| Objects:The model of weightlessness was simulated in this study-hindlimb suspension in order to study the phenomenon of skeletal muscle atrophy caused by hindlimb suspension and molecular mechanism of the occurrence; while establishing endurance training model of exercise-induced MyoD, myogenin, MEF2mRNA change in the role of dystrophin.Methods:The experiment use 28 4-week-old male Sprague-Dawley rats, weighing134.02g.They were randomly divided into 4 groups, control group (C, n=7); treadmill group (E group, n =7); suspension group (U, n=7); treadmill suspension group (EU, n=7). Treadmill Group: the first 3 days, adaptive training, half an hour a day, and then 1.2KM/h, gradient of 5 Every Monday to Saturday, a total of six days, an hour a day, breaks at weekend, trained a total of 8 weeks. Weighed once every week. suspension group:without any special treatment for 8 weeks, suspension for the 9,10-week.Treadmill suspension group: programmed by treadmill training group, then suspension for the 9,10-week.After 8-week treadmill training, taking blood tests of blood lactic acid; suspended after 2 weeks, HE for measuring cross-sectional area, Using RT-PCR method for measuring expression of MEF2mRNA, MyoD, myogeninmRNA.Results:1. Compared with the control group, the body weight of treadmill group reduced, there was significant difference in body weight of two groups of rats (P<0.05).2. Hindlimb suspended for 2 weeks, compared with the suspension group, the decrease margin of gastrocnemius muscle wet weight and cross sectional area of treadmill suspension group is smaller than that in suspension group, and there was significant difference (P<0.05).3. After 8 weeks of treadmill training, compared with the control group, the expression of MEF2mRNA, MyoD and myogeninmRNA have risen, and there was significant difference (P<0.05). Conclusions:1. Compared with the control group, the weight, gastrocnemius muscle wet weight and cross-sectional area decrease significantly, indicating hindlimb suspension can cause reduction in body weight, muscle weight and cross-sectional area, suggesting that the model of hindlimb suspension is successful.2. Compared with the suspension group, body weight of treadmill suspension group increases slightly,but the decrease margin of gastrocnemius muscle wet weight and cross sectional area of treadmill suspension group is smaller, indicating treadmill exercise on prevention of muscle atrophy after suspension has some effect.3. After 8 weeks treadmill training, compared with the control group, the expression of gastrocnemius MyoD, myogenin and MEF2mRNA increase, and there was significant difference (P<0.05). After two weeks of hindlimb suspension, the changes of expression of MyoD, myogenin and MEF2mRNA of two groups have also a big difference, the change of expression of MyoD, myogenin and MEF2mRNA of treadmill suspension group is less than suspension group, there was significant difference (P<0.05). And the trend of expression of MyoD and MEF2mRNA is similar, indicating the mechanism of these two factors in the fight against muscle atrophy is coordinated. The change of expression of these three factors before and after suspension also shows that they can be used as the molecular biology of muscle atrophy. |
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