| Objective:Apoptosis is a capacity of a cell to undergo programmed death? it goes through in the whole life of multi-cellular organism,such as growth,development and disease.In order to close the mechanism of exercise-induced skeletal muscle micro-injury,this study investigated the sequential change of three days repeated eccentric exercise on the skeletal muscle Damage,Apoptosis and Proliferation in rats.Methods:50 male SD rats aged at 8 weeks old randomly divided into control group(A) and training group,the training group was divided into four groups by B1(post-exercise o hour),B2(3 hours),B3(24 hours),B4(48 hours),and every group has 10 rats. the training group run for exhaust on a treadmill every day. which the speed was 16metre/mintues,grade was-16°.After have repeated training for three days,Rats were sentenced to death respectively.The blood routines were assayed and 1.5ml of blood taken to be made into serum.Serum CK,serum LDH and serum SOD were determined,and forelimb medial head of triceps branchiis were fetched for electron-microscope and made into paraffin wax sample.The change of the skeletal muscle cells' ultra-micro - structure and satellite cell proliferation and differentiation were observed through electron microscope(TEM).The skeletal cell structure was detected in Paraffin sections by HE normal regulations dyeing.Apoptosis was detected in paraffin sections by the TUNEL technique. Immuno-histochemical and computer image processing technique were applied to detect positive expression and quantificational analysis for PCNA and vimentin.Results:(l) The shape structure and ultra-micro-structure had changed follow the change of time within different range after three days repeated eccentric exercise? and the Abnormal rate of Ultra-micro-structure and the Abnormal rate of Z line and damage degree has gradually increased with the time course.the most severe change occurred post-exercise 24 hours and it has seldom restoration at post-exercise 48 hours.The activities of serum creatine kinase(CK) and lactate dehy drogenase(LDH) increased significantly after three days repeated eccentric exercise,and the occurrence time of peak serum CK level was post-exercise 24 hours,and LDH activity emerges double-phase changes? the occurrence time of peak were post-exercise 0 hours and 24 hours.SOD activity decreased significantly in post-exercise 0 hour,and then increased gradually.(2) The index of apoptosis increased significantly after exercise.And it reached peak in 24 hours post-exercise.(3) PCNA protein express increased significantly after exercise,it also presents double-phase changes,At post-exercise 0 hours,it increased quickly,and the myoblast and muscle fusion can be seen under the electron microscope.At post-exercise 3 hours,the index of proliferation is reduced(P<0.05),it reached the peak in post-exercise 24 hours, and it has seldom restoration in post-exercise 48 hours.(4) Different range positive dye of anti vimentin antibody had took place,which this change was most obvious in post-exercise 24-48 hours.But the peak of average optical density(OD) is in post-exercise 0 hour.And with the time course change,the OD decreased.Conclusion:(1) Three days repeated eccentric exercise can induce delayed micro-injuries of skeletal muscle.CK can better reflect the skeletal muscle damage than LDH. (2) The skeletal muscle cells apoptosis present sequential changes after three days repeated eccentric exercise.The skeletal muscle cells apoptosis may induced the recurrent skeletal muscle damage.(3) The satellite cells proliferation present sequential changes after three days repeated eccentric exercise,this research demonstrated correlativity between skeletal muscle cell apoptosis and proliferation.The apoptosis maybe a start factor for proliferation.(4) The express of vimentin present sequential changes, and apoptosis,proliferation and the express of vimentin have the same trend of sequential changes.This research demonstrated no correlation between the vitmentin and cell proliferation.
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