In some ways it is really obvious how exercise may work against depression. If you are to exercise in nature, of course then the healing powers of the natural world will work wonders on your psyche. Even if you exercise in a gym, though, then the sense of taking control of your life is a mental balm and that is without considering the physiological benefits of being fit, having a heart that is effectively pumping blood to your brain and carrying oxygen and nutrition with it. All of this is true but now researchers have discovered a new mechanism working at the cellular level which may explain further some of the power of exercise to combat depression.
The new research was based on the fact we already know that exercise increases levels of a protein called PGC-1a1 in skeletal muscle. These researchers wanted to see what, if any, role this protein may have in the effects of exercise.
To test this they exposed mice to mild stress in the form of a loud noises and flashing lights. After five weeks of this mice with normal levels of PGC-1a1 showed some symptoms of depression while mice with high levels of PGC1a1 displayed no depressive behaviour.
When the researchers investigated further they found that mice with high levels of PGC-1a1 also had high levels of KAT enzymes. What these KAT enzymes do is convert a substance produced during stress called kynurenine into kynuric acid.
The researchers found that mice given kynurenine showed depressive behaviour but not if they had high PGC-1a1 levels. This is because the KAT enzymes in the muscles of the mice with high PGC-1a1 were converting the kynurenine into kynuric acid. People with mental illnesses are also known to have high levels of kynurenine.
By no means does this answer everything about how depression works but it does suggest that future treatments for depression might include building skeletal muscle rather than targeting the brain directly. In the meantime, of course, you could do a lot worse for your physical and mental wellbeing than go for a walk in the park.
