Bile Acid Physiology

• DOI: 10.5604/01.3001.0010.5493
• Publication Date: 2017-10-28T13:08:46Z
• Authors: Agostino Di Ciaula; Gabriella Garruti; Raquel Lunardi Ba...; Emilio Molina-Molina; Leonilde Bonfrate; David Q.-H. Wang; Piero Portincasa
• Keywords: 0301 basic medicine; Bile acids. Microbiota. FXR. Bile; 571; Bacteria; Microbiota; Specialties of internal medicine; Gallbladder; Lipid Metabolism; Bile acids; Gastrointestinal Microbiome; Bile Acids and Salts; Intestines; Feces; 03 medical and health sciences; FXR; RC581-951; Liver; Enterohepatic Circulation; Bile; Animals; Humans; Intestinal Mucosa; Energy Metabolism; Signal Transduction

The primary bile acids (BAs) are synthetized from colesterol in the liver, conjugated to glycine or taurine to increase their solubility, secreted into bile, concentrated in the gallbladder during fasting, and expelled in the intestine in response to dietary fat, as well as bio-transformed in the colon to the secondary BAs by the gut microbiota, reabsorbed in the ileum and colon back to the liver, and minimally lost in the feces. BAs in the intestine not only regulate the digestion and absorption of cholesterol, triglycerides, and fat-soluble vitamins, but also play a key role as signaling molecules in modulating epithelial cell proliferation, gene expression, and lipid and glucose metabolism by activating farnesoid X receptor (FXR) and G-protein-coupled bile acid receptor-1 (GPBAR-1, also known as TGR5) in the liver, intestine, muscle and brown adipose tissue. Recent studies have revealed the metabolic pathways of FXR and GPBAR-1 involved in the biosynthesis and enterohepatic circulation of BAs and their functions as signaling molecules on lipid and glucose metabolism.