Neuropeptides and skin aging.

Abstract Neuropeptides (NP) are peptides that are released as chemical messengers from nerve cells. They act either in an endocrine manner, where they reach their target cells via the bloodstream or a paracrine manner, as co-transmitters modulating the function of neurotransmitters. To date approximately 100 different NP have been described in the literature. In recent years, several studies have documented that human skin expresses several functional receptors for NP, such as corticotropin-releasing hormone, melanocortins, β-endorphin, vasoactive intestinal polypeptide, neuropeptide Y and calcitonin gene-related peptide. These receptors modulate the production of inflammatory cytokines, proliferation, differentiation, lipogenesis and hormone metabolism in human skin cells. In addition, several NP are directly produced by human skin cells, indicating the complexity of understanding the real functions of NPs in human skin. In this review we address the possible effects of neuropeptides on the pathogenesis of aged skin.