Inhibin A, inhibin B and activin A concentrations in follicular fluid from women with polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is characterized by arrestedfollicle development at the early antral stage. Alterationsin inhibin production by developing follicles could be involvedin PCOS by suppressing follicle stimulating hormone concentrationsduring the follicular phase of the menstrual cycle as well asby increasing thecal androgen production. Inhibin B appearsto be more important than inhibin A during the follicular phase;however, there are no data regarding the follicular fluid concentrationsof inhibin B in PCOS. The purpose of this study was to compareinhibin A, inhibin B and activin A concentrations in the follicularfluid from regularly cycling women and women with PCOS. InhibinA, inhibin B and activin A were measured in the follicular fluidof 4–7 mm follicles from PCOS ovaries and size-matchedfollicles from normally cycling women by specific and sensitivetwo-site enzyme-linked immunosorbent assays. In both controland polycystic ovaries, inhibin B was approximately 10-foldhigher than activin A and more than 100-fold higher than inhibinA. There was no difference in activin A concentrations betweenPCOS and control follicles. In control ovaries, the inhibinB and inhibin A concentrations in dominant follicles were significantlyhigher than in cohort follicles. While inhibin A concentrationswere lower in PCOS follicles than in normal cohort follicles,there was no difference in inhibin B concentrations betweenPCOS follicles and normal cohort follicles. These data are consistentwith the concept that inhibin B is the physiologically mostimportant form of inhibin during the follicular phase of themenstrual cycle and indicate that PCOS is not associated withincreased inhibin B concentrations in follicular fluid.