Insulin-like growth factor binding proteins in a natural pre-ovulatory follicle from a woman with polycystic ovary syndrome.

Insulin-like growth factor binding protein (IGFBP) concentrations in the follicular fluid of ovarian follicles have been shown to correlate with dominance and atresia. IGFBP-2 and IGFBP-4 are increased in atresia, and IGFBP-3 is decreased in dominant follicles. The purpose of this study was to compare the IGFBP concentration in follicular fluid from a natural pre-ovulatory follicle of a woman with polycystic ovarian syndrome (PCOS) with other PCOS follicles and dominant follicles from normally cycling women. Follicular fluid was collected from 5-7 mm diameter follicles and a natural pre-ovulatory follicle from women with PCOS, and healthy and atretic follicles from normal women. The IGFBP profiles were analysed using Western ligand blotting. The IGFBP concentrations in the 5-7 mm diameter follicles from the polycystic ovaries containing a pre-ovulatory follicle were similar to those in follicles from other women with PCOS, and comparable with androgenic cohort follicles from normal women. In particular, the IGFBP-2 and IGFBP-4 concentrations were elevated significantly compared with the oestrogenic cohort follicles. The concentrations of all IGFBP detected in the follicular fluid from the PCOS pre-ovulatory follicle were significantly less than those of the 5-7 mm diameter follicles from the same subject. The IGFBP concentrations were within the range of normal dominant follicles, and IGFBP-2 and IGFBP-3 were at the lower end of the normal range. The results indicate that the PCOS pre-ovulatory follicle contained a normal pattern of IGFBP expression even though the other follicles exhibited a pattern typical of PCOS. These data support the hypothesis that decreased concentrations of IGFBP, in particular IGFBP-3, may be involved in selection of the dominant follicle, and that when a spontaneous pre-ovulatory follicle develops in PCOS, the underlying cause of the polycystic ovaries is not resolved but the rest of the ovary remains polycystic.