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Oxidative stress to DNA increases with age, study finds
(08-22-01)
The older a rodent is, the greater the chance that its genes have been
damaged by oxidation. That's the conclusion of a study conducted at The
University of Texas Health Science Center at San Antonio (UTHSC) and published
in the Aug. 21 issue of the Proceedings of the National Academy of
Sciences-USA.
The researchers compared levels of a key stress marker, 8-oxo-2-deoxyguanosine
(oxo8dG), in rats and mice of various ages. The scientists scanned liver,
kidney, brain, heart and muscle tissue, finding that the older the rat
or mouse, the higher the level of the marker. Oxo8dG is described as a
modification of a genetic sequence.
One theory of aging is that oxidants are generated during normal metabolism
and can react with DNA, the genetic code, causing damage. The body continuously
repairs its own DNA, but any oxidative lesion that is not repaired can
lead to mutations, increasing the risk of cancer.
This study suggests that the age-related increase in oxidative lesions
in DNA could be an important factor in the age-related increase in most
cancers. Age is well documented to be the leading risk factor for most
cancers.
The study was part of a Ph.D. dissertation written by Michelle Hamilton,
a graduate student in the UTHSC department of physiology, with assistance
from her mentor, Arlan G. Richardson, Ph.D., and other faculty members
in the Sam and Ann Barshop Center on Longevity and Aging Studies, the
departments of physiology and cellular and structural biology, and the
Geriatric Research, Education and Care Center at the South Texas Veterans
Health Care System, Audie Murphy Division.
Contact: Will Sansom