in liver (1). In mouse liver, COH activity can be strongly induced by pyrazole, while in rat liver COH is not detectable even after treatments with pyrazole (6). CYP2A5 expression or its catalytic activity (COH) is highly inducible in mouse liver by diverse hepatotoxic chemicals that are neither structurally similar nor generally considered to be CYP inducers (1). However, the relationship between CYP2A5 induction and liver injury is still unclear.
