In this study, 12 women and 12 men, ages 18-33 y, with androgenetic alopecia were selected for biopsies from frontal and occipital scalp sites. The androgen receptor, type I and II 5alpha-reductase, cytochrome P-450-aromatase enzyme were measured and analyzed in hair follicles from these scalp biopsies. Findings revealed that both women and men have higher levels of receptors and 5alpha-reductase type I and II in frontal hair follices than in occipital follicles, whereas higher levels of aromatase were found in their occipital follicles. There are marked quantitative differences in levels of androgen receptors and the three enzymes, which we find to be primarily in the outer root sheath of the hair follicles in the two genders. Androgen receptor content in female frontal hair follicles was approximately 40% lower than in male frontal hair follicle. Cytochrome P-450-aromatase content in women's frontal hair follicles was six times greater than in frontal hair follicles in men. Frontal hair follicles in women had 3 and 3.5 times less 5alpha-reductase type I and II, respectively, than frontal hair follicles in men. These differences in levels of androgen receptor and steroid-converting enzymes may account for the different clinical presentations of androgenetic alopecia in women and men.

Hirsutism, the presence of terminal (coarse) hairs in females in a male-like pattern, affects between 5% and 10% of women. Of the sex steroids, androgens are the most important in determining the type and distribution of hairs over the human body. Under the influence of androgens hair follicles that are producing vellus-type hairs can be stimulated to begin producing terminal hairs (i.e., terminalized). The activity of local 5alpha-reductase (5alpha-RA) determines to a great extent the production of dihydrotestosterone (DHT), and consequently the effect of androgens on hair follicles. While there are two distinct 5alpha-RA isoenzymes, type 1 and type 2, the activity of these in the facial or abdominal skin of hirsute women remains to be determined. Although the definition of idiopathic hirsutism (IH) has been an evolving process, the diagnosis of IH should be applied only to hirsute patients with normal ovulatory function and circulating androgen levels. A history of regular menses is not sufficient to exclude ovulatory dysfunction, since up to 40% of eumenorrheic hirsute women are anovulatory. The diagnosis of IH, when strictly defined, will include less than 20% of all hirsute women. The pathophysiology of IH is presumed to be a primary increase in skin 5alpha-RA activity, probably of both isoenzyme types, and possibly an alteration in androgen receptor function. Therapeutically, these patients respond to antiandrogen or 5alpha-RA inhibitor therapy. Pharmacological suppression of ovarian or adrenal androgen secretion may be of additional, albeit limited, benefit. New therapeutic strategies such as laser epilation or the use of new biological response modifiers may play an important role in offering a more effective means of treatment to remove unwanted hair. Further investigations into the genetic, molecular, and metabolic aspects of this disorder, including only well defined patients, are needed.

associated with the development of androgen-mediated skin disorders in men and women. These data suggest that CAG-repeat length in AR may affect androgen mediated gene expression in hair follicles and sebaceous glands in men and women with these androgenic skin disorders.

Human hair follicles (HF) and sebaceous glands (SG) were assessed for the presence and distribution of the cytochrome P-450-aromatase (AR) and 3B-hydroxysteroid dehydrogenase (3B-HSD) enzymes. Immunohistochemical methods were used to examine both enzymes in male and female human skin specimens at various ages and different body sites. AR was found in the external root sheath of anagen, terminal HF, and in SG, whereas the 3B-HSD was found only in the SG. AR was rarely found in telogen HF. The expression of both enzymes, AR and 3B-HSD, did not vary with body site or sex. Localizing AR in the external root sheath of anagen HF suggests that AR may have a function in the HF cycle. We hypothesize that AR may be one of many enzymes or factors that play a role in the HF cycle by regulating the level of androgens formed locally, whereas 3B-HSD is localized in SG, converting weak androgen precursors to potent androgens, stimulating lipogenesis.