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Increased antioxidant capacity reverses some effects of aging

by Ross Tomlin

	Eric Klann, Ph.D.

Free radicals and other chemicals damage cells through a chemical process called oxidation. Now researchers at Baylor College of Medicine have found that increasing the amount of an antioxidant enzyme can reverse declining memory skills and other pathological effects of old age. The findings appear in a recent issue of Journal of Neuroscience.

"This is one of the first studies showing that a genetically engineered mouse that overexpresses (or produces more than normal amounts of) an antioxidant enzyme actually performs better as the animal ages with respect to memory," said Eric Klann, Ph.D., professor of molecular physiology and biophysics at BCM. Klann was principal investigator of the study.

The study is one of the first to assess memory performance among aging mice that were genetically engineered to produce an abundance of an antioxidant enzyme called extracellular superoxide dismutase. As these mice aged, they performed better on memory tasks and demonstrated cellular improvements in the hippocampus, a part of the brain required for memory.

Conversely, the same experiments in younger mice showed that high levels of the antioxidant were detrimental to memory function.

Previous studies have concluded that oxidative stress contributes to aging and aging-related impairments in memory. Klann conjectures that high antioxidant levels, within reason, could promote longevity and reduce the risk of dementia associated with normal aging and neurodegenerative disorders such as Alzheimer's disease.

Klann's study advances the debate over the value of antioxidant supplements, which some claim eliminate hazardous free radicals from the body and reduce the risk of cancer, among other disorders. On the other hand, recent reports claim that excessive intake of vitamin and mineral supplements pose no benefit and can even do harm in some cases.

"The balance of oxidants is very important," said Klann. "In animal studies, it's bad to have too much or too little. That could be part of the reason for conflicting findings on antioxidant supplements in humans."

Klann says further research in mice will be necessary to approximate ideal antioxidant levels and whether antioxidant enzymes can prevent dementia and other aging-related impairments.

Daoying Hu and Faridis Serrano, Ph.D., at BCM and Tim D. Oury, Ph.D., at the University of Pittsburgh Medical Center also contributed to this paper. The study was funded by the National Institutes of Health and the Cynthia and George Mitchell Foundation.

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