Insulin-Like Growth Factors, Insulin-Like Growth Factor Binding Proteins and Ovarian Androgen Production

Increasing evidence indicates that the ovary contains an insulin-like growth factor (IGF) system complete with ligands, binding proteins, and receptors. Through their interaction with IGF receptors on theca-interstitial cell surface membranes, the ligands, IGF-I and IGF-II, synergize with luteinizing hormone (LH) to increase ovarian androgen production. The actions of these growth factors are modulated by intraovarian binding proteins, especially IGFBP-1, IGFBP-2, and IGFBP-3, that enhance or inhibit the biological actions of the IGFs. These observations suggest that the IGF system plays a role in normal ovarian function and in the pathophysiology of ovarian hyperandrogenism and polycystic ovary syndrome.