二十碳五烯酸通过p38 MAPK通路对肥胖大鼠骨骼肌胰岛素抵抗的作用研究

Effect of eicosapentaenoic acid on skeletal muscle insulin resistance of obesity rats by inhibiting the p38 MAPK pathway

目的探讨二十碳五烯酸(EPA)通过调控p38丝裂原活化蛋白激酶(p38 MAPK)信号通路对肥胖大鼠骨骼肌胰岛素抵抗的改善作用。方法将50只雄性Wistar大鼠随机分组为对照组、模型组、抑制剂组、EPA组、抑制剂+EPA组,每组10只,共干预6周。造模后抑制剂组灌胃1 mg/kg p38 MAPK抑制剂SB203580,EPA组灌胃70 mg/kg EPA,抑制剂+EPA组灌胃SB203580+EPA,模型组和对照组灌胃等体积生理盐水。测定大鼠空腹血糖、空腹血清胰岛素水平、骨骼肌组织中谷胱甘肽过氧化物酶(GSH-Px)、超氧化物歧化酶(SOD)活性和丙二醛(MDA)水平,采用腹腔葡萄糖耐量实验(IPGTT)和胰岛素耐受实验(ITT)评价大鼠胰岛素抵抗程度,采用Western blot法和实时荧光定量PCR(qRT-PCR)法测定大鼠骨骼肌组织中磷酸化p38(p-p38)蛋白及p38 mRNA表达情况。结果与对照组相比,模型组大鼠体重、附睾脂肪湿重、空腹血糖、空腹胰岛素水平、IPGTT血糖水平、ITT血糖水平、MDA水平明显升高,GSH-Px和SOD活性明显降低,骨骼肌组织中p-p38蛋白表达和p38 mRNA表达明显升高(P<0.05)。与模型组相比,EPA组和抑制剂+EPA组大鼠的体重和附睾脂肪湿重明显降低,抑制剂组和EPA组大鼠空腹血糖、空腹胰岛素水平、IPGTT血糖水平、ITT血糖水平、MDA水平明显降低,GSH-Px和SOD活性明显升高,骨骼肌组织中p-p38蛋白表达明显降低(P<0.05),但骨骼肌组织中p38 mRNA表达无明显改变(P>0.05)。结论EPA可能是通过抑制p38 MAPK信号通路减轻氧化应激反应,从而改善肥胖大鼠骨骼肌胰岛素抵抗。

Objective To explore the improving effect of eicosapentaenoic acid(EPA)on the skeletal muscle insulin resistance in obese rats by regulating the p38 MAPK signaling pathway.Methods Fifty male Wistar rats were randomly divided into the control group,model group,inhibitor group,EPA group and inhibitor+EPA group,10 cases in each group.The intervention lasted for 6 weeks.The inhibitor group was given 1 mg/kg p38 MAPK inhibitor SB203580 by gavage.The EPA group was given 70 mg/kg EPA by gavage,the inhibitor+EPA group was given SB203580+EPA by gavage,and the model group and control group were given equal volume of saline.The levels of fasting blood-glucose,fasting serum insulin,glutathione peroxidase(GSH-Px),superoxide dismutase(SOD)and malondialdehyde(MDA)in the skeletal muscles were determined.The rat insulin resistance degree was evaluated by using the intraperitoneal glucose tolerance test(IPGTT)and insulin tolerance test(ITT).The protein and mRNA expression levels of phosphorylation p38 in the rat skeletal muscle tissues were detected by Western blot and qRT-PCR.Results Compared with the control group,the body weight,epididymal fat wet weight,fasting blood-glucose and insulin levels,IPGTT and ITT blood glucose levels,and MDA content in the model group were significantly increased,the GSH-Px and SOD activities were significantly decreased,and the relative expression levels of p-p38 protein and p38 mRNA expression in skeletal muscle tissues were significantly increased(P<0.05).Compared with the model group,the body weight and epididymal fat wet weight in the EPA group and inhibitor+EPA group were significantly decreased,while the fasting blood-glucose,fasting serum insulin,IPGTT and ITT blood glucose levels and MDA contents in the inhibitor group and EPA group were significantly decreased,the activities of GSH-Px and SOD were significantly increased,and the relative expression level of p-p38 protein in skeletal muscle tissues was significantly decreased(P<0.05).However,the expression of p38 mRNA in skeletal muscle tissues had no significant change(P>0.05).Conclusion EPA alleviates the oxidative stress possibly by inhibiting p38 MAPK signaling pathway,thus improves the skeletal muscle insulin resistance of obese rats.