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. 2022 Jul 5;135(10):1163–1171. doi: 10.1097/CM9.0000000000002156

Figure 2.

Figure 2

Bile acid synthesis and enterohepatic circulation. Bile acids are exclusively synthesized from cholesterol in the hepatocytes via two pathways, classical (neutral) pathway and alternative (acidic pathway) via multiple enzymatic reactions. Under normal physiological conditions, bile acids circulate from the liver to the bile, intestinal lumen, and return to the liver via the portal vein. More than 95% of bile acids are reabsorbed by the enterocytes in the ileum, and only 5% will be metabolized by the gut microbiome and excreted via feces. The lost bile acids will be replaced by de-novo synthesis in the liver. The composition of the bile acid pool in mice is different from that in humans. Α-MCA: α-muricholic acid; BACS: Bile acyl-CoA synthetase; BAAT: Bile acid-CoA: amino acid N-acyltransferase; β-MCA: Beta-Muricholic acid; CA: Cholic acid; CDCA: Chenodeoxycholic acid; CYP27A1: Cholesterol 27α-hydroxylase; DCA: Deoxycholic acid; GCA: Glycocholic acid; GCDCA: Glycine chenodeoxycholic acid; LCA: Lithocholic acid; MDCA: Murideoxycholic acid; TCA: Taurocholic acid; TCDCA: Taurine chenodeoxycholic acid. The figure was created via BioRenders.com.