2023-06-23 14:56:36
In a recently published French study In Molecular Psychiatry, researchers from the Institut Pasteur, CNRS and Inserm have unveiled a link between the composition of the intestinal microbiota and depressive behaviour. This work, conducted on mice, has yet to be validated in humans, but might offer innovative therapeutic avenues if the results were confirmed…
Assuming that chronic stress is a risk factor for depression that can also disrupt various aspects of homeostasis, including the gut microbiota, the researchers transferred microbiota from chronically stressed mice to healthy mice. They observed that this resulted in the latter typical symptoms of depression similar to those observed in stressed mice: decreased motivation, loss of pleasure and apathy. They also found that this transfer induced lasting changes in serotonin and dopamine neurotransmission pathways in the brainstem and hippocampus; these changes were associated with deficits in hippocampal neurogenesis and induced neuroinflammatory responses – observations that support the link between microbiota and the brain.
Then wanting to study the role that the vagus nerve plays in this link, the researchers carried out a vagotomy (surgical section of the vagus nerve in the abdomen) in healthy mice before transferring the microbiota of stressed mice to them. Results : recipient mice no longer had depressive symptoms nor the other neurological changes seen in the first part of the experiment. “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”, explain Pierre-Marie Lledo, last author of the study.
These results suggest that acting on the microbiota-vagus nerve-brain pathway might constitute a therapeutic alternative for depression resistant to currently available treatments. Indeed, studies are already underway on the stimulation of the vagus nerve in these indications. To be continued…
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