Effects of angiotensin II on sexual function, blood pressure, and fluid intake are differentially affected by AT-1 receptor blockade.

We have previously reported that third ventricular administration of angiotensin II (ANG II) immediately before mating tests suppressed copulatory behavior in male rats. The present studies examine the effects of short- (3 days) and long-term (21 days) intracerebroventricular (i.c.v.) infusion of ANG II (6 microg/h), on parameters of copulatory behavior, fluid intake, and blood pressure in sexually experienced male Long Evans rats. Further, to test the hypothesis that suppression of masculine copulatory behavior by ANG II involves interaction with the angiotensin AT-1 receptor, a highly selective nonpeptide antagonist (L-158,809) was administered in the drinking water (25 mg/liter) to a group of ANG II-infused animals. I.c.v. infusion of ANG II was associated with increases in systolic blood pressure and fluid intake. In copulatory tests after 3, 9 and 15 days of infusion, rats infused with ANG II exhibited increased latencies to the initiation of copulatory behavior and to ejaculation, as well as increased intervals to reinitiate copulatory behavior after the ejaculation. Administration of L-158,809 blocked the effects of i.c.v. infusion of ANG II on systolic blood pressure and fluid intake. Further, L-158,809 attenuated the effects of i.c.v. infusion of ANG II on parameters of copulatory behavior. Data from this study provide support for a modulatory role for ANG II in the regulation of sexual behavior. In addition, this regulation seems to involve the AT-1 receptor.