Hormones and Hormone Precursors of the Skin

Abstract The skin forms a barrier between the outside environment and the inner organs. Besides its physical barrier function, it also plays a role in regulating responses to the outside environment by engaging in the systemic regulation of hormones. In certain conditions, it transduces external stimuli through local production of hormones that can act either locally to protect from further harmful stimuli (e.g., by increasing pigmentation) or systemically (e.g., by producing endogenous opioids or vitamin D). In this chapter, we aim to cover the most important hormonal regulators of the skin, focusing on vitamin D and the skin equivalent of the hypothalamic–pituitary–adrenal axis, the role of the skin in regulating steroidogenesis, and the role of hormones in skin pathophysiology.