The Study Of Change Of TNF-α In Rat Skeletal Muscle Injury And Repair

Objective TNF-a as an important starting of antibacterial key cytokines of inflammatory response, has been considered as a negative regulatory factor in the study of chronic myopathy. But in recent years, research found that TNF-a can play the role of physiological regulation in the early stages of myogenic differentiation of the repair of acute injured skeletal muscle. This study was designed by the downhill running injury model induced skeletal muscle injury, then investigated the variance of serum TNF-a; the situation of the injury and repaired gastrocnemius and soleus muscle, and the variance of TNF-a expressed in injured skeletal muscle (gastrocnemius and soleus muscle) by immunochemistry, and provided experimental bases for the role of TNF-α in repair of injured skeletal muscle.Methods:Male SD rats(n=72,8weeks of age) were divided into control group(C,n=8) and exercise group(E, n=64), the exercise group then sub-divided into Oh group,6h group,12h group,Id group,2d group,3d group, lw group,2w group(n=8) by avoirdupois. Exercise groups rats had to do downhill running of90minutes,which the speed was16metre/mintues, grade was-16°. Then rats were killed after pentobarbital administration, Inferior vena cava blood was collected for detecting by ELISA;the rats were rapidly dissected respectively at Oh,6h,12h,1d,2d,3d,lw and2w later, then gastrocnemius and soleus were fetched for HE staining and immunohistochemistry staining. The pictures were taken and analyzed by using Olympus DX70microscope and Image-Pro Plus4.1software. The data was analyzed by using SPSS17.0statistical software.Results:(1) Analysis:serum TNF-a content were less in the control and experimental groups, and the experimental and control groups showed no significant change in serum TNF-a (P>0.05).(2) HE staining:C group of gastrocnemius and soleus cell in rats with order, rules, no abnormity; from Oh to Id, the muscle cells gradually began to swell,and were round approximately. There were nuclear growing and gathered in local. And gradually at6h, inflammatory cells began to infiltrate, particularly in the perivascular tissue, reached the peak at3d group, which shows the injury was most serious at this time. In gastrocnemius, there’s occasionally inflammatory cell infiltrating at lw group; the morphology of the muscle fibers restored to normal and saw new myofibes at2w group. But there’re inflammatory cells at lw and2w in soleus, and there was no new myogenic fiber at2w.(3) immunohistochemical analysis:TNF-α positive expression was brown or tan particles, located in muscle membrane and cytoplasm, staining between the junction of cells was deeper.We saw a small amount of positive expression of TNF-a in the cytoplasm of muscle fibers at control group (C) both gastrocnemius and soleus muscles. Expression of TNF-α in all experimental groups (gastrocnemius and soleus muscle) were significantly higher than C group(P<0.01); Especially the expression of TNF-a increased significantly after exercise instantly,(P<0.01).In the soleus muscle, expression peak of TNF-a was at Oh group (P<0.01). But in the gastrocnemius, TNF-a appeared expression peak respectively in the Oh and3d group.Conclusion:(1) One-time downhill running exercise induced damage of rat skeletal muscle:soleus were more significant and longer for repairing than gastrocnemius.(2) After one-time downhill running exercise, injury and repair of the two types of muscle fiber types, TNF-expression of a whole were elevated, and showed certain variation. It clewed TNF-a may have a certain role to skeletal muscle injury and repair.