Angiotensin-(1-7), Angiotensin-Converting Enzyme 2 and Mas Receptor in Rat Polycystic Ovaries

BACKGROUND: Hyperandrogenism is a pivotal mediator in the pathogenesis of the polycystic ovary syndrome (PCOS), but the mechanisms of androgen excess in this condition are not fully understood. Angiotensin (Ang)-(1-7) is an active peptide of the renin-angiotensin system (RAS) that stimulates ovarian follicular growth and testosterone release in vitro. OBJECTIVE: To investigate whether Ang-(1-7), its receptor Mas and angiotensin-converting enzyme 2 (ACE2), the enzyme that converts Ang II into Ang-(1-7), are expressed in rat polycystic ovaries (PCO) and thus if this peptide system might be associated with excess androgen production in PCO. METHODS: A rat model that shares some features of PCOS such as disruption of folliculogenesis and multiple ovarian cyst formation was used in the study. RESULTS: We found reduced levels of Ang-(1-7) and Mas receptor in PCO compared to normal ovaries. Also, ACE2 mRNA expression was reduced in PCO compared to ovaries of control rats (p < 0.05). PCO had high levels of estrogen and testosterone and increased mRNA for upstream enzymes of the steroidogenic cascade, but not of P450 aromatase. CONCLUSION: These findings suggest that the ovarian ACE2-Ang-(1-7)-Mas receptor axis is inhibited and therefore may not be a co-factor of excess testosterone production in rat PCO.