Unexpected Roles for the Second Brain: Enteric Nervous System as Master Regulator of Bowel Function.
Level 5 - mechanism / opinion, no new human data
Narrative review of physiological mechanisms without systematic search or original human data.
PubMed 30379617 · doi:10.1146/annurev-physiol-021317-121515
What was done
The authors conducted a narrative literature review examining the roles of the enteric nervous system (ENS). The review focuses on cellular diversity within the ENS (comprising over 500 million neurons and glia) and summarizes how the ENS communicates with non-neuronal gut elements, including enteroendocrine cells, the intestinal epithelium, and the mucosal immune system.
What was found
The abstract provides no quantitative findings or statistical metrics. It describes established and emerging functions of the ENS, noting that beyond canonical roles in regulating bowel motility, fluid/electrolyte epithelial secretion, and local blood flow, the ENS interacts directly with enteroendocrine cells, influences epithelial proliferation and tissue repair, modulates gut immune responses, and integrates extrinsic neural signals.
Why it matters
This review reframes the ENS from a simple motor and secretory reflex circuit into an integrative regulatory network that interfaces with gut immunity, endocrinology, and epithelial homeostasis, offering broader context for gastrointestinal health and systemic disease.
Limits
The abstract describes a narrative review rather than a systematic synthesis, precluding meta-analytic conclusions or risk-of-bias evaluation. No quantitative outcome measures, sample sizes, or specific clinical trial data are reported in the abstract.
Cited by
- supports The enteric nervous system contains a network of millions of neurons embedded within the muscular layers of the gastrointestinal tract.