beta-Endorphin release by angiotensin II: studies on the mechanism of action.
Blood-borne angiotensin II induces release of beta-endorphin-like immunoreactivity (beta-EI) from rat anterior pituitary gland. To study the mechanism of action we investigated in rats the effect of transection of subfornical organ efferent projections on angiotensin-induced beta-EI release in vivo and also the direct action of angiotensin II on beta-EI release from isolated adenohypophyses in vitro. (i) No effect of transection of subfornical organ efferents on the increase in plasma beta-EI following intravenous infusions of angiotensin II was found. (ii) When anterior pituitary quarters were continuously superfused in vitro, angiotensin II (1-10 nM) caused release of beta-EI into the superfusion medium in a dose-dependent manner. The stimulatory effect of angiotensin II (3 nM) was blocked by the receptor antagonist saralasin (300 nM). We conclude that beta-endorphin release by blood-borne angiotensin II, in contrast to other central effects of angiotensin, is not mediated by the subfornical organ; instead a direct action of angiotensin II on the adenohypophysis could be a mechanism of action responsible.
D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D001127:Arginine Vasopressin / Q000378:metabolism; D004525:Efferent Pathways / Q000502:physiology; D004723:Endorphins / Q000378:metabolism*; D008297:Male; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors; D001615:beta-Endorphin
D004723:Endorphins; D000804:Angiotensin II; D001127:Arginine Vasopressin; D001615:beta-Endorphin