IGF-I and EGF influence on steroid secretion and morphology of human granulosa cells of IVF-cycles and natural cycles in vitro.

The effect of IGF-I, EGF, PDGF and FGF on human granulosa cells of IVF-cycles, and the effect of IGF-I on granulosa cells of natural cycles (day 7 to 13 of cycle) were evaluated in vitro with and without hCG stimulation. At concentrations of 1 ng and 5 ng per ml culture FGF and PDGF did not alter progesterone and estradiol secretion or the morphology of preovulatory granulosa cells. At 1 ng, 2 ng, and 3 ng per ml medium EGF significantly enhanced basal progesterone and estradiol secretion and significantly decreased hCG stimulated estradiol production of preovulatory granulosa cells. While IGF-I treatment with and without hCG stimulation did not alter steroid secretion of preovulatory granulosa cells, the progesterone secretion of granulosa cells of natural cycles was increased by combined treatment with 10 I.U. hCG + 25 ng IGF-I per ml culture medium. Increased steroid secretion was related to reduced cell spreading. Our results provide evidence for the facultative role of IGF-I and EGF as an autocrine/paracrine modulator of ovarian function. IGF-I may play a role in regulation of ovulation induction and luteinisation as IGF-I and hCG act synergistically in increasing progesterone secretion of granulosa cells of natural cycles in vitro and are known to stimulate each other's receptor expression.