title: Induction and recovery of hepatic drug metabolizing enzymes in rats treated with Ginkgo biloba extract.
abstract: Herb-drug interactions, especially cytochrome P450 (CYP)-mediated interactions, cause an enhancement or attenuation in efficacy of co-administered drugs. In a previous study, we reported that repeated oral ingestion of Ginkgo biloba extract (GBE) markedly induced hepatic drug metabolizing enzymes in rats. In this study, we focused on the recovery of GBE-induced hepatic drug metabolizing enzymes after the discontinuation of GBE in rats. Feeding of a 0.5% GBE diet to rats for 1 week markedly increased liver weight, content of total CYP, activities of 6 CYP subtypes and glutathione S-transferase (GST). The content and activities of CYP enzymes were recovered to almost basal levels within 1 week after the discontinuation of GBE, while the activity of GST gradually decreased and recovered to the control level after 3 weeks. These results indicated that GBE-induced hepatic drug metabolizing enzymes in rats, especially CYPs, were rapidly recovered by discontinuation of GBE in rats even after excess treatment, and suggested that interactions of GBE with drugs could be avoided by discontinuation of GBE.
authors.affiliation: National Institute of Health and Nutrition, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8636, Japan.
authors.forename: Tomomi
authors.initials: T
authors.lastname: Sugiyama
authors.forename: Yoko
authors.initials: Y
authors.lastname: Kubota
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Shinozuka
authors.forename: Shizuo
authors.initials: S
authors.lastname: Yamada
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Yamada
authors.forename: Keizo
authors.initials: K
authors.lastname: Umegaki
mesh_terms: D000818:Animals; D003577:Cytochrome P-450 Enzyme System / Q000187:drug effects* / Q000494:pharmacology*; D004347:Drug Interactions; D020441:Ginkgo biloba / Q000737:chemistry*; D005982:Glutathione Transferase / Q000187:drug effects* / Q000494:pharmacology*; D007700:Kinetics; D008099:Liver / Q000201:enzymology; D008297:Male; D010936:Plant Extracts / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar
chemical_list: D010936:Plant Extracts; D003577:Cytochrome P-450 Enzyme System; D005982:Glutathione Transferase