Specific antagonism of GABA-mediated postsynaptic inhibition in cultured mammalian spinal cord neurons: a common mode of convulsant action.

Mammalian spinal neurons grown in tissue culture were used to study the effects of the four convulsants-penicillin, pentylenetetrazol, picrotoxin, and bicuculline-on these neurons' responses to amino acids. Bath application of all four convulsants produced paroxysmal depolarizing events in the neurons; iontophoresis of the four convulsants selectively depressed responses produced by iontophoresis of the putative inhibitory transmitter GABA, and effected this depression without altering either inhibitory responses to beta-alanine or glycine, or excitation mediated by glutamate. These results support the hypothesis that the convulsant activity of these agents comes in part from selective antagonism of GABA-mediated postsynaptic inhibition.