Title
Characterization of cytochrome P450 isoenzymes in primary cultures of pig hepatocytes
Author
Monshouwer, M.
van 't Klooster, G.A.E.
Nijmeijer, S.M.
Witkamp, R.F.
van Miert, A.S.J.P.A.M.
Centraal Instituut voor Voedingsonderzoek TNO
Publication year
1998
Abstract
Despite the fact that pigs are increasingly used in pharmacological and toxicological studies, knowledge on the enzymes which metabolize xenobiotics, in particular cytochrome P450 (CYP) enzymes, in pigs is still very limited. Primary cultures of pig hepatocytes were used to characterize CYP enzymes. The characterization was performed at the level of enzymatic activities, apoprotein and mRNA analyses. Enzyme inducers investigated were β- naphthoflavone (BNF), phenobarbital (PB), dexamethasone (DEX) and rifampicin (RIF). After 48 hr of BNF treatment, CYP1A protein and mRNA levels were increased, and ethoxyresorufin O-deethylation and caffeine 3-demethylation were strongly induced. PB and RIF increased the levels of CYP3A apoprotein and mRNA, whereas BNF down-regulated CYP3A and related activities. PB and RIF treatment resulted in increased ethylmorphine N-demethylation and testosterone hydroxylation, which appears to be the result of CYP3A induction. Hybridization of pig RNA with a human CYP2C9 cDNA probe showed a PB and RIF inducible CYP, which was down-regulated by BNF. Similar inducing effects were observed for tolbutamide, a marker substrate for CYP2C. DEX was not a potent inducer, although some induction of CYP3A mRNA was observed. The present results indicate the absence of CYP2B and probably CYP2D enzymes and activities in pig liver. Despite some dissimilarities, the results indicate that pigs, apart from their very human-like physiology, might represent a more appropriate model species for oxidative drug metabolism in humans than rats.
Subject
Nutrition
Cytochrome P450
Hepatocytes
Induction
Pig
Apoprotein
Beta naphthoflavone
Complementary DNA
Cytochrome p450 isoenzyme
Dexamethasone
Ethoxyresorufin deethylase
Ethylmorphine n demethylase
Messenger RNA
Oxygenase
Phenobarbital
Rifampicin
Animal cell
Controlled study
Enzyme activity
Enzyme analysis
Enzyme induction
Liver cell culture
Nonhuman
RNA analysis
RNA hybridization
Swine
Xenobiotic metabolism
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http://resolver.tudelft.nl/uuid:c4437ffb-5bde-4f27-9a2d-a67721a04612
DOI
https://doi.org/10.1016/s0887-2333(98)00053-8
TNO identifier
234842
ISSN
0887-2333
Source
Toxicology in Vitro, 12 (6), 715-723
Document type
article