Effects of denervation and deafferentation on mass and enzyme activity in rat skeletal muscles

Effects of denervation and deafferentation on mass and enzyme activity of soleus and plantaris muscles were studied when the synergistic gastrocnemius was either intact or tenotomized in adult male Wistar rats. Denervation of the sciatic nerve at L4 and L5 induced a severe atrophy (approximately 50%) in both soleus and plantaris within 2 weeks. Deafferentation at L4 and L5 also caused a decrease in muscle weight for soleus and plantaris (approximately 11 and 24%, respectively). No compensatory response to the tenotomy was induced either for muscle weight or enzyme activity in both denervated and deafferentated muscles. It is suggested that the efferent information(s) through the nerve fibers has an important effect of the regulation of both muscle mass and enzyme activity. Its effect on the activities was greater in mitochondrial than cytoplasmic enzymes. The data also suggest that the afferent information(s) plays a significant role for the regulation of muscle mass, including an induction of compensatory hypertrophy, but not for enzyme activity.