Quantification of changed urinary metabolites involved in (A) tyrosine metabolism, (B) phenylalanine metabolism, and (C) tryptophan metabolism. (D,E) Quantification of tryptophan-related metabolites in serum sample (D) and cecum content (E) of mice treated with vehicle and antibiotics. (F) AHR mRNA expression in the colon of mice treated with vehicle and antibiotics. Keys: C, control mice; A, control mice treated with antibiotics; PAA, phenylacetic acid; Phe, phenylalanine; Trp, tryptophan; Tyr, tyrosine. Data are presented as mean ± SD; n=8 per group; *P<0.05, **P<0.01, and ***P<0.001, by two-tailed Student’s t test or Mann−Whitney test.