Does exercise protect against depression?

Physical exercise has many beneficial effects on human health, including protection against stress-induced depression.

However, until now the mechanisms that govern this protective effect were unknown.

In a new study on mice, Swedish scientists concluded that exercise causes changes in skeletal muscle that can clear the blood of a substance that builds up during stress and is harmful to the brain. The research was published in the journal Cell.

Scientists, however, report that neurobiologically, depression is still understood and the study is only one piece of the puzzle in that it explains the protective biochemical changes due to of physical exercises and protect the brain from damage in stressful situations.

The PGC-1A1 protein is known to increase in skeletal muscle with exercise and its production is conditioned by exercise.

In this study, the researchers used genetically modified mice with high levels of PGC-1A1 in skeletal muscle, which showed many of the characteristics of well-trained muscle, even without exercise.

These and normal control mice were exposed to stressful environments such as loud noise, flashing lights, and circadian rhythm changes at irregular time intervals.

After 5 weeks of mild stress, normal mice developed depressive behavior, while GMO mice, with characteristics of well-trained muscles, had no symptoms of depression.

The lead author of the study reports the initial research hypothesis of the team of scientists, namely that exercise stimulates the production of a substance with a beneficial effect on the brain.

And they discovered that well-trained muscles produce an enzyme that cleanses the body of harmful substances. So in this context the function of the muscles resembles that of the kidneys and the liver.

The scientists found that mice with higher levels of PGC-1A1 in their muscles also had higher levels of enzymes called CAT. They convert the substance that is formed during stress /kynurenine/ into kynurenic acid, which cannot pass from the blood to the brain.

The exact function of kynurenine is not known, but high levels of the substance are found in patients with mental illness.

The researchers who conducted the study stated that when normal mice were given kynurenine, they demonstrated depressive-like behavior, while GMO mice with increased levels of PGC-1A1 in their muscles were not affected.

In fact, these animals never show elevated levels of kynurenine in the blood, because the CAT enzymes in their well-trained muscles quickly combine it and convert it into kynurenic acid, which is the pure manifestation of this protective against stress mechanism.

The scientists who conducted the study are hopeful, it opens up possibilities for the creation of a new pharmacological principle for the treatment of depression.

In this regard, attempts can be made to influence skeletal muscle function or possibly new drugs to be developed or therapies to target directly to the brain.

Based on the research conducted, it can be concluded that skeletal muscles have a detoxifying effect which when activated can protect the brain from strokes and related mental disorders.

Depression is among the most common mental disorders in the world. The World Health Organization reports that over 350 million people are affected.