| Object:Establish rat non-alcoholic fatty liver disease(NAFLD) model with high-fat diet;To study the effects of insulin resistance(IR), c-Jun N-terminal kinase-1(JNK1),inflammatory reaction on the pathogenesis of NAFLD;To observe the effects of pioglitazone on NAFLD and the expression of JNK1 in liver;to explore the mechanisms of PIO on NAFLD.Method:forty male SD rats were randomly divided into normal diet group(NG,n=16),which were fed on normal diet,and high-fat diet group(HG,n=24),which were fed on high-fat diet(normal diet adding 1% cholesterol and 14%lard).At the end of 8th week,8 rats were randomly drew off from each group to identify the NAFLD model,and these rats were named NG8w group and HG8w group.At the beginning of 9th week, all rats of HG were randomly divided into two groups:HG12w(n=8),the rats of this group were fed on high-fat diet sequentially,and were given normal sodium chloride 2ml every day for 4weeks;pioglitazone group(PG,n=8),the rats of this group were continued to be fed on high-fat diet,and were given pioglitazone 10mg-kg-1d-1 for 4 weeks. Fasted and weighed all the rats before executing.After executing,serum alanine aminotransferase(ALT),aspartate aminotransferase(AST) trglyceride(TG),total cholesterol(TC),fasting blood glucose(FBS), fasting insulin(Fins),free fatty acids(FFAs) and tumor necrosis factor-α(TNF-α) were measured by drawing blood from portal vein;then, the liver was dissociated and weighed,fasting insulin resistance index(FIRI)was calculated;the liver tissues were made to 10%liver homogenate for measuring the levels of liver TG,TC,FFAs.Hepatic steatosis was assessed by using H-E stain sections,the expression of JNK1 in liver tissue was detected by using immunohistochemistry method.Result:(1) Compared to the corresponding period of NG,the weight,liver index,levels of serum ALT,AST,TG,TC,Fins,FFAs,TNF-α,FIRI and levels of liver homogenate TG,TC,FFA of HG were higher,there were statistics differences between them(p＜0.05);however there was no significant difference in FBS of each group;Vacuolar hepatic steatosis was observed in HG8W rats under the light microscope; the diffused hepatic steatosis and lobular inflammatory-cell infiltration and spotty necrosis were observed in HG12W rats under the light microscope;(2) Compared to HG12w rats,the liver index,levels of serum ALT,AST,TG,Fins,FFAs,TNF-α,FIRI and levels of liver homogenate TG,FFAs of PG were lower,there were significant statistics differences(p＜0.05);but all the indexes didn't completely return to the same as those of NG12W group.(3) hepatic steatosis and balloon-like changes could be observed in PG under the light microscope,the lobular inflammatory-cell were also could be observed seldom,but compared to HG12w,the hepatic steatosis of PG were more less; (4)immunohistochemistry showed that:JNK1-positive liver cells stained brown under the light microscope,normal control group had no significant JNK1-positive liver cells,HG8w,HG12w have a strong expression of JNK1,For the performance of the cytoplasm and/or nucleus diffuse brown granular,compared with NG rats,there were a significant difference(p＜0.01),and positive particles are mainly located in the liver cell nucleus and cytoplasm;Expression of JNK1-positive in PG is weaker than HG12W,for the performance of the particles shaders and the extent of JNK1-positive cells were small,there were statistics differences(p＜0.01);but expression of JNK1-positive in PG is stronger than NG12W,there were statistics differences(p＜0.01).(5)FIRI had positive correlation with serum hepatic steatosis,TNF-α,FFAs and the expression of JNK1.TNF-αand FFAs had positive correlation with the expression of JNK1.Conclusion:1.The SD rat NAFLD model has been successfully estabolished by constantly feeding high-fat diet for 8 weeks.2.Pioglitazone can improve IR,have antiinflammatory effect and played therapeutic role in SD rat NAFLD.3.Pioglitazone may reduce TNF-α,FFAs and thus inhibiting expression of JNK1,and then improve IR.
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