Radial extracorporeal shock wave reduces myogenic contracture and muscle atrophy via inhibiting NF-κB/HIF-1α signaling pathway in rabbit

We investigate the underlying biological effects and mechanisms of rESWT on myogenic contracture and muscle atrophy in a rabbit model of extending knee joint contracture.In group control, the knee joint was not fixed. In group I-4w, the knee joint was only fixed for 4 weeks. In groups SR-1 w, SR-2 w, and SR-4 w, the knee joint was fixed for 4 weeks before the rabbits underwent 1, 2, and 4 weeks of self-recovery, respectively. In groups rESWT-1 w, rESWT 2 w, and rESWT-4 w, the knee joint was fixed for 4 weeks before the rabbits underwent 1, 2, and 4 weeks of rESWT, respectively. The myogenic contracture was measured, the cross-sectional area and key protein levels for NF-κB/HIF-1α signaling pathway and myogenic regulatory factors were evaluated.During the recovery period, biological findings showed that the levels of myogenic contracture and muscle atrophy were milder in group rESWT by compared with group SR after 2 weeks. Molecular biological analysis showed that MyoD protein levels in the group rESWT was significantly higher than those in the group SR, and importantly, phospho-NF-κB p65 and HIF-1α protein levels in the group rESWT were significantly lower than those in the group SR at the same time point.This is the first study demonstrated that rESWT has the potential to reduce myogenic contracture and muscle atrophy after long-term immobilization in animal model. It is a possible mechanism that changing the low oxygen environment in skeletal muscle through rESWT may inhibit activation of NF-κB/HIF-1α signaling pathway.