation and the density of supragranular neo-Timm staining were monitored. At 30 min, 1, 2 and 6 h after the beginning of SE, animals were treated with diazepam plus pentobarbital. In non-treated rats, SE remitted spontaneously. Animals exhibiting 30 min of PILO-induced SE did not develop spontaneous seizures. Hippocampal cell counts and the density of neo-Timm staining in these animals were similar to those observed in control rats. In the other groups longer SE durations were related to: shorter latency for the appearance of the first spontaneous seizure, increased number of the spontaneous recurrent seizures, severe cell loss in the hippocampal formation, or increased supragranular neo-Timm staining. These data suggest that more than 30 min of SE is required to produce hippocampal damage with subsequent synaptic reorganization of the messy fibre pathway that could account for SRSs observed in the PILO model of epilepsy.