Repetitive stretch suppresses denervation-induced atrophy of soleus muscle in rats

Muscle Nerve. 2009 Apr;39(4):456-62. doi: 10.1002/mus.21103.

Abstract

This study was conducted to examine whether stretch-related mechanical loading on skeletal muscle can suppress denervation-induced muscle atrophy, and if so, to depict the underlying molecular mechanism. Denervated rat soleus muscle was repetitively stretched (every 5 s for 15 min/day) for 2 weeks. Histochemical analysis showed that the cross-sectional area of denervated soleus muscle fibers with repetitive stretching was significantly larger than that of control denervated muscle (P<0.05). We then examined the involvement of the Akt/mammalian target of the rapamycin (mTOR) cascade in the suppressive effects of repetitive stretching on muscle atrophy. Repetitive stretching significantly increased the Akt, p70S6K, and 4E-BP1 phosphorylation in denervated soleus muscle compared to controls (P<0.05). Furthermore, repetitive stretching-induced suppression of muscle atrophy was fully inhibited by rapamycin, a potent inhibitor of mTOR. These results indicate that denervation-induced muscle atrophy is significantly suppressed by stretch-related mechanical loading of the muscle through upregulation of the Akt/mTOR signal pathway.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Carrier Proteins / metabolism
  • Immunosuppressive Agents / pharmacology
  • Intracellular Signaling Peptides and Proteins
  • Male
  • Muscle Denervation
  • Muscle Stretching Exercises*
  • Muscle, Skeletal* / innervation
  • Muscle, Skeletal* / metabolism
  • Muscle, Skeletal* / physiopathology
  • Muscular Atrophy / metabolism*
  • Muscular Atrophy / physiopathology*
  • Phosphoproteins / metabolism
  • Phosphorylation / drug effects
  • Phosphorylation / physiology
  • Protein Kinases / metabolism
  • Proto-Oncogene Proteins c-akt / metabolism
  • Rats
  • Rats, Wistar
  • Ribosomal Protein S6 Kinases, 70-kDa / metabolism
  • Signal Transduction / drug effects
  • Signal Transduction / physiology*
  • Sirolimus / pharmacology
  • Stress, Mechanical
  • TOR Serine-Threonine Kinases
  • Up-Regulation / physiology
  • Weight-Bearing / physiology*

Substances

  • Carrier Proteins
  • Eif4ebp1 protein, rat
  • Immunosuppressive Agents
  • Intracellular Signaling Peptides and Proteins
  • Phosphoproteins
  • Protein Kinases
  • mTOR protein, rat
  • Proto-Oncogene Proteins c-akt
  • Ribosomal Protein S6 Kinases, 70-kDa
  • TOR Serine-Threonine Kinases
  • Sirolimus