AT2 Receptor Expression in Ovaries: A Review

All the components of the renin-angiotensin system (RAS) have been demonstrated in the mammalian ovary, indicating the existence of a functional local tissue RAS (1,2). The activity of the ovarian RAS increases during pregnancy, in relation to ovulation, and during stimulation of oocyte maturation and ovulation with gonadotropins as reflected by markedly increased prorenin concentrations in plasma (3,4,5). In accordance, Einspanier et al. (6) have demonstrated a pulsative angiotensin (Ang) II secretion in ovarian follicles and corpora lutea of freely moving pigs with the highest average secretion in the periovulatory period by using implanted microdialysis systems. Several studies have suggested effects of the ovarian RAS on oocyte maturation, ovulation, steroidogenesis and angiogenesis, but the functional roles of the ovarian RAS are not fully clarified. Since the effects of the ovarian RAS are mediated by Ang II receptors, the expression of these receptors and their intracellular messenger systems are of major interest. This paper reviews some of the data on the expression and functional roles of Ang II receptors in ovaries.