The Study Of The IR And PPARα/γ Expression In NASH

Nonalcoholic fatty liver disease(NAFLD) is a clinicopathological syndrome commonly resulted from heredity,environment,metabolism and stress. Cases of fatty liver disease with inflammation that resembled alcoholic steatohepatitis but occurring in nondrinkers were definited nonalcoholic steatohepatitis(NASH). About three percent of NAFLD are estimated to meet current diagnostic criteria for nonalcoholic steatohepatitis (NASH). Sustaining liver injury leads to progressive fibrosis, cirrhosis, hepatic failure and even heaptocellular carcinoma of those with NASH in a fraction, possibly up to twenty-five percent. However, there is no widely accepted approach to treating NASH at present. It has been suggested that Insulin Resistance(IR) may be an important factor in the pathogenesis of NASH,which is closely related to the disorder of lipidic metabolism and accumulation of hepatocellular, then is reduced to lipid peroxidation and inflammation after its water fall effect. So IR becomes the hot spot to study, prevention and treatment of nonalcoholic fatty liver disease.Present reasarch suggests that peroxisome proliferator-activated receptors (PPARS) plays an important role in improving the insulin resistance. PPARs is a ligand-activated transcription factor that belongs to the superfamily of nuclear hormone receptor subfamily consisting of three members:PPAR-a,PPAR-β,PPAR-γ. PPARa controls expression of genes implicated in lipid metabolism and inflammatory reaction in the liver. As the cross way of many signal transduction pathway, PPARa plays a pivotal role in the cascade reaction of lipid deposit inflammatory mediators release hepatocyte injuried, and its low expression act as a key factor in the pathogensis of NASH. Fenofibrate, the PPARa agonists, which is currently used in the therapy of hyperlipidemia, might also be useful for treating patients with NAFLD. PPARy agonists, such as thiazolidinediones (TZDs) act principally on adipocytes to facilitate their differentiation and enhance their storage capacity for triglycerides, thereby effectively "syphoning fat" out of the liver into subcutaneous deposits, as well as improving insulin sensitivity. There is intense interest in the role of transcription factors in the pathogenesis of NASH, particularly PPARa and PPARy, but in view of the fact that two type acceptor excited medicinal preparation display function's spot is different, it produces the effect also has the difference. How to find two kinds of effects the balance points by a better service in clinical is the core question which the present will study.Therefore NASH rat model with insulin resistance was established by high fat diet and then interfere in fenofibrate and TZDs to investigate their effection of improving IR and steatohepatitis.This study explore the role of PPARS in the pathogensis of NASH, and provide potential way for preventing and treating patients with NASH.ObjectiveTo experimently investigate the role of peroxisome proliferators activated receptors (PPARs) in NAFLD/NASH of SD rats and to explore some evidences the mechanisms in insulin resistance by way of PPARs, especially PPARa and PPARy; and to provide for preventing and treating NAFLD/ NASH by using activable of PPARa and/or PPARy.Methods1 Animal modelSprague Dawley rats were normal control group, ordinary diet feed with protein, fat and carbohydrates providing energy 21%,19%,60% respectively; model group, Feeding high fat diet with protein, fat and carbohydrates providing energy 21%,59%,20% respectively, free eating and drinking.2 Designs experiment60 male SD rats were randomly divided into:1. NC group (n=20) normal chow-fed controls; 2. FR group (n=10) high fat-fed with rosiglitazone group; 3. FF group (n=10) high fat-fed with fenofibrate group; 5. FC group (n=20) high fat-fed control group; At the end of 12th week,10 rats which were randomly selectde form NC group and the 10 rats of FC group were put into glucose clamp test,with liver tissue HE staining and to determine if model success. Give rosiglitazone, fenofibrate and continue high-fat diet intervention, It was a total of four weeks.3 The changes of body weight:From electronic balance that weight.4 Determination of insulin sensitivityInsulin sensitivity was measured with glucose infusion rate (GIR) when euglycermic hyperinsulinemia clamp technique was stable.5 Liver histological examinationThe paraffin sections, HE staining, light microscopy of liver pathology.6 The expression of PPARs mRNASemi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR) was used to detect the mRNA expression levels of PPARa and PPARy and to detect the impact of rosiglitazone and fenofibrate on the expression level of PPARy mRNA and PPARa mRNA respectively.7 Blood serum biochemistry inspectionAfter Serum samples was got, biochemical markers of change such as serum lipids and aminotransferase were detected by automatic biochemical analyzer. These procedures were assisted by the second biochemical room of Hospital of Hebei Medical University.Results1 The condition of the body weight rats in each groupAt the end of 16th week, NC and FC, FF, FR with the body weight of rats compared with a significant difference (P<0.01). In the model group, the FF group was significantly lower than the FC groups weight, and FR group growth trend.2 The changes in insulin sensitivityThe difference between the groups significantly, February 2 comparison showed NC group was significantly higher than other groups, and the FR group and the FF group were higher than FC group, and FF and FR group was differences.3 HE staining results are as followsThe naked eye and light microscopy findings NC group rat liver structure has been normal. FC group showed diffuse liver cells steatosis, necrosis and liver cells associated with infiltration of inflammatory cells, but no liver fibrosis; FF Group fat than FC changed significantly reduced, no obvious liver cell necrosis and inflammatory cell infiltration; The FF group lesions than FR and FC groups light.4 Liver PPARa mRNA and omentum PPARy mRNA expression changesDifferent among the four groups PPARa mRNA changes in the law are FF, NC, FR, FC group expression were lower. FF, FR group with statistical significance.omentum organizations PPAR y mRNA expression for FC> FF> NC> FR, FF and FR groups also had statistical significance.5 The concentrations of serum lipids,serum glucose and transaminaseTG and TC:Contents of TG in serum in FC group were obviously higher than those in NC,FF and FR group after 16 weeks; FF groups was lower than that in FR groups, Differences were considered to be statistically significant at P<0.05; Changes of levels of TC and TG were similar to those in serum, changes of levels of FF group were not obvious compared with those in FR group.ALT and AST:ALT blood comparison between the four groups were significantly different (P= 0.007<0.01), while FC group and FF, FR between groups was not significant (P> 0.05), but lower trend of AST ALT and similar changes.glucose:no comparison between the four groups was significant, but FC, and FF FR group which is higher than the trend of NC group.Conclusion1 Through the liver HE staining observed that all animals there are different degrees of diffuse liver cells steatosis, lobular, and the area of inflammatory cell infiltration, decreased insulin sensitivity, confirmed fatty liver insulin resistance in rats model of success after 12 weeks with high fat diet. 2 Weight, liver steatosis and the degree of inflammation was positively correlated with the IR, from which we can extrapolate that there is causal relation between IR and NAFLD.3 PPARamRNA was negatively correlated with the IR. PPAR y mRNA was positively correlated with the IR. PPARs agonists can be used to improve insulin resistance and hepatic steatosis, inflammation and necrosis, to reduce blood TC, TG which probably become potential drugs for treating patients with NASH in the future.