Effects of unilateral microinjections of GABAergic drugs into the inferior colliculus on auditory evoked potentials and on audiogenic seizure susceptibility.

Alteration of GABAergic neurotransmission within the inferior colliculus (IC) appears to be involved in the generation of the audiogenic seizure (AGS) susceptibility. In the present study, we provide evidence indicating that this susceptibility may result from IC neuronal hyperexcitability to sound induced by a decreased GABAergic inhibition. In a first experiment, a unilateral microinjection of bicuculline, a GABAa antagonist, into the IC of normal rats increased the amplitude of the collicular auditory evoked potential, while the microinjection of THIP, a GABAa agonist, decreased this response. In a second experiment, a unilateral microinjection of bicuculline into the IC induced AGS susceptibility in normal rats.