A new gut brain circuit regulates feeding

Brain receives nutritional, mechanical, and microbial signals from the gut to regulate physiology and behavior.

Flagellin is a structural component of one of the three most ancient organelles, flagella, and a protein conserved across bacterial phyla. 

The researchers show that flagellin stimulates Toll-like receptor 5 (TLR5) on neuropod cells from the colonic lumen. This stimulation leads to PYY release onto NPY2R vagal nodose neurons to regulate feeding. Mice lacking TLR5 in neuropod cells eat more and gain more weight than controls. 

The authors also show that flagellin reduces feeding independent of immune responses, metabolic changes or the presence of gut microbiota.

The researchers thus reveal a colonic neuropod-vagus circuit that senses bacterial flagellin, highlighting microbial input as a rapid driver of feeding control and expanding paradigms of communication between the gut and the brain.

https://www.nature.com/articles/s41586-025-09301-7

https://sciencemission.com/microbial-pattern-regulates-feeding