Study On Part Of Pathogenesis Of High-fat Diet-induced Non-alcoholic Fatty Liver Disease

Objectives:The prevalence of nonalcoholic fatty liver disease(NAFLD) is increasing, The pathological type of NAFLD includes steatosis, non-alcoholic steatohepatitis(NASH),hepatic fibrosis and cirrhosis and progress of end-stage liver disease threatens human health. This paper aims to establish a NAFLD animal model caused by high-fat diets which is similar to human NAFLD pathogenesis and to research the effects of Transforming growth factor-p1(TGF-p1), Tumor necrosis factor-a(TNF-a), Adiponectin, Catalase in NAFLD.Methods:40 male C57BL/6J rats were divided into control group and model group randomly with 20 in each group. After being fed with normal diet for one week, the model group was fed with Lieber-DeCarli high-fat emulsions; while the control group was fed with normal diet. From the 3th weekend,2 mice in each group were tested to observe the pathological progress of steatosis and inflammation, by the end of 5th week the model were established, and all remained mice were sacrificed and the blood sample, liver tissue was reserved for test. Serum ALT, AST, TG, TC, glucose and liver tissue TG, TC were tested by biochemistry method. Elisa was employed for liver tissue TNF-a and Adiponectin test. SudanⅢstaining of liver tissue was performed on frozen section, and the tissue steatosis degree was evaluated under light microscope. The inflammation activity was also scored under light micros-cope after haematoxylin-eosin(HE) staining. TGF-β1 and catalase expression in liver were detected by means of immunohistochemical staining.Results:1.Serum AST, ALT, TG, TC, Glucose and liver tissue TG, TC:①Serum AST, ALT(IU/L), Glucose(mmol/L):AST and ALT level of model group (67.53±15.22,20.18±5.77 respectively) were increased significantly compared with control group (48.70±8.95,13.31±4.47 respectively) (p<0.05), while model group Glucose level (11.22±1.04) was significantly higher than control group (7.78±1.39) (P<0.01).②Serum TG, TC(mmol/L):TG level of model group (1.06±0.43) was increased significantly compared with control group (0.71±0.15) (P<0.05), while model group TC level (4.22±0.62) was significantly higher than control group (2.32±0.63) (P<0.01).③Liver tissue TG, TC(mg/g):Liver tissue TG level of model group (254.94±87.87) was increased significantly compared with control group (67.77±17.61) (P<0.01), while model group liver tissue TC level (84.69±44.54) was significantly higher than control group (40.62±21.33) (P<0.05).2.The degree of steatosis:①SudanⅢstaining:Control group had no orange particles in liver cell and model group had a number of orange particles in liver cell under the microscope.②HE staining:Steatosis was not seen in normal group, while model group liver cells occurred steatosis generally, severe lipid degeneration were found, the disparity of severity was significantly compared with control group (P<0.01).3.Inflammation and related factors:①HE staining:No inflammation cell infiltrated in normal group, while portal inflammation occurred in hepatic lobule of model group, The score of inflammation activity of model group (4.31±1.08) were increased significantly compared with control group(P<0.01).②Liver tissue TNF-a(pg/g):Liver tissue TNF-a level of mo-del group (60.71±10.52) was increased significantly compared with control group (49.47±11.14) (P<0.05).③Liver tissue TGF-pl:Immuno histochemical staining displayed that the control group positive express cells is very few, the model group positive express cell increased significantly(P<0.01), was tan-yellow particles.4.Adiponectin,Catalas:①Adiponectin(ng/g):Liver tissue Adiponectin level of model group (9.54±1.60) was decreased significantly compared with control group (17.32±5.34) (P<0.05).②Catalase:Immunohistoc-hemical staining display that there were more positive cells in control group, the model group was fewer than control group (P<0.01).Conclusion:1.Using Lieber-DeCarli high-fat-diet fed mice 5 weeks continuously can form NAFLD animal model which is similar to humans NAFLD.2.Liver tissue catalase expression decreased and TGF-βexpression increased can promote NASH.3.Liver tissue Adiponectin level reduced and TNF-a increased play an important role in NAFLD pathogenesis.