Motor innervation by enteric nerve fibers containing both nitric oxide synthase and galanin immunoreactivities in the striated muscle of the rat esophagus

The relationship between nitric oxide synthase (NOS)- and galanin-immunorea ctive nerve terminals and the origin of NOS-immunoreactive nerve terminals on the motor endplates in the striated muscles of the rat esophagus was inv estigated. Double immunohistochemical staining revealed a dual innervation of motor endplates by calcitonin gene-related peptide (CGRP)-immunoreactive axons and by axons that were immunoreactive for both NOS and galanin. On a verage, 91% of NOS terminals were galanin immunoreactive. NOS-immunoreactiv e fibers were revealed at 67% of endplates, identified by the presence of C GRP terminals. The left vagus and superior laryngeal nerve were cut and 15 days allowed for terminals to degenerate. This caused a significant loss of CGRP fibers, but did not affect the density of innervation of the striated muscle by NOS-immunoreactive fibers. Thus the NOS/galanin fibers are deduc ed to originate from ganglia in the esophageal wall. This is supported by o ur observation of numerous NOS-immunoreactive nerve cell bodies in the myen teric ganglia of the esophagus, 74% of which were galanin immunoreactive. T here were no CGRP-immunoreactive nerve cell bodies in the wall of the esoph agus.