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Researchers from the Karolinska Institutet in Sweden get to grips with the molecular basis of the saying “sound mind, sound body.” The key appears to be how muscles reduce levels of stress markers in the blood.
A new study explains how muscle activity benefits the whole body.
Studies have shown that exercising not only promotes burning fat but also benefits the mind.
Even before science understood why, carrying out physical activity was already considered useful in reducing depressive symptoms for some people.
In 2014, for the first time, a group of researchers from the Karolinska Institutet described exactly how exercise might benefit the brain.
The Swedish team showed that when muscles were put to work during exercise, they produced an enzyme that broke down kynurenine – a compound that is present at higher levels in people with depression and other mental disorders.
The enzyme produced by muscle converts kynurenine into kynurenic acid, which cannot cross the blood-brain barrier. In this way, the brain is protected from certain stress-induced changes that are thought to occur in depression.
Effectively, the muscles clear the blood of this compound, preventing its negative consequences in the brain.
Examining kynurenine in more detail
This week, the same team of scientists mentioned above release their findings from the latest study to probe this mechanism; the results are published in the journal Cell Metabolism.
In their latest study, they delve deeper into this relationship and examine how kynurenine benefits more than just the brain; its impact is wide-ranging. The project was lead by Jorge Ruas, from the Department of Physiology and Pharmacology at the Karolinska Institutet.
They demonstrate that the previously outlined relationship goes both ways, explaining that the same reduction in kynurenine that helps reduce depression also boosts fat metabolism and the anti-inflammatory response.
10 minutes of exercise enough to boost brain
Just 10 minutes of activity can give the brain a brief upgrade, improving performance in mental tasks.
For the study, the team fed rats a high-fat diet that increased their blood sugar levels and made them overweight. Then, they gave the mice a daily injection of kynurenic acid, the breakdown product of kynurenine. The mice treated with kynurenic acid continued to be fed the high-fat diet.
Despite no change in caloric intake, the mice stopped putting on weight and their glucose tolerance — a marker for metabolic disorders — improved.