耐力运动结合雷帕霉素对高脂膳食大鼠骨骼肌能量代谢相关基因表达的影响

Effects of Exercise Combined with Chronic Rapamycin on mRNA Expression of Protein Involved in Energy Metabolism in Rats Fed a High–fat Diet

目的:探讨哺乳动物雷帕霉素靶蛋白(mechanistic target of rapamycin,m TOR)抑制剂雷帕霉素结合耐力运动对高脂膳食大鼠骨骼肌线粒体氧化酶及能量代谢相关转录因子基因表达的影响。方法:选用喂养高脂膳食6周的SPF级雄性SD大鼠,随机分成4组(每组6只):高脂膳食+安静对照组(H组)、高脂膳食+运动组(HE组)、高脂膳食+雷帕霉素组(HR组)、高脂膳食+运动+雷帕霉素组(HER组)。所有大鼠适应性训练1周后,运动大鼠进行4周耐力递增负荷跑台训练(第8~11周);雷帕霉素给药大鼠第10~11周每日腹腔注射雷帕霉素(剂量为2 mg/kg体重/日)。实验结束检测大鼠糖耐量、胰岛素耐量,以及骨骼肌线粒体氧化酶活性和能量代谢相关转录因子的基因表达。结果:HER组大鼠体重、体脂百分比和血浆瘦素水平均低于H组(P<0.05)。糖耐量试验中HE组的糖耐量曲线下面积小于其余三组(P<0.05),HR和HER二组的曲线下面积大于H组(P<0.05);胰岛素耐量试验中HE组的胰岛素耐量曲线下面积比其他三组小(P<0.05)。HR组和HER组比目鱼肌琥珀酸脱氢酶活性均低于H组和HE组(P<0.05),而运动对趾长伸肌细胞色素氧化酶活性有主效应(P<0.05)。进一步分析骨骼肌能量代谢相关转录因子的基因表达结果显示,HER组趾长伸肌过氧化物酶体增殖物激活体辅激活因子1α(peroxisome proliferater-activated receptor gamma coactivator 1α,PGC-1α) mRNA含量高于H组和HE组(P<0.05),而HR组和HER组比目鱼肌过氧化物酶增殖体激活受体β(peroxisome proliferator-activated receptorsβ,PPARβ) mRNA含量低于H组(P<0.05)。结论:雷帕霉素影响高脂膳食大鼠运动时骨骼肌线粒体氧化酶及能量代谢相关基因表达,但具有肌纤维特异性。

Objective To investigate the effect of rapamycin,an inhibitor of mechanistic target of rapamycin(mTOR),combined with exercise on the expression of mitochondrial oxidase and energy metabolism related genes in skeletal muscle of high-fat diet(HFD) rats. Method Totally 24 male SPF rats were fed HFD for 6 weeks,then randomly divided into an HFD + sedentary group(H group),an HFD + exercise group(HE group),an HFD + rapamycin(HR group) and an HFD + exercise + rapamycin group(HER group),each of 6. After one week of adaptive training,the rats of HE and HER groups were trained on treadmill at an increasing speed for 4 weeks(from the 8 th to 11 th weeks),while those of HR and HER groups received the intraperitoneal injection of rapamycin with the dose of 2 mg/kg/day for 2 weeks(from the 10 th to 11 th weeks). At the end of the experiment,the glucose tolerance and insulin tolerance tests were performed,and soleus(SOL) and extensor digitorum longus(EDL) were harvested to analyze the activity of the mitochondria oxidative enzyme and gene expression involved in energy metabolism. Result The body weight,body fat percentage and plasma leptin level of HER group were significantly lower than those of H group(P<0.05). Moreover,in the glucose tolerance test,the area under curve of HE group was significantly lower than that of the other 3 groups(P<0.05),while that of HR and HER groups were significantly higher than that of H group(P<0.05).In the insulin tolerance test,the area under curve of HE group was significantly lower than that of H,HR and HER groups(P<0.05). Analysis on activity of mitochondrial oxidase in the skeletal muscle showed that SOL succinodehydrogenase activities of HR and HER groups were significantly lower than H and HE groups(P<0.05) and exercise had the main effect on the cytochrome oxidase activity in EDL of HFD rats(P<0.05). Moreover,the analysis on energy metabolism related genes expression in the skeletal muscle showed that the peroxisome proliferater-activated receptor gamma coactivator 1αmRNA content of EDL of HER group was significantly higher than that of H and HE groups(P<0.05),while the peroxisome proliferator-activated receptors β mRNA content of SOL of HR and HER groups were significantly lower than that of H group(P<0.05). Conclusion The rapamycin regulates the exercise-induced expression of mitochondrial oxidase and energy metabolism related genes in the skeletal muscle of high-fat diet rats in a muscle fiber specific manner.