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Pérez-Sala D, Pajares MA. Appraising the Role of Astrocytes as Suppliers of Neuronal Glutathione Precursors. Int J Mol Sci 2023; 24:ijms24098059. [PMID: 37175763 PMCID: PMC10179008 DOI: 10.3390/ijms24098059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 04/25/2023] [Accepted: 04/25/2023] [Indexed: 05/15/2023] Open
Abstract
The metabolism and intercellular transfer of glutathione or its precursors may play an important role in cellular defense against oxidative stress, a common hallmark of neurodegeneration. In the 1990s, several studies in the Neurobiology field led to the widely accepted notion that astrocytes produce large amounts of glutathione that serve to feed neurons with precursors for glutathione synthesis. This assumption has important implications for health and disease since a reduction in this supply from astrocytes could compromise the capacity of neurons to cope with oxidative stress. However, at first glance, this shuttling would imply a large energy expenditure to get to the same point in a nearby cell. Thus, are there additional underlying reasons for this expensive mechanism? Are neurons unable to import and/or synthesize the three non-essential amino acids that are the glutathione building blocks? The rather oxidizing extracellular environment favors the presence of cysteine (Cys) as cystine (Cis), less favorable for neuronal import. Therefore, it has also been proposed that astrocytic GSH efflux could induce a change in the redox status of the extracellular space nearby the neurons, locally lowering the Cis/Cys ratio. This astrocytic glutathione release would also increase their demand for precursors, stimulating Cis uptake, which these cells can import, further impacting the local decline of the Cis/Cys ratio, in turn, contributing to a more reduced extracellular environment and subsequently favoring neuronal Cys import. Here, we revisit the experimental evidence that led to the accepted hypothesis of astrocytes acting as suppliers of neuronal glutathione precursors, considering recent data from the Human Protein Atlas. In addition, we highlight some potential drawbacks of this hypothesis, mainly supported by heterogeneous cellular models. Finally, we outline additional and more cost-efficient possibilities by which astrocytes could support neuronal glutathione levels, including its shuttling in extracellular vesicles.
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Affiliation(s)
- Dolores Pérez-Sala
- Department of Structural and Chemical Biology, Centro de Investigaciones Biológicas Margarita Salas (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - María A Pajares
- Department of Structural and Chemical Biology, Centro de Investigaciones Biológicas Margarita Salas (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain
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Ong CEB, Patchett AL, Darby JM, Chen J, Liu GS, Lyons AB, Woods GM, Flies AS. NLRC5 regulates expression of MHC-I and provides a target for anti-tumor immunity in transmissible cancers. J Cancer Res Clin Oncol 2021; 147:1973-1991. [PMID: 33797607 PMCID: PMC8017436 DOI: 10.1007/s00432-021-03601-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 03/16/2021] [Indexed: 12/16/2022]
Abstract
Purpose Downregulation of MHC class I (MHC-I) is a common immune evasion strategy of many cancers. Similarly, two allogeneic clonal transmissible cancers have killed thousands of wild Tasmanian devils (Sarcophilus harrisii) and also modulate MHC-I expression to evade anti-cancer and allograft responses. IFNG treatment restores MHC-I expression on devil facial tumor (DFT) cells but is insufficient to control tumor growth. Transcriptional co-activator NLRC5 is a master regulator of MHC-I in humans and mice but its role in transmissible cancers remains unknown. In this study, we explored the regulation and role of MHC-I in these unique genetically mis-matched tumors. Methods We used transcriptome and flow cytometric analyses to determine how MHC-I shapes allogeneic and anti-tumor responses. Cell lines that overexpress NLRC5 to drive antigen presentation, and B2M-knockout cell lines incapable of presenting antigen on MHC-I were used to probe the role of MHC-I in rare cases of tumor regressions. Results Transcriptomic results suggest that NLRC5 plays a major role in MHC-I regulation in devils. NLRC5 was shown to drive the expression of many components of the antigen presentation pathway but did not upregulate PDL1. Serum from devils with tumor regressions showed strong binding to IFNG-treated and NLRC5 cell lines; antibody binding to IFNG-treated and NRLC5 transgenic tumor cells was diminished or absent following B2M knockout. Conclusion MHC-I could be identified as a target for anti-tumor and allogeneic immunity. Consequently, NLRC5 could be a promising target for immunotherapy and vaccines to protect devils from transmissible cancers and inform development of transplant and cancer therapies for humans. Supplementary Information The online version contains supplementary material available at 10.1007/s00432-021-03601-x.
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Affiliation(s)
- Chrissie E B Ong
- Menzies Institute for Medical Research, College of Health and Medicine, University of Tasmania, Private Bag 23, Hobart TAS 7000, Australia
| | - Amanda L Patchett
- Menzies Institute for Medical Research, College of Health and Medicine, University of Tasmania, Private Bag 23, Hobart TAS 7000, Australia
| | - Jocelyn M Darby
- Menzies Institute for Medical Research, College of Health and Medicine, University of Tasmania, Private Bag 23, Hobart TAS 7000, Australia
| | - Jinying Chen
- Menzies Institute for Medical Research, College of Health and Medicine, University of Tasmania, Private Bag 23, Hobart TAS 7000, Australia.,Department of Ophthalmology, The First Affiliated Hospital of Jinan University, Guangzhou, China
| | - Guei-Sheung Liu
- Menzies Institute for Medical Research, College of Health and Medicine, University of Tasmania, Private Bag 23, Hobart TAS 7000, Australia.,Ophthalmology, Department of Surgery, University of Melbourne, East Melbourne, Australia
| | - A Bruce Lyons
- Tasmanian School of Medicine, College of Health and Medicine, University of Tasmania, Hobart, TAS, Australia
| | - Gregory M Woods
- Menzies Institute for Medical Research, College of Health and Medicine, University of Tasmania, Private Bag 23, Hobart TAS 7000, Australia
| | - Andrew S Flies
- Menzies Institute for Medical Research, College of Health and Medicine, University of Tasmania, Private Bag 23, Hobart TAS 7000, Australia.
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3
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Gonçalves CA, Rodrigues L, Bobermin LD, Zanotto C, Vizuete A, Quincozes-Santos A, Souza DO, Leite MC. Glycolysis-Derived Compounds From Astrocytes That Modulate Synaptic Communication. Front Neurosci 2019; 12:1035. [PMID: 30728759 PMCID: PMC6351787 DOI: 10.3389/fnins.2018.01035] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 12/20/2018] [Indexed: 12/14/2022] Open
Abstract
Based on the concept of the tripartite synapse, we have reviewed the role of glucose-derived compounds in glycolytic pathways in astroglial cells. Glucose provides energy and substrate replenishment for brain activity, such as glutamate and lipid synthesis. In addition, glucose metabolism in the astroglial cytoplasm results in products such as lactate, methylglyoxal, and glutathione, which modulate receptors and channels in neurons. Glucose has four potential destinations in neural cells, and it is possible to propose a crossroads in “X” that can be used to describe these four destinations. Glucose-6P can be used either for glycogen synthesis or the pentose phosphate pathway on the left and right arms of the X, respectively. Fructose-6P continues through the glycolysis pathway until pyruvate is formed but can also act as the initial compound in the hexosamine pathway, representing the left and right legs of the X, respectively. We describe each glucose destination and its regulation, indicating the products of these pathways and how they can affect synaptic communication. Extracellular L-lactate, either generated from glucose or from glycogen, binds to HCAR1, a specific receptor that is abundantly localized in perivascular and post-synaptic membranes and regulates synaptic plasticity. Methylglyoxal, a product of a deviation of glycolysis, and its derivative D-lactate are also released by astrocytes and bind to GABAA receptors and HCAR1, respectively. Glutathione, in addition to its antioxidant role, also binds to ionotropic glutamate receptors in the synaptic cleft. Finally, we examined the hexosamine pathway and evaluated the effect of GlcNAc-modification on key proteins that regulate the other glucose destinations.
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Affiliation(s)
- Carlos-Alberto Gonçalves
- Department of Biochemistry, Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, Brazil
| | - Letícia Rodrigues
- Department of Biochemistry, Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, Brazil
| | - Larissa D Bobermin
- Department of Biochemistry, Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, Brazil
| | - Caroline Zanotto
- Department of Biochemistry, Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, Brazil
| | - Adriana Vizuete
- Department of Biochemistry, Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, Brazil
| | - André Quincozes-Santos
- Department of Biochemistry, Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, Brazil
| | - Diogo O Souza
- Department of Biochemistry, Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, Brazil
| | - Marina C Leite
- Department of Biochemistry, Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, Brazil
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4
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Garaschuk O, Semchyshyn HM, Lushchak VI. Healthy brain aging: Interplay between reactive species, inflammation and energy supply. Ageing Res Rev 2018; 43:26-45. [PMID: 29452266 DOI: 10.1016/j.arr.2018.02.003] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 11/13/2017] [Accepted: 02/08/2018] [Indexed: 02/07/2023]
Abstract
Brains' high energy expenditure with preferable utilization of glucose and ketone bodies, defines the specific features of its energy homeostasis. The extensive oxidative metabolism is accompanied by a concomitant generation of high amounts of reactive oxygen, nitrogen, and carbonyl species, which will be here collectively referred to as RONCS. Such metabolism in combination with high content of polyunsaturated fatty acids creates specific problems in maintaining brains' redox homeostasis. While the levels of products of interaction between RONCS and cellular components increase slowly during the first two trimesters of individuals' life, their increase is substantially accelerated towards the end of life. Here we review the main mechanisms controlling the redox homeostasis of the mammalian brain, their age-dependencies as well as their adaptive potential, which might turn out to be much higher than initially assumed. According to recent data, the organism seems to respond to the enhancement of aging-related toxicity by forming a new homeostatic set point. Therefore, further research will focus on understanding the properties of the new set point(s), the general nature of this phenomenon and will explore the limits of brains' adaptivity.
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Affiliation(s)
- O Garaschuk
- Department of Neurophysiology, Institute of Physiology, University of Tübingen, 72074 Tübingen, Germany.
| | - H M Semchyshyn
- Department of Biochemistry and Biotechnology, Vasyl Stefanyk Precarpathian National University, 57 Shevchenko Str, Ivano-Frankivsk, 76018, Ukraine.
| | - V I Lushchak
- Department of Biochemistry and Biotechnology, Vasyl Stefanyk Precarpathian National University, 57 Shevchenko Str, Ivano-Frankivsk, 76018, Ukraine.
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5
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Takemoto Y. l-Cysteine and l-AP4 microinjections in the rat caudal ventrolateral medulla decrease arterial blood pressure. Auton Neurosci 2014; 186:45-53. [DOI: 10.1016/j.autneu.2014.09.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Revised: 09/12/2014] [Accepted: 09/21/2014] [Indexed: 02/07/2023]
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6
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Baranes K, Moshe H, Alon N, Schwartz S, Shefi O. Neuronal growth on L- and D-cysteine self-assembled monolayers reveals neuronal chiral sensitivity. ACS Chem Neurosci 2014; 5:370-6. [PMID: 24559496 DOI: 10.1021/cn500015s] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Studying the interaction between neuronal cells and chiral molecules is fundamental for the design of novel biomaterials and drugs. Chirality influences all biological processes that involve intermolecular interaction. One common method used to study cellular interactions with different enantiomeric targets is the use of chiral surfaces. Based on previous studies that demonstrated the importance of cysteine in the nervous system, we studied the effect of L- and D-cysteine on single neuronal growth. L-Cysteine, which normally functions as a neuromodulator or a neuroprotective antioxidant, causes damage at elevated levels, which may occur post trauma. In this study, we grew adult neurons in culture enriched with L- and D-cysteine as free compounds or as self-assembled monolayers of chiral surfaces and examined the effect on the neuronal morphology and adhesion. Notably, we have found that exposure to the L-cysteine enantiomer inhibited, and even prevented, neuronal attachment more severely than exposure to the D-cysteine enantiomer. Atop the L-cysteine surfaces, neuronal growth was reduced and degenerated. Since the cysteine molecules were attached to the surface via the thiol groups, the neuronal membrane was exposed to the molecular chiral site. Thus, our results have demonstrated high neuronal chiral sensitivity, revealing chiral surfaces as indirect regulators of neuronal cells and providing a reference for studying chiral drugs.
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Affiliation(s)
- Koby Baranes
- Faculty of Engineering, ‡Department of Chemistry, §Gonda Multidisciplinary Brain Research
Center, and ∥Bar Ilan Institute of Nanotechnologies and Advanced Materials, Bar Ilan University, 5290002 Ramat Gan, Israel
| | - Hagay Moshe
- Faculty of Engineering, ‡Department of Chemistry, §Gonda Multidisciplinary Brain Research
Center, and ∥Bar Ilan Institute of Nanotechnologies and Advanced Materials, Bar Ilan University, 5290002 Ramat Gan, Israel
| | - Noa Alon
- Faculty of Engineering, ‡Department of Chemistry, §Gonda Multidisciplinary Brain Research
Center, and ∥Bar Ilan Institute of Nanotechnologies and Advanced Materials, Bar Ilan University, 5290002 Ramat Gan, Israel
| | - Shmulik Schwartz
- Faculty of Engineering, ‡Department of Chemistry, §Gonda Multidisciplinary Brain Research
Center, and ∥Bar Ilan Institute of Nanotechnologies and Advanced Materials, Bar Ilan University, 5290002 Ramat Gan, Israel
| | - Orit Shefi
- Faculty of Engineering, ‡Department of Chemistry, §Gonda Multidisciplinary Brain Research
Center, and ∥Bar Ilan Institute of Nanotechnologies and Advanced Materials, Bar Ilan University, 5290002 Ramat Gan, Israel
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7
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Takemoto Y. Functional cardiovascular action of l-cysteine microinjected into pressor sites of the rostral ventrolateral medulla of the rat. Amino Acids 2013; 46:863-72. [DOI: 10.1007/s00726-013-1651-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 12/12/2013] [Indexed: 02/07/2023]
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8
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Fay JF, Farrens DL. The membrane proximal region of the cannabinoid receptor CB1 N-terminus can allosterically modulate ligand affinity. Biochemistry 2013; 52:8286-94. [PMID: 24206272 DOI: 10.1021/bi400842k] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The human cannabinoid receptor, CB1, a G protein-coupled receptor (GPCR), contains a relatively long (∼110 a.a.) amino terminus, whose function is still not defined. Here we explore a potential role for the CB1 N-terminus in modulating ligand binding to the receptor. Although most of the CB1 N-terminus is not necessary for ligand binding, previous studies have found that mutations introduced into its conserved membrane proximal region (MPR) do impair the receptors ability to bind ligand. Moreover, within the highly conserved MPR (∼ residues 90-110) lie two cysteine residues that are invariant in all CB1 receptors. We find these two cysteines (C98 and C107) form a disulfide in heterologously expressed human CB1, and this C98-C107 disulfide is much more accessible to reducing agents than the previously known disulfide in extracellular loop 2 (EL2). Interestingly, the presence of the C98-C107 disulfide modulates ligand binding to the receptor in a way that can be quantitatively analyzed by an allosteric model. The C98-C107 disulfide also alters the effects of allosteric ligands for CB1, Org 27569 and PSNCBAM-1. Together, these results provide new insights into how the N-terminal MPR and EL2 act together to influence the high-affinity orthosteric ligand binding site in CB1 and suggest that the CB1 N-terminal MPR may be an area through which allosteric modulators can act.
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Affiliation(s)
- Jonathan F Fay
- Department of Biochemistry and Molecular Biology, Oregon Health and Science University , Portland, Oregon 97239-3098, United States
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9
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Volume-sensitive anion channels mediate osmosensitive glutathione release from rat thymocytes. PLoS One 2013; 8:e55646. [PMID: 23383255 PMCID: PMC3559474 DOI: 10.1371/journal.pone.0055646] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Accepted: 12/30/2012] [Indexed: 11/19/2022] Open
Abstract
Glutathione (GSH) is a negatively charged tripeptide, which is a major determinant of the cellular redox state and defense against oxidative stress. It is assembled inside and degraded outside the cells and is released under various physiological and pathophysiological conditions. The GSH release mechanism is poorly understood at present. In our experiments, freshly isolated rat thymocytes were found to release GSH under normal isotonic conditions at a low rate of 0.82±0.07 attomol/cell/min and that was greatly enhanced under hypoosomotic stimulation to reach a level of 6.1±0.4 attomol/cell/min. The swelling-induced GSH release was proportional to the cell density in the suspension and was temperature-dependent with relatively low activation energy of 5.4±0.6 kcal/mol indicating a predominant diffusion mechanism of GSH translocation. The osmosensitive release of GSH was significantly inhibited by blockers of volume-sensitive outwardly rectifying (VSOR) anion channel, DCPIB and phloretin. In patch-clamp experiments, osmotic swelling activated large anionic conductance with the VSOR channel phenotype. Anion replacement studies suggested that the thymic VSOR anion channel is permeable to GSH(-) with the permeability ratio P(GSH)/P(Cl) of 0.32 for influx and 0.10 for efflux of GSH. The osmosensitive GSH release was trans-stimulated by SLCO/OATP substrates, probenecid, taurocholic acid and estrone sulfate, and inhibited by an SLC22A/OAT blocker, p-aminohippuric acid (PAH). The inhibition by PAH was additive to the effect of DCPIB or phloretin implying that PAH and DCPIB/phloretin affected separate pathways. We suggest that the VSOR anion channel constitutes a major part of the γ-glutamyl cycle in thymocytes and, in cooperation with OATP-like and OAT-like transporters, provides a pathway for the GSH efflux from osmotically swollen cells.
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10
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Takemoto Y. Pressor response to L-cysteine injected into the cisterna magna of conscious rats involves recruitment of hypothalamic vasopressinergic neurons. Amino Acids 2012; 44:1053-60. [PMID: 23239012 DOI: 10.1007/s00726-012-1440-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Accepted: 11/28/2012] [Indexed: 02/07/2023]
Abstract
The sulfur-containing non-essential amino acid L-cysteine injected into the cisterna magna of adult conscious rats produces an increase in blood pressure. The present study examined if the pressor response to L-cysteine is stereospecific and involves recruitment of hypothalamic vasopressinergic neurons and medullary noradrenergic A1 neurons. Intracisternally injected D-cysteine produced no cardiovascular changes, while L-cysteine produced hypertension and tachycardia in freely moving rats, indicating the stereospecific hemodynamic actions of L-cysteine via the brain. The double labeling immunohistochemistry combined with c-Fos detection as a marker of neuronal activation revealed significantly higher numbers of c-Fos-positive vasopressinergic neurons both in the supraoptic and paraventricular nuclei and tyrosine hydroxylase containing medullary A1 neurons, of L-cysteine-injected rats than those injected with D-cysteine as iso-osmotic control. The results indicate that the cardiovascular responses to intracisternal injection of L-cysteine in the conscious rat are stereospecific and include recruitment of hypothalamic vasopressinergic neurons both in the supraoptic and paraventricular nuclei, as well as of medullary A1 neurons. The findings may suggest a potential function of L-cysteine as an extracellular signal such as neuromodulators in central regulation of blood pressure.
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Affiliation(s)
- Yumi Takemoto
- Neurophysiology, Basic Life Sciences, Institute of Biomedical and Health Sciences, Hiroshima University, Kasumi 1-2-3, Hiroshima 734-8551, Japan.
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11
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Bridges R, Lutgen V, Lobner D, Baker DA. Thinking outside the cleft to understand synaptic activity: contribution of the cystine-glutamate antiporter (System xc-) to normal and pathological glutamatergic signaling. Pharmacol Rev 2012; 64:780-802. [PMID: 22759795 PMCID: PMC3400835 DOI: 10.1124/pr.110.003889] [Citation(s) in RCA: 152] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
System x(c)(-) represents an intriguing target in attempts to understand the pathological states of the central nervous system. Also called a cystine-glutamate antiporter, system x(c)(-) typically functions by exchanging one molecule of extracellular cystine for one molecule of intracellular glutamate. Nonvesicular glutamate released during cystine-glutamate exchange activates extrasynaptic glutamate receptors in a manner that shapes synaptic activity and plasticity. These findings contribute to the intriguing possibility that extracellular glutamate is regulated by a complex network of release and reuptake mechanisms, many of which are unique to glutamate and rarely depicted in models of excitatory signaling. Because system x(c)(-) is often expressed on non-neuronal cells, the study of cystine-glutamate exchange may advance the emerging viewpoint that glia are active contributors to information processing in the brain. It is noteworthy that system x(c)(-) is at the interface between excitatory signaling and oxidative stress, because the uptake of cystine that results from cystine-glutamate exchange is critical in maintaining the levels of glutathione, a critical antioxidant. As a result of these dual functions, system x(c)(-) has been implicated in a wide array of central nervous system diseases ranging from addiction to neurodegenerative disorders to schizophrenia. In the current review, we briefly discuss the major cellular components that regulate glutamate homeostasis, including glutamate release by system x(c)(-). This is followed by an in-depth discussion of system x(c)(-) as it relates to glutamate release, cystine transport, and glutathione synthesis. Finally, the role of system x(c)(-) is surveyed across a number of psychiatric and neurodegenerative disorders.
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Affiliation(s)
- Richard Bridges
- Department of Biomedical and Pharmaceutical Sciences, University of Montana, Missoula, Montana, USA
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12
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Abstract
The activity of many receptors and ion channels in the nervous system can be regulated by redox-dependent mechanisms. Native and recombinant GABA(A) receptors are modulated by endogenous and pharmacological redox agents. However, the sensitivity of GABA(C) receptors to redox modulation has not been demonstrated. We studied the actions of different reducing and oxidizing agents on human homomeric GABArho(1) receptors expressed in Xenopus laevis oocytes. The reducing agents dithiothreitol (2 mM) and N-acetyl-L-cysteine (1 mM) potentiated GABA-evoked Cl(-) currents recorded by two-electrode voltage-clamp, while the oxidants 5-5'-dithiobis-2-nitrobenzoic acid (500 microM) and oxidized dithiothreitol (2 mM) caused inhibition. The endogenous antioxidant glutathione (5 mM) also enhanced GABArho(1) receptor-mediated currents while its oxidized form GSSG (3 mM) had inhibitory effects. All the effects were rapid and easily reversible. Redox modulation of GABArho(1) receptors was strongly dependent on the GABA concentration; dose-response curves for GABA were shifted to the left in the presence of reducing agents, whereas oxidizing agents produced the opposite effect, without changes in the maximal response to GABA and in the Hill coefficient. Our results demonstrate that, similarly to GABA(A) receptors and other members of the cys-loop receptor superfamily, GABA(C) receptors are subjected to redox modulation.
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Affiliation(s)
- Cecilia I Calero
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Facultad de Ciencias Exactas y Naturales Universidad de Buenos Aires (UBA), Ciudad Autónoma de Buenos Aires, Argentina
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YAMANE H, ASECHI M, TSUNEYOSHI Y, DENBOW DM, FURUSE M. Central L-cysteine induces sleep, and D-cysteine induces sleep and abnormal behavior during acute stress in neonatal chicks. Anim Sci J 2009; 80:428-32. [DOI: 10.1111/j.1740-0929.2009.00647.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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14
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Erickson JR, Joiner MLA, Guan X, Kutschke W, Yang J, Oddis CV, Bartlett RK, Lowe JS, O'Donnell SE, Aykin-Burns N, Zimmerman MC, Zimmerman K, Ham AJL, Weiss RM, Spitz DR, Shea MA, Colbran RJ, Mohler PJ, Anderson ME. A dynamic pathway for calcium-independent activation of CaMKII by methionine oxidation. Cell 2008; 133:462-74. [PMID: 18455987 DOI: 10.1016/j.cell.2008.02.048] [Citation(s) in RCA: 853] [Impact Index Per Article: 53.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2007] [Revised: 01/02/2008] [Accepted: 02/13/2008] [Indexed: 02/07/2023]
Abstract
Calcium/calmodulin (Ca2+/CaM)-dependent protein kinase II (CaMKII) couples increases in cellular Ca2+ to fundamental responses in excitable cells. CaMKII was identified over 20 years ago by activation dependence on Ca2+/CaM, but recent evidence shows that CaMKII activity is also enhanced by pro-oxidant conditions. Here we show that oxidation of paired regulatory domain methionine residues sustains CaMKII activity in the absence of Ca2+/CaM. CaMKII is activated by angiotensin II (AngII)-induced oxidation, leading to apoptosis in cardiomyocytes both in vitro and in vivo. CaMKII oxidation is reversed by methionine sulfoxide reductase A (MsrA), and MsrA-/- mice show exaggerated CaMKII oxidation and myocardial apoptosis, impaired cardiac function, and increased mortality after myocardial infarction. Our data demonstrate a dynamic mechanism for CaMKII activation by oxidation and highlight the critical importance of oxidation-dependent CaMKII activation to AngII and ischemic myocardial apoptosis.
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Affiliation(s)
- Jeffrey R Erickson
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109, USA
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Janáky R, Dohovics R, Saransaari P, Oja SS. Modulation of [3H]dopamine release by glutathione in mouse striatal slices. Neurochem Res 2007; 32:1357-64. [PMID: 17401648 DOI: 10.1007/s11064-007-9315-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2006] [Accepted: 02/14/2007] [Indexed: 11/24/2022]
Abstract
Glutathione (gamma-glutamylcysteinylglycine, GSH and oxidized glutathione, GSSG), may function as a neuromodulator at the glutamate receptors and as a neurotransmitter at its own receptors. We studied now the effects of GSH, GSSG, glutathione derivatives and thiol redox agents on the spontaneous, K(+)- and glutamate-agonist-evoked releases of [(3)H]dopamine from mouse striatal slices. The release evoked by 25 mM K(+) was inhibited by GSH, S-ethyl-, -propyl-, -butyl- and pentylglutathione and glutathione sulfonate. 5,5'-Dithio-bis-2-nitrobenzoate (DTNB) and L-cystine were also inhibitory, while dithiothreitol (DTT) and L-cysteine enhanced the K(+)-evoked release. Ten min preperfusion with 50 microM ZnCl(2) enhanced the basal unstimulated release but prevented the activation of K(+)-evoked release by DTT. Kainate and 2-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) evoked dopamine release but the other glutamate receptor agonists N-methyl-D-aspartate (NMDA), glycine (1 mM) and trans-1-aminocyclopentane-1,3-dicarboxylate (t-ACPD, 0.5 mM), and the modulators GSH, GSSG, glutathione sulfonate, S-alkyl-derivatives of glutathione, DTNB, cystine, cysteine and DTT (all 1 mM) were without effect. The release evoked by 1 mM glutamate was enhanced by 1 mM GSH, while GSSG, glutathionesulfonate and S-alkyl derivatives of glutathione were generally without effect or inhibitory. NMDA (1 mM) evoked release only in the presence of 1 mM GSH but not with GSSG, other peptides or thiol modulators. L-Cysteine (1 mM) enhanced the glutamate-evoked release similarly to GSH. The activation by 1 mM kainate was inhibited by S-ethyl-, -propyl-, and -butylglutathione and the activation by 0.5 mM AMPA was inhibited by S-ethylglutathione but enhanced by GSSG. Glutathione alone does not directly evoke dopamine release but may inhibit the depolarization-evoked release by preventing the toxic effects of high glutamate, and by modulating the cysteine-cystine redox state in Ca(2+ )channels. GSH also seems to enhance the glutamate-agonist-evoked release via both non-NMDA and NMDA receptors. In this action, the gamma-glutamyl and cysteinyl moieties of glutathione are involved.
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Affiliation(s)
- Réka Janáky
- Brain Research Center, University of Tampere Medical School, Tampere, Finland
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16
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Cho JH, Askwith CC. Potentiation of acid-sensing ion channels by sulfhydryl compounds. Am J Physiol Cell Physiol 2007; 292:C2161-74. [PMID: 17392378 DOI: 10.1152/ajpcell.00598.2006] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The acid-sensing ion channels (ASICs) are voltage-independent ion channels activated by acidic extracellular pH. ASICs play a role in sensory transduction, behavior, and acidotoxic neuronal death, which occurs during stroke and ischemia. During these conditions, the extracellular concentration of sulfhydryl reducing agents increases. We used perforated patch-clamp technique to analyze the impact of sulfhydryls on H(+)-gated currents from Chinese hamster ovary (CHO) cells expressing human ASIC1a (hASIC1a). We found that hASIC1a currents activated by pH 6.5 were increased almost twofold by the sulfhydryl-containing reducing agents dithiothreitol (DTT) and glutathione. DTT shifted the pH-dose response of hASIC1a toward a more neutral pH (pH(0.5) from 6.54 to 6.69) and slowed channel desensitization. The effect of reducing agents on native mouse hippocampal neurons and transfected mouse ASIC1a was similar. We found that the effect of DTT on hASIC1a was mimicked by the metal chelator TPEN, and mutant hASIC1a channels with reduced TPEN potentiation showed reduced DTT potentiation. Furthermore, the addition of DTT in the presence of TPEN did not result in further increases in current amplitude. These results suggest that the effect of DTT on hASIC1a is due to relief of tonic inhibition by transition metal ions. We found that all ASICs examined remained potentiated following the removal of DTT. This effect was reversed by the oxidizing agent DTNB in hASIC1a, supporting the hypothesis that DTT also impacts ASICs via a redox-sensitive site. Thus sulfhydryl compounds potentiate H(+)-gated currents via two mechanisms, metal chelation and redox modulation of target amino acids.
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Affiliation(s)
- Jun-Hyeong Cho
- Dept. of Neuroscience, The Ohio State University, Columbus, OH 43210, USA
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17
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Chu XP, Close N, Saugstad JA, Xiong ZG. ASIC1a-specific modulation of acid-sensing ion channels in mouse cortical neurons by redox reagents. J Neurosci 2006; 26:5329-39. [PMID: 16707785 PMCID: PMC3799800 DOI: 10.1523/jneurosci.0938-06.2006] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2005] [Revised: 04/09/2006] [Accepted: 04/10/2006] [Indexed: 11/21/2022] Open
Abstract
Acid-sensing ion channel (ASIC)-1a, the major ASIC subunit with Ca2+ permeability, is highly expressed in the neurons of CNS. Activation of these channels with resultant intracellular Ca2+ accumulation plays a critical role in normal synaptic plasticity, learning/memory, and in acidosis-mediated glutamate receptor-independent neuronal injury. Here we demonstrate that the activities of ASICs in CNS neurons are tightly regulated by the redox state of the channels and that the modulation is ASIC1a subunit dependent. In cultured mouse cortical neurons, application of the reducing agents dramatically potentiated, whereas the oxidizing agents inhibited the ASIC currents. However, in neurons from the ASIC1 knock-out mice, neither oxidizing agents nor reducing reagents had any effect on the acid-activated current. In Chinese Hamster Ovary cells, redox-modifying agents only affected the current mediated by homomeric ASIC1a, but not homomeric ASIC1b, ASIC2a, or ASIC3. In current-clamp recordings and Ca(2+)-imaging experiments, the reducing agents increased but the oxidizing agents decreased acid-induced membrane depolarization and the intracellular Ca2+ accumulation. Site-directed mutagenesis studies identified involvement of cysteine 61 and lysine 133, located in the extracellular domain of the ASIC1a subunit, in the modulation of ASICs by oxidizing and reducing agents, respectively. Our results suggest that redox state of the ASIC1a subunit is an important factor in determining the overall physiological function and the pathological role of ASICs in the CNS.
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18
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Thio LL, Zhang HX. Modulation of inhibitory glycine receptors in cultured embryonic mouse hippocampal neurons by zinc, thiol containing redox agents and carnosine. Neuroscience 2006; 139:1315-27. [PMID: 16515845 DOI: 10.1016/j.neuroscience.2006.01.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2005] [Revised: 01/04/2006] [Accepted: 01/21/2006] [Indexed: 11/24/2022]
Abstract
Modulation of inhibitory glycine receptors by zinc (Zn(2+)) and endogenous redox agents such as glutathione may alter inhibition in the mammalian brain. Despite the abundance of Zn(2+) in the hippocampus and its ability to modulate glycine receptors, few studies have examined Zn(2+) modulation of hippocampal glycine receptors. Whether redox agents modulate hippocampal glycine receptors also remains unknown. This study examined Zn(2+) and redox modulation of glycine receptor-mediated currents in cultured embryonic mouse hippocampal neurons using whole-cell recordings. Zn(2+) concentrations below 10 microM potentiated currents elicited by low glycine, beta-alanine, and taurine concentrations by 300-400%. Zn(2+) concentrations above 300 microM produced nearly complete inhibition. Potentiating Zn(2+) concentrations shifted the dose-response curves for the three agonists to the left and decreased the Hill coefficient for glycine and beta-alanine but not taurine. Inhibiting Zn(2+) concentrations shifted the dose-response curves for glycine and beta-alanine to the right but reduced the maximum taurine response. Histidine residues may participate in potentiation because diethyl pyrocarbonate and pH 5.4 diminished Zn(2+) enhancement of glycine currents. pH 5.4 diminished Zn(2+) block of glycine currents, but diethyl pyrocarbonate did not. These findings indicate that separate sites mediate Zn(2+) potentiation and inhibition. The redox agents glutathione, dithiothreitol, tris(2-carboxyethyl)phosphine, and 5,5'-dithiobis(2-nitrobenzoic acid) did not alter glycine currents by a redox mechanism. However, glutathione and dithiothreitol interfered with the effects of Zn(2+) on glycine currents by chelating it. Carnosine had similar effects. Thus, Zn(2+) and thiol containing redox agents that chelate Zn(2+) modulate hippocampal glycine receptors with the mechanism of Zn(2+) modulation being agonist dependent.
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Affiliation(s)
- L L Thio
- Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA.
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Steullet P, Neijt HC, Cuénod M, Do KQ. Synaptic plasticity impairment and hypofunction of NMDA receptors induced by glutathione deficit: Relevance to schizophrenia. Neuroscience 2006; 137:807-19. [PMID: 16330153 DOI: 10.1016/j.neuroscience.2005.10.014] [Citation(s) in RCA: 140] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2005] [Revised: 09/27/2005] [Accepted: 10/07/2005] [Indexed: 11/23/2022]
Abstract
Increasing evidence suggests that the metabolism of glutathione, an endogenous redox regulator, is abnormal in schizophrenia. Patients show a deficit in glutathione levels in the cerebrospinal fluid and prefrontal cortex and a reduction in gene expression of the glutathione synthesizing enzymes. We investigated whether such glutathione deficit altered synaptic transmission and plasticity in slices of rat hippocampus, with particular emphasis on NMDA receptor function. An approximately 40% decrease in brain glutathione levels was induced by s.c. administration of L-buthionine-(S,R)-sulfoximine, an inhibitor of glutathione synthesis. Such glutathione deficit did not affect the basal synaptic transmission, but produced several NMDA receptor-dependent and -independent effects. Glutathione deficit caused an increase in excitability of CA1 pyramidal cells. The paired-pulse facilitation was diminished in glutathione-depleted slices, in a manner that was independent of NMDA receptor activity. This suggests that lowering glutathione levels altered presynaptic mechanisms involved in neurotransmitter release. NMDA receptor-dependent long-term potentiation induced by high-frequency stimulation was impaired in glutathione-depleted slices. Pharmacologically isolated NMDA receptor-mediated field excitatory postsynaptic potentials were significantly smaller in L-buthionine-(S,R)-sulfoximine-treated than in control slices. Hypofunction of NMDA receptors under glutathione deficit was explained at least in part by an excessive oxidation of the extracellular redox-sensitive sites of the NMDA receptors. These results indicate that a glutathione deficit, like that observed in schizophrenics, alters short- and long-term synaptic plasticity and affects NMDA receptor function. Thus, glutathione deficit could be one causal factor for the hypofunction of NMDA receptors in schizophrenia.
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Affiliation(s)
- P Steullet
- Center for Psychiatric Neurosciences, Department of Adult Psychiatry, University Medical Center, University of Lausanne, 1008 Prilly, Switzerland.
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20
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Chang P, Cheng E, Brooke S, Sapolsky R. Marked differences in the efficacy of post-insult gene therapy with catalase versus glutathione peroxidase. Brain Res 2005; 1063:27-31. [PMID: 16257394 DOI: 10.1016/j.brainres.2005.09.032] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2005] [Revised: 09/07/2005] [Accepted: 09/25/2005] [Indexed: 12/19/2022]
Abstract
It is now recognized that the generation of reactive oxygen species (ROS) following necrotic neurological insults plays a central role in the subsequent neuron death. A key step in ROS detoxification is the conversion of hydrogen peroxide to water and oxygen by either catalase (CAT) or glutathione peroxidase (GPX). We have previously shown that overexpression of CAT or GPX protects cultured neurons against subsequent excitotoxic insults. Because of the unpredictability of most acute neurological insults, gene therapy will most often need to be carried out after rather than in anticipation of an insult. Thus, we have tested whether herpes virus amplicon vectors expressing CAT or GPX still protect cultured hippocampal neurons from oxygen/glucose deprivation if introduced following an insult. CAT-expressing vectors were protective even when introduced 8 h post-insult. In contrast, there was no post-insult time window in which GPX overexpression protected. While CAT requires no cofactor, GPX action requires glutathione as a cofactor. Thus, we speculated that the post-insult decline in glutathione compromises the protective potential of GPX. Supporting this, reversing the post-insult glutathione decline with glutathione supplementation was neuroprotective.
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Affiliation(s)
- Pearl Chang
- Departments of Biological Sciences, Neurology, and Neurological Sciences, Stanford University, Gilbert Laboratory, MC 5020, Stanford, CA 94305-5020, USA
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21
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Lorenc-Koci E, Gołembiowska K, Wardas J. 1,2,3,4-Tetrahydroisoquinoline protects terminals of dopaminergic neurons in the striatum against the malonate-induced neurotoxicity. Brain Res 2005; 1051:145-54. [PMID: 16004976 DOI: 10.1016/j.brainres.2005.06.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2005] [Revised: 05/31/2005] [Accepted: 06/05/2005] [Indexed: 11/21/2022]
Abstract
Malonate, a reversible inhibitor of the mitochondrial enzyme succinate dehydrogenase, is frequently used as a model neurotoxin to produce lesion of the nigrostriatal dopaminergic system in animals due to particular sensitivity of dopamine neurons to mild energy impairment. This model of neurotoxicity was applied in our study to explore neuroprotective potential of 1,2,3,4-tetrahydroisoquinoline (TIQ), an endo- and exogenous substance whose function in the mammalian brain, despite extensive studies, has not been elucidated so far. Injection of malonate at a dose of 3 mumol unilaterally into the rat left medial forebrain bundle resulted in the 54% decrease in dopamine (DA) concentration in the ipsilateral striatum and, depending on the examined striatum regions, caused 24-44% reduction in [3H]GBR12,935 binding to the dopamine transporter (DAT). TIQ (50 mg/kg i.p.) administered 4 h before malonate infusion and next once daily for successive 7 days prevented both these effects of malonate. Such TIQ treatment restored DA content and DAT binding almost to the control level. The results of the present study indicate that TIQ may act as a neuroprotective agent in the rat brain. An inhibition of the enzymatic activities of monoamine oxidase and gamma-glutamyl transpeptidase as well as an increase in the striatal levels of glutathione and nitric oxide found after TIQ administration and reported in our earlier studies are considered to be potential factors that may be involved in the TIQ-mediated protection of dopamine terminals from malonate toxicity.
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Affiliation(s)
- Elzbieta Lorenc-Koci
- Department of Neuropsychopharmacology, Institute of Pharmacology, Polish Academy of Sciences, 12, Smetna Street, PL-31-343 Kraków, Poland
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22
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Andrey F, Tsintsadze T, Volkova T, Lozovaya N, Krishtal O. Acid sensing ionic channels: modulation by redox reagents. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2005; 1745:1-6. [PMID: 16085050 DOI: 10.1016/j.bbamcr.2005.01.008] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2004] [Revised: 01/20/2005] [Accepted: 01/31/2005] [Indexed: 10/25/2022]
Abstract
Acid-sensing ion channels (ASICs) are widely expressed in mammalian sensory neurons and supposedly play a role in nociception and acid sensing. In the course of functioning the redox status of the tissue is subjected to changes. Using whole-cell patch-clamp/concentration clamp techniques we have investigated the effect of redox reagents on the ASIC-like currents in the sensory ganglia and hippocampal neurons of rat. The reducing agent dithiothreitol (DTT), when applied in the concentrations 1-2 mM, reversibly potentiates proton-activated currents, while the oxidizing reagent 5,5'-dithio-bis-(2-nitrobenzoic acid) (DTNB) causes their inhibition. The EC50 and Hill coefficient for the activation of ASIC-like currents by protons are not affected by DTT. Redox modulation of proton-activated currents is independent on the membrane potential and on the level of pH used for the current activation. The endogenous antioxidant tripeptide glutathione (its reduced form, g-l-glutamyl-l-cysteinyl-glycine, GSH) also potentiates proton-activated currents. Our results indicate that ASIC-like currents are susceptible to regulation by redox agents.
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Affiliation(s)
- Fedorenko Andrey
- Department of Cellular Membranology, Bogomoletz Institute of Physiology, Kiev, Ukraine
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23
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Jacobsen JPR, Rodriguiz RM, Mørk A, Wetsel WC. Monoaminergic dysregulation in glutathione-deficient mice: Possible relevance to schizophrenia? Neuroscience 2005; 132:1055-72. [PMID: 15857710 DOI: 10.1016/j.neuroscience.2005.01.059] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2004] [Revised: 01/19/2005] [Accepted: 01/28/2005] [Indexed: 11/22/2022]
Abstract
Several lines of research have implicated glutathione (GSH) in schizophrenia. For instance, GSH deficiency has been reported in the prefrontal cortex of schizophrenics in vivo. Further, in rats postnatal GSH-deficiency combined with hyperdopaminergia led to cognitive impairments in the adult. In the present report we studied the effects of 2-day GSH-deficiency with L-buthionine-(S,R)-sulfoximine on monoaminergic function in mice. The effect of GSH-deficiency per se and when combined with the amphetamine and phencyclidine (PCP) models of schizophrenia was investigated. GSH-deficiency significantly altered tissue levels of dopamine (DA), 5-hydroxytryptamine (5-HT) and their respective metabolites homovanillic acid (HVA), and 5-hydroxyindoleacetic acid (5-HIAA) in a region-specific fashion. The effects of GSH-deficiency on tissue monoamines were distinct from and, generally, did not interact with the effects of amphetamine (5 mg/kg; i.p.) on tissue monoamines. Microdialysis studies showed that extracellular DA-release after amphetamine (5 mg/kg, i.p.) was two-fold increased in the nucleus accumbens of GSH-deficient mice as compared with control mice. Basal DA was unaltered. Further, extracellular levels of HVA in the frontal cortex and hippocampus and 5-HIAA in the nucleus accumbens were elevated by GSH-deficiency per se. Spontaneous locomotor activity in the open field was unchanged in GSH-deficient mice. In contrast, GSH-deficiency modulated the locomotor responses to mid-range doses of amphetamine (1.5 and 5 mg/kg, i.p.). Further, GSH-deficient mice displayed an increased locomotor response to low (2 and 3 mg/kg, i.p.) doses of phencyclidine (PCP). In conclusion, the data presented here show that even short-term GSH-deficiency has consequences for DA and 5-HT function. This was confirmed on both neurochemical and behavioral levels. How GSH and the monoamines interact needs further scrutiny. Moreover, the open field findings suggest reduced or altered N-methyl-d-aspartate (NMDA) receptor function in GSH-deficient mice. Thus, GSH-deficiency can lead to disturbances in DA, 5-HT and NMDA function, a finding that may have relevance for schizophrenia.
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Affiliation(s)
- J P R Jacobsen
- Department of Psychiatry and Behavioral Sciences, Cell Biology and Medicine (Endocrinology), Mouse Behavioral and Neuroendocrine Analysis Core Facility, Duke University Medical Center, Durham, NC 27710, USA.
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Abstract
Many proteins present on cell surfaces and located in extracellular fluids contain cysteine and methionine residues that are subject to oxidation. These proteins, which include transporters, receptors, and enzymes, respond to variations in the extracellular thiol/disulfide redox environment. Changes in activity of these proteins can alter the ability of organs to function normally and influence processes such as nutritional absorption, secretory function, neurotransmission, and susceptibility to toxicants. In addition, extracellular redox can regulate tissue homeostasis through effects on cell proliferation, differentiation, apoptosis, and immune function. Consequently, extracellular redox can have important influences on health status and disease states and thus could be a target for nutritional interventions.
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Abstract
The time-dependent brain damage induced in adult rats by a single dose of L-cysteine was examined morphologically. Five-week-old male Sprague-Dawley rats that received 1500 mg/kg of L-cysteine by intraperitoneal injection were examined at 12 and 24 h and 3, 7, and 14 days after administration. Pathological changes were seen in the cerebral and cerebellar cortex. Neuronal karyopyknosis was observed in the granular and molecular layers of the superficial cerebellar cortex at 12 h, and well-demarcated infarct-like lesions were seen with a widespread distribution in the cerebral cortex at 24 h. A large number of lipid phagocytes and glial cell proliferation were noted in the affected regions on days 3 to 14. The neuronal cell death observed in the cerebellar granular layer cells was demonstrated to be due to apoptosis by histopathological and ultrastructural examinations as well as by the terminal deoxyribonucleotide transferase-mediated dUTP nick-end labeling (TUNEL) method and agarose gel electrophoresis for DNA laddering. It was found that L-cysteine induced brain lesions mainly in the cerebral and cerebellar cortex in adult rats, in contrast to lesions in various regions as observed in neonatal rats. The histopathological findings reported here suggest that the pathogenesis of the brain damage induced by L-cysteine in adult rats differs from that in neonatal rats. It appears likely that L-cysteine-induced brain damage is secondary to impairment of blood flow or other unknown factors that are responsible for the subsequent development of brain lesions.
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Affiliation(s)
- Osamu Sawamoto
- Drug Safety and Metabolism, Otsuka Pharmaceutical Factory Inc, Muya-cho, Naruto, Tokushima 772-8601, Japan.
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Ehrhart J, Zeevalk GD. Cooperative interaction between ascorbate and glutathione during mitochondrial impairment in mesencephalic cultures. J Neurochem 2003; 86:1487-97. [PMID: 12950457 DOI: 10.1046/j.1471-4159.2003.01954.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A decrease in total glutathione, and aberrant mitochondrial bioenergetics have been implicated in the pathogenesis of Parkinson's disease. Our previous work exemplified the importance of glutathione (GSH) in the protection of mesencephalic neurons exposed to malonate, a reversible inhibitor of mitochondrial succinate dehydrogenase/complex II. Additionally, reactive oxygen species (ROS) generation was an early, contributing event in malonate toxicity. Protection by ascorbate was found to correlate with a stimulated increase in protein-glutathione mixed disulfide (Pr-SSG) levels. The present study further examined ascorbate-glutathione interactions during mitochondrial impairment. Depletion of GSH in mesencephalic cells with buthionine sulfoximine potentiated both the malonate-induced toxicity and generation of ROS as monitored by dichlorofluorescein diacetate (DCF) fluorescence. Ascorbate completely ameliorated the increase in DCF fluorescence and toxicity in normal and GSH-depleted cultures, suggesting that protection by ascorbate was due in part to upstream removal of free radicals. Ascorbate stimulated Pr-SSG formation during mitochondrial impairment in normal and GSH-depleted cultures to a similar extent when expressed as a proportion of total GSH incorporated into mixed disulfides. Malonate increased the efflux of GSH and GSSG over time in cultures treated for 4, 6 or 8 h. The addition of ascorbate to malonate-treated cells prevented the efflux of GSH, attenuated the efflux of GSSG and regulated the intracellular GSSG/GSH ratio. Maintenance of GSSG/GSH with ascorbate plus malonate was accompanied by a stimulation of Pr-SSG formation. These findings indicate that ascorbate contributes to the maintenance of GSSG/GSH status during oxidative stress through scavenging of radical species, attenuation of GSH efflux and redistribution of GSSG to the formation of mixed disulfides. It is speculated that these events are linked by glutaredoxin, an enzyme shown to contain both dehydroascorbate reductase as well as glutathione thioltransferase activities.
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Affiliation(s)
- Julie Ehrhart
- Department of Neurology, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, Piscataway, New Jersey, USA
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Goldstein L, Teng ZP, Zeserson E, Patel M, Regan RF. Hemin induces an iron-dependent, oxidative injury to human neuron-like cells. J Neurosci Res 2003; 73:113-21. [PMID: 12815715 DOI: 10.1002/jnr.10633] [Citation(s) in RCA: 115] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Hemin is released from hemoglobin after CNS hemorrhage and is present at high micromolar concentrations in intracranial hematomas. This highly reactive compound is potentially cytotoxic via a variety of oxidative and nonoxidative mechanisms. However, despite its clinical relevance, little is known of its effect on neuronal cells. In this study, we tested the hypotheses that hemin is toxic to human neurons at physiologically relevant concentrations and that its toxicity is iron dependent and oxidative. A homogeneous population of neuron-like cells was produced by sequential treatment of SH-SY5Y cells with retinoic acid and brain-derived neurotrophic factor, using the protocol of Encinas et al. Hemin exposure for 24 hr resulted in cell death that progressively increased between 3 and 30 microM (EC(50) approximately 10 microM); protoporphyrin IX, the iron-free congener of hemin, was not toxic. Cell death commenced at 14 hr and was preceded by a marked increase in cellular reactive oxygen species (ROS). Most injury and ROS production were prevented by concomitant treatment with an equimolar concentration of the lipid-soluble iron chelator phenanthroline; the water-soluble chelator deferoxamine was also effective at concentrations of 0.1 mM or higher. Heme oxygenase-2 was constitutively expressed by these cells, and heme oxygenase-1 was induced by hemin. Heme oxygenase inhibition attenuated ROS generation and reduced injury by about one-third. Cell death was also prevented with the sulfhydryl reducing agents glutathione and mercaptoethanol. Nuclear morphology in the hours prior to cell lysis revealed a predominantly homogenous staining pattern; the percentage of fragmented nuclei was increased only at 4 hr and then accounted for only 1.45% +/- 0.25% of cells. The general caspase inhibitor zVAD-fmk had no effect on cell viability. These results suggest that hemin is toxic to human neuron-like cells at concentrations that are less than 3% of those observed in intracranial hematomas. In this model, its toxicity is iron dependent, oxidative, and predominantly necrotic.
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Affiliation(s)
- Laurel Goldstein
- Department of Emergency Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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Abstract
The antioxidant glutathione (GSH) is essential for the cellular detoxification of reactive oxygen species in brain cells. A compromised GSH system in the brain has been connected with the oxidative stress occuring in neurological diseases. Recent data demonstrate that besides intracellular functions GSH has also important extracellular functions in brain. In this respect astrocytes appear to play a key role in the GSH metabolism of the brain, since astroglial GSH export is essential for providing GSH precursors to neurons. Of the different brain cell types studied in vitro only astrocytes release substantial amounts of GSH. In addition, during oxidative stress astrocytes efficiently export glutathione disulfide (GSSG). The multidrug resistance protein 1 participates in both the export of GSH and GSSG from astrocytes. This review focuses on recent results on the export of GSH and GSSG from brain cells as well as on the functions of extracellular GSH in the brain. In addition, implications of disturbed GSH pathways in brain for neurodegenerative diseases will be discussed.
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Affiliation(s)
- Ralf Dringen
- Physiologisch-Chemisches Institut der Universität Tübingen, Hoppe-Seyler-Str. 4, D-72076 Tübingen, Germany
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Tretter L, Répássy R, Adam-Vizi V. Endogenous glutamate contributes to the maintenance of glutathione level under oxidative stress in isolated nerve terminals. Neurochem Int 2003; 42:393-400. [PMID: 12510022 DOI: 10.1016/s0197-0186(02)00140-7] [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: 10/27/2022]
Abstract
Exposure of isolated nerve terminals to hydrogen peroxide (25-500 microM) for 10 min produced a partially reversible decrease in the total and reduced glutathione level. No release and resynthesis of glutathione by the oxidant was involved in this effect. Loss of reduced glutathione was associated with elimination of H(2)O(2), which was very quick with >70% of the oxidant eliminated within 5 min. Recovery of both total and reduced glutathione was pronounced after 10 min when the majority of H(2)O(2) was eliminated. Previously we have reported that glutamate metabolism under oxidative stress contributes to the operation of the Krebs cycle, thus to the production of NAD(P)H [J. Neurosci. 20 (2000) 8972]. In the present study we addressed whether metabolism of endogenous glutamate plays a role in the maintenance of glutathione level in nerve terminals. Glutamine and beta-hydroxybutyrate (5mM), alternative metabolites in synaptosomes, were able to decrease the loss of total and reduced glutathione induced by hydrogen peroxide. Metabolic consumption of glutamate was reduced at the same time. In addition an increased demand on the glutathione system by the catalase inhibitor aminotriazole augmented the metabolic consumption of glutamate. It is concluded that under oxidative stress glutamate metabolism contributes to the maintenance of glutathione level, thus to the antioxidant capacity of nerve terminals.
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Affiliation(s)
- Laszlo Tretter
- Neurochemical Group, Department of Medical Biochemistry, Semmelweis University of Medicine, P.O. Box 262, Budapest H-1444, Hungary
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Wallin C, Abbas AK, Tranberg M, Weber SG, Wigström H, Sandberg M. Searching for mechanisms of N-methyl-D-aspartate-induced glutathione efflux in organotypic hippocampal cultures. Neurochem Res 2003; 28:281-91. [PMID: 12608701 PMCID: PMC1475825 DOI: 10.1023/a:1022381318126] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
N-Methyl-D-aspartate (NMDA)-receptor stimulation evoked a selective and partly delayed elevated efflux of glutathione, phosphoethanolamine, and taurine from organotypic rat hippocampus slice cultures. The protein kinase inhibitors H9 and staurosporine had no effect on the efflux. The phospholipase A2 inhibitors quinacrine and 4-bromophenacyl bromide, as well as arachidonic acid, a product of phospholipase A2 activity, did not affect the stimulated efflux. Polymyxin B, an antimicrobal agent that inhibits protein kinase C, and quinacrine in high concentration (500 microM), blocked efflux completely. The stimulated efflux after but not during NMDA incubation was attenuated by a calmodulin antagonist (W7) and an anion transport inhibitor (DNDS). Omission of calcium increased the spontaneous efflux with no or small additional effects by NMDA. In conclusion, NMDA receptor stimulation cause an increased selective efflux of glutathione, phosphoethanolamine and taurine in organotypic cultures of rat hippocampus. The efflux may partly be regulated by calmodulin and DNDS sensitive channels.
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Affiliation(s)
- Camilla Wallin
- Department of Medical Biophysics, University of Göteborg, Medicinaregatan 11, S-405 30 Göteborg, Sweden
| | - Abdul-Karim Abbas
- Department of Medical Biophysics, University of Göteborg, Medicinaregatan 11, S-405 30 Göteborg, Sweden
| | - Mattias Tranberg
- Department of Medical Biophysics, University of Göteborg, Medicinaregatan 11, S-405 30 Göteborg, Sweden
| | - Stephen G. Weber
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - Holger Wigström
- Department of Medical Biophysics, University of Göteborg, Medicinaregatan 11, S-405 30 Göteborg, Sweden
| | - Mats Sandberg
- Department of Medical Biophysics, University of Göteborg, Medicinaregatan 11, S-405 30 Göteborg, Sweden
- Address reprint requests to: Mats Sandberg, Tel: (46)-31-7733395; Fax: (46)-31-7733558; E-mail:
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Jiang XR, Dryhurst G. Inhibition of the alpha-ketoglutarate dehydrogenase and pyruvate dehydrogenase complexes by a putative aberrant metabolite of serotonin, tryptamine-4,5-dione. Chem Res Toxicol 2002; 15:1242-7. [PMID: 12387620 DOI: 10.1021/tx020029b] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A transient energy impairment with resultant release and subsequent reuptake of 5-hydroxytryptamine (5-HT) and NMDA receptor activation with consequent cytoplasmic superoxide (O(2)(-)(*)), nitric oxide (NO(*)), and peroxynitrite (ONOO(-)) generation have all been implicated in a neurotoxic cascade which ultimately leads to the degeneration of serotonergic neurons evoked by methamphetamine (MA) and 3,4-methylenedioxymethamphetamine (MDMA). Such observations raise the possibility that the O(2)(-)(*)/NO(*)/ONOO(-)-mediated oxidation of 5-HT, as it returns via the plasma membrane transporter to the cytoplasm of serotonergic neurons when the MA/MDMA-induced energy impairment begins to subside, may generate an endogenous neurotoxin. In vitro the O(2)(-)(*)/NO(*)/ONOO(-)-mediated oxidation of 5-HT forms tryptamine-4,5-dione (T-4,5-D). When incubated with intact rat brain mitochondria, T-4,5-D strongly inhibits state 3 respiration with pyruvate or alpha-ketoglutarate as substrates at concentrations which do not affect succinate-supported (complex II) respiration. Experiments with freeze-thawed rat brain mitochondria reveal that T-4,5-D inhibits the pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase complexes. These and other properties of T-4,5-D raise the possibility that it may be an endogenously formed intraneuronal metabolite of 5-HT that contributes to the serotonergic neurotoxicity of MA and MDMA.
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Affiliation(s)
- Xiang-Rong Jiang
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma 73019, USA
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Hirrlinger J, Schulz JB, Dringen R. Glutathione release from cultured brain cells: multidrug resistance protein 1 mediates the release of GSH from rat astroglial cells. J Neurosci Res 2002; 69:318-26. [PMID: 12125073 DOI: 10.1002/jnr.10308] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
To investigate the release of glutathione (GSH) from brain cells, cultures enriched for astroglial cells, neurons, oligodendroglial cells, and microglial cells derived from rat brain were studied. During incubation of astroglial cultures, GSH accumulated in the medium with a rate of 3.1 +/- 0.6 nmol x h(-1) x mg protein(-1). In contrast, only marginal amounts of extracellular GSH were detectable in the media of the other brain cell cultures investigated. The mechanism of GSH release from astroglial cells, as yet, has not been reported. Multidrug resistance protein 1 (Mrp1), a transport protein known to mediate cellular export of glutathione disulfide and glutathione conjugates, is expressed in astroglial cultures. Inhibitors of Mrp1 were used to test for a function of this transporter in mediating GSH release from astroglial cells. The presence of the competitive Mrp1 inhibitor MK571 at a concentration of 50 microM inhibited the rate of GSH release by 63%. In contrast, the low concentration of 1 microM of MK571 increased the rate of GSH release by 83%. This bimodal concentration-dependent effect of MK571 is in accord with literature data for the effects of Mrp1 substrates on GSH release from cells. In addition, the presence of cyclosporin A (10 microM) reduced the GSH release rate significantly and completely blocked the stimulating effect of 1 microM MK571 on the release of GSH from astroglial cells. In conclusion, the data presented are a strong indication that Mrp1 participates in the release of GSH from astroglial cells.
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Hirrlinger J, Schulz JB, Dringen R. Effects of dopamine on the glutathione metabolism of cultured astroglial cells: implications for Parkinson's disease. J Neurochem 2002; 82:458-67. [PMID: 12153471 DOI: 10.1046/j.1471-4159.2002.01013.x] [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: 11/20/2022]
Abstract
To investigate the effects of dopamine (DA) on the release of glutathione (GSH) from astrocytes, we used astroglia-rich primary cultures from the brains of newborn rats. In the absence of DA, GSH accumulated in the medium of these cultures with a constant rate. In contrast, during incubation of the cells with 50 micro m DA extracellular GSH was not detectable anymore. This disappearance of extracellular GSH was prevented by superoxide dismutase, indicating that DA does not affect GSH release but rather reacts with the released GSH in a superoxide-dependent reaction. Incubation of astroglial cultures with 0.5 and 1 mm DA established almost constant extracellular concentrations of H2O2 of 5 microm and 15 microm, respectively. Under these conditions astroglial cultures release glutathione disulphide (GSSG). This GSSG export was blocked by catalase and by MK571, an inhibitor of the multidrug resistance protein 1. The effects of DA on the extracellular accumulations of GSH and GSSG were not modulated by inhibitors of DA receptors, DA transport, and monoamine oxidases. The other catecholamines adrenaline and noradrenaline showed similar effects on the accumulation of GSH and GSSG in the medium compared with those obtained for DA. In conclusion, the data presented demonstrate that DA affects astroglial GSH metabolism by two mechanisms: (i) directly by chemical reaction with extracellular GSH, and (ii) indirectly by generation of hydrogen peroxide that leads to the efflux of GSSG from astroglial cells. These observations are discussed in the context of the brain's GSH metabolism in Parkinson's disease.
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Dryhurst G. Are dopamine, norepinephrine, and serotonin precursors of biologically reactive intermediates involved in the pathogenesis of neurodegenerative brain disorders? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2002; 500:373-96. [PMID: 11764972 DOI: 10.1007/978-1-4615-0667-6_61] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Affiliation(s)
- G Dryhurst
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman 73019, USA
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35
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Blin M, Crusio WE, Hévor T, Cloix JF. Chronic inhibition of glutamine synthetase is not associated with impairment of learning and memory in mice. Brain Res Bull 2002; 57:11-5. [PMID: 11827732 DOI: 10.1016/s0361-9230(01)00631-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The convulsant methionine sulfoximine (MSO) is a byproduct of the agenized flour commonly used for feeding domestic animals decades ago. MSO is a powerful glycogenic and epileptogenic agent, and it is an irreversible inhibitor of glutamine synthetase. This latter effect was hypothesized to be responsible for the increase in the incidence of some neuropathologies in humans, such as Alzheimer's disease or Parkinson's disease. In order to test this hypothesis, we chronically administered MSO to two inbred strains of mice, C57BL/6J and BALB/cJ, and analyzed possible alterations in learning and memory features of these mice. Mice were given 20 mg/kg of MSO three times a week for 10 weeks. Spatial learning capabilities assessed with a radial maze were not affected by the long-term MSO treatment, although activity was significantly decreased in BALB/cJ mice. Thus, our data suggest that long-term administration of non-convulsive and non-glycogenic doses of MSO do not alter the spatial memory of mice. Our results do not support the hypothesis that chronic treatment with MSO influences hippocampus-dependent learning abilities in mice.
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Affiliation(s)
- Marion Blin
- Métabolisme Cérébral et Neuropathologies, UPRES EA 2633, Université d'Orléans, Orléans Cedex 2, France
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Wrona MZ, Dryhurst G. A putative metabolite of serotonin, tryptamine-4,5-dione, is an irreversible inhibitor of tryptophan hydroxylase: possible relevance to the serotonergic neurotoxicity of methamphetamine. Chem Res Toxicol 2001; 14:1184-92. [PMID: 11559032 DOI: 10.1021/tx010037c] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Tryptamine-4,5-dione (T-4,5-D) is formed as a result of oxidation of 5-hydroxytryptamine by superoxide (O(2)(-)(*), nitric oxide (NO*), and peroxynitrite (ONOO(-)). T-4,5-D rapidly inactivates tryptophan hydroxylase (TPH), derived from rat brain, probably as a result of covalent modification of active site cysteine residues. The activity of TPH exposed to T-4,5-D cannot be restored by anaerobic reduction with dithiothreitol (DTT) and ferrous iron (Fe(2+)) indicating that the inactivation is irreversible. 7-S-Glutathionyl-tryptamine-4,5-dione, formed by the rapid reaction between T-4,5-D and glutathione, also inhibits TPH but in this case the activity is restored by anaerobic reduction with DTT/Fe(2+). The results of this investigation may be relevant to the initial reversible and subsequent irreversible inactivation of TPH evoked by methamphetamine and 3,4-methylenedioxymethamphetamine.
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Affiliation(s)
- M Z Wrona
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma 73019, USA
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37
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Yoneda Y, Kuramoto N, Kitayama T, Hinoi E. Consolidation of transient ionotropic glutamate signals through nuclear transcription factors in the brain. Prog Neurobiol 2001; 63:697-719. [PMID: 11165002 DOI: 10.1016/s0301-0082(00)00036-8] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Long-lasting alterations of neuronal functions could involve mechanisms associated with consolidation of transient extracellular signals through modulation of de novo synthesis of particular functional proteins in the brain. In eukaryotes, protein de novo synthesis is mainly under the control at the level of gene transcription by transcription factors in the cell nucleus. Transcription factors are nuclear proteins with an ability to recognize particular core nucleotides at the upstream and/or downstream of target genes, and thereby to modulate the activity of RNA polymerase II that is responsible for the formation of mRNA from double stranded DNA. Gel retardation electrophoresis is widely employed for conventional detection of DNA binding activities of a variety of transcription factors with different protein motifs. Extracellular ionotropic glutamate (Glu) signals lead to rapid and selective potentiation of DNA binding of the nuclear transcription factor activator protein-1 (AP1) that is a homo- and heterodimeric complex between Jun and Fos family members, in addition to inducing expression of the corresponding proteins, in a manner unique to each Glu signal in murine hippocampus. Therefore, extracellular Glu signals may be differentially transduced into the nucleus to express AP1 with different assemblies between Jun and Fos family members, and thereby to modulate de novo synthesis of the individual target proteins at the level of gene transcription in the hippocampus. Such mechanisms may be operative on synaptic plasticity as well as delayed neuronal death through consolidation of alterations of a variety of cellular functions induced by transient extracellular signals in the brain.
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Affiliation(s)
- Y Yoneda
- Department of Molecular Pharmacology, Kanazawa University Faculty of Pharmaceutical Sciences, 13-1 Takara-machi, Kanazawa, 920-0934, Ishikawa, Japan.
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Ogita K, Kitayama T, Okuda H, Yoneda Y. Effects of glutathione depletion by 2-cyclohexen-1-one on excitatory amino acids-induced enhancement of activator protein-1 DNA binding in murine hippocampus. J Neurochem 2001; 76:1905-15. [PMID: 11259509 DOI: 10.1046/j.1471-4159.2001.00212.x] [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: 11/20/2022]
Abstract
We have investigated the role of glutathione in mechanisms associated with excitatory amino acid signaling to the nuclear transcription factor activator protein-1 (AP1) in the brain using mice depleted of endogenous glutathione by prior treatment with 2-cyclohexen-1-one (CHX). In the hippocampus of animals treated with CHX 2 h before, a significant increase was seen in enhancement of AP1 DNA binding when determined 2 h after the injection of kainic acid (KA) at low doses. The sensitization to KA was not seen in animals injected with CHX 24 h before, in coincidence with the recovery of glutathione contents to the normal levels. By contrast, CHX did not significantly affect the potentiation by NMDA of AP1 binding under any experimental conditions. Prior treatment with CHX resulted in facilitation of behavioral changes induced by KA without affecting those induced by NMDA. These results suggest that endogenous glutathione may be at least in part involved in molecular mechanisms underlying transcriptional control by KA, but not by NMDA, signals of cellular functions.
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Affiliation(s)
- K Ogita
- Department of Pharmacology, Setsunan University, Hirakata, Osaka, Japan.
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39
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Regan RF, Guo Y. Magnesium deprivation decreases cellular reduced glutathione and causes oxidative neuronal death in murine cortical cultures. Brain Res 2001; 890:177-83. [PMID: 11164781 DOI: 10.1016/s0006-8993(00)03156-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The vulnerability of cultured cortical neurons to oxidative injury is an inverse function of the extracellular Mg2+ concentration. In order to test the hypothesis that depolarization-enhanced release of reduced glutathione (GSH) contributes to this phenomenon, we assessed the effect of Mg2+ deprivation on cellular and medium glutathione levels. Incubation of mixed neuronal and glial cultures in Mg2+-free medium resulted in a decline in cellular total glutathione (GSx) within 8 h, without change in oxidized glutathione (GSSG); no effect was seen in pure glial cultures. This decrease in cellular GSx was associated with a progressive increase in GSx but not GSSG in the culture medium. Cellular GSH loss was not attenuated by concomitant treatment with antioxidants (ascorbate, Trolox, or deferoxamine), but was prevented by the NMDA receptor antagonist MK-801. Mg2+ deprivation for over 24 h produced neuronal but not glial death, with release of about 40% of neuronal lactate dehydrogenase by 48-60 h. Most of this cytotoxicity was prevented by treatment with either antioxidants or MK-801. These results suggest that Mg2+ deprivation causes release of neuronal reduced glutathione via a mechanism involving excessive NMDA receptor activation. If prolonged, cellular GSH depletion ensues, leading to oxidative neuronal death.
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Affiliation(s)
- R F Regan
- Department of Surgery, Division of Emergency Medicine, Thomas Jefferson University, 1020 Sansom Street, 239 Thompson Building, Philadelphia, PA 19107, USA.
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40
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Influence of glutathione on the oxidation chemistry of 5-S-cysteinyldopamine: potentially neuroprotective reactions of relevance to Parkinson's disease. Tetrahedron 2001. [DOI: 10.1016/s0040-4020(00)00953-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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41
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Gu L, Miller KE, Dryhurst G. Nigrostriatal dopaminergic neurotoxicity of L-cysteine after stereotaxic administration into the substantia nigra of rats: Potential implications for MPTP-induced neurotoxicity and parkinson’s disease. Neurotox Res 2000. [DOI: 10.1007/bf03033344] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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42
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Abstract
The tripeptide glutathione is the thiol compound present in the highest concentration in cells of all organs. Glutathione has many physiological functions including its involvement in the defense against reactive oxygen species. The cells of the human brain consume about 20% of the oxygen utilized by the body but constitute only 2% of the body weight. Consequently, reactive oxygen species which are continuously generated during oxidative metabolism will be generated in high rates within the brain. Therefore, the detoxification of reactive oxygen species is an essential task within the brain and the involvement of the antioxidant glutathione in such processes is very important. The main focus of this review article will be recent results on glutathione metabolism of different brain cell types in culture. The glutathione content of brain cells depends strongly on the availability of precursors for glutathione. Different types of brain cells prefer different extracellular glutathione precursors. Glutathione is involved in the disposal of peroxides by brain cells and in the protection against reactive oxygen species. In coculture astroglial cells protect other neural cell types against the toxicity of various compounds. One mechanism for this interaction is the supply by astroglial cells of glutathione precursors to neighboring cells. Recent results confirm the prominent role of astrocytes in glutathione metabolism and the defense against reactive oxygen species in brain. These results also suggest an involvement of a compromised astroglial glutathione system in the oxidative stress reported for neurological disorders.
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Affiliation(s)
- R Dringen
- Physiologisch-chemisches Institut der Universität, Hoppe-Seyler-Str. 4, D-72076 Tübingen, Germany.
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43
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Salt TE, Zhang H, Mayer B, Benz B, Binns KE, Do KQ. Novel mode of nitric oxide neurotransmission mediated via S-nitroso-cysteinyl-glycine. Eur J Neurosci 2000; 12:3919-25. [PMID: 11069587 DOI: 10.1046/j.1460-9568.2000.00285.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
S-nitroso-cysteinyl-glycine, a novel nitric oxide-adduct thiol compound, can be detected in the brain (2.3+/-0.6 pmol/mg protein), and released following stimulation of sensory afferents to the rat ventrobasal thalamus in vivo (resting conditions 17 nM; stimulation: 186 nM). Iontophoretic application of CysNOGly (20-80 nA) onto thalamic neurons in vivo resulted in enhancements of excitatory responses to either NMDA or AMPA (182+/-13.6% and 244+/-27.8% of control values, n = 15). CysNOGly enhanced responses to stimulation of vibrissal afferents to 132+/-2.2% (n = 7) of control values. In contrast, the dipeptide CysGly reduced responses of ventrobasal neurons to NMDA and AMPA (54+/-8.4% and 55+/-10.8% of control, n = 5). CysNOGly was also a potent activator of soluble guanylate cyclase in vitro. Moreover, we found that NMDA elevated CysNOGly levels in vitro and this stimulatory effect was reduced by inhibitors of the neuronal NO synthase and of the gamma-glutamyl transpeptidase, suggesting that production of NO and CysGly is a prelude to CysNOGly synthesis. These findings suggest that the nitrosothiol CysNOGly plays a role in synaptic transmission in the ventrobasal thalamus. We propose a novel synaptic buffering mechanism where S-nitroso-cysteinyl-glycine serves to restrict the locus of action of nitric oxide and so increase its local availability for target delivery. This could lead to a change in neuronal responses favouring sensory transmission similar to that seen in wakefulness or arousal in order to locally enhance transmission of persistent sensory stimuli.
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Affiliation(s)
- T E Salt
- Department of Visual Science, Institute of Ophthalmology, University College London, London EC1V 9EL, UK.
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Abstract
We review here the possible mechanisms of neuronal degeneration caused by L-cysteine, an odd excitotoxin. L-Cysteine lacks the omega carboxyl group required for excitotoxic actions via excitatory amino acid receptors, yet it evokes N-methyl-D-aspartate (NMDA) -like excitotoxic neuronal death and potentiates the Ca2+ influx evoked by NMDA. Both actions are prevented by NMDA antagonists. One target for cysteine effects is thus the NMDA receptor. The following mechanisms are discussed now: (1) possible increase in extracellular glutamate via release or inhibition of uptake/degradation, (2) generation of cysteine alpha-carbamate, a toxic analog of NMDA, (3) generation of toxic oxidized cysteine derivatives, (4) chelation of Zn2+ which blocks the NMDA receptor-ionophore, (5) direct interaction with the NMDA receptor redox site(s), (6) generation of free radicals, and (7) formation of S-nitrosocysteine. In addition to these, we describe another new alternative for cytotoxicity: (8) generation of the neurotoxic catecholamine derivative, 5-S-cysteinyl-3,4-dihydroxyphenylacetate (cysdopac).
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Affiliation(s)
- R Janáky
- Brain Research Center, Medical School, University of Tampere, Finland
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45
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Do KQ, Trabesinger AH, Kirsten-Krüger M, Lauer CJ, Dydak U, Hell D, Holsboer F, Boesiger P, Cuénod M. Schizophrenia: glutathione deficit in cerebrospinal fluid and prefrontal cortex in vivo. Eur J Neurosci 2000; 12:3721-8. [PMID: 11029642 DOI: 10.1046/j.1460-9568.2000.00229.x] [Citation(s) in RCA: 398] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Schizophrenia is a major psychiatric disease, which affects the centre of the personality, with severe problems of perception, cognition as well as affective and social behaviour. In cerebrospinal fluid of drug-free schizophrenic patients, a significant decrease in the level of total glutathione (GSH) by 27% (P<0.05) was observed as compared to controls, in keeping with the reported reduced level of its metabolite gamma-glutamylglutamine. With a new non-invasive proton magnetic resonance spectroscopy methodology, GSH level in medial prefrontal cortex of schizophrenic patients was found to be 52% (P = 0.0012) lower than in controls. GSH plays a fundamental role in protecting cells from damage by reactive oxygen species generated among others by the metabolism of dopamine. A deficit in GSH would lead to degenerative processes in the surrounding of dopaminergic terminals resulting in loss of connectivity. GSH also potentiates the N-methyl-D-aspartate (NMDA) receptor response to glutamate, an effect presumably reduced by a GSH deficit, leading to a situation similar to the application of phencyclidine (PCP). Thus, a GSH hypothesis might integrate many established biological aspects of schizophrenia.
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Affiliation(s)
- K Q Do
- Brain Research Institute, University of Zurich and Centre for Research in Psychiatric Neuroscience, University of Lausanne, Route de Cery, CH-1008 Prilly-Lausanne, Switzerland.
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46
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Hermann A, Varga V, Janáky R, Dohovics R, Saransaari P, Oja SS. Interference of S-nitrosoglutathione with the binding of ligands to ionotropic glutamate receptors in pig cerebral cortical synaptic membranes. Neurochem Res 2000; 25:1119-24. [PMID: 11055750 DOI: 10.1023/a:1007626230278] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The interactions of S-nitrosoglutathione (GSNO) with the ionotropic glutamate receptors were studied on synaptic membranes isolated from the pig cerebral cortex. GSNO displaced the binding of [3H]glutamate, 3-[(R)-2-carboxypiperazin-4-yl] [3H]propyl-1-phosphonate ([3H]CPP), a competitive N-methyl-D-aspartate (NMDA) antagonist, and [3H]kainate, with IC50 values in the low micromolar range. It failed to displace (S)-5-fluoro-[3H]willardiine, a selective agonist of 2-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptors. Reduced and oxidized glutathione were almost as effective as GSNO in glutamate and CPP binding. Of the three, GSNO was the most potent in kainate binding. They all stimulated [3H]dizocilpine binding in a concentration-dependent manner. This effect was additive to that of glycine and not mimicked by NO donors such as S-nitroso-N-acetylpenicillamine, 5-amino-3-morpholinyl-1,2,3-oxadiazolium chloride (SIN-1) and nitroglycerin. We assume that GSNO may act as an endogenous ligand at the NMDA and non-NMDA classes of glutamate receptors. In this manner it may facilitate NO transfer and target its delivery to specific sites in these receptors.
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Affiliation(s)
- A Hermann
- Brain Research Center, Medical School, University of Tampere, Finland
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47
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Xin W, Shen XM, Li H, Dryhurst G. Oxidative metabolites of 5-S-cysteinylnorepinephrine are irreversible inhibitors of mitochondrial complex I and the alpha-ketoglutarate dehydrogenase and pyruvate dehydrogenase complexes: possible implications for neurodegenerative brain disorders. Chem Res Toxicol 2000; 13:749-60. [PMID: 10956063 DOI: 10.1021/tx990170t] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The major initial product of the oxidation of norepinephrine (NE) in the presence of L-cysteine is 5-S-cysteinylnorepinephrine which is then further easily oxidized to the dihydrobenzothiazine (DHBT) 7-(1-hydroxy-2-aminoethyl)-3,4-dihydro-5-hydroxy-2H-1, 4-benzothiazine-3-carboxylic acid (DHBT-NE-1). When incubated with intact rat brain mitochondria, DHBT-NE-1 evokes rapid inhibition of complex I respiration without affecting complex II respiration. DHBT-NE-1 also evokes time- and concentration-dependent irreversible inhibition of NADH-coenzyme Q(1) (CoQ(1)) reductase, the pyruvate dehydrogenase complex (PDHC), and alpha-ketoglutarate dehydrogenase (alpha-KGDH) when incubated with frozen and thawed rat brain mitochondria (mitochondrial membranes). The time dependence of the inhibition of NADH-CoQ(1) reductase, PDHC, and alpha-KGDH by DHBT-NE-1 appears to be related to its oxidation, catalyzed by an unknown component of the inner mitochondrial membrane, to electrophilic intermediates which bind covalently to active site cysteinyl residues of these enzyme complexes. The latter conclusion is based on the ability of glutathione to block inhibition of NADH-CoQ(1) reductase, PDHC, and alpha-KGDH by scavenging electrophilic intermediates, generated by the mitochondrial membrane-catalyzed oxidation of DHBT-NE-1, forming glutathionyl conjugates, several of which have been isolated and spectroscopically identified. The possible implications of these results to the degeneration of neuromelanin-pigmented noradrenergic neurons in the locus ceruleus in Parkinson's disease are discussed.
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Affiliation(s)
- W Xin
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma 73019, USA
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Yeh MW, Kaul M, Zheng J, Nottet HS, Thylin M, Gendelman HE, Lipton SA. Cytokine-stimulated, but not HIV-infected, human monocyte-derived macrophages produce neurotoxic levels of l -cysteine. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 164:4265-70. [PMID: 10754324 DOI: 10.4049/jimmunol.164.8.4265] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Approximately one-quarter of individuals with AIDS develop neuropathological symptoms that are attributable to infection of the brain with HIV. The cognitive manifestations have been termed HIV-associated dementia. The mechanisms underlying HIV-associated neuronal injury are incompletely understood, but various studies have confirmed the release of neurotoxins by macrophages/microglia infected with HIV-1 or stimulated by viral proteins, including the envelope glycoprotein gp120. In the present study, we investigated the possibility that l -cysteine, a neurotoxin acting at the N-methyl-d -aspartate subtype of glutamate receptor, could contribute to HIV-associated neuronal injury. Picomolar concentrations of gp120 were found to stimulate cysteine release from human monocyte-derived macrophages (hMDM) in amounts sufficient to injure cultured rat cerebrocortical neurons. TNF-alpha and IL-1beta, known to be increased in HIV-encephalitic brains, as well as a cellular product of cytokine stimulation, ceramide, were also shown to induce release of cysteine from hMDM in a dose-dependent manner. A TNF-alpha-neutralizing Ab and an IL-1betaR antagonist partially blocked gp120-induced cysteine release, suggesting that these cytokines may mediate the actions of gp120. Interestingly, hMDM infected with HIV-1 produced significantly less cysteine than uninfected cells following stimulation with TNF-alpha. Our findings imply that cysteine may play a role in the pathogenesis of neuronal injury in HIV-associated dementia due to its release from immune-activated macrophages but not virus-infected macrophages. Such uninfected cells comprise the vast majority of mononuclear phagocytes (macrophages and microglia) found in HIV-encephalitic brains.
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Affiliation(s)
- M W Yeh
- Cerebrovascular and Neuroscience Research Institute, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
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Abstract
Quinones represent a class of toxicological intermediates which can create a variety of hazardous effects in vivo, including acute cytotoxicity, immunotoxicity, and carcinogenesis. The mechanisms by which quinones cause these effects can be quite complex. Quinones are Michael acceptors, and cellular damage can occur through alkylation of crucial cellular proteins and/or DNA. Alternatively, quinones are highly redox active molecules which can redox cycle with their semiquinone radicals, leading to formation of reactive oxygen species (ROS), including superoxide, hydrogen peroxide, and ultimately the hydroxyl radical. Production of ROS can cause severe oxidative stress within cells through the formation of oxidized cellular macromolecules, including lipids, proteins, and DNA. Formation of oxidatively damaged bases such as 8-oxodeoxyguanosine has been associated with aging and carcinogenesis. Furthermore, ROS can activate a number of signaling pathways, including protein kinase C and RAS. This review explores the varied cytotoxic effects of quinones using specific examples, including quinones produced from benzene, polycyclic aromatic hydrocarbons, estrogens, and catecholamines. The evidence strongly suggests that the numerous mechanisms of quinone toxicity (i.e., alkylation vs oxidative stress) can be correlated with the known pathology of the parent compound(s).
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Affiliation(s)
- J L Bolton
- Department of Medicinal Chemistry and Pharmacognosy (M/C 781), College of Pharmacy, The University of Illinois at Chicago, 833 South Wood Street, Chicago, Illinois 60612-7231, USA.
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Abstract
We have recently found that intracerebroventricular (i.c.v.) administration of glutathione (GSH) inhibits pentylenetetrazol-induced convulsions in mice, suggesting that GSH has an anticonvulsive action. In the present study, we investigated whether endogenous GSH play a role in regulating seizure susceptibility, using L-buthionine-[S,R]-sulfoximine (BSO), a specific inhibitor of GSH biosynthesis. BSO treatment (3.2 micromol i.c.v. x 2, 48 and 24 h prior to experiments) decreased brain GSH level to 31.5% of control, and potentiated pentylenetetrazol-induced convulsions. Potentiation of convulsions by BSO treatment was recovered by supplying GSH (10 nmol, i.c.v.). These results suggest that endogenous GSH functions as an anticonvulsant.
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Affiliation(s)
- K Abe
- Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, The University of Tokyo, Japan.
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