The response of the rat soleus muscle to tenotomy after dorsal root section

Both soleus muscles of rats were tenotomized 5-10 days after deafferentation of one side which was achieved by section of the 4th and 5th lumbar dorsal roots. When examined 2 weeks after tenotomy, all experimental muscles showed central degenerative changes in slow fatigue-resistant fibers. These changes were absent from muscles that had been only deafferented. Experimental deafferented muscles examined 6 weeks after tenotomy showed a substantial recovery which was comparable to that seen in tenotomized muscles with intact afferent innervation. It is concluded that (1) deafferentation does not inhibit the recovery of tenotomized fibers, and (2) the loss of afferent fibers plays no part in the protection from central degeneration known to be afforded by denervation of tenotomized muscles.