title: High-dose antioxidant vitamin C supplementation does not prevent acute exercise-induced increases in markers of skeletal muscle mitochondrial biogenesis in rats.
abstract: High doses of the antioxidant vitamin C prevent the increases in skeletal muscle mitochondrial biogenesis after exercise training. Since exercise training effects rely on the acute stimulus of each exercise bout, we examined whether vitamin C supplementation also attenuates the increases in skeletal muscle metabolic signaling and mitochondrial biogenesis in response to an acute exercise bout. Male Sprague-Dawley rats performed 60 min of treadmill running (27 m/min, 5% grade) or remained sedentary. For 7 days before this, one-half of the rats received water containing 500 mg/kg body wt vitamin C. Acute exercise significantly (P<0.05) increased the phosphorylation of p38 MAPK, AMP-activated kinase-alpha, and activating transcription factor (ATF)-2 and the ratio of oxidized to total glutathione (GSSG/TGSH) in the gastrocnemius. However, vitamin C had no effect on these increases. Similarly, vitamin C did not prevent the exercise-induced increases in peroxisome proliferator-activated receptor-gamma coactivator-1alpha, nuclear respiratory factor (NRF)-1, NRF-2, mitochondrial transcription factor A, glutathione peroxidase-1, MnSOD, extracellular SOD, or glucose transporter 4 (P<0.05) mRNA after exercise. Surprisingly, vitamin C supplementation significantly increased the basal levels of GSSG/TGSH, NRF-1, and NRF-2 mRNA and basal ATF-2 phosphorylation. In summary, despite other studies in rats showing that vitamin C supplementation prevents increases in skeletal muscle mitochondrial biogenesis and antioxidant enzymes with exercise training, vitamin C had no affect on the acute exercise-induced increases of these markers.
authors.affiliation: Department of Physiology, The University of Melbourne, Parkville, Victoria, Australia. glenn.wadley@deakin.edu.au
authors.forename: G D
authors.initials: GD
authors.lastname: Wadley
authors.forename: G K
authors.initials: GK
authors.lastname: McConell
mesh_terms: D000818:Animals; D001205:Ascorbic Acid / Q000008:administration & dosage*; D015415:Biomarkers / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D008297:Male; D008928:Mitochondria / Q000187:drug effects / Q000502:physiology*; D024101:Mitochondrial Proteins / Q000378:metabolism*; D009124:Muscle Proteins / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D010805:Physical Conditioning, Animal / Q000379:methods*; D005082:Physical Exertion / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D015415:Biomarkers; D024101:Mitochondrial Proteins; D009124:Muscle Proteins; D001205:Ascorbic Acid