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 me chanism in the control of prolactin release, the effect of baclofen, a GABA(B)-receptor agonist, on prolactin release was studied in male an d 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 co ncentration 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 t he pituitary gland does not have GABA(B) receptors, the results suppor t the concept that GABA plays a role in the central stimulation of pro lactin release, mediated by GABA(B) receptors.