The effects of beta-carboline carboxylic acid ethyl ester and its free acid, administered ICV, on the anticonvulsant activity of diazepam and sodium valproate in the mouse.

The effects of intracerebroventricular (ICV) beta-carboline carboxylic acid ethyl ester (beta-CCE) and its free acid on the protective effects of diazepam against leptazol- and R05-3663-induced convulsions were investigated in mice and compared with their effects on the antileptazol effect of sodium valproate, in an attempt to demonstrate a specific central effect of beta-CCE on benzodiazepine function. The results show that a small dose (1 microgram) of beta-CCE but not its free acid (in doses of up to 100 micrograms) was able to reverse the protective effects of diazepam against leptazol- and R05-3663-induced convulsions, whereas the effects of sodium valproate, a nonbenzodiazepine anticonvulsant, could not be reversed by these beta-carboline derivatives.