title: The microbiome is essential for normal gut intrinsic primary afferent neuron excitability in the mouse.
abstract: BACKGROUND
  The role of intestinal microbiota in the development and function of host physiology is of high interest, especially with respect to the nervous system. While strong evidence has accrued that intestinal bacteria alter host nervous system function, mechanisms by which this occurs have remained elusive. For this reason, we have carried out experiments examining the electrophysiological properties of neurons in the myenteric plexus of the enteric nervous system (ENS) in germ-free (GF) mice compared with specific pathogen-free (SPF) control mice and adult germ-free mice that have been conventionalized (CONV-GF) with intestinal bacteria.
  
  
  METHODS
  Segments of jejunum from 8 to 12 week old GF, SPF, and CONV-GF mice were dissected to expose the myenteric plexus. Intracellular recordings in current-clamp mode were made by impaling cells with sharp microelectrodes. Action potential (AP) shapes, firing thresholds, the number of APs fired at 2× threshold, and passive membrane characteristics were measured.
  
  
  RESULTS
  In GF mice, excitability was decreased in myenteric afterhyperpolarization (AH) neurons as measured by a lower resting membrane potential and by the number of APs generated at 2× threshold. The post AP slow afterhyperpolarization (sAHP) was prolonged for GF compared with SPF and CONV-GF animals. Passive membrane characteristics were also altered in GF mice by a decrease in input resistance.
  
  
  CONCLUSIONS
  Here, we report the novel finding that commensal intestinal microbiota are necessary for normal excitability of gut sensory neurons and thus provide a potential mechanism for the transfer of information between the microbiota and nervous system.
authors.affiliation: McMaster Brain-Body Institute at St Joseph's Healthcare, Hamilton ON, Canada. neufelk@mcmaster.ca
authors.forename: K A
authors.initials: KA
authors.lastname: McVey Neufeld
authors.forename: Y K
authors.initials: YK
authors.lastname: Mao
authors.forename: J
authors.initials: J
authors.lastname: Bienenstock
authors.forename: J A
authors.initials: JA
authors.lastname: Foster
authors.forename: W A
authors.initials: WA
authors.lastname: Kunze
mesh_terms: D000818:Animals; D005260:Female; D005856:Germ-Free Life / Q000502:physiology; D007583:Jejunum / Q000382:microbiology*; D008297:Male; D008564:Membrane Potentials / Q000502:physiology; D054892:Metagenome; D051379:Mice; D009197:Myenteric Plexus / Q000502:physiology*; D009475:Neurons, Afferent / Q000502:physiology*; D018408:Patch-Clamp Techniques