| ObjectTo establish the exercised induced muscle damage experiment model, one bout of downhill running was completed by the rat. The morphological change of the rectus femoris tissue was observed. The activity of serum enzyme was detected. To explore the expression of Myo D and Myogenin in this process. MethodsSeventy-two two months old SD rat was selected as subject. They were divided into nine group, eight per group. Group as follows: a. control group(C); b. 0h after exercise group(T0h); c. 6h after exercise group(T6h); d. 12 h after group(T12h); e. 24 h after exercise group(T24h); f. 48 h after exercise group(T48h); g. 72 h after exercise group(T72h); h. 1week after exercise group(T1w); i. 2 week after group(T2w). Without the control group, the other exercise groups was arranged to one bout of downhill treadmill running. The speed was control at 16m/min, the slope was sat at-16°, and the duration of the exercise was 120 min. The sampling was completed after the given time of exercise to exercise group. While the control group was finished in normal state. All subjects were anesthesia with chloral hydrate(10%) intraperitoneal injection. The blood was obtained through the abdominal aorta, then centrifuged and kept in ultra-low temperature refrigerator. Then the rectus femoris was rapidly separated. All muscle samples were treated with isopentane cooled by liquid nitrogen, then they were placed on dry ice for 20 min, and was kept in ultra-low temperature refrigerator. Following experimental listed:1) Frozen section with HE staining(crosscutting) for the rectus femoris; 2) Colorimetric method and ELISA kits were used to detect the level of serum CK and CK-MM; 3) The expression of Myo D m RNA, myogenin m RNA were detected by RT-PCR 4)The expression of Myo D and Myogenin protein was detected by Western-Blot test. Results 1. HE staining results: The skeletal muscle morphological structure of group C is normal,the muscle fiber showed polygons,size uniformity, packed closely and ruled, and the muscle cell nuclei can be seen in the edge of the muscle cells. Controlled with control group, groups after exercise showed that, muscle fibers with irregularly shaped and scattered exist, other muscle fibers were in swollen State. The cross-section of the group T6 h was found swelling of the muscle fiber. Groups of T12 h and T48 h showed the swelling of the muscle fiber and nuclear clusters aggravated. Group T1 w showed the distribution of muscle fibers restore to normalcy, muscle fibers closely packed, Group T2 w showed the shape of muscle fibers were recovery, packed closely and ruled. 2. Results of serum CK and CK-MM: Through the relevant experimental methods, serum CK immediately was increased from 6h to 48 h after exercise. Compared with group C, group T0 h, T6 h, T72 h and group T1 w showed a statistically significant difference. Serum CK-MM was increased from 0h to 24 h after exercise, then get down to normal. 3. Expression of Myo D m RNA、Myogenin m RNA : Results of the RT-PCR showed, compared with the expression of Myo D m RNA of group C, the expression of Myo D m RNA of group T12 h, group T48 h, group T72 h and Group T1 w showed a statistically significant difference. Compared with the expression of Myogenin m RNA of group C, the expression of Myogenin m RNA of group T12 h, group T24 h, and group T48 h showed a statistically significant difference. 4. Expression of the protein of Myo D and Myogenin: After one bout of downhill running, compared with the result of myogenin protein of the control group, the group T6 h, T12 h was showed a statistically significant difference(P < 0.05), the same is immediately after the exercise began to decline after motion after 24 h group reached the maximum, to decreased to the pre exercise level. After one bout of downhill running, compared with the result of Myo D of the control group, the group T6 h, T12 h and T1 w was showed a statistically significant difference(P < 0.05), the same is immediately after the exercise began to decline after motion after 24 h group reached the maximum, to decreased to the pre exercise level. Conclusion 1. One bout of downhill treadmill running could induce the muscle damage of SD rat, the morphology character of the rat rectus femoris returned to normal state after injury. 2. Combine the change character of serum CK and CK-MM, they could considered as the indicator of the evaluation of injury and recovery process. 3. Phase differences was found in the expression of Myo D and Myogenin m RNA in the exercise induced skeletal muscle damage induced by a single run downhill... |
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