Effect of insulin-like growth factor I on deoxyribonucleic acid synthesis in cultured human granulosa cells

Insulin-like growth factor I (IGF-I) has been proposed to be an autocrine/paracrine factor involved in granulosa cell proliferation and differentiation. The present study focuses on a possible mitogenic effect of IGF-I in human granulosa cells. Insulin-like growth factor I (1 to 10 ng/mL) significantly stimulated 3H-thymidine incorporation in granulosa cells obtained from both natural cycles and from patients stimulated for in vitro fertilization, whereas luteinizing hormone (LH, 10 ng/mL), follicle-stimulating hormone (FSH, 10 ng/mL) and epidermal growth factor (EGF, 10 ng/mL) had no apparent effect on deoxyribonucleic acid (DNA) synthesis under these conditions. Luteinizing hormone and FSH stimulated progesterone secretion whereas IGF-I and EGF were without effect. Our observations that IGF-I stimulates DNA synthesis in human granulosa cells is in agreement with previous reports, in other species, indicating that IGF-I might be of importance for granulosa cell proliferation.