Endurance training alters antioxidant enzyme gene expression in rat skeletal muscle

The effects of endurance training on gene expression of superoxide dismutas e (SOD) and glutathione peroxidase (GPX) were investigated in type 2a and 2 b skeletal muscles, as well as heart and liver, in the rat. Female Sprague- Dawley rats (4 months old, 300-320 g) were randomly divided into a trained (T, n = 11) and a control (C, n = 10) group and were pair fed a diet consis ting of 66% cornstarch and 34% basal diet that contained all essential nutr ients. Training was conducted on a treadmill at 25 m . min(-1), 10% grade f or 2 h per day, 5 days per week for 10 weeks, resulting in a 79% (p < 0.01) increase in citrate synthase activity in the deep portion of vastus latera lis muscle (DVL, type 2a). Cu-Zn SOD activity was 35% higher (p < 0.01) in DVL of T versus C rats, and Cu-Zn SOD mRNA abundance showed a 125% increase with training (p < 0.05). Cu-Zn SOD protein content was not altered in DVL , but increased significantly (p < 0.05) in the superficial portion of vast us lateralis (type 2b) with training. Trained rats showed a 66% higher (p < 0.05) Mn SOD protein content in DVL, but Mn SOD activity and mRNA abundanc e were not affected. Training also significantly increased GPX activity by 62% (p < 0.05), without changing its mRNA abundance, in the DVL. Heart and liver showed a 112 and 58% increase (p < 0.01) in Cu-Zn SOD mRNA abundance with training, respectively, but no other training adaptation was detected. These data indicate that endurance training can promote gene expression of muscle antioxidant enzymes in a fiber-specific manner. Training appears to upregulate Cu-Zn SOD mRNA abundance in a number of aerobic tissues, wherea s Mn SOD and GPX induction observed in DVL may occur at the post-transcript ional levels.