Effects of different strength of pressing massage on myofascial trigger points with chronic pain in rats / 中国组织工程研究

ABSTRACT

BACKGROUND:Pressing massage applied to myofascial trigger points(MTrPs)has shown clear effect in relieving pain.However,further research is needed to investigate the effects of different levels of pressure applied during the massage. OBJECTIVE:To investigate the different strength of pressing on MTrPs in rats with chronic pain. METHODS:Sixty SPF-rated male Sprague-Dawley rats were randomly divided into a blank group of 10 rats not involved in MTrPs modeling and 50 rats involved in modeling.The MTrPs model was established in the left medial thigh muscle of rats by blunt strikes combined with centrifugal exercise and 40 rats that met the evaluation criteria after modeling were randomly divided into model group,light press group,medium press group and heavy press group,with 10 rats in each group.The rats in the blank group and the model group were not intervened,while the rats in the light press group,the medium press group and the heavy press group were intervened with a homemade press stimulator with light force(0.3 kg),medium force(0.5 kg)and heavy force(0.7 kg)to MTrPs.The intervention time was 7.5 minutes per session,with one session every other day,totaling seven sessions.Electromyogram,soft tissue tension and mechanical pain threshold were detected by electrophysiological instruments,soft tissue tension tester,and pressure painmeter,respectively.After the intervention,in the blank group,muscle tissue was taken from the inside of the left thigh,while in the other groups,MTrPs tissue was taken.The pathological morphology was observed by hematoxylin-eosin staining,while enzyme-linked immunosorbent assay(ELISA)was used to detect the levels of cyclooxygenase-2,prostaglandin E2 and bradykinin. RESULTS AND CONCLUSION:Compared with the blank group,the model group had lower mechanical pain thresholds,higher soft tissue tone,higher amplitude frequency of spontaneous electrical activity,significant pathomorphological changes,and increased levels of cyclooxygenase-2,prostaglandin E2 and bradykinin(P<0.05).Compared with the model group,the medium press group and the heavy press group showed increased mechanical pain thresholds,decreased soft tissue tension,decreased spontaneous potential frequency amplitude,and decreased levels of cyclooxygenase-2,prostaglandin E2 and bradykinin(P<0.05),and significant recovery on pathomorphological changes.No significant changes in the above indicators were observed in the light press group(P>0.05).Compared with the medium press group,the heavy press group showed better improvement in the above indicators(P<0.05).To conclude,moderate to heavy pressing is often required to alleviate MTrPs pain.