电针调控肥胖大鼠肝脏FoxO1及其对脂质代谢的影响

Mechanism of Electroacupuncture Mediated Hepatic FoxO1 in Regulating Lipid Metabolism of Obese Rats

目的：观察电针调控肝脏FoxO1磷酸化及其对肝脏脂质代谢的影响,探讨电针改善肥胖调控脂质代谢的可能机制。方法：将20只高脂饲料诱导的肥胖大鼠和10只普通饲料喂养的大鼠分为正常组（n=10）、模型组（n=10）、电针组（n=10）。正常组给予普通饲料喂养,模型组给予高脂饲料喂养,电针组在高脂饲料喂养的基础上给予电针治疗。取穴为中脘、关元、足三里、丰隆,电针频率2 Hz,强度0.5～1 m A,每周治疗3次,共治疗8周。观察各组大鼠治疗前后的体质量、lee’s指数的变化;观察各组大鼠治疗后的血清TC、TG、VLDL的水平;通过Western Blotting检测各组大鼠肝脏FoxO1、p-FoxO1的蛋白表达水平;通过Realtime-PCR法检测肝脏MTP、Apo CIII的基因表达水平。结果：所有大鼠的体质量均较干预前上升,但电针组的体质量上升幅度小于模型组（P〈0.05）;正常组与模型组的lee’s指数较干预前无明显变化,电针组Lee’s指数较治疗前下降（P〈0.05）,亦明显低于模型组（P〈0.05）。模型组大鼠血清TC、TG、VLDL水平显著高于正常组,电针组TC、TG、VLDL水平低于模型组（P〈0.05）。模型组大鼠的FoxO1和p-FoxO1水平显著低于正常组（P〈0.05）,电针组FoxO1水平高于模型组、低于正常组（P〈0.05）,p-FoxO1水平高于模型组（P〈0.05）,与正常组无显著性差异（P〉0.05）。正常组大鼠的MTP、Apo CIII基因表达水平高于模型组和正常组（P〈0.05）,电针组MTP、Apo CIII基因表达水平高于模型组（P〈0.05）。结论：电针能够上调肝脏FoxO1的蛋白表达,特别是能够明显上调FoxO1的磷酸化水平,FoxO1磷化后从细胞核内转移至胞浆,进而介导下游载脂蛋白MTP、Apo CIII的基因表达水平被下调,VLDL蛋白合成减少,最终导致TC、TG向细胞外的转运减少,VLDL的构建被抑制,达到调控指质代谢的目的。

Objective： To observe the effectiveness of electroacupuncture（ EA） induced hepatic FoxO1 phosphorylation and the regulation in lipid metabolism and discuss the possible mechanism of acupuncture in treating obesity and dyslipidemia. Methods： Twenty high fat induced obese rats and 10 normal rats were divided into normal group（ NG,n = 10）,model group（ MG,n = 10） and EA group（ EG,n = 10）. Rats in NG were fed with normal diet,while those in MG were fed with high fat diet. In addition to fed with high fat diet,rats in EG were treated by EA. EA was applied at the acupoints of Zusanli（ ST36）,Guanyuan（ CV4）,Zhongwan（ CV12） and Fenglong（ ST40）. The acupoints were electrically stimulated with successive waves of 2 Hz. Intensity was adjusted to produce local muscle contractions that varied from 0. 5 to 1 m A. Rats in EG received EA treatment for 10 min every other day for 8 weeks. Body mass and Lee＇s index were obtained before and after EA treatment. The levels of TC,TG and VLDL in serum were detected after treatment. Westernblotting was performed to investigate the protein levels of FoxO1 and p-FoxO1 in hepatic tissue and realtime PCR was conducted to test the gene expressions of hepatic MTP and Apo CIII. Results： Body mass in 3 groups were increased after treatment,but the increase value in EG was lower than that in MG（ P〈 0. 05）. Lee＇s index of NG and MG did not alter after intervention,while those in EG were decreased after treatment. The serum levels of TC,TG and VLDL in MG were significantly higher than that in NG,while those in EG were lower than those in MG（ P〈 0. 05）. The protein expressions of FoxO1 and p-FoxO1 were significantly lower than that in NG. FoxO1 in EG was higher than that in MG and lower than that in NG,while p-FoxO1 in EG was higher than that in MG and had no difference compared with NG. The gene expressions of MTP and Apo CIII in NG were higher than that in MG and EG,while those in EA were higher than that in MG. Conclusion： EA can up-regulate the expression of FoxO1 protein in the liver,in particular,can significantly increase the phosphorylation of FoxO1. EA induced FoxO1 phosphorylation led the transfer from nucleus to the cytoplasm,which mediated gene expression levels of downstream apolipoprotein MTP. Apo CIII was down-regulated and protein synthesis was decreased. Eventually,the extracellular transportation of TC and TG were reduced and VLDL construction was inhibited,which controlling the lipid metabolism.