Appetite control is controlled by hormones from gut signalling to brain circuits when people are hungry. Twenty minutes after a meal, microbes produce proteins that can suppress food consumption.
A new study published, in the journal Cell Metabolism, has revealed that proteins produced by mutualistsic E.coli after they have been satiated were found to influence the release of gut-brain signals, i.e. (GLP-1 and PYY).
“There are so many studies now that look at microbiota composition in different pathological conditions but they do not explore the mechanisms behind these associations,” says senior study author Sergueï Fetissov of Rouen University and INSERM’s Nutrition, Gut & Brain Laboratory in France. “Our study shows that bacterial proteins from E. coli can be involved in the same molecular pathways that are used by the body to signal satiety, and now we need to know how an altered gut microbiome can affect this physiology.”
After 20 minutes of consuming nutrients and expanding numbers, E. coli bacteria from the gut produce different kinds of proteins than they did before their feeding. Injection of small doses of the bacterial proteins produced after feeding reduced food intake in both hungry and free-fed rats and mice. Bacterial proteins, (ClpB), stimulated the release of peptide YY, a hormone associated with satiety, while “hungry” bacterial hormones did not. The opposite was true for glucagon-like peptide-1 (GLP-1), a hormone known to simulate insulin release.
The researchers determined that ClpB increased firing of neurons that reduce appetite. The role of other E.coli proteins in hunger and satiation, as well as how proteins from other species of bacteria may contribute, is still unknown.
“We now think bacteria physiologically participate in appetite regulation immediately after nutrient provision by multiplying and stimulating the release of satiety hormones from the gut,” Fetisov says. “In addition, we believe gut microbiota produce proteins that can be present in the blood longer term and modulate pathways in the brain.”
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