Colon Cells Detect Bacterial Flagellin and Send the Brain a 'Stop Eating' Signal: Mouse Study
A circuit in mice was identified in which sensory cells in the colon detect flagellin from gut bacteria and reduce food intake through the vagus nerve.
The gut is also a sensory organ that detects nutrients and sends signals to the brain. Researchers at the Laboratory of Gut Brain Neurobiology at Duke University in the United States reported in Nature, from mouse experiments, that the gut detects not only nutrients but also molecules from gut microbes in real time and uses them to regulate behaviour. It is a new pathway of the gut-brain axis.
Flagellin → neuropod cells → vagus nerve
The researchers focused on flagellin, a structural protein of the motility apparatus that many bacteria share. In the mouse colon, flagellin stimulated Toll-like receptor 5 (TLR5) on neuropod cells, the sensory cells of the gut epithelium that release peptide YY (PYY). These cells then released PYY, which was passed to vagal nodose ganglion neurons carrying the NPY2R receptor, and food intake decreased as a result.
Mice lacking TLR5 in these cells ate more than control mice and gained more weight. Flagellin did not stimulate the nerves directly, and it reduced food intake regardless of immune responses, metabolic changes or the presence of gut microbes. The researchers named this sensation the 'neurobiotic sense.'
Limitations
This is basic research confirmed in mice, and it has not been shown whether the same circuit works the same way in the human gut. Whether it can be applied to appetite or weight control will require separate studies.
- TLR5 on mouse colon neuropod cells detects the bacterial flagellar protein flagellin
- Food intake falls through PYY release and the NPY2R vagal neuron pathway
- Mice lacking TLR5 ate more and gained weight; a 'neurobiotic sense' independent of immunity and the presence of microbes
Limitations This is basic research in mice. Whether the circuit works in people, and whether it can be applied to obesity or appetite control, has not been confirmed.
Original research
- Liu WW, et al. · Duke University. A gut sense for a microbial pattern regulates feeding. Nature. DOI: 10.1038/s41586-025-09301-7
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