| Objective:By observing the molecular expression levels of Musk and Rapsyn after sk eletal muscle contusion,to explore the effect and related mechanism of electroacupunct ure at Zusanli and Ashi points on neuromuscular junction reconstruction in the recover y process of acute skeletal muscle contusion in rats.Methods:Fifty-four SD rats were randomly divided into three groups:normal control group(group A),model group(group B)and electroacupuncture group(group C).The n groups A,B and C were divided into three subgroups according to the sampling ti me,with 6 rats in each group.The acute skeletal muscle blunt injury model was esta blished in group B and C by the method of"free fall of heavy objects ".24 hours after the success of the model,group C was given acupoint electrical stimulation of 0.4mA and 2Hz for 15 minutes,and only simulated fixation was performed in group A and group B every other day.At the 7th,28th and 56th day after the establishment of the model,the samples of the three groups were taken at the same time.The mor phological changes of tissue were observed by HE staining,the morphological changes of NMJ were observed by immunofluorescence staining,and the protein and mRNA expression of Musk and Rapsyn were detected by Western-bol and qRT-PCR.Results:HE staining result:The HE staining results showed that the gastrocnemius muscle fib ers of normal rats were arranged neatly and the size of muscle cells was uniform.Se ven days after the establishment of the model,the gastrocnemius muscle fibers in gro up B were dissolved and broken,arranged in disorder and infiltrated by a large numb er of inflammatory cells,while in group C,a small number of newborn muscle cells and muscle fibers were formed and arranged slightly neatly.28 days after the establis hment of the model,the number of newborn muscle cells in group B increased,the n umber of inflammatory cells decreased,and some muscle fibers formed but were still not arranged neatly,The muscle fibers of rats in group C were further increased and arranged neatly.56 days after modeling,the muscle fibers of rats in group B were arr anged neatly and the inflammatory cells decreased significantly.The gastrocnemius mu scle injury of rats in group C basically healed and the morphology and structure were basically intact.Immunofluorescence staining results:After 7 days of injury,the degeneration of NM J was cleaved and dispersed sporadically,and the outline disappeared;With the gradual accumulation of AChR,the area of NMJ increased gradually,and the shape was fuller at 28 days after injury,the number of folds increased and some cracks appeared;At 56 days after injury,the staining morphology of NMJ further increased,and showed a"garland shape" with blurred edges;During the whole recovery process,the shape of NMJ in the electroacupuncture group at each time point was slightly larger than that in the model group.At 56 days after injury,the morphological size of NMJ in the el ectroacupuncture group was basically close to the normal level.Western-blot result:The expression of Musk and Rapsyn protein in normal rat skelet al muscle is low,and injury stimulation can lead to the increase of both protein expre ssion.Compared with group A,the expression of Musk and Rapsyn in group B increas ed significantly on the 7th and 28th day after injury(P<0.05;P<0.05),The expression of Musk and Rapsyn protein reached the peak on the 28th day after injury,then decr eased,and decreased to the normal level on the 56th day after injury(P>0.05).Altho ugh the expression of Musk decreased somewhat,it was still higher than that in grou p A(P<0.05).Compared with group B,the expression level of Musk and Rapsyn pr otein in group C showed the same trend,that is,the expression level increased signifi cantly at 7 days after injury,and the expression peak came at about 28 days after inj ury,and then decreased,but at each time point,the expression level of both proteins in group C was higher than that in group B(P<0.05).RT-PCR result:The mRNA expression of Musk and Rapsyn in skeletal muscle of no rmal rats is low.During the process of natural recovery,the mRNA expression of Mu sk and Rapsyn in skeletal muscle of rats in group B increased significantly on the 7t h day after injury(P<0.05),The mRNA expression of Musk and Rapsyn reached the peak at 28 days after injury,and the expression in group B was still higher than tha t in group A,but there was no significant difference between the two groups,then the expression fell back to close to the normal level on the 56th day.Under the interven tion of electroacupuncture,the mRNA expression of Musk and Rapsyn showed the sa me trend as that of group B,and the expression of mRNA of group C was higher th an that of group B at each time point,but only at 7 days after injury,there was stati stical significance between group C and group B(P<0.05).Conclusion:Electroacupuncture can not only promote the morphological recover of inj ured skeletal muscle,but also accelerate the recruitment of AChR at NMJ by promoti ng the expression of Musk and Rapsyn protein and mRNA,which is beneficial to the morphological and functional recovery of NMJ. |
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