Monoamine release in the rat striatum is induced by delta-guanidinovaleric acid and inhibited by GABA agonists

delta-Guanidinovaleric acid (GVA) is an endogenous convulsant and is thought to be a specific gamma-aminobutyric acid (GABA) antagonist. In this study, we examined the effects of GVA and GABA agonists, GABA, muscimol and baclofen, on the release of dopamine (DA) and serotonin (5-HT) in the rat striatum using a brain dialysis technique. GVA produced a significant increase in the amount of DA and 5-HT released compared with controls. Both GABA (10mM) and muscimol (10mM) inhibited the GVA-induced release of DA and 5-HT. Muscimol was a more potent inhibitor of 5-HT release than DA release. Baclofen (10mM) inhibited only the GVA-induced DA release. These results suggest that the activation of GABA receptors inhibits the release of DA and 5-HT in the striatum, and that the dopaminergic system regulates GABA-B receptors and the serotonergic system mainly regulates GABA-A receptors.