Substance P- and CGRP-immunoreactive fibers in the chicken carotid bodies after nodose ganglionectomy and midcervical vagotomy.

The chicken carotid body is richly innervated by branches from the vagus nerve immunostained with the monoclonal antibody TuJ1 to neuron-specific class III beta-tubulin. Furthermore, peptidergic nerve fibers are densely distributed in and around the carotid body. After transection of the vagus nerve proximal to the nodose ganglion, TuJ1-immunoreactive fibers did not change in density but substance P- and CGRP-immunoreactive fibers were conspicuously decreased in and around the carotid body. After removal of the nodose ganglion, TuJ1-immunoreactive fibers markedly diminished and substance P- and CGRP-immunoreactive fibers almost disappeared. These results indicate that the vast majority of substance P- and CGRP-immunoreactive fibers in the chicken carotid body originate from the vagal ganglia.