Angiotensin II: a reproductive hormone too?

It has long been known that angiotensin II (Ang II) can affect reproductive tissues such as the uterus. However, the existence of a local renin-angiot ensin system (RAS) in female as well as male reproductive tissues is a rela tively recent observation. Of great interest is the discovery that all comp onents of the RAS are present in the ovary, that the ovary secretes compone nts of the RAS into the bloodstream, and that the ovary itself is responsiv e to Ang II. Recent studies suggest that the primary role of Ang II in the ovary is to cause atresia in non-ovulatory follicles; however, there is als o compelling data to suggest that Ang II facilitates ovulation. Male reprod uctive structures also contain all of the components of the RAS, gonadotrop ins regulate the activity of these components, and these tissues have Ang I I receptors. Of great interest is the expression of testis-specific angiote nsin-converting enzyme (ACE), which is located on germ cells. Recent studie s using gene knock-out techniques indicate that testis ACE plays an importa nt role in male fertility. However, the overall significance of the RAS for normal reproductive function remains questionable. There is now a body of evidence implicating the RAS in pathophysiologies associated with reproduct ive function, which gives rise to the possibility that drugs acting on the RAS might ameliorate some of these disorders. Considerable work remains to determine the role of Ang II in reproductive functions. (C) 1999 Published by Elsevier Science B.V. All rights reserved.