Augmentation by thyroxine of human granulosa cell gonadotrophin-induced steroidogenesis

The objective of this study was to investigate the influence of thyroid hormone on gonadotrophin-induced oestradiol and progesterone secretion by human granulosa cells maintained in vitro. Granulosa cells were obtained by aspiration of pre-ovulatory follicles from women undergoing assisted reproductive technology. Ovulation induction was performed with gonadotrophin-releasing hormone agonist, human menopausal gonadotrophin and human chorionic gonadotrophin. Granulosa cells were maintained in vitro in a defined medium with added insulin. Between 48 and 72 h after the initiation of cell culture, oestradiol and progesterone secretion into the medium was determined for granulosa cells growing in serum-free medium with follicle-stimulating hormone (FSH)/luteinizing hormone (LH) and in serum-free medium with FSH/LH and thyroxine added in a concentration range of 10(-10)-10(-7) M. All concentrations of thyroxine used produced a statistically significant increase in oestradiol (range 1.18-1.37 times the amount with FSH/LH alone) and progesterone (range 1.29-1.51 times the amount with FSH/LH alone) secretion.