Inhibition of gonadotropin-releasing hormone receptors in rat anterior pituitary monolayer cell cultures by danazol

Thermoregulatory and endocrine effects of a low dose of danazol in postmenopausal women: interaction with the effect of naloxone

Before and on the 30th day of danazol administration (200 mg/day), in six postmenopausal women the activity of endogenous opioid peptides has been indirectly evaluated by the effect on LH secretion and body temperature (measured as rectal temperature) exerted by the infusion of the opioid antagonist naloxone (1.6 mg/h x 4 h preceded by 1.6 mg iv bolus). Before and during danazol administration a GnRH test (100 mcg iv bolus) was also performed to evaluate possible variations in pituitary responsiveness to GnRH. Danazol significantly reduced mean plasma levels of LH and FSH (p less than 0.01), and their response to GnRH stimulus (p less than 0.05). Either before or during danazol administration mean plasma LH and FSH levels did not vary during the infusion of naloxone, while body temperature significantly decreased (p less than 0.01). The decrease in body temperature was significantly greater (p less than 0.05) during danazol than before treatment. The present data suggest that in postmenopausal women a low dose of danazol exerts an antigonadotropic effect mainly reducing the pituitary responsiveness to GnRH. The enhanced hypothermic response to naloxone observed during danazol administration also seems to suggest that in postmenopausal women a low dose of danazol enhances the thermoregulatory role of endogenous opioid peptides.

Danazol stimulates the release of follicle-stimulating hormone and inhibits the release of prolactin in vitro studies on rat pituitary cell cultures

The actions of danazol on the release of gonadotropins and prolactin (PRL) were investigated by using a culture of rat anterior pituitary gland cells. The addition of danazol in the range between 10(-9) M and 10(-5) M elevated the levels of follicle-stimulating hormone (FSH) in a dose-dependent manner. Danazol at 10(-5) M caused a 70% increase in FSH levels over the control. The intracellular contents of FSH was also increased by danazol, suggesting its stimulatory effect on both the synthesis and release of FSH. Danazol had no effect on the release of luteinizing hormone (LH). Danazol diminished the sensitivity of gonadotrophs to luteinizing hormone-releasing hormone (LHRH) in that the LHRH-induced release of both FSH and LH was suppressed. The amount of PRL released into medium was decreased by danazol in a dose-dependent way.