Seizure susceptibility in intact and ovariectomized female rats treated with the convulsant pilocarpine.
Despite numerous neuroendocrinological studies of seizures, the influence of estrogen and progesterone on seizures and epilepsy remains unclear. This may be due to the fact that previous studies have not systematically compared distinct endocrine conditions and included all relevant controls. The goal of the present study was to conduct such a study using pilocarpine as chemoconvulsant. Thus, age and weight-matched, intact or ovariectomized rats were tested to determine incidence of status epilepticus and to study events leading to status. Intact female rats were sampled at each cycle stage (proestrus, estrus, metestrus, or diestrus 2). Convulsant was administered at the same time of day, 10:00-10:30 a.m. Statistical analysis showed that there was a significantly lower incidence of status on the morning of estrus, but differences were attenuated in older animals. Ovariectomized rats were distinct in their rapid progression to status. These results show that the incidence of status in female rats following pilocarpine injection, and the progression to pilocarpine-induced status, are influenced by reproductive state as well as age. The hormonal milieu present specifically on the morning of estrus appears to decrease susceptibility to pilocarpine-induced status, particularly at young ages. In contrast, the chronic absence of reproductive steroids that characterizes the ovariectomized rat leads to a more rapid progression to status. This dissociation between incidence vs. progression provides new insight into the influence of estrogen and progesterone on seizures.
Scharfman
Helen E
HE
Center for Neural Recovery and Rehabilitation Research (CNRRR), Helen Hayes Hospital, New York State Department of Health, Rte 9W, West Haverstraw, NY 10993-1195, USA. scharfmanh@helenhayeshosp.org
Goodman
Jeffrey H
JH
Rigoulot
Marie-Aude
MA
Berger
Russell E
RE
Walling
Susan G
SG
Mercurio
Thomas C
TC
Stormes
Kerry
K
Maclusky
Neil J
NJ
D000818:Animals; D003292:Convulsants / Q000633:toxicity*; D004195:Disease Models, Animal; D004198:Disease Susceptibility; D004967:Estrogens / Q000097:blood; D030762:Estrous Cycle / Q000502:physiology*; D005260:Female; D010052:Ovariectomy; D010862:Pilocarpine / Q000633:toxicity*; D011374:Progesterone / Q000097:blood; D011863:Radioimmunoassay; D051381:Rats; D017207:Rats, Sprague-Dawley; D012640:Seizures / Q000139:chemically induced* / Q000503:physiopathology; D013226:Status Epilepticus / Q000139:chemically induced*; D013739:Testosterone / Q000097:blood
D003292:Convulsants; D004967:Estrogens; D010862:Pilocarpine; D013739:Testosterone; D011374:Progesterone