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, an d receptors. Through their interaction with IGF receptors on theca-int erstitial cell surface membranes, the ligands, IGF-I and IGF-II, syner gize with luteinizing hormone (LH) to increase ovarian androgen produc tion. The actions of these growth factors are modulated by intraovaria n binding proteins, especially IGFBP-1, IGFBP-2, and IGFBP-3, that enh ance or inhibit the biological actions of the IGFs. These observations suggest that the IGF system plays a role in normal ovarian function a nd in the pathophysiology of ovarian hyperandrogenism and polycystic o vary syndrome.