Distribution of vagal CGRP-immunoreactive fibers in the lower esophagus and the cardia of the stomach of the rat.
We have examined whether the smooth muscle fibers in the lower esophagus and the cardia of the stomach of the rat are innervated by calcitonin gene-related peptide-immunoreactive (CGRP-ir) fibers coming from the nucleus ambiguus. Immunohistochemical observations revealed that there were many CGRP-ir fibers and free endings in all external muscular layers of the lower esophagus and the cardia. Occasionally, bundles of CGRP-ir fibers were found in the inner oblique muscle layer of the cardia. There were also many CGRP-ir fibers in the mucous membrane in the lower esophagus and the cardia. When Fluorogold was injected into the junction of the lower esophagus and the cardia, many retrogradely labeled neurons were found in the compact formation of the nucleus ambiguus and the dorsal motor nucleus of the vagus nerve. Double labeling with immunohistochemistry for CGRP and the retrograde tracer Fluorogold showed that almost all of neurons (more than 90%) in the nucleus ambiguus that project to the lower esophagus or the cardia contained CGRP, while no CGRP-ir neurons were found in the dorsal motor nucleus of the vagus nerve. These results indicate that the vagal motor neurons of the nucleus ambiguus that contain CGRP project not only to the striated muscle fibers of the esophagus but also to the smooth muscle fibers of the external muscle layers of the lower esophagus and the cardia.
Hayakawa
Tetsu
T
Department of Anatomy, Hyogo College of Medicine, Mukogawa, Nishinomiya, Hyogo 663-8501, Japan. tetsu@hyo-med.ac.jp
Kuwahara
Sachi
S
Maeda
Seishi
S
Tanaka
Koichi
K
Seki
Makoto
M
D000818:Animals; D001369:Axons / Q000378:metabolism* / Q000648:ultrastructure; D001931:Brain Mapping; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism*; D004063:Digestion / Q000502:physiology; D004947:Esophagus / Q000166:cytology / Q000294:innervation*; D005456:Fluorescent Dyes; D005769:Gastrointestinal Motility / Q000502:physiology; D007150:Immunohistochemistry; D008297:Male; D008526:Medulla Oblongata / Q000166:cytology / Q000378:metabolism; D018482:Muscle, Skeletal / Q000166:cytology / Q000294:innervation; D009130:Muscle, Smooth / Q000166:cytology / Q000294:innervation*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013266:Stilbamidines; D013270:Stomach / Q000166:cytology / Q000294:innervation*; D014630:Vagus Nerve / Q000166:cytology / Q000378:metabolism*
C049774:2-hydroxy-4,4'-diamidinostilbene, methanesulfonate salt; D005456:Fluorescent Dyes; D013266:Stilbamidines; D015740:Calcitonin Gene-Related Peptide