Antioxidant Supplementation Reduces Skeletal Muscle Mitochondrial Biogenesis NATALIE A. STROBEL 1 , JONATHAN M. PEAKE 1 , AYA MATSUMOTO 1 , SUSAN A. MARSH 2 , JEFF S. COOMBES 1 , and GLENN D. WADLEY 3,4 1 School of Human Movement Studies, The University of Queensland, St. Lucia, Queensland, AUSTRALIA; 2 Program in Nutrition and Exercise Physiology, Washington State University, Spokane, WA; 3 Department of Physiology, The University of Melbourne, Parkville, Victoria, AUSTRALIA; and 4 Centre for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Burwood, Victoria, AUSTRALIA ABSTRACT STROBEL, N. A., J. M. PEAKE, A. MATSUMOTO, S. A. MARSH, J. S. COOMBES, and G. D. WADLEY. Antioxidant Supple- mentation Reduces Skeletal Muscle Mitochondrial Biogenesis. Med. Sci. Sports Exerc., Vol. 43, No. 6, pp. 1017–1024, 2011. Purpose: Exercise increases the production of reactive oxygen species (ROS) in skeletal muscle, and athletes often consume antiox- idant supplements in the belief they will attenuate ROS-related muscle damage and fatigue during exercise. However, exercise-induced ROS may regulate beneficial skeletal muscle adaptations, such as increased mitochondrial biogenesis. We therefore investigated the effects of long-term antioxidant supplementation with vitamin E and >-lipoic acid on changes in markers of mitochondrial biogenesis in the skeletal muscle of exercise-trained and sedentary rats. Methods: Male Wistar rats were divided into four groups: 1) sedentary control diet, 2) sedentary antioxidant diet, 3) exercise control diet, and 4) exercise antioxidant diet. Animals ran on a treadmill 4dIwk j1 at È70%V ˙ O 2max for up to 90 minId j1 for 14 wk. Results: Consistent with the augmentation of skeletal muscle mito- chondrial biogenesis and antioxidant defenses, after training there were significant increases in peroxisome proliferator–activated receptor F coactivator 1> (PGC-1>) messenger RNA (mRNA) and protein, cytochrome C oxidase subunit IV (COX IV) and cyto- chrome C protein abundance, citrate synthase activity, Nfe2l2, and SOD2 protein (P G 0.05). Antioxidant supplementation reduced PGC-1> mRNA, PGC-1> and COX IV protein, and citrate synthase enzyme activity (P G 0.05) in both sedentary and exercise-trained rats. Conclusions: Vitamin E and >-lipoic acid supplementation suppresses skeletal muscle mitochondrial biogenesis, regardless of training status. Key Words: >-LIPOIC ACID, EXERCISE TRAINING, MITOCHONDRIA, Nfe2l2, PGC-1>, VITAMIN E A growing body of evidence highlights an important role for exercise-induced reactive oxygen species (ROS) in regulating cell signaling processes that contribute to adaptations in skeletal muscle after exercise training (1,10,14,30). One such process is mitochondrial bio- genesis, a complex pathway resulting in an increase in mi- tochondrial content and density. This process is one of the main adaptations that occur in skeletal muscle after endurance exercise training. A central factor regulating mitochondrial biogenesis is peroxisome proliferator–activated receptor F coactivator 1> (PGC-1>) (13,28). PGC-1> coactivates the transcription factors nuclear respiratory factors 1 and 2 (NRF-1 and -2), which regulate nuclear encoded genes within the mitochondria. NRF-1 regulates mitochondrial transcrip- tion factor A (Tfam), which, in turn, controls mitochondrial DNA replication and transcription (13,28). Downstream, PGC-1>, NRF-1 and -2, and Tfam upregulate the expression and activity of key mitochondrial proteins; these include key proteins controlling oxidative phosphorylation (e.g., cyto- chrome C and cytochrome C oxidase subunit IV (COX IV)), proteins involved in the Krebs cycle (e.g., citrate synthase) and enzymes involved in fatty acid oxidation (e.g., A- hydroxyacyl-CoA dehydrogenase (A-HAD)). Collectively, increases in these markers of mitochondrial biogenesis (PGC-1>, NRF-1 and -2, and Tfam) and mitochondrial pro- teins (COX IV, cytochrome C, citrate synthase, and A-HAD) are associated with elevated mitochondrial content after ex- ercise training (28,35). Antioxidants inhibit skeletal muscle ROS, and recent evi- dence indicates that they attenuate cell signaling processes that are important for skeletal muscle adaptations to exercise training (10,30). Acute and chronic contractions of skeletal muscle cells ex vivo stimulate increased gene expression of PGC-1>; however, various antioxidants, including the com- bination of vitamin E, vitamin C, and coenzyme Q 10 , block this effect (31). Furthermore, in vivo rat studies support this outcome as long-term supplementation of vitamin C attenu- ates exercise training–induced increases in markers of mito- chondrial biogenesis, such as the protein and gene expression Address for correspondence: Glenn D. Wadley, Ph.D., Centre for Physi- cal Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, 221 Burwood Hwy, Burwood, 3125, Australia; E-mail: glenn.wadley@deakin.edu.au. Submitted for publication August 2010. Accepted for publication October 2010. 0195-9131/11/4306-1017/0 MEDICINE & SCIENCE IN SPORTS & EXERCISE Ò Copyright Ó 2011 by the American College of Sports Medicine DOI: 10.1249/MSS.0b013e318203afa3 1017 BASIC SCIENCES Copyright © 2011 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited.