Suppression of methionine sulfoximine seizures by intranigral γ-vinyl GABA injection

Studies were undertaken to determine whether enhancement of GABAergic transmission within the substantia nigra could inhibit seizures caused by the novel, long latency convulsant, L-methionine, sulfoximine (MSO; 200 mg/kg i.p.). Bilateral injections of γ-vinyl GABA (10 μg/side) into several brain sites resulted in varying degrees of protection against MSO-induced seizures. However, significant protection was afforded only when γ-vinyl GABA was infused into the nigra. The protective effect was reduced when injections were made at sites 2 mm dorsal to the nigra, and was further diminished when the drug was injected into the striatum. These results further support the hypothesis that elevation of cerebral GABA levels is protective against a range of experimentally induced seizures, particularly when the substantia nigra is the target of such manipulations.