Direct gonadotrophic effect of growth hormone on oestradiol production by human granulosa cells in vitro.

In-vitro studies in both rodents and man suggest that GH can stimulate ovarian steroidogenesis, but it is not clear whether this effect is mediated by changes in circulating concentrations of insulin-like growth factor-1 (IGF-1) or whether it is a direct action on the ovary (or, indeed, both). In this study the effects of biosynthetic human GH (hGH) on the production of oestradiol and IGF-1 by human granulosa cells in culture were examined using ovarian tissue (from both normal and polycystic ovaries) which had not previously been exposed to exogenous gonadotrophin therapy. Addition of hGH (1 or 10 ng/ml) to the incubation medium resulted in a significant (1.7 to 3.6 fold) increase in oestradiol accumulation after 48h in culture. Human GH also had a significant additive effect on the dose-related responsiveness of granulosa cell oestradiol production to hFSH. Concentrations of IGF-1 in the medium were undetectable in each of these experiments. These studies demonstrate that hGH has a potent, direct stimulatory effect on production of oestradiol by the human ovary which is independent of the effect of FSH. These findings have important implications for understanding the physiological role of hGH in human ovarian function as well as for therapeutic use of biosynthetic hGH for induction of ovulation.