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

Abstract

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 × 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<0.01), and their response to GnRH stimulus (p<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<0.01). The decrease in body temperature was significantly greater (p<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.