INSULIN-LIKE GROWTH-FACTOR (IGF)-I AND IGF-II STIMULATE PROGESTERONE PRODUCTION BY HUMAN LUTEAL CELLS - ROLE OF IGF-I AS MEDIATOR OF GROWTH-HORMONE ACTION

Objective: To examine the possible direct effect of insulin-like growt h factor (IGF)-I and IGF-II on basal and hCG-stimulated P production b y cultured human luteal cells. The possible role of IGF-I as mediator of GH action on luteal steroidogenesis also was investigated. Design: Cultures of human luteal cells from early and midluteal phase. Setting : All corpora lutea were obtained from the Obstetrics and Gynecology D epartment of the Universita Cattolica, a public care center. Patients: Eight nonpregnant women between 35 and 47 years of age underwent surg ery for various nonendocrine disorders such as leiomyomatosis. Interve ntions: Corpora lutea were obtained at the time of hysterectomy. Main Outcome Measures: Luteal cells were incubated with IGF-I or IGF-II wit h or without hCG at different concentrations. Growth hormone also was used alone and with an anti-IGF-I-antibody. Results: We found that IGF -I and IGF-II were able to stimulate directly the P production at all used concentrations and that both of them significantly amplified the steroidogenic hCG effect. Finally, IGF-I was shown to mediate the posi tive GH action on P synthesis.