THE EFFECT OF NIMODIPINE ON PICROTOXIN-INDUCED SEIZURES

The effects of the calcium channel antagonist, nimodipine, on picrotoxin-induced myoclonic (MYO) and generalized tonic-clonic (GTC) seizures were investigated in male and female rats. In males, a dose-response study of nimodipine's effects on seizures induced by different doses of picrotoxin was conducted. In a second experiment, female rats were tested for latency to and incidence of MYO and GTC seizures after being pretreated with nimodipine 2 hr, 24 hr, or 72 hr prior to seizure testing. The results showed that, in males, various doses of nimodipine significantly increased the mean latencies to MYO and GTC seizures and significantly reduced the incidence of GTC seizures. In females, nimodipine significantly reduced the incidence and/or increased the latency of GTC seizures when given 24 hr or 72 hr prior to administration. In addition to the anticonvulsant effects, nimodipine significantly increased survival after seizures in both males and females even when it had no significant effects on seizure incidence or latency. The results of this study support the hypothesis of calcium involvement in seizure induction. However, the sex- and time-dependent nature of the nimodipine effects as well as the effects of nimodipine on survival after seizures suggest that the relationship between calcium and seizure activity is complex. © 1990.