内质网应激对Nrf2抗氧化系统调控与高脂诱导的胰岛素抵抗发病机理研究

The Signaling Mechanism of Endoplasmic Reticulum Stress and Its Coupled to Oxidative Stress in Attenuating High Fat Diet Induced Insulin Resistance

目的探讨内质网应激对氧化还原平衡作用及其诱导胰岛素抵抗机制信号机理。方法随机将30只C57BL/6J小鼠分为低脂饲料对照组(LFD组,n=10)和高脂饲料模型组(HFD组,n=20),14周后,经葡萄糖耐量试验(IPGTT)确定胰岛素抵抗模型成功后,HFD组随机选出10只开始进行4-PBA药物干预(HFD+PBA组,n=10),持续1周后检测小鼠葡萄糖耐量(IPGTT)、肌肉和肝脏及相应组织线粒体中丙二醛(MDA)含量;Western blot检测肌肉和肝脏组织中胰岛素信号、内质网应激信号和Nrf2内源性抗氧化系统相关蛋白的表达。结果 4-PBA干预组胰岛素抵抗明显减轻,PTEN蛋白受到抑制从而上调胰岛素信号(PKB Ser473);4-PBA干预组MDA水平明显下降,Nrf2系统信号增强;高脂组Keap1蛋白明显上调,而4-PBA干预则减弱这一变化。结论内质网应激造成氧化应激并通过上调PTEN蛋白和抑制Nrf2抗氧化系统参与胰岛素抵抗。

OBJECTIVE To study the relationship and signaling mechanism between endoplasmic reticulum stress and oxidative stress in the insulin resistance. METHODS 30 C57 BL /6J mice were randomly divided into the low fat diet control group（ LFD,n = 10） and high fat diet modle group（ HFD,n = 10）. After 14 weeks,intraperitoneal glucose tolerance test（ IPGTT） was performed to detect the success of the HFD-induced insulin resistance. Then,10 mice which selected randomly from HFD group were given 4-PBA for 1 week. Then IPGTT,tissue and mitochondrial MDA level were measured; Western blot detect the expression of insulin signaling,endoplasmic reticulum stress signaling and Nrf2 endogenous antioxidant systems in muscle and liver. RESULTS 4-PBA attenuated the high fat diet induced insulin resistance and PKBSer473 phosphorylation was increased with PTEN content reduced; 4-PBA also significantly reduced MDA level,with enhancing the expression of Nrf2; 4-PBA reduced Keap1 content in both tissues of HFD-fed mice. CONCLUSION These data indicate a tight interplay of oxidative stress with ER stress and they both participate the pathogenesis of insulin resistance through upregulating PTEN and downregulating Nrf2 function.