Gender differences in production and circulating levels of sex hormones and their impact on aging skin

Abstract

Serum concentrations of the sex steroids, which modulate skin structure and function, differ in aging men and women. Serum estradiol levels are unaffected by age in men, but in women, postmenopausal estrogen deficiency results in thinner, drier skin with a lower collagen content and reduced elasticity. Dehydroepiandrosterone and its sulfate form, produced by the adrenals, decline dramatically with age in both sexes, but serum concentrations are consistently lower in women. This steroid becomes the predominant source of both androgen and estrogen synthesis following menopause, and its supplementation increases skin thickness, hydration, and sebum production. Serum androgen levels decline slowly with age in men, but remain higher than in postmenopausal women. Consequently, wound healing, which is inhibited by androgens, is compromised to a greater degree in older men than women. Local synthesis of the sex steroids affects the eccrine sweat glands and hair follicles. Senile sebaceous gland hyperplasia, whereby the sebaceous gland compensates for reduced lipogenesis, is more prominent and occurs earlier in females. Dihydrotestosterone miniaturizes and reduces the number of anagen hair follicles in genetically susceptible men, leading to male-pattern baldness (androgenetic alopecia). Its impact is limited in women because their scalp hair follicles express lower levels of 5α-reductase and androgen receptor and higher levels of aromatase, which reduces the production and action of dihydrotestosterone. Thermoregulation by sweating appears to be compromised with age in both sexes. In short, circulating levels of sex hormones and the expression of key steroidogenic enzymes and receptors within the skin itself influence certain gender differences in aging skin.