Temporal evaluation of CYP mRNA in mice administered with prototypical P450 inducers: comparison with conventional protein/enzyme methods.
Assessment of cytochrome P450 (CYP) induction at the mRNA level in preclinical rodent studies has gained interest in recent years, but there are still concerns regarding correlations between the mRNA and the enzyme activity levels, especially in mice. The purpose of the present study was to systematically evaluate patterns of temporal changes of CYPs 1a1, 1a2, 2b10, 3a11, and 4a10 at mRNA, protein, and activity levels in order to determine to what extent mRNA levels could be used either qualitatively or quantitatively for the assessment of CYP enzyme induction. In this study, livers from male CD-1 mice treated daily with beta-naphthoflavone, phenobarbital, dexamethasone, clofibrate, and control vehicles were collected for RNA and microsomal analysis after 0.5, 1, 2, 4, and 8 days of daily dose. The results revealed a good correlation among mRNA, protein, and enzyme activity levels, with the best correlation at the time points between Days 2 and 8, suggesting that the appropriate time to monitor CYP mRNA may be beyond Day 2 of chemical treatments. Based on these results, we concluded that the mRNA approach is a useful tool to monitor CYP induction in mice, particularly when treatment duration is beyond 2 days.
Wang
Er-Jia
EJ
Department of Genetic and Molecular Toxicology, Schering-Plough Corporation, Summit, New Jersey 07901, USA. erjia.wang@spcorp.com
Mandakas
George
G
Palamanda
Jairam
J
Lin
Xinjie
X
Kumari
Pramila
P
Chu
Inhou
I
Soares
Anthony
A
Smith
Roger J
RJ
Snyder
Ronald D
RD
Gu
Yi-Zhong
YZ
D000818:Animals; D002994:Clofibrate / Q000494:pharmacology; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis* / Q000235:genetics; D003907:Dexamethasone / Q000494:pharmacology; D004353:Drug Evaluation, Preclinical / Q000379:methods*; D004790:Enzyme Induction / Q000187:drug effects; D005240:Feasibility Studies; D007527:Isoenzymes; D008099:Liver / Q000187:drug effects* / Q000201:enzymology; D008297:Male; D051379:Mice; D010634:Phenobarbital / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis*; D015203:Reproducibility of Results; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D019324:beta-Naphthoflavone / Q000494:pharmacology
D007527:Isoenzymes; D012333:RNA, Messenger; D019324:beta-Naphthoflavone; D003907:Dexamethasone; D003577:Cytochrome P-450 Enzyme System; D002994:Clofibrate; D010634:Phenobarbital