运动对Keap1/Nrf2信号通路增强糖尿病大鼠心肌抗氧化能力的研究

Effects of exercise on Keap1/Nrf2 signaling pathway enhancing myocardial antioxidant capacity in diabetic rats

目的观察运动对糖尿病大鼠模型心肌氧化应激损伤的改善作用,探讨Keap1/Nrf2信号通路的调节作用。方法将大鼠分为正常对照(NC)组、T2DM组(T2DM)和T2DM运动组(T2DME),T2DM和T2DME组建立T2DM大鼠模型,NC和T2DM组安静饲养8周,T2DME组进行8周的跑台训练。实验结束后测量大鼠体重、心脏重量,检测大鼠血糖。生化法检测心肌丙二醛(MDA)含量、总超氧化物歧化酶(T-SOD)和谷胱甘肽过氧化物酶(GSH-PX)酶活性。RT-PCR和Western blot检测血红素加氧酶1(HO-1)、Kelch样ECH联合蛋白1(Keap1)、核转录因子2(Nrf2)基因和蛋白表达。结果与NC组比较,T2DM组体重降低[(528±71)vs(362±33)g,P<0. 05],心脏重量指数(HWI)、血糖、心肌MDA含量升高[(2. 84±0. 22)vs(3. 84±0. 21),(6. 4±3. 8)vs(26. 0±7. 5)mmol/L,(5. 80±0. 73)vs(9. 51±1. 57)nmol/mg,P<0. 05或P<0. 01],T-SOD、GSH-PX活性,HO-1蛋白表达降低(P<0. 05或P<0. 01),Keap1和Nrf2 mRNA和蛋白无明显变化,Nrf2核转位减少(P<0. 05)。与T2DM组比较,T2DME组体重和心脏重量无明显变化,HWI、血糖、心肌MDA含量降低[(3. 84±0. 21)vs(3. 24±0. 23),(26. 0±7. 5)vs(21. 0±6. 8)mmol/L,(9. 51±1. 57)vs(7. 82±1. 77)nmol/mg,P<0. 05],T-SOD、GSH-PX活性,HO-1基因和蛋白表达升高(P<0. 05或P<0. 01),Keap1通路蛋白无明显变化,Nrf2通路蛋白表达升高(P<0. 05),Nrf2核转位升高(P<0. 01)。结论运动通过激活大鼠心肌Keap1/Nrf2信号通路,促进下游抗氧化酶表达,增加心肌抗氧化能力,抵抗糖尿病诱导的心肌氧化应激损伤。

Objective To investigate the effects of exercise on the myocardial oxidative stress injury in diabetic rats and to explore the regulation of Keap1/Nrf2 signaling pathway in this process.Methods Type 2 diabetic rat model was established by streptozotocin injection through abdominal cavity and high fat diet.The rats were divided into three groups:normal control group(NC),diabetes group(T2DM)and diabetes exercise group(T2DME).NC and T2DM group were routinely housed for 8 weeks.T2DME group was trained treadmill for 8 weeks.At the end of the experiment,the body weight of the rat and its heart weight were weighed.Blood glucose,myocardial malondialdehyde(MDA)content,total superoxide dismutase(T-SOD)and glutathione peroxidase(GSH-PX)enzymatic activity were measured and analyzed.The expressions of heme oxygenase 1(HO-1),Kelch-like ECH associated protein 1(Keap1)and nuclear transcription factor 2(Nrf2)were detected by RT-PCR and Western blot.Results Compared with NC group,the weight of rats in T2DM group[(528±71)vs(362±33)g,P<0.05],the heart weight index(HWI)[(2.84±0.22)vs(3.84±0.21),P<0.05]and blood glucose were higher[(6.4±3.8)vs(26.0±7.5)mmol/L,P<0.01];T-SOD and GSH-PX activity decreased significantly(P<0.05);Ho-1 protein expression in-creased(P<0.01);Keap1 and Nrf2 showed no significant changes;Nrf2 nuclear transposition decreased(P<0.05).Compared with the T2DM group,HWI[(3.84±0.21)vs(3.24±0.23),P<0.05]and blood glucose[(26.0±7.5)vs(21.0±6.8)mmol/L,P<0.05]were higher in T2DME group,with no signifi-cant change in body weight and heart weight.Ho-1 gene and protein expression increased significantly(P<0.05 or P<0.01).There was no significant change in the expression of Keap1.Nrf2 expression and nuclear transposition increased significantly(P<0.05 or P<0.01).Conclusion Exercise promotes the expression of downstream antioxidant enzymes to increase cardiac antioxidant capacity and to resist diabetic myocardial oxidative stress injury in rats by activating the myocardial Keap1/Nrf2 signaling pathway.