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Bortoluzzi VT, Ribeiro RT, Pinheiro CV, Castro ET, Tavares TQ, Leipnitz G, Sass JO, Castilho RF, Amaral AU, Wajner M. N-Acetylglutamate and N-acetylmethionine compromise mitochondrial bioenergetics homeostasis and glutamate oxidation in brain of developing rats: Potential implications for the pathogenesis of ACY1 deficiency. Biochem Biophys Res Commun 2023; 684:149123. [PMID: 37871522 DOI: 10.1016/j.bbrc.2023.149123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2023] [Revised: 10/08/2023] [Accepted: 10/16/2023] [Indexed: 10/25/2023]
Abstract
Aminoacylase 1 (ACY1) deficiency is an inherited metabolic disorder biochemically characterized by high urinary concentrations of aliphatic N-acetylated amino acids and associated with a broad clinical spectrum with predominant neurological signs. Considering that the pathogenesis of ACY1 is practically unknown and the brain is highly dependent on energy production, the in vitro effects of N-acetylglutamate (NAG) and N-acetylmethionine (NAM), major metabolites accumulating in ACY1 deficiency, on the enzyme activities of the citric acid cycle (CAC), of the respiratory chain complexes and glutamate dehydrogenase (GDH), as well as on ATP synthesis were evaluated in brain mitochondrial preparations of developing rats. NAG mildly inhibited mitochondrial isocitrate dehydrogenase 2 (IDH2) activity, moderately inhibited the activities of isocitrate dehydrogenase 3 (IDH3) and complex II-III of the respiratory chain and markedly suppressed the activities of complex IV and GDH. Of note, the NAG-induced inhibitory effect on IDH3 was competitive, whereas that on GDH was mixed. On the other hand, NAM moderately inhibited the activity of respiratory complexes II-III and GDH activities and strongly decreased complex IV activity. Furthermore, NAM was unable to modify any of the CAC enzyme activities, indicating a selective effect of NAG toward IDH mitochondrial isoforms. In contrast, the activities of citrate synthase, α-ketoglutarate dehydrogenase, malate dehydrogenase, and of the respiratory chain complexes I and II were not changed by these N-acetylated amino acids. Finally, NAG and NAM strongly decreased mitochondrial ATP synthesis. Taken together, the data indicate that NAG and NAM impair mitochondrial brain energy homeostasis.
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Affiliation(s)
- Vanessa Trindade Bortoluzzi
- PPG Ciências Biológicas: Bioquímica, Departamento de Bioquímica, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
| | - Rafael Teixeira Ribeiro
- PPG Ciências Biológicas: Bioquímica, Departamento de Bioquímica, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
| | - Camila Vieira Pinheiro
- PPG Ciências Biológicas: Bioquímica, Departamento de Bioquímica, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
| | - Ediandra Tissot Castro
- PPG Ciências Biológicas: Bioquímica, Departamento de Bioquímica, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
| | - Tailine Quevedo Tavares
- PPG Ciências Biológicas: Bioquímica, Departamento de Bioquímica, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
| | - Guilhian Leipnitz
- PPG Ciências Biológicas: Bioquímica, Departamento de Bioquímica, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
| | - Jörn Oliver Sass
- Research Group Inborn Errors of Metabolism, Department of Natural Sciences & Institute for Functional Gene Analytics, Bonn-Rhein-Sieg University of Applied Sciences, Rheinbach, Germany.
| | - Roger Frigério Castilho
- Departamento de Patologia, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, Campinas, Brazil.
| | - Alexandre Umpierrez Amaral
- PPG Ciências Biológicas: Bioquímica, Departamento de Bioquímica, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil; PPG Atenção Integral à Saúde, Universidade Regional Integrada do Alto Uruguai e das Missões, Erechim, Brazil.
| | - Moacir Wajner
- PPG Ciências Biológicas: Bioquímica, Departamento de Bioquímica, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil; Serviço de Genética Médica, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil.
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2
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Rimmele TS, Li S, Andersen JV, Westi EW, Rotenberg A, Wang J, Aldana BI, Selkoe DJ, Aoki CJ, Dulla CG, Rosenberg PA. Neuronal Loss of the Glutamate Transporter GLT-1 Promotes Excitotoxic Injury in the Hippocampus. Front Cell Neurosci 2022; 15:788262. [PMID: 35035352 PMCID: PMC8752461 DOI: 10.3389/fncel.2021.788262] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 12/08/2021] [Indexed: 12/26/2022] Open
Abstract
GLT-1, the major glutamate transporter in the mammalian central nervous system, is expressed in presynaptic terminals that use glutamate as a neurotransmitter, in addition to astrocytes. It is widely assumed that glutamate homeostasis is regulated primarily by glutamate transporters expressed in astrocytes, leaving the function of GLT-1 in neurons relatively unexplored. We generated conditional GLT-1 knockout (KO) mouse lines to understand the cell-specific functions of GLT-1. We found that stimulus-evoked field extracellular postsynaptic potentials (fEPSPs) recorded in the CA1 region of the hippocampus were normal in the astrocytic GLT-1 KO but were reduced and often absent in the neuronal GLT-1 KO at 40 weeks. The failure of fEPSP generation in the neuronal GLT-1 KO was also observed in slices from 20 weeks old mice but not consistently from 10 weeks old mice. Using an extracellular FRET-based glutamate sensor, we found no difference in stimulus-evoked glutamate accumulation in the neuronal GLT-1 KO, suggesting a postsynaptic cause of the transmission failure. We hypothesized that excitotoxicity underlies the failure of functional recovery of slices from the neuronal GLT-1 KO. Consistent with this hypothesis, the non-competitive NMDA receptor antagonist MK801, when present in the ACSF during the recovery period following cutting of slices, promoted full restoration of fEPSP generation. The inclusion of an enzymatic glutamate scavenging system in the ACSF conferred partial protection. Excitotoxicity might be due to excess release or accumulation of excitatory amino acids, or to metabolic perturbation resulting in increased vulnerability to NMDA receptor activation. Previous studies have demonstrated a defect in the utilization of glutamate by synaptic mitochondria and aspartate production in the synGLT-1 KO in vivo, and we found evidence for similar metabolic perturbations in the slice preparation. In addition, mitochondrial cristae density was higher in synaptic mitochondria in the CA1 region in 20–25 weeks old synGLT-1 KO mice in the CA1 region, suggesting compensation for loss of axon terminal GLT-1 by increased mitochondrial efficiency. These data suggest that GLT-1 expressed in presynaptic terminals serves an important role in the regulation of vulnerability to excitotoxicity, and this regulation may be related to the metabolic role of GLT-1 expressed in glutamatergic axon terminals.
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Affiliation(s)
- Theresa S Rimmele
- Department of Neurology and the F. M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, United States
| | - Shaomin Li
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, United States
| | - Jens Velde Andersen
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Emil W Westi
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Alexander Rotenberg
- Department of Neurology and the F. M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, United States.,Program in Neuroscience, Harvard Medical School, Boston, MA, United States
| | - Jianlin Wang
- Department of Neurology and the F. M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, United States
| | - Blanca Irene Aldana
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Dennis J Selkoe
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, United States
| | - Chiye J Aoki
- Center for Neural Science, New York University, NY, United States.,Neuroscience Institute NYU Langone Medical Center, NY, United States
| | - Chris G Dulla
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, United States
| | - Paul Allen Rosenberg
- Department of Neurology and the F. M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, United States.,Program in Neuroscience, Harvard Medical School, Boston, MA, United States
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3
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Ishimaru Y, Sumino A, Shibagaki F, Yamamuro A, Yoshioka Y, Maeda S. Endogenous Apelin Is Protective Against Age-Associated Loss of Retinal Ganglion Cells in Mice. Front Aging Neurosci 2020; 12:58. [PMID: 32296325 PMCID: PMC7141441 DOI: 10.3389/fnagi.2020.00058] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Accepted: 02/19/2020] [Indexed: 11/24/2022] Open
Abstract
Age-associated loss of retinal ganglion cells (RGCs) causes visual deficits, but there is not yet any therapeutic agent to prevent the loss of these cells. Herein, we report that apelin, an endogenous peptide ligand of APJ receptor, is protective against the age-related loss of RGCs in mice. The mRNA expression of apelin was reduced in the retina of old mice compared with that in young mice, whereas retinal APJ expression increased with age. Immunofluorescence staining showed that APJ was present in RGCs and their surrounding cells expressed apelin. In addition, both functional and histological analyses demonstrated that apelin deficiency accelerated the loss of RGCs associated with age in mice. These results suggest that endogenous apelin plays a protective role against the degeneration of RGCs and that the apelinergic axis may be a new target for preventing age-related visual impairment.
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Affiliation(s)
- Yuki Ishimaru
- Laboratory of Pharmacotherapeutics, Faculty of Pharmaceutical Sciences, Setsunan University, Hirakata, Japan
| | - Akihide Sumino
- Laboratory of Pharmacotherapeutics, Faculty of Pharmaceutical Sciences, Setsunan University, Hirakata, Japan.,Laboratory of Food Chemistry, Yokohama University of Pharmacy, Yokohama, Japan
| | - Fumiya Shibagaki
- Laboratory of Pharmacotherapeutics, Faculty of Pharmaceutical Sciences, Setsunan University, Hirakata, Japan
| | - Akiko Yamamuro
- Laboratory of Pharmacotherapeutics, Faculty of Pharmaceutical Sciences, Setsunan University, Hirakata, Japan
| | - Yasuhiro Yoshioka
- Laboratory of Pharmacotherapeutics, Faculty of Pharmaceutical Sciences, Setsunan University, Hirakata, Japan
| | - Sadaaki Maeda
- Laboratory of Pharmacotherapeutics, Faculty of Pharmaceutical Sciences, Setsunan University, Hirakata, Japan
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The role of memantine in the treatment of major depressive disorder: Clinical efficacy and mechanisms of action. Eur J Pharmacol 2018; 827:103-111. [PMID: 29551658 DOI: 10.1016/j.ejphar.2018.03.023] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 03/12/2018] [Accepted: 03/14/2018] [Indexed: 12/22/2022]
Abstract
A developing body of evidence indicates that disturbed glutamate neurotransmission especially through N-methyl-d-aspartate (NMDA) is central to the pathophysiology of major depressive disorder (MDD) and NMDA receptor antagonists have shown therapeutic potential in the MDD treatment. Memantine is an uncompetitive NMDA receptor antagonist, approved for treatment of Alzheimer's disease (AD) that in contrast to other NMDA receptor antagonists at therapeutic doses does not induce highly undesirable side effects. Neuroprotective properties and well tolerability of memantine have been attributed to its unique pharmacological features such as moderate affinity, rapid blocking kinetics and strongly voltage-dependency. In this review we summarized clinical trial evidence of antidepressant effectiveness of memantine and its mechanisms of action. Available data indicate contradictory findings relating to clinical efficacy suggesting further research is necessary in determining as to whether memantine will eventually be an advantageous therapy for MDD. Preclinical data proposed various neurobiological mechanisms underlying antidepressant-like properties of memantine that are responsible for synaptic plasticity and cell survival.
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5
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Abstract
ALS is a relentless neurodegenerative disease in which motor neurons are the susceptible neuronal population. Their death results in progressive paresis of voluntary and respiratory muscles. The unprecedented rate of discoveries over the last two decades have broadened our knowledge of genetic causes and helped delineate molecular pathways. Here we critically review ALS epidemiology, genetics, pathogenic mechanisms, available animal models, and iPS cell technologies with a focus on their translational therapeutic potential. Despite limited clinical success in treatments to date, the new discoveries detailed here offer new models for uncovering disease mechanisms as well as novel strategies for intervention.
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6
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Thorn TL, He Y, Jackman NA, Lobner D, Hewett JA, Hewett SJ. A Cytotoxic, Co-operative Interaction Between Energy Deprivation and Glutamate Release From System xc- Mediates Aglycemic Neuronal Cell Death. ASN Neuro 2015; 7:1759091415614301. [PMID: 26553727 PMCID: PMC4641554 DOI: 10.1177/1759091415614301] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The astrocyte cystine/glutamate antiporter (system xc(-)) contributes substantially to the excitotoxic neuronal cell death facilitated by glucose deprivation. The purpose of this study was to determine the mechanism by which this occurred. Using pure astrocyte cultures, as well as, mixed cortical cell cultures containing both neurons and astrocytes, we found that neither an enhancement in system xc(-) expression nor activity underlies the excitotoxic effects of aglycemia. In addition, using three separate bioassays, we demonstrate no change in the ability of glucose-deprived astrocytes--either cultured alone or with neurons--to remove glutamate from the extracellular space. Instead, we demonstrate that glucose-deprived cultures are 2 to 3 times more sensitive to the killing effects of glutamate or N-methyl-D-aspartate when compared with their glucose-containing controls. Hence, our results are consistent with the weak excitotoxic hypothesis such that a bioenergetic deficiency, which is measureable in our mixed but not astrocyte cultures, allows normally innocuous concentrations of glutamate to become excitotoxic. Adding to the burgeoning literature detailing the contribution of astrocytes to neuronal injury, we conclude that under our experimental paradigm, a cytotoxic, co-operative interaction between energy deprivation and glutamate release from astrocyte system xc(-) mediates aglycemic neuronal cell death.
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Affiliation(s)
- Trista L Thorn
- Department of Biology, Program in Neuroscience, Syracuse University, NY, USA Department of Neuroscience and Physiology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Yan He
- Department of Biology, Program in Neuroscience, Syracuse University, NY, USA
| | - Nicole A Jackman
- Department of Neuroscience, University of Connecticut Health Center, Farmington, CT, USA
| | - Doug Lobner
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI, USA
| | - James A Hewett
- Department of Biology, Program in Neuroscience, Syracuse University, NY, USA Department of Neuroscience and Physiology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Sandra J Hewett
- Department of Biology, Program in Neuroscience, Syracuse University, NY, USA Department of Neuroscience and Physiology, SUNY Upstate Medical University, Syracuse, NY, USA
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7
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Bhandary S, Aguan K. Pyruvate dehydrogenase complex deficiency and its relationship with epilepsy frequency--An overview. Epilepsy Res 2015; 116:40-52. [PMID: 26354166 DOI: 10.1016/j.eplepsyres.2015.07.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 06/29/2015] [Accepted: 07/05/2015] [Indexed: 12/18/2022]
Abstract
The pyruvate dehydrogenase complex (PDHc) is a member of a family of multienzyme complexes that provides the link between glycolysis and the tricarboxylic acid (TCA) cycle by catalyzing the physiologically irreversible decarboxylation of various 2-oxoacid substrates to their corresponding acyl-CoA derivatives, NADH and CO2. PDHc deficiency is a metabolic disorder commonly associated with lactic acidosis, progressive neurological and neuromuscular degeneration that vary with age and gender. In this review, we aim to discuss the relationship between occurrence of epilepsy and PDHc deficiency associated with the pyruvate dehydrogenase complex (E1α subunit (PDHA1) and E1β subunit (PDHB)) and PDH phosphatase (PDP) deficiency. PDHc plays a crucial role in the aerobic carbohydrate metabolism and regulates the use of carbohydrate as the source of oxidative energy. In severe PDHc deficiency, the energy deficit impairs brain development in utero resulting in physiological and structural changes in the brain that contributes to the subsequent onset of epileptogenesis. Epileptogenesis in PDHc deficiency is linked to energy failure and abnormal neurotransmitter metabolism that progressively alters neuronal excitability. This metabolic blockage might be restricted via inclusion of ketogenic diet that is broken up by β-oxidation and directly converting it to acetyl-CoA, and thereby improving the patient's health condition. Genetic counseling is essential as PDHA1 deficiency is X-linked. The demonstration of the X-chromosome localization of PDHA1 resolved a number of questions concerning the variable phenotype displayed by patients with E1 deficiency. Most patients show a broad range of neurological abnormalities, with the severity showing some dependence on the nature of the mutation in the Elα gene, while PDHB and PDH phosphatase (PDP) deficiencies are of autosomal recessive inheritance. However, in females, the disorder is further complicated by the pattern of X-chromosome inactivation, i.e., unfavorable lyonization. Furthermore research should focus on epileptogenic animal models; this might pave a new way toward identification of the pathophysiology of this challenging disorder.
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Affiliation(s)
- Suman Bhandary
- Department of Biotechnology & Bioinformatics, North-Eastern Hill University, Shillong 793 022, India; Division of Molecular Medicine, Bose Institute, Kolkata 700 054, India
| | - Kripamoy Aguan
- Department of Biotechnology & Bioinformatics, North-Eastern Hill University, Shillong 793 022, India.
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8
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Nicholls DG, Brand MD, Gerencser AA. Mitochondrial bioenergetics and neuronal survival modelled in primary neuronal culture and isolated nerve terminals. J Bioenerg Biomembr 2014; 47:63-74. [DOI: 10.1007/s10863-014-9573-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 08/20/2014] [Indexed: 12/20/2022]
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9
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Duarte J, Schuck PF, Wenk GL, Ferreira GC. Metabolic disturbances in diseases with neurological involvement. Aging Dis 2014; 5:238-55. [PMID: 25110608 DOI: 10.14336/ad.2014.0500238] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Revised: 11/26/2013] [Accepted: 11/27/2013] [Indexed: 12/19/2022] Open
Abstract
Degeneration of specific neuronal populations and progressive nervous system dysfunction characterize neurodegenerative diseases, including Alzheimer's disease and Parkinson's disease. These findings are also reported in inherited diseases such as phenylketonuria and glutaric aciduria type I. The involvement of mitochondrial dysfunction in these diseases was reported, elicited by genetic alterations, exogenous toxins or buildup of toxic metabolites. In this review we shall discuss some metabolic alterations related to the pathophysiology of diseases with neurological involvement and aging process. These findings may help identifying early disease biomarkers and lead to more effective therapies to improve the quality of life of the patients affected by these devastating illnesses.
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Affiliation(s)
| | - Patrícia F Schuck
- Laboratory of inborn errors of metabolism, Universidade do Extremo Sul Catarinense, Brazil
| | - Gary L Wenk
- Department of Psychology, The Ohio State University, Columbus, OH 43210, USA
| | - Gustavo C Ferreira
- Laboratory of inborn errors of metabolism, Universidade do Extremo Sul Catarinense, Brazil
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10
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Ishikawa M. Abnormalities in glutamate metabolism and excitotoxicity in the retinal diseases. SCIENTIFICA 2013; 2013:528940. [PMID: 24386591 PMCID: PMC3872404 DOI: 10.1155/2013/528940] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Accepted: 11/17/2013] [Indexed: 05/14/2023]
Abstract
In the physiological condition, glutamate acts as an excitatory neurotransmitter in the retina. However, excessive glutamate can be toxic to retinal neurons by overstimulation of the glutamate receptors. Glutamate excess is primarily attributed to perturbation in the homeostasis of the glutamate metabolism. Major pathway of glutamate metabolism consists of glutamate uptake by glutamate transporters followed by enzymatic conversion of glutamate to nontoxic glutamine by glutamine synthetase. Glutamate metabolism requires energy supply, and the energy loss inhibits the functions of both glutamate transporters and glutamine synthetase. In this review, we describe the present knowledge concerning the retinal glutamate metabolism under the physiological and pathological conditions.
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Affiliation(s)
- Makoto Ishikawa
- Department of Ophthalmology, Akita Graduate University Faculty of Medicine, 1-1-1 Hondo, Akita 010-8543, Japan
- *Makoto Ishikawa:
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11
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Jafari P, Braissant O, Bonafé L, Ballhausen D. The unsolved puzzle of neuropathogenesis in glutaric aciduria type I. Mol Genet Metab 2011; 104:425-37. [PMID: 21944461 DOI: 10.1016/j.ymgme.2011.08.027] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Revised: 08/23/2011] [Accepted: 08/23/2011] [Indexed: 12/22/2022]
Abstract
Glutaric aciduria type I (GA-I) is a cerebral organic aciduria caused by deficiency of glutaryl-Co-A dehydrogenase (GCDH). GCDH deficiency leads to accumulation of glutaric acid (GA) and 3-hydroxyglutaric acid (3-OHGA), two metabolites that are believed to be neurotoxic, in brain and body fluids. The disorder usually becomes clinically manifest during a catabolic state (e.g. intercurrent illness) with an acute encephalopathic crisis that results in striatal necrosis and in a permanent dystonic-dyskinetic movement disorder. The results of numerous in vitro and in vivo studies have pointed to three main mechanisms involved in the metabolite-mediated neuronal damage: excitotoxicity, impairment of energy metabolism and oxidative stress. There is evidence that during a metabolic crisis GA and its metabolites are produced endogenously in the CNS and accumulate because of limiting transport mechanisms across the blood-brain barrier. Despite extensive experimental work, the relative contribution of the proposed pathogenic mechanisms remains unclear and specific therapeutic approaches have yet to be developed. Here, we review the experimental evidence and try to delineate possible pathogenetic models and approaches for future studies.
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Affiliation(s)
- Paris Jafari
- Inborn Errors of Metabolism, Molecular Pediatrics, Centre Hospitalier Universitaire Vaudois and University of Lausanne, 1011 Lausanne, Switzerland
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12
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Markedly reduced axonal potassium channel expression in human sporadic amyotrophic lateral sclerosis: an immunohistochemical study. Exp Neurol 2011; 232:149-53. [PMID: 21906595 DOI: 10.1016/j.expneurol.2011.08.015] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2011] [Revised: 07/27/2011] [Accepted: 08/18/2011] [Indexed: 12/12/2022]
Abstract
Fasciculations are characteristic features of amyotrophic lateral sclerosis (ALS), suggesting abnormally increased excitability of motor axons. Previous nerve excitability studies have shown reduced axonal potassium currents in ALS patients that may contribute to the hyperexcitability and thereby generation of fasciculations. To clarify changes in axonal ion channel expression in motor axons of ALS, we performed immunohistochemistry of potassium and sodium channels in the C7 and L5 ventral/dorsal roots obtained from five autopsy cases of sporadic ALS. Compared to controls, the immunoreactivity of potassium channels (Kv1.2) was markedly reduced in the ventral roots, but normal in the dorsal roots of all the ALS patients. Nodal sodium channel expression was not significantly different in ALS patients and control subjects. Our results show prominently reduced expression of axonal potassium channels, and provide the neuropathological and biological basis for decreased accommodative potassium currents in motor axons of ALS patients. The axonal hyperexcitability would lead to generation of fasciculations, and possibly enhances motor neuron death in ALS.
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13
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Cechetti F, Worm PV, Pereira LO, Siqueira IR, A Netto C. The modified 2VO ischemia protocol causes cognitive impairment similar to that induced by the standard method, but with a better survival rate. Braz J Med Biol Res 2010; 43:1178-83. [PMID: 21085899 DOI: 10.1590/s0100-879x2010007500124] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2010] [Accepted: 10/29/2010] [Indexed: 11/21/2022] Open
Abstract
Permanent bilateral occlusion of the common carotid arteries (2VO) in the rat has been established as a valid experimental model to investigate the effects of chronic cerebral hypoperfusion on cognitive function and neurodegenerative processes. Our aim was to compare the cognitive and morphological outcomes following the standard 2VO procedure, in which there is concomitant artery ligation, with those of a modified protocol, with a 1-week interval between artery occlusions to avoid an abrupt reduction of cerebral blood flow, as assessed by animal performance in the water maze and damage extension to the hippocampus and striatum. Male Wistar rats (N = 47) aged 3 months were subjected to chronic hypoperfusion by permanent bilateral ligation of the common carotid arteries using either the standard or the modified protocol, with the right carotid being the first to be occluded. Three months after the surgical procedure, rat performance in the water maze was assessed to investigate long-term effects on spatial learning and memory and their brains were processed in order to estimate hippocampal volume and striatal area. Both groups of hypoperfused rats showed deficits in reference (F(₈,₁₇₂) = 7.0951, P < 0.00001) and working spatial memory [2nd (F(₂,₄₄) = 7.6884, P < 0.001), 3rd (F(₂,₄₄) = 21.481, P < 0.00001) and 4th trials (F(₂,₄₄) = 28.620, P < 0.0001)]; however, no evidence of tissue atrophy was found in the brain structures studied. Despite similar behavioral and morphological outcomes, the rats submitted to the modified protocol showed a significant increase in survival rate, during the 3 months of the experiment (P < 0.02).
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Affiliation(s)
- F Cechetti
- Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brasil.
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14
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ElBasiouny SM, Schuster JE, Heckman CJ. Persistent inward currents in spinal motoneurons: important for normal function but potentially harmful after spinal cord injury and in amyotrophic lateral sclerosis. Clin Neurophysiol 2010; 121:1669-79. [PMID: 20462789 PMCID: PMC3000632 DOI: 10.1016/j.clinph.2009.12.041] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2009] [Revised: 11/28/2009] [Accepted: 12/14/2009] [Indexed: 10/19/2022]
Abstract
Meaningful body movements depend on the interplay between synaptic inputs to motoneurons and their intrinsic properties. Injury and disease often alter either or both of these factors and cause motoneuron and movement dysfunction. The ability of the motoneuronal membrane to generate persistent inward currents (PICs) is especially potent in setting the intrinsic excitability of motoneurons and can drastically change the motoneuron output to a given input. In this article, we review the role of PICs in modulating the excitability of spinal motoneurons during health, and their contribution to motoneuron excitability after spinal cord injury (SCI) and in amyotrophic lateral sclerosis (ALS) leading to exaggerated long-lasting reflexes and muscle spasms, and contributing to neuronal degeneration, respectively.
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Affiliation(s)
- S M ElBasiouny
- Physiology, Physical Medicine and Rehabilitation, Physical Therapy and Human Movement Sciences, Northwestern University, Feinberg School of Medicine, Chicago, IL, United States
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15
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Túnez I, Tasset I, Pérez-De La Cruz V, Santamaría A. 3-Nitropropionic acid as a tool to study the mechanisms involved in Huntington's disease: past, present and future. Molecules 2010; 15:878-916. [PMID: 20335954 PMCID: PMC6263191 DOI: 10.3390/molecules15020878] [Citation(s) in RCA: 143] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2009] [Revised: 01/12/2010] [Accepted: 02/01/2010] [Indexed: 11/17/2022] Open
Abstract
Huntington's disease (HD) is an inheritable autosomal-dominant disorder whose causal mechanisms remain unknown. Experimental models have begun to uncover these pathways, thus helping to understand the mechanisms implicated and allowing for the characterization of potential targets for new therapeutic strategies. 3-Nitropropionic acid is known to produce in animals behavioural, biochemical and morphologic changes similar to those occurring in HD. For this reason, this phenotypic model is gaining attention as a valuable tool to mimick this disorder and further developing new therapies. In this review, we will focus on the past and present research of this molecule, to finally bring a perspective on what will be next in this promising field of study.
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Affiliation(s)
- Isaac Túnez
- Departamento de Bioquímica y Biología Molecular, Facultad de Medicina, Instituto Maimónides de Investigaciones Biomédicas de Córdoba, Universidad de Córdoba, Av. Menéndez Pidal s/n, 14004 Córdoba, Spain.
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Sands DC, Morris CE, Dratz EA, Pilgeram A. Elevating optimal human nutrition to a central goal of plant breeding and production of plant-based foods. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2009; 177:377-89. [PMID: 20467463 PMCID: PMC2866137 DOI: 10.1016/j.plantsci.2009.07.011] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
High-yielding cereals and other staples have produced adequate calories to ward off starvation for much of the world over several decades. However, deficiencies in certain amino acids, minerals, vitamins and fatty acids in staple crops, and animal diets derived from them, have aggravated the problem of malnutrition and the increasing incidence of certain chronic diseases in nominally well-nourished people (the so-called diseases of civilization). Enhanced global nutrition has great potential to reduce acute and chronic disease, the need for health care, the cost of health care, and to increase educational attainment, economic productivity and the quality of life. However, nutrition is currently not an important driver of most plant breeding efforts, and there are only a few well-known efforts to breed crops that are adapted to the needs of optimal human nutrition. Technological tools are available to greatly enhance the nutritional value of our staple crops. However, enhanced nutrition in major crops might only be achieved if nutritional traits are introduced in tandem with important agronomic yield drivers, such as resistance to emerging pests or diseases, to drought and salinity, to herbicides, parasitic plants, frost or heat. In this way we might circumvent a natural tendency for high yield and low production cost to effectively select against the best human nutrition. Here we discuss the need and means for agriculture, food processing, food transport, sociology, nutrition and medicine to be integrated into new approaches to food production with optimal human nutrition as a principle goal.
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Affiliation(s)
- David C Sands
- Plant Sciences and Plant Pathology Department, Montana State University, Bozeman, MT, USA.
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Chinopoulos C, Adam-Vizi V. Mitochondria as ATP consumers in cellular pathology. Biochim Biophys Acta Mol Basis Dis 2009; 1802:221-7. [PMID: 19715757 DOI: 10.1016/j.bbadis.2009.08.008] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2009] [Revised: 07/17/2009] [Accepted: 08/17/2009] [Indexed: 12/21/2022]
Abstract
ATP provided by oxidative phosphorylation supports highly complex and energetically expensive cellular processes. Yet, in several pathological settings, mitochondria could revert to ATP consumption, aggravating an existing cellular pathology. Here we review (i) the pathological conditions leading to ATP hydrolysis by the reverse operation of the mitochondrial F(o)F(1)-ATPase, (ii) molecular and thermodynamic factors influencing the directionality of the F(o)F(1)-ATPase, (iii) the role of the adenine nucleotide translocase as the intermediary adenine nucleotide flux pathway between the cytosol and the mitochondrial matrix when mitochondria become ATP consumers, (iv) the role of the permeability transition pore in bypassing the ANT, thereby allowing the flux of ATP directly to the hydrolyzing F(o)F(1)-ATPase, (v) the impact of the permeability transition pore on glycolytic ATP production, and (vi) endogenous and exogenous interventions for limiting ATP hydrolysis by the mitochondrial F(o)F(1)-ATPase.
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Affiliation(s)
- Christos Chinopoulos
- Department of Medical Biochemistry, Semmelweis University, Neurobiochemical Group, Hungarian Academy of Sciences, Budapest, Hungary
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Kong GYX, Van Bergen NJ, Trounce IA, Crowston JG. Mitochondrial dysfunction and glaucoma. J Glaucoma 2009; 18:93-100. [PMID: 19225343 DOI: 10.1097/ijg.0b013e318181284f] [Citation(s) in RCA: 170] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Glaucoma is increasingly recognized as a neurodegenerative disorder, characterized by the accelerated loss of retinal ganglion cells (RGCs) and their axons. Open angle glaucoma prevalence and incidence increase exponentially with increasing age, yet the pathophysiology underlying increasing age as a risk factor for glaucoma is not well understood. Accumulating evidence points to age-related mitochondrial dysfunction playing a key role in the etiology of other neurodegenerative disorders including amyotrophic lateral sclerosis, Alzheimer and Parkinson disease. The 2 major functions of mitochondria are the generation of ATP through oxidative phosphorylation and the regulation of cell death by apoptosis. This review details evidence to support our hypothesis that age-associated mitochondrial dysfunction renders RGCs susceptible to glaucomatous injury by reducing the energy available for repair processes and predisposing RGCs to apoptosis. Eliciting the role of mitochondria in glaucoma pathogenesis may uncover novel therapeutic targets for protecting the optic nerve and preventing vision loss in glaucoma.
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Affiliation(s)
- George Y X Kong
- Centre for Eye Research Australia, University of Melbourne and Royal Victorian Eye and Ear Hospital, Australia
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Bhat MA, Charoo BA, Bhat JI, Ahmad SM, Ali SW, Mufti MUH. Magnesium sulfate in severe perinatal asphyxia: a randomized, placebo-controlled trial. Pediatrics 2009; 123:e764-9. [PMID: 19349375 DOI: 10.1542/peds.2007-3642] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
OBJECTIVE The goal was to study whether postnatal magnesium sulfate infusion could improve neurologic outcomes at discharge for term neonates with severe perinatal asphyxia. METHODS Forty term (> or =37 weeks of gestation) neonates with severe perinatal asphyxia were studied in a prospective, longitudinal, placebo-controlled trial. Patients were assigned randomly to receive either 3 doses of magnesium sulfate infusion at 250 mg/kg per dose (1 mL/kg per dose) 24 hours apart (treatment group) or 3 doses of normal saline infusion (1 mL/kg per dose) 24 hours apart (placebo group). Both groups also received supportive care according to the unit protocol for perinatal asphyxia. RESULTS In the treatment group, moderate encephalopathy was present in 35% (7 of 20) of the patients and severe encephalopathy in 65% (13 of 20) of patients at admission. In the placebo group, 40% (8 of 20) of patients had moderate encephalopathy and 60% (12 of 20) of patients had severe encephalopathy. The mean serum magnesium concentration in the treatment group remained at > or =1.2 mmol/L for 72 hours after the first infusion. At discharge, 22% (4 of 18) of infants in the treatment group had neurologic abnormalities, compared with 56% (10 of 18) of infants in the placebo group. Also, neuroimaging (head computed tomography) performed on day 14 yielded abnormal findings for fewer infants in the treatment group than in the placebo group (16% vs 44%). Infants in the treatment group were more likely to be receiving oral feedings (sucking) at discharge than were those in the placebo group (77% vs 37%). Good short-term outcomes at discharge occurred for 77% of the patients in the treatment group, compared with 37% of the patients in the placebo group. CONCLUSION Postnatal magnesium sulfate treatment improves neurologic outcomes at discharge for term neonates with severe perinatal asphyxia.
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Sørensen IF, Purup S, Ehrich M. Modulation of neurotoxicant-induced increases in intracellular calcium by phytoestrogens differ for amyloid beta peptide (Aβ) and 1-methyl-4-phenyl-pyridine (MPP+). J Appl Toxicol 2009; 29:84-9. [DOI: 10.1002/jat.1376] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Neuroprotective effects of memantine in a mouse model of retinal degeneration induced by rotenone. Brain Res 2008; 1215:208-17. [PMID: 18486118 DOI: 10.1016/j.brainres.2008.04.001] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2008] [Revised: 04/02/2008] [Accepted: 04/02/2008] [Indexed: 11/24/2022]
Abstract
This is the first report of the in vivo effectiveness of memantine as a neuroprotective agent against rotenone-induced retinal toxicity. We tested the hypothesis that uncompetitive NMDAR blockade with memantine prevents mitochondrial dysfunction-related neurodegeneration in vivo, using a mouse model of retinal ganglion cell layer (GCL) degeneration induced by rotenone, a mitochondrial complex I inhibitor. Rotenone induced an increase in cell death and oxidative stress in GCL compared to controls, and these changes were prevented by the co-administration of memantine. The neurotoxic effect of rotenone was also reflected as a decrease in total cell density in GCL and GCL+nerve fiber layer thickness. These changes were also prevented by co-administration of memantine in a dose-dependent manner. In addition, memantine induced an increase in long-term retinal energy metabolic capacity. The results suggest that NMDAR activation contributes to cell death induced by mitochondrial dysfunction and that uncompetitive NMDAR blockade may be used as a neuroprotective strategy against mitochondrial dysfunction in neurodegenerative diseases.
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Bakke MJ, Horsberg TE. Effects of algal-produced neurotoxins on metabolic activity in telencephalon, optic tectum and cerebellum of Atlantic salmon (Salmo salar). AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2007; 85:96-103. [PMID: 17870190 DOI: 10.1016/j.aquatox.2007.08.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2007] [Revised: 08/07/2007] [Accepted: 08/08/2007] [Indexed: 05/17/2023]
Abstract
Neurotoxins from algal blooms have been reported to cause mortality in a variety of species, including sea birds, sea mammals and fish. Farmed fish cannot escape harmful algal blooms and their potential toxins, thus they are more vulnerable for exposure than wild stocks. Sublethal doses of the toxins are likely to affect fish behaviour and may impair cognitive abilities. In the present study, changes in the metabolic activity in different parts of the Atlantic salmon (Salmo salar) brain involved in central integration and cognition were investigated after exposure to sublethal doses of three algal-produced neurotoxins; saxitoxin (STX), brevetoxin (BTX) and domoic acid (DA). Fish were randomly selected to four groups for i.p. injection of saline (control) or one of the neurotoxins STX (10 microg STX/kg bw), BTX (68 microg BTX/kg bw) or DA (6 mg DA/kg bw). In addition, 14C-2-deoxyglucose was i.m. injected to measure brain metabolic activity by autoradiography. The three regions investigated were telencephalon (Tel), optic tectum (OT) and cerebellum (Ce). There were no differences in the metabolic activity after STX and BTX exposure compared to the control in these regions. However, a clear increase was observed after DA exposure. When the subregions with the highest metabolic rate were pseudocoloured in the three brain regions, the three toxins caused distinct differences in the respective patterns of metabolic activation. Fish exposed to STX displayed similar patterns as the control fish, whereas fish exposed to BTX and DA showed highest metabolic activity in subregions different from the control group. All three neurotoxins affected subregions that are believed to be involved in cognitive abilities in fish.
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Affiliation(s)
- Marit Jørgensen Bakke
- Department of Pharmacology and Toxicology, Norwegian School of Veterinary Science, PO Box 8146 Dep., N-0033 Oslo, Norway
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Yadava N, Nicholls DG. Spare respiratory capacity rather than oxidative stress regulates glutamate excitotoxicity after partial respiratory inhibition of mitochondrial complex I with rotenone. J Neurosci 2007; 27:7310-7. [PMID: 17611283 PMCID: PMC6794596 DOI: 10.1523/jneurosci.0212-07.2007] [Citation(s) in RCA: 223] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Partial inhibition of mitochondrial respiratory complex I by rotenone reproduces aspects of Parkinson's disease in rodents. The hypothesis that rotenone enhancement of neuronal cell death is attributable to oxidative stress was tested in an acute glutamate excitotoxicity model using primary cultures of rat cerebellar granule neurons. As little as 5 nM rotenone increased mitochondrial superoxide (O2*-) levels and potentiated glutamate-induced cytoplasmic Ca2+ deregulation, the first irreversible stage of necrotic cell death. However, the potent cell-permeant O2*- trap manganese tetrakis (N-ethylpyridinium-2yl) porphyrin failed to prevent the effects of the inhibitor. The bioenergetic consequences of rotenone addition were quantified by monitoring cell respiration. Glutamate activation of NMDA receptors used the full respiratory capacity of the in situ mitochondria, and >80% of the glutamate-stimulated respiration was attributable to increased cellular ATP demand. Rotenone at 20 nM inhibited basal and carbonyl cyanide p-trifluoromethoxyphenylhydrazone-stimulated cell respiration and caused respiratory failure in the presence of glutamate. ATP synthase inhibition by oligomycin was also toxic in the presence of glutamate. We conclude that the cell vulnerability in the rotenone model of partial complex I deficiency under these specific conditions is primarily determined by spare respiratory capacity rather than oxidative stress.
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Nicholls DG, Johnson-Cadwell L, Vesce S, Jekabsons M, Yadava N. Bioenergetics of mitochondria in cultured neurons and their role in glutamate excitotoxicity. J Neurosci Res 2007; 85:3206-12. [PMID: 17455297 DOI: 10.1002/jnr.21290] [Citation(s) in RCA: 132] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The pathologic activation of NMDA receptors by glutamate is a major contributor to neuronal cell death after stroke. Receptor activation causes a massive influx of calcium into the neuron that is accumulated by the mitochondria. The favored hypothesis is that the calcium loaded mitochondria generate reactive oxygen species that damage and ultimately killed the neuron. In this review this hypothesis is critically re-examined with an emphasis on the role played by deficits in ATP generation. Novel techniques are developed to monitor the bioenergetic status of in situ mitochondria in cultured neurons. Applying these techniques to a model of glutamate excitotoxicity suggests that enhanced reactive oxygen species are a consequence rather than a cause of failed cytoplasmic calcium homeostasis (delayed calcium deregulation, [DCD]), but that prior oxidative damage facilitates DCD by damaging mitochondrial ATP generation. This impacts on current hypotheses relating to the neuroprotective effects of mild mitochondrial uncoupling.
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Abstract
Glaucoma represents a group of neurodegenerative diseases characterised by structural damage to the optic nerve and slow, progressive death of retinal ganglion cells (RGCs). Elevated intraocular pressure is traditionally considered to be the most important risk factor for glaucoma, and treatment options for the disease have hitherto been limited to its reduction. However, visual field loss and RGC death continue to occur in patients with well controlled intraocular pressures and, thus, a consensus has recently emerged that additional treatment strategies are needed. One such strategy is pharmacological neuroprotection, which in the context of glaucoma, refers to the situation in which a drug is deployed to interact with neuronal or glial elements within the retina/optic nerve head and thereby facilitate the survival of RGCs. The advent of animal models of chronic glaucoma has enhanced our understanding of many of the pathological processes occurring in glaucoma and, in doing so, described logical targets for pharmacological intervention. Such targets, which have been manipulated with varying degrees of success in relevant animal paradigms include glutamate receptors, autoimmune elements, neurotrophin deprivation, nitric oxide synthesis, oxidative stress products, sodium and calcium channels, heat shock proteins and apoptotic pathways. With exciting data now emerging from many research laboratories, it is obvious that pharmacological neuroprotection for glaucoma without doubt represents an exciting development in the search for a treatment modality for this debilitating disease.
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Affiliation(s)
- Glyn Chidlow
- Ophthalmic Research Laboratories, South Australian Institute of Ophthalmology, Hanson Institute, Adelaide, South Australia, Australia.
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Van Damme P, Dewil M, Robberecht W, Van Den Bosch L. Excitotoxicity and amyotrophic lateral sclerosis. NEURODEGENER DIS 2006; 2:147-59. [PMID: 16909020 DOI: 10.1159/000089620] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Since its description by Charcot more than 130 years ago, the pathogenesis of selective motor neuron degeneration in amyotrophic lateral sclerosis (ALS) remains unsolved. Over the years, many pathogenic mechanisms have been proposed. Amongst others these include: oxidative stress, excitotoxicity, aggregate formation, inflammation, growth factor deficiency and neurofilament disorganization. This multitude of contributing factors indicates that ALS is a complex disease and also suggests that ALS is a multifactorial disorder. Excitotoxicity is not the newest and most spectacular hypothesis in the ALS field, but it is undoubtedly one of the most robust pathogenic mechanisms supported by an impressive amount of evidence. Moreover, the therapeutic efficacy of riluzole, the only drug proven to slow disease progression in ALS, is most likely related to its anti-excitotoxic properties. In this review, we will give an overview of the arguments in favor of the involvement of excitotoxicity in ALS and of the possible mechanisms leading to motor neuron death. We will also summarize the intrinsic properties of motor neurons that render these cells particularly vulnerable to excitotoxicity and could explain the selective vulnerability of motor neurons in ALS. All this information could help to develop new and better therapeutic strategies that could protect motor neurons from excitotoxicity.
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Affiliation(s)
- P Van Damme
- Neurobiology, Campus Gasthuisberg, Leuven, Belgium
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Volbracht C, van Beek J, Zhu C, Blomgren K, Leist M. Neuroprotective properties of memantine in different in vitro and in vivo models of excitotoxicity. Eur J Neurosci 2006; 23:2611-22. [PMID: 16817864 DOI: 10.1111/j.1460-9568.2006.04787.x] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The pathogenesis of stroke, trauma and chronic degenerative diseases, such as Alzheimer's disease (AD), has been linked to excitotoxic processes due to inappropriate stimulation of the N-methyl-D-aspartate receptor (NMDA-R). Attempts to use potent competitive NMDA-R antagonists as neuroprotectants have shown serious side-effects in patients. As an alternative approach, we were interested in the anti-excitotoxic properties of memantine, a well-tolerated low affinity uncompetitive NMDA-R antagonist presently used as an anti-dementia agent. We explored in a series of models of increasing complexity, whether this voltage-dependent channel blocker had neuroprotective properties at clinically relevant concentrations. As expected, memantine protected neurons in organotypic hippocampal slices or dissociated cultures from direct NMDA-induced excitotoxicity. However, low concentrations of memantine were also effective in neuronal (cortical neurons and cerebellar granule cells) stress models dependent on endogenous glutamate stimulation and mitochondrial stress, i.e. exposure to hypoxia, the mitochondrial toxin 1-methyl-4-phenylpyridinium (MPP+) or a nitric oxide (NO) donor. Furthermore, memantine reduced lethality and brain damage in vivo in a model of neonatal hypoxia-ischemia (HI). Finally, we investigated functional rescue (neuronal capacity to migrate along radial glia) by memantine in cerebellar microexplant cultures exposed to the indirect excitotoxin 3-nitropropionic acid (3-NP). Potent NMDA-R antagonists, such as (+)MK-801, are known to block neuronal migration in microexplant cultures. Interestingly, memantine significantly restored the number of neurons able to migrate out of the stressed microexplants. These findings suggest that inhibition of the NMDA-R by memantine is sufficient to block excitotoxicity, while still allowing some degree of signalling.
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Affiliation(s)
- Christiane Volbracht
- Department of Disease Biology, H. Lundbeck A/S, Ottiliavej 9, 2500 Valby, Denmark.
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Van Den Bosch L, Van Damme P, Bogaert E, Robberecht W. The role of excitotoxicity in the pathogenesis of amyotrophic lateral sclerosis. Biochim Biophys Acta Mol Basis Dis 2006; 1762:1068-82. [PMID: 16806844 DOI: 10.1016/j.bbadis.2006.05.002] [Citation(s) in RCA: 340] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2006] [Revised: 05/04/2006] [Accepted: 05/10/2006] [Indexed: 12/14/2022]
Abstract
Unfortunately and despite all efforts, amyotrophic lateral sclerosis (ALS) remains an incurable neurodegenerative disorder characterized by the progressive and selective death of motor neurons. The cause of this process is mostly unknown, but evidence is available that excitotoxicity plays an important role. In this review, we will give an overview of the arguments in favor of the involvement of excitotoxicity in ALS. The most important one is that the only drug proven to slow the disease process in humans, riluzole, has anti-excitotoxic properties. Moreover, consumption of excitotoxins can give rise to selective motor neuron death, indicating that motor neurons are extremely sensitive to excessive stimulation of glutamate receptors. We will summarize the intrinsic properties of motor neurons that could render these cells particularly sensitive to excitotoxicity. Most of these characteristics relate to the way motor neurons handle Ca(2+), as they combine two exceptional characteristics: a low Ca(2+)-buffering capacity and a high number of Ca(2+)-permeable AMPA receptors. These properties most likely are essential to perform their normal function, but under pathological conditions they could become responsible for the selective death of motor neurons. In order to achieve this worst-case scenario, additional factors/mechanisms could be required. In 1 to 2% of the ALS patients, mutations in the SOD1 gene could shift the balance from normal motor neuron excitation to excitotoxicity by decreasing glutamate uptake in the surrounding astrocytes and/or by interfering with mitochondrial function. We will discuss point by point these different pathogenic mechanisms that could give rise to classical and/or slow excitotoxicity leading to selective motor neuron death.
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Affiliation(s)
- L Van Den Bosch
- Neurobiology, Campus Gasthuisberg O&N2, PB1022, Herestraat 49, B-3000 Leuven, Belgium.
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Abstract
Excitotoxicity describes the process of neuronal injury by excess stimulation of amino acid receptors. This form of insult was first described in the retina, and subsequently has been shown to be an important component of the pathogenesis of ischaemic and traumatic injury in the central nervous system. Furthermore, there is increasing evidence that excitotoxicity is involved in several chronic neurological conditions, and anti-excitotoxic treatment has already been approved for some of these conditions. A large-scale trial is currently underway that will determine the efficacy of an anti-excitotoxic drug (memantine) in the management of glaucoma. This review provides an overview of neurotransmission and the mechanisms of excitotoxicity. The evidence for excitotoxicity as a component of certain neurological diseases, including glaucoma, is discussed.
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Affiliation(s)
- Robert J Casson
- Department of Ophthalmology and Visual Science, Royal Adelaide Hospital, North Tce., Adelaide, SA 5000, Australia.
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Volbracht C, Chua BT, Ng CP, Bahr BA, Hong W, Li P. The critical role of calpain versus caspase activation in excitotoxic injury induced by nitric oxide. J Neurochem 2005; 93:1280-92. [PMID: 15934947 DOI: 10.1111/j.1471-4159.2005.03122.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The pathogenesis of various acute and chronic neurodegenerative disorders has been linked to excitotoxic processes and excess generation of nitric oxide. We investigated the deleterious effects of calpain activation in nitric oxide-elicited neuronal apoptosis. In this model, nitric oxide triggers apoptosis of murine cerebellar granule cells by an excitotoxic mechanism requiring glutamate exocytosis and receptor-mediated intracellular calcium overload. Here, we found that calcium-dependent cysteine proteases, calpains, were activated early in apoptosis of cerebellar granule cells exposed to nitric oxide. Release of the proapoptogenic factors cytochrome c and apoptosis-inducing factor from mitochondria preceded neuronal death. However, caspases-3 was not activated. We observed that procaspase-9 was cleaved by calpains to proteolytically inactive fragments. Inhibition of calpains by different synthetic calpain inhibitors or by adenovirally mediated expression of the calpastatin inhibitory domain prevented mitochondrial release of cytochrome c and apoptosis-inducing factor, calpain-specific proteolysis and neuronal apoptosis. We conclude that (i) signal transduction pathways exist that prevent the entry of neurons into a caspase-dependent death after mitochondrial release of cytochrome c and (ii) that calpain activation links nitric oxide-triggered excitotoxic events with the execution of caspase-independent apoptosis in neurons.
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Schauwecker PE. Susceptibility to excitotoxic and metabolic striatal neurodegeneration in the mouse is genotype dependent. Brain Res 2005; 1040:112-20. [PMID: 15804432 DOI: 10.1016/j.brainres.2005.01.067] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2004] [Revised: 01/21/2005] [Accepted: 01/21/2005] [Indexed: 11/21/2022]
Abstract
Previously, we had reported that hippocampal susceptibility to the neurotoxic effects of excitotoxin administration is strain dependent [Schauwecker and Steward, Proc. Natl. Acad. Sci. U.S.A. 94 (1997) 4103]. However, it has been unclear whether strain-related gene products may play a similar role in providing protection against drugs that produce striatal lesions. The present series of experiments sought to elucidate whether genetic background alters neuronal viability within the striatum following metabolic or excitotoxic injury. Thus, we have examined the effect of mouse strain on susceptibility to striatal injury using well-characterized animal models of Huntington's disease by examining whether C57BL/6 mice, previously identified as resistant to excitotoxin-induced hippocampal cell death, are resistant to quinolinate, malonate, and 3-nitropropionic acid (3-NP). Intrastriatal injection of either malonate or quinolinate and systemic administration of 3-NP resulted in significantly smaller striatal lesions in C57BL/6 mice as compared to FVB/N mice, previously identified as susceptible to hippocampal excitotoxic injury. The existence of an animal strain with decreased resistance to striatal lesions suggests that there are mediating factors involved in the preferential vulnerability of the striatum to neurotoxic lesioning. The identification of these factors could provide strategies for therapeutic intervention in Huntington's disease.
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Affiliation(s)
- Paula Elyse Schauwecker
- Department of Cell and Neurobiology, University of Southern California Keck School of Medicine, BMT 401, 1333 San Pablo Street, Los Angeles, CA 90089-9112, USA.
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Zugno AI, Franzon R, Chiarani F, Bavaresco CS, Wannmacher CMD, Wajner M, Wyse ATS. Evaluation of the mechanism underlying the inhibitory effect of guanidinoacetate on brain Na
+
, K
+
‐ATPase activity. Int J Dev Neurosci 2004; 22:191-6. [PMID: 15245754 DOI: 10.1016/j.ijdevneu.2004.05.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2004] [Revised: 05/03/2004] [Accepted: 05/04/2004] [Indexed: 11/15/2022] Open
Abstract
Guanidinoacetate methyltransferase deficiency (GAMT-deficiency) is an inherited neurometabolic disorder clinically characterized by epilepsy and mental retardation and biochemically by accumulation of guanidinoacetate (GAA) and depletion of creatine. Although the neurological symptoms are predominant, the pathogenesis of the brain dysfunction in this disorder is not yet established. In the present study we investigated the in vitro effect of GAA on Na+, K+-ATPase and Mg2+-ATPase activities in synaptic plasma membrane from hippocampus of young rats. Results showed that GAA significantly inhibited Na+, K+-ATPase activity without affecting Mg2+-ATPase activity. We also evaluated the effect of glutathione (GSH), trolox, Nomega-nitro-L-arginine methyl ester (L-NAME) and taurine (Tau) on the inhibition elicited by GAA on Na+, K+-ATPase activity. GSH, trolox, L-NAME and Tau per se did not alter Na+, K+-ATPase activity. However, L-NAME and taurine prevented the inhibitory effect of GAA on this enzyme activity. Our findings suggest that the inhibition of Na+, K+-ATPase activity caused by GAA is possibly mediated by nitric oxide (NO) formation and/or synaptic membrane alteration. The present data may contribute to the understanding of the neurological dysfunction characteristic of GAMT-deficient patients.
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Affiliation(s)
- Alexandra I Zugno
- Departamento de Bioquímica, ICBS, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600-Anexo, CEP 90035-003, Porto Alegre, RS, Brazil
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de Assis DR, Ribeiro CAJ, Rosa RB, Schuck PF, Dalcin KB, Vargas CR, Wannmacher CMD, Dutra-Filho CS, Wyse ATS, Briones P, Wajner M. Evidence that antioxidants prevent the inhibition of Na+,K(+)-ATPase activity induced by octanoic acid in rat cerebral cortex in vitro. Neurochem Res 2003; 28:1255-63. [PMID: 12892042 DOI: 10.1023/a:1024244915832] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The objective of the present study was to investigate the in vitro effects of octanoic acid, which accumulates in medium-chain acyl-CoA dehydrogenase (MCAD) deficiency and in Reye syndrome, on key enzyme activities of energy metabolism in the cerebral cortex of young rats. The activities of the respiratory chain complexes I-IV, creatine kinase, and Na+,K(+)-ATPase were evaluated. Octanoic acid did not alter the electron transport chain and creatine kinase activities, but, in contrast, significantly inhibited Na+,K(+)-ATPase activity both in synaptic plasma membranes and in homogenates prepared from cerebral cortex. Furthermore, decanoic acid, which is also increased in MCAD deficiency, and oleic acid strongly reduced Na+,K(+)-ATPase activity, whereas palmitic acid had no effect. We also examined the effects of incubating glutathione and trolox (alpha-tocopherol) alone or with octanoic acid on Na+,K(+)-ATPase activity. Tested compounds did not affect Na+,K(+)-ATPase activity by itself, but prevented the inhibitory effect of octanoic acid. These results suggest that inhibition of Na+,K(+)-ATPase activity by octanoic acid is possibly mediated by oxidation of essential groups of the enzyme. Considering that Na+,K(+)-ATPase is critical for normal brain function, it is feasible that the significant inhibition of this enzyme activity by octanoate and also by decanoate may be related to the neurological dysfunction found in patients affected by MCAD deficiency and Reye syndrome.
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Affiliation(s)
- Dênis R de Assis
- Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, UFRGS, Porto Alegre, RS, Brazil
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34
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Streck EL, Matté C, Vieira PS, Calcagnotto T, Wannmacher CMD, Wajner M, Wyse ATS. Impairment of energy metabolism in hippocampus of rats subjected to chemically-induced hyperhomocysteinemia. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1637:187-92. [PMID: 12697299 DOI: 10.1016/s0925-4439(03)00019-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Homocystinuria is an inherited metabolic disease biochemically characterized by tissue accumulation of homocysteine (Hcy). Mental retardation, ischemia and other neurological features, whose mechanisms are still obscure are common symptoms in homocystinuric patients. In this work, we investigated the effect of Hcy administration in Wistar rats on some parameters of energy metabolism in the hippocampus, a cerebral structure directly involved with cognition. The parameters utilized were 14CO2 production, glucose uptake, lactate release and the activities of succinate dehydrogenase and cytochrome c oxidase (COX). Chronic hyperhomocysteinemia was induced by subcutaneous administration of Hcy twice a day from the 6th to the 28th day of life in doses previously determined in our laboratory. Control rats received saline in the same volumes. Rats were killed 12 h after the last injection. Results showed that Hcy administration significantly diminished 14CO2 production and glucose uptake, as well as succinate dehydrogenase and COX activities. It is suggested that impairment of brain energy metabolism may be related to the neurological symptoms present in homocystinuric patients.
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Affiliation(s)
- Emilio L Streck
- Departamento de Bioquímica, ICBS, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600-Anexo, CEP 90035-003, Porto Alegre, RS, Brazil
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35
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Abstract
MPTP burst upon the medical landscape two decades ago, first as a mysterious parkinsonian epidemic, triggering an unparalleled quest for the toxin's identity, and closely followed by an intense pursuit of its cellular mechanisms of action. MPTP treatment created an animal model of many features of Parkinson's disease (PD), used primarily in primates and later in mice. The critical role of oxidative stress damage to vulnerable dopamine neurons, as well as for neurodegenerative diseases in general, emerged from MPTP neurotoxicity. A remarkable cross-fertilization of basic and clinical findings, including genetic and epidemiologic studies, has greatly advanced our understanding of PD and revealed multiple factors contributing to the parkinsonian phenotypes. Brain imaging localizes sites of action and provides potential presymptomatic diagnostic testing. Epidemiologic reports linking PD with pesticide exposure were complimented by supportive evidence from biochemical studies of MPTP and structurally related compounds, especially after low-level, long-term exposure. Genetic studies on the role of risk genes, such as alpha-synuclein or parkin, have been validated by biochemical, anatomical and neurochemical investigations showing factors interacting to produce pathophysiology in the animal model. Focusing on the pivotal role of mitochondria, subcellular pathways participating in cell death have been clarified by unraveling similar sites of action of MPTP. Along the way, compounds antagonizing or potentiating MPTP effects indicated new PD therapies, some of the former achieving clinical trials. The future is encouraging for combating PD and will continue to benefit from the MPTP neurotoxicity model.
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Affiliation(s)
- Samuel G Speciale
- Department of Psychiatry, University of Texas Southwestern Medical School, Dallas, TX 75390, USA.
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Streck EL, Zugno AI, Tagliari B, Wannmacher C, Wajner M, Wyse ATS. Inhibition of Na+, K+-ATPase activity by the metabolites accumulating in homocystinuria. Metab Brain Dis 2002; 17:83-91. [PMID: 12083340 DOI: 10.1023/a:1015594111778] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Homocystinuria is an inborn error of sulfur amino acid metabolism characterized predominantly by vascular and nervous system dysfunction. In this study we determined the in vitro effects of homocysteine and methionine, metabolites which accumulate in homocystinuria, on Na+, K+-ATPase, and Mg2+-ATPase activities in synaptic membranes from the hippocampus of rats. The results showed that both metabolites significantly inhibit Na+, K+-ATPase but not Mg2+-ATPase activity at concentrations usually observed in plasma of homocystinuric patients. Furthermore, incubation of hippocampal homogenates with homocysteine also elicited an inhibition of the enzyme activity which was however prevented by the simultaneous addition of cysteine to the medium. In addition, cysteine or methionine per se did not modify the two enzymatic activities. These findings indicate that oxidation of critical groups in the enzyme may possibly be involved in homocysteine inhibitory effect. Moreover, kinetic studies performed to investigate the interaction between homocysteine and methionine on Na+, K+-ATPase inhibition suggested a common site for the two amino acids in the enzyme. Considering the critical role exerted by Na+, K+-ATPase in brain, it is proposed that the inhibition provoked by homocysteine and methionine on the enzyme activity may be possibly related to the brain dysfunction characteristic of homocystinuria.
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Affiliation(s)
- Emilio L Streck
- Departamento de Bioquímica, Instituto de Ciências Básicas de Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
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38
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Kraus MM, Bashkatova V, Vanin A, Philippu A, Prast H. Dizocilpine inhibits amphetamine-induced formation of nitric oxide and amphetamine-induced release of amino acids and acetylcholine in the rat brain. Neurochem Res 2002; 27:229-35. [PMID: 11958521 DOI: 10.1023/a:1014836621717] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Glutamate receptor activation participates in mediation of neurotoxic effects in the striatum induced by the psychomotor stimulant amphetamine. The effects of the non-competitive NMDA receptor antagonist dizocilpine (MK-801) on amphetamine-induced toxicity and formation of nitric oxide (NO) in both striatum and cortex and on induced transmitter release in the nucleus accumbens were investigated. Repeated, systemic application of amphetamine elevated striatal and cortical lipid peroxidation and NO production. Moreover, amphetamine caused an immediate release of acetylcholine and aspartate and a delayed release of GABA in the nucleus accumbens. Surprisingly, glutamate release was not affected. Dizocilpine abolished the amphetamine-induced lipid peroxidation and NO production in striatum and cortex and diminished the elevation of neurotransmitter release. These findings suggest that amphetamine evokes neurotoxic effects in both striatal and cortical brain areas that are prevented by inhibiting NMDA receptor activation. The amphetamine-induced acetylcholine, aspartate and GABA release in the nucleus accumbens is also mediated through NMDA receptor-dependent mechanisms. Interestingly, the enhanced aspartate release might contribute to NMDA receptor activation in the nucleus accumbens, while glutamate does not seem to mediate amphetamine-evoked transmitter release in this striatal brain area.
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Affiliation(s)
- Michaela M Kraus
- Department of Pharmacology and Toxicology, University of Innsbruck, Austria
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39
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da Silva CG, Ribeiro CAJ, Leipnitz G, Dutra-Filho CS, Wyse AT ATS, Wannmacher CMD, Sarkis JJF, Jakobs C, Wajner M. Inhibition of cytochrome c oxidase activity in rat cerebral cortex and human skeletal muscle by D-2-hydroxyglutaric acid in vitro. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1586:81-91. [PMID: 11781152 DOI: 10.1016/s0925-4439(01)00088-6] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
L-2-Hydroxyglutaric (LGA) and D-2-hydroxyglutaric (DGA) acids are the characteristic metabolites accumulating in the neurometabolic disorders known as L-2-hydroxyglutaric aciduria and D-2-hydroxyglutaric aciduria, respectively. Although these disorders are predominantly characterized by severe neurological symptoms, the neurotoxic mechanisms of brain damage are virtually unknown. In this study we have evaluated the role of LGA and DGA at concentrations ranging from 0.01 to 5.0 mM on various parameters of energy metabolism in cerebral cortex slices and homogenates of 30-day-old Wistar rats, namely glucose uptake, CO(2) production and the respiratory chain enzyme activities of complexes I to IV. DGA significantly decreased glucose utilization (2.5 and 5.0 mM) by brain homogenates and CO(2) production (5 mM) by brain homogenates and slices, whereas LGA had no effect on either measurement. Furthermore, DGA significantly inhibited cytochrome c oxidase activity (complex IV) (EC 1.9.3.1) in a dose-dependent manner (35-95%) at doses as low as 0.5 mM, without compromising the other respiratory chain enzyme activities. In contrast, LGA did not interfere with these activities. Our results suggest that the strong inhibition of cytochrome c oxidase activity by increased levels of DGA could be related to the neurodegeneration of patients affected by D-2-hydroxyglutaric aciduria.
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Affiliation(s)
- Cleide G da Silva
- Department of Biochemistry, Institute of Basic Sciences and Health, UFRGS, Porto Alegre, RS, Brazil
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40
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Volbracht C, Fava E, Leist M, Nicotera P. Calpain inhibitors prevent nitric oxide-triggered excitotoxic apoptosis. Neuroreport 2001; 12:3645-8. [PMID: 11726766 DOI: 10.1097/00001756-200112040-00008] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The pathogenesis of some neurodegenerative disorders has been linked to excitotoxicity, excess generation of nitric oxide (NO) and apoptosis. Here, we used a model of NO-triggered neuronal apoptosis that was strictly dependent on autocrine NMDA receptor (NMDA-R) activation and intracellular Ca2+ increase. We investigated the efficiency and potentially beneficial effects of calpain inhibition. Three calpain inhibitors that prevented intracellular fodrin proteolysis also blocked apoptotic features such as decrease in mitochondrial membrane potential, chromatin breakdown, and subsequent death of cerebellar granule neurons exposed to NO donors (S-nitroso-L-glutathione, S-nitroso-N-acetyl-d,l-penicillamine, and diethylamino-diazenolate-2-oxide). Since inhibitors did not interfere with NMDA-R activation, we suggest that block of calpains blunts NO-triggered neuronal apoptosis by stopping the cascade downstream of primary autocrine excitotoxic events.
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Affiliation(s)
- C Volbracht
- Molecular Toxicology, University of Konstanz, Konstanz, Germany
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41
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Silva AR, Silva CG, Ruschel C, Helegda C, Wyse AT, Wannmacher CM, Wajner M, Dutra-Filho CS. L-pyroglutamic acid inhibits energy production and lipid synthesis in cerebral cortex of young rats in vitro. Neurochem Res 2001; 26:1277-83. [PMID: 11885778 DOI: 10.1023/a:1014289232039] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In the present study we investigated the effects of L-pyroglutamic acid (PGA), which predominantly accumulates in the inherited metabolic diseases glutathione synthetase deficiency (GSD) and gamma-glutamylcysteine synthetase deficiency (GCSD), on some in vitro parameters of energy metabolism and lipid biosynthesis. We evaluated the rates of CO2 production and lipid synthesis from [U-14C]acetate, as well as ATP levels and the activities of creatine kinase and of the respiratory chain complexes I-IV in cerebral cortex of young rats in the presence of PGA at final concentrations ranging from 0.5 to 3 mM. PGA significantly reduced brain CO2 production by 50% at the concentrations of 0.5 to 3 mM, lipid biosynthesis by 20% at concentrations of 0.5 to 3 mM and ATP levels by 52% at the concentration of 3 mM. Regarding the enzyme activities, PGA significantly decreased NADH:cytochrome c oxireductase (complex I plus CoQ plus complex III) by 40% at concentrations of 0.5-3.0 mM and cytochrome c oxidase activity by 22-30% at the concentration of 3.0 mM, without affecting the activities of succinate dehydrogenase, succinate:DCPIP oxireductase (complex II), succinate:cytochrome c oxireductase (complex II plus CoQ plus complex III) or creatine kinase. The results strongly indicate that PGA impairs brain energy production. If these effects also occur in humans, it is possible that they may contribute to the neuropathology of patients affected by these diseases.
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Affiliation(s)
- A R Silva
- Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
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42
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Streck EL, Zugno AI, Tagliari B, Franzon R, Wannmacher CM, Wajner M, Wyse AT. Inhibition of rat brain Na+, K+-ATPase activity induced by homocysteine is probably mediated by oxidative stress. Neurochem Res 2001; 26:1195-200. [PMID: 11874200 DOI: 10.1023/a:1013907104585] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The objective of the present study was to investigate the effects of preincubation of hippocampus homogenates in the presence of homocysteine or methionine on Na+, K+-ATPase and Mg2+-ATPase activities in synaptic membranes of rats. Homocysteine significantly inhibited Na+, K+-ATPase activity, whereas methionine had no effect. Mg2+-ATPase activity was not altered by the metabolites. We also evaluated the effect of incubating glutathione, cysteine, dithiothreitol, trolox, superoxide dismutase and GM1 ganglioside alone or incubation with homocysteine on Na+, K+-ATPase activity. Tested compounds did not alter Na+, K+-ATPase and Mg2+-ATPase activities, but except for trolox, prevented the inhibitory effect of homocysteine on Na+, K+-ATPase activity. These results suggest that inhibition of this enzyme activity by homocysteine is possibly mediated by free radicals and may contribute to the neurological dysfunction found in homocystinuric patients.
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Affiliation(s)
- E L Streck
- Departamento de Bioquímica, ICBS, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
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43
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Ischemia-Induced Ionic Mechanisms of Injury in the Developing Brain. Brain Inj 2001. [DOI: 10.1007/978-1-4615-1721-4_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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44
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Yun SW, Gärtner U, Arendt T, Hoyer S. Increase in vulnerability of middle-aged rat brain to lead by cerebral energy depletion. Brain Res Bull 2000; 52:371-8. [PMID: 10922516 DOI: 10.1016/s0361-9230(00)00274-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The neurotoxic effects of low-level lead (Pb) during senescence are increasing interests of importance. We investigated the effects of low-level Pb on the brain in a normal condition and a pathophysiological condition of energy shortage that is commonly found in age-related neurological diseases. Middle-aged rats (15 months old) were exposed to 200 mg/l Pb acetate in drinking water for 2 months and thereafter received bilateral intracerebroventricular injections of streptozotocin (STZ). After 1 month's additional exposure to the same level of Pb solution as before the rats were sacrificed. Blood and brain Pb levels were measured by graphite furnace atomic absorption spectrophotometry. Energy-rich phosphate levels in the brain were determined by high-performance liquid chromatography equipped with a UV detector. Astroglial activation and glucose-regulated protein (GRP)94 expression were examined immunohistochemically. Exposure to Pb increased the blood Pb level to 10.8 microg/dl and the brain Pb level to 0.052 microg/g. But a significant additional increase in the brain Pb level, to 0.101 microg/g, became obvious in rats treated with Pb + STZ. Both Pb and STZ induced perturbation in brain energy metabolism, but no further alteration in energy metabolite levels was found in rats treated with Pb + STZ. Astroglial activation and GRP94-positive astrocytes and neurons were found only in the brains of Pb + STZ-treated rats. These results suggest that exposure to low-level Pb can perturb brain energy metabolism and the brain becomes more vulnerable to Pb when it is under energy stress.
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Affiliation(s)
- S W Yun
- Department of Pathochemistry and General Neurochemistry, University of Heidelberg, Heidelberg, Germany
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45
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Silva CG, Silva AR, Ruschel C, Helegda C, Wyse AT, Wannmacher CM, Dutra-Filho CS, Wajner M. Inhibition of energy production in vitro by glutaric acid in cerebral cortex of young rats. Metab Brain Dis 2000; 15:123-31. [PMID: 11092579 DOI: 10.1007/bf02679979] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
The present study investigated the effects of glutaric acid (GA), which predominantly accumulates in glutaric acidemia type I (GA-I), on some in vitro parameters of energy metabolism in cerebral cortex of rats. We first evaluated CO2 production from [U-14C] acetate, as well as ATP levels in brain of young Wistar rats. The effect of the acid on the activities of the respiratory chain complexes were also investigated. GA was tested at final concentrations ranging from 0.5 to 5.0 mM. GA significantly reduced brain CO2 production by 50% at the concentrations of 0.5 to 3.0 mM, ATP levels by 25% at the concentration of 3.0 mM, succinate:cytochrome C oxireductase (complex II plus CoQ plus complex III) by 25% at 5 mM concentration, and NADH:cytochrome C oxireductase (complex I plus CoQ plus complex Ill) by 25% at 2.5 and 5 mM concentrations. The results strongly indicate that GA impairs brain energy production. If these effects also occur in humans, it is possible that they may contribute to the neuropathology of patients affected by GA-I.
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Affiliation(s)
- C G Silva
- Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brasil
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46
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Deleu D, Hanssens Y. Cerebellar dysfunction in chronic toluene abuse: beneficial response to amantadine hydrochloride. JOURNAL OF TOXICOLOGY. CLINICAL TOXICOLOGY 2000; 38:37-41. [PMID: 10696922 DOI: 10.1081/clt-100100913] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
CASE REPORT A 21-year-old man who had sniffed toluene since the age of 13 presented with a 4-year history of progressive cerebellar dysfunction and visual deterioration. The patient's condition did not improve despite 5 months of abstinence. Magnetic resonance imaging revealed cerebral atrophy and hypointensity signals in the white matter and bilaterally in the globus pallidus, thalamus, red nucleus, and substantia nigra. Amantadine hydrochloride therapy (100 mg/d, then 200 mg/d) resulted in dramatic improvement of his cerebellar and visual symptoms.
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Affiliation(s)
- D Deleu
- Sultan Qaboos University, Al-Khod, Sultanate of Oman.
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47
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Lee WT, Shen YZ, Chang C. Neuroprotective effect of lamotrigine and MK-801 on rat brain lesions induced by 3-nitropropionic acid: evaluation by magnetic resonance imaging and in vivo proton magnetic resonance spectroscopy. Neuroscience 2000; 95:89-95. [PMID: 10619465 DOI: 10.1016/s0306-4522(99)00410-8] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Magnetic resonance imaging and in vivo proton magnetic resonance spectroscopy were used to evaluate the therapeutic effect of lamotrigine and MK-801 on rat brain lesions induced by 3-nitropropionic acid. Systemic administration of 3-nitropropionic acid (15 mg/kg per day) to two-month-old Sprague-Dawley rats (n = 10 for each group) for five consecutive days induced selective striatal and hippocampal lesions and specific behavioral change. Pretreatment with lamotrigine (10 mg/kg or 20 mg/kg per day) or MK-801 (2 mg/kg per day) attenuated the lesions and behavioral change. There were no significant differences in T2 values of the striatum and hippocampus among rats pretreated with MK-801, lamotrigine (20 mg/kg) and sham controls. Significant elevations of succinate/creatine and lactate/creatine ratios and decreases of N-acetylaspartate/creatine and choline/creatine ratios were observed after 3-nitropropionic acid injections (P < 0.001). The changes were nearly prevented after pretreatment with lamotrigine (20 mg/kg). However, the N-acetylaspartate/creatine in rats pretreated with lamotrigine (10 mg/kg) (P < 0.01) and MK-801 (P < 0.05) still showed significant reduction as compared with sham controls. Thus we conclude that both lamotrigine and MK-801 are effective in attenuation of brain lesions induced by 3-nitropropionic acid. A higher dose of lamotrigine provides a better neuroprotective effect than MK-801. With a better therapeutic effect and fewer side effects, lamotrigine is more promising for potential clinical application.
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Affiliation(s)
- W T Lee
- Department of Pediatrics, College of Medicine, National Taiwan University, Taipei, Republic of China
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48
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Pedersen V, Schmidt WJ. The neuroprotectant properties of glutamate antagonists and antiglutamatergic drugs. Neurotox Res 2000; 2:179-204. [PMID: 16787840 DOI: 10.1007/bf03033793] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
In the slowly progressive neurodegenerative disorders like Parkinson's disease and Alzheimer's disease very different neuronal populations undergo degenerative processes, although the cascades of cellular events leading to death are supposed to be similar. We suggest that the complex pattern of degeneration in Parkinson's disease depends on two processes, a 'primary neurodegeneration' that takes place in the striato-nigral dopamine neurons and a 'secondary degeneration', occurring in distant structures of the basal ganglia network. For the purpose of explaining the regionally different expression of 'primary neurodegeneration' in different diseases, we postulate that the origin of neurodegeneration is associated with the local release of a neurotransmitter. For Parkinson's disease this would mean that the metabolism of dopamine in the striatum, nucleus accumbens and presumably the pedunculopontine tegmental nucleus, together with one or more pathological factors contribute to the initial neurodegeneration. There are recent studies indicating that a transneuronal retrograde degeneration of the substantia nigra pars compacta neurons might be induced by a loss of function of dopaminergic synapses in the striatum. We have recently established an animal model of retrograde striato-nigral degeneration, where the assessment of markers for cellular stress is possible. In Parkinson's disease, several structures distal from the substantia nigra pars compacta undergo neuropathological changes, characterizing the 'secondary neurodegeneration. Our recent studies provide experimental evidence for a chronic cellular stress in these structures because of a relative or absolute glutamatergic overactivity due to the initial loss of dopaminergic innervation. Thus, a loss of dopamine transforms the basal ganglia to a 'destructive network'. Both processes, the 'primary' and 'secondary neurodegeneration', affecting each other, characterize the progress of chronic neurodegeneration. From this point of view, we would further like to develop strategies for symptomatic amendment. Excitatory amino acids seem to be involved not only in the secondary processes of neurodegeneration, but also in initiation of the 'primary degeneration' of the substantia nigra pars compacta. Therefore, a reduction of glutamatergic overactivity constitutes a promising neuroprotective strategy. Especially the new antagonists of the NMDA-receptors with high affinity to the NR2B subunit of the receptor are in focus of our interest, since they reveal a favourable profile of side effects, therefore providing a promising tool for neuroprotection.
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Affiliation(s)
- V Pedersen
- Department of Neuropharmacology, University of Tübingen, Mohlstrasse 54/1, D-72074 Tübingen, Germany.
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49
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Malcolm CS, Benwell KR, Lamb H, Bebbington D, Porter RH. Characterization of iodoacetate-mediated neurotoxicity in vitro using primary cultures of rat cerebellar granule cells. Free Radic Biol Med 2000; 28:102-7. [PMID: 10656296 DOI: 10.1016/s0891-5849(99)00215-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The neuroprotective efficacy of antioxidant molecules against iodoacetate (IAA) neurotoxicity in rat cerebellar granule cell (CGC) cultures was investigated. Transient exposure to IAA caused a concentration-dependent decrease in cell viability (ED50 = 9.8 microM). Dizocilpine maleate (MK-801), and 1,2,3,4-tetrahydro-6-nitro-2,3-dioxobenzo[f]quinoxaline-7-sulfonamide (NBQX), failed to prevent IAA toxicity. Certain antioxidant molecules were shown to be neuroprotective against IAA when combined with MK-801 but were ineffective when administered alone. (S)-(-)-Trolox, butylated hydroxytoluene (BHT), and U-83836E exhibited EC50 values of 78, 5.9, and 0.25 microM, respectively, in the presence of 10 microM MK-801. IAA also induced an increase in intracellular oxidative stress, which was quenched by the antioxidants (in the presence of MK-801) in cultures loaded with the oxidant sensitive dye 2'7'-dichlorodihydrofluorescein diacetate (DCFH-DA).
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50
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Abstract
Mitochondria play a central role in the survival and death of neurons. The detailed bioenergetic mechanisms by which isolated mitochondria generate ATP, sequester Ca(2+), generate reactive oxygen species, and undergo Ca(2+)-dependent permeabilization of their inner membrane are currently being applied to the function of mitochondria in situ within neurons under physiological and pathophysiological conditions. Here we review the functional bioenergetics of isolated mitochondria, with emphasis on the chemiosmotic proton circuit and the application (and occasional misapplication) of these principles to intact neurons. Mitochondria play an integral role in both necrotic and apoptotic neuronal cell death, and the bioenergetic principles underlying current studies are reviewed.
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Affiliation(s)
- D G Nicholls
- Department of Pharmacology, University of Dundee, Dundee, Scotland.
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