Immunocytochemical localization of angiotensin II immunoreactivity and demonstration of angiotensin II binding in the rat ovary.

The cellular localization of angiotensin II immunoreactivity and the presence of angiotensin II binding in rat ovaries were studied. Angiotensin II immunohistochemical staining was demonstrated throughout the corpora lutea of gonadotropin-stimulated immature rats and pseudopregnant adult rats, as well as in some stromal and thecal cells surrounding large antral follicles. No immunostaining was observed in granulosa cells of preantral or antral rat follicles or in ovaries from unstimulated immature rats. With in vitro autoradiography, specific, saralasin-suppressible 125I-angiotensin II binding was demonstrated in normal cycling rat ovaries: diestrus greater than proestrus greater than estrus. The combined findings of angiotensin II immunostaining in ovarian follicles and corpora lutea and of cycle-related angiotensin II binding support the hypothesis of a functional role for the ovarian renin-angiotensin system.