The more active rats were found to have fewer byproducts of oxidative stress in their brains. Fats known as lipids that help stabilize cell membranes, and DNA, the molecule that contains our genetic blueprint, both better withstood the rigors of time.
"The DNA for these animals after two years looked as if it were from their younger counterparts of only about 6 months of age," Foster said. "It shows a little bit of exercise may stimulate the body to fight stress that's normally occurring in the brain."
Damage to DNA causes cell mutations and cell death. Finding ways to preserve it may help prevent age-related memory loss and defend against deterioration of balance and motor function -- important health goals as the U.S. population continues to age. The 2000 Census shows 34.9 million Americans are 65 or older. That amount is projected to grow to 47 million by 2020.
"There have been implications that exercise is beneficial for preventing neurological diseases and aging impairments, but these studies put a molecular imprint on what might be happening," said Eric Klann, Ph.D., a professor of molecular physiology and biophysics at the Baylor College of Medicine who is not connected to the research.
"The difference between humans and rats is that it isn't as easy to get humans to exercise," Klann added. "Put an exercise wheel in a rat cage and a rat will zoom around on that thing all the time, unless it's sleeping. But putting an exercise machine in your family room doesn't mean you're going to use it."
The next step in the research is to determine which natural chemicals and mechanisms are triggered by exercise to fight oxidative stress, and to test whether reducing the stress actually improves brain function.
"By age 50 almost everyone has mild memory deficits," Foster said. "We forget where we put the keys or jumble the names of our kids. If t
Contact: John Pastor
University of Florida