Anticonvulsant modification of tripelennamine effects on the electrographic activity of the cat brain

The modification of tripelennamine effects on the electrographic activity of cat brain by pretreatment with phenobarbital, trimethadione, diphenylhydantoin or saline was examined with the aid of power spectral density analysis. Only phenobarbital and trimethadione pretreatments effectively increased the tripelennamine dose required for induction of paroxysmal activity. Diphenylhydantoin and phenobarbital pretreatments resulted in greater cortical amplitude increases during tripelennamine infusions, reaching mean normalized power values of 520 and 330%, respectively, just prior to paroxysm. With trimethadione pretreatment marked power changes were not induced during the tripelennamine infusion although more sharp wave activity was noted than was seen with saline pretreatment. Tripelennamine-induced hippocampal power changes were minimal except with diphenylhydantoin pretreatment, reaching 190% just prior to paroxysm. Dominant hippocampal 4.0–4.5 Hz activity, which was induced by tripelennamine with saline pretreatment, was reduced or eliminated with all anticonvulsant pretreatments. The findings indicate that the previously suggested role of hippocampal theta activity in the production of tripelennamine-induced paroxysmal activity is abolished by anticonvulsant pretreatment. The cerebral cortex appears to play a primary role in the production of epileptiform activity by tripelennamine in the presence of anticonvulsants.