Effect of electrical stimulation combined with diet therapy on insulin resistance via mTOR signaling.

Insulin resistance (IR) is the impaired insulin response that causes decreased glucose tolerance. Electrical stimulation (ES) can improve insulin sensitivity in the skeletal muscle. However, the underlying molecular mechanisms remain to be elucidated. In the present study, the effect of ES and diet therapy on IR and the role of the mammalian target of rapamycin (mTOR) pathway in the improvement of IR by ES were investigated. A total of 70 Sprague­Dawley male rats were divided into five groups: Normal (n=10), IR control (n=15), diet (n=15), ES (n=15) and ES + diet (n=15) groups. An IR rat model was established by high­fat and high­carbohydrate diet for 5 weeks and confirmed by measurement of fasting plasma glucose (FPG), insulin, insulin sensitivity index (ISI) and IR index. ES on the Zusanli (ST36), Sanyinjiao (SP 6) and Weiwanxiashu (EX­B3) acupoints and the low­fat and low­carbohydrate diet demonstrated protective effects. The body weight, concentrations of FPG, insulin, triglycerides (TG), free fatty acids (FFA) and total cholesterol (TC) of the rats were detected. Pathologic changes in the liver and pancreatic tissues were assessed. Western blotting and immunohistochemistry were performed to determine the role of PI3K/Akt/mTOR signaling. Results demonstrated that ES and diet therapy significantly increased ISI and reduced FPG, IR index, FFA, TG, TC and weight. Inflammatory cell infiltration in the liver and pancreatic tissues was ameliorated and lipid droplets and cavitation in hepatocyte were decreased after ES and diet therapy. The administration of ES and diet therapy also enhanced glucose transport by the upregulation of glucose transporter 4 and accelerated glycogen synthesis through the suppression of glycogen synthase kinase 3α/ß via PI3K/Akt/mTOR signaling. Hence, the present results demonstrated that ES combined with diet therapy improved IR through PI3K/Akt/mTOR signaling. The proposed therapy was superior to the method of diet alone.

[Effect of Electroacupunctrue on ERp57 in NAFLD Rats].

OBJECTIVE: To investigate the effect of electroacupunctrue on ERp57 in non-alcoholic fatty liver disease (NAFLD) rats, and study the therapeutic mechanism of electroacupunctrue in patients with NAFLD. METHODS: Sixty male SD rats were randomly divided into common diet group (n = 15) and high-fat diet group (n = 45). 5 weeks later, two rats from the two groups were executed and confirmed that the model was successful. Then 10 rats in common diet group were chosen as control group (Control), and 40 rats in high-fat diet group were randomly chosen and divided into diet group 1 (D1), diet group 2 (D2), electroacupuncture group 1 (EA) and electroacupuncture group 2 (EA2) (n = 10 each). D1 and EA1 were fed by high fat diet; D2 and EA2 were fed with common diet. In EA1 and EA2, filiform needle acupuncture was applied to ST36, SP6 and Liv3 and electroacupunctrue was applied to one-side of ST36, SP6 for 20 min once daily for 4 weeks. The rats in each group were weighed per-week. After the treatment the changes of blood lipid and liver functions of these rats were observed. ERp57 gene expression and protein expression were detected by RT-PCR and Western blot, and expression of ERp57 downstream SREBP-1c was detected. RESULTS: The body mass of D1 increased slowly and were lower than D2 and EA1 (P < 0.05); the body weights of EA2 increased rapidly and were higher than EA1 (P < 0.05), but without significant difference with D2 (P > 0.05). The contents of blood lipid, liver functions and the expression of ERp57 and SREBP-1c were significantly higher than those in Control, D2 and EA1 (P < 0.05). While compared to D2 and EA1 respectively, the index mentioned above in EA2 decreased more significantly (P < 0.05). CONCLUSION: Electroacupunctrue can decrease expression of ERp57 to improve endoplasmic reticulum stress (ERS) of rats with NAFLD and then decrease expression of SREBP-1c to regulate rat lipid, which could be one of mechanism to cure NAFLD.

[Effects of Electroacupunctrue Combined with Dietary Control on Peroxisome Proliferator-activa- ted Receptor-α, and Liver Fatty Acid-binding Protein Levels in Non-alcoholic Fatty Liver Disease Rats].

OBJECTIVE: To observe the effect of electroacupunctrue (EA) intervention or EA combined with dietary control on peroxisome proliferator-activated receptor (PPAR)-α, and liver fatty acid-binding protein (L-FABP) levels in non-alcoholic fatty liver disease (NAFLD) rats, so as to reveal its mechanism underlying improvement of NAFLD. METHODS: Sixty SD male rats were randomly divided into common diet (control) group (n = 10) and high-fat diet group (n = 45). The NAFLD model was established by feeding the animals with high-fat forage (HFF, including cholesterol, sodium cholate, propylthiouracil, sucrose, lard and common forage) for 5 weeks. Forty NAFLD rats were then randomized into model, EA + HFF, low-fat forage (LFF) and EA+ LFF groups (n = 10 rats in each group). EA (4 Hz/20 Hz, 3 mA) was applied to ipsilateral "Zusanli" (ST 36),"Sanyinjiao" (SP 6) and "Taichong" (LR 3) for 20 min, once daily for 4 weeks. The pathologic changes of the hepatic tissue were detected by H. E. staining. Serum total cholesterol (TC) and triglyceride (TG) contents were determined by using enzymatic methods, serum free fat acids (FFA) content was detected by colorimetry. The expression levels of PPAR-α and L-FABP protein and gene of the liver tissue were determined by Western blot and RT-PCR, respectively. RESULTS: H. E. staining showed that the hepatocytes presented moderate or severe bullous adipose degeneration in rats of the model group, vesicular steatosis in the EA + HFF and LFF groups, turned to almost normal but with small amount of lipid droplets in the EA + LFF group. The contents of serum TC, TG and FFA were significantly higher in the model group than in the control group (P < 0.05), and were obviously decreased in the EA + HFF, LFF and EA + LFF groups in comparison with the model group (P < 0.05). Compared to the control group, hepatic PPAR-α protein and mRNA were markedly down-regulated in the model group, and hepatic L-FABP protein and mRNA considerably up-regulated in the model group (P < 0.05). Following EA intervention and low fat diet feeding, PPAR-α protein and mRNA were markedly up-regulated while L-FABP protein and mRNA remarkably down-regulated in the EA + HFF, LFF and EA + LFF groups (P < 0.05). CONCLUSION: EA intervention or EA combined with dietary control can relieve hepatic pathological changes in NAFLD rats, which may be related to its effects in down-regulating blood lipid level and hepatic L-FABP protein and mRNA expression and in up-regulating PPAR-α protein and mRNA expression, and the effect of combined treatment was relatively better than simple EA or LFF treatment.

[Effect of electro-acupuncture on hepatic Toll-like receptor 4 and nuclear factor κB expressions in rats with non-alcoholic fatty liver disease].

OBJECTIVE: To investigate the effect of electro-acupuncture on Toll-like receptor 4 (TLR4) nuclear factor κB (NF-κB) expressions in the liver of rats with non-alcoholic fatty liver disease (NAFLD). METHODS: SD rat models of NAFLD induced by feeding high-fat diet for 5 weeks were subjected to early or late intervention with electro-acupuncture at the acupoints Zusanli, Fenglong and Sanyinjiao for 20 min once daily for 21 consecutive days. The changes in serum ALT, AST, TC, and TG levels were determined in the rats and hepatic expressions of TLR4 and NF-κB detected with quantitative fluorescence PCR and Western blotting after treatments. RESULTS: Serum ALT, AST, TC, and TG levels and TLR4 and NF-κB levels increased significantly after NAFLD onset (P<0.05), and were markedly reduced by interventions with electro-acupuncture (P<0.05). CONCLUSION: Electro-acupuncture at the acupoints Zusanli, Fenglong and Sanyinjiao can modify blood lipid and hepatic function to produce positive effect on NAFLD possibly by modifying lipid metabolism, lowering expressions of TLR4 and NF-κB in the liver, and reducing the impact of inflammation on NAFLD.