Gonadotropins induce higher active renin levels in the follicular fluid ofnormal and hyperstimulated cycles

The objective of this study was to analyse follicular fluid active renin;an d its relationship to steroid hormones throughout the normal and gonadotrop in-stimulated menstrual cycle. Active renin was measured in the follicular fluid of patients undergoing tubal sterilization (n = 16) and in vitro fert ilization (IVF) (n = 25); IVF patients were either in a natural cycle (n;= 7) or undergoing controlled ovarian hyperstimulation (n = 18). The largest visible follicle was aspirated at the time of laparoscopic tubal sterilizat ion; ultrasound guided transvaginal follicular aspiration was used in the I VF group. Follicular fluid active renin, estradiol and progesterone levels were measured with immunoradiometric and fluoroimmunoassays. The cycle day was correlated with the spontaneous luteinizing hormone (LH) surge or human chorionic gonadotropin (hCG) administration, as well as active renin, estr adiol, progesterone levels and the estradiol/ progesterone ratio using simp le and multiple regression and analysis of variance (ANOVA). Cycle day inde pendently influenced active renin, progesterone and the estradiol/progester one ratio in a statistically significant manner (p < 0.0001). The active ve nin and progesterone levels were highest during the periovulatory period (p < 0.0001 and p < 0.002, respectively) and the estradiol/progesterone ratio correlated inversely with cycle day (p < 0.003). Although the follicular f luid active venin, estradiol and progesterone levels were higher after cont rolled ovarian hyperstimulation when compared to natural cycles, this diffe rence did not reach statistical significance. Our findings suggest that act ive renin levels in follicular fluid increase in the follicular phase of th e menstrual cycle, reaching peak levels in the periovulatory period followi ng the LH surge or hCG administration, providing indirect support for the h ypothesis that the ovarian renin-angiotensin system (RAS) is under gonadotr opin control.