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Morphological demonstration of a vagal inhibitory pathway to the lower esophageal sphincter via nitrergic neurons in the rat esophagus
Author(s) -
Kuramoto H.,
Kadowaki M.,
Yoshida N.
Publication year - 2013
Publication title -
neurogastroenterology and motility
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.489
H-Index - 105
eISSN - 1365-2982
pISSN - 1350-1925
DOI - 10.1111/nmo.12146
Subject(s) - vasoactive intestinal peptide , esophagus , vagus nerve , stimulation , inhibitory postsynaptic potential , colocalization , choline acetyltransferase , myenteric plexus , endocrinology , medicine , enteric nervous system , biology , immunohistochemistry , anatomy , neuroscience , cholinergic , neuropeptide , receptor
Background The involvement of vagal parasympathetic efferents in esophageal myenteric neurons in vagal inhibitory pathways to the lower esophageal sphincter ( LES ) is not clear. Thus, this study was performed to demonstrate morphologically the presence of vagal inhibitory pathways to the LES via esophageal neurons. Methods Fast Blue ( FB ) was injected into the LES of Wistar rats, and 3 days after injection, the animals were subjected to electrical stimulation of the vagus nerve. The esophagus was processed for immunohistochemistry for Fos that was an immediate‐early gene as a marker of neuronal activity, nitric oxide synthase ( NOS ), vasoactive intestinal polypeptide ( VIP ) and choline acetyltransferase (Ch AT ). The immunoreactivities were then compared with the FB labeling in esophageal neurons. Key Results Fast Blue‐labeled neurons were observed within an esophageal area of 30 mm oral to the LES , with the highest frequency in the esophagus just above the LES . Most of the FB ‐labeled neurons were positive for NOS and VIP , but a few for Ch AT . Following vagal‐electrical stimulation, one fourth of the FB ‐labeled neurons presented nuclei expressing Fos and most of these Fos/ FB neurons were NOS ‐positive. Conclusions & Inferences A majority of the FB ‐labeled esophageal neurons appeared to be descending motor neurons innervating the LES . Moreover, the colocalization of VIP and NOS in most of the LES ‐projecting neurons suggests that VIP and NO released from these neurons induce LES relaxation, and the innervation of the vagal efferents to the LES ‐projecting esophageal neurons in the distal esophagus implies a vagal inhibitory pathway responsible for LES relaxation.