Published in Cell Host & Microbe, the new research investigated how the gut microbiota affects the production of the glucagon-like peptide-1 (GLP-1) hormone by comparing germ-free and conventionally raised mice.
Led by Anita Wichmann from the University of Gothenburg, Sweden, the team reported that bacterial species in the microbiota regulate the basal levels of GLP-1 – adding that increasing the levels of GLP-1 may be an adaptive response to insufficient energy availability in the colon.
“Surprisingly, we find that the absence of microbially produced short-chain fatty acids in germ-free colon results in significantly higher plasma GLP-1 levels,” said the team. “This colonic-derived GLP-1 has an important role in slowing small intestinal transit, which may be an adaptive response for promoting nutrient absorption.”
"We are continuously discovering new functions that are regulated by the gut microbiota, which highlight its incredibly important function for health and development of diseases," commented Professor Fredrik Bäckhed, senior author of the study.
The team noted that food transit through the small intestine affects the body's absorption of nutrients and, consequently, our health.
One of the tasks of the gut microbiota, they noted, is to break down essential nutrients from our diet to provide a usable energy source in the colon.
The discovery that food transit time is regulated by the GLP-1 hormone indicates new ways to increase the intestinal absorption of nutrients, and thus potentially treat malnutrition, said the authors.
"Food transit through the small intestine is a complex balancing act, in which the gut lining must be given time to absorb nutrients but without allowing pathogenic bacteria sufficient time to colonize the small intestine,” said Wichmann. “We have discovered that food transit through the small intestine is regulated by a specific hormone called GLP-1, which is linked to our glucose metabolism and appetite.”
"We propose that colonic GLP-1 has an important function in slowing intestinal transit in response to insufficient energy availability in the colon," explained the research team.
They added that elevated GLP-1 levels and slower gastrointestinal transit times have previously been reported in patients with anorexia nervosa, "suggesting that this function may be conserved in humans."
"Our findings provide an example of how the microbial contribution to energy supply affects host gene expression and physiology in the gut."
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Source: Cell Host & Microbe
Volume 14, Issue 5, Pages 582–590, doi: 10.1016/j.chom.2013.09.012
"Microbial Modulation of Energy Availability in the Colon Regulates Intestinal Transit"
Authors: Anita Wichmann, Ava Allahyar, Thomas U. Greiner, et al