Run, mouse, run
Bacteria from the intestines of marathon runners made mice more resilient
It turns lactic acid into a substance that makes the heart work better
Polina Loseva, "The Attic"
In pursuit of useful inhabitants of the human intestine, American and Canadian researchers have reached athletes-runners. Collecting samples of their excrement before and after the Boston Marathon, scientists found that athletes have more Veillonella bacteria than people who lead a sedentary lifestyle. Researchers have suggested that it's lactic acid, which is formed in working muscles and "flows" from the blood into the intestines. Veillonella bacteria turn it into a short-chain fatty acid, which increases the endurance of the body.
The set of symbiotic microbes in the human body can change under the influence of a variety of factors: age, food preferences, health status and even because of close relatives. In particular, scientists have previously discovered that the microflora of athletes differs from the microflora of people who are not engaged in professional sports. But it is still unknown whether any representatives of the intramural community influence sports success.
Researchers from America and Canada studied the intestinal contents of 15 participants of the 2015 Boston Marathon a few days before and after the competition. In parallel, they conducted similar tests on a control group – 10 participants of the experiment who did not play sports. It turned out that in comparison with "unsportsmanlike" people, the intestines of runners contain more Veillonella bacteria, and after the marathon they become even more.
To test whether these bacteria are directly related to exercise, the researchers replicated the experiment on mice. They isolated a bacterium of the genus Veillonella from the excrement of one of the marathon runners and planted it in the intestines of mice. Next, the scientists tested experimental mice and their companions from the control group on a treadmill. Animals with Veillonella bacteria proved to be hardier, lasting 13% longer.
Scientists have confirmed their assumptions that Veillonella is associated with sports on an independent group of athletes: ultramarathoners and Olympic rowers. They also had a lot of these bacteria. Then the researchers sequenced the genomes of all microbes from the intestines of this independent group and tracked the relative number of which genes grew after training. This may indicate not only the reproduction of certain bacteria, but also their physiological role.
It turned out that physical exercise increases the number of genes associated with the breakdown of lactic acid – a byproduct of glucose metabolism in muscles, which is actively formed under heavy loads. But what about bacteria Veillonella are known for converting lactates into propionate salts of propionic acid, which are known for their stimulating effect on glucose breakdown, heart contractions and oxygen absorption from the air.
To make sure that the bacteria get some amount of lactic acid from the muscles, scientists injected lactic acid labeled with a heavy carbon isotope into the blood of mice. After a while, they found it already in the intestine and concluded that the intestinal wall "leaks", allowing intestinal microbes to receive lactates. However, the presence of bacteria in itself does not seem to affect the amount of lactic acid in the blood: in mice injected with bacteria of the genus Veillonella, the concentration of lactates remained the same as in the control group, to which other microbes were introduced. Based on these data, the researchers suggested that the role of bacteria is not so much to purify the blood from lactic acid, as in the production of propionates. And when the experimental mice were injected with propionate into the intestines without planting any bacteria, they again showed good results on the treadmill, lasting longer than the control group.
The authors of the work note that the relationship of runners with bacteria Veillonella is another good example of symbiosis. During exercise, the amount of lactate in the blood increases, it enters the intestine and creates a comfortable environment for microbes that break it down. The cleavage product turns out to be propionate, which enhances the endurance of an athlete and allows his body to run longer, and his muscles to produce even more favorite food for intestinal bacteria.
Article by Scheiman et al. Meta-omics analysis of elite athletes identifies a performance-enhancing microbe that functions via lactate metabolism published in the journal Nature Medicine.
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