Stop worrying about your children! | Salon Life
http://www.salon.com/mwt/feature/2009/05/04/free_range_kids/index.html

A reasonably sensible look at the risks affecting children in modern life.

Researchers at Princeton University recently made a remarkable discovery about the brains of rats that exercise. Some of their neurons respond differently to stress than the neurons of slothful rats...

rats that had exercised, even if they had received the oxidizing chemical, were relatively nonchalant under stress. When placed in the unfamiliar space, they didn’t run for dark corners and hide, like the unexercised rats. They insouciantly explored. The “cells born from running,” the researchers concluded, appeared to have been “specifically buffered from exposure to a stressful experience.” The rats had created, through running, a brain that seemed biochemically, molecularly, calm.

Other researchers have looked at how exercise alters the activity of dopamine, another neurotransmitter in the brain, while still others have concentrated on the antioxidant powers of moderate exercise. Anxiety in rodents and people has been linked with excessive oxidative stress, which can lead to cell death, including in the brain. Moderate exercise, though, appears to dampen the effects of oxidative stress. In an experiment led by researchers at the University of Houston and reported at the Society for Neuroscience meeting, rats whose oxidative-stress levels had been artificially increased with injections of certain chemicals were extremely anxious when faced with unfamiliar terrain during laboratory testing. But rats that had exercised, even if they had received the oxidizing chemical, were relatively nonchalant under stress. When placed in the unfamiliar space, they didn’t run for dark corners and hide, like the unexercised rats. They insouciantly explored.