Gonadotropin-releasing hormone (GnRH) agonists are routinely used to suppress the reproductive axis of many mammals, especially in zoos. Current treatments are reversible. There is a need to develop nonreversible agents, and this study investigates the effects of high-dose and long-duration exposure to the GnRH agonist, deslorelin, in the rat model. Studies indicate that the follicle-stimulating hormone (FSH) gonadotropin is predominantly affected, and following high-dose exposure to deslorelin for a long duration, the ability of gonadotropes to synthesize FSH may be compromised, perhaps permanently. Understanding the mechanisms by which such persistent suppression of FSH occurs may facilitate the development of novel next-generation contraceptives. It is hypothesized that direct testicular effects of GnRH agonists may play a critical role in the efficacy of GnRH agonists in male contraception.