Enteric nervous system: sensory transduction, neural circuits and gastrointestinal motility

The gastrointestinal tract is the only internal organ to have evolved with its own independent nervous system, known as the enteric nervous system (ENS). This Review provides an update on advances that have been made in our understanding of how neurons within the ENS coordinate sensory and motor functions. Understanding this function is critical for determining how deficits in neurogenic motor patterns arise. Knowledge of how distension or chemical stimulation of the bowel evokes sensory responses in the ENS and central nervous system have progressed, including critical elements that underlie the mechanotransduction of distension-evoked colonic peristalsis. Contrary to original thought, evidence suggests that mucosal serotonin is not required for peristalsis or colonic migrating motor complexes, although it can modulate their characteristics. Chemosensory stimuli applied to the lumen can release substances from enteroendocrine cells, which could subsequently modulate ENS activity. Advances have been made in optogenetic technologies, such that specific neurochemical classes of enteric neurons can be stimulated. A major focus of this Review will be the latest advances in our understanding of how intrinsic sensory neurons in the ENS detect and respond to sensory stimuli and how these mechanisms differ from extrinsic sensory nerve endings in the gut that underlie the gut–brain axis.

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Acknowledgements

H.H. was supported by grants from the NIH, R01GM101218, R01DK103901 and R01AA027065, Washington University School of Medicine Digestive Disease Research Core Center (NIDDK P30 DK052574), The Center for the Study of Itch of the Department of Anaesthesiology at Washington University School of Medicine. N.J.S. is supported by NH&MRC of Australia, grants APP1156427 and APP1156416.

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Authors and Affiliations

  1. College of Medicine and Public Health & Centre for Neuroscience, Flinders University, Adelaide, Australia Nick J. Spencer
  2. Department of Anesthesiology, The Center for the Study of Itch, Washington University School of Medicine, St Louis, MO, USA Hongzhen Hu
  1. Nick J. Spencer