In this study, tryptophan supplementation significantly increased the gene expression of IDO1, TPH2, and SLC3A1 in the duodenal tissues, as well as increasing TPH2 and SLC3A1 in the colonic tissues, of CRS-exposed mice, indicating the important role of tryptophan in metabolic pathways under stress conditions. Here, IDO1 is linked to congenital rubella syndrome.