Progestogens act by binding to and activating the progesterone receptors (PRs), including the PR-A, PR-B, and PR-C. Major tissues affected by progestogens include the uterus, cervix, vagina, breasts, and brain. By activating PRs in the hypothalamus and pituitary gland, progestogens suppress the secretion of gonadotropins and thereby function as antigonadotropins at sufficiently high doses. Progesterone interacts with membrane progesterone receptors, but interaction of progestins with these receptors is less clear. In addition to their progestogenic activity, many progestogens have off-target activities such as androgenic, antiandrogenic, estrogenic, glucocorticoid, and antimineralocorticoid activity.