MONTREAL – Chronic stress triggers a biochemical ripple effect that modulates the composition of the gut microbiome, a study conducted in mice by Chinese researchers shows.
Researchers say this allows us to better understand how chronic stress increases the risk of various health problems, from irritable bowel syndrome to depression.
“The most studied mechanisms are those transmitted from the intestine and intestinal microbes to the brain,” commented Professor Vincenzo Di Marzio, a specialist in the intestinal microbiome at the Faculty of Medicine of the University of Laval. On the other hand, the mechanisms that leave the brain and reach the gut microbiota are not well known, so I think this is a very important study.
Chinese researchers discovered that mice exposed to chronic stress for two weeks had fewer cells whose role is to protect the intestines from pathogens.
More precisely, they found that a substance produced by intestinal bacteria that multiply in the presence of stress interferes with the mechanism that normally allows intestinal stem cells to transform into protective cells.
Professor Di Marzo said that the study does not explain how stress leads to the proliferation of these bacteria.
He explained, “(Researchers) have identified a new mechanism through which the brain, under stress, changes the activity of the peripheral autonomic nervous system that affects the digestive tract.” In a way that is not yet well understood, it affects the composition of the intestinal microbiota by increasing the species of bacteria that produce a metabolite that affects the proliferation of intestinal stem cells.
The researchers then found higher levels of these bacteria and the substance in question in the stool of humans suffering from depression, compared to the stool of healthy humans.
It is no secret that stress plays a leading role in the emergence of many psychosomatic diseases. Multiple studies have also shown, in recent years, that the gut microbiota has an impact that we are only just beginning to measure on multiple aspects of health.
Professor Di Marzo said the new knowledge that allows us to understand a little better the relationship between stress and the microbiome is very useful, not only because it sheds light for the first time on the relationship between the brain and the gut rather than the relationship between the brain and the gut. Alternative method.
“If there is a way for the brain to control the gut microbiota's production of certain metabolites, the brain can also direct the microbiota to have protective functions or functions that contribute to disease, through the gut of course,” he concluded.
The results of this study were published in the medical journal Cell Metabolism.
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