Mouse hepatic cytochrome P-450 isozyme induction by 1,4-bis[2-(3,5-dichloropyridyloxy)]benzene, pyrazole, and phenobarbital.
The effects of 1,4-bis[2-(3,5-dichloropyridyloxy)]benzene (TCPOBOP) and pyrazole on mouse hepatic cytochrome P-450 isozyme expression were compared to the P-450 induction pattern elicited by phenobarbital. TCPOBOP and PB administration caused a similar induction profile by increasing microsomal protein and cytochrome P-450 content and the catalytic activities of several monooxygenases in DBA/2N and AKR/J mice. There were, however, several quantitative and some qualitative differences in the induction profile caused by phenobarbital and TCPOBOP. A few strain-related differences were also observed. Immunoblot analysis with polyclonal anti-coumarin hydroxylase (P-450Coh) antibody and epitope-specific monoclonal antibodies 1-7-1 and 2-66-3 showed that both phenobarbital and TCPOBOP increase the amount of P450IIB and P-450Coh. TCPOBOP caused a more pronounced increase in the amount of P-450IIB than phenobarbital, and TCPOBOP also caused an increase in the amount of P-450IA2. These data suggest that in the mouse, TCPOBOP increases mainly the expression of P-450 isozymes responsive to phenobarbital. The effects of pyrazole differed greatly from those caused by TCPOBOP and phenobarbital. In the DBA/2N mice, pyrazole increased coumarin 7-hydroxylation 9.4-fold, whereas in the AKR/J mice the activity was induced only to a level equivalent to the DBA/2N basal level. In immunoblot experiments with anti-P-450Coh antibody, the amount of P-450Coh was considerably higher in DBA/2N mice treated with phenobarbital, TCPOBOP, or pyrazole in comparison with the AKR/J mice, indicating a strain specificity in the inducibility of coumarin 7-hydroxylase by pyrazole.
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D015153:Blotting, Western; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis*; D004790:Enzyme Induction / Q000187:drug effects; D005721:Glutamate-Cysteine Ligase / Q000378:metabolism; D007527:Isoenzymes / Q000096:biosynthesis; D051379:Mice; D008815:Mice, Inbred Strains / Q000378:metabolism; D008862:Microsomes, Liver / Q000201:enzymology*; D006899:Mixed Function Oxygenases / Q000096:biosynthesis*; D008970:Molecular Weight; D010634:Phenobarbital / Q000494:pharmacology*; D011720:Pyrazoles / Q000494:pharmacology*; D011725:Pyridines / Q000494:pharmacology*
D000911:Antibodies, Monoclonal; D007527:Isoenzymes; D011720:Pyrazoles; D011725:Pyridines; C031280:pyrazole; C028474:1,4-bis(2-(3,5-dichloropyridyloxy))benzene; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D005721:Glutamate-Cysteine Ligase; D010634:Phenobarbital