Abstract
Influence of muscle inactivity on the regenerative process of injured skeletal muscle was studied. Male mice (C57BL/6J) were randomly divided into 4 groups; normal cage control (CC), cardiotoxin (CTX)-injected (CX), hindlimb suspension (HS), and HS+CX (SX) groups. HS was performed for 2 weeks in group HS and SX. And then, CTX was injected into soleus muscles bilaterally in CX and SX groups. HS was continued for additional 6 weeks in group HS and SX. CTX-injection caused a decrease in wet weight and protein content of soleus. Both muscle weight and protein content in group CX recovered to the control level following 4 weeks. On the contrary, both parameters in group SX did not recover during the experimental period. Percentage of fibers with central nuclei, relative to total muscle fibers, in CX group at 42 days was higher than in SX group. It was suggested that loading plays a key role for the activation of regenerating potential of injured skeletal muscle. (Supported, in part, by Grant-in-Aid for Scientific Research (C, 17500444; A, 18200042; S, 19100009) from Japan Society for the Promotion of Science, Ground-based Research Program for Space Utilization from Japan Space Forum). [J Physiol Sci. 2008;58 Suppl:S67]
