Hyper- and hypo-induction of cytochrome P450 activities with Aroclor 1254 and 3-methylcholanthrene in Cyp1a2(−/−) mice
| Autor: | James P. Kushner, Mark L. Westbroek, Michael R. Franklin, Dorinda D Arch, Laura B. Hathaway, John D. Phillips, Melissa L. Barker |
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| Rok vydání: | 2009 |
| Předmět: |
Male
medicine.medical_specialty Toxicology Article Hydroxylation Mice chemistry.chemical_compound Cytochrome P-450 Enzyme System Cytochrome P-450 CYP1A2 Internal medicine medicine Animals Inducer Testosterone chemistry.chemical_classification biology Bufuralol CYP1A2 Cytochrome P450 General Medicine Chlorodiphenyl (54% Chlorine) Polychlorinated Biphenyls Mice Inbred C57BL Endocrinology Enzyme Liver chemistry Methylcholanthrene biology.protein Female Gene Deletion |
| Zdroj: | Chemico-Biological Interactions. 182:220-226 |
| ISSN: | 0009-2797 |
| DOI: | 10.1016/j.cbi.2009.09.007 |
| Popis: | The response of hepatic mono-oxygenase activities to Aroclor 1254 or 3-methylcholanthrene was investigated in wild-type and Cyp1a2(-/-) mice. Cytochrome P450 concentrations were similar in naive Cyp1a2(-/-) and wild-type mice. There was no difference between naive wild-type and Cyp1a2(-/-) animals in 7-ethoxyresorufin and 7-ethoxy-4-trifluoromethylcoumarin dealkylase activities, nor was the induction response after 3-methylcholanthrene any different between the two genotypes. However, both activities were induced to a higher extent in Cyp1a2(-/-) mice after Aroclor 1254. In contrast, 7-pentoxyresorufin dealkylation activity was lower in Cyp1a2(-/-) mice and this differential was maintained during induction by both agents. 7-Methoxy- and 7-benzoxyresorufin dealkylation activities were also lower than wild-type in naive Cyp1a2(-/-) animals and during 3-methylcholanthrene induction, but showed accelerated induction in Cyp1a2(-/-) mice with Aroclor 1254. Bufuralol 1'- and testosterone 6beta-hydroxylation activities, and P450 characteristics were evaluated 48h after inducer administration. Bufuralol 1'-hydroxylation, a sexual dimorphic activity (female>male) showed no genotype differences in naive animals. Activity changes varied across gender and genotype, with 3-methylcholanthrene and Aroclor 1254 inducing in male Cyp1a2(-/-), and Aroclor 1254 inducing in female wild-type. Testosterone 6beta-hydroxylation activity was 16% higher in Cyp1a2(-/-) mice and neither 3-methylcholanthrene nor Aroclor 1254 elicited induction. After Aroclor 1254, a 24% increase in P450 concentration with a hypsochromic shift in the ferrous-CO maximum characteristic of CYP1A enzymes occurred in wild-type, compared to no change in either parameter in Cyp1a2(-/-) mice. Induction changes with 3-methylcholanthrene were greater in wild-type mice, a 60% increase in concentration and approximately 2 nm hypsochromic shift versus a 10% increase and approximately 1nm hypsochromic shift in Cyp1a2(-/-) mice. The study demonstrates that deletion of a single P450 can profoundly affect the induction response, as monitored with activities of other P450s, in a manner unrelated to the contribution of the deleted P450 to the activity. |
| Databáze: | OpenAIRE |
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