| Objective: Nonalcoholic fatty liver disease(NAFLD) is a pathologically clinical syndrome, sharing much similar characteristics with alcoholic fatty liver disease but without alcohol over-ingestion. In recent years, alone with the development of social economy,there has been an increase in the incidence of NAFLD. So it has become one of the medical and social problems worldwide. Many studies have been done to explore its pathogenesis,but there hasn't been any breakthrough yet. It has been suggested that oxidative stress and lipid peroxidation may play a key role in the development of NAFLD. Thioredoxin is a kind of oxidative stress-induced protein.It is very important to regulate redox equilibrium in the cell.Thioredoxin binding protein-2(TBP-2) is a inhibiting transcription factor of thioredoxin and negatively regulates the expression and the activity of thioredoxin. At present,there is no effective preventative and therapeutic ways and means. In this study, we established rat NAFLD model to probe into the following issues:(1)To observe the role of the expression of TBP-2 mRNA in liver of rats in every stage of NAFLD model.(2)To investigate if traditional Chinese medicine----Jiangzhi Yigan Chongj(iJYC) can treat and prevent NAFLD through regulating the expression of TBP-2 mRNA.This investigation can provide new clues for the pathogenesis of NAFLD and instruct clinical medication.Methods:72 male Wistar rats were randomly divided into 3 groups according to the weight level. Blank control group(BCgroup)were fed standard diet. Experimental control group(ECgroup) were fed with high-fat diet. Experimental intervention group (EIgroup) were given JYC by intragastric administration while fed with high fat diet.Meanwhile each of the three groups were divided into 3 subgroups(9,13 and 17 weeks) respectively:BC1,BC2,BC3,EC1,EC2,EC3,EI1,EI2,EI3.Each subgroup has 8 rats.The group EI1,EI2,EI3were given JYC by intragastric administration separately at 0,9,13 week,meanwhile,the ECand BCgroup were given drinking water in the same way. The rats were put to death separately after 9,13 or 17 weeks. After that the serum, liver homogenate and liver tissue were prepared according to the routine.The following parameters were observed dynamically in each group:body weight,body lenth,liver and spleen weight,at the same time, liver index,Lee's index and the retios of liver and spleen were calculated;the level of aminotransferase,blood fat and lipid in liver tissue were detected by using automatic biochemistry analyzer; fasting blood glucose was detected by glucose oxidase method;serum and liver free fatty acid were detected by copper staining method;serum insulin and tumor necrosis factorαlevel were detected by radio-immunity assay,simultaneously the insulin sensitivity index was calculated; reduced glutathione hormone (GSH), superoxide dismutase (SOD) activity and malondialdehyde (MDA) in serum and liver tissue were measured separately by using colourimetry, xanthinoxidase and thio-barbituric acid;the pathology of liver were observed by hematoxylin and eosin (HE) stain with microscopy; The expression of TBP-2mRNA in rat NAFLD model induced by high fat diet were assayed with reverse transcriptase-polymerase chain reaction (RT-PCR).Results:After 9 weeks, the ECgroup shew to be abdomen-form obesity,developed lipid metabolism disorder accompanied with hyperinsulinemia and insulin resistance, increase of aminotransferase,tumor necrosis fatorα(TNF-α)in serum, malondialdehyde(MDA) in serum and liver and decrease of the vitality of superoxide dismutase , the level of glutathione(GSH) in serum and liver and the expression of TBP-2mRNA in liver, with hepatocyte steatosis shown in hepatic histopathology.Compared with the EC group, the EI group shew improvement of every data,and with statistical difference.After 13 weeks and17 weeks,insulin resistance of the ECgroup showed no significant progress.Compared with BCgroup,the level of aminotransferase, TNF-αin serum,blood fat and liver lipid content were increased greatly in ECgroup,at the same time,the content of malondialdehyde(MDA) increased;the levels of glutathione(GSH), superoxide dismutase, high density lipoprotein cholesterol(HDL-C) in serum and liver were obviously reduced;the expression of TBP-2 mRNA in liver was reduced(P<0.01). Hepatocyte steatosis developed and liver presented the pathology of inflammation cell infiltration and necrosis,the inflammation score in ECgroup were increased significantly compared with BCgroup(P<0.01). Lipid metabolism disorder and insulin resistance of the EIgroup were improved,and the levels of aminotransferase, TNF-αin serum decreased significantly;MDA content decreased;GSH content,SOD activity,HDL-C content in serum and liver increased significantly;the expression of TBP-2 mRNA in liver was decreased compared with the ECgroup(P<0.01);steatosis and inflammation of liver show significant improved compared with the ECgroup.Conclusion:1.Lipid metabolism disorder,insulin resistance, oxidative stress,lipid peroxidation damage and some cytokines such as TNF-αdisorder are well associated with the development of NAFLD.2.The expression of TBP-2 mRNA decreased in the liver of rats with NAFLD,and might reach the lowest point at simple fatty liver. It is demonstrated for the first time that the expression of TBP-2 mRNA in NAFLD model down-regulates.3.JYC can be used to prevent and treat NAFLD of rats and the possible mechanism of action is as follow: (1) JYC increase insulin sensitivity index to improve insulin resistance and decrease significantly the content of TC,TG,LDL-C,FFA and increase the HDL-C content, reduce high blood fat and liver lipid, therefore result in the diminution of lipidoses in liver and alleviation of steatosis and definite anti-inflammatory effect. It reduce the level of ALT,AST in serum to promote the liver function revival.(2) JYC can enhance the activity and content of SOD,GSH,reduce MDA content,lower oxidative stress and lipid peroxidation damage, correct the state of oxidation/anti-oxidation disbalance, obstruct NAFLD development.(3) JYC's molecular mechanism of prevention and treatment may be associated with downregulating the expression of TBP-2 mRNA.(4) JYC can interfere in the genesis and development of NAFLD from multi-angles and multi-targets,and early and long course of treatment may be better to prevent and cure NAFLD,so this traditional Chinese medicine is deserved to generalization. |
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