The skin as an endocrine organ

Abstract

Through the definition of novel biological activities of hormones and their diversity on different skin cell types, it has become apparent that the skin itself possesses the capacity to generate several hormones and substances with hormone-like activity. These substances appear to act through paracrine, autocrine, intracrine and endocrine mechanisms to fulfill their pleiotropic effects. Also new is the knowledge that the skin can metabolize hormones and produce derivatives with potentially systemic activity. These findings point towards novel concepts in our understanding of the role of skin and of its hormones as important players in homeostasis and disorders of the entire human organism. Finally, the scientists active in the field of dermato-endocrinology expect that their activities will exploit the pharmacological and therapeutic function of hormone mediators, their receptors and antagonists. The latter idea has already been realized for corticosteroids, androgens, estrogens, topical vitamin D analogues and retinoids which have today an established place in clinical dermatology.

Keywords: dermatology; endocrinology; hormone; human; skin; skin physiology.

Figure 1

Modes of hormone action. Classical and modern endocrine functions: Hormones produced by established endocrine organs or other distant sources, respectively, reach target tissues through the circulation. Paracrine function: Hormones act locally on cells other than those that produce them. Juxtacrine function: Hormones produced in one cell interact directly with a receptor of an immediate neighboring cell. Autocrine function: Hormones act on the cell in which they are produced. Intracrine function: Hormones get activated in the cell in which they are produced and act on it by binding to nuclear receptors.

Figure 2

Skin diseases and manifestations associated with diabetes mellitus. (a) skin atrophy, (b) candida-induced intertrigo, (c) scleromyxedema Arndt-Gottron, (d) bullosis diabeticorum, (e) necrobiosis lipoidica, (f) acanthosis nigiricans, (g) granuloma anulare disseminatum, (h) bullous hemorrhagic erysipelas (i) peripheral vascular necrosis (gangraine).