Evaluation of the precision-cut liver and lung slice systems for the study of induction of CYP1, epoxide hydrolase and glutathione S-transferase activities.
The principal objective was to ascertain whether precision-cut tissue slices can be used to evaluate the potential of chemicals to induce CYP1, epoxide hydrolase and glutathione S-transferase activities, all being important enzymes involved in the metabolism of polycyclic aromatic hydrocarbons. Precision-cut rat liver and lung slices were incubated with a range of benzo[a]pyrene concentrations for various time periods. A rise in the O-deethylation of ethoxyresorufin was seen in both liver and lung slices exposed to benzo[a]pyrene, which was accompanied by increased CYP1A apoprotein levels. Pulmonary CYP1B1 apoprotein levels and hepatic mRNA levels were similarly enhanced. Elevated epoxide hydrolase and glutathione S-transferase activities were also observed in liver slices following incubation for 24h; similarly, a rise in apoprotein levels of both enzymes was evident, peak levels occurring at the same time point. When mRNA levels were monitored, a rise in the levels of both enzymes was seen as early as 4h after incubation, but maximum levels were attained at 24 h. In lung slices, induction of epoxide hydrolase by benzo[a]pyrene was observed after a 24-h incubation, and at a concentration of 1 microM; a rise in apoprotein levels was seen at this time point. Glutathione S-transferase activity was not inducible in lung slices by benzo[a]pyrene but a modest increase was observed in hepatic slices. Collectively, these studies confirmed CYP1A induction in rat liver slices and established that CYP1B1 expression, and epoxide hydrolase and glutathione S-transferase activities are inducible in precision-cut tissue slices.
Pushparajah
Daphnee S
DS
Molecular Toxicology Group, School of Biomedical and Molecular Sciences, University of Surrey, Guildford, Surrey GU2 7XH, UK.
Umachandran
Meera
M
Plant
Kathryn E
KE
Plant
Nick
N
Ioannides
Costas
C
D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics / Q000378:metabolism*; D001564:Benzo(a)pyrene / Q000633:toxicity; D002274:Carcinogens, Environmental / Q000633:toxicity; D019363:Cytochrome P-450 CYP1A1 / Q000235:genetics / Q000378:metabolism; D065633:Cytochrome P-450 CYP1B1; D003600:Cytosol / Q000201:enzymology; D004851:Epoxide Hydrolases / Q000235:genetics / Q000378:metabolism*; D005982:Glutathione Transferase / Q000235:genetics / Q000378:metabolism*; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008168:Lung / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology; D009924:Organ Culture Techniques; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
D002274:Carcinogens, Environmental; D012333:RNA, Messenger; D001564:Benzo(a)pyrene; D001189:Aryl Hydrocarbon Hydroxylases; C585499:Cyp1b1 protein, rat; D019363:Cytochrome P-450 CYP1A1; D065633:Cytochrome P-450 CYP1B1; D005982:Glutathione Transferase; D004851:Epoxide Hydrolases