title: Differential regulation of bile acid and cholesterol metabolism by the farnesoid X receptor in Ldlr -/- mice versus hamsters.
abstract: Modulating bile acid synthesis has long been considered a good strategy by which to improve cholesterol homeostasis in humans. The farnesoid X receptor (FXR), the key regulator of bile acid synthesis, was, therefore, identified as an interesting target for drug discovery. We compared the effect of four, structurally unrelated, synthetic FXR agonists in two fat-fed rodent species and observed that the three most potent and selective agonists decreased plasma cholesterol in LDL receptor-deficient (Ldlr (-/-)) mice, but none did so in hamsters. Detailed investigation revealed increases in the expression of small heterodimer partner (Shp) in their livers and of intestinal fibroblast growth factor 15 or 19 (Fgf15/19) in mice only. Cyp7a1 expression and fecal bile acid (BA) excretion were strongly reduced in mice and hamsters by all four FXR agonists, whereas bile acid pool sizes were reduced in both species by all but the X-Ceptor compound in hamsters. In Ldlr (-/-) mice, the predominant bile acid changed from cholate to the more hydrophilic β-muricholate due to a strong repression of Cyp8b1 and increase in Cyp3a11 expression. However, FXR agonists caused only minor changes in the expression of Cyp8b1 and in bile acid profiles in hamsters. In summary, FXR agonist-induced decreases in bile acid pool size and lipophilicity and in cholesterol absorption and synthesis could explain the decreased plasma cholesterol in Ldlr (-/-) mice. In hamsters, FXR agonists reduced bile acid pool size to a smaller extent with minor changes in bile acid profile and reductions in sterol absorption, and consequently, plasma cholesterol was unchanged.
authors: Cardiovascular and Metabolic Diseases DTA, F. Hoffmann-La Roche AG, Basel, Switzerland. christophe.gardes@roche.com
authors: Christophe
authors: C
authors: Gardès
authors: Evelyne
authors: E
authors: Chaput
authors: Andreas
authors: A
authors: Staempfli
authors: Denise
authors: D
authors: Blum
authors: Hans
authors: H
authors: Richter
authors: G Martin
authors: GM
authors: Benson
mesh_terms: D000818:Animals; D001647:Bile Acids and Salts / Q000235:genetics / Q000378:metabolism*; D002784:Cholesterol / Q000378:metabolism*; D002790:Cholesterol 7-alpha-Hydroxylase / Q000378:metabolism; D019826:Cholic Acid / Q000378:metabolism; D006224:Cricetinae; D051544:Cytochrome P-450 CYP3A / Q000378:metabolism; D005786:Gene Expression Regulation; D050356:Lipid Metabolism; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D018160:Receptors, Cytoplasmic and Nuclear / Q000819:agonists / Q000235:genetics / Q000378:metabolism*; D013253:Steroid 12-alpha-Hydroxylase / Q000378:metabolism; D000099150:Receptor, Farnesoid X-Activated
chemical_list: D001647:Bile Acids and Salts; D002784:Cholesterol; D002790:Cholesterol 7-alpha-Hydroxylase; D019826:Cholic Acid; D051544:Cytochrome P-450 CYP3A; D008565:Membrane Proteins; D018160:Receptors, Cytoplasmic and Nuclear; D013253:Steroid 12-alpha-Hydroxylase; D000099150:Receptor, Farnesoid X-Activated; C496508:Cyp3a11 protein, mouse; C502772:Cyp7a1 protein, mouse