Bacteria living in the human intestine, can influence mood and even cause depression. How they exercise “remote control” brain, was previously unclear. Researchers from the University College Cork in Ireland seem to have solved the mystery.
The scientists compared normal mice whose gastrointestinal tracts are teeming with bacteria, with “sterile” rodents, whose microbiome was destroyed with a powerful dose of the antibiotic. The researchers found that mice without the microbes in the areas of the brain involved in the regulation of anxiety (the amygdala and prefrontal cortex), had a surplus of some types of molecules — microRNAs — and lack of other. Mouse without germs less likely to suffer depression than populated microbiome.
Researchers still don’t know how intestinal bacteria affect microRNAs. Perhaps the microbes send signals along the vagus nerve — a sort of information highway that runs from the gut to the brain. There is also a version that in this information support the role played by the metabolic products of microbes that affect the blood and it transports chemical molecules of the brain. Research is ongoing.
Commented head of the laboratory of viruses and microorganisms of Institute of Microbiology of RAS Andrey LETAROV: — There is the concept that the microbiome affects everything from disease to psychological properties of a personality. In this work, we can see that the molecules siRNA mice lacking bacteria differ from molecules to mice with a normal microbiome. With this attribute the differences in behavior of mice. But it is not very clear that what is affected: either the bacteria influence gene expression in the brain, or plays the role of some indirect chain that is associated with the metabolism. But in any case, allocate a microbe that can cause depression, as of yet.