Angiotensin II modulates steroidogenesis in granulosa and theca in the rabbit ovary: its possible involvement in atresia

Féral C, Le Gall S, Leymarie P. Angiotensin II modulates steroidogenesis in granulosa and theca in the rabbit ovary: its possible involvement in atresia. Eur J Endocrinol 1995;133:747–53. ISSN 0804–4643 Accumulating evidence has shown the ovary of mammals to contain an intrinsic renin–angiotensin system that has been ascribed an autocrine-paracrine role. The present study in the female rabbit ovary investigated the putative in vitro action of angiotensin II (A II) on basal and gonadotropin-induced steroidogenesis. Ovarian follicles from immature female rabbits treated with pregnant mare's serum gonadotropin (PMSG) were dissected out and a complete separation of the theca interna from the granulosa layer was performed, to demonstrate that A II affects separately the two individual cellular components of the follicular wall. We could show that theca is a source of estradiol whose production under human chorionic gonadotropin (hCG) stimulation was reduced by A II. At the same time, A II increased the in vitro hCG-stimulated secretion of testosterone by theca. In granulosa, A II decreased hCG-stimulated aromatization of androstenedione to estradiol but did not alter the release of hCG-stimulated progesterone production. These results suggest that A II could induce locally an increase in follicular fluid androgen/estrogen ratio and possibly participate in causing atresia. C. Féral, EP CNRS 009, Laboratoire de Biochimie, CHU Caen, F-14032 Caen Cedex, France