From Epithelial Sensing to Visceral Pain: Neuropod and Enterochromaffin Cells in Gut Neuroepithelial Circuits

Visceral pain is a central feature of chronic gastrointestinal disorders, yet the epithelial sensory mechanisms that shape afferent input before it enters pain-relevant neural pathways remain insufficiently integrated into current models. This review advances the concept that the intestinal epithelium is not only a barrier or endocrine interface, but also an active neuroepithelial regulatory layer positioned upstream of visceral sensory signaling. Neuropod-cell studies established that specialized epithelial cells can communicate rapidly with vagal neurons and preserve luminal stimulus identity through transmitter-selective coding. Enterochromaffin cells extend this framework as polymodal epithelial sensory transducers that detect chemical, microbial, neurohumoral, and mechanical cues, convert them into serotonergic afferent signaling, and can causally amplify visceral hypersensitivity in experimental models. Complementing these amplifying pathways, GUCY2C^high (guanylate cyclase C-enriched) neuropod-like epithelial cells reveal a pain-restraining mechanism that regulates dorsal root ganglion excitability and preserves linaclotide-responsive suppression of nociceptive output in preclinical systems. Together, these findings support an integrative model in which epithelial sensory circuits may act as filters of biological meaning, amplifiers of afferent gain, and brakes on aberrant nociceptive escalation. This framework does not replace neural, immune, or central mechanisms of visceral pain, but adds an upstream epithelial tier that may shape pain vulnerability, persistence, or treatment responsiveness in selected contexts. Defining the cellular logic, molecular mediators, and human relevance of these circuits will be essential for advancing neuroepithelial pain biology toward disease-relevant and therapeutic applications.