Regulation of intestinal Fgf15 and hepatic Cyp7a1 by ursodeoxycholic (UDCA) related to an intact enterohepatic circulation. (A) C57BL/6 J mice (FXR WT) and Fxr knockout (FXR KO) animals were fed either chow or ursodeoxycholic (UDCA) 0.5% w/w diet for 7 days. (B) C57BL/6 J mice were either sham operated (Sham) or subjected to common bile duct ligation (BDL) with or without UDCA 0.5% (w/w) enriched diet for 7 days. (C) Experiments performed like in (B) using FXR WT and FXR KO mice pretreated with UDCA for 3 days before BDL or co-administered UDCA with BDL for 7 days. (D–F) Administration of 0.5% (w/w) UDCA enriched diet for 7 days in WT and knockout (KO) mice, including Asbt KO, Ostα KO and Asbt-Ostα DKO. n = 6–7, values represent the mean ± SEM. *p < 0.05, **p < 0.01, ***p < 0.001.