Abstracts

RATIONALE: In women, seizure frequency varies in relation to hormonal variations during the menstrual cycle. Thus, we studied in female rats the influence of estrous cycle on characteristics of status epilepticus (SE) induced by lithium-pilocarpine and later occurrence of spontaneous recurrent seizures (SRS). METHODS: SE was induced by lithium (3 meq/kg) followed 20 h later by pilocarpine (24 mg/kg) in 31 adult female rats. At 30 min before pilocarpine, vaginal smears were taken. Two weeks after SE, rats were implanted with cortical electrodes and underwent regular observation and EEG recordings for occurrence of SRS. RESULTS: - Within 5 rats in metestrus (low levels of estrogens and high levels of progesterone), 5 presented SE: 1 died during SE; 4 developed SRS. - Within 12 rats in estrus (low levels of both hormones), 10 presented SE: 2 died during SE; none of the 8 surviving rats developed SRS. - Within 14 rats in proestrus (peak levels of both hormones), 7 presented SE: 4 died during SE; 2/3 surviving rats developed SRS. CONCLUSIONS: Thus, hormonal variations occurring during the estrous cycle modulate the induction of SE and occurrence of SRS. The hormone-related neuronal damage underlying the long-term consequences of SE is under investigation.