Angiotensin II stimulates prolactin release in the rhesus monkey

The effect of angiotensin II (AII) on plasma prolactin (PRL) concentrations was evaluated in ovariectomized rhesus monkeys which had been conditioned to chair restraining. Intracerebro-ventricular (i.v.t.) microinjections of AII increased PRL plasma levels in a dose-dependent manner. PRL values peaked at 10 min after injection and declined rapidly thereafter. Peak levels of PRL after 50 micrograms AII were approximately 7 times higher than those of baseline controls and were significantly reduced when 500 micrograms saralasin were injected via the ventricular route 15 min before AII injections. Measurements of vasopressin (AVP) plasma levels in some experiments showed that AVP release occurred following any dose of AII, irrespective of PRL liberation. In 2 animals, central injections of AII induced a dose-related increase in blood pressure. This study shows that, in primates, AII is able to influence PRL secretion via specific AII receptors. This action of AII is independent of AVP release and may be indirectly mediated through vasoactive effects of the octapeptide.