Hormones and the Pilosebaceous Unit

The document from 2009 discusses the role of hormones in the functioning of the pilosebaceous unit, which is part of the skin that includes hair follicles and sebaceous glands. It highlights that the skin acts as an endocrine organ by synthesizing hormones and housing various hormone receptors. Over the past decade, it was found that steroid hormones, phospholipid hormones, retinoids, nuclear receptor ligands, and stress hormones are crucial in regulating the development of pilosebaceous units, sebaceous gland lipogenesis, and hair cycling. Androgens, in particular, have been extensively studied due to their clinical significance in skin disorders like acne, androgenetic alopecia, and seborrhea. These conditions often occur despite normal circulating androgen levels, due to overexpression of androgenic enzymes and heightened sensitivity of androgen receptors in the skin, a phenomenon referred to as "cutaneous hyperandrogenism." The regulation of skin steroidogenesis is similar to that in gonads and adrenals. The document suggests that more research is needed to understand the regional differences in androgen-mediated skin disorders and proposes the pilosebaceous unit as an ideal model for dermatological endocrinology studies.