Pressing Intervention Promotes the Skeletal Muscle Repair of Traumatic Myofascial Trigger Points in Rats

Objective: To observe the effect of pressing intervention on the skeletal muscle repair of myofascial trigger points (MTrPs) in rats and explore the mechanism of pressing intervention on the deactivation of trigger points. Methods: Thirty SPF rats were randomly divided into blank group, model group and press group, with 10 rats in each group. The MTrPs models were established by blunt striking plus eccentric exercise, and then evaluated. The press group was given a pressing intervention with a self-made device for 14 days, and the rats in the other two groups were fed normally. Soft tissue tension (STT) D0.2 and pressure pain threshold (PPT) were measured before and after intervention. The skeletal muscle tissue at MTrPs was extracted and assessed by hematoxylin-eosin (HE) and Masson staining. The expression of collagen I, collagen III, alpha-smooth muscle actin (alpha-SMA), myosin heavy chain (MHC) and fibronectin (FN) were detected by Western Blotting. Enzyme linked immunosorbent assay (ELISA) was used to evaluate the expression of substance P (SP), 5-hydroxytryptamine (5-HT), cyclooxygenase 2 (COX-2) and prostaglandin E2 (PGE2). Results: (1) Compared with the blank group, the PPT and D0.2 reduced (P < 0.05) in the model group; while compared with the model group, the PPT and D0.2 increased (P < 0.05) in the press group. (2) Compared with the blank group, the model group showed obvious spontaneous potentials with higher amplitude and frequency, which were also much higher than those of the press group (P < 0.05). (3) The HE and Masson staining results showed evident fibrosis in the muscle tissue of the model group, with a larger area of collagen fibers relative to that of the press group (P < 0.05). (4) The amount of collagen I, collagen III, FN, alpha-SMA, SP, 5-HT, COX-2 and PGE2 increased and the content of MHC decreased (P < 0.05) in the model group, as compared to the blank group; while all the substances (P < 0.05), instead of MHC which increased (P < 0.05), in the press group were decreased as compared to the model group. Conclusion: Pressing intervention on the MTrPs in rats can alleviate chronic inflammation, inhibit fibrosis, promote skeletal muscle repair and relieve pain.