ANDROGEN INDUCED DYSFUNCTION IN THE BOVINE OVARY

Anovulation with or without the presence of cystic ovarian follicles is a significant cause of reproductive dysfunction in cattle. Environmental factors such as heat stress, feed quality and hormonal imbalances all contribute to reduced reproductive efficiency. Follicular development, ovulation and luteinization are controlled by many hormonal signals and by an array of complex intrafollicular mechanisms that regulate both somatic and germ cell development. Interactions among ovarian cells includes both direct cell-cell contacts, indirect cell-ECM contacts and signaling through secreted products. Androgens are among the most abundant signals produced in the bovine ovary. Exposure to high androgen levels causes follicular cysts, anovulation, and reduced fertility in several mammalian species. Cattle with very high follicular androgen levels are less fertile and have altered ovarian function. However, we do not fully understand how excessive androgen stimulation leads to ovarian dysfunction. We hypothesize that overactivation of the androgen membrane receptor ZIP9 will lead to ovarian fibrosis, altered gene expression and impaired ovarian function. This hypothesis will be tested with a combination of in vitro culture of ovarian cells, intact follicles and ovarian explants treated with various androgenic compounds. The results will uncover the consequences of excessive androgen stimulation on ovarian function and could lead to better ways to mitigate these effects to improve reproductive efficiency in cattle.