Ontogenetic Development and Spatial Distribution of the Ileal Apical Sodium-Dependent Bile Acid Transporter and the Ileal Lipid-Binding Protein in ApoE Knockout and C57BL/6 Mice

Abstract

Background: Although apoE-/- mice are characterized by hypercholesterolemia, the bile acid enterohepatic circulation, which plays a crucial role in cholesterol homeostasis, has not been examined in these mice. The differences between apoE-/- and C57BL/6 mice in expression of the ileal ASBT and ILBP and in intestinal bile acid absorption were studied. Methods: The intestinal tissues of the fetal, neonatal and post-weaning mice were processed for immunohistochemistry. Body retention and fecal excretion of 75SeHCAT were measured. The bile acid pool size and its composition were analysed by HPLC. Results: In apoE-/- and C57BL/6 mice, the bile acid pool size was 75 ± 13 and 78 ± 13 μmol/ 100 g body weight, respectively, while the ratio of cholic acid/ β -muricholic acid was 1.8 ± 0.3 and 1.4 ± 0.3 ( P < 0.05), respectively. The daily body retention of 75SeHCAT was 48% ± 1.8% in C57 black mice and 58.4% ± 2.7% in apoE-/- mice ( P < 0.05). In both mouse strains, ASBT expression in the small intestine was found in the near-term fetal and post-weaning mice, while ILBP expression was found in all postnatal mice. In the post-weaning mice, ILBP expression was limited to the distal 25%-30% of the small intestine, while ASBT expression was limited to the distal 18%. Conclusions : The bile acid enterohepatic circulation in apoE-/- mice probably does not differ greatly from that in C57BL/6 mice.

• Asbt
• Bile Acids
• Ilbp
• Mice
• Ontogenesis
• 75sehcat