Inhibition of prolactin secretion in rats with the ergoline derivative deprenon

In three experimental models, (1) reserpine-premedicated male rats, (2) estrogen-premedicated female rats, (3) intact female rats, the prolactin secretion inhibiting activity was studied of the ergoline derivative D-6-methyl-8-ergolin(I)ylacetamide (deprenon). In all experiments deprenon was administered orally (by gavage), in single doses of 0.5 mg/kg to reserpine-premedicated male rats and to intact female rats, and of 0.025 mg/kg or 0.25 mg/kg, to estrogen-premedicated female rats. The animals were killed by decapitation at h 1 to 9 after administration of deprenon. The serum prolactin levels were determined by the double antibody radioimmunoassay procedure. After single oral administrations of deprenon in any of the specified doses the serum prolactin levels were depressed statistically highly significantly, both in the animals with intentionally raised serum prolactin levels and in the intact animals with physiological serum levels of the hormone. The inhibitory effect of deprenon on prolactin secretion became apparent already within 1 h, and still persisted at h 9 after administration.