Endocrinology:iMmunohistochemical localization of growth hormone receptor in cyclic human ovaries

It has been demonstrated that co-administration of growth hormon (GH) augments ovarian response to human menopausal gonadotrophin, and GH itself increases steroidogenesis in cultured ovarian cells. It is not clear, however, whether the effects of GH on the ovary are direct or not. We performed immunohistochemistry using specific monoclonal antibodies against human GH receptor on 51 specimens of pre-menopausal human ovaries from various phases of the menstrual cycle to detect and localize GH receptors. Immunohistochemical localization of P450 aromatase and 3β-hydroxysteroid dehydrogenase was performed using these enzymes as immunohistochemical markers for steroidogenesis in these ovaries. GH receptor immunoreactivity was observed in luteinized granulosa cells in corpora lutea in the luteal phase, which are considered to be active in steroid production. In the follicular phase, GH receptor immunoreactivity was detected in the granulosa layer of only three out of 35 antral follicles. These results demonstrate that immunoreactivity of GH receptor is present in human ovaries, suggesting a direct action of GH on human ovarian functions, especially during luteal phase.