Pituitary gonadotropins are generally viewed as the principal regulators of ovarian function; however, there is increasing evidence to suggest that insulin and insulin-like growth factors (IGFs) may play an important role in regulation of ovarian physiology. The objective of the research is to examine these regulatory mechanisms. The studies will include in vitro experiments with human ovarian tissue as well as in vivo animal experiments. Human ovarian tissue will be obtained during indicated surgical procedures and separated into stromal and follicular compartments; granulosa cells obtained in the course of in vitro fertilization will be purified using Percoll gradients. Receptors for insulin and insulin-like growth factors will be characterized by binding studies with the use of specific antireceptor antibodies. Their regulation by insulin, IGFs, LH and FSH, as well as changes in receptor status in the course of follicular maturation, will be assessed. Effects of insulin and IGFs alone, as well as in combinations with each other, LH, or FSH, on steroidogenesis will be studied using short-term tissue culture of human granulosa cells. Attempts to establish a hormonally active cell line using explants of human stromal and thecal tissue, as well as human granulosa cells, will be made. In vivo experiments will examine effects of chronic hyperinsulinemia, produced in female rats, on ovarian steroidogenesis. These studies will improve our understanding of such diverse conditions as ovarian dysfunction in women with diabetes, obesity and insulin-resistant states, polycystic ovarian disease and infertility. Better insights into these entities will hopefully lead to the development of more successful therapeutic regimens.