Effects of valproate on xenobiotic biotransformation in rat liver |
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Authors: | V Rogiers A Callaerts A Vercruysse M Akrawi E Shephard and I Phillips |
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Institution: | (1) Department of Toxicology, Free University Brussels, Laarbeeklaan 103, 1090 Brussels, Belgium;(2) Department of Biochemistry and Molecular Biology, University College London, Gower Street, WC1E 6BT London, UK;(3) Department of Biochemistry, Queen Mary and Westfield College, University of London, Mile End Road, E1 4NS London, UK |
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Abstract: | Male Wistar rats werein vivo exposed for 2 weeks to 100 g/ml sodium valproate by subcutaneous implantation of osmotic pumps and hepatocytes were isolated. As anin vitro model co-cultures of rat hepatocytes with epithelial cells were daily treated with valproate (25, 50, 100, 200g/ml) for 2 weeks. In both models the cytochrome P-450 content and the enzymatic activities of 7-ethoxycoumarinO-deethylase, aldrin epoxidase and glutathioneS-transferase were determined in valproate-treated hepatocytes, in controls and in phenobarbital-induced cells. It appeared that in both systems the cytochrome P-450 content and the 7-ethoxycoumarinO-deethylase activity increased significantly after valproate treatment. On the other hand, the activities of aldrin epoxidase and glutathioneS-transferase decreased. A cDNA probe, encoding rat P450IIB2 was used to determine whether mRNAs encoding the P450IIB subfamily were induced by valproate. It became clear that the inducing effect of valproate was even more pronouncedin vitro thanin vivo. |
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Keywords: | Aldrin epoxidase 7-AlkoxycoumarinO-dealkylase Biotransformation Cytochrome P-450 Enzyme induction Glutathione transferases Hepatocytes Valproic acid |
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