Scientists also say that exercise is a cushion against depression. Working out makes people, and animals feel better.
Even so, nobody really knows why.
Researchers cannot ask mice how they feel. However, they know the behavior of mice in reaction to stress. Mice lose weight. They do not crave sugar, and they are listless. In an experiment, mice were subject to low-level stress over five weeks. They became depressed.
Scientists knew the mice would feel better if they exercised. They wanted to know how it was happening. A certain enzyme (PGC-1alphai1) increases in the brain after exercise.
They bred mice with a high level of the enzyme. The mice started producing more of the enzyme even without exercising. After being exposed to stress, they became only mildly depressed.
Scientists tracked a substance called kynurenine. More of it is found in the bloodstream after stress. It causes inflammation within the brain. This substance seems to lead to depression.
However, the enzyme PGC-1alphai1 attacked and broke up the kynurenine. The kynurenine could not get into the brain. Therefore, the stress did not turn into depression.
An exercise program produced a big increase in PGC-1alphai1 in humans. One scientist said, “you reduce the risk of getting depression when you exercise.”
More research on whether PGC-1alphai1 can cure depression is ahead.
Source: The New York Times October 1, 2014