title: PGC-1α mediates a rapid, exercise-induced downregulation of glycogenolysis in rat skeletal muscle.
abstract: CONCLUSIONS
  Long-term endurance exercise training results in a reduction in the rates of muscle glycogen depletion and lactic acid accumulation during submaximal exercise; this adaptation is mediated by an increase in muscle mitochondria. There is evidence suggesting that short-term training induces adaptations that downregulate glycogenolysis before there is an increase in functional mitochondria. We discovered that a single long bout of exercise induces decreases in expression of glycogenolytic and glycolytic enzymes in rat skeletal muscle; this adaptation results in slower rates of glycogenolysis and lactic acid accumulation in muscle during contractile activity. Two additional days of training amplified the adaptive response, which appears to be mediated by PGC-1α; this adaptation is biologically significant, because glycogen depletion and lactic acid accumulation are major causes of muscle fatigue.
  Endurance exercise training can increase the ability to perform prolonged strenuous exercise. The major adaptation responsible for this increase in endurance is an increase in muscle mitochondria. This adaptation occurs too slowly to provide a survival advantage when there is a sudden change in environment that necessitates prolonged exercise. In the present study, we discovered another, more rapid adaptation, a downregulation of expression of the glycogenolytic and glycolytic enzymes in muscle that mediates a slowing of muscle glycogen depletion and lactic acid accumulation. This adaptation, which appears to be mediated by PGC-1α, occurs in response to a single exercise bout and is further enhanced by two additional daily exercise bouts. It is biologically significant, because glycogen depletion and lactic acid accumulation are two of the major causes of muscle fatigue and exhaustion.
authors.affiliation: Division of Geriatrics and Nutritional Sciences, Section of Applied Physiology, Department of Medicine, Washington University School of Medicine, 4566 Scott Avenue, Campus Box 8113, St Louis, MO, 63110, USA.
authors.forename: Sang Hyun
authors.initials: SH
authors.lastname: Kim
authors.forename: Jin Ho
authors.initials: JH
authors.lastname: Koh
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Higashida
authors.forename: Su Ryun
authors.initials: SR
authors.lastname: Jung
authors.forename: John O
authors.initials: JO
authors.lastname: Holloszy
authors.forename: Dong-Ho
authors.initials: DH
authors.lastname: Han
mesh_terms: D000818:Animals; D015536:Down-Regulation; D006003:Glycogen / Q000378:metabolism; D050261:Glycogenolysis; D019344:Lactic Acid / Q000378:metabolism; D008297:Male; D018763:Muscle Fatigue; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000502:physiology; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D005082:Physical Exertion; D051381:Rats; D017208:Rats, Wistar; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; C501429:Ppargc1a protein, rat; D014157:Transcription Factors; D019344:Lactic Acid; D006003:Glycogen