FOLLISTATIN CONCENTRATIONS IN FOLLICULAR-FLUID OF NORMAL AND POLYCYSTIC OVARIES

Follistatin (FS) is an activin/inhibin binding protein which is believ ed to act in an autocrine/paracrine manner to regulate growth and diff erentiation. Although FS has been identified in human follicular fluid , it remains unclear how its concentration changes during selection an d atresia, and what the concentrations of FS are in follicles of women with polycystic ovary syndrome (PCOS). Towards this goal, we have mea sured by radioimmunoassay the concentrations of FS in follicular fluid obtained from dominant and atretic cohort follicles of normal cycling women, preovulatory follicles of in-vitro fertilization (IVF) patient s, and small Graafian follicles of patients with PCOS, In all cases, t he follicular fluid concentration of FS was much higher (similar to 10 0-fold) than that reported in serum, The FS concentrations (ng/ml) wer e 203 +/- 42 (normal dominant), 185 +/- 17 (atretic cohort), 185 +/- 5 (IVF), and 250 +/- 14 (PCOS), There was no statistical difference bet ween these mean values of FS, Further, there were no significant corre lations between the follicular fluid concentrations of FS and the conc entrations of oestradiol, progesterone, or androstenedione, These resu lts indicate that human Graafian follicles, regardless of whether they are healthy or atretic, normal or PCOS, contain high steady-state con centrations of FS in the micro-environment. Collectively, these data f it with the hypothesis that major increases and decreases in the conce ntration of FS in the micro-environment may not play a key role in the mechanisms of selection, atresia, and PCOS in women. The possibility of regulation of intrinsic activin and inhibin activity through FS bin ding is discussed.