Male F344 rats were treated with a chemical (aniline, nitrobenzene, 2-
methoxy-p-phenylenediamine, 2-methoxy-4-nitroaniline or 2-methoxy-4-ni
troazobenzene) produced by the azo-reduction and/or N-oxidation of 2-m
ethoxy-4-amino-azobenzene, a selective inducer of cytochrome P450IA2 (
CYP1A2), and their effects on the induction of CYP1A enzymes in the li
ver were examined in terms of the protein and mRNA amounts. 2-Methoxy-
4-nitroaniline and 2-methoxy-4-nitroazobenzene, but not other compound
s tested, induced CYP1A enzymes, especially CYP1A2, as assessed by Wes
tern blotting and Northern blotting. It is noteworthy that 2-methoxy-4
-nitroaniline was more selective than 2-methoxy-4-aminoazobenzene for
induction of CYP1A2, and it has the smallest molecular size among the
known CYP1A2 inducers.