薯蓣皂苷通过调控SIRT1-FoxO1-自噬通路减轻糖尿病大鼠胰岛素抵抗

目的:探究薯蓣皂苷是否通过调控沉默信息调节因子1(sirtuin 1,SIRT1)-叉头框蛋白O1(forkhead box protein O1,FoxO1)-自噬通路减轻糖尿病大鼠胰岛素抵抗。方法:将60只SPF级SD大鼠随机分为对照组、模型组、低剂量(5 mg/kg)薯蓣皂苷组、中剂量(10 mg/kg)薯蓣皂苷组、高剂量(20 mg/kg)薯蓣皂苷组和薯蓣皂苷(20 mg/kg)+EX-527(SIRT1抑制剂)组,每组10只。高脂饲料喂养4周后腹腔注射链脲佐菌素以构建2型糖尿病(type 2 diabetes mellitus,T2DM)大鼠模型,低、中、高剂量薯蓣皂苷组和薯蓣皂苷+EX-527组大鼠分别灌胃相应剂量药物,对照组和模型组大鼠灌胃等量生理盐水,每天1次,为期4周。全自动生化分析仪检测血清中空腹血糖(fasting blood glucose,FBG)、高密度脂蛋白胆固醇(high-density lipoprotein cholesterol,HDL-C)、低密度脂蛋白胆固醇(low-density lipoprotein cholesterol,LDL-C)、甘油三酯(triglyceride,TG)和总胆固醇(total cholesterol,TC)水平,酶联免疫吸附实验检测血清空腹胰岛素(fasting insulin,FINS)水平,计算胰岛素抵抗指数(homeostasis model assessment-insulin resistance,HOMA-IR)和胰岛素敏感指数(insulin sensitivity index,ISI),行口服葡萄糖耐量实验(oral glucose tolerance test,OGTT),计算OGTT曲线下区域面积(area under curve,AUC);HE染色观察大鼠胰腺组织损伤情况;使用Western blot检测胰腺组织中beclin-1、LC3及SIRT1-FoxO1自噬通路相关蛋白的表达。结果:与对照组相比,模型组FBG、AUC、FINS、HOMA-IR、体重、TG、TC和LDL-C水平、胰腺组织损伤程度及FoxO1水平显著增加,ISI、beclin-1、LC3-II/LC3-I和SIRT1水平显著降低(P<0.05);与模型组相比,低、中、高剂量组FBG、AUC、FINS、HOMA-IR、体重、TG、TC和LDL-C水平、胰腺组织损伤程度及FoxO1水平以薯蓣皂苷剂量依赖性的方式显著降低,ISI、beclin-1、LC3-II/LC3-I和SIRT1水平以薯蓣皂苷剂量依赖性的方式显著增加(P<0.05);与高剂量薯蓣皂苷组相比,薯蓣皂苷+EX-527组FBG、AUC、FINS、HOMA-IR、体重、TG、TC和LDL-C水平、胰腺组织损伤程度及FoxO1水平显著增加,ISI、beclin-1、LC3-II/LC3-I和SIRT1水平显著降低(P<0.05)。结论:薯蓣皂苷可能通过激活SIRT1-FoxO1-自噬通路减轻T2DM大鼠胰岛素抵抗。

Dioscin attenuates insulin resistance in diabetic rats by regulating SIRT1-FoxO1-autophagy signaling pathway

AIM:To explore whether dioscin regulates sirtuin 1(SIRT1)-forkhead box protein O1(FoxO1)-autophagy signaling pathway to attenuate insulin resistance in diabetic rats.METHODS:Sixty SPF SD rats were randomly divided into control group,model group,low-dose(5 mg/kg)dioscin group,medium-dose(10 mg/kg)dioscin group,high-dose(20 mg/kg)dioscin group and dioscin(20 mg/kg)+EX-527(SIRT1 inhibitor)group,with 10 mice in each group. Streptozotocin was injected intraperitoneally after feeding with high-fat diet for 4 weeks to establish a rat model of type 2 diabetes mellitus(T2 DM). The rats in low-,medium-and high-dose dioscin groups and dioscin+EX-527 group were given the corresponding doses of drugs by gavage,while those in control group and model group were given the same volume of normal saline by gavage,once daily for 4 weeks. The automatic biochemical analyzer was used to detect fasting blood glucose(FBG),high-density lipoprotein cholesterol(HDL-C),low-density lipoprotein cholesterol(LDL-C),triglyceride(TG)and total cholesterol(TC)levels. ELISA was used to detect the serum fasting insulin(FINS)level and calculate homeostasis model assessment-insulin resistance(HOMA-IR)and insulin sensitivity index(ISI). Oral glucose tolerance test(OGTT)was performed to calculate the area under curve(AUC)of the OGTT. HE staining was used to observe the damage of rat pancreatic tissues. Western blot was used to detect the expression of beclin-1,LC3 and SIRT1-FoxO1-autophagy pathway related-proteins in pancreatic tissues.RESULTS:Compared with control group,the FBG,AUC,FINS,HOMA-IR,body weight,TG,TC and LDL-C levels,the pancreatic tissue damage,and the FoxO1 level increased significantly,while the ISI,beclin-1,LC3-II/LC3-I and SIRT1 levels reduced significantly in model group(P<0. 05). Compared with model group,the FBG,AUC,FINS,HOMA-IR,body weight,TG,TC and LDL-C levels,the pancreatic tissue damage,and the FoxO1 level reduced significantly,while the ISI,beclin-1,LC3 II/LC3-I and SIRT1 levels increased significantly in low-,medium-and high-dose dioscin groups in a dose-dependent manner(P<0. 05).Compared with high-dose dioscin group,the FBG,AUC,FINS,HOMA-IR,body weight,TG,TC and LDL-C levels,the pancreatic tissue damage,and the FoxO1 level increased significantly,while the ISI,beclin-1,LC3-II/LC3-I and SIRT1 levels reduced significantly in dioscin+EX-527 group(P<0. 05).CONCLUSION:Dioscin may attenuate the insulin resistance of T2 DM rats by activating the SIRT1-FoxO1-autophagy signaling pathway.