2023-06-13 22:16:09
“A healthy mind…with a healthy microbiota”. This might be summarized a recent study demonstrating the close link between the composition of the intestinal microbiota and depressive disorders. In the same work, the scientists also provided evidence that direct communication between the gut microbiota and the brain requires the presence of the vagus nerve, paving the way for therapeutic solutions.
The human body, in adulthood, is made up of 100,000 billion cells. It is also in close collaboration with a substantially equivalent number of microbes – bacteria, viruses or fungi. This microbial community, called microbiota, plays a key role in many essential biological processes such as immunity or metabolism.
In recent years, scientists have been looking more specifically at the intestinal microbiota and its composition. Its in-depth study may allow us to better understand its implications for human health. Recently, for example, a link has been established between the intestinal microbiota and certain inflammatory reactions. Previously, a direct dialogue between the intestinal microbiota and the brain, associated with metabolic disorders such as diabetes or obesity, had also been demonstrated.
In a joint study between the Institut Pasteur, CNRS and Inserm, scientists have revealed, in an animal model, another strong link between the brain and the intestinal microbiota. The researchers observed that the transfer of microbiota from stressed mice to healthy mice caused all the symptoms characteristic of a depressive state in the latter: reduced motivation, loss of pleasure and apathy.
The vagus nerve allows direct communication between the gut microbiota and the brain
The scientists did not stop at this observation and pushed their study further, sketching out a possible therapeutic avenue. They also carried out a vagotomy on the mice that had just received microbiota from stressed mice, that is to say a surgical section of the vagus nerve in the abdomen. Result ? These mice with newly unbalanced gut microbiota do not show symptoms of depressive disorder. “We have shown that the decoupling of the intestine and the brain by vagotomy is sufficient to protect the subject from a depressive state produced by intestinal dysbiosis” explains Pierre-Marie Lledo, CNRS research director and head of the Perception unit and dissertation at the Institut Pasteur.
By revealing the protective role of vagotomy in the induction of certain forms of depression, this study conducted in animals makes it possible to consider alternative therapeutic strategies to relieve depression of 30% of people treated with antidepressants who do not feel any beneficial effect despite this treatment. It now remains to test this hypothesis and validate the results of this work in humans.
This study falls within the framework of the priority scientific axis Brain connectivity diseases and neurodegenerative diseases of the 2019-2023 strategic plan of the Institut Pasteur.
This work received financial support from AG2R La Mondiale.
Source:
Gut microbiota changes require vagus nerve integrity to promote depressive-like behaviors in mice, Molecular Psychiatry, 2 mai 2023
Eleni Siopi1,2Mathieu Galerne2,4Manon Rivagorda2,4Soham Saha1Carine Moigneu1Stephanie Moriceau3Mathilde Bigot1Franck Oury2,5 and Pierre-Marie Lledo1,5
1Institut Pasteur, University of Paris Cité, CNRS UMR 3571, Perception and Memory Unit, 75015 Paris, France.
2Paris Cité University, CNRS, INSERM, Necker Institute for Sick Children-
INEM, 75015 Paris, France.
3Platform for Neurobehavior and Metabolism, Structure Fédérative de Recherche Necker, 26 INSERM US24/CNRS UAR 3633, 75015 Paris, France.
4These authors contributed equally: Mathieu Galerne, Manon Rivagorda.
5These authors jointly supervised this work: Franck Oury, Pierre-Marie Lledo.
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