The Study Of Change Of Macrophages In Rat Skeletal Muscle After Eccentric Exercise

Objective: Macrophages are an important component of the body’s naturalimmune system,and play a variety of immune function in vivo,includingphagocytosis of bacteria, viruses and other microorganisms,and antigenpresenting and processing.In recent years, studies have found thatmacrophage not only have phagocytosis’s role, but also to promotesatellite cell proliferation, differentiation, migration and integration,to play an important role in muscle repair.This study was designed by thedownhill running injury model induced skeletal muscle injury, theninvestigated the variance of serum Mb; the situation of the injury andrepaired soleus muscle,and the variance of macrophages expressed ininjured skeletal muscle（soleus muscle） by immunochemistry, and providedexperimental bases for the role of macrophages in repair of injuredskeletal muscle.Methods: Male SD rats(n=72,8weeks of age) were divided into controlgroup(C,n=8) and exercise group(E,n=64), the exercise group thensub-divided into0h group,6h group,12h group,1d group,2d group,3d group,1w group,2w group(n=8) by avoirdupois. Exercise groups rats had to dodownhill running of90minutes,which the speed was16metre/minutes, gradewas-16°. Then rats were killed after pentobarbital administration,Inferior vena cava blood was collected for detecting by ELISA;the ratswere rapidly dissected respectively at0h、6h、12h、1d、2d、3d、1w and2w later,then soleus were fetched for HE staining andimmunohistochemistry staining. The pictures were taken and analyzed byusing Olympus DX70microscope and Image-Pro Plus4.1software. The datawas analyzed by using SPSS18.0statistical software.Results:(1) Analysis: serum Mb content of the12h post-exercise hassignificant differences compared with the control group, and theexperimental and control groups showed no significant change in serum Mb(P>0.05).(2) HE staining: C group of gastrocnemius and soleus cell inrats with order, rules, no abnormity; from0h to1d, the muscle cellsgradually began to swell,and were round approximately. There were nucleargrowing and gathered in local. And gradually at6h, inflammatory cellsbegan to infiltrate, particularly in the perivascular tissue, reached thepeak at3d group. which shows the injury was most serious at this time.But There’re inflammatory cells at1w and2w in soleus.(3)immunohistochemical analysis:Mb positive expression was brown or tanparticles, located in muscle cytoplasm. M1and M2macrophages’s expressionin each experimental group have the following rules:in the3d after theinjury, the expression of M1macrophages was significantly higher thanthat of M2macrophages,in the3d~2w after injury, the expression of M2macrophages was significantly higher than the M1macrophages;expressionlevels of M1and M2macrophages macrophages in3d reached a peak afterthe injury;M2macrophages in the process of muscle damage and repairalways exist, and M2macrophages have not detected. in C、0h group.Conclusion:(1)Disposable downhill running exercise can lead to micro-ratsoleus muscle damage.(2) After a one-time downhill run,the expression of M1and M2macrophagesboth rose and showed certain variation in the soleus muscle injury andrepair;in the3d after the injury, the expression of M1macrophages wassignificantly higher than that of M2macrophages,in the3d~2w after injury,the expression of M2macrophages was significantly higher than the M1macrophages;and M1macrophages and the expression of M2macrophages havereached a peak in the3d.