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Secretin activates vagal primary afferent neurons in the rat: evidence from electrophysiological and immunohistochemical studies

Secretin activates vagal primary afferent neurons in the rat: evidence from electrophysiological... In this study, we evaluated the vagal afferent response to secretin at physiological concentrations and localized the site of secretin's action on vagal afferent pathways in the rat. The discharge of sensory neurons supplying the gastrointestinal tract was recorded from nodose ganglia. Of 91 neurons activated by electrical vagal stimulation, 19 neurons showed an increase in firing rate in response to intestinal perfusion of 5-HT (from 1.5 ± 0.2 to 25 ± 4 impulses/20 s) but no response to intestinal distension. A close intra-arterial injection of secretin (2.5 and 5.0 pmol) elicited responses in 15 of these 19 neurons (from 1.5 ± 0.2 impulses/20 s at basal to 21 ± 4 and 43 ± 5 impulses/20 s, respectively). Subdiaphragmatic vagotomy and perivagal application of capsaicin, but not supranodose vagotomy, completely abolished the secretin-elicited vagal nodose neuronal response. In a separate study, 9 tension receptor afferents among 91 neurons responded positively to intestinal distension but failed to respond to luminal 5-HT. These nine neurons also showed no response to administration of secretin. As expected, immunohistochemical studies showed that secretin administration significantly increased the number of Fos-positive neurons in vagal nodose ganglia. In conclusion, we demonstrated for the first time that vagal sensory neurons are activated by secretin at physiological concentrations. A subpopulation of secretin-sensitive vagal afferent fibers is located in the intestinal mucosa, many of which are responsive to luminal 5-HT. vagal afferent; nodose ganglia; intestinal mucosa; vagotomy Address for reprint requests and other correspondence: C. Owyang, 3912 Taubman Center, Box 0362, Univ. of Michigan Health System, Ann Arbor, MI 48109 (e-mail: cowyang@umich.edu ) http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png AJP - Gastrointestinal and Liver Physiology The American Physiological Society

Secretin activates vagal primary afferent neurons in the rat: evidence from electrophysiological and immunohistochemical studies

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References (29)

Publisher
The American Physiological Society
Copyright
Copyright © 2011 the American Physiological Society
ISSN
0193-1857
eISSN
1522-1547
DOI
10.1152/ajpgi.00039.2005
pmid
15920018
Publisher site
See Article on Publisher Site

Abstract

In this study, we evaluated the vagal afferent response to secretin at physiological concentrations and localized the site of secretin's action on vagal afferent pathways in the rat. The discharge of sensory neurons supplying the gastrointestinal tract was recorded from nodose ganglia. Of 91 neurons activated by electrical vagal stimulation, 19 neurons showed an increase in firing rate in response to intestinal perfusion of 5-HT (from 1.5 ± 0.2 to 25 ± 4 impulses/20 s) but no response to intestinal distension. A close intra-arterial injection of secretin (2.5 and 5.0 pmol) elicited responses in 15 of these 19 neurons (from 1.5 ± 0.2 impulses/20 s at basal to 21 ± 4 and 43 ± 5 impulses/20 s, respectively). Subdiaphragmatic vagotomy and perivagal application of capsaicin, but not supranodose vagotomy, completely abolished the secretin-elicited vagal nodose neuronal response. In a separate study, 9 tension receptor afferents among 91 neurons responded positively to intestinal distension but failed to respond to luminal 5-HT. These nine neurons also showed no response to administration of secretin. As expected, immunohistochemical studies showed that secretin administration significantly increased the number of Fos-positive neurons in vagal nodose ganglia. In conclusion, we demonstrated for the first time that vagal sensory neurons are activated by secretin at physiological concentrations. A subpopulation of secretin-sensitive vagal afferent fibers is located in the intestinal mucosa, many of which are responsive to luminal 5-HT. vagal afferent; nodose ganglia; intestinal mucosa; vagotomy Address for reprint requests and other correspondence: C. Owyang, 3912 Taubman Center, Box 0362, Univ. of Michigan Health System, Ann Arbor, MI 48109 (e-mail: cowyang@umich.edu )

Journal

AJP - Gastrointestinal and Liver Physiology – The American Physiological Society

Published: Oct 1, 2005

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