Objective: To observe the effect of electroacupuncture (EA) on liver protein kinase B (Akt)/forkhead box transcription factor 1 (FoxO1) signaling pathway in Zucker diabetic fatty (ZDF) rats, and to explore the possible mechanism of EA on improving liver insulin resistance of type 2 diabetes mellitus.
Methods: Twelve male 2-month-old ZDF rats were fed with high-fat diet for 4 weeks to establish diabetes model. After modeling, the rats were randomly divided into a model group and an EA group, with 6 rats in each group. In addition, six male Zucker lean (ZL) rats were used as the blank group. The rats in the EA group were treated with EA at bilateral "Zusanli" (ST 36), "Sanyinjiao" (SP 6), "Weiwanxiashu" (EX-B 3), and "Pishu" (BL 20). The ipsilateral "Zusanli" (ST 36) and "Weiwanxiashu" (EX-B 3) were connected to EA device, continuous wave, frequency of 15 Hz, 20 min each time, once a day, six times a week, for a total of 4 weeks. The fasting blood glucose (FBG) in each group was compared before modeling, before intervention and after intervention; the serum levels of insulin (INS) and C-peptide were measured by radioimmunoassay method, and the insulin resistance index (HOMA-IR) was calculated; HE staining method was used to observe the liver tissue morphology; Western blot method was used to detect the protein expression of Akt, FoxO1 and phosphoenolpyruvate carboxykinase (PEPCK) in the liver.
Results: Before intervention, compared with the blank group, FBG was increased in the model group and the EA group (P<0.01); after intervention, compared with the model group, FBG in the EA group was decreased (P<0.01). Compared with the blank group, the serum levels of INS and C-peptide, HOMA-IR, and the protein expression of hepatic FoxO1 and PEPCK were increased (P<0.01), while the protein expression of hepatic Akt was decreased (P<0.01) in the model group. Compared with the model group, the serum levels of INS and C-peptide, HOMA-IR, and the protein expression of hepatic FoxO1 and PEPCK were decreased (P<0.01), while the protein expression of hepatic Akt was increased (P<0.01) in the EA group. In the model group, the hepatocytes were structurally disordered and randomly arranged, with a large number of lipid vacuoles in the cytoplasm. In the EA group, the morphology of hepatocytes tended to be normal and lipid vacuoles were decreased.
Conclusion: EA could reduce FBG and HOMA-IR in ZDF rats, improve liver insulin resistance, which may be related to regulating Akt/FoxO1 signaling pathway.
目的：观察电针对Zucker糖尿病肥胖（ZDF）大鼠肝脏蛋白激酶B（Akt）/叉头框转录因子1（FoxO1）信号通路的影响，探讨电针改善2型糖尿病肝脏胰岛素抵抗的可能机制。方法：12只雄性2月龄ZDF大鼠以高脂饲料喂养4周制备糖尿病模型，成模后随机分为模型组与电针组，每组6只；6只雄性Zucker瘦型（ZL）大鼠作为空白组。电针组大鼠予电针双侧“足三里”“三阴交”“胃脘下俞”“脾俞”干预，同侧“足三里”“胃脘下俞”连接电针，连续波，频率15 Hz，每次20 min，每日1次，每周6次，共干预4周。比较各组大鼠造模前及干预前后空腹血糖（FBG）水平；采用放射免疫法检测各组大鼠血清胰岛素（INS）、C肽含量，并计算胰岛素抵抗指数（HOMA-IR）；HE染色法观察各组大鼠肝脏组织形态；Western blot法检测各组大鼠肝脏Akt、FoxO1、磷酸烯醇式丙酮酸羧激酶（PEPCK）蛋白表达。结果：干预前，与空白组比较，模型组、电针组大鼠FBG升高（P<0.01）；干预后，与模型组比较，电针组大鼠FBG降低（P<0.01）。与空白组比较，模型组大鼠血清INS和C肽含量、HOMA-IR、肝脏FoxO1和PEPCK蛋白表达升高（P<0.01），肝脏Akt蛋白表达降低（P<0.01）；与模型组比较，电针组大鼠血清INS和C肽含量、HOMA-IR、肝脏FoxO1和PEPCK蛋白表达降低（P<0.01），肝脏Akt蛋白表达升高（P<0.01）。模型组大鼠肝细胞结构紊乱，排列散乱，细胞质内出现大量脂质空泡；电针组大鼠肝细胞形态趋于正常，脂质空泡减少。结论：电针能够下调ZDF大鼠空腹血糖、胰岛素抵抗指数，改善肝脏胰岛素抵抗，可能与调控Akt/FoxO1信号通路有关。.
Keywords: electroacupuncture; forkhead box transcription factor 1 (FoxO1); insulin resistance; phosphoenolpyruvate carboxykinase (PEPCK); protein kinase B (Akt); type 2 diabetes mellitus.