Lactic acid is an alternative source of nutrition for the brain
Food for the mindScientists have discovered an additional source of brain power
Ekaterina Lyulchak, RBC daily
A group of neurophysiologists from Germany and the Netherlands has discovered an alternative source of nutrition for the brain for the first time. After all, it was previously believed that the brain works exclusively on glucose. Using spectral analysis, scientists have found that the brain receives not only glucose from the blood coming to it, but also lactate – lactic acid, an increase in the content of which is observed when there is a discrepancy between the oxygen supply to the tissue and energy costs, that is, with active muscle work. Thus, the energy "waste" supplied by the muscles is used by the brain as an energy recharge.
A study of neurophysiologists has shown that the brain, as well as the muscles, in a situation when the body is working at the limit of its capabilities and the blood sugar level drops to a critical value, begins to eat lactate, not glucose. This discovery explained why the brain is able to work at the same level, even when other tissues and organs begin to consume several times more glucose and oxygen than usual. The brain simply switches to another mechanism for maintaining its own vital activity in conditions when working muscles are particularly in need of glucose.
Scientists obtained proof of such a theory during an experiment using the method of spectral analysis of blood taken from subjects after physical exertion. The doctors compared the chemical composition of the blood "at the entrance", which was only supposed to enter the brain and supply it with the necessary nutrients, and the blood "at the exit", which had already participated in the process of cerebral circulation. It turned out that the "spent" blood contained much less lactate than the blood only going to the brain. Further investigation showed that the brain did not store the incoming lactate, but used it as food for its cells. Thus, the brain left glucose to the muscles that needed this available fuel.
"The fact is that lactic acid is the end product of glucose metabolism in conditions of a sharp lack of oxygen. Moreover, the process of converting glucose into lactic acid can be reversed and glucose is synthesized from lactic acid," Nikolai Adrianov, Candidate of Medical Sciences, associate professor of the Department of Biochemistry of the Russian State Medical University, told RBC daily. – So, when the body works in the usual mode, glucose breaks down into two molecules of pyruvic acid; when the muscles begin to consume a lot of energy, there is not enough oxygen and the molecules of pyruvic acid break down to lactic acid molecules. The latter enter the liver, where new glucose molecules are constructed from them, which enter the blood from the liver and are used as food for the brain. And even if you increase the concentration of lactate in the blood several times, but at the same time lower the glucose level to unacceptable limits, a person will still fall into a coma. Quantitative compensation in this case will never grow into qualitative. So lactate is just a building material for glucose, not a full-fledged substitute for it."
The possibility of using several power sources for the brain at once is explained by evolution by scientists. For example, during the flight from a predator or hunting, the animal's body must accumulate all the strength and energy resources in order to ensure the work of muscles in an enhanced mode. At the same time, the animal needs the operational work of the brain, the speed of reaction and attention. Therefore, so that the muscles do not take away the brain's only source of nutrition, the body transfers neurons to a backup way of feeding.
"The body of any living being works in such a way that the absolute priority in the distribution of nutrition and energy is assigned to the brain," biophysicist, expert at the Institute of Biology of Aging Igor Artyukhov told RBC daily. –Moreover, even if the brain is able to utilize lactate along with glucose, this is explained not so much by a possible glucose deficiency caused by increased muscle work, as by a lack of oxygen, which also accompanies excessive loads."
In the human body, excess lactic acid is used as a source of carbon and energy in skeletal muscles, lungs, heart and brain. Moreover, the researchers insist that lactate serves as an excellent substrate for the brain, heart and lungs and is often utilized even before glucose, since the rate of absorption and oxidation of lactic acid is two to ten times higher than glucose. Therefore, as soon as lactic acid appears in the blood, 90% is used as a power source for the brain.
According to German and Dutch scientists, their discovery will not only be the most important stage in the study of the brain, but also the first step towards creating non-synthetic doping for the brain, which will increase its performance much better than any energy.
Portal "Eternal youth" www.vechnayamolodost.ru10.10.2008