FURTHER EVIDENCE OF INVOLVEMENT OF SUBSTANTIA-NIGRA GABA(B) RECEPTORSIN SEIZURE SUPPRESSION IN DEVELOPING RATS

To determine whether the substantia nigra GABAergic anticonvulsant eff ects depend on GABA(B) receptor activation, we tested the effects of i ntranigral CGP 35 348 (a GABA(B) receptor antagonist) alone or in comb ination with gamma-vinyl-GABA (GVG; a GABA-transaminase inhibitor) on flurothyl seizures in rat pups and adult rats. In pups, nigral infusio ns of CGP 35 348 decreased the thresholds for clonic and tonic seizure s and attenuated the anticonvulsant effects of GVG. In adults, nigral infusions of CGP 35 348 did not alter seizure thresholds. The data sug gest that, in rat pups, nigral GABA(B) receptors regulate, in part, fl urothyl-induced seizures.