To investigate the varying response of the pilosebaceous unit to androgens functional studies were performed on the effects of testosterone and 5α-dihydrotestosterone on cultured human sebocytes derived from different skin regions. In addition, the effect of spironolactone on the proliferation of androgen-stimulated human sebocytes derived from facial skin was evaluated. Testosterone (1O-11 to 10-5M), 5α-dihydrotestosterone (10-11 to 10-5M) and spironolactone (10-12 to 10-7M) were added for 10 days as single substances or in combinations to human sebocytes in secondary culture maintained in a serum-free medium. Cell proliferation was assessed using a fluorometric assay. Intracellular lipids were extracted from sebocytes treated with androgens (10-7M) for 10 days after con-fluency. Testosterone inhibited the proliferation of sebocytes derived from the legs with a 50%-inhibitory concentration at 10-5M and induced a 50% decrease of intracellular lipids. In contrast, 5 α-dihydro testosterone stimulated the activity of leg sebocytes with a 50% increase of proliferation at 10-5M, and a 175% increase of intracellular lipids. On the other hand, the proliferation of facial sebocytes was significantly stimulated by testosterone with a 50%-stimulatory concentration at 10-6 to 10-5Mand mostly by 5α-dihydrotestosterone with a 50% enhancement at 10-8 to 10-7M. Spironolactone inhibited the proliferation of facial sebocytes in a dose-dependent manner with a 25%-inhibitory concentration at 10-9M. Simultaneous treatment of facial sebocytes with spironolactone and testosterone or 5α-dihydrotestosterone resulted in decreased proliferation when compared to the growth obtained under androgens alone. Moreover, spironolactone at 10-7M neutralized the stimulatory activity of 5α-dihydrotestos-terone at all concentrations tested. In contrast to previous reports of no androgen effect on human dermal papilla cells in culture, our results show a specialized response of human sebocytes to androgens dependent on the localization of the sebaceous glands. The direct inhibition of sebocyte proliferation by spironolactone and its antagonistic activity to androgens at the cellular level are indicative of a receptor-monitored e