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Type: Journal article
Title: Identification of medium/high-threshold extrinsic mechanosensitive afferent nerves to the gastrointestinal tract
Author: Song, X.
Nan Chen, B.
Zagorodnyuk, V.
Lynn, P.
Blackshaw, L.
Grundy, D.
Brunsden, A.
Costa, M.
Brookes, S.
Citation: Gastroenterology, 2009; 137(1):274-284
Publisher: W B Saunders Co
Issue Date: 2009
ISSN: 0016-5085
Statement of
Xingyun Song, Bao Nan Chen, Vladimir P. Zagorodnyuk, Penny A. Lynn, L. Ashley Blackshaw, David Grundy, Alan M. Brunsden, Marcello Costa and Simon J.H. Brookes
Abstract: BACKGROUND & AIMS: Large distentions reliably evoke sensation from the noninflamed, nonischemic bowel, but the specialized afferent axonal structures responsible have not been morphologically identified. We investigated whether their transduction sites are located on major blood vessels close to and within the gut wall. METHODS: In vitro extracellular recordings were made from mesenteric nerve trunks in guinea pig ileum, combined with rapid axonal dye filling and immunohistochemical analysis of nerve trunks. RESULTS: Recordings revealed sensory fibers with focal mechanosensitive sites in the mesenteries that could be activated by von Frey hairs and by stretch. Dye filling revealed varicose branching sensory axons on mesenteric blood vessels but no other anatomically specialized structures in mesenteric membranes or the serosa. Large-amplitude stretch and von Frey hairs also activated sensory endings within the gut wall itself but only if the submucosa was present; mechanotransduction sites in the serosa or outer muscle layers were sparse. Mechanosensitive sites in submucosa were exclusively associated with submucosal blood vessels. Submucosal endings had significantly higher thresholds to stretch than specialized low-threshold mechanoreceptors characterized previously in the rectum (P<.05) and were therefore classified as medium/high-threshold mechanoreceptors. Capsaicin (0.3–1 _mol/L) activated most mechanosensitive mesenteric (68%) and submucosal (85%) afferent endings. Similar intramural mechanosensitive afferent endings on blood vessels also exist in the colon and bladder. CONCLUSIONS: Varicose branching axons of sensory neurons on intramural blood vessels, previously shown to mediate sensory vasodilation, are transduction sites for medium/ high-threshold, stretch-sensitive mechanoreceptors, encoding large distentions in hollow viscera.
Keywords: Colon
Mesenteric Arteries
Mesenteric Veins
Neurons, Afferent
Enteric Nervous System
Guinea Pigs
Sensory Thresholds
Mechanotransduction, Cellular
Evoked Potentials
Stress, Mechanical
Time Factors
Urinary Bladder
Rights: © 2009 by the AGA Institute
DOI: 10.1053/j.gastro.2009.02.061
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Appears in Collections:Aurora harvest
Molecular and Biomedical Science publications

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