Effects of danazol on gonadotropin secretion after ovariectomy in rats

Danazol: endocrine pharmacology and therapeutic applications

The options for the medical management of endometriosis have been expanded by the introduction of the synthetic steroid, danazol. The results of large clinical studies suggest that danazol treatment produces significant improvement in the symptoms, signs, and laparoscopic findings of endometriosis. The original studies of the pharmacology of danazol concluded that danazol was a strong antigonadotrophin with mild androgenic effects and no other hormonal properties. Recent studies which emphasize the molecular pharmacology of danazol suggest that this steroid has direct effects on hypothalamic-pituitary function, multiple classes of steroid receptors, gonadal steroidogenesis, and endogenous steroid metabolism. These studies demonstrate that: (1) danazol prevents the midcycle surge of luteinizing hormone (LH) and follicle-stimulating hormone (FSH); (2) danazol does not significantly suppress basal LH or FSH in gonadally intact human beings; (3) in castrated animals danazol can prevent the compensatory increase in LH and FSH; (4) danazol binds to androgen, progesterone, and glucocorticoid receptors; (5) danazol does not bind to estrogen receptors; (6) danazol binds to sex hormone-binding globulin and corticosteroid-binding globulin; (7) danazol inhibits multiple enzymes of steroidogenesis; (8) danazol increases the metabolic clearance rate of progesterone; and (9) metabolites of danazol are hormonally active. Given the complex pharmacology of danazol it is inappropriate to continue to refer to danazol as a "selective antigonadotrophin."U

Danazol suppression of luteinizing hormone secretion: a role for danazol-androgen receptor interaction within the brain-pituitary complex

We investigated the relationship between intracellular androgen and estrogen receptors within the brain-pituitary complex and danazol suppression of luteinizing hormone secretion in castrated rats. Danazol did not influence 3H-estradiol-estrogen receptor interactions within the brain and pituitary but did suppress 3H-dihydrotestosterone-androgen receptor interactions within this neuroendocrine complex. To study the significance of these danazol-androgen receptor interactions, the drug was administered to androgen receptor-deficient pseudohermaphrodite or flutamide-treated male rats. In both instances, danazol suppression of luteinizing hormone release was markedly attenuated or absent. These findings point to danazol-androgen receptor interactions within the brain-pituitary complex as a key step in this drug's antigonadotropic actions. Whether the active drug form is danazol itself or a metabolite is subject to further study.