青钱柳对T2D胰岛素抵抗大鼠肝脏氧化应激、炎症反应及FAS/IRS1的影响

Effects of Cyclocarya paliurus on hepatic oxidative stress reaction,inflammation and FAS/IRS1 in rats of type 2 diabetes insulin resisting

目的研究青钱柳叶水提物(Cyclocarya paliurus aqueous extract,CPAE)对2型糖尿病(type 2 diabetes,T2D)胰岛素抵抗大鼠肝脏氧化应激、炎症反应及FAS/IRS1的影响。方法将高脂饲料喂养8周结合链脲佐菌素(streptozotocin,STZ) 30 mg/kg诱导的成模大鼠(空腹血糖>11.1 mmol/L),随机分为模型组,二甲双胍组(0. 3 g/kg),CPAE低、中、高剂量组(0. 25、0. 5、1 g/kg)。连续灌胃4周,给药期间尾静脉取血测大鼠空腹血糖(fasting blood glucose,FBG)。治疗4周后,测空腹胰岛素(fasting insulin,FINS),计算胰岛素抵抗指数(insulin resistance index,HOMAIR)、胰岛素敏感指数(insulin sensitivity index,ISI);检测血清中甘油三脂(total triglyceride,TC)、总胆固醇(total cholesterol,TG)、低密度脂蛋白(low-density lipoprotein,LDL)、高密度脂蛋白(highdensity lipoprotein,HDL)的含量;比色法检测肝脏中过氧化氢酶(catalase,CAT)、超氧化物歧化酶(superoxide dismutase,SOD)、谷胱甘肽过氧化物酶(glutathione peroxidase,GSH-PX)、丙二醛(malondialdehyde,MDA)、游离脂肪酸(free fatty acid,FFA)的含量;放免法测肿瘤坏死因子α(tumor necrosis factor alpha,TNF-α)、白细胞介素1β(interleukin-1β,IL-1β)、白细胞介素6 (interleukin-6,IL-6)的含量;酶免法测脂肪酸合成酶(fatty acid synthase,FAS)、胰岛素受体底物1(insulin receptor substrate 1,IRS1)、磷酸化胰岛素受体底物1(phosphorylated insulin receptor substrate 1,P-IRS1)的含量; RT-qPCR检测肝脏FAS、IRS1 mRNA的表达量。结果与模型组比较:(1) CPAE低、中、高剂量组FPG、HOMA-IR,TC、TG、LDL、HDL显著降低(P<0.05);(2)肝脏CAT、SOD、GSH-PX显著升高(P<0.05),TNFα、IL1β、IL-6,MDA显著降低(P<0.05);(3)肝脏P-IRS1/IRS1蛋白比值和IRS1 mRNA含量显著升高,FAS蛋白表达量及mRNA的含量显著降低(P<0.05)。结论 CPAE提高T2D胰岛素抵抗大鼠肝脏中抗氧化酶的含量,调节氧化应激和炎症反应,缓解胰岛素抵抗,改善T2D大鼠糖脂代谢紊乱,其机制可能与CPAE可提高P-IRS1含量,抑制FAS表达有关。

Objective To study the effects of Cyclocarya paliurus aqueous extract （CPAE） on type 2 diabetes （T2D） insulin resisting hepatic oxidative stress reaction, inflammation and FAS/IRS1 in rat model. Methods The rats with T2D insulin resistance were fed with high-fat diet for 8 weeks. At the 9 th week, streptozotocin （STZ） was injected intraperitoneally into the rat at a dose of 30 mg/kg. The diabetic rats （fasting blood glucose 〉11.1 mmol/L） were randomly divided into model group, metformin group （0.3 g/kg）, CPAE low, medium and high dose group （0.25 g/kg, 0.5 g/kg, 1 g/kg）. During 4 weeks’ continuous gavage, blood in tail vein was collected to measure fasting blood glucose （FBG）. After treatment for 4 weeks, the fasting insulin （FINS） was measured to calculate insulin resistance index （HOMA-IR） and insulin sensitivity index （ISI）, and total cholesterol （TC）, triglyceride （TG）, low-density lipoprotein （LDL） and high density lipoprotein （HDL） level were also measured. The concentration of Catalase （CAT）, superoxide dismutase （SOD）, glutathione peroxidase （GSH-PX）, malondialdehyde （MDA） and free fatty acid （FFA） in liver were measured by Colorimetric method. The tumor necrosis factor alpha （TNFα）, interleukin 1β （IL1β） and interleukin 6 （IL-6） were determined by Radioimmunoassay. The content of hepatic Phosphorylation of insulin receptor substrate 1 （P-IRS1）, insulin receptor substrate 1 （IRS1）, and fatty acid synthase （FAS） were measured by ELISA. RT-qPCR was used to detect the expression amount of hepatic IRS1 and FAS mRNA. Results （1） Compared with the model group, FPG, HOMA-IR, Hepatic FFA, TNFα, IL1β, IL-6 and MDA in the low, middle and high dose groups of CPAE were significantly decreased （ P 〈0.05）; （2） CAT, SOD, GSH-PX in liver increased significantly （ P 〈0.05）; （3） Hepatic P-IRS1/IRS1 and mRNA expression levels increased significantly, and FAS protein and mRNA decreased （ P 〈0.05）. Conclusion CPAE can increase the content of antioxidant enzymes in liver of T2D rats, regulate oxidative stress reaction and inflammation, relieve insulin resistance and improve glucose and lipid metabolism disorders in T2D rats. The mechanism is possibly related to the increase of phosphorylated IRS1 and inhibition of FAS expression.