Upregulation of caveolin-1 and SR-B1 in mice with non-alcoholic fatty liver disease

BACKGROUND:Non-alcoholic fatty liver disease(NAFLD)is one of the most frequent causes of liver diseases,with markedly increased prevalence.However,its mechanisms are not clear.The present study was undertaken to illustrate the role of caveolin-1(cav1)and the scavenger receptor class B type 1(SR-B1)in NAFLD.METHODS:Adult male C57BL/6 mice were fed with a normal diet or high fat and cholesterol(HFC)diet for 14 weeks.The mice were sacrificed to collect plasma and harvest the liver;their plasma lipid concentration was measured.Hepatic cav1and SR-B1 mRNA and protein expression were determined by real-time quantitative polymerase chain reaction(qPCR)and Western blotting,respectively.In order to study cav1 and SR-B1distribution and change in hepatocytes,immunohistochemical analysis was performed.RESULTS:HFC diet increased plasma lipids,induced NAFLD and increased the liver/body weight ratio.Compared to the control mice(n=6),the mRNA and protein levels of cav1 and SR-B1 in liver tissue of the NAFLD mice(n=12)increased significantly(cav1 mRNA:1.536±0.226 vs 0.980±0.272,P【0.05;protein:0.643±0.240 vs 0.100±0.130,P【0.01;SR-B1 mRNA:1.377±0.125 vs 0.956±0.151,P【0.01;protein:2.156±0.507vs 0.211±0.211,P【0.01).Furthermore,both cav1 and SR-B1immunoreactivity increased and their distribution was also changed,mainly in the plasma membrane of hepatocytes,cytoplasm and membrane of lipid droplets and around.CONCLUSION:NAFLD is associated with increased concentration of plasma lipids and upregulation of hepatic cav1 and SR-B1 gene and protein expressions,which indicate that cav1 and SR-B1 might play crucial roles in the pathogenesis of NAFLD.