Distribution of androgen metabolizing enzymes in isolated tissues of human forehead and axillary skin.

The distribution of androgen metabolism in human skin was studied using tissues isolated either by direct dissection of axillary skin or by dissection of collagenase-digested forehead and axillary skin. All tissues (epidermis, sweat glands, sebaceous glands, hair follicles and dermis) were found to contain 17beta-, 3beta- and 3alpha-hydroxysteroid dehydrogenase (HSD) activities, 3beta-hydroxysteroid dehydrogenase-delta4--5 isomerase (delta5-3beta-HSD) activity and 5alpha-reductase activity. All tissues converted testosterone into 5alpha-dihydrotestosterone. In confirmation of previous histochemical studies, over 90% of the delta5-3beta-HSD of forehead skin was found in the sebaceous glands. In forehead skin, 40--66% of the 5alpha-reductase activity was in the sebaceous glands, while in axillary skin 50--70% was in the sweat glands, especially the apocrine glands. There was a more even distribution of 17beta-HSD activity in skin tissues than histochemical studies have indicated previously. Knowledge of the distribution of these enzymes has helped in the understanding of the function of androgen metabolism in skin.