THE REGIONAL DISTRIBUTION OF NEUROPEPTIDES IN HUMAN SKIN AS ASSESSED BY RADIOIMMUNOASSAY AND HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

In this study radioimmunoassay was used to determine neuropeptide leve ls in extracts from 17 differing anatomical regions of human skin. Mar ked regional variations of neuropeptide content for human skin were fo und and these variations are likely to reflect true physiological func tions for the neuropeptides studied. In general the tachykinins, subst ance P (SP), neurokinin A (NKA) and calcitonin gene-related peptide (C GRP) were found in highest concentrations in regions of skin with the greatest tactile sensation. By contrast, highest concentrations of vas oactive intestinal peptide (VIP) and peptide histidine methionine (PHM ) were found in axillary skin, where they probably play a part in axil lary eccrine sweat production. Neurotensin was not found in any of the skin areas sampled, suggesting that it is relatively unimportant in h uman physiological skin control. Reverse-phase high-performance liquid chromatography (rpHPLC) was used to verify the results of radioimmuno assay. Both SP and NKA occurred in several regions in both their reduc ed and oxidized forms, as well as displaying molecular heterogeneity. CGRP occurred as one molecular species, this being alpha-cCGRP, sugges ting that this is the predominant molecular form in human skin. Likewi se, both VIP and PHM displayed molecular homogeneity in the regions in vestigated by rpHPLC.