Regulation of steroid hormone production by the human granulosa-luteal cells

as an activin-binding protein. However, follistatin may also have direct actions on granulosa cells which are independent of its activin-binding activity. Follistatin stimulated basal progesterone and estradiol production; however, this stimulatory effect of follistatin on basal levels of steroid hormones was not present in all of the experiments. Follistatin did not affect hCG-stimulated estradiol and progesterone production by human granulosa cells. The biochemical pathways that lead to the formation ofthe Ang II/III exists in the human ovary. The effects of Ang II and Ang III with regard to steroid production in the ovary were investigated. Ang III but not Ang II inhibited hCG-stimulated progesterone production. On the other hand, Ang II stimulated basal estradiol levels while Ang III had no effect on basal or hCG-induced estradiol production. Taken together, these results suggest that Ang II and Ang III may promote follicular maturation in the human ovary by enhancing basal estradiol production from granulosa cells and preventing premature luteinization. In summary, the results from this study showed that local ovarian substances play a role in modulating the steroid hormone production by the granulosa cells. It is anticipated that future studies may allow for a better understanding of the coordinated action of many local substances involved in regulating steroid hormone production in the human ovary.Medicine, Faculty ofCellular and Physiological Sciences, Department ofGraduat