Effects of gonadotrophin-releasing hormone agonists on human ovarian steroid secretion in vivo and in vitro-results of a prospective, randomized in-vitro fertilization study.

The aim of this prospective randomized study was to compare the effects of two gonadotrophin-releasing hormone (GnRH) agonists, buserelin and triptorelin, on human ovarian follicular steroidogenesis, oocyte fertilization and IVF treatment outcome. Ovulatory, healthy women undergoing IVF were treated either with human menopausal gonadotrophin (HMG) alone or with HMG and one of the two GnRH agonists. Serum and follicular fluid hormonal concentrations and cultures of luteinizing granulosa cells obtained during follicular aspiration were analysed. GnRH agonist treatment significantly affected steroidogenesis both in serum and follicular fluid. In follicular fluid, progesterone and oestradiol concentrations were significantly elevated while testosterone concentrations were significantly lower in the triptorelin group. The ratios of testosterone/progesterone, oestradiol/progesterone but not oestradiol/testosterone concentrations were significantly affected by GnRH agonist administration. Similarly, the steroidogenic activity of luteinizing granulosa cells in vitro was significantly decreased in women treated with GnRH agonists. Women treated with GnRH agonists had significantly more fertilized oocytes and cleaving embryos. The results indicate a marked effect of GnRH agonists on the pattern of ovarian follicular steroidogenesis that cannot be explained solely by changes in gonadotrophin concentrations.