Relatively few investigators have examined the effect of pregnancy on seizure susceptibility. The present study was designed to determine whether there are any changes in hippocampal seizure thresholds during different stages of pregnancy. Second, we examined the effect of maternal seizures on perinatal mortality. Sixteen female rats were surgically anesthetized and a bipolar electrode stereotaxically implanted into the dorsal hippocampus. Following 1-week recovery, baseline values for seizure threshold were obtained for all rats. Seizure thresholds were then re-determined on days 7, 14, and 21 from baseline. Rats were then mated, and seizure thresholds again re-determined at days 7, 14, and 21 of pregnancy. Vaginal smears were taken 3 times weekly to determine stage of estrus on days stimulated during nonpregnancy. The amount of electrical current required to initiate a hippocampal seizure significantly decreased across each of the three stimulations before pregnancy (P < 01). Vaginal smears indicated that the estrus cycle did not correlate with this change in seizure threshold. There was no effect of pregnancy on seizure susceptibility. However, the mortality of the pups in dams undergoing repetitive electrical stimulation was 34-5% The mortality tended to correlate with longer seizure duration on pregnancy days 7 and 14. Pregnancy had no effect on hippocampal seizure thresholds in this model. Repetitive seizure activity during pregnancy, however, even without behavioral manifestations, led to a high perinatal wastage in pups. Gross and histological examination of the pup brains revealed both micro- and macrohemorrhages. Repetitive electrical stimulation of the maternal rat brain appears to result in fetal intracranial hemorrhage. The mechanism by which these hemorrhages occur requires further investigation.
- Estrus cycle
ASJC Scopus subject areas
- Pediatrics, Perinatology, and Child Health
- Obstetrics and Gynecology