title: Peroxynitrite-mediated oxidative damage to brain mitochondria: Protective effects of peroxynitrite scavengers.
abstract: Peroxynitrite-mediated oxidative damage has been implicated in brain mitochondrial respiratory dysfunction after traumatic brain injury (TBI), which precedes the onset of neuronal loss. The aim of this study was to investigate the detrimental effects of the peroxynitrite donor SIN-1 (3-morpholinosydnonimine) on isolated brain mitochondria and to screen penicillamine, a stoichiometric (1:1) peroxynitrite-scavenging agent, and tempol, a catalytic scavenger of peroxynitrite-derived radicals, as antioxidant mitochondrial protectants. Exposure of the isolated mitochondria to SIN-1 caused a significant dose-dependent decrease in the respiratory control ratio and was accompanied by a significant increase in state II respiration, followed by significant decreases (P < 0.05) in states III and V. These functional alterations occurred together with significant increases in mitochondrial protein carbonyl (PC), lipid peroxidation-related 4-hydroxynonenal (4-HNE), and 3-nitrotyrosine (3-NT) content. Penicillamine hydrochloride (10 microM) partially but significantly (P < 0.05) protected against SIN-1-induced decreases in states III and V. However, a 2.5 microM concentration of tempol was able to significantly antagonize a 4-fold molar excess (10 microM) concentration of SIN-1 as effectively as were higher tempol concentrations, consistent with the likelihood that tempol works by a catalytic mechanism. The protection of mitochondrial respiration by penicillamine and tempol occurred in parallel with attenuation of PC, 4-HNE, and 3-NT. These results indicate that SIN-1 causes mitochondrial oxidative damage and complex I dysfunction and that antioxidant compounds that target either peroxynitrite or its radicals may be effective mitochondrial protectants in the treatment of neural injury.
authors.affiliation: Spinal Cord & Brain Injury Research Center, University of Kentucky College of Medicine, Lexington, KY 40536-0509, USA.
authors.forename: Indrapal N
authors.initials: IN
authors.lastname: Singh
authors.forename: Patrick G
authors.initials: PG
authors.lastname: Sullivan
authors.forename: Edward D
authors.initials: ED
authors.lastname: Hall
mesh_terms: D000447:Aldehydes / Q000037:antagonists & inhibitors; D000818:Animals; D019069:Cell Respiration / Q000187:drug effects; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism*; D003497:Cyclic N-Oxides / Q000008:administration & dosage / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D042967:Electron Transport Complex I / Q000187:drug effects / Q000502:physiology; D016166:Free Radical Scavengers / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D008981:Molsidomine / Q000031:analogs & derivatives / Q000494:pharmacology; D020030:Nitric Oxide Donors / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects; D010101:Oxygen Consumption / Q000187:drug effects; D010396:Penicillamine / Q000008:administration & dosage / Q000494:pharmacology; D030421:Peroxynitrous Acid / Q000037:antagonists & inhibitors* / Q000494:pharmacology*; D050050:Protein Carbonylation / Q000187:drug effects; D013113:Spin Labels; D014443:Tyrosine / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors
chemical_list: D000447:Aldehydes; D003497:Cyclic N-Oxides; D016166:Free Radical Scavengers; D020030:Nitric Oxide Donors; D013113:Spin Labels; D030421:Peroxynitrous Acid; C002744:3-nitrotyrosine; D014443:Tyrosine; C002385:linsidomine; D008981:Molsidomine; D042967:Electron Transport Complex I; D010396:Penicillamine; C027576:4-hydroxy-2-nonenal; C001803:tempol