THE EFFECTS OF BICUCULLINE (A GABA(A) RECEPTOR ANTAGONIST) ON LHRH-A AND PIMOZIDE STIMULATED GONADOTROPIN (GTH2) RELEASE IN FEMALE CARP (CYPRINUS-CARPIO L)

The y-aminobutyric acid (GABA) receptor antagonist, bicuculline (BIC), LHRH-A and pimozide (a dopamine receptor antagonist, PIM) were admini stered to mature females carp in order to test the hypothesis that BIC , like PIM, may modulate the action of endogenous dopamine (DA) at the pituitary level. Experiments conducted in two consecutive spawning se asons have shown that BIC potentiates the LHRH-A-stimulated release of GtH2. The lack of differences in GtH2 levels between the groups stimu lated with LHRH-A in the presence of PIM or BIC suggests that BIC, lik e PIM, modulates the action of endogenous DA at the pituitary level. T hese data indirectly support the idea that GABA may affect GtH2 releas e via DA-ergic system.