Region-specific modulation of limbic seizure susceptibility by ovarian steroids

Libor Velíšek, Jana Velíšková, Anne M. Etgen, Patric K. Stanton, Solomon L. Moshé

Research output: Contribution to journalArticle

32 Scopus citations

Abstract

Gonadal steroid hormones can markedly affect seizure susceptibility. Ovariohysterectomized female rats given ovarian steroid hormone supplements were used to evaluate the effects of ovarian steroids on epileptiform activity in hippocampal slices in vitro and on flurothyl-induced seizures in vivo. Seizure susceptibility was compared in the entorhinal cortex (EC) and CA1 regions of the hippocampus perfused with Mg2+-free medium, which leads to epileptiform discharges caused by a relief of voltage-dependent NMDA receptor block. After in vivo treatment with 500 μg of progesterone for 2 h prior to slice preparation, the latency to onset of low Mg2+-induced epileptiform activity of slices was significantly prolonged compared to slices from controls. In contrast, progesterone replacement accelerated the development of epileptiform activity in the CA1 region. Neither estrogen alone (2 x 2 μg of estradiol benzoate, 48 and 24 h prior to the experiment), nor a combined treatment with estrogen plus progesterone, significantly affected seizure susceptibility in either CA1 or the EC. There were no consistent effects of estrogen or progesterone, alone or in combination, on flurothyl-induced seizures in vivo. The data suggest that in vitro, progesterone alters seizure susceptibility in a site- and seizure model- specific fashion. The differential effects of progesterone may be due to differential expression of progesterone receptor isoforms or metabolites in specific brain areas suggesting that selective modulation of NMDA receptor- dependent epileptiform activity may play a role in hormonal effects on epileptogenesis.

Original languageEnglish (US)
Pages (from-to)132-138
Number of pages7
JournalBrain research
Volume842
Issue number1
DOIs
StatePublished - Sep 18 1999

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Keywords

  • Entorhinal cortex
  • Estrogen
  • Flurothyl
  • Hippocampus
  • Progesterone
  • Seizure

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology

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