Extracorporeal shock waves promote the repair of injured muscle tissue by regulating insulin-like growth factor-1 and phosphorylated protein kinase B levels / 中华物理医学与康复杂志

ABSTRACT

Objective:To determine whether or not shock wave therapy promotes the repair of muscle injury by regulating insulin-like growth factor-1 (IGF-1) and/or the phosphorylation of protein kinase B (p-Akt).Methods:Sixty-six adult male Sprague-Dawley rats were randomly divided into a normal group, a model group and a treatment group. A custom-made striker was used to induce blunt contusion in the gastrocnemius muscles of the rats of the model and treatment groups. The normal and model groups were then not given any therapeutic intervention. Twenty-four hours later, the treatment group underwent 500-impulse shockwave treatment at 0.14mJ/mm 2 and 10Hz. That was repeated 4 days later. The injured muscle was sampled on the 1st, 3rd, 5th, and 7th day after modeling. Hematoxylin and eosin staining was applied to observe the arrangement of muscle fibers, and the expressions of myostatin, myogenic differentiation antigen 1 (MYOD1), IGF-1 and p-AKTs473 were detected by immunohistochemistry and western blotting. Results:(1) The staining showed that in the model group the space between the muscle cells was larger than in the normal group. In the treatment group there were more newly-formed mononuclear or multinucleated muscle tubes. The regeneration of skeletal muscle in the treatment group was superior to that in the model group at the same time points. (2) The average myostatin expression of the model group increased significantly compared with the normal group at all the time points, while that of the treatment group had decreased significantly compared with the model group. Moreover, no significant differences were found on the 7th day between the treatment and normal groups. (3) Western blotting showed that the expression of MyoD1 in the model group was significantly higher than that in the normal group on days 1 and 3, and the expression of MyoD1 in the treatment group was significantly higher than in the model group. The expression levels of IGF-1 and P-AKTS473 in the model group were higher than those in the normal group at the same time point, and the expression levels in the treatment group were significantly higher than those in the model group.Conclusion:Extracorporeal shock wave therapy can promote the regeneration and repair of skeletal muscle by regulating IGF-1 and p-AKT levels.