GnRH agonists initially stimulate the release of FSH and LH but eventually lead to a downregulation of GnRH receptors, resulting in decreased levels of these hormones. This creates a hypoestrogenic state, useful in conditions like endometriosis and uterine fibroids. On the other hand, GnRH antagonists provide an immediate blockade of GnRH receptors, leading to a rapid decline in gonadotropin secretion. This is often used in IVF to prevent premature ovulation.
