Effect of Exercise Training after Partial Denervation in Rat Soleus Muscles

Abstract

Although functional recovery in skeletal muscle after partial denervation has been an object of study for a long time, little agreement has been reached regarding the effect of exercise training on skeletal muscle after partial denervation. The present study examined the effects of exercise training after partial denervation. We developed a rat model for partial denervation of the soleus muscle by resecting the fifth lumbar vertebral nerve on one side. The central side of the fifth lumbar vertebral nerve was ligated to inhibit regeneration of the resected nerve. Animals were exercised on a treadmill for 2 or 6 weeks. We measured muscle mass, muscle fiber-type ratio and cross-sectional area of muscle fibers in the soleus muscle after transection of the tibial nerve. Muscle mass and muscle fiber-type ratios were unchanged. Partially denervated tibial nerves displayed local degeneration up to 6 weeks. Muscle fiber area was significantly higher for exercised soleus muscle after partial denervation than for spontaneous recovery at 2 weeks. At 6 weeks, spontaneously recovered muscles had returned to control levels, while exercised muscle displayed increased growth compared with control muscle. Mechanical stimulation appears to prevent muscle atrophy in the soleus muscle after partial denervation. These results suggest that exercise therapy after partial denervation is effective.