Inhibitory effects of endothelin-1 and endothelin-3 on prolactin release: possible involvement of endogenous endothelin isopeptides in the rat anterior pituitary.

Spontaneous prolactin release from the isolated rat anterior pituitary was inhibited by endothelin-1 in a dose-dependent manner (10(-8)-10(-6) M). Endothelin-3 also inhibited spontaneous prolactin release with an almost identical dose-response relationship as endothelin-1. These inhibitory effects were unaffected by application of a dopamine D2-receptor antagonist, YM-09151-2 (10(-7) M). Rat anterior and posterior pituitary glands were abundant in both endothelin-1 and endothelin-3, as compared with other regions of the brain. The present results suggest that endogenous endothelin-1 and endothelin-3 in the anterior and posterior pituitary are involved in the inhibitory regulation of prolactin secretion as autocrine or paracrine factors.