Inhibition Of Rosiglitazone On The Expression Of TNF-α In Rats With Nonalcoholic Steatohepatitis

Objectives: Non-alcoholic steatohepatitis (NASH) is correlated with inheritance-environment-metablism, which is a clinic histologic syndrome that characterized by diffuse steatosis and inflammation. The etiopathogenesis of NASH is not clear. Somebody put forward"two Hits"may be the etiopathogenesis of NASH. Insulin-resistance are"The First Hit"that make the fat deposits on the hepatocyte and lead to fatty liver."The Second Hit"involves oxidative stress and lipidperoxidation, cytokines, which lead steatosis hepatic cells to be inflammatory, necrosis and fibrosis. Rosiglitazone which is the specificity insulin-sensitizing drug, can activate PPAR-γand prohibit Kuffer cell to release many inflammatory agents, such as tumor necrosis factor-α, Interleukin-8, and so on. We set up rat model of NASH. At the same time, Rats in the treated group were treated by intragastric rosiglitazone. The level of TNF-αin serum and the expression TNF-αmRNA in the liver was determined. Combined with the biochemical indexes and the liver pathology, we can investigate the therapeutic effects of insulin-sensitizing drugs, rosiglitazone in rats with NASH.Methods : Forty-five male Wistar rats were randomized into two groups: normal control group (n = 10, fed with normal food) and model group (n = 35, fed with high-fat food). Four rats were selected randomly from the model group and were killed to undergo pathological examination of the liver at 16th week from the beginning. When the NASH model of rats were set up, the remaining thirty-one NASH rats were subdivided into four subgroups: model group (eight rats to be fed continuously with high-fat food), high dose treatment group (eight rats fed with high-fat food and rosiglitazone 4mg/kg·d by gastric perfusion), low dose treatment group (eight rats fed with high-fat food and rosiglitazone 1mg/kg·d by gastric perfusion), and rosiglitazone+dietary treatment group (seven rats fed with normal food and rosiglitazone 1mg/kg·d by gastric perfusion). At end of the 28th week, all rats were killed to collect serum to measure the levels of total cholesterol(TC), triglyceride(TG), alanine transaminase(ALT), aspartate transaminase (AST), and tumor necrosis factor-α( TNF-α). The specimens of liver were stained with HE, SudanⅣand then studied microscopically. The expression of TNF-αmRNA was determined by RT-PCR.Results:1 The general state: There was no death in all rats. Normal rats all have good appetite, their fur was bright, psychosis was good and weight increased. Model rats have bad appetite, which were thin, less movement, their fur has no shine and psychosis was bad. After the 28th week, the body weight of rats in model group decrease than before. The psychosis, appetite and movement of treated rats were between the normal rats and model rats.2 The examination of biochemical indexes in serum: The level of serum TC(2.95±0.32 mmol/L), TG(0.88±0.17 mmol/L), ALT(96.63±14.16U/L), and AST(156.13±14.74U/L) in the model group increased significantly. The level of serum TC(2.03±0.21 mmol/L, 2.49±0.31mmol/L, 2.00±0.24 mmol/L), TG(0.54±0.14mmol/L, 0.71±0.14 mmol/L, 0.52±0.14 mmol/L), ALT(67.38±13.68U/L, 82.38±12.01U/L, 45.14±12.05U/L), and AST(94.25±15.70U /L, 129.5±16.70U/L, 91.00±16.31U/L) in the high dose, low dose and rosiglitazone +dietary treatment groups were all lower than those of the model group. The level of serum TC, TG, ALT and AST in the rosiglitazone+dietary treatment group were significantly declined in comparison with the high dose and low dose group.3 Pathological observation: The normal livers were henna and bright. The model rat livers were buff and obviously large, which focal degeneration of yellow and white can be seen. The sections were greasy and dim. The normal hepatocyte arranged in radiation by the center of the central veins under light microscope. Suffusion microvesicular fatty degeneration were observed in hepatic tissue of the model rats. The fatty degeneration and necrosis decreased in treated rat livers.4 The level of serum TNF-αwas determined by ELISA: The level of serum TNF-αin the high dose, low dose and rosiglitazone +dietary treat groups were (38.660±3.543pg/ml), (43.211±3.77pg/ml), (32.024±3.804pg/ml) respectively. They were significantly lower than that of the model group (48.231±3.381pg/mL). The level of serum TNF-αin the rosiglitazone +dietary treat group had decreased remarkably comparing with the high dose, low dose treat group.5 The expression of TNF-αmRNA in the livers of rats by means of RT-PCR: There was nearly no positive expression of TNF-αmRNA in the livers of the normal group. With the progress of NASH, the expression of TNF-αmRNA become more intense. In the model group, the expression of TNF-αmRNA in the liver were increased obviously. The expression of TNF-αmRNA was lower in the livers of the high dose, low dose and rosiglitazone+dietary treat groups (0.714±0.059, 0.851±0.056, 0.424±0.057) than that of the model group (0.954±0.063). The expression of TNF-αmRNA was obviously weaker of the high dose group than that of low dose group and stronger than that of rosiglitazone+dietary treat group (p<0.01).Conclusion:1 Rat model of NASH could be developed by feeding with high-fat food gradually.2 Hyperlipidemias destroy the homeostasis of lipoprotein metabolism in liver of rats and activate the oxidative stress, which lead to releasing cytokines .3 In the process of NASH, the cytokines such as TNF-αplay an important role.4 Expression of TNF-αmRNA is downregulated by insulin-sensitizing drug, which can depress inflammatory response efficiently. This provide rational basis for preventing and treating patients with NASH by using rosiglitazone.