Mibefradil可改善肥胖小鼠骨骼肌的质量、功能和结构

目的 探讨mibefradil对肥胖小鼠骨骼肌质量、功能及结构的影响。方法 将15只6周龄C57BL/6小鼠随机分为普通饮食组（Con组，n=5）、高脂饮食组（HFD组，n=5）和高脂饮食+mibefradil干预组（HFD+Mibe组，n=5）。电子抓力仪测量小鼠前肢抓力，DXA分析小鼠后肢肌肉含量，GPO-PAP法测定甘油三酯和总胆固醇，HE染色观察小鼠腓肠肌肌纤维横截面积，Westernblot和免疫荧光技术检测自噬水平变化，Western blot检测Akt/mTOR信号通路的激活情况。结果 与Con组相比，HFD组体质量增加，相对抓力、后肢肌肉比率降低（P<0.05），给予mibefradil干预后体质量减轻，相对抓力升高、后肢肌肉比率升高（P< 0.05）；HE染色结果显示，与Con组相比，HFD组平均肌纤维横截面积降低，给予mibefradil干预后平均肌纤维横截面积得到改善（P<0.05）；免疫荧光结果显示，HFD组和HFD+Mibe组的LC3多均匀分布于细胞浆，呈浅淡红色荧光；而在HFD组检测到不同程度的明亮斑点状红色荧光；Western blot结果显示，与Con组相比，HFD组LC3Ⅱ蛋白表达水平升高，P62蛋白表达水平降低，AKT和mTOR的磷酸化表达降低，给予mibefradil干预后LC3Ⅱ蛋白表达水平降低，P62蛋白表达水平升高，AKT和mTOR的磷酸化表达升高（P<0.05）。结论 给予mibefradil干预可以抵抗高脂诱导的体质量增加，改善肥胖小鼠的肌肉质量和功能，这可能与其改善脂代谢和通过激活AKT/mTOR信号通路来抑制肥胖诱导的过度自噬有关。

Mibefradil improves skeletal muscle mass,function and structure in obese mice

Objective To observe the effect of mibefradil on skeletal muscle mass, function and structure in obese mice. Methods Fifteen 6-week-old C57BL/6 mice were randomized equally into normal diet group (control group), high-fat diet (HFD) group and high-fat diet +mibefradil intervention group (HFD +Mibe group). The grip strength of the mice was measured using an electronic grip strength meter, and the muscle content of the hindlimb was analyzed by X-ray absorptiometry (DXA). Triglyceride (TG) and total cholesterol (TC) levels of the mice were measured with GPO-PAP method. The cross-sectional area of the muscle fibers was observed with HE staining. The changes in the level of autophagy in the muscles were detected by Western blotting and immunofluorescence assay, and the activation of the Akt/mTOR signaling pathway was detected with Western blotting. Results Compared with those in the control group, the mice in HFD group had a significantly greater body weight, lower relative grip strength, smaller average cross sectional area of the muscle fibers, and a lower hindlimb muscle ratio (P<0.05). Immunofluorescence assay revealed a homogenous distribution of LC3 emitting light red fluorescence in the cytoplasm in the muscle cells in HFD group and HFD +Mibe group, while bright spots of red fluorescence were detected in HFD group. In HFD group, the muscular tissues of the mice showed an increased expression level of LC3 II protein with lowered expressions of p62 protein and phosphorylated AKT and mTOR (P<0.05). Mibefradil treatment significantly reduced body weight of the mice, lowered the expression level of p62 protein, and increased forelimb grip strength, hindlimb muscle ratio, cross-sectional area of the muscle fibers, and the expression levels of LC3 II protein and phosphorylated AKT and mTOR (P<0.05). Conclusion Mibefradil treatment can moderate high-fat diet-induced weight gain and improve muscle mass and function in obese mice possibly by activating AKT/mTOR signal pathway to improve lipid metabolism and inhibit obesity-induced autophagy.