title: Hepatic effects of repeated oral administration of diclofenac to hepatic cytochrome P450 reductase null (HRN™) and wild-type mice.
abstract: Hepatic NADPH-cytochrome P450 oxidoreductase null (HRN™) mice exhibit normal hepatic and extrahepatic biotransformation enzyme activities when compared to wild-type (WT) mice, but express no functional hepatic cytochrome P450 activities. When incubated in vitro with [(14)C]-diclofenac, liver microsomes from WT mice exhibited extensive biotransformation to oxidative and glucuronide metabolites and covalent binding to proteins was also observed. In contrast, whereas glucuronide conjugates and a quinone-imine metabolite were formed when [(14)C]-diclofenac was incubated with HRN™ mouse liver, only small quantities of P450-derived oxidative metabolites were produced in these samples and covalent binding to proteins was not observed. Livers from vehicle-treated HRN™ mice exhibited enhanced lipid accumulation, bile duct proliferation, hepatocellular degeneration and necrosis and inflammatory cell infiltration, which were not present in livers from WT mice. Elevated liver-derived alanine aminotransferase, glutamate dehydrogenase and alkaline phosphatase activities were also observed in plasma from HRN™ mice. When treated orally with diclofenac for 7 days, at 30 mg/kg/day, the severities of the abnormal liver histopathology and plasma liver enzyme findings in HRN™ mice were reduced markedly. Oral diclofenac administration did not alter the liver histopathology or elevate plasma enzyme activities of WT mice. These findings indicate that HRN™ mice are valuable for exploration of the role played by hepatic P450s in drug biotransformation, but poorly suited to investigations of drug-induced liver toxicity. Nevertheless, studies in HRN™ mice could provide novel insights into the role played by inflammation in liver injury and may aid the evaluation of new strategies for its treatment.
authors.affiliation: MRC Centre for Drug Safety Science, University of Liverpool, Liverpool, L69 3GE, UK. j.akingbasote@liverpool.ac.uk.|Department of Pharmacology, Faculty of Pharmacy, Obafemi Awolowo University, Ile-Ife, 220005, Osun State, Nigeria. j.akingbasote@liverpool.ac.uk.
authors.forename: James A
authors.initials: JA
authors.lastname: Akingbasote
authors.affiliation: Translational Safety, Drug Safety and Metabolism, AstraZeneca, Alderley Park, Macclesfield, Cheshire, SK10 4TG, UK. alison.foster2@astrazeneca.com.
authors.forename: Alison J
authors.initials: AJ
authors.lastname: Foster
authors.affiliation: Section of Computational and Systems Medicine, Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK. iwilson@imperial.ac.uk.
authors.forename: Ian
authors.initials: I
authors.lastname: Wilson
authors.affiliation: Discovery Sciences, AstraZeneca, Alderley Park, Macclesfield, Cheshire, SK10 4TG, UK. sunil.sarda@astrazeneca.com.
authors.forename: Sunil
authors.initials: S
authors.lastname: Sarda
authors.affiliation: Translational Safety, Drug Safety and Metabolism, AstraZeneca, Alderley Park, Macclesfield, Cheshire, SK10 4TG, UK. huwbjoneshb@gmail.com.
authors.forename: Huw B
authors.initials: HB
authors.lastname: Jones
authors.affiliation: FRAME, Nottingham, UK. jgerrykenna@gmail.com.
authors.forename: J Gerry
authors.initials: JG
authors.lastname: Kenna
mesh_terms: D000284:Administration, Oral; D000818:Animals; D001711:Biotransformation; D056486:Chemical and Drug Induced Liver Injury / Q000209:etiology; D004008:Diclofenac / Q000008:administration & dosage* / Q000009:adverse effects* / Q000493:pharmacokinetics / Q000652:urine; D008099:Liver / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D008297:Male; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology; D009251:NADPH-Ferrihemoprotein Reductase / Q000235:genetics / Q000378:metabolism*
chemical_list: D004008:Diclofenac; D009251:NADPH-Ferrihemoprotein Reductase
keywords: Biotransformation; Covalent binding; Diclofenac; Intestinal toxicity; Liver effects