OXIDATIVE STRESS AND AGING IN THE MONGOLIAN GERBIL (MERIONES-UNGUICULATUS)

The objective of this study was to determine if aging in the gerbil, M eriones unguiculatus, is associated with elevation in the level of oxi dative stress. Studies were conducted on the brain, heart, kidney, liv er and testis of young (3-6 months), adult (15 months), and old (23-25 months) animals. Oxidative damage to proteins, measured as the concen tration of protein carbonyls and loss of activity of glucose-6-phospha te dehydrogenase, and to DNA, measured as the concentration of 8-hydro xydeoxyguanosine, increased with age of the animals. There was no appr eciable age-related change in the activity of alkaline proteases, whic h preferentially degrade oxidized protein. Rates of mitochondrial supe roxide anion radical and hydrogen peroxide generation also increased w ith age, most notably in the heart. Antioxidative defenses, measured a s activities of superoxide dismutase, catalase and glutathione peroxid ase and concentration of glutathione, did not exhibit a uniform patter n of age-related changes. However, when the antioxidative potential of the tissue homogenates was measured as their susceptibility to underg o protein oxidation, in response to experimentally-induced oxidative s tress, using X-irradiation, tissues of the old animals were significan tly more vulnerable than those of the young animals. Results of this s tudy are interpreted to indicate: (i) that the level of molecular oxid ative damage to DNA and proteins increases with age, and (ii) that the increased oxidative damage is due to both an, elevation in the rates of oxidant generation and an increase in the susceptibility of tissues to oxidative damage.