Intranigral muscimol attenuates electrographic signs of seizure activity induced by intravenous bicuculline in rats.

Rats were implanted with infusion cannulas in the substantia nigra (SN), and intracranial electrodes for recording the electroencephalogram (EEG). These rats received intravenous injections of bicuculline, producing repetitive high voltage spike-and-wave complexes. Pretreatment with bilateral intranigral infusions of the GABA agonist muscimol reduced the duration of EEG epileptic activity by over 80%, as compared to the effect of pretreatment with intranigral saline in the same rats. This antiepileptic effect of intranigral muscimol may reflect a primary influence of SN outputs on brain excitability.