Epidermal Growth Factor Modulation of Gonadotrope Function

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9724066 Childs Epidermal growth factor (EGF) is produced mainly by pituitary gonadotropes or growth hormone cells. All pituitary cell types have receptors for EGF as well, which suggests that this growth factor is an important regulator in the pituitary. This study will focus on possible regulator roles for EGF in the reproductive system, specifically in controlling pituitary gonadotropes. The first objective will be to test the hypothesis that EGF regulates cell division in gonadotropes. This will be done with cell growth assays on cultures of purified gonadotropes (enriched to 90-95% gonadotropes). Cytochemical assays will also be used to prove that the gonadotropes are dividing. The second objective will be to learn if EGF affects differentiation of gonadotropes during diestrus as the cells are being prepared for the enhanced secretory activity needed for ovulation. Studies for this second objective will also test EGF effects on the gonadotrope expression of estradiol receptors. EGF receptors appear on 60% of gonadotropes before the estradiol receptors. The PI will test the hypothesis that EGF works trough the EGF receptors to stimulate theh expression of estradiol receptors. Progress in the field has already shown that EGF is important to the reproductive system as a growth factor. It promotes the development and function of cells in both the gonads and the hypothalamus. Little is known about its role in the pituitary, however. This study is one of the few studies in the world that will define its role in the regulation of pituitary gonadotropes during the estrous cycle.