Studies on the Mechanism of the GABA-Mediated Inhibition of Prolactin Secretion

Abstract

Gaba has a direct inhibiting effect on prolactin release by the pituitary in vitro and this effect is not blocked by coincubation with the specific GABA-receptor antagonist picrotoxin. GABA appears to be at least 100-fold less potent than dopamine as an inhibitor of prolactin secretion. Systemic administration of GABA did not affect basal serum prolactin levels, but inhibited the 5-hydroxytryptophan-induced secretion of prolactin. Apparently, the direct effect of GABA on prolactin secretion by the pituitary is not mediated by well-defined neurotransmitter mechanisms.