Neural control of skin water content: The sebaceous gland, a neglected target.

Normally supple and moist, the skin is the largest organ and outermost structure of the body. It is composed of separate but interconnected layers, working as a whole but controlled distinctively by numerous modulatory signals arising from several areas of the central, peripheral and autonomous nervous systems (CNS, PNS, ANS, respectively). Almost all functions mediated by that organ depend significantly upon water content levels of its constitutive layers. There is increasing evidence suggesting that a pivotal mechanism involved in water content modulation is the sebaceous gland. Its dysfunction has also been associated with debilitating dry skin problems such as xerosis, atopic dermatitis, psoriasis and rosacea. Generally, sebum secretion levels are considered to be dependent upon sex hormone (e.g. testosterone, DHEA) release – attributed to neuroendocrine actions (hypothalamus-pituitary-gonadal axis-control) on various organs. However, clear evidence indicate that specific neuropeptides and peripheral nerves can also participate significantly to the regulation of sebum secretion and, hence, to skin moisture and functions. This editorial aims at summarizing some of the main findings in neural control mechanisms of normal skin functions – specifically those associated with sebaceous gland activity.