Feeding for the brain
Selenium "restores" brains by activating neurogenesis
Today we know that nerve cells are regenerating. Neurogenesis – the process of formation of new neurons – is promoted by physical activity, but only now scientists have figured out the mechanism of their action. As it turned out, selenium plays an important role in it – a trace element vital for the functioning of the human body, which is contained in a number of available foods.
The absolute record holder for the content of selenium is the Brazil nut (it is enough to eat only a couple of pieces a day). There is a lot of selenium in wild mushrooms, seafood (from lobsters and mussels to squid, fish and seaweed), as well as in poultry fillets, garlic, buckwheat, etc. The source can also be the so–called "selenium" yeast, primarily beer yeast, which is obtained by cultivation in a selenium-rich environment - they contain this important trace element in the most easily digestible form.
The phrase "nerve cells do not recover" has practically become a catch phrase. However, not so long ago it became clear that new neurons can be formed even in an adult. Neurogenesis takes place in the hippocampus, a part of the limbic system of the brain responsible for learning and memory processes. By old age, this process slows down – this is what age-related cognitive decline is associated with.
When the effect of enhancing neurogenesis under the influence of physical exertion was discovered, scientists began to find out which compounds released into the blood during muscle activity could be responsible for it.
Earlier, an international research team experimentally established that such a molecular factor could be selenoprotein P (SEPP1) – an extracellular protein that includes the remains of an amino acid containing the trace element selenium. It turned out that in the blood of actively moving laboratory mice, the level of SEPP1 was more than twice as high as in the control. Later, scientists confirmed their findings in experiments on mice with the sepp1 gene encoding this protein "turned off": in such genetically engineered individuals, running did not stimulate the formation of neurons.
Now scientists have investigated the effect on neurogenesis of selenium itself. After all, this trace element is known to be important for maintaining normal brain function, and its deficiency is associated with the development of age-related neurodegenerative pathologies such as Alzheimer's and Parkinson's disease.
In cell cultures of hippocampal neurons of two–month-old mice treated with selenium, the researchers found an increase in the number and size of neurospheres - clusters of neuronal stem cells, which serves as an indicator of an increase in the intensity of neurogenesis.
At the next stage, laboratory mice were the object of experiments, which were injected with selenium compounds directly into the hippocampus for a week. The result is the growth of proliferating (multiplying) precursors of neurons in the dentate gyrus of the hippocampus. As it turned out later, this effect is realized in the body due to the activation of resting stem cells.
Subsequently, the effect of selenium on neurogenesis was tested in two more series of experiments. In the first of them, selenium was added to the food of "elderly" 17-month-old mice for a month, after which their cognitive abilities were tested using behavioral tests. And it turned out that the experimental mice were tested much better than the control ones. It is obvious that selenium supplementation reversed the age-related decline in cognitive functions, which is characteristic not only for humans, but also for rodents.
The object of another series of experiments were mice with a model ischemic "stroke" in the hippocampus caused by a vasoconstrictor drug. After such brain damage, the results of behavioral testing of control animals became noticeably worse. But those mice that received selenium before or immediately after the "stroke" recovered their memory and learning abilities fairly quickly.
Article by Leiter et al. Selenium mediates exercise-induced adult neurogenesis and reverses learning disabilities induced by hippocampal injury and aging is published in the journal Cell Metabolism.
The results of this great work open up new possibilities for influencing mental abilities. The average person who eats a balanced diet usually gets enough selenium. At the same time, selenium is found in many foods, and its amount in the diet can be easily increased in case of a deficiency of this element.
By the way, in addition to the positive effect on the "brains", selenium is necessary for the normal functioning of the immune and endocrine systems, it is widely used for the prevention of cancer, etc. But it is also not worth getting carried away, first of all, with dietary supplements with selenium. This trace element is necessary for a person in relatively small quantities – no more than 300 micrograms per day, in reality, the physiological need for it is 3-4 times less. Taking unreasonably high doses can cause poisoning with a number of serious consequences, including the development of type 2 diabetes mellitus.
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