A GABA-B-RECEPTOR MECHANISM IS INVOLVED IN THE PROLACTIN-RELEASE IN BOTH MALE AND FEMALE RATS

In order to evaluate the possible involvement of a GABA(B)-receptor mechanism in the control of prolactin release, the effect of baclofen, a GABA(B)-receptor agonist, on prolactin release was studied in male and female rats. Baclofen at a dose of 2-12 mg/kg was injected i.v. and blood samples were collected through an intraatrial cannula in freely moving rats. Baclofen caused an immediate increase in the prolactin concentration in serum, peaking at 6 min, in female rats. The injection also caused an increase in prolactin in male rats, the increase being smaller than in female rats. Together with the previous finding that the pituitary gland does not have GABA(B) receptors, the results support the concept that GABA plays a role in the central stimulation of prolactin release, mediated by GABA(B) receptors.