Cutaneous expression of corticotropin-releasing hormone (CRH), urocortin, and CRH receptors

Studies in mammalian skin have shown expression of the genes for corticotro pin-releasing hormone (CRH) and the related urocortin peptide, with subsequ ent production of the respective peptides. Recent molecular and biochemical analyses have further revealed the presence of CRH receptors (CRHRs). Thes e CRH-Rs are functional, responding to CRH and urocortin peptides (exogenou s or produced locally) through activation of receptor(s)-mediated pathways to modify skin cell phenotype. Thus, when taken together with the previous findings of cutaneous expression of POMC and its receptors, these observati ons extend the range of regulatory elements of the hypothalamic-pituitary-a drenal axis expressed in mammalian skin. Overall, the cutaneous CRH/POMC ex pression is highly reactive to common stressors such as immune cytokines, u ltraviolet radiation, cutaneous pathology, or even the physiological change s associated with the hair cycle phase. Therefore, similar to its central a nalog, the local expression and action of CRH/POMC elements appear to be hi ghly organized and entrained, representing general mechanism of cutaneous r esponse to stressful stimuli. In such a CRH/POMC system, the CRH-Rs may be a central element.