Biphasic Effects of Catecholamines on Pituitary Prolactin Release in Vitro

The in vitro effects of epinephrine, norepinephrine and dopamine on prolactin release by the rat pituitary were studied in a 4-hr incubation system. The addition of 10 or 20 ng of epinephrine or norepinephrine to 1 ml of a physiological medium containing ½ male rat pituitary significantly increased prolactin release, whereas doses of 200–1000 ng markedly inhibited prolactin release. Incorporation of 2–40 ng of dopamine into the medium had no effect, whereas 80–640 ng significantly decreased prolactin release. These results indicate that the effects of catecholamines on pituitary prolactin release in vitro are dose dependent. (Endocrinology87: 673, 1970)