Neuropeptides and hypothalamic-pituitary-adrenal axis in the pathogenesis of alopecia areata

Abstract

Alopecia areata(AA)is an autoimmune disorder of hair follicles.It has been shown that AA is closely associated with psychological stress.There are two hotspots in the current research on psychological stress in AA,namely neuropeptides and hypothalamic-pituitary-adrenal(HPA)axis.As the brain-skin connection with local neuroimmunoendocrine circuitry.immunomodulatory neuropeptides include substance P,calcitonin gene-related peptide (CGRP)and nffrve growth factor (NGF).ete;these neuropeptieds make up of abrain-hair follicle axis(BHA)together with stress effeetor cells,such as mast cells,macrophages and γδ T cells.Hair follicles are highly sensitive to these neuropeptides,and it seems that stress influences hair growth through the called brain.hair follicle axis.It has been evidenced that skin has established a fully functional peripheral equivalent Of HPA axis as an independent,local stress response system.Skin and its appendages can produce the same mediators as involved in systemic stress response.For example,corticotropin-releasing hormone(CRH)can be secreted by human skin. Key words: Alopecia areata; Neuropeptides; Brain-hair follicle axis