Identification of a rhythmic firing pattern in the enteric nervous system that generates rhythmic electrical activity in smooth muscle

Nick J. Spencer, Timothy J. Hibberd, Lee Travis, Lukasz Wiklendt, Marcello Costa, Hongzhen Hu, Simon J. Brookes, David A. Wattchow, Phil G. Dinning, Damien J. Keating, Julian Sorensen

Research output: Contribution to journalArticle

22 Scopus citations

Abstract

The enteric nervous system (ENS) contains millions of neurons essential for organization of motor behavior of the intestine. It is well established that the large intestine requires ENS activity to drive propulsive motor behaviors. However, the firing pattern of the ENS underlying propagating neurogenic contractions of the large intestine remains unknown. To identify this, we used high-resolution neuronal imaging with electrophysiology from neighboring smooth muscle. Myoelectric activity underlying propagating neurogenic contractions along murine large intestine [also referred to as colonic migrating motor complexes, (CMMCs)] consisted of prolonged bursts of rhythmic depolarizations at a frequency of ~2 Hz. Temporal coordination of this activity in the smooth muscle over large spatial fields (~7 mm, longitudinally) was dependent on the ENS. During quiescent periods between neurogenic contractions, recordings from large populations of enteric neurons, in mice of either sex, revealed ongoing activity. The onset of neurogenic contractions was characterized by the emergence of temporally synchronized activity across large populations of excitatory and inhibitory neurons. This neuronal firing pattern was rhythmic and temporally synchronized across large numbers of ganglia at ~2 Hz. ENS activation preceded smooth muscle depolarization, indicating rhythmic depolarizations in smooth muscle were controlled by firing of enteric neurons. The cyclical emergence of temporally coordinated firing of large populations of enteric neurons represents a unique neural motor pattern outside the CNS. This is the first direct observation of rhythmic firing in the ENS underlying rhythmic electrical depolarizations in smooth muscle. The pattern of neuronal activity we identified underlies the generation of CMMCs.

Original languageEnglish
Pages (from-to)5507-5522
Number of pages16
JournalJournal of Neuroscience
Volume38
Issue number24
DOIs
StatePublished - Jun 13 2018

Keywords

  • Colon
  • Colonic migrating motor complex
  • Enteric nervous system
  • Gastrointestinal tract
  • Myenteric plexus
  • Pacemaker cell

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    Spencer, N. J., Hibberd, T. J., Travis, L., Wiklendt, L., Costa, M., Hu, H., Brookes, S. J., Wattchow, D. A., Dinning, P. G., Keating, D. J., & Sorensen, J. (2018). Identification of a rhythmic firing pattern in the enteric nervous system that generates rhythmic electrical activity in smooth muscle. Journal of Neuroscience, 38(24), 5507-5522. https://doi.org/10.1523/JNEUROSCI.3489-17.2018