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Front. Neurosci. | doi: 10.3389/fnins.2018.00112

Development of an ex vivo method for multi-unit recording of microbiota-colonic-neural signalling in real time.

  • 1Physiology, University College Cork, Ireland
  • 2APC Microbiome Institute, University College Cork, Ireland

Background & Objectives: Bidirectional signalling between the gastrointestinal tract and the brain is vital for maintaining whole-body homeostasis. Moreover, emerging evidence implicates vagal afferent signalling in the modulation of host physiology by microbes, which are most abundant in the colon. This study aims to optimise and advance dissection and recording techniques to facilitate real-time recordings of afferent neural signals originating in the distal colon.
New Protocol: This paper describes a dissection technique, which facilitates extracellular electrophysiological recordings from visceral pelvic, spinal and vagal afferent neurons in response to stimulation of the distal colon.
Examples of application: Focal application of 75mM KCl to a section of distal colon with exposed submucosal or myenteric nerve cell bodies and sensory nerve endings evoked activity in the superior mesenteric plexus and the vagal nerve. Noradrenaline stimulated nerve activity in the superior mesenteric plexus, whereas application of carbachol stimulated vagal nerve activity. Exposure of an ex vivo section of distal colon with an intact colonic mucosa to peptidoglycan, but not lipopolysaccharide, evoked vagal nerve firing.
Discussion: Previous studies have recorded vagal signalling evoked by bacteria in the small intestine. The technical advances of this dissection and recording technique facilitates recording of afferent nerve signals evoked in extrinsic sensory pathways by neuromodulatory reagents applied to the distal colon. Moreover, we have demonstrated vagal afferent activation evoked by bacterial products applied to the distal colonic mucosa. This protocol may contribute to our understanding of functional bowel disorders where gut-brain communication is dysfunctional, and facilitate real-time interrogation of microbiota-gut-brain signalling.

Keywords: vagus, Microbiota-gut-brain axis, extracellular electrophysiology, Microdissection, distal colon.

Received: 08 Dec 2017; Accepted: 13 Feb 2018.

Edited by:

Stuart M. Brierley, Flinders University, Australia

Reviewed by:

Simon J H. Brookes, Flinders University, Australia
Kirsteen Browning, Pennsylvania State University, United States  

Copyright: © 2018 O'Malley and Buckley. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Dervla O'Malley, University College Cork, Physiology, Western Gateway Building, Western Road, Cork, T12 XF62, Ireland, d.omalley@ucc.ie