title: Up-regulation of P-glycoprotein expression by glutathione depletion-induced oxidative stress in rat brain microvessel endothelial cells.
abstract: Glutathione (GSH) depletion has been implicated in the pathogenesis of neurological diseases. During GSH depletion, cells of the blood-brain barrier (BBB) are subjected to chronic oxidative stress. In this study, we investigated the effect of such stress, produced with the GSH synthesis inhibitor l-buthionine-(S,R)-sulfoximine (BSO), on expression of P-glycoprotein (Pgp) in primary cultured rat brain microvessel endothelial cells that comprise the blood-brain barrier (BBB). Application of BSO to cell monolayers at concentrations up to 800 microm caused increases in expression of Pgp. Concentrations >or= 400 microm BSO decreased cell viability. Application of 200 microm BSO caused a significant increase in Pgp function activity, as assessed by rhodamine 123 (Rh123) accumulation experiments. At this concentration, BSO produced time-dependent decreases in levels of intracellular GSH and increases in levels of intracellular reactive oxygen species (iROS). The increases were also observed within 48 h following BSO treatment in mdr1a and mdr1b mRNA. Exposure of cells to BSO for 24 h produced maximal effects in the accumulation of iROS, and in expression and function of Pgp. The ROS scavenger N-acetylcysteine prevented ROS generation and attenuated the changes of both expression and activity of Pgp induced by BSO. Therefore, the transport of Pgp substrates may be affected by changing Pgp expression under conditions of chronic oxidative stress induced by GSH depletion.
authors.affiliation: Department of Pharmacology, China Pharmaceutical University, Nanjing, China. haohongchina@hotmail.com
authors.forename: Hao
authors.initials: H
authors.lastname: Hong
authors.forename: Ying
authors.initials: Y
authors.lastname: Lu
authors.forename: Zhao-Ning
authors.initials: ZN
authors.lastname: Ji
authors.forename: Guo-Qing
authors.initials: GQ
authors.lastname: Liu
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B / Q000235:genetics / Q000378:metabolism*; D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D015153:Blotting, Western / Q000379:methods; D001921:Brain / Q000166:cytology*; D019328:Buthionine Sulfoximine / Q000494:pharmacology; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions / Q000502:physiology; D042783:Endothelial Cells / Q000187:drug effects / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016166:Free Radical Scavengers / Q000494:pharmacology; D005978:Glutathione / Q000172:deficiency*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D020112:Rhodamine 123; D013778:Tetrazolium Salts; D013844:Thiazoles; D013997:Time Factors; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D018435:ATP Binding Cassette Transporter, Subfamily B; D004791:Enzyme Inhibitors; D016166:Free Radical Scavengers; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D013778:Tetrazolium Salts; D013844:Thiazoles; D020112:Rhodamine 123; D019328:Buthionine Sulfoximine; D007770:L-Lactate Dehydrogenase; C022616:thiazolyl blue; D005978:Glutathione; D000111:Acetylcysteine