delta 5-3 beta-hydroxysteroid dehydrogenase activity in sebaceous glands of scalp in male-pattern baldness.

Sebaceous glands were isolated by manual dissection using a stereomicroscope from skin specimens of bald scalp of men with male-pattern baldness undergoing hair transplant or scalp reduction surgery and also from specimens taken from hairy and bald areas of scalp at autopsy of adult male victims of accidental death within 3 h post mortem. Homogenates of the isolated glands exhibited activities of delta 5-3 beta-hydroxysteroid dehydrogenase (3 beta HSD), 17 beta-hydroxysteroid dehydrogenase, and testosterone 5 alpha-reductase by the conversion of [3H]dehydroepiandrosterone (DHA) to 3H-delta 4-androstenedione (AD), [3H]testosterone, and [3H]dihydrotestosterone. Homogenates of glands from bald (B) scalp had greater 3 beta HSD activity than homogenates of glands from hairy (H) scalp. After differential centrifugation, 3 beta HSD activity was found mainly in the microsomal and 105,000 X g supernatant fractions. Specific activity of the enzyme based on protein mass was highest in the microsomal fraction; however, the total 3 beta HSD activity in the 105,000 X g supernatent of B glands was significantly (p less than .01) greater than that of H glands. 3 beta HSD activity in sebaceous glands isolated from autopsy specimens did not differ from that of glands isolated from surgical specimens in apparent Km (0.13-0.14 microM), pH optima (8.0), or coenzyme requirement for NAD. Since substantial 3 beta HSD activity was present in the cytosol, and cytosol of B glands showed increased 3 beta HSD activity, the increased conversion of DHA to AD may be a critical step for androgenic action and may be responsible for excessive androgenicity in male-pattern baldness.