| Objective:To study the effect of exhaustive exercise and contusion on satellite cells and Pax7/ CBF1/DAPT in skeletal muscle of rat, and analyze the repair mechanism of skeletal muscle injury.Methods:24 five-weeks-old male SD rats were randomly divided into 4 groups,6 rats in each group:exhaustive exercise group(E,3 groupsx6 rats),control group (C,1 group×6 rats).The rats in exhaustive exercise group do one-time exhaustive exercise on the downhill treadmill until they were exhausted,and were divided into 3groups:instantly exhaustive exercise group (Exhaustive EO), post-exhaustive exercise group 24h (E24), post-exhaustive exercise group 48h (E48).18 five-weeks-old male SD rats were randomly divided into 3 groups, there are 6 rats in each group:contusion immediate group (contusion Do),post-contusion 24h group (D24), post-contusion 48h group (D48).All the groups of rats were narcotized by 20% urethane at their abdominal at different time,and were extracted for serum and right gastrocnemius muscles.Gastrocnemius muscles were divided into 2 parts,one was for cell culture.the other stored in bridge at-80℃.All the serum and gastrocnemius muscles were tested for Pax7、CBF1 and DAPT contents by ELISA. In addition,3 three-days-old male SD rats were slaughtered for cell culture with their right gastrocnemius muscles.Results:(1) The results of satellite muscle cell culture showed that, satellite cells could externally be highly purified with a myogenic ability in vitro by separating the tat skeletal muscle tissue of digestion. During the early stages of culture.the satellite cells of each group were growing slowly except the newborn rats. On the fifth day, each group began to proliferate in quantity and they reached the peak of proliferation on the seventh day.Then the proliferation rate began to decrease. By comparing the results of each group, we concluded that the content of skeletal muscle satellite cell in control group was the lowest and its proliferation rate was slowest, but the content of skeletal satellite cells in newborn rats was highest and the proliferation rate was fastest. Ulteriorly,some differences exists.The number of skeletal satellite cells in contusion groups was significantly larger than the exhaustive exercise groups, and the proliferation rate was also faster than the exhaustive groups. In newborn rats A small number of spindle cells appcred on the second day and proliferated later.Then some satellite cells fused to be myotubule with central cell nucleus.(2) The results of Elisa showed that the contents of Pax7、CBF1 in skeletal muscle in exhaustive groups and contusion groups, compared to the control group, were significantly increased with a apparent difference; P<0.05). The contents of DAPT in skeletal muscle in exhaustive groups and contusion groups, compared to the control group, were significantly decreased also with a apparent difference (P<0.05),while there was no significant difference between exhaustive group and contusion group.Conclusions:(1) According to the satellite muscle cells proliferating condition, control group existed no increased satellite muscle cells,but the proliferating number and speed of muscle satellite cells of 3 three-days-old male rats were at the supreme level,which showed that satellite cells were activated during their growing ages and supporting their metabolism.On the other hand, the proliferating number and speed in exhaustive group and contusion group mediated between control group and 3 three-days-old group. Satellite muscle cells proliferation mightily showed that muscle injury degree of contusion group were more grievous.(2)Exhaustive exercise and contusion increased the contents of Pax7 and CBF1 in skeletal muscle, decreased the contents of DAPT. The Pax7 and CBF1 may play a positive regulating role in terms of activating skeletal satellite cells and repairing of skeletal muscle injury,while DAPT may play a negative regulating role. |
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