| Objective:(1)To duplicate nonalcoholic fatty liver animal models by high fat diet. (2) To investigate the role of uncoupling protein-2 in the development of nonalcoholic fatty liver diseases. (3) To explore the effect of cordyceps sinensis (CS), glutathione (GSH) on high-fat diet induced NAFLD in experimental rats and its possible molecular mechanisms。Method: Rats were randomly divided into basic diet group (B group), model group (NAFL group), pathologic group (NASH group), cordyceps sinensis group(CS group) and glutathione group(GSH group). The latter three groups were administered with high-fat diet to establish NAFLD animal models. CS group,GSH group were treated with CS and GSH respectively at the 9th week after high fat diet. Rats in NAFL group were killed at the 8th week and all animals were sacrificed at the end of the 18th week. Biochemical,luceferin-luceferinase method,enzyme-linked immunoabsordent assay(ELISA),immunohistochemistry and molecular biological examinations were used to determine the level changes of ALT, AST, triglyceride (TG), free fatty acid (FFA), superoxide dismutase (SOD), glutathione (GSH), malondialdehyde (MDA) , adenosine triphosphate (ATP), tumor necrosis factor alpha (TNFα) in serum and liver tissue as well as uncoupling protein-2(ucp2)expression in tissue both of protein and mRNA.Results: (1)Compared with the B group, serum and liver TG and FFA levels were significantly elevated (P﹤0.05) in NAFL group, while no apparent changes were observed in serum AST,ALT,TNFα and in liver ATP, MDA,SOD,GSH ,TNFα. Diffusive steatosis and lipid diposition was found in liver. Hepatocyte expression of UCP2 and its mRNA was seen in NAFL group. (2) Compared with NAFL group, levels of TG,FFA,AST,ALT,TNFα,MDA in serum and liver tissue were markedly increased, while SOD,GSH and ATP level was markedly dropped in NASH group (P﹤0.05). Severe hepatosteatosis, inflammative necrosis and local fibrigenisis were shown in liver. Tissue expression of TNFα,UCP2 and its mRNA was also dramatically increased (P﹤0.05). (3) In CS group, serum and liver TG,FFA,AST,ALT,TNFα,MDA levels were significantly decreased, while SOD,ATP and GSH levels were significantly increased (P﹤0.05) compared with NASH group. Diffusive steatosis but no inflammation or fibrosis was found in CS group. A lower level TNFαand UCP2 expression was shown in CS group than in NASH group (P﹤0.05). (4) There were no obviously differences in serum TG,FFA,TNFαand liver tissue TG,FFA,ATP between GSH group and NASH group. Levels of serum ALT,AST,MDA were much lower in GSH group than in NASH group and levels of liver SOD,GSH were much higher in GSH group than NASH group (P﹤0.05).Severe steatosis and inflammative necrosis but no fibrogenisis was found in GSH group. A little drop could be seen in TNFαand UCP2 expression compared with NASH group (P﹥0.05).Conclusion: (1) Animal NAFLD models were duplicated successfully. (2) UCP2 was up-regulated in NAFLD rats. It was an initially beneficial adaptation to lipid exposure, but this response may increase the vulnerability of the fatty liver to injure and could become maladaptive in oxidant stress and ATP depletion. (3) CS could inhibit steatohepatitis derived from NAFLD. Its possible mechanism involves modulating UCP2 expression, and thereby, regulating fatty acid metabolism,energy homeostasis and oxidative processes. (4) Glutathione was proved to have highly protective role against ROS and LPO induced injury to hepatocytes. |
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