INNERVATION OF LARYNGEAL NERVE PARAGANGLIA - AN ANTEROGRADE TRACING AND IMMUNOHISTOCHEMICAL STUDY IN THE RAT

Carotid body-like organs, paraganglia, frequently occur in the superio r and recurrent laryngeal nerves. The paraganglia are supplied with a rich innervation of unknown origin. In the present study, the origin o f the innervation of the paraganglia of the rat was studied with two d ifferent techniques. One approach was anterograde tracing of wheat-ger m agglutinin-horseradish peroxidase after injection into the nodose an d jugular ganglia of the vagus and the superior cervical ganglion. The other approach was immunohistochemical staining for neuropeptides aft er excision of the superior cervical ganglion, or vagotomy. Antisera a gainst neuropeptide Y, vasoactive intestinal polypeptide, and calciton in gene-related peptide were utilized. Both the tracing method and cal citonin gene-related peptide immunohistochemistry after vagotomy showe d that the paraganglia receive sensory innervation from the vagal gang lia. No labeling was detected in the paraganglia after injection of wh eat-germ agglutinin-horseradish peroxidase in the superior cervical ga nglion. Excision of this ganglion did not lead to a decrease in the ne uropeptide-Y innervation in the paraganglia, but most of this innervat ion in the surrounding blood vessels disappeared. The observations sho w that the superior cervical ganglion does not contribute to the inner vation in the paraganglia and that the neuropeptide-Y innervation of t he blood vessels originates from the superior cervical ganglion wherea s that of the paraganglia has another origin, most likely local gangli onic cells. The results also suggest that the vasoactive intestinal po lypeptide innervation in the paraganglia arises from local ganglionic cells. The two approaches complemented each other in mapping the affer ent and efferent nerve supply of the paraganglia. (C) 1994 Wiley-Liss, Inc.