Species difference in cholesterol 7α-hydroxylase expression of rabbit and rat liver microsomes after bile duct ligation

Abstract

Background Bile duct ligation (BDL) produces a good animal model for investigation of the metabolic changes in obstructive jaundice. The aim of this study was to investigate the species difference in expression of cholesterol 7α-hydroxylase (7α-hydroxylase) in rabbits and rats after BDL. Materials and methods Ten male New Zealand white rabbits weighing 2.5–3 kg and 12 male Wistar strain rats weighing 250–300 g were used. Half the animals underwent BDL, and half were sham operated (Sham). The animals were sacrificed on day 5 after operation. The livers were harvested, and levels of mRNA and 7α-hydroxylase activity were determined. Concentrations of serum bilirubin and bile acids were also measured. Results In BDL rats, the levels of mRNA were increased 30%, and 7α-hydroxylase activity was three times that of the Sham group. In BDL rabbits, however, these values were approximately 60 and 50% lower than the Sham group, respectively. Serum bile acid concentrations increased up to 13 times in BDL rabbits and 70 times in BDL rats over that of the Sham groups. Serum cholesterol and serum total bilirubin concentration also increased after BDL in both animals. Conclusion These results suggest that there is a species difference in the expression of 7α-hydroxylase after BDL in rabbits and rats and the reason for this difference is most likely pretranslational regulation.