TY - JOUR T1 - Aryl Hydrocarbon Receptor Activity of Tryptophan Metabolites in Young Adult Mouse Colonocytes JF - Drug Metabolism and Disposition JO - Drug Metab Dispos SP - 1536 LP - 1543 DO - 10.1124/dmd.115.063677 VL - 43 IS - 10 AU - Yating Cheng AU - Un-Ho Jin AU - Clint D. Allred AU - Arul Jayaraman AU - Robert S. Chapkin AU - Stephen Safe Y1 - 2015/10/01 UR - http://dmd.aspetjournals.org/content/43/10/1536.abstract N2 - The tryptophan microbiota metabolites indole-3-acetate, indole-3-aldehyde, indole, and tryptamine are aryl hydrocarbon receptor (AhR) ligands, and in this study we investigated their AhR agonist and antagonist activities in nontransformed young adult mouse colonocyte (YAMC) cells. Using Cyp1a1 mRNA as an Ah-responsive end point, we observed that the tryptophan metabolites were weak AhR agonists and partial antagonists in YAMC cells, and the pattern of activity was different from that previously observed in CaCo2 colon cancer cells. However, expansion of the end points to other Ah-responsive genes including the Cyp1b1, the AhR repressor (Ahrr), and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-inducible poly(ADP-ribose) polymerase (TiParp) revealed a highly complex pattern of AhR agonist/antagonist activities that were both ligand- and gene-dependent. For example, the magnitude of induction of Cyp1b1 mRNA was similar for TCDD, tryptamine, and indole-3-acetate, whereas lower induction was observed for indole and indole-3-aldehyde was inactive. These results suggest that the tryptophan metabolites identified in microbiota are selective AhR modulators. ER -