The evolution of the denervated gastrocnemii and it's miR-206 and myoD expression during skeletal muscle atrophy in rats / 中华显微外科杂志

ABSTRACT

Objective To investigate the expression pattern of skeletal muscle specific miR-206,myogenesis related myoD which change with time in dcnervated muscle atrophy rats.Methods From June,2015 to January,2016,40 SPF sprague-dawley rats were equally classified into 5 groups randomly according to standard settled before,5 groups were separately defined as denervated 0d group,denervated 1d group,denervated 7d group,denervated 14d group,and denervated 28d group.Each group contained 8 rats.The rats atrophy models were established by cutting sciatic never on left side.According to the different denervated time,the gastrocnemii on both sides were obtained under anesthesia,respectively.The wet weight ratio of two compared gastrocnemii were measured,and the gastrocnemii transection was observed by HE stain,measured the expression of myoD protein by western blot,obtained the expression of miR-206,myoD mRNA by qPCR.Results According to our study on rats denervated atrophy models,the wet ratio of compared gastrocnemius would decrease rapidly,by HE stain,decease of cross sectional area in muscle fiber was observed as well as degeneration.Collagen fibers hyperplasia appeared and increased with time change.Wet ratio and transaction aera ratio of group Od,1d,7d,14d,28d were 0.99±0.04,0.92±0.07,0.68±0.11,0.39±0.06,0.27±0.07 and 0.99±0.02,0.96±0.04,0.51±0.09,0.34±0.08,0.23±０.03 respectively,difference between experimental groups and control group were statistically significant (P＜ 0.05),the differences between each experimental groups were also statistically significant (P＜ 0.05).After qPCR test of miR-206,myoD mRNA expression,it was found that their expression patterns were similar,miR-206,myoD mRNA increased at first and would reach the expression peak at the 7 th day,after that their contents decreased but still higher at the 14th day when compared with that at the 1 st day.Their expression of group 0d,1 d,7d,14d,28d were 0.24±0.06,0.34±0.04,0.68±0.04,0.49± 0.07,0.25±0.03 and 0.41 ±0.06,0.49±0.09,0.93±0.06,0.66±0.03,0.39±0.04,respectively.All experimental groups were statistically significant different when compared with 0d group except 1d group (P＜ 0.05),the differences between each experimental groups were also statistically significant(P＜ 0.05).The protein expression of myoD was also measured by western blot test,which showed nearly the same expression pattern as the mRNA expression pattern.After injury,the protein expression increased and reached the expression peak at the 7th day.The relative expression of myoD of group 0d,1d,7d,14d,28d measured by grey ratio were 1.03±0.05,1.06±0.06,1.42±0.10,0.66±0.13,0.24±0.07,respectively.The difference between experimental groups and control group were statistically significant (P ＜ 0.05),the differences between each experimental groups were statistically significant (P ＜ 0.05) as well.Conclusion The degree of muscle denervation atrophy was related to the denervated duration in rats.The expression regulation of miR-206 and myoD in gastrocnemius was similar during the muscle denervation atrophy,which suggesting having internal relationship between miR-206 and myoD.