Wednesday, 30 December 2015

Gut bacteria signal to the brain when someone is "full"

Lots of food
Big meal and full-up
Twenty minutes after a meal, gut microbes produce proteins that can suppress food intake in animals. New research has shown how these proteins, when injected into mice and rats, act on the brain, reducing appetite, suggesting that gut bacteria may help people control when and how much they eat.

The new evidence coexists with current models of appetite control, which involve hormones from the gut signalling to brain circuits when we're hungry or done eating. The bacterial proteins--produced by mutualistic E. coli after they've been satiated--were found for the first time to influence the release of gut-brain signals (e.g., GLP-1 and PYY) as well as activate appetite-regulated neurons in the brain.

Mealtime brings an influx of nutrients to the bacteria in your gut. In response, they divide and replace any members lost in the development of stool. The study raises an interesting theory: since gut microbes depend on us for a place to live, it is to their advantage for populations to remain stable. It would make sense, then, if they had a way to communicate to the host when they're not full, promoting host to ingest nutrients again.

For details on the study, see:

Jonathan Breton, Naouel Tennoune, Nicolas Lucas, Marie Francois, Romain Legrand, Justine Jacquemot, Alexis Goichon, Charlène Guérin, Johann Peltier, Martine Pestel-Caron, Philippe Chan, David Vaudry, Jean-Claude do Rego, Fabienne Liénard, Luc Pénicaud, Xavier Fioramonti, Ivor S. Ebenezer, Tomas Hökfelt, Pierre Déchelotte, Sergueï O. Fetissov.Gut Commensal E. coli Proteins Activate Host Satiety Pathways following Nutrient-Induced Bacterial Growth. Cell Metabolism, 2015; DOI: 10.1016/j.cmet.2015.10.017

 Posted by Dr. Tim Sandle