Intestinal microbiota: in Toulouse, researchers explain how it controls our brain
The European research project THINKGUT studies the role of the intestinal microbiota in neurocognitive disorders linked to aging and obesity.
Over the past ten years, the intestinal microbiota has become a central object of study in the understanding of several diseases. “The intestinal microbiota is absolutely key in controlling the physiology of humans and animals. Composed of micro-organisms (bacteria, viruses, parasites, fungi, yeasts) which cohabit and interact with human cells, it helps digest what we eat to transform it into energy. It also gives instructions for using this transformed energy and this is essential because the body knows how to use sugar and fat, but not the energy products from bacteria”, explains Rémy Burcelin, Inserm researcher at the Institut des Maladies metabolic and cardiovascular studies of Toulouse (I2MC). And it is precisely on this discourse between our belly and our brain that the work he coordinates for the French part of the cross-border project THINKGUT financed by European funds (ERDF) focuses.
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“Bacteria rejected us for not having a memory lapse”
“The body learns from birth to defend itself, to understand what an external agent is, to digest, to absorb, to educate itself intellectually: it is the intestine-brain axis which is put in place from the first months of life. If you’re still hungry after eating, it’s because the speech is not going well, which is also one of the concerns of obesity. Similarly, bacteria appear to us not to have a memory lapse, for example not to forget where the bacteria on which they depend to survive are. One of our hypotheses is to say that, as we age, memory lapses and impaired cognitive functions could come from a modification of the intestinal microbiota”, continues Rémy Burcelin.
For two years, the I2MC team worked with those of Pr José Manuel Fernández-Real of the Biomedical Research Institute of Girona (Spain) and Dr Anne Abot of the company Enterosys of Labège to study, in 1700 patients, the correlation between the composition of their gut microbiota and cognitive questionnaires. After complex statistical studies, the Toulouse researchers were able to link a group of bacteria associated with cognitive disorders and a group of bacteria associated with high cognitive functions.
“The next step was to transfer the bacteria in question into focused mice (raised in a sterile environment) to program their gut and see if they gain cognitive functions. We will then study the evolution of cognitive functions in mice that have aged,” explains Rémy Burcelin, who works with Bruno Guiard’s team at the Animal Cognition Research Center (CRCA/CBI/Toulouse III Paul-Sabatier University /CNRS). Another hypothesis is put forward: intestinal information is lost over time under the effect of a degraded microbial balance. And not all individuals would be affected by this degradation. “We think that, when we have bacteria capable of talking to the brain, they can tell the aging brain not to forget what they taught it in its youth,” says Rémy Burcelin.
It is therefore impossible not to wonder whether, in humans, certain bacteria can have a therapeutic action. Several years of additional research will be needed to transform bacteria into drugs or probiotics and perhaps hope to re-educate our brain through our intestinal microbiota.
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