title: Two immunohistochemically identified populations of calcitonin gene-related peptide (CGRP)-immunoreactive axons in human skin.
abstract: Double labelling immunofluorescence has shown two populations of unmyelinated sensory axons in human skin that contain immunoreactivity (IR) to calcitonin gene-related peptide (CGRP). One population also contains IR to substance P (SP), whilst the other also contains IR to somatostatin (SOM). Axons containing both CGRP-IR and SOM-IR comprised more than 75% of CGRP-IR axons associated with the epidermis; the rest of the CGRP-IR axons contained SP-IR. No axons contained both SP-IR and SOM-IR. Some dermal blood vessels were surrounded by axons containing both CGRP-IR and SP-IR, but most CGRP-IR perivascular axons contained SOM-IR without SP-IR. Sweat glands were well supplied with sensory axons containing CGRP-IR and weak SOM-IR but not SP-IR. Therefore, CGRP is a histochemical marker for a larger number of unmyelinated cutaneous afferents in human skin than is SP. CGRP itself may have a role in the mediation of responses to stimulation of at least two populations of sensory axons.
mesh_terms: D001369:Axons / Q000032:analysis; D001808:Blood Vessels / Q000294:innervation; D015740:Calcitonin Gene-Related Peptide; D005455:Fluorescent Antibody Technique; D006801:Humans; D009475:Neurons, Afferent / Q000032:analysis* / Q000145:classification; D009479:Neuropeptides / Q000032:analysis*; D012867:Skin / Q000294:innervation*; D013004:Somatostatin / Q000032:analysis; D013373:Substance P / Q000032:analysis
chemical_list: D009479:Neuropeptides; D013373:Substance P; D013004:Somatostatin; D015740:Calcitonin Gene-Related Peptide