POTENTIATION OF METAPHIT-INDUCED AUDIOGENIC-SEIZURES BY REM-SLEEP DEPRIVATION IN RATS

The possibility that REM sleep deprivation (REMD) induces increased su sceptibility of rats to the convulsive effects of metaphit was investi gated. Metaphit-induced audiogenic seizures were studied in three grou ps of animals: 1) caged controls; 2) large platform animals; and 3) sm all platform, REMD animals. After 48 h of confinement to their environ ments the rats from all three groups were injected with metaphit (10 m g kg-1, IP) and the procedures continued for the next 24 h. Immediatel y after removal from platforms and at 3-h intervals thereafter all rat s were individually subjected to intense sound stimulation. Convulsive responses were recorded and analyzed with respect to incidence, inten sity, and duration. The REMD rats were found to be more sensitive to t he convulsive effects of metaphit compared to nondeprived rats. This w as manifested in significantly shorter latencies to seizures, and sign ificantly higher incidence, severity, and duration of seizures, especi ally of the most severe seizure component-tonic extensor convulsion. I nducing rats to convulse while they were being REM sleep deprived elim inated the REM sleep rebound observed in REMD rats that did not convul se. The occurrence of spontaneous EEG seizures during the undisturbed recovery period reduced REM sleep rebound. The results demonstrate a r eciprocal relation between seizure behavior and REM sleep.