Distribution of calcitonin gene-related peptide nerve fibers in the canine larynx.

Immunohistochemistry was used to investigate the distribution pattern of calcitonin gene-related peptide (CGRP) nerve fibers in the laryngeal mucosa, glands and intrinsic muscles of the dog. CGRP immunoreactive nerve fibers were found more frequently than substance P immunoreactive nerve fibers in every region of the larynx. In the epithelia, CGRP nerve fibers were mainly found in the epiglottis, arytenoid region and subglottis. Many taste buds were observed in the arytenoid region and were densely innervated by the CGRP nerve fibers. In the lamina propria, the plexus of CGRP nerve fibers was present, with some of these fibers associated with blood vessels. Laryngeal glands were also innervated by a few CGRP nerve fibers. In the intrinsic laryngeal muscles, abundant immunoreactivity was observed and many motor end-plate-like structures were found with CGRP immunoreactivity. These findings strongly suggest that CGRP plays an important role in all of the sensory, motor and autonomic nervous systems of the larynx.