Effect Of Berberine On Expression Of UCP2 MRNA And UCP2 Protein Of Hepatic Tissue In NAFLD Rats

Objective:To observe the effect of Berberine on UCP2 mRNA and UCP2 protein expression in hepatic tissue of nonalcoholic fatty liver disease(NAFLD) in rats and to explore their molecular mechanismMethods:66 male SD rats were randomly divided into two groups:high fat diet group(n=56,fed with high fat diet) and the normal group(n=10,fed with normal diet).At the end of 12th week,6 rats were randomly selected for hepatic histopathology examination and NAFLD rat model was confirmed to be successfully duplicated.Then the remaining 50 model rats were subdivided into 5 equal subgroups:high-dose berberine group(high-dose of berberine by gastric perfusion),low-dose berberine group(low-dose of berberine by gastric perfusion), Dongbaogantai treatment group(Dongbaogantai by gastric perfusion),model group and natural recovery group.Rats in the remaining 3 groups were fed with equal stilled water by perfusion and meantime rats in all groups except in model group were fed with normal diet. 20 weeks later,all rats were anesthetized by 3%pentobarbital sodium through intraperitoneal injection.TG,TC,AST and ALT contents in the serum were detected by automatic biochemical analyzer.Plasma insulin concentration was measured by radioimmunoassay.The expression levels of UCP2mRNA and UCP2 proteins in liver tissue were respectively examined by reverse transcription polymerase chain reaction(RT-PCR) and Immunohistochemistry.Results:(1) Compared with normal group,AST,ALT,FBG,FINS and LDL-C contents in the serum and TC,TG levels in hepatic homogenate in model group were significantly increased (P＜0.01),while serum HDL-C and ISI levels were decreased(P＜0.01).The expression of UCP2 mRNA and positive cell numbebers of UCP2 in liver tissue were dramatically increased in model group compared to normal group(P＜0.01).(2) Compared with the model group,contents ofAST,ALT and LDL-C in the serum and TC, TG levels in hepatic homogenate in the treatment groups were obviously decreased(P＜0.01), and serum HDL-C content was increased(P＜0.01),while no significant difference was found between the treatment groups(P＞0.05).Compared to model group,FBG and FINS levels in serum in threatment groups and natural group were obviously decreased(P＜0.01 or P＜0.05 );High-dose and low-dose berberine had significantly raised ISI(P＜0.01) and down-regulated expression of UCP2 mRNA and UCP2 protein in the liver tissue. (P＜0.01).However,for the above parameters,no significant difference was shown in Dongbaogantai group and natural recovery group compared to model group(P＞0.05).(3) Light microscope observation revealed medium fatty degeneration in hepatocytes in model group:swelling of hepatocytes and different sizes of lipid droplets inside the cytoplasm. Infiltration of inflammatory cells was shown in the portal area of model rats.No piecemeal necrosis,bridging necrosis and fibrosis were seen in the hepatic tissue of model rats.In high-dose and low-dose berberine groups,there shows mild fatty degeneration in hepatocytes but no obvious infiltration of inflammatory cells.In Dongbaogantai group and natural recovery group,there shows fatty degeneration from mild to medium degrees in hepatocytes and small amount of inflammatory cells.Conclusion:(1) Rat model of NAFLD were successfully duplicated by sustained high fat diet. Characteristics such as hepatocyte steatosis,decreased insulin sensitivity,hyperinsulinemia, dyslipidemia,and increased expression of UCP2mRNA and protein can be seen in model group rats.(2) Diet control can reverse hepatic steatosis in the early stage of NAFLD(3)Berberine combined with diet control can promote recovery of hepatocyte steatosis in model group.They may work by down-regulating UCP2mRNA and UCP2 protein expression in liver and improving lipid metabolism and insulin resistance.(4) Berberine shows certain therapeutic effect on NAFLD,while the most suitable therapy period needs further research.