Skin, androgens

Sebum is released by the sebaceous glands and naturally maintains hair and skin hydration. An increase in androgen levels, especially during puberty, can cause an increase in the size of the sebaceous gland and the production of abnormally high levels of sebum within those glands. This excess sebum can result in plugged follicles and acne formation. 

Pharmacology Dutasteride inhibits the conversion of testosterone to 5 -dihydrotestosterone (DHT), the androgen primarily responsible for the initial development and subsequent enlargement of the prostate gland. Testosterone is converted to DHT by the enzyme 5 -reductase, which exists as 2 isoforms, type 1 and type 2. The type 2 isoenzyme is primarily active in the reproductive tissues while the type 1 isoenzyme is also responsible for testosterone conversion in the skin and liver. 

Topical minoxidil is effective in reversing the progressive miniaturization of scalp hairs associated with androgenic alopecia (male pattern baldness). It is a hereditary disorder due to excessive conversion of testosterone to dehydrocorticosterone in the scalp skin in genetically susceptible men. 

Like other steroids, testosterone acts intracellularly in target cells. In skin, prostate, seminal vesicles, and epididymis, it is converted to 5k -dihydrotestosterone by 5K-reductase. In these tissues, dihydrotestosterone is the dominant androgen. The distribution of this enzyme in the fetus is different and has important developmental implications. 

Inhibition of the function of the sebaceous glands in the skin is caused by glucocorticoids whilst androgens stimulate their function (170). 

Zouboulis CC, Degitz K. Androgen action on human skin—from basic research to clinical significance. Exp Dermatol 2004 13(Suppl 4) 5-10. 

Oily skin causes acne, and higher androgenic AAS caused elevated secretion from sebaceous glands. This is because these gland receptor-sites have a higher affinity to DHT. Most AAS convert to DHT to some degree while others are DHT derivatives. 

ACTH stimulates the adrenal cortex to produce glucocorticoids, mineralocorticoids, and androgens. ACTH increases the activity of cholesterol esterase, the enzyme that catalyzes the rate-limiting step of steroid hormone production cholesterol - pregnenolone. ACTH also stimulates adrenal hypertrophy and hyperplasia. When given chronically in pharmacologic doses, corticotropin causes increased skin pigmentation. 

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