甘油诱导的骨骼肌损伤修复过程肌间脂形态学及肌分泌因子表达变化

The Alterations of Intermuscular Fat Accumulation and Myokine Expression during Glycerol-induced Muscle Injury

研究发现在甘油诱导的小鼠肌肉损伤修复过程中可能存在肌间脂的沉积,而肌肉分泌因子(myokines)作为特殊的蛋白参与了肌肉与脂肪的多种生理过程.为研究肌肉内注射甘油后对肌间脂生成的影响,以及注射后肌肉分泌因子在肌肉损伤后修复及肌间脂沉积过程中的表达趋势,本文选用三月龄C57BL/6品系小鼠,右腿胫骨前肌注射50%HBSS(V/V)甘油,左腿胫骨前肌注射等量的HBSS缓冲液作为对照.取注射后不同时期小鼠的胫骨前肌,冰冻切片技术检测肌肉再生及肌间脂沉积状况,实时定量PCR检测各分泌因子(IL-6、IL-15、MSTN、FNDC5、FGF21、myonectin和Insl6)的mRNA表达变化,酶联免疫分析(ELISA)检测分泌因子的蛋白表达变化.结果表明,在甘油诱导的肌肉损伤再生修复过程中存在肌间脂的生成,同时IL-6、Insl6、FGF21和IL-15的mRNA相对表达量在肌肉损伤修复过程中的前、中期变化明显,而MSTN和myonectin的mRNA相对表达量则在中、后期变化明显.IL-6、Insl6的蛋白表达量在前、中期明显升高.综上所述,甘油注射可引起肌肉损伤修复,并在这一过程中伴随着肌间脂的沉积,而肌肉分泌因子作为肌肉与脂肪之间的信息交换因子可能参与了肌肉损伤后的再生修复以及肌间脂的形成.

The accumulation of triacylglycerol and residence of adipocytes within skeletal muscle can be induced by intra-muscular injection of glycerol. Muscle-derived secretory factors（myokines） are specific participating proteins and play a variety of physiological activities in muscle or fat tissues. To determine how myokines were involved in skeletal muscle regeneration and intermuscular fat deposition after injection of glycerol,we used 3-month-old mice of C57 BL/6 background as experimental models. The right leg tibialis anterior（TA） was injected with 50% HBSS（V/V） glycerol; and the left side TA was injected with HBSS only as the control. Mice were sacrificed at indicated time points,and the TA muscles were examined for muscle regeneration and intermuscular fat deposition. The relative mRNA expression levels of myokines（IL-6,IL-15,MSTN,FNDC5,FGF21,myonectin and Insl6） were assayed by real-time PCR.The data showed that the intermuscular fat was developed following glycerol induced muscle injury. The significant difference in the expression of IL-6,Insl6,FGF21 and IL-15 were discovered in early phase during skeletal muscle regeneration; while the MSTN and myonectin expression were significantly different in the middle to late phase. Moreover,the protein concentrations of IL-6 and Insl6 were remarkably increased at middle phase. In conclusion,the deposition of intermuscular fat was accompanied with the muscle regeneration and repair,during which myokines were involved as the crosstalk factors.