Meeting Abstract

P2.175  Saturday, Jan. 5  Antioxidant enzymes: Acute and chronic responses to exercise-induced oxidative stress in gastrocnemius muscle of mice OLSON, JM*; KEARNEY, C.; RIVERA, G.; Villanova University john.olson@villanova.edu

High aerobic fluxes during sustained exercise increases generation of reactive oxygen species (ROS) such as superoxide ions, peroxides, and hydroxyl radicals. High ROS levels can have a wide range of deleterious effects in the cell, disrupting redox balance and reacting with and degrading the integrity of nucleic acid, protein, and lipid. This potential for damaging impacts is a strong selective force for developing effective and broad scale cellular defenses. In addition to antioxidants such as vitamins C and E and glutathione, mammals possess several antioxidant enzymes, including superoxide dismutase isoenzymes located primarily in the cytoplasm (SOD1) and mitochondrion (SOD2), and the glutathione peroxidase (GPx) family of enzymes that work in conjunction with SOD by reducing hydrogen peroxide. This study tests the hypotheses that (1) gastrocnemius muscles of trained mice have lower oxidative stress than their untrained counterparts owing to upregulation of key antioxidant enzymes; (2) mitochondrial (mt) forms of SOD and GPx will be especially affected; and (3) the patterns of transcription will vary with training. Trained mice were swum daily for 5 d/week for 2 or 6 weeks; swims lasted 1 h/d for first 2 weeks, then were increased by 15 min/d every two weeks. To induce oxidative stress on day of sampling, mice were swum for 1 h and compared to a subset not swum. Samples were collected at two additional times (5h, 24h) after the swim to assess recovery and patterns of transcription. Oxidative stress in gastrocnemius muscle (measured as level of lipid peroxidation/malondialdehyde) was significantly higher in untrained than trained mice. Levels of mRNA transcripts (assessed with qPCR) of SOD1, SOD2, GPx1, GPx4 (mt), and GPx4 (cytoplasmic) will be discussed.