Specific combinations of ion channel inhibitors reduce excessive Ca2+ influx as a consequence of oxidative stress and increase neuronal and glial cell viability in vitro. (17th December 2016)

• Record Type: Journal Article
• Authors: O'Hare Doig, Ryan L.; Bartlett, Carole A.; Smith, Nicole M.; Hodgetts, Stuart I.; Dunlop, Sarah A.; Hool, Livia; Fitzgerald, Melinda
• Is Part Of: Neuroscience. Volume 339(2016)
• Page Start: 450
• Page End: 462
• Publication Date: 2016-12-17
• Subjects: AMPA α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid -- AMPARs α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors -- ANOVA analysis of variance -- ATP adenosine 5′-triphosphate -- Ca2+ calcium -- CNS central nervous system -- DMSO dimethyl sulfoxide -- EGTA ethylene glycol-bis(2-aminoethylether)-N, N, N′, N′-tetraacetic acid -- FOV field of view -- GFAP glial fibrillary acidic protein -- H hours -- HBSS Hanks balanced salt solution -- Lom Lomerizine -- MC mixed cortical -- Memantine (Mem) 3, 5-dimethyl-1-adamantanamine -- Min minutes -- NB Neurobasal® medium -- NMDA N-methyl-d-aspartate -- NMDARs N-methyl-d-aspartate receptors -- oxATP adenosine 5′-triphosphate periodate oxidized sodium salt -- P2X7R P2X7 receptors -- PBS phosphate buffered saline -- PFA paraformaldehyde -- PVG Piebald Viral Glaxo -- ROI region of interest -- SCI spinal cord injury -- SEM standard error of the mean -- TPEN N, N, N′, N′-Tetrakis(2-pyridylmethyl)ethylenediamine -- VGCCs voltage-gated Ca2+ channels -- YM872 2, 3-dioxo-7-(1H-imidazol-1-yl)6-nitro-1, 2, 3, 4-tetrahydro-1-quinoxalinyl]acetic acid monohydrate; Ca2+ channel inhibitors -- intracellular Ca2+ concentration -- oligodendroglia -- NG2-glia -- Cell viability; Neurochemistry -- Periodicals; Neurophysiology -- Periodicals; Neurology -- Periodicals; Neurochimie -- Périodiques; Neurophysiologie -- Périodiques; Neurochemistry; Neurophysiology; Electronic journals; Periodicals; Electronic journals; 612.8
• DOI: 10.1016/j.neuroscience.2016.10.005
• Languages: English
• ISSNs: 0306-4522

Abstract

Highlights: The effects of combinations of ion channel inhibitors on H2 O2 stressed cells were assessed in vitro . Most combinations of inhibitors with oxATP decreased Ca 2+ influx and increased cell viability. However, reductions in intracellular Ca 2+ concentration were not always linked to cell viability. Combinations of inhibitors preserved some cell subpopulations, particularly NG2+/olig2− glia. The data increase understanding of the efficacy of ion channel inhibitor combinations in vivo . Abstract: Combinations of Ca 2+ channel inhibitors have been proposed as an effective means to prevent excess Ca 2+ flux and death of neurons and glia following neurotrauma in vivo . However, it is not yet known if beneficial outcomes such as improved viability have been due to direct effects on intracellular Ca 2+ concentrations. Here, the effects of combinations of Lomerizine (Lom), 2, 3-dioxo-7-(1 H -imidazol-1-yl)6-nitro-1, 2, 3, 4-tetrahydro-1-quinoxalinyl]acetic acid monohydrate (YM872), 3, 5-dimethyl-1-adamantanamine (memantine (Mem)) and/or adenosine 5′-triphosphate periodate oxidized sodium salt (oxATP) to block voltage-gated Ca 2+ channels, Ca 2+ permeable α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors, NMDA receptors and purinergic P2X7 receptors (P2X7 R) respectively, on Ca 2+ concentration and viability of rat primary mixed cortical (MC) cultures exposed to hydrogen peroxide (H2 O2 ) insult, were assessed. The contribution of ryanodine-sensitive intracellular stores to intracellular Ca 2+ concentration was also assessed. Live cell calcium imaging revealed that a 30 min H2 O2 insult induced a slow increase in intracellular Ca 2+, in part from intracellular sources, associated with loss of cell viability by 6 h. Most combinations of inhibitors that included oxATP significantly decreased Ca 2+ influx and increased cell viability when administered simultaneously with H2 O2 . However, reductions in intracellular Ca 2+ concentration were not always linked to improved cell viability. Examination of the density of specific cell subpopulations demonstrated that most combinations of inhibitors that included oxATP preserved NG2+ non-oligodendroglial cells, but preservation of astrocytes and neurons required additional inhibitors. Olig2 + oligodendroglia and ED-1 + activated microglia/macrophages were not preserved by any of the inhibitor combinations. These data indicate that following H2 O2 insult, limiting intracellular Ca 2+ entry via P2X7 R is generally associated with increased cell viability. Protection of NG2+ non-oligodendroglial cells by Ca 2+ channel inhibitor combinations may contribute to observed beneficial outcomes in vivo .