GNRH1 and hyperprolactinemia: Chronic hyperprolactinemia in rats reduced the level of gonadotrophin-induced E2 production in antral follicles (Jonassen et al., 1991), and hyperprolactinemia in women inhibits GnRH contributing to altered cyclicity, ovulatory failure, and infertility (Bachelot and Binart, 2007).