Human male sexual functions do not require aromatization of testosterone: a study using tamoxifen, testolactone, and dihydrotestosterone.

This study was designed to examine whether testosterone needs to be converted to estradiol in order to exert fully its effects on sexuality in the human male. Administration of the estrogen receptor antagonist tamoxifen and the aromatase inhibitor testolactone were without effect on parameters of sexual functions. Replacement of testosterone substitution therapy of agonadal men by dihydrotestosterone was likewise not associated with any change of sexual functioning. Administration of dihydrotestosterone to eugonadal men led to a transient increase of nocturnal sexual dreams and erections and irritability, waning after 3-4 weeks of dihydrotestosterone administration. It is concluded that aromatization of testosterone is not required and that dihydrotestosterone maintains sexual functions in the adult male with an established sex life.