Electrophysiologic abnormalities of the hippocampus in the pilocarpine/cycloheximide model of chronic spontaneous seizures

Electrophysiologic abnormalities of the hippocampus in the pilocarpine/cycloheximide model of chronic spontaneous seizures

Autor Longo, Beatriz Monteiro Autor UNIFESP Google Scholar
Sanabria, Emilio Rafael Garrido Autor UNIFESP Google Scholar
Gabriel, S. Google Scholar
Mello, Luiz Eugenio Araujo de Moraes Autor UNIFESP Google Scholar
Instituição Universidade Federal de São Paulo (UNIFESP)
Humboldt Univ
Resumo Purpose: Mossy fiber sprouting (MFS) and synaptic reorganization in the dentate gyrus (1)(3) is considered one of the physiopathologic mechanisms in temporal lobe epilepsy. Supragranular MFS can be blocked by cycloheximide (CHX) without interfering with the genesis of spontaneous recurrent seizures. the aim of this study was to investigate electrophysiologic properties of the hippocampus in the CHX/pilocarpine (CHX/PILO) model as compared with the conventional PILO model.Methods: in vitro electrophysiology was performed 2 months after status epilepticus (SE) induction using extracellular recordings in hippocampal slices from PILO (n = 8) and CHX/PILO animals (n = 10). Field potential responses were evoked in the CA1 and DG regions during perfusion with normal artificial cerebrospinal fluid (aCSF) and aCSF containing 3.5, 5, or 8 mM K+ without or with bicuculline added. Neo-Timm staining was used for the assessment of supragranular MFS.Results: Evoked potentials in PILO- and CHX/PILO-treated rats displayed small-amplitude polyspiking activity (epileptiform responses) in CAI and an apparently normal isolated population spike in DG. More important, PILO and CHX/PILO animals did not differ regarding electrophysiologic abnormalities, even under high K+ or high K+/bicuculline. Analysis of the neo-Timm staining revealed strong supragranular MFS in PILO-injected rats and significantly less staining in CHX/PILO rats. Thus, occurrence of abnormal stimulus responses and high K+- or high K+/bicuculline-induced epileptiform activities did not depend on the degree of MFS.Conclusions: We therefore suggest that other mechanisms such as anomalous intrinsic bursting and disinhibition rather than MFS might account for the increased hippocampal hyperexcitability in this model.
Palavra-chave epilepsy
mossy fiber sprouting
dentate gyrus
Idioma Inglês
Data de publicação 2002-01-01
Publicado em Epilepsia. Malden: Blackwell Publishing Inc, v. 43, p. 203-208, 2002.
ISSN 0013-9580 (Sherpa/Romeo, fator de impacto)
Publicador Blackwell Publishing Inc
Extensão 203-208
Fonte http://dx.doi.org/10.1046/j.1528-1157.43.s.5.4.x
Direito de acesso Acesso aberto Open Access
Tipo Artigo
Web of Science WOS:000177445900038
Endereço permanente http://repositorio.unifesp.br/handle/11600/26684

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