Neuroethological evaluation of audiogenic seizures and audiogenic-like seizures induced by microinjection of bicuculline into the inferior colliculus. II. Effects of nigral clobazam microinjections.

Male Wistar rats were classified as susceptible (S) and resistant (R) to audiogenic seizures (AS) by evaluation of their response to high-intensity sound stimulation (110.3 dB). R rats injected with bicuculline into the inferior colliculus (IC) preferentially displayed audiogenic-like seizures with gyri, jumping and atonic falling, without important tonic-clonic components but with postictal contralateral asymmetry and hyperreactivity. These audiogenic-like seizures were blocked by clobazam microinjection into the substantia nigra (SN) and partially modified by SN vehicle injection. Injection of vehicle or clobazam into the SN of susceptible rats (S) did not modify the occurrence of AS. This may suggest the participation of GABAergic regulation in the development of audiogenic-like seizures in R rats and a defect in GABAergic neurotransmission in S rats.