Abstract:Objective: To investigate the effect of extracorporeal shock wave (ESW) on repair of skeletal muscle injury, so as to provide theoretical basis for clinical application of ESW in the treatment of skeletal muscle disease. Methods: A model of skeletal muscle blunt contusion was established, and the experiment was divided into the ESW group and the injury group. The ESW group were treated with ESW on the 1st day after injury, and the tissues in the injury area of the two groups were taken for HE staining on the 1st d, 4th d, and 7th d after treatment to observe the tissue morphology; immunohistochemistry was used to detect the expression of myostatin (Mstn), and the images analysis software was used to perform average optical density (AOD) analysis; Western blot was used to detect expression levels of Myod and Mstn protein. Results: In the ESW group, the muscle fiber atrophy was gradually alleviated and the inflammatory cell infiltration was decreased. During this period, a large number of new muscle cells were seen and post-treatment muscle fiber was lined up in order. Results of immunohistochemistry showed that Mstn (1st d: 0.158±0.015, t=3.229, P=0.032; 4th d: 0.203±0.004, t=6.069, P=0.004; 7th d: 0.149±0.009, t=2.821, P=0.048) expression was lower than that in the control group (1st d: 0.190±0.006; 4th d: 0.242±0.189; 7th d: 0.171±0.011). Western blot results showed that the expression of Myod protein in the ESW group was firstly increased with increasing intensity and then decreased (F=50.074, P=0.000). And over time, the amount of expression also showed a trend of rising at first and then falling (F=46.217, P=0.000). With the concentration of 0.14 mJ/mm2, expressions in the treatment group (1st d: 0.998±0.163; 4th d: 1.155±0.059; 7th d: 0.733±0.077) were higher than those in the control group (1st d: 0.410±0.115; 4th d: 0.560±0.194; 7th d: 0.250±0.103). With the increase of the impact strength, the expression of Mstn protein was gradually decreased (F=86.103, P=0.000). Expression at different time was risen at first and then decreased (F=32.380, P=0.000). With the concentration of 0.14 mJ/mm2, expressions in the ESW group (1st d: 0.131±0.044; 4th d: 0.383±0.022; 7th d: 0.162±0.027) were lower than those in the control group (1st d: 0.388±0.060; 4th d: 0.829±0.192; 7th d: 0.508±0.112). Conclusion: This experiment confirms that ESW can promote the repair of skeletal muscle injury in rats.
