A new study conducted by Rouen University researchers sheds light on the possibility that gut bacteria are responsible for telling you that you're full by producing proteins that suppress food intake, according to a press release. Furthermore, the researchers injected these proteins into mice and rats and found that they acted on the brain to reduce appetite.
The researchers found that 20 minutes after the E. coli bacteria in the gut consume nutrients, they produce different types of proteins than they did prior to feeding. Additionally, this 20-minute timeframe coincided with the amount of time it takes for a person to feel full or tired after they have eaten.
In addition, injecting small doses of the bacterial proteins into both full and free-fed rats and mice reduced food intake, which led to the finding that "full" bacterial proteins release peptide YY, known to be connected with satiety, whereas the "hungry" bacterial proteins did not release this peptide.
Current appetite control models coincide with the recent findings - the common belief is that hormones from the gut send signals to circuits in your brain when you are either hungry or done eating. However, this is the first time that bacterial proteins have been found to have an effect on the release of signals that connect the gut and brain, including GLP-1 and PYY. It is also the first time that they have been shown to influence neurons in the brain connected to appetite.
"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," said Sergueï Fetissov, senior author of the study at the French university. "In addition, we believe gut microbiota produce proteins that can be present in the blood longer term and modulate pathways in the brain."