title: Insensitivity to glutamate neurotoxicity mediated by NMDA receptors in association with delayed mitochondrial membrane potential disruption in cultured rat cortical neurons.
abstract: We have attempted to elucidate mechanisms underlying differential vulnerability to glutamate (Glu) using cultured neurons prepared from discrete structures of embryonic rat brains. Brief exposure to Glu led to a significant decrease in the mitochondrial activity in hippocampal neurons cultured for 9 or 12 days at 10 muM to 1 mM with an apoptosis-like profile, without markedly affecting that in cortical neurons. Brief exposure to Glu also increased lactate dehydrogenase release along with a marked decrease in the number of cells immunoreactive for a neuronal marker protein in hippocampal, but not cortical, neurons. Similar insensitivity was seen to the cytotoxicity by NMDA, but not to that by tunicamycin, 2,4-dinitrophenol, hydrogen peroxide or A23187, in cortical neurons. However, NMDA was more efficient in increasing intracellular free Ca2+ levels in cortical neurons than in hippocampal neurons. Antagonists for neuroprotective metabotropic Glu receptors failed to significantly affect the insensitivity to Glu, while NMDA was more effective in disrupting mitochondrial membrane potentials in hippocampal than cortical neurons. These results suggest that cortical neurons would be insensitive to the apoptotic neurotoxicity mediated by NMDA receptors through a mechanism related to mitochondrial membrane potentials, rather than intracellular free Ca2+ levels, in the rat brain.
authors.affiliation: Laboratory of Molecular Pharmacology, Division of Pharmaceutical Sciences, Kanazawa University Graduate School of Natural Science and Technology, Kanazawa, Ishikawa, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Kambe
authors.forename: Noritaka
authors.initials: N
authors.lastname: Nakamichi
authors.forename: Danko D
authors.initials: DD
authors.lastname: Georgiev
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Nakamura
authors.forename: Hideo
authors.initials: H
authors.lastname: Taniura
authors.forename: Yukio
authors.initials: Y
authors.lastname: Yoneda
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000187:drug effects / Q000502:physiology*; D018698:Glutamic Acid / Q000633:toxicity*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology*; D051336:Mitochondrial Membranes / Q000187:drug effects / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000819:agonists / Q000502:physiology*; D013997:Time Factors
chemical_list: D016194:Receptors, N-Methyl-D-Aspartate; D018698:Glutamic Acid