title: Effect of sublethal 6-hydroxydopamine on the response to subsequent oxidative stress in dopaminergic cells: evidence for preconditioning.
abstract: Exposure to sublethal stress can trigger endogenous protection against subsequent, higher levels of stress. We tested for this preconditioning phenomenon in a model of Parkinson's disease by applying 6-hydroxydopamine to the dopaminergic MN9D cell line. Exposure to sublethal concentrations of 6-hydroxydopamine (5-10 microM) protected against the toxic effects of a subsequent exposure to a higher concentration (50 microM), as measured by the Hoechst assay for nuclear viability. This was accompanied by little or no protection against 6-hydroxydopamine-induced lactate dehydrogenase release, decline in ATP, or reduction in (3)H-dopamine uptake. The antioxidant, N-acetyl cysteine (20 mM), when applied during preconditioning, abolished protection, as did the protein synthesis inhibitor, cycloheximide (0.2 microM). Preconditioning did not affect superoxide dismutase or glutathione peroxidase enzymes, or levels of heat shock protein-72. However, Bcl-2 protein levels rose with preconditioning. Preconditioning rapidly increased phosphorylation of kinases ERK1/2, Akt and JNK, and was abolished by pharmacological inhibitors of their activity. Finally, sublethal 6-hydroxydopamine preconditioned against the toxicity of proteasome inhibitor, MG-132 (1 microM). Thus, exposure of a dopaminergic cell line to sublethal oxidative stress can protect against additional oxidative stress due to translational and post-translational modifications, as well as confer 'cross-tolerance' against a different insult, proteasome inhibition.
authors.affiliation: Department of Neurology and Pittsburgh Institute of Neurodegenerative Disease, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA.
authors.forename: Rehana K
authors.initials: RK
authors.lastname: Leak
authors.forename: Anthony K F
authors.initials: AK
authors.lastname: Liou
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Zigmond
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D002460:Cell Line; D019610:Cytoprotection / Q000187:drug effects / Q000502:physiology*; D004298:Dopamine / Q000378:metabolism*; D004351:Drug Resistance / Q000502:physiology*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology; D051379:Mice; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology*; D016627:Oxidopamine / Q000633:toxicity; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D061988:Proteasome Inhibitors; D011499:Protein Processing, Post-Translational / Q000187:drug effects / Q000502:physiology; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D013378:Substantia Nigra / Q000187:drug effects / Q000378:metabolism* / Q000503:physiopathology; D013565:Sympatholytics / Q000633:toxicity
chemical_list: D000975:Antioxidants; D061988:Proteasome Inhibitors; D011500:Protein Synthesis Inhibitors; D013565:Sympatholytics; D016627:Oxidopamine; D000255:Adenosine Triphosphate; D007770:L-Lactate Dehydrogenase; D046988:Proteasome Endopeptidase Complex; D004298:Dopamine