Calcitonin gene-related peptide in human nasal mucosa

To explore the potential range of functions for calcitonin gene-related peptide (CGRP) in human mucosa, we quantified human inferior turbinate nasal mucosal CGRP content by radioimmunoassay, localized CGRP-immunoreactivity by immunohistochemistry, detected 125I-CGRP binding sites by autoradiography, and tested the ability of CGRP to induce submucosal gland secretion in short-term explant culture of human nasal mucosa. Nasal mucosa contained 0.45-0.54 pmol CGRP/g wet wt (n = 18). Immunoreactive CGRP was found in nerve fibers that densely innervated the walls of small muscular arteries arterioles. Venules and venous sinusoids were innervated by individual CGRP staining fibers. Occasional CGRP-containing nerve fibers were also noted adjacent to submucosal gland acini, near the epithelial basement membrane, and between epithelial cells. Specific 125I-CGRP binding sites were concentrated on small muscular arteries and arterioles. CGRP (4 microM) did not stimulate glycoconjugate or lactoferrin release from mucosal explants. These results indicate that in the human nasal mucosa, CGRP is present in nerve fibers, which most likely represent nociceptive sensorimotor nerves that innervate vascular structures (muscular arteries, arterioles, veins and venous sinusoids). It is likely that CGRP release from sensory neurons may play a role in the regulation of vasomotor responses, but no evidence for a role of CGRP in glandular secretion was found.