α-硫辛酸通过激活AMPK/mTOR通路改善2型糖尿病大鼠肝脏病变

α-lipoic acid ameliorates liver injury in rats with type 2 diabetes mellitus via activating AMPK/mTOR pathway

目的:探讨α-硫辛酸是否通过激活腺苷酸活化蛋白激酶(AMPK)/雷帕霉素靶蛋白(mTOR)通路改善2型糖尿病(T2DM)大鼠肝损伤。方法:应用高糖高脂饮食联合链脲佐菌素27.5 mg/(kg·d)腹腔注射法制备T2DM大鼠模型。将32只成模大鼠随机分为4组:T2DM组、α-硫辛酸组、Compound C(AMPK抑制剂)组和α-硫辛酸+Compound C组,每组各8只。另8只健康Sprague-Dawlay(SD)大鼠作为正常对照组。α-硫辛酸注射液100 mg/(kg·d)腹腔注射,Compound C 20 mg/(kg·d)腹腔注射,药物干预共持续8周。检测相关生化指标;计算肝脏质量指数;进行光镜、电镜观察;采用Western blot方法检测大鼠肝脏中AMPK、p-AMPK、mTOR、p-mTOR蛋白的表达水平。结果:与正常对照组相比,T2DM组大鼠肝脏质量指数、胰岛素抵抗指数、空腹血糖、谷丙转氨酶、谷草转氨酶、γ–谷氨酰转肽酶、甘油三酯水平均升高(P均<0.05);肝组织结构损伤,脂肪变明显;肝脏组织中p-AMPK表达显著减少(P<0.05),p-mTOR表达显著增多(P<0.05)。α-硫辛酸可逆转上述改变,改善大鼠的胰岛素抵抗(P<0.05),保护肝脏的结构和功能,同时激活肝细胞内的AMPK/mTOR通路(P均<0.05)。应用Compound C抑制AMPK活性后,α-硫辛酸的上述保护作用受到抑制(P<0.05)。结论:α-硫辛酸可通过激活AMPK/mTOR信号通路发挥对T2DM大鼠的肝脏保护作用。

Objective:To investigate the effect ofα-lipoic acid in ameliorating liver injury in rats with type 2 diabetes mellitus via activating adenosine 5’-monophosphate-activate protein kinase(AMPK)/mammalian target of rapamycin(mTOR)pathway.Methods:The T2DM rat models were established by feeding with high-fat,high-sucrose diet and intraperitoneal injection of 27.5 mg/(kg·d)streptozotocin.The 32 rats with T2DM were randomly divided into 4 groups:T2DM group,α-lipoic acid group(LA),Compound C group(Comp C,an inhibitor of AMPK)and LA+Comp C group,with 8 rats in each group.Additionally,8 Sprague-Dawlay(SD)rats without diabetes were set as normal control.The rats receivedα-lipoic acid at a dosage of 100 mg/(kg·d)or Compound C at a dosage of 20 mg/(kg·d)by intraperitoneal injection for 8 weeks as needed.The levels of relevant biochemical indexes were detected.The weight of liver was recorded to calculate liver weight index(LWI),and the pathological changes of liver tissues were detected by light and electron microscopy.The levels of AMPK,p-AMPK,mTOR,p-mTOR in rat liver were detected by Western blot.Results:Compared with control group,the levels of LWI,homeostasis model assessment of insulin resistance,fasting blood glucose,alanine transaminase,aspartate transaminase,gamma glutamyl transferase and triglyceride in T2DM group were increased significantly(all P<0.05).The liver tissue lesions were more serious and hepatic steatosis grade was higher.The expression of p-AMPK was decreased(P<0.05)and the expression of p-mTOR was increased significantly(P<0.05).α-lipoic acid could reverse the above-mentioned changes,ameliorate insulin resistance(all P<0.05),protect the structure and function of liver,and activate the AMPK/mTOR pathway(P<0.05).The protection ofα-lipoic acid was weakened by the inhibition of AMPK with Compound C(P<0.05).Conclusion:α-lipoic acid could protect the liver of rats with T2DM by activating AMPK/mTOR pathway.