Mechanism of electroacupuncture for regulation of lipid production and improvement in obesity by mediating Wnt/ β-catenin pathway through activating SIRT1

Abstract

To explore the mechanism of electroacupuncture (EA) for the regulation of lipid production and improvement in obesity by mediating Wnt/β-catenin pathway through activating silent information regulator 1 (SIRT1). Of 75 Wistar male rats, 10 rats were selected randomly as the normal group and fed with standard diet. The rest rats were fed with high-fat diet for 8 weeks to establish the obesity model. Forty rats of successful modeling were randomized into a model group, an EA group, an EA plus inhibitor group (EA+I group) and an agonist group, 10 rats in each one. In the EA group, EA was applied at "Guanyuan" (CV 4), "Zhongwan" (CV 12), "Zusanli" (ST 36) and "Fenglong" (ST 40), with continuous wave, 2 Hz in frequency and around 1 mA in intensity. The needles were retained for 20 min. In the EA+I group, sirtinol solution was injected from caudal vein and EA was exerted simultaneously. In the agonist group, resveratrol solution was given by intragastric administration. The intervention of the above three groups was given once every two days, 3 times a week, consecutively for 8 weeks. Before and after intervention, body mass and Lee's index were recorded in the rats of each group. After intervention, the levels of serum total cholesterol (TC), triglyceride (TG) and free fatty acid (FFA) were detected in the rats of each group. After intervention, the mass of white adipose tissue (WAT) and the area of adipocytes were compared in the rats among the 5 groups. Using Western blot method, the protein expressions of SIRT1, glycogen synthase kinase-3β (GSK3β), β-catenin, cyclin D1 and peroxisome proliferators-activated receptor γ (PPARγ) were detected in WAT in the rats of each group. After intervention, compared with the model group, the body mass and Lee's index were reduced in the rats of the EA group and the agonist group (P<0.01, P<0.05), the body mass was reduced in the rats of the EA+I group (P<0.05). Compared with the normal group, the levels of serum TC, TG and FFA, as well as WAT mass were increased in the rats of the model group (P<0.01), as well as the area of adipocytes (P<0.01). Compared with the model group, the levels of serum TC and TG (except in the EA+I group), the levels of FFA and WAT mass were all decreased (P<0.01, P<0.05) and the area of adipocytes was reduced (P<0.01, P<0.05) in the EA group, the agonist group and the EA+I group. Compared with the EA group, the area of adipocytes was increased in the EA+I group (P<0.05). Compared with the normal group, the protein expressions of SIRT1, β-catenin and cyclin D1 in WAT were down-regulated (P<0.01) and the protein expressions of GSK3β and PPARγ in WAT were up-regulated (P<0.01) in the model group. Compared with the model group, the protein expressions of SIRT1, β-catenin and cyclin D1 in WAT were up-regulated (P<0.05, P<0.01) and the expressions of GSK3β and PPARγ in WAT were down-regulated (P<0.01, P<0.05) in the EA group and the agonist group, and in the EA+I group, GSK3β protein expression was down-regulated andβ-catenin protein expression was up-regulated (P<0.05). Electroacupuncture remarkably improves the body mass, Lee's index and blood lipid metabolism and reduces WAT mass and adipocyte size in obesity model rats, which is probably related to up-regulating the protein expression of SIRT1 in WAT, activating Wnt/β-catenin pathway and inhibiting the expression of PPARγ of downstream lipogenic gene so as to affect lipid production.