| Objective Exercise-Induced Damage has been one of the hot and fundamental issues in the field of sports medicine for many years, some mechanism of regeneration and myogenesis in the process of repair of skeletal muscle is still unclear. It has been proved presently that all mammals'skeletal muscle has the capacity to repair and regeneration,satellite cells is the only source of the repairing function after damage. Fibroblast growth factor6 (FGF6) belongs to a family of cytokines that control cell proliferation, cell differentiation, and morphogenetic events,and FGF6 exhibits a restricted expression profile predominantly in the myogenic lineage. Important functions of FGF6 in wound healing and tissue regeneration have been proposed. This study aims to observe observation the changes of FGF6 expression in gastrocnemius after a 90min downhill exercise through animal experiments, and further reveal the mechanism of the regeneration after damage induced by exercise, and finally provide new experimental evidence for improving the muscle regeneration theory,and provide a new thinking and method for muscle injury, muscle degenerative diseases, gene diagnosis and treatment.MethodsMale SD rats (n=64, 8 weeks of age) were used in the experiments. The rats were housed in a temperature (22±2℃) and humidity (60±5%)-controlled room regulated to provide alternating 12-h periods of light and darkness. They were allowed to feed and drink ad libitum.Afer adapt training they were divided into control group(C,n=8)and exercise group(E,n=56)which were then sub-divided into 6h,12h,24h,48h,72h,1w and 2w group(n=8)by avoirdupois. Exercise group rats had to do downhill running for 90min,the speed was 16m/min and the gradient was-16°.Then rats were killed after pentobarbital administration, and gastrocnemius were rapidly dissected respectively at 6h,12h,24h,48h,72h,1w and 2w later,and were rendered to the following analysis: observe the structure and changes of gastrocnemius by HE staining,detect FGF6 mRNA expression expression RT-PCR and detect the change of FGF6 protein expression by immunohistochemical.Results(1) histological analysis:the gastrocnemius cells in the control group were polygonal nest distribution, the size is normal, muscle nuclear distributed in muscle plasma membrane surrounding, did not see the swelling,muscle membrane integrity, clearance is clear;12h~72h group observed swelling increase gradually, inflammatory cells within the nucleus accelerated, a small slice muscle fiber dissolving phenomenon;1wAn occasional inflammatory cells infiltrating reduce muscle fiber structure, normalizes;2w The basic normal muscle fiber morphological structure.(2) FGF6 mRNA:after One-time downhill run,the expression of FGF6 mRNA in the excise group rats were increased except 1w group, compared with control group, 6h,24h,and 48h group rats FGF6 mRNA were significantly increased(P<0.05).(3) immunohistochemical analysis :FGF6 positive reaction was brown or tan particles,located in muscle membrane and cytoplasm, staining between the junction of cells was deeper. Excise group rats FGF6 Immune positive express area and Integrated Optical Density decline after briefly rising.6h~12h group FGF6 Immune positive express area and Integrated Optical Density increased(P<0.05);afer 24h FGF6 declined,48h~2w group FGF6 significantly declined(P<0.05).Conclusion(1)One-time downhill run excise could induce skeletal muscle damage,after2 weeks skeletal muscle damage repaird.(2)After one-time downhill run excise,FGF6 expression of gastrocnemius increased , after 24h declined.
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