Does the work of the brain depend on the intestinal microflora?
Scientists have confirmed the ancient truth of an unknown author (the following quatrain is quoted in slightly different versions and attributed to anyone, from Khayyam and the "unknown medieval doctor" to Derzhavin and Tyutchev):
Blessed is he who is early in the morning
Has a chair without compulsion.
That 's the food in the gut,
And all the pleasures are available.
Far-reaching conclusions up to "bacteria make us psychos" and the intestinal bacteria invented by one of the translators of this news will be left on the conscience of the writers. And below is the most correct statement of a controversial, but, it seems, scientific hypothesis that appeared on the Runet.
Although in fact, the authors may have confused cause and effect: in non–microbial animals, which are sometimes raised for various experiments, not only the stool is broken, but also the immune system, a variety of diseases develop, including the most severe forms of vitamin deficiency - vitamins are not synthesized in their intestines, and those that come with food are not digested... What is normal behavior here?
Microbiota influences brain development and mammalian behavior
Dmitry Safin, A computer based on ScienceNOW materials: Do Gut Bugs Practice Mind Control?
Experiments conducted by biologists from Sweden and Singapore on mice have shown that the microflora of the digestive tract affects the development of the brain and the behavior of mammals.
According to the immunologist Sven Pettersson, who took part in the study from the Karolinska Institute, twenty years ago the assumption that bacteria living on the body and in the body affect brain activity looked ridiculous. However, in the last decade, experimenters have begun to realize that the role of the microbiota has been seriously underestimated. One of the most interesting experiments in which the presence of microorganisms influenced the activity of a gene involved in the production of serotonin was performed five years ago.
The new work compared ordinary mice and rodents deprived of their microbial partners. First, the authors conducted routine testing of adults, which is used to assess activity and anxiety; it turned out that "clean" animals are more willing to explore a new space and spend less time in a dark section of the chamber, divided into illuminated and unlit sectors. Consequently, their anxiety level is reduced.
If during pregnancy the microflora of the digestive tract of an initially "clean" mouse was brought to a normal state, its offspring became less active and more anxious.
Comparison of the results shown by the usual ones (white dots and columns correspond to them)
and "clean" mice in tests for the study of open space (from above) and anxiety
(illustration from the journal Proceedings of the National Academy of Sciences).
Further studies revealed that the two groups of rodents differ in the intensity of the circulation of norepinephrine and dopamine in the striatum (subcortical part of the forebrain) and in the level of expression of dozens of genes in different parts of the brain. The presence of microorganisms also changed the expression level of two proteins (synaptophysin and PSD-95), which play an important role in the development of nerve cells, in the same striatum.
Now scientists need to find out whether the information they received corresponds to what is happening in the human body. "I didn't even think about this before, but now I understand that disorders of neuropsychiatric development can be associated with the activity of microorganisms in the digestive tract," says Brian Kolb, a neuroscientist with 35 years of experience.
The full version of the report Normal gut microbiota modulates brain development and behavior is published in PNAS.
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02.02.2011