Decreased DNA fragmentation and apoptotic signaling in soleus muscle of hypertensive rats following 6 weeks of treadmill training

J Appl Physiol (1985). 2012 Oct;113(7):1048-57. doi: 10.1152/japplphysiol.00290.2012. Epub 2012 Aug 2.

Abstract

Cardiovascular diseases such as hypertension are associated with a generalized skeletal myopathy including a proapoptotic phenotype. Current evidence suggests that exercise may alter apoptosis-related signaling in skeletal muscle; however, the effect of exercise on skeletal muscle DNA fragmentation and apoptotic signaling is unclear in hypertensive animals. Male normotensive Wistar Kyoto (WKY; n = 24) and spontaneously hypertensive rats (SHR; n = 24) were assigned to a sedentary (SED) condition or exercise (EX) consisting of progressive treadmill running 5 days/wk for 6 wks. Consistent with our previous work we found that soleus muscle of hypertensive animals had significantly higher DNA fragmentation (a hallmark of apoptosis), elevated proapoptotic factors (Bax, caspase-3 activity), and lower antiapoptotic proteins (apoptosis repressor with caspase recruitment domain, Bcl-2, X-linked inhibitor of apoptosis protein) compared with normotensive rats. In addition, soleus muscle of hypertensive animals displayed myosin accumulation and fragmentation, had elevated cytosolic cytochrome c, second mitochondrial-derived activator of caspase (Smac), apoptosis inducing factor (AIF), and endonuclease G protein levels, higher nuclear AIF content, and greater muscle reactive oxygen species generation compared with normotensive animals. Interestingly, exercise training significantly lowered DNA fragmentation and myosin accumulation/fragmentation in soleus muscle of hypertensive rats. Furthermore, exercise training significantly reduced cytosolic levels of cytochrome c as well as cytosolic and nuclear AIF in soleus muscle of hypertensive animals. This beneficial response is likely due to exercise-mediated elevations in Bcl-2, heat shock protein 70, and manganese superoxide dismutase protein content, as well as reductions in Bax protein levels and the Bax-to-Bcl-2 ratio. These results suggest that regular exercise training provides protection against skeletal muscle apoptosis by altering a number of apoptosis regulatory proteins and by influencing mitochondrial-mediated apoptotic signaling mechanisms.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antioxidants / metabolism
  • Apoptosis / physiology*
  • Apoptosis Regulatory Proteins / metabolism*
  • DNA Fragmentation*
  • Education / methods
  • Exercise Test / methods
  • Hypertension / metabolism
  • Hypertension / physiopathology*
  • Male
  • Muscle, Skeletal / metabolism
  • Muscle, Skeletal / physiology*
  • Muscle, Skeletal / physiopathology
  • Myosins / metabolism
  • Physical Conditioning, Animal / methods
  • Rats
  • Rats, Inbred SHR
  • Rats, Inbred WKY
  • Rats, Wistar
  • Reactive Oxygen Species / metabolism

Substances

  • Antioxidants
  • Apoptosis Regulatory Proteins
  • Reactive Oxygen Species
  • Myosins