title: Nitric-oxide-induced depolarization of neuronal mitochondria: implications for neuronal cell death.
abstract: Nitric oxide (NO(*)) has known toxic effects on central nervous system neurons. This study characterized the effect of NO(*) on mitochondrial membrane changes by exploring the relationship among NO(*), excitatory receptor activation, and the induction of peroxynitrite, a highly toxic NO(*) reactant, to neuronal injury. Cultured rat cortical neurons were exposed to the NO(*) generator, diethylenetriamine/nitric oxide adduct, and were examined for signs of cell death, mitochondrial membrane potential changes (Deltapsi(m)), and the induction of a mitochondrial permeability transition (MPT). Neurons were also examined for nitrotyrosine (NT) immunoreactivity, a marker of reactive nitrogen species (RNS) formation. Neurons exposed to NO(*) or to N-methyl-D-aspartate (NMDA) exhibited similar rapid depolarization of mitochondria, which was prevented by an NMDA receptor antagonist. Electrophysiological studies demonstrated NO(*) potentiation of NMDA-induced NMDA receptor currents. NO(*) and NMDA-treated neurons had evidence of mitochondrial-specific NT immunoreactivity that was prevented by a SOD/catalase mimetic (EUK-134). EUK-134 treatment reduced both NO(*) and NMDA-induced NT formation and neuronal cell death. EUK-134 did not prevent NO-induced Deltapsi(m) but partially prevented NMDA-induced Deltapsi(m) loss. Although NO(*) and NMDA both induced MPT and MPT inhibitors prevented NO-induced Deltapsi(m), they did not result in significant neuroprotection, in contrast to treatment designed to decrease peroxynitrite formation. These data suggest that NO-induced NMDA receptor activation is closely linked to intramitochondrial NO-peroxynitrite/RNS formation and thereby acts as a major mediator of neuronal cell death.
authors.affiliation: Department of Neurology, University of Virginia Health Sciences System, Charlottesville, VA 22908, USA. njs2j@virginia.edu
authors.forename: Nina J
authors.initials: NJ
authors.lastname: Solenski
authors.forename: Vannessa K
authors.initials: VK
authors.lastname: Kostecki
authors.forename: Serena
authors.initials: S
authors.lastname: Dovey
authors.forename: Ammasi
authors.initials: A
authors.lastname: Periasamy
mesh_terms: D000818:Animals; D016923:Cell Death / Q000502:physiology; D002478:Cells, Cultured; D008928:Mitochondria / Q000187:drug effects* / Q000502:physiology; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D009569:Nitric Oxide / Q000633:toxicity*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D009569:Nitric Oxide