Gut Bacteria Affects Myelin Content and Induces MS-Like Depression in Mice, Study Reports

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by Patricia Silva, PhD |

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myelin and gut bacteria

Researchers atĀ the Center of Excellence for Myelin Repair, a part of Mount Sinai, reportedĀ that gut bacteria produce compounds that were seen to affect theĀ myelinĀ content in mice and cause social avoidance behaviors. StudyĀ results indicated that targeting gut bacteria, or the gut metabolites, mightĀ help in treatingĀ neuropsychiatric disorders or complications, such as those caused by diseases likeĀ multiple sclerosis (MS).

The study, published in journalĀ eLife,Ā is titled ā€œMicrobiota-driven transcriptional changes in prefrontal cortex override genetic differences in social behavior.ā€

Previous studies from the same research team described a reduction of myelin and myelinated fibers in preclinical models of depression, postulating a biological explanation for the high rate of depression in patients with MS.

Now, the researchers identified bacteria-derived gut metabolites that can affect the content of myelin in the brains of mice and induce social avoidance behaviors, a depressive symptom.

In their experiments, the investigators transferredĀ fecal bacteria from the gut of mice with depression to mice displaying no depressive symptoms. The microbiota transfer induced social avoidance behaviors, and altered the expression of myelin-related genes and myelin content in the brains of the recipient mice.

“Our findings will help in the understanding of microbiota in modulating multiple sclerosis,” Patrizia Casaccia, MD, PhD, professor of Neuroscience, Genetics and Genomics, and Neurology, and chief of the Center of Excellence for Myelin Repair, Icahn School of Medicine at Mount Sinai, said in a recent news release. “The study provides a proof of principle that gut metabolites have the ability to affect myelin content irrespective of the genetic makeup of mice. We are hopeful these metabolites can be targeted for potential future therapies.”

To explain the mechanism of gut-brain communication, the investigators identified communities of bacteria linked with increased levels of cresol, an organic compoundĀ capable of passing the blood-brain barrier.

When the precursors of cells that form myelin were exposed to cresol, they lost their capacity to produce myelin, indicating that a gut-derived metabolite had an impact in the formation of myelin in the brain.

More studies are necessary to translate the results from this study into humans, and to identify bacterial communities with the potential to encourage the production of myelin.

MS is aĀ demyelinating diseaseĀ in which theĀ insulating covers (myelin) ofĀ nerve cells in theĀ brainĀ andĀ spinal cordĀ are damaged. This damage disrupts the ability of parts of the nervous system to communicate, resulting in a range ofĀ signsĀ andĀ symptoms, including physical,Ā mental and, in a number of patients, psychiatric problems.