Mice genetically engineered to produce a human antioxidant enzyme lived longer than normal mice, which U.S. scientists Thursday cited as evidence that antioxidants can counteract the effects of aging and disease.
Chemicals known as free radicals damage cells by generating a reaction called oxidation -- the same process that causes metal to rust. Antioxidants interfere with this chemical reaction.
Writing in the journal Science, Dr. Peter Rabinovitch and colleagues at the University of Washington School of Medicine said they helped show free radicals can damage cells and DNA.
The researchers used genetically engineered mice that made extra amounts of catalase, an antioxidant enzyme that helps break down hydrogen peroxide into water and oxygen.
Hydrogen peroxide is produced during metabolism and it can be a precursor of free radicals.
The mice were precisely designed to produce extra catalase in certain areas of the body -- the cells’ cytoplasm; the nucleus where DNA is stored; and the mitochondria, the cell’s power plant and also a place where some DNA is found.
Significance of free radicals
The mice that made more catalase in the mitochondria lived about 20 percent longer -- about five months. The mice with more catalase levels in the nucleus and cytoplasm lived only a little longer than normal mice.
The mice with catalase in the mitochondria also had healthier heart muscle tissue, indicating the catalase helped protect from age-related heart problems seen in normal mice.
“This study is very supportive of the free-radical theory of aging,” Rabinovitch said in a statement. “It shows the significance of free radicals, and of reactive oxygen species in particular, in the aging process.”
It also supports the idea that the mitochondria produce many of these damaging free radicals as part of everyday metabolism.
The findings could be used as a basis for drugs or other treatments that protect the body from free radicals and perhaps some age-related conditions, Rabinovitch said.
“People used to only focus on specific age-related diseases, because it was believed that the aging process itself could not be affected,” Rabinovitch said.
“What we’re realizing now is that by intervening in the underlying aging process, we may be able to produce very significant increases in ’healthspan,’ or healthy lifespan.”