Prostaglandin F2 alpha stimulates release of insulin-like growth factor binding protein-3 from cultured human granulosa-luteal cells.

Human ovarian follicular fluid contains a number of insulin-like growth factor binding proteins (IGFBP) of which IGFBP-3 is the most abundant. IGFBP-3 synthesis is growth hormone-regulated. We studied the effect of prostaglandin F2 alpha (PGF2 alpha) on IGFBP-3 secretion by cultured human granulosa-luteal cells from follicular aspirates of women participating in an in-vitro fertilization programme. The IGFBP-3 concentration was measured using a specific monoclonal immunofluorimetric assay. Contrary to a previous report on unstimulated follicles, this study demonstrated a positive correlation between follicular fluid IGFBP-3 concentration and follicular size. PGF2 alpha was found to stimulate in a dose-dependent fashion the secretion of IGFBP-3. Significant (P < 0.05) effects were found at PGF2 alpha concentrations of 10(-8), 10(-7) and 10(-6) M. Because IGFBP-3 inhibits progesterone production stimulated by insulin-like growth factor (IGF)-I, the PGF2 alpha-induced stimulation of IGFBP-3 production may be one of the mechanisms whereby PGF2 alpha exerts its luteolytic effect via the IGF system.