ANTICONVULSIVE EFFECT OF URETHANE ON AMINOPYRIDINE-INDUCED EPILEPTIFORM ACTIVITY

THE effects of urethane anaesthesia on the development and spread of i ctal-like epileptiform activity induced by 3-aminopyridine, was invest igated on the somatosensory cortex of rats. Under urethane anaesthesia in most animals only one abortive ictal period appeared with dose-dep endent latency. Urethane completely abolished high frequency afterdisc harges (5-10 Hz) and prevented the development of recurrent seizures i n both primary and mirror foci. Urethane also eliminated ongoing epile ptiform activity induced previously by 3-aminopyridine under nembutal anaesthesia. The antiepileptic effects of urethane on ictal-like activ ity may be the consequence of a presynaptic action through reduction o f glutamate-mediated excitation together with a depressant effect on r esponsiveness of cortical neurones. The afterdischarges of high freque ncy could be essential to development and stabilization of repetitive tonic events in the neocortex.