Role of zebrafish cytochrome P450 CYP1C genes in the reduced mesencephalic vein blood flow caused by activation of AHR2

► We examine the roles of zebrafish CYP1C1 and CYP1C2 in TCDD developmental toxicity. ► TCDD induces mRNA expression of both CYP1Cs in the mesencephalic vein. ► Knockdown of each CYP1C prevents mesencephalic circulation failure by TCDD. ► Induced CYP1Cs are involved in reduction of mesencephalic vein blood flow by TCDD.