Induction of hepatic heme oxygenase-1 by diclofenac in rodents: role of oxidative stress and cytochrome P-450 activity.
OBJECTIVE
The role of oxidative stress in diclofenac hepatotoxicity is still not clear. This study examined whether the drug induced heme oxygenase-1 (HO-1), a stress protein.


METHODS
HO-1 mRNA and HO activity were measured in mouse liver and in rat hepatocytes after treatment with diclofenac parallel to release of serum alanine aminotransferase (ALT) and sorbitol dehydrogenase (SDH) as a marker of hepatic damage.


RESULTS
HO-1 was transcriptionally and dose-dependently induced by diclofenac in mouse liver and rat hepatocytes. HO-1 mRNA, ALT and SDH peaked at the same time. Mechanistic studies revealed that the drug synergized with buthionine sulfoximine (BSO) in lowering hepatic glutathione, increased the formation of reactive oxygen intermediates and activated NF-kappaB and AP-1 in rat hepatocytes. HO-1 induction and hepatic damage were increased by BSO and only HO-1 induction was attenuated by the antioxidant N-acetylcysteine. HO-1 induction was also reduced by the cytochrome P-450 inhibitors ketoconazole and tranylcypromine, concomitantly with a significant decrease in the formation of diclofenac oxidative metabolites, which may give rise to reactive compounds.


CONCLUSIONS
Acute treatment with diclofenac induces HO-1 in rodent hepatocytes. Induction is influenced by changes in the cellular redox states and by cytochrome P-450 activity and gives a new insight into the response of the liver to diclofenac.
Cantoni
Lavinia
L
Laboratory of Molecular Pathology, Istituto di Ricerche Farmacologiche 'Mario Negri', Via Eritrea 62, 20157, Milan, Italy. cantoni@marionegri.it
Valaperta
Rea
R
Ponsoda
Xavier
X
Castell
José V
JV
Barelli
Davide
D
Rizzardini
Milena
M
Mangolini
Alessandra
A
Hauri
Lisa
L
Villa
Pia
P
D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D019328:Buthionine Sulfoximine / Q000494:pharmacology; D006528:Carcinoma, Hepatocellular / Q000201:enzymology / Q000473:pathology; D045744:Cell Line, Tumor; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D004008:Diclofenac / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004790:Enzyme Induction; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006419:Heme Oxygenase (Decyclizing) / Q000378:metabolism*; D051547:Heme Oxygenase-1; D022781:Hepatocytes / Q000201:enzymology; D006801:Humans; D008099:Liver / Q000201:enzymology*; D008113:Liver Neoplasms / Q000201:enzymology / Q000473:pathology; D008297:Male; D008565:Membrane Proteins; D051379:Mice; D008815:Mice, Inbred Strains; D018384:Oxidative Stress / Q000502:physiology*; D051381:Rats
D065607:Cytochrome P-450 Enzyme Inhibitors; D004791:Enzyme Inhibitors; D008565:Membrane Proteins; D004008:Diclofenac; D019328:Buthionine Sulfoximine; D003577:Cytochrome P-450 Enzyme System; C496541:HMOX1 protein, human; D006419:Heme Oxygenase (Decyclizing); D051547:Heme Oxygenase-1; C496542:Hmox1 protein, mouse; D000111:Acetylcysteine