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Mitochondrial Apoptotic Signaling is Elevated in Cardiac but Not Skeletal Muscle in the Obese Zucker Rat and is Reduced with Aerobic Exercise
American Physiological Society (2008)
  • Jonathan M. Peterson, West Virginia University School of Medicine
  • Randall W. Bryner, West Virginia University School of Medicine
  • Amy Sindler, West Virginia University School of Medicine
  • Jefferson C. Frisbee, West Virginia University School of Medicine
  • Stephen E. Alway, West Virginia University School of Medicine
Abstract
Mitochondrial apoptosis and apoptotic signaling modulations by aerobic training were studied in cardiac and skeletal muscles of obese Zucker rats (OZR), a rodent model of metabolic syndrome. Comparisons were made between left ventricle, soleus, and gastrocnemius muscles from OZR (n = 16) and aged-matched lean Zucker rats (LZR; n = 16) that were untrained (n = 8) or aerobically trained on a treadmill for 9 wk (n = 8). Cardiac Bcl-2 protein expression levels were ∼50% lower in the OZR compared with the LZR, with no difference in either of the skeletal muscles. Bax protein expression levels were similar in skeletal muscles of the OZR compared with the LZR. Furthermore, mitochondrial apoptotic signaling was not different in skeletal muscles of OZR and LZR groups. However, there was an approximate sevenfold increase in the Bax protein accumulation in the myocardial mitochondrial-rich protein fraction of the OZR compared with the LZR. Additionally, there was an increase in cytosolic cytochrome c released from the mitochondria, caspase-9 and caspase-3 activity, with a corresponding elevation in DNA fragmentation in the cardiac muscles of the OZR compared with the LZR. Exercise training reduced cardiac Bax protein levels, the mitochondrial localization of Bax, cytosolic cytochrome c, caspase activity, and DNA fragmentation in cardiac muscles of the OZR after exercise, with no change in the skeletal muscles. These data show that mitochondrial apoptosis is elevated in the cardiac but not skeletal muscles of the OZR, but aerobic exercise training was effective in reducing cardiac mitochondrial apoptotic signaling.
Keywords
  • mitochondrial,
  • apoptotic,
  • signaling,
  • cardiac muscle,
  • skeletal muscle,
  • obese,
  • zucker rate,
  • aerobic exercise
Publication Date
December 1, 2008
DOI
10.1152/japplphysiol.00037.2008
Citation Information
Jonathan M. Peterson, Randall W. Bryner, Amy Sindler, Jefferson C. Frisbee, et al.. "Mitochondrial Apoptotic Signaling is Elevated in Cardiac but Not Skeletal Muscle in the Obese Zucker Rat and is Reduced with Aerobic Exercise" American Physiological Society Vol. 105 Iss. 6 (2008) p. 1934 - 1943 ISSN: 1522-1601
Available at: http://works.bepress.com/jonathan-peterson/18/