Functional overloading facilitates the regeneration of injured skeletal muscles

Abstract

Muscle satellite cells have been considered to play an important role in postnatal growth and the regeneration of skeletal muscle. Recently it has been suggested that the activation of muscle satellite cells is also associated with muscle hypertrophy. Therefore, the regenerative process of injured muscles may be facilitated by the activation of muscle satellite cells induced by various hypertrophic stimuli. The purpose of this study was to investigate the effects of overloading on the regenerative process of injured skeletal muscle in mice. Male mice (C57BL/6J) were divided randomly into four groups: (1) cage control (CC), (2) cardiotoxin-injected (CX), (3) functional-overloaded (FO) and (4) CX+FO groups. In the groups of FO with and without CX, overloading on soleus of both hindlimbs was performed by cutting the distal tendons of both plantaris and gastrocnemius muscles. Two weeks after the surgery, cardiotoxin was injected into soleus muscles of both limbs in CX and CX+FO groups. Soleus muscles were dissected 14, 28 and 35 days after cardiotoxin-injection. Responses of muscular protein contents and Pax7-positive muscle satellite cells during the regeneration were analyzed. Evidences suggest that functional overloading may facilitate the regeneration of injured skeletal muscles. [J Physiol Sci. 2006;56 Suppl:S144]