title: Glutathione-mediated neuroprotection against methylmercury neurotoxicity in cortical culture is dependent on MRP1.
abstract: Methylmercury (MeHg) exposure at high concentrations poses significant neurotoxic threat to humans worldwide. The present study investigated the mechanisms of glutathione-mediated attenuation of MeHg neurotoxicity in primary cortical culture. MeHg (5 μM) caused depletion of mono- and disulfide glutathione in neuronal, glial and mixed cultures. Supplementation with exogenous glutathione, specifically glutathione monoethyl ester (GSHME) protected against the MeHg induced neuronal death. MeHg caused increased reactive oxygen species (ROS) formation measured by dichlorodihydrofluorescein (DCF) fluorescence with an early increase at 30 min and a late increase at 6h. This oxidative stress was prevented by the presence of either GSHME or the free radical scavenger, trolox. While trolox was capable of quenching the ROS, it showed no neuroprotection. Exposure to MeHg at subtoxic concentrations (3 μM) caused an increase in system x(c)(-) mediated (14)C-cystine uptake that was blocked by the protein synthesis inhibitor, cycloheximide (CHX). Interestingly, blockade of the early ROS burst prevented the functional upregulation of system x(c)(-). Inhibition of multidrug resistance protein-1 (MRP1) potentiated MeHg neurotoxicity and increased cellular MeHg. Taken together, these data suggest glutathione offers neuroprotection against MeHg toxicity in a manner dependent on MRP1-mediated efflux.
authors.affiliation: Department of Biomedical Sciences, Marquette University, Milwaukee, WI 53233, USA.
authors.forename: Travis
authors.initials: T
authors.lastname: Rush
authors.forename: XiaoQian
authors.initials: X
authors.lastname: Liu
authors.forename: Andrew B
authors.initials: AB
authors.lastname: Nowakowski
authors.forename: David H
authors.initials: DH
authors.lastname: Petering
authors.forename: Doug
authors.initials: D
authors.lastname: Lobner
mesh_terms: D027182:Amino Acid Transport System y+ / Q000378:metabolism; D000818:Animals; D016923:Cell Death / Q000187:drug effects; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000187:drug effects* / Q000196:embryology / Q000378:metabolism / Q000473:pathology; D003553:Cystine / Q000378:metabolism; D019610:Cytoprotection; D004305:Dose-Response Relationship, Drug; D005260:Female; D016166:Free Radical Scavengers / Q000494:pharmacology; D005978:Glutathione / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D020262:Mercury Poisoning, Nervous System / Q000209:etiology / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D008767:Methylmercury Compounds / Q000378:metabolism / Q000633:toxicity*; D051379:Mice; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018696:Neuroprotective Agents / Q000378:metabolism / Q000494:pharmacology*; D018384:Oxidative Stress / Q000187:drug effects; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism; D013997:Time Factors
chemical_list: D027182:Amino Acid Transport System y+; D003553:Cystine; D016166:Free Radical Scavengers; D005978:Glutathione; D008767:Methylmercury Compounds; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D018696:Neuroprotective Agents; D011500:Protein Synthesis Inhibitors; D017382:Reactive Oxygen Species; C492255:Slc7a11 protein, mouse; C042431:S-ethyl glutathione; C421109:multidrug resistance-associated protein 1