Penicillin spikes in rats. Limitations of a simple model for the study of anticonvulsants.

Direct GABA agonists that suppress spikes induced by penicillin in cats failed to do so in rats. Phenytoin and large doses of THIP increased the rate of spiking activity of the penicillin focus. Only progabide caused marked, initial, short-lasting suppression and a modest reduction of frequency of spikes for 1 hr. Homotaurine (3APS) reduced the amplitude and changed the morphology of the contralateral "mirror" spike. Antagonism of penicillin-induced spikes in rats is considered to be an unsuitable parameter for the screening of anticonvulsant agents.