摘要目的:探讨二甲双胍对高脂培养肌细胞自噬的作用及可能机制。方法:用不同浓度棕榈酸(0.1、0.2、0.4、0.6 mmol/L)及二甲双胍(0.5、1、2、5、10 mmol/L)分别干预L6肌细胞24 h，CCK 8法检测肌细胞的存活率。棕榈酸和二甲双胍干预肌细胞24 h后，Western印迹检测微管相关轻链蛋白3(LC3Ⅱ)、自噬相关蛋白Beclin 1、泛素结合蛋白p62、沉默信息调节因子2相关酶3(SIRT3)蛋白表达及腺苷酸活化的蛋白激酶(AMPK)磷酸化水平，RT-PCR技术检测上述基因的mRNA表达水平。结果:棕榈酸剂量依赖性地降低肌细胞活力，2 mmol/L二甲双胍显示最佳的对抗作用。0.4 mmol/L棕榈酸和2 mmol/L二甲双胍干预肌细胞24 h后，棕榈酸显著减少LC3Ⅱ/LC3I、Beclin 1、SIRT3的蛋白及mRNA表达水平，降低AMPK磷酸化水平，显著增加p62的蛋白及mRNA表达水平(均 P<0.05)，棕榈酸的这些作用可被二甲双胍所对抗(均 P<0.05)。 结论:二甲双胍可能通过刺激AMPK的磷酸化增加SIRT3的表达而增强脂肪酸培养的肌细胞自噬。

abstractsObjective:To investigate the effect of metformin on autophagy in muscle cells exposed to palmitic acid, and to explore its mechanism.Methods:L6 rat myoblasts were incubated with palmitic acid at various concentrations(0.1, 0.2, 0.4, 0.6 mmol/L) and metformin(0.5, 1, 2, 5, 10 mmol/L) for 24 h. CCK8 method was used to detect the survival rate of muscle cells. After muscle cells were treated with palmitic acid and metformin for 24 h, mRNA and protein expressions of microtubule-associated protein11ight chain3(LC3Ⅱ), Beclin 1, p62, and silent mating type information regulation2 homolog-3(SIRT3) were detected by RT-PCR and Western blot, respectively. AMP-activated protein kinase(AMPK) phosphorylation level was detected by Western blot.Results:Palmitic acid dose-dependently decreased the survival rate of muscle cells, which was attenuated by metformin at the concentration of 2 mmol/L. After muscle cells were incubated with 0.4 mmol/L palmitic acid and 2 mmol/L metformin for 24 h, palmitic acid significantly reduced the mRNA and protein expressions of LC3Ⅱ, Beclin1, and SIRT3 as well as phosphorylation level of AMPK(all P<0.05), and increased p62 mRNA and protein expressions( P<0.05). Those effects were all antagonized by metformin(all P<0.05). Conclusions:Metformin treatment may promote the autophagy of muscle cells exposed to palmitic acid through AMPK/STRT3 pathway.