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Arutjunyan AV, Evsyukova II, Polyakova VO. The Role of Melatonin in Morphofunctional Development of the Brain in Early Ontogeny. NEUROCHEM J+ 2019. [DOI: 10.1134/s1819712419030036] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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2
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Samaiya PK, Narayan G, Kumar A, Krishnamurthy S. Tempol (4 hydroxy-tempo) inhibits anoxia-induced progression of mitochondrial dysfunction and associated neurobehavioral impairment in neonatal rats. J Neurol Sci 2017; 375:58-67. [DOI: 10.1016/j.jns.2017.01.021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 12/20/2016] [Accepted: 01/06/2017] [Indexed: 10/20/2022]
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3
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Coumans ABC, Garnier Y, Supçun S, Jensen A, Hasaart THM, Berger R. The Role of Nitric Oxide on Fetal Cardiovascular Control During Normoxia and Acute Hypoxia in 0.75 Gestation Sheep. ACTA ACUST UNITED AC 2016. [DOI: 10.1016/s1071-55760300085-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
| | | | | | - A. Jensen
- Department of Obstetrics and Gynecology, University of Maastricht, Maastricht, The Netherlands, and Department of Obstetrics and Gynecology, University of Bochum, Bochum, Germany
| | - T. H. M. Hasaart
- Department of Obstetrics and Gynecology, University of Maastricht, Maastricht, The Netherlands, and Department of Obstetrics and Gynecology, University of Bochum, Bochum, Germany; University Hospital Maastricht, PO Box 5800, P. Debyelaan 25, 6202 AZ Maastricht, The Netherlands
| | - R. Berger
- Department of Obstetrics and Gynecology, University of Maastricht, Maastricht, The Netherlands, and Department of Obstetrics and Gynecology, University of Bochum, Bochum, Germany
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4
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Characterization of mitochondrial bioenergetics in neonatal anoxic model of rats. J Bioenerg Biomembr 2015; 47:217-22. [PMID: 25637096 DOI: 10.1007/s10863-015-9603-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2014] [Accepted: 01/19/2015] [Indexed: 12/11/2022]
Abstract
Neonatal anoxia at the time of birth can lead to mitochondrial dysfunction and further neurodevelopmental abnormalities. The present study investigated the mitochondrial bioenergetics and associated sensorimotor changes in the anoxic neonatal rats. Rat pups after 30 h to birth (2 days) were subjected to anoxia of two episodes (10 min in each) at a time interval of 24 h by passing 100 % N2 into an enclosed chamber. Brain mitochondrial respiration was measured using clark type oxygen electrode. A significant decrease in brain respiratory control ratio (RCR; State III/IV respiration) at all-time points, complex I (24 h) and complex II (30 min, 6 and 24 h) enzyme activities indicated loss of mitochondrial integrity and function A significant increase in levels of nitric oxide was observed after second anoxic episode at all-time points. A significant change in sensorimotor activity in terms of increased reflex latency was observed 24 h after second episode in this model, which is an indication of loss of subcortical maturation. All the above changes were observed after second but not after the first anoxic exposure. Therefore, this anoxic model shows significant changes in mitochondrial bioenergetics, nitric oxide levels and sensorimotor effects after second episode of anoxia. This model may be helpful to evaluate mitochondrial targeted pharmacological intervention for the treatment of anoxia.
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5
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Muller AJ, Marks JD. Hypoxic ischemic brain injury: Potential therapeutic interventions for the future. Neoreviews 2014; 15:e177-e186. [PMID: 25177211 DOI: 10.1542/neo.15-5-e177] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Perinatal hypoxic-ischemic brain injury is a common problem with potentially devastating impact on neurodevelopmental outcomes. While therapeutic hypothermia, the first available treatment for this disease, reduces the risk of death or major neurodevelopmental disability, the risk of major neurologic morbidity following HI remains significant. Basic research has identified cellular mechanisms that mediate neuronal death. This article reviews the cellular processes induced that lead to brain injury following HI, and identify treatments currently under investigation for potential translation to clinical trials.
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Affiliation(s)
- Aaron J Muller
- Department of Pediatrics, University of Chicago 900 East 57th Street Chicago IL 60637
| | - Jeremy D Marks
- Department of Neurology, University of Chicago 900 East 57th Street Chicago IL 60637
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Wang S, Qian Y, Gong D, Zhang Y, Fan Y. Resveratrol attenuates acute hypoxic injury in cardiomyocytes: Correlation with inhibition of iNOS–NO signaling pathway. Eur J Pharm Sci 2011; 44:416-21. [DOI: 10.1016/j.ejps.2011.08.029] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Revised: 08/09/2011] [Accepted: 08/30/2011] [Indexed: 01/06/2023]
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7
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Wu PY, Lai B, Dong Y, Wang ZM, Li ZC, Zheng P. Different oxidants and PKC isozymes mediate the opposite effect of inhibition of Qi and Qo site of mitochondrial complex III on calcium currents in rat cortical neurons. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1803:1072-82. [DOI: 10.1016/j.bbamcr.2010.05.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2010] [Revised: 04/29/2010] [Accepted: 05/03/2010] [Indexed: 10/19/2022]
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8
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Nitric oxide alters GABAergic synaptic transmission in cultured hippocampal neurons. Brain Res 2009; 1297:23-31. [PMID: 19699726 DOI: 10.1016/j.brainres.2009.08.044] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2009] [Revised: 08/11/2009] [Accepted: 08/13/2009] [Indexed: 01/23/2023]
Abstract
Nitric oxide (NO) production increases during hypoxia/ischemia-reperfusion in the immature brain and is associated with neurotoxicity. NO at physiologic concentrations has been shown to modulate GABAergic (gamma-aminobutyric acid) synaptic transmission in the adult brain. However, the effects of neurotoxic concentrations of NO (relevant to hypoxia-ischemia) on GABAergic synaptic transmission remain unknown. The present study tests the hypothesis that nNOS is expressed at GABAergic synapses and that exposure to neurotoxic concentrations of NO results in enhanced GABAergic synaptic transmission in cultured hippocampal neurons (days-in-vitro 10-14) prepared from fetal rats. Using double immunocytochemistry techniques, we were able to demonstrate that nNOS is co-localized to both presynaptic and postsynaptic markers of GABAergic synapses. The effects of NO on GABAergic synaptic transmission were then studied using whole cell patch-clamp electrophysiology. Spontaneous and miniature inhibitory postsynaptic currents (sIPSCS and mIPSCs) were recorded prior to and after exposure to 250 microM of the NO donor diethyleneamine/nitric oxide adduct (DETA-NO). Exposure to DETA-NO resulted in increased sIPSCs and mIPSCs frequency, indicating that neurotoxic concentrations of NO enhance GABAergic synaptic transmission in cultured hippocampal neurons. Because GABA synapses appear to be excitatory in the immature brain, this effect may contribute to overall enhanced synaptic transmission and hyperexcitability. We speculate that NO represents one of the mechanisms by which hypoxia-ischemia increases seizure susceptibility in the immature brain.
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9
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Sumbayev VV, Yasinska IM. Mechanisms of hypoxic signal transduction regulated by reactive nitrogen species. Scand J Immunol 2007; 65:399-406. [PMID: 17444949 DOI: 10.1111/j.1365-3083.2007.01919.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Recent reports devoted to the field of oxygen sensing outline that signalling molecules such as nitric oxide/nitric oxide derived species as well as cytokines and other inflammatory mediators participate in hypoxic signal transduction. In the present review, we summarize the current knowledge about the role of nitric oxide and reactive nitrogen species (RNS) derived from it in hypoxic signal transduction and particularly in accumulation/de-accumulation of hypoxia inducible factor 1 alpha (HIF-1alpha) protein, which is critical not only for cellular adaptation to low oxygen availability but also for generation of inflammatory and innate immune responses. After brief description of nitric oxide and other RNS as multifunctional messengers we analyse and discuss the RNS-dependent accumulation of HIF-1alpha protein under normoxia followed by discussion of the mechanisms of nitric oxide (NO)-dependent enzyme-regulated degradation of HIF-1alpha protein under low oxygen availability.
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Affiliation(s)
- V V Sumbayev
- Medway School of Pharmacy, University of Kent and Greenwich, Kent, UK.
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10
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Klawitter V, Morales P, Bustamante D, Goiny M, Herrera-Marschitz M. Plasticity of the central nervous system (CNS) following perinatal asphyxia: does nicotinamide provide neuroprotection? Amino Acids 2006; 31:377-84. [PMID: 16871361 DOI: 10.1007/s00726-006-0372-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2005] [Accepted: 03/08/2006] [Indexed: 12/01/2022]
Abstract
We have investigated the idea that nicotinamide, a non-selective inhibitor of the sentinel enzyme Poly(ADP-ribose) polymerase-I (PARP-1), provides neuroprotection against the long-term neurological changes induced by perinatal asphyxia. Perinatal asphyxia was induced in vivo by immersing foetuses-containing uterine horns removed from ready-to-deliver rats into a water bath for 20 min. Sibling caesarean-delivered pups were used as controls. The effect of perinatal asphyxia on neurocircuitry development was studied in vitro with organotypic cultures from substantia nigra, neostriatum and neocortex, platted on a coverslip 3 days after birth. After approximately one month in vitro (DIV 25), the cultures were treated for immunocytochemistry to characterise neuronal phenotype with markers against the N-methyl-D-aspartate receptor subunit 1 (NR1), the dopamine pacemaker enzyme tyrosine hydroxylase (TH), and nitric oxide synthase (NOS), the enzyme regulating the bioavailability of NO. Nicotinamide (0.8 mmol/kg, i.p.) or saline was administered to asphyctic and caesarean-delivered pups 24, 48 and 72 h after birth. It was found that nicotinamide treatment prevented the effect of perinatal asphyxia on several neuronal parameters, including TH- and NOS-positive neurite atrophy and NOS-positive neuronal loss; supporting the idea that nicotinamide constitutes a therapeutic alternative for the effects produced by sustained energy-failure conditions, as occurring during perinatal asphyxia.
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Affiliation(s)
- V Klawitter
- Programme of Molecular and Clinical Pharmacology, ICBM, Medical Faculty, University of Chile, Santiago, Chile
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11
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Zanelli SA, Trimmer PA, Solenski NJ. Nitric oxide impairs mitochondrial movement in cortical neurons during hypoxia. J Neurochem 2006; 97:724-36. [PMID: 16606371 DOI: 10.1111/j.1471-4159.2006.03767.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cortical nitric oxide (NO) production increases during hypoxia/ischemia in the immature brain and is associated with both neurotoxicity and mitochondrial dysfunction. Mitochondrial redistribution within the cell is critical to normal neuronal function, however, the effects of hypoxia on mitochondrial dynamics are not known. This study tested the hypothesis that hypoxia impairs mitochondrial movement via NO-mediated pathways. Fluorescently labeled mitochondria were studied using time-lapse digital video microscopy in cultured cortical neurons exposed either to hypoxia/re-oxygenation or to diethyleneamine/nitric oxide adduct, DETA-NO (100-500 microm). Two NO synthase inhibitors, were used to determine NO specificity. Mitochondrial mean velocity, the percentage of movement (i.e. the time spent moving) and mitochondrial morphology were analyzed. Exposure to hypoxia reduced mitochondrial movement to 10.4 +/- 1.3% at 0 h and 7.4 +/- 1.7% at 1 h of re-oxygenation, versus 25.6 +/- 1.4% in controls (p < 0.05). Mean mitochondrial velocity (microm s(-1)) decreased from 0.374 +/- 0.01 in controls to 0.146 +/- 0.01 at 0 h and 0.177 +/- 0.02 at 1 h of re-oxygenation (p < 0.001). Exposure to DETA-NO resulted in a significant decrease in mean mitochondrial velocity at all tested time points. Treatment with NG-nitro-L-arginine methyl ester (L-NAME) prevented the hypoxia-induced decrease in mitochondrial movement at 0 h (30.1 +/- 1.6%) and at 1 h (26.1 +/- 9%) of re-oxygenation. Exposure to either hypoxia/re-oxygenation or NO also resulted in the rapid decrease in mitochondrial size. Both hypoxia and NO exposure result in impaired mitochondrial movement and morphology in cultured cortical neurons. As the effect of hypoxia on mitochondrial movement and morphology can be partially prevented by a nitric oxide synthase (NOS) inhibitor, these data suggest that an NO-mediated pathway is at least partially involved.
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Affiliation(s)
- Santina A Zanelli
- Department of Pediatrics, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA
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12
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Calabrese V, Butterfield DA, Scapagnini G, Stella AMG, Maines MD. Redox regulation of heat shock protein expression by signaling involving nitric oxide and carbon monoxide: relevance to brain aging, neurodegenerative disorders, and longevity. Antioxid Redox Signal 2006; 8:444-77. [PMID: 16677090 DOI: 10.1089/ars.2006.8.444] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Increased free radical generation and decreased efficiency of the reparative/degradative mechanisms both primarily contribute to age-related elevation in the level of oxidative stress and brain damage. Excess formation of reactive oxygen and nitrogen species can cause proteasomal dysfunction and protein overloading. The major neurodegenerative diseases are all associated with the presence of abnormal proteins. Different integrated responses exist in the brain to detect oxidative stress which is controlled by several genes termed vitagenes, including the heat shock protein (HSP) system. Of the various HSPs, heme oxygenase-I (HO-1), by generating the vasoactive molecule carbon monoxide and the potent antioxidant bilirubin, could represent a protective system potentially active against brain oxidative injury. The HO-1 gene is redox regulated and its expression is modulated by redox active compounds, including nutritional antioxidants. Given the broad cytoprotective properties of the heat shock response, there is now strong interest in discovering and developing pharmacological agents capable of inducing the heat shock response. These findings have opened up new neuroprotective strategies, as molecules inducing this defense mechanism can be a therapeutic target to minimize the deleterious consequences associated with accumulation of conformationally aberrant proteins to oxidative stress, such as in neurodegenerative disorders and brain aging, with resulting prolongation of a healthy life span.
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Affiliation(s)
- Vittorio Calabrese
- Section of Biochemistry and Molecular Biology, Department of Chemistry, Faculty of Medicine, University of Catania, Catania, Italy
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13
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Kozhukhar AV, Yasinska IM, Sumbayev VV. Nitric oxide inhibits HIF-1alpha protein accumulation under hypoxic conditions: implication of 2-oxoglutarate and iron. Biochimie 2005; 88:411-8. [PMID: 16310922 DOI: 10.1016/j.biochi.2005.09.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2005] [Revised: 09/14/2005] [Accepted: 09/23/2005] [Indexed: 01/23/2023]
Abstract
Cells exposed to low oxygen conditions respond by initiating defense mechanisms, including the stabilization of hypoxia-inducible factor (HIF) 1alpha, a transcription factor that upregulates genes such as those involved in angiogenesis and glycolysis, which also plays a pivotal role in the regulation of cellular utilization of oxygen and is an essential regulator of angiogenesis in solid tumor and ischemic disorders. Nitric oxide and other inhibitors of mitochondrial respiration prevent the stabilization of HIF-1alpha during hypoxia. In the present study we found that nitric oxide inhibits HIF-1alpha accumulation under low oxygen (1%) conditions. The effect is supported by an increase in 3-nitrotyrosine and is more likely caused by the formation of peroxynitrite in the cells, which leads to the damage of mitochondria and their respiratory chain followed by the increase in 2-oxoglutarate (2-OG) and iron (the components needed to activate HIF-1alpha proline hydroxylases) concentrations in cell cytosol. The inhibiting effect of NO on HIF-1alpha accumulation was not observed in the cells lacking mitochondria. On the other hand the depletion of intracellular glutathione (GSH) was observed upon cell treatment with nitric oxide donors under hypoxic conditions. Treatment of those cells with N-acetyl cysteine (NAC) increased the amount of intracellular GSH and attenuated the NO effect and abolished the damage of mitochondria as well as 2-OG/iron release.
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Affiliation(s)
- Anna V Kozhukhar
- Department of Obstetrics and Gynecology, Odessa State Medical University, Marshala Govorova Street 28, Odessa 65009, Ukraine
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14
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Lai B, Zhang L, Dong LY, Zhu YH, Sun FY, Zheng P. Inhibition of Qi site of mitochondrial complex III with antimycin A decreases persistent and transient sodium currents via reactive oxygen species and protein kinase C in rat hippocampal CA1 cells. Exp Neurol 2005; 194:484-94. [PMID: 16022873 DOI: 10.1016/j.expneurol.2005.03.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2004] [Revised: 03/14/2005] [Accepted: 03/18/2005] [Indexed: 11/30/2022]
Abstract
Hypoxia-induced inhibition of Qi site of mitochondrial complex III under hypoxia has received attention, but its downstream pathways remain unclear. In this paper, we used Qi site inhibitor antimycin A to mimic the inhibition of the Qi site of mitochondrial complex III and studied the effects of the inhibition of this site on persistent sodium currents, transient sodium currents, and neuronal excitability in rat hippocampal CA1 cells with whole cell patch-clamp methods. The results showed that antimycin A decreased the amplitude of both persistent and transient sodium currents; antioxidant 2-mercaptopropionylglycine or 1,10 phenanthroline abolished the effect of antimycin A; the complex III Qo site inhibitor stigmatellin, the protein kinase C inhibitor chelerythrine, but not the protein kinase A inhibitor H89, canceled the effect of antimycin A; antimycin A decreased the amplitude of both persistent and transient sodium currents only at more depolarized membrane potentials and the decrease percentage of both persistent and transient sodium currents after antimycin A at potentials above -50 mV increased with the change in potentials toward more depolarized direction; exogenous application of H2O2 inhibited the amplitude of both persistent and transient sodium currents; the amount of current required to trigger spikes was increased and the number of spikes produced by varying levels of currents was decreased by antimycin A. These results suggest that the inhibition of Qi site of mitochondrial complex III decreases both persistent and transient sodium currents via reactive oxygen species and protein kinase C in rat hippocampal CA1 cells.
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Affiliation(s)
- Bin Lai
- State Key Laboratory of Medical Neurobiology, Fudan University Shanghai Medical College, 138 Yixueyuan Road, Shanghai 200032, People's Republic of China
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15
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Schild L, Reinheckel T, Reiser M, Horn TFW, Wolf G, Augustin W. Nitric oxide produced in rat liver mitochondria causes oxidative stress and impairment of respiration after transient hypoxia. FASEB J 2003; 17:2194-201. [PMID: 14656981 DOI: 10.1096/fj.02-1170com] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Nitric oxide (NO) is produced in mammals by different isoforms of NO synthase (NOS), including the constitutive mitochondrial enzyme (mtNOS). Here we demonstrate that the concentration of NO resulting from a mitochondrial NOS activity increases under hypoxic conditions in isolated rat liver mitochondria. We show that mitochondrially derived NO mediates the impairment of active (state 3) respiration as measured in the presence of the substrates glutamate and malate after reoxygenation. Simultaneously, NO induces oxidative stress in mitochondria, characterized by an increase in the amount of protein carbonyls and a decrease in glutathione (GSH). Both the accumulation of oxidative stress markers during and the impaired respiration after reoxygenation were prevented by blocking NO production with the NOS inhibitor L-NAME. These observations suggest that mitochondria are exposed to high amounts of NO generated by a mitochondrial NOS upon hypoxia/reoxygenation. Such increased NO levels, in turn, inhibit mitochondrial respiration and may cause oxidative stress that leads to irreversible impairment of mitochondria.
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Affiliation(s)
- Lorenz Schild
- Institute of Clinical Chemistry and Pathological Biochemistry, Department of Pathological Biochemistry, Otto-von-Guericke-University, Magdeburg, Germany.
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16
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Dedkova EN, Ji X, Lipsius SL, Blatter LA. Mitochondrial calcium uptake stimulates nitric oxide production in mitochondria of bovine vascular endothelial cells. Am J Physiol Cell Physiol 2003; 286:C406-15. [PMID: 14512291 DOI: 10.1152/ajpcell.00155.2003] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although nitric oxide (NO) is a known modulator of cell respiration in vascular endothelium, the presence of a mitochondria-specific nitric oxide synthase (mtNOS) in these cells is still a controversial issue. We have used laser scanning confocal microscopy in combination with the NO-sensitive fluorescent dye DAF-2 to monitor changes in NO production by mitochondria of calf vascular endothelial (CPAE) cells. Cells were loaded with the membrane-permeant NO-sensitive dye 4,5-diaminofluorescein (DAF-2) diacetate and subsequently permeabilized with digitonin to remove cytosolic DAF-2 to allow measurements of NO production in mitochondria ([NO]mt). Stimulation of mitochondrial Ca2+ uptake by exposure to different cytoplasmic Ca2+ concentrations (1, 2, and 5 microM) resulted in a dose-dependent increase of NO production by mitochondria. This increase of [NO]mt was sensitive to the NOS antagonist l-N5-(1-iminoethyl)ornithine and the calmodulin antagonist calmidazolium (R-24571), demonstrating the endogenous origin of NO synthesis and its calmodulin dependence. Collapsing the mitochondrial membrane potential with the protonophore FCCP or blocking the mitochondrial Ca2+ uniporter with ruthenium red, as well as blocking the respiratory chain with antimycin A in combination with oligomycin, inhibited mitochondrial NO production. Addition of the NO donor spermine NONOate caused a profound increase in DAF-2 fluorescence that was not affected by either of these treatments. The mitochondrial origin of the DAF-2 signals was confirmed by colocalization with the mitochondrial marker MitoTracker Red and by the observation that disruption of caveolae (where cytoplasmic NOS is localized) formation with methyl-beta-cyclodextrin did not prevent the increase of DAF-2 fluorescence. The activation of mitochondrial calcium uptake stimulates mtNOS phosphorylation (at Ser-1177) which was prevented by FCCP. The data demonstrate that stimulation of mitochondrial Ca2+ uptake activates NO production in mitochondria of CPAE cells. This indicates the presence of a mitochondria-specific NOS that can provide a fast local modulatory effect of NO on cell respiration, membrane potential, and apoptosis.
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Affiliation(s)
- Elena N Dedkova
- Department of Physiology, Loyola University Chicago, 2160 S. First Ave., Maywood, IL 60153, USA
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Latini A, Borba Rosa R, Scussiato K, Llesuy S, Belló-Klein A, Wajner M. 3-Hydroxyglutaric acid induces oxidative stress and decreases the antioxidant defenses in cerebral cortex of young rats. Brain Res 2002; 956:367-73. [PMID: 12445707 DOI: 10.1016/s0006-8993(02)03573-4] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Glutaryl-CoA dehydrogenase deficiency (GDD) is an inherited neurometabolic disorder biochemically characterized by tissue accumulation of glutaric, 3-hydroxyglutaric (3-OHGA) and glutaconic acids and clinically by severe neurological symptoms and cerebral atrophy whose pathophysiology is poorly known. In the present study we investigated the effect of 3-OHGA, considered the main neurotoxin in GDD, on the lipoperoxidation parameters chemiluminescence and thiobarbituric acid-reactive species (TBA-RS), and on the amount of nitric oxide metabolites in cerebral cortex of young rats. Total radical-trapping antioxidant potential (TRAP), which reflects the tissue antioxidant defenses, was also examined. We observed that 3-OHGA significantly increased chemiluminescence, TBA-RS and nitric oxide metabolites, in contrast to TRAP, which was decreased by the metabolite. The data indicate a stimulation of lipid peroxidation and free radical production, and a reduction of the tissue antioxidant defenses caused by the metabolite. In case these findings also occur in the human condition, it may be presumed that oxidative stress is involved in the brain damage observed in GDD.
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Affiliation(s)
- Alexandra Latini
- Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal de Río Grande do Sul, Porto Alegre, RS, Brazil
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18
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Horn TFW, Wolf G, Duffy S, Weiss S, Keilhoff G, MacVicar BA. Nitric oxide promotes intracellular calcium release from mitochondria in striatal neurons. FASEB J 2002; 16:1611-22. [PMID: 12374784 DOI: 10.1096/fj.02-0126com] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Overproduction of nitric oxide by NMDA receptor stimulation is implicated in calcium deregulation and neurodegeneration of striatal neurons. We investigated the involvement of nitric oxide (NO) in inducing intracellular calcium release and in modifying calcium transients evoked by NMDA. NO application (4-10 microM) reversibly and repeatedly increased the intracellular calcium concentration [Ca2+]i in Fura-2- or fluo-3-loaded cultured mouse striatal neurons. NO-induced [Ca2+]i responses persisted in the absence of extracellular calcium, indicating that Ca2+ was released from intracellular stores. The source of calcium was distinct from [Ca2+]i-activated (ruthenium red and ryanodine sensitive) or IP3-activated (thapsigargin-sensitive) Ca2+ stores and was not dependent on cGMP production because a cell permeant analog, 8-bromo-cGMP, did not increase basal [Ca2+]i. Glucose removal potentiated the NO-induced release of [Ca2+]i. In contrast, pretreatment with either the mitochondrial uncoupler carbonyl cyanide m-chlorophenylhydrazone or cyclosporin A, a blocker of the mitochondrial permeability transition pore, prevented the [Ca2+]i increase after NO. The rise in [Ca2+]i during NO exposure was preceded by a decrease in mitochondrial membrane potential that was partly reversible during washout. Repeated applications of NMDA induced irreversible [Ca2+]i responses in a subpopulation of striatal cells that were greatly reduced by the NOS inhibitor N omega-nitro-l-arginine. Calcium transients were prolonged by conjoint application of NMDA and NO. We conclude that NMDA-evoked [Ca2+]i transients are modulated by endogenous NO production, which leads to release of calcium from the mitochondrial pool. An NO-activated mitochondrial permeability transition pore may lead to cell death after overstimulation of NMDA receptors.
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Affiliation(s)
- Thomas F W Horn
- Institute for Medical Neurobiology, University of Magdeburg, Germany.
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Gonzalez-Barrios JA, Escalante B, Valdés J, León-Chávez BA, Martinez-Fong D. Nitric oxide and nitric oxide synthases in the fetal cerebral cortex of rats following transient uteroplacental ischemia. Brain Res 2002; 945:114-22. [PMID: 12113958 DOI: 10.1016/s0006-8993(02)02746-4] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The effect of transient uteroplacental ischemia on nitric oxide (NO) levels, enzymatic activity, and expression of NO synthase (NOS) isoforms was studied in fetal rat brains. Fetuses were subjected to ischemia by clamping the uterine arteries for 5 min on gestational day 17 (GD17). At different times after ischemia, fetuses were delivered by Cesarean section under anesthesia to obtain the brains. Transient uteroplacental ischemia produced a time dependent increase in nitrite levels in the brain, reaching a maximum value (300 +/- 25% of baseline) 24 h after uterine artery occlusion and remaining elevated as long as 48 h. Significantly increased nitrite levels were found in the cerebral cortex but not in the mesencephalon and cerebellum. The ischemia-induced increment in nitrite levels was totally blocked by either L-NAME (10 mg/kg) or AMT (0.65 mg/kg) administered i.p. 1 h before uterine artery occlusion. Both Ca(2+)-dependent and Ca(2+)-independent NOS activities in the cerebral cortex remained significantly increased with respect to controls after 24 h following the ischemia. Reverse transcriptase-polymerase chain reaction showed augmented levels of mRNAs for both nNOS and iNOS when compared with controls at 8 h after ischemia. At 36 h, nNOS mRNA returned to basal levels whereas eNOS mRNA levels increased and iNOS mRNA remained elevated. Our results show that the three NOS isoforms participate in increasing NO levels after transient ischemia and suggest a biphasic and differential regulation of the expression of constitutive NOS isoforms in the rat cerebral cortex.
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Affiliation(s)
- Juan Antonio Gonzalez-Barrios
- Departamento de Fisiología, Biofísica y Neurociencias, Cinvestav-IPN., Apartado postal 14-740, 07000, México DF, Mexico
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20
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Agani FH, Puchowicz M, Chavez JC, Pichiule P, LaManna J. Role of nitric oxide in the regulation of HIF-1alpha expression during hypoxia. Am J Physiol Cell Physiol 2002; 283:C178-86. [PMID: 12055086 DOI: 10.1152/ajpcell.00381.2001] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Hypoxia-inducible factor-1 (HIF-1), a heterodimeric transcription factor consisting of HIF-1alpha and HIF-1beta subunits, controls the expression of a large number of genes involved in the regulation of cellular responses to reduced oxygen availability. The oxygen-regulated subunit, HIF-1alpha, is stabilized in cells exposed to hypoxia. The regulation of hypoxic responses by nitric oxide (NO) is believed to have wide pathophysiological relevance, thus we investigated whether NO affects HIF-1 activation in hypoxic cells. Here we show that NO generated from NO donors prevented HIF-1alpha hypoxic accumulation in Hep 3B and PC-12 cells. Addition of a glutathione analog or peroxynitrite scavengers prevented the NO-induced inhibition of HIF-1alpha accumulation in both cell lines. Exposure to NO was associated with inhibition of mitochondrial electron transport and compensatory glycolysis, which maintained normal cellular ATP content. Succinate, a Krebs cycle intermediate and respiratory chain substrate, restored HIF-1alpha hypoxic induction in the cells, suggesting involvement of mitochondria in regulation of HIF-1alpha accumulation during hypoxia. Regulation of HIF-1alpha by NO is an additional important mechanism by which NO might modulate cellular responses to hypoxia in mammalian cells.
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Affiliation(s)
- Faton H Agani
- Department of Anatomy, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4938, USA.
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21
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Abstract
Prematurity-mediated cerebral damage has been associated with oxidative stress. The aim of the present work was to study the possible role played by free oxygen radicals generated by mitochondrial respiratory function in cerebral injury in preterm neonates. Our results show that whereas total glutathione concentrations are similar in term and preterm neonates, the GSH/GSSG ratio decreases sharply in preterm neonates immediately after birth. This effect is not due to a lack of enzymes involved in GSH regeneration, such as glutathione reductase and glucose-6-phosphate dehydrogenase, but to a significant increase in free-radical generation in preterm rat brain as shown by the increase in lipoperoxidation. Because the mitochondrion is the main source of free radicals in the cell, mitochondrial respiratory function was studied in the brain of preterm neonates. Our results show that prematurity prevented the postnatal increases in complex II-III activity and ATP concentrations that occur in term neonates at 5 min after delivery. All these effects were counteracted by the oxygen supply, suggesting that the inhibition of mitochondrial function is caused by restricted oxygen availability. Consequently, cerebral damage associated with prematurity may be mediated by mitochondrial free-radical generation as a consequence of hypoxia undergone by preterm neonates at birth.
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Affiliation(s)
- Rosa Sánchez-Alvarez
- Departamento de Bioquímica y Biología Molecular, Facultad de Farmacia, Universidad de Salamanca, Salamanca, Spain
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22
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Spagnuolo MS, Cigliano L, Balestrieri M, Porta A, Abrescia P. Synthesis of ascorbate and urate in the ovary of water buffalo. Free Radic Res 2001; 35:233-43. [PMID: 11697122 DOI: 10.1080/10715760100300771] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Blood flow interruption is associated with oxygen depletion and loss of factors for function and survival in downstream tissues or cells. Hypoxia and absence of gonadotropins trigger apoptosis and atresia in the ovary. We studied the antioxidant response of follicular cells to plasma deprivation in ovaries dissected from water buffalo. Aliquots of follicular fluid were aspirated from each antral follicle, before and during incubation of the ovaries at 39 degrees C. Urate, ascorbate, retinol and alpha-tocopherol in the fluid were, titrated by High Performance Liquid Chromatography (HPLC) with spectrophotometric or spectrofluorimetric detection. The total antioxidant capacity of follicular fluid was determined as absorbance decrease, following addition of a source of radical chromophores. The more the incubation progressed, the higher levels of urate, ascorbate and total antioxidant capacity were found. Conversely, changes in concentration of the liposoluble antioxidants were not observed. Ascorbate synthesizing activity in the follicle was demonstrated by detecting the enzyme L-gulono-gamma-lactone oxidase in microsomes prepared from granulosa cells. These cells were also analyzed for the expression of the enzyme CPP32. The enzyme level, measured as DEVD-p-nitroanilide cleaving activity, was found related with the immunoreactivity to anti-CPP32 antibodies. Negative correlation between the enzyme activity (which is known to be induced by peroxynitrite) and the follicular level of urate (which scavenges peroxynitrite) was also observed. The amount of nitrotyrosine, a product of peroxynitrite attack on proteins, was measured in follicular fluids by Enzyme Linked ImmunoSorbent Assay (ELISA). This amount was found positively correlated with the CPP32 activity, and negatively correlated with the urate level in follicular fluid. Alterations in concentrations of ascorbate or urate may be associated with oxidative stress during follicular atresia.
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Affiliation(s)
- M S Spagnuolo
- Dipartimento di Fisiologia Generale ed Ambientale, Università di Napoli Federico II via Mezzocannone 8, 80134 Napoli, Italy
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Galleguillos M, Valenzuela MA, Riquelme R, Sanhueza E, Sánchez G, Figueroa JP, Llanos AJ. Nitric oxide synthase activity in brain tissues from llama fetuses submitted to hypoxemia. Comp Biochem Physiol A Mol Integr Physiol 2001; 129:605-14. [PMID: 11423330 DOI: 10.1016/s1095-6433(01)00299-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The fetal llama (Lama glama; a species adapted to live in chronic hypoxia in the highlands of the Andes) did not increase cerebral blood flow and reduce the brain oxygen uptake during hypoxemia. Although nitric oxide (NO) is a normal mediator in the regulation of vascular tone and synaptic transmission, NO overproduction by hypoxemia could produce neuronal damage. We hypothesized that nitric oxide synthase (NOS) activity is either maintained or reduced in the central nervous system of the llama fetuses submitted to chronic hypoxemia. Approximately 85% of the Ca(2+)-dependent NOS activity was soluble, at least 12% was associated with the mitochondrial fraction, and less than 5% remains associated with microsomes. To understand the role of NO in chronic hypoxemia, we determined the effect of 24-h hypoxemia on NOS activity in the central nervous system. No changes in activity or the subcellular distribution of NOS activity in brain tissues after hypoxemia were found. We proposed that the lack of changes in NOS activity in the llama under hypoxemia could be a cytoprotective mechanism inherent to the llama, against possible toxic effects of NO.
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Affiliation(s)
- M Galleguillos
- Departamento de Ciencias Biológicas Animales, Facultad de Ciencias Veterinarias y Pecuarias, Universidad de Chile, Santiago, Chile
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24
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Toborek M, Garrido R, Malecki A, Kaiser S, Mattson MP, Hennig B, Young B. Nicotine attenuates arachidonic acid-induced overexpression of nitric oxide synthase in cultured spinal cord neurons. Exp Neurol 2000; 161:609-20. [PMID: 10686080 DOI: 10.1006/exnr.1999.7308] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Primary spinal cord trauma can initiate a cascade of pathophysiologic events which markedly contribute to the expansion and amplification of the primary insult. The detailed mechanisms of these secondary neurochemical reactions are largely unknown; however, they involve membrane lipid derangements with the release of free fatty acids, in particular, arachidonic acid (AA). AA can induce several injury effects on spinal cord neurons. We hypothesize that upregulation of nitric oxide synthase (NOS) is among the most important mechanisms of arachidonic-acid-induced neuronal dysfunction and that nicotine can attenuate this effect. To study these hypotheses, spinal cord neurons were exposed to AA and/or nicotine, and several markers of neuronal nitric oxide synthase (nNOS) metabolism were measured. In addition, cotreatments with either inhibitors of nicotinic receptors or inhibitors of specific NOS isoforms were employed. Treatment with AA markedly increased activity of nNOS, as well as mRNA and protein levels of this enzyme. Changes in nNOS expression were accompanied by an increase in cellular cGMP and medium nitrite levels. Pretreatment with nicotine decreased AA-induced overexpression of nNOS and elevation of nitrite levels. In addition, it appeared that these nicotine effects could be partially modulated both by the alpha7 nicotinic receptors or by nonreceptor mechanisms. Alternatively, the observed changes could also be mediated by an alternate nicotinic receptor mechanism which is not blocked by alpha-bungarotoxin or mecamylamine. Results of the present study indicate that exposure to AA can lead to induction of nNOS in cultured spinal cord neurons. In addition, nicotine can exert a neuroprotective effect by attenuation of AA-induced upregulation of nNOS metabolism. These data may have therapeutic implications for the treatment of acute spinal cord trauma.
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Affiliation(s)
- M Toborek
- Department of Surgery, University of Kentucky, Lexington, Kentucky, 40536, USA.
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Almeida A, Bolaños JP, Medina JM. Nitric oxide mediates brain mitochondrial maturation immediately after birth. FEBS Lett 1999; 452:290-4. [PMID: 10386608 DOI: 10.1016/s0014-5793(99)00628-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The possible role of nitric oxide (*NO) in brain mitochondrial maturation was studied. Within the first 5 min after birth, a sharp increase in ATP concentrations was observed, coinciding with an increase in mitochondrial complex II-III (succinate-cytochrome c reductase) activity, while complex I (NADH-CoQ1 reductase) and complex IV (cytochrome c oxidase) activities remained unchanged. Under the same circumstances, cGMP concentrations were increased by 5 min after birth, correlating significantly with ATP concentrations. Since ATP concentrations also correlated significantly with mitochondrial complex II-III activity, these three parameters may be associated. Inhibition of *NO synthase activity brought about by the administration of N(omega)-nitro-L-arginine monomethyl ester to mothers prevented the postnatal increase in cGMP and ATP levels and complex II-III activity. These results suggest that early postnatal mitochondrial maturation in the brain is a *NO-mediated process.
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Affiliation(s)
- A Almeida
- Departamento de Bioquímica y Biología Molecular, Facultad de Farmacia, Universidad de Salamanca, Spain
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26
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Bolaños JP, Almeida A. Roles of nitric oxide in brain hypoxia-ischemia. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1411:415-36. [PMID: 10320673 DOI: 10.1016/s0005-2728(99)00030-4] [Citation(s) in RCA: 230] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A large body of evidence has appeared over the last 6 years suggesting that nitric oxide biosynthesis is a key factor in the pathophysiological response of the brain to hypoxia-ischemia. Whilst studies on the influence of nitric oxide in this phenomenon initially offered conflicting conclusions, the use of better biochemical tools, such as selective inhibition of nitric oxide synthase (NOS) isoforms or transgenic animals, is progressively clarifying the precise role of nitric oxide in brain ischemia. Brain ischemia triggers a cascade of events, possibly mediated by excitatory amino acids, yielding the activation of the Ca2+-dependent NOS isoforms, i.e. neuronal NOS (nNOS) and endothelial NOS (eNOS). However, whereas the selective inhibition of nNOS is neuroprotective, selective inhibition of eNOS is neurotoxic. Furthermore, mainly in glial cells, delayed ischemia or reperfusion after an ischemic episode induces the expression of Ca2+-independent inducible NOS (iNOS), and its selective inhibition is neuroprotective. In conclusion, it appears that activation of nNOS or induction of iNOS mediates ischemic brain damage, possibly by mitochondrial dysfunction and energy depletion. However, there is a simultaneous compensatory response through eNOS activation within the endothelium of blood vessels, which mediates vasodilation and hence increases blood flow to the damaged brain area.
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Affiliation(s)
- J P Bolaños
- Departamento de Bioquímica y Biología Molecular, Universidad de Salamanca, Edificio Departamental, Campus Miguel de Unamuno, 37007, Salamanca, Spain.
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27
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Heales SJ, Bolaños JP, Stewart VC, Brookes PS, Land JM, Clark JB. Nitric oxide, mitochondria and neurological disease. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1410:215-28. [PMID: 10076028 DOI: 10.1016/s0005-2728(98)00168-6] [Citation(s) in RCA: 364] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Damage to the mitochondrial electron transport chain has been suggested to be an important factor in the pathogenesis of a range of neurological disorders, such as Parkinson's disease, Alzheimer's disease, multiple sclerosis, stroke and amyotrophic lateral sclerosis. There is also a growing body of evidence to implicate excessive or inappropriate generation of nitric oxide (NO) in these disorders. It is now well documented that NO and its toxic metabolite, peroxynitrite (ONOO-), can inhibit components of the mitochondrial respiratory chain leading, if damage is severe enough, to a cellular energy deficiency state. Within the brain, the susceptibility of different brain cell types to NO and ONOO- exposure may be dependent on factors such as the intracellular reduced glutathione (GSH) concentration and an ability to increase glycolytic flux in the face of mitochondrial damage. Thus neurones, in contrast to astrocytes, appear particularly vulnerable to the action of these molecules. Following cytokine exposure, astrocytes can increase NO generation, due to de novo synthesis of the inducible form of nitric oxide synthase (NOS). Whilst the NO/ONOO- so formed may not affect astrocyte survival, these molecules may diffuse out to cause mitochondrial damage, and possibly cell death, to other cells, such as neurones, in close proximity. Evidence is now available to support this scenario for neurological disorders, such as multiple sclerosis. In other conditions, such as ischaemia, increased availability of glutamate may lead to an activation of a calcium-dependent nitric oxide synthase associated with neurones. Such increased/inappropriate NO formation may contribute to energy depletion and neuronal cell death. The evidence available for NO/ONOO--mediated mitochondrial damage in various neurological disorders is considered and potential therapeutic strategies are proposed.
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Affiliation(s)
- S J Heales
- Department of Clinical Biochemistry, National Hospital, Queen Square, London WC1N 3BG, UK.
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28
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Nitric oxide acutely inhibits neuronal energy production. The Committees on Neurobiology and Cell Physiology. J Neurosci 1999. [PMID: 9870946 DOI: 10.1523/jneurosci.19-01-00147.1999] [Citation(s) in RCA: 148] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Disruption of mitochondrial respiration has been proposed as an action of nitric oxide (NO) responsible for its toxicity, but the effects of NO on the energetics of intact central neurons have not been reported. We examined the effects of NO on mitochondrial function and energy metabolism in cultured hippocampal neurons. The application of NO from NO donors or from dissolved gas produced a rapid, reversible depolarization of mitochondrial membrane potential, as detected by rhodamine-123 fluorescence. NO also produced a progressive concentration-dependent depletion of cellular ATP over 20 min exposures. The energy depletion produced by higher levels of NO (2 microM or more) was profound and irreversible and proceeded to subsequent neuronal death. In contrast to the effects of NO, mitochondrial protonophores produced complete depolarizations of mitochondrial membrane potential but depleted the neuronal ATP stores only partially. Inhibitors of mitochondrial oxidative phosphorylation (rotenone or 3-nitropropionic acid) or of glycolysis (iodoacetate plus pyruvate) also produced only partial ATP depletion, suggesting that either process alone could partially maintain ATP stores. Only by combining the inhibition of glycolytic energy production with the inhibition of mitochondria could the effects of NO in depleting energy and inducing delayed toxicity be duplicated. These results show that NO has rapid inhibitory actions on mitochondrial metabolism in living neurons. However, the severe ATP-depleting effects of high concentrations of NO are not fully explained by the direct effects on mitochondrial activity alone but must involve the inhibition of glycolysis as well. These inhibitory effects on energy production may contribute to the delayed toxicity of NO in vitro and in ischemic stroke.
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