CYP1A1 and hydrops fetalis: Recently, some Lactobacillus strains have been reported to improve metabolic homeostasis in HF diet-fed mice through the modulation of indole derivatives in the gut, leading to stimulation of the intestinal AhR pathway.26 We measured the expression of three classical target genes of the nuclear receptor AhR in the ileum (Ahrr, Cyp1a1, and Cyp1b1).