Status epilepticus induced by pilocarpine and picrotoxin

Status epilepticus induced by pilocarpine and picrotoxin

Author Hamani, C. Google Scholar
Mello, LEAM Google Scholar
Institution Universidade Federal de São Paulo (UNIFESP)
Abstract Since its original description over 10 years ago, the pilocarpine model of status epilepticus (SE) has gained considerable attention. Much work has been done with the model in order to characterize the involvement of different brain structures in seizure genesis and spread. Electrophysiological studies of temporal lobe epileptic slices of both human and animal models, have failed to reveal hyperexcitability, unless blockade of GABAergic inhibition is performed. Thus, we have decided to evaluate potential contributions of picrotoxin, a GABA, channel blocker, on pilocarpine-induced SE. Animals injected with three specific dose combinations (pilocarpine dose/picrotoxin dose), 150/0.5, 75/1.5 and 50/2.0 mg/kg, evoked status epilepticus (SE) within 23, 31 and 27 min, respectively. Ictal events and EEG spikes were initially observed either in the amygdala or in the hippocampus, with a later spread to cerebral cortex. Neuropathological analysis, performed 5-7 days after SE, has shown a high degree of cell loss predominantly in the piriform cortex, amygdala, hippocampus, thalamus and substantia nigra. Mortality rates for 150/0.5, 75/1.5 and 50/2.0 mg/kg (pilocarpine dose/picrotoxin dose) were 53, 42 and 51%, respectively. Single injections of 150 mg/kg of pilocarpine or 3 mg/kg of picrotoxin did not evoke any form of sustained epileptic activity. Previous studies in which simultaneous injections of other GABA(A) antagonists (i.e. bicuculline) and pirocarpine were performed, did not show clear evidences of a synergistic action between these two systems. the present study reveals a proconvulsant role for picrotoxin when co-administered with subconvulsant doses of pilocarpine. Possible mechanisms that might account for the interactions between the cholinergic and GABAergic systems in regard to epileptogenesis are discussed. (C) 1997 Elsevier Science B.V.
Keywords acetylcholine
GABA
epileptogenesis
cholinergic
models of epilepsy
Language English
Date 1997-07-01
Published in Epilepsy Research. Amsterdam: Elsevier B.V., v. 28, n. 1, p. 73-82, 1997.
ISSN 0920-1211 (Sherpa/Romeo, impact factor)
Publisher Elsevier B.V.
Extent 73-82
Origin http://dx.doi.org/10.1016/S0920-1211(97)00030-2
Access rights Closed access
Type Article
Web of Science ID WOS:A1997XL61200008
URI http://repositorio.unifesp.br/handle/11600/25758

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