Effect of obstructive jaundice on the regulation of hepatic cholesterol metabolism in the rat. Disappearance of abcg5 and abcg8 mRNA after bile duct ligation.

The purpose of this study is to evaluate the effect of bile duct ligation (BDL) on changes of lipoprotein metabolism and hepatic gene expressions that are important for cholesterol metabolism. In male rats serum, very low-density lipoprotein cholesterol, low-density lipoprotein cholesterol and apolipoproteins B and E increased after 5 days of BDL compared with those of sham operation (control) group. Serum apolipoprotein A-IV concentration in the BDL group was lower than that in the control group. In both groups, there was no difference in hepatic lipid concentrations. Hepatic mRNA expressions of scavenger receptor B1, microsomal triglyceride transfer protein (mtp), HMG-coA reductase, cholesterol 7alpha-hydroxylase and multidrug resistance gene product 2 in the BDL group were significantly higher than that in the control group. The adipocyte determination and differentiation 1 mRNA expression in the BDL group was significantly lower than that in the control group. abcg5 and abcg8 mRNA expressions were remarkably decreased in the BDL group. In conclusion, in obstructive jaundice, metabolism of lipoprotein and proteins that are important for lipid metabolism are drastically changed probably for maintaining the hepatic lipid concentration. The remarkable down-regulation of the abcg5 and abcg8 may be an adaptive change reflecting the inability of biliary cholesterol excretion.