We examined the effect of voluntary exercise on antioxidant enzyme activities (catalase, glutathione peroxidase, superoxide dismutase) in skeletal muscle (hind- and forelimb) and heart of a model small mammal species: short-tailed field vole Microtus agrestis. In addition, DNA oxidation was determined in lymphocytes and hepatocytes using the comet assay and lipid peroxidation estimated in hindlimb muscle by measurement of thiobarbituric-acid-reactive substances. Voles (approximately 6 weeks old), exposed to a 16L:8D photoperiod (lights on 0500 h), ran almost continuously during darkness. We studied the effects of voluntary running over 1 or 7 days duration, with or without an 8-h rest period, on various biomarkers of oxidative stress compared to nonrunning controls. No differences were observed in antioxidant enzyme activities, except in heart total superoxide dismutase activity (P=0.037), with the lowest levels in 1- and 7-day runners at 0500 h. DNA oxidative damage, in lymphocytes or hepatocytes, and lipid peroxidation did not differ between groups. There was no evidence of any significant increase in any oxidative stress parameter in running individuals, despite having significantly elevated energy expenditures compared to sedentary controls.
(c) 2002 Elsevier Science (USA).