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Skwarzynska D, Sun H, Kasprzak I, Sharma S, Williamson J, Kapur J. Glycolytic lactate production supports status epilepticus in experimental animals. Ann Clin Transl Neurol 2023; 10:1873-1884. [PMID: 37632130 PMCID: PMC10578888 DOI: 10.1002/acn3.51881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 07/27/2023] [Accepted: 08/09/2023] [Indexed: 08/27/2023] Open
Abstract
OBJECTIVE Status epilepticus (SE) requires rapid intervention to prevent cerebral injury and mortality. The ketogenic diet, which bypasses glycolysis, is a promising remedy for patients with refractory SE. We tested the role of glycolytic lactate production in sustaining SE. METHODS Extracellular lactate and glucose concentration during a seizure and SE in vivo was measured using lactate and glucose biosensors. A lactate dehydrogenase inhibitor, oxamate, blocked pyruvate to lactate conversion during SE. Video-EEG recordings evaluated seizure duration, severity, and immunohistochemistry was used to determine neuronal loss. Genetically encoded calcium indicator GCaMP7 was used to study the effect of oxamate on CA1 pyramidal neurons in vitro. Spontaneous excitatory postsynaptic currents (sEPSCs) were recorded from CA1 neurons to study oxamate's impact on neurotransmission. RESULTS The extracellular glucose concentration dropped rapidly during seizures, and lactate accumulated in the extracellular space. Inhibition of pyruvate to lactate conversion with oxamate terminated SE in mice. There was less neuronal loss in treated compared to control mice. Oxamate perfusion decreased tonic and phasic neuronal activity of GCaMP7-expressing CA1 pyramidal neurons in vitro. Oxamate application reduced the frequency, but not amplitude of sEPSCs recorded from CA1 neurons, suggesting an effect on the presynaptic glutamatergic neurotransmission. INTERPRETATION A single seizure and SE stimulate lactate production. Diminishing pyruvate to lactate conversion with oxamate terminated SE and reduced associated neuronal death. Oxamate reduced neuronal excitability and excitatory neurotransmission at the presynaptic terminal. Glycolytic lactate production sustains SE and is an attractive therapeutic target.
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Affiliation(s)
- Daria Skwarzynska
- Neuroscience Graduate ProgramUniversity of VirginiaCharlottesvilleVirginia22908USA
| | - Huayu Sun
- Department of NeurologyUniversity of VirginiaCharlottesvilleVirginia22908USA
| | - Izabela Kasprzak
- Department of NeurologyUniversity of VirginiaCharlottesvilleVirginia22908USA
| | - Supriya Sharma
- Department of NeurologyUniversity of VirginiaCharlottesvilleVirginia22908USA
| | - John Williamson
- Department of NeurologyUniversity of VirginiaCharlottesvilleVirginia22908USA
| | - Jaideep Kapur
- Department of NeurologyUniversity of VirginiaCharlottesvilleVirginia22908USA
- UVA Brain InstituteUniversity of VirginiaCharlottesvilleVirginia22908USA
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Multi-omics in mesial temporal lobe epilepsy with hippocampal sclerosis: Clues into the underlying mechanisms leading to disease. Seizure 2021; 90:34-50. [DOI: 10.1016/j.seizure.2021.03.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2020] [Revised: 02/26/2021] [Accepted: 03/02/2021] [Indexed: 02/07/2023] Open
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Ji W, Liu K, Zhao G, Wu F, Jiang Y, Hou L, Zhang M, Mao L. Electrochemical Sensing of Ascorbate as an Index of Neuroprotection from Seizure Activity by Physical Exercise in Freely Moving Rats. ACS Sens 2021; 6:546-552. [PMID: 33346640 DOI: 10.1021/acssensors.0c02326] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Physical exercise (PE) has been drawing increasing attention to prevent and alleviate neural damage of brain diseases; however, in vivo sensing of the neuroprotection ability of PE remains a challenge. Here, we find that ascorbate can be used as a small molecular index for neuroprotective function of PE and the neuroprotection ability of PE can thus be in vivo monitored with an online electrochemical system (OECS) in freely moving animals. With the OECS as the sensing system, we find that the concentration of ascorbate in the microdialysate from the striatum increases greatly in kainic acid (KA)-induced seizure rats and reaches twice the basal level (i.e., 214.4 ± 32.7%, p < 0.001, n = 4) at a time point 90 min after KA microinjection. Such an increase of ascorbate is obviously attenuated (i.e., 153.6 ± 23.9% of the basal level, p < 0.05, n = 3) after PE, showing the neuroprotective activity of PE. This finding is believed to be significant in providing chemical insight into the neuroprotection ability of PE.
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Affiliation(s)
- Wenliang Ji
- Department of Chemistry, Renmin University of China, Beijing 100872, China
| | - Kun Liu
- Capital University of Physical Education and Sports, Beijing 100191, China
| | - Gang Zhao
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, the Chinese Academy of Sciences (CAS), Beijing 100190, China
| | - Fei Wu
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, the Chinese Academy of Sciences (CAS), Beijing 100190, China
| | | | | | - Meining Zhang
- Department of Chemistry, Renmin University of China, Beijing 100872, China
| | - Lanqun Mao
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, the Chinese Academy of Sciences (CAS), Beijing 100190, China
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Oses JP, Müller AP, Strogulski NR, Moreira JD, Böhmer AE, Hansel G, Carteri RB, Busnello JV, Kopczynski A, Rodolphi MS, Souza DO, Portela LV. Sustained elevation of cerebrospinal fluid glucose and lactate after a single seizure does not parallel with mitochondria energy production. Epilepsy Res 2019; 152:35-41. [PMID: 30875635 DOI: 10.1016/j.eplepsyres.2019.03.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Revised: 02/18/2019] [Accepted: 03/09/2019] [Indexed: 12/22/2022]
Abstract
Generalized seizures trigger excessive neuronal firing that imposes large demands on the brain glucose/lactate availability and utilization, which synchronization requires an integral mitochondrial oxidative capability. We investigated whether a single convulsive crisis affects brain glucose/lactate availability and mitochondrial energy production. Adult male Wistar rats received a single injection of pentylentetrazol (PTZ, 60 mg/kg, i.p.) or saline. The cerebrospinal fluid (CSF) levels of glucose and lactate, mitochondrial respirometry, [14C]-2-deoxy-D-glucose uptake, glycogen content and cell viability in hippocampus were measured. CSF levels of glucose and lactate (mean ± SD) in control animals were 68.08 ± 11.62 mg/dL and 1.17 ± 0.32 mmol/L, respectively. Tonic-clonic seizures increased glucose levels at 10 min (96.25 ± 13.19) peaking at 60 min (113.03 ± 16.34) returning to control levels at 24 h (50.12 ± 12.81), while lactate increased at 10 min (3.23 ± 1.57) but returned to control levels at 360 min after seizures (1.58 ± 0.21). The hippocampal [14C]-2-deoxy-D-glucose uptake, glycogen content, and cell viability decreased up to 60 min after the seizures onset. Also, an uncoupling between mitochondrial oxygen consumption and ATP synthesis via FoF1-ATP synthase was observed at 10 min, 60 min and 24 h after seizures. In summary, after a convulsive seizure glucose and lactate levels immediately rise within the brain, however, considering the acute impact of this metabolic crisis, mitochondria are not able to increase energy production thereby affecting cell viability.
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Affiliation(s)
- Jean Pierre Oses
- Programa de Pós-graduação em Ciências Biológicas, Bioquímica, Laboratório de Neurotrauma e Biomarcadores, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Alexandre Pastoris Müller
- Unidade de Ciências da Saúde, Laboratório de Bioquímica e Fisiologia do Exercício Universidade do Extremo Sul Catarinense-UNESC, Av. Universitária, 1105 - Bairro Universitário, CEP 88806-000, Criciúma, Santa Catarina, Brazil
| | - Nathan Ryzewski Strogulski
- Programa de Pós-graduação em Ciências Biológicas, Bioquímica, Laboratório de Neurotrauma e Biomarcadores, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Julia D Moreira
- Programa de Pós-graduação em Ciências Biológicas, Bioquímica, Laboratório de Neurotrauma e Biomarcadores, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil; Departamento de Nutrição, Universidade Federal de Santa Catarina, Florianópolis, Brazil
| | - Ana Elisa Böhmer
- Programa de Pós-graduação em Ciências Biológicas, Bioquímica, Laboratório de Neurotrauma e Biomarcadores, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Gisele Hansel
- Programa de Pós-graduação em Ciências Biológicas, Bioquímica, Laboratório de Neurotrauma e Biomarcadores, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Randhall Bruce Carteri
- Programa de Pós-graduação em Ciências Biológicas, Bioquímica, Laboratório de Neurotrauma e Biomarcadores, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - João Vicente Busnello
- Department of Psychiatry and Behavioral Neuroscience, University of Chicago, Chicago, IL, USA
| | - Afonso Kopczynski
- Programa de Pós-graduação em Ciências Biológicas, Bioquímica, Laboratório de Neurotrauma e Biomarcadores, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Marcelo Salimen Rodolphi
- Programa de Pós-graduação em Ciências Biológicas, Bioquímica, Laboratório de Neurotrauma e Biomarcadores, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Diogo Onofre Souza
- Programa de Pós-graduação em Ciências Biológicas, Bioquímica, Laboratório de Neurotrauma e Biomarcadores, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Luis Valmor Portela
- Programa de Pós-graduação em Ciências Biológicas, Bioquímica, Laboratório de Neurotrauma e Biomarcadores, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
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Bazzigaluppi P, Ebrahim Amini A, Weisspapir I, Stefanovic B, Carlen PL. Hungry Neurons: Metabolic Insights on Seizure Dynamics. Int J Mol Sci 2017; 18:ijms18112269. [PMID: 29143800 PMCID: PMC5713239 DOI: 10.3390/ijms18112269] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 10/24/2017] [Accepted: 10/26/2017] [Indexed: 12/18/2022] Open
Abstract
Epilepsy afflicts up to 1.6% of the population and the mechanisms underlying the appearance of seizures are still not understood. In past years, many efforts have been spent trying to understand the mechanisms underlying the excessive and synchronous firing of neurons. Traditionally, attention was pointed towards synaptic (dys)function and extracellular ionic species (dys)regulation. Recently, novel clinical and preclinical studies explored the role of brain metabolism (i.e., glucose utilization) of seizures pathophysiology revealing (in most cases) reduced metabolism in the inter-ictal period and increased metabolism in the seconds preceding and during the appearance of seizures. In the present review, we summarize the clinical and preclinical observations showing metabolic dysregulation during epileptogenesis, seizure initiation, and termination, and in the inter-ictal period. Recent preclinical studies have shown that 2-Deoxyglucose (2-DG, a glycolysis blocker) is a novel therapeutic approach to reduce seizures. Furthermore, we present initial evidence for the effectiveness of 2-DG in arresting 4-Aminopyridine induced neocortical seizures in vivo in the mouse.
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Affiliation(s)
- Paolo Bazzigaluppi
- Krembil Research Institute, Fundamental Neurobiology, Toronto, ON M5T 2S8, Canada.
- Sunnybrook Research Institute, Medical Biophysics, Toronto, ON M4N 3M5, Canada.
| | - Azin Ebrahim Amini
- Krembil Research Institute, Fundamental Neurobiology, Toronto, ON M5T 2S8, Canada.
- Institute of Biomaterials & Biomedical Engineering (IBBME), University of Toronto, Toronto, ON M5S 3G9, Canada.
| | - Iliya Weisspapir
- Krembil Research Institute, Fundamental Neurobiology, Toronto, ON M5T 2S8, Canada.
| | - Bojana Stefanovic
- Sunnybrook Research Institute, Medical Biophysics, Toronto, ON M4N 3M5, Canada.
| | - Peter L Carlen
- Krembil Research Institute, Fundamental Neurobiology, Toronto, ON M5T 2S8, Canada.
- Department of Medicine & Physiology, and Institute of Biomaterials & Biomedical Engineering (IBBME), University of Toronto, Toronto, ON M5S 1A8, Canada.
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Imran I, Hillert MH, Klein J. Early metabolic responses to lithium/pilocarpine-induced status epilepticus in rat brain. J Neurochem 2015; 135:1007-18. [DOI: 10.1111/jnc.13360] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Revised: 08/25/2015] [Accepted: 08/29/2015] [Indexed: 01/04/2023]
Affiliation(s)
- Imran Imran
- Department of Pharmacology; School of Pharmacy; Biocenter N260; Goethe University Frankfurt; Frankfurt am Main Germany
- Faculty of Pharmacy; Bahauddin Zakariya University; Multan Pakistan
| | - Markus H. Hillert
- Department of Pharmacology; School of Pharmacy; Biocenter N260; Goethe University Frankfurt; Frankfurt am Main Germany
| | - Jochen Klein
- Department of Pharmacology; School of Pharmacy; Biocenter N260; Goethe University Frankfurt; Frankfurt am Main Germany
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Inhibition of brain swelling after ischemia-reperfusion by β-adrenergic antagonists: correlation with increased K+ and decreased Ca2+ concentrations in extracellular fluid. BIOMED RESEARCH INTERNATIONAL 2014; 2014:873590. [PMID: 25478577 PMCID: PMC4247955 DOI: 10.1155/2014/873590] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2014] [Revised: 09/03/2014] [Accepted: 09/10/2014] [Indexed: 12/11/2022]
Abstract
Infarct size and brain edema following ischemia/reperfusion are reduced by inhibitors of the Na+, K+, 2Cl−, and water cotransporter NKCC1 and by β1-adrenoceptor antagonists. NKCC1 is a secondary active transporter, mainly localized in astrocytes, driven by transmembrane Na+/K+ gradients generated by the Na+,K+-ATPase. The astrocytic Na+,K+-ATPase is stimulated by small increases in extracellular K+ concentration and by the β-adrenergic agonist isoproterenol. Larger K+ increases, as occurring during ischemia, also stimulate NKCC1, creating cell swelling. This study showed no edema after 3 hr medial cerebral artery occlusion but pronounced edema after 8 hr reperfusion. The edema was abolished by inhibitors of specifically β1-adrenergic pathways, indicating failure of K+-mediated, but not β1-adrenoceptor-mediated, stimulation of Na+,K+-ATPase/NKCC1 transport during reoxygenation. Ninety percent reduction of extracellular Ca2+ concentration occurs in ischemia. Ca2+ omission abolished K+ uptake in normoxic cultures of astrocytes after addition of 5 mM KCl. A large decrease in ouabain potency on K+ uptake in cultured astrocytes was also demonstrated in Ca2+-depleted media, and endogenous ouabains are needed for astrocytic K+ uptake. Thus, among the ionic changes induced by ischemia, the decrease in extracellular Ca2+ causes failure of the high-K+-stimulated Na+,K+-ATPase/NKCC1 ion/water uptake, making β1-adrenergic activation the only stimulus and its inhibition effective against edema.
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8
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Larach DB, Kofke WA, Le Roux P. Potential non-hypoxic/ischemic causes of increased cerebral interstitial fluid lactate/pyruvate ratio: a review of available literature. Neurocrit Care 2012; 15:609-22. [PMID: 21336786 DOI: 10.1007/s12028-011-9517-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Microdialysis, an in vivo technique that permits collection and analysis of small molecular weight substances from the interstitial space, was developed more than 30 years ago and introduced into the clinical neurosciences in the 1990s. Today cerebral microdialysis is an established, commercially available clinical tool that is focused primarily on markers of cerebral energy metabolism (glucose, lactate, and pyruvate) and cell damage (glycerol), and neurotransmitters (glutamate). Although the brain comprises only 2% of body weight, it consumes 20% of total body energy. Consequently, the ability to monitor cerebral metabolism can provide significant insights during clinical care. Measurements of lactate, pyruvate, and glucose give information about the comparative contributions of aerobic and anaerobic metabolisms to brain energy. The lactate/pyruvate ratio reflects cytoplasmic redox state and thus provides information about tissue oxygenation. An elevated lactate pyruvate ratio (>40) frequently is interpreted as a sign of cerebral hypoxia or ischemia. However, several other factors may contribute to an elevated LPR. This article reviews potential non-hypoxic/ischemic causes of an increased LPR.
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Affiliation(s)
- Daniel B Larach
- University of Pennsylvania School of Medicine, Philadelphia, PA, USA.
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9
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Darbin O, Risso J, Carre E, Lonjon M, Naritoku D. Striatal energetic homeostasis under anaesthetic conditions. Brain Res 2011; 1388:157-66. [DOI: 10.1016/j.brainres.2011.03.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Revised: 03/03/2011] [Accepted: 03/03/2011] [Indexed: 10/18/2022]
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Pozdnyakova N, Yatsenko L, Parkhomenko N, Himmelreich N. Perinatal hypoxia induces a long-lasting increase in unstimulated gaba release in rat brain cortex and hippocampus. The protective effect of pyruvate. Neurochem Int 2011; 58:14-21. [DOI: 10.1016/j.neuint.2010.10.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Accepted: 10/14/2010] [Indexed: 10/18/2022]
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11
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Changes in mouse brain metabolism following a convulsive dose of soman: A proton HRMAS NMR study. Toxicology 2010; 267:99-111. [DOI: 10.1016/j.tox.2009.10.026] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2009] [Revised: 10/20/2009] [Accepted: 10/21/2009] [Indexed: 11/20/2022]
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12
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Carmody S, Brennan L. Effects of pentylenetetrazole-induced seizures on metabolomic profiles of rat brain. Neurochem Int 2009; 56:340-4. [PMID: 19913064 DOI: 10.1016/j.neuint.2009.11.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2009] [Revised: 11/02/2009] [Accepted: 11/06/2009] [Indexed: 11/18/2022]
Abstract
Epilepsy is one of the most common neurological disorders and approximately one-third of patients with epilepsy are resistant to treatment. In order to develop our understanding of the metabolic changes occurring during seizure a metabolomic approach was employed. Using a pentylenetetrazole (PTZ) kindling model of epilepsy metabolomic analysis of brain extracts from the cerebellum, brain stem, prefrontal cortex and hippocampus was performed. Principal component analysis (PCA) of the (1)H NMR derived data revealed a distinct metabolic profile for each brain region. In order to assess the changes occurring following seizure partial least square discriminant analysis (PLS-DA) models for each brain region for PTZ-kindled and control animals were constructed. For all the brain regions good predictive models were built and the discriminating metabolites were identified. Results following one injection of PTZ indicated that the changes observed in the cerebellum and hippocampus were mainly due to seizure. In the hippocampus of PTZ-kindled animals the metabolites changing included lactate, succinate, GABA, NAA, choline and taurine. Analysis of the cerebellum of PTZ-kindled animals revealed changes in lactate, myo-inositol, choline, GABA, creatine, succinate, phosphocholine and GPC. Overall, the results indicate that seizure may be associated with an increase in energy demand, altered neurotransmitter balance and an increase in neuronal loss and gliosis.
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Affiliation(s)
- Stacey Carmody
- UCD School of Agriculture, Food Science and Veterinary Medicine, UCD Conway Institute, University College Dublin (UCD), Dublin 4, Ireland
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Brain metabolism and diffusion in the rat cerebral cortex during pilocarpine-induced status epilepticus. Exp Neurol 2008; 209:145-54. [DOI: 10.1016/j.expneurol.2007.09.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2007] [Revised: 08/13/2007] [Accepted: 09/11/2007] [Indexed: 11/19/2022]
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Liu W, Gnanasambandam R, Benjamin J, Kaur G, Getman PB, Siegel AJ, Shortridge RD, Singh S. Mutations in cytochrome c oxidase subunit VIa cause neurodegeneration and motor dysfunction in Drosophila. Genetics 2007; 176:937-46. [PMID: 17435251 PMCID: PMC1894620 DOI: 10.1534/genetics.107.071688] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Mitochondrial dysfunction is involved in many neurodegenerative disorders in humans. Here we report mutations in a gene (designated levy) that codes for subunit VIa of cytochrome c oxidase (COX). The mutations were identified by the phenotype of temperature-induced paralysis and showed the additional phenotypes of decreased COX activity, age-dependent bang-induced paralysis, progressive neurodegeneration, and reduced life span. Germ-line transformation using the levy(+) gene rescued the mutant flies from all phenotypes including neurodegeneration. The data from levy mutants reveal a COX-mediated pathway in Drosophila, disruption of which leads to mitochondrial encephalomyopathic effects including neurodegeneration, motor dysfunction, and premature death. The data present the first case of a mutation in a nuclear-encoded structural subunit of COX that causes mitochondrial encephalomyopathy rather than lethality, whereas several previous attempts to identify such mutations have not been successful. The levy mutants provide a genetic model to understand the mechanisms underlying COX-mediated mitochondrial encephalomyopathies and to explore possible therapeutic interventions.
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Affiliation(s)
- Wensheng Liu
- Department of Pharmacology and Toxicology, State University of New York, Buffalo, New York 14214 and Department of Biological Sciences, State University of New York, Buffalo, New York 14260
| | - Radhakrishnan Gnanasambandam
- Department of Pharmacology and Toxicology, State University of New York, Buffalo, New York 14214 and Department of Biological Sciences, State University of New York, Buffalo, New York 14260
| | - Jeffery Benjamin
- Department of Pharmacology and Toxicology, State University of New York, Buffalo, New York 14214 and Department of Biological Sciences, State University of New York, Buffalo, New York 14260
| | - Gunisha Kaur
- Department of Pharmacology and Toxicology, State University of New York, Buffalo, New York 14214 and Department of Biological Sciences, State University of New York, Buffalo, New York 14260
| | - Patricia B. Getman
- Department of Pharmacology and Toxicology, State University of New York, Buffalo, New York 14214 and Department of Biological Sciences, State University of New York, Buffalo, New York 14260
| | - Alan J. Siegel
- Department of Pharmacology and Toxicology, State University of New York, Buffalo, New York 14214 and Department of Biological Sciences, State University of New York, Buffalo, New York 14260
| | - Randall D. Shortridge
- Department of Pharmacology and Toxicology, State University of New York, Buffalo, New York 14214 and Department of Biological Sciences, State University of New York, Buffalo, New York 14260
| | - Satpal Singh
- Department of Pharmacology and Toxicology, State University of New York, Buffalo, New York 14214 and Department of Biological Sciences, State University of New York, Buffalo, New York 14260
- Corresponding author: Department of Pharmacology and Toxicology, 102 Farber Hall, State University of New York, Buffalo, NY 14214-3000. E-mail:
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Cerdán S, Rodrigues TB, Sierra A, Benito M, Fonseca LL, Fonseca CP, García-Martín ML. The redox switch/redox coupling hypothesis. Neurochem Int 2006; 48:523-30. [PMID: 16530294 DOI: 10.1016/j.neuint.2005.12.036] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2005] [Revised: 12/07/2005] [Accepted: 12/09/2005] [Indexed: 10/24/2022]
Abstract
We provide an integrative interpretation of neuroglial metabolic coupling including the presence of subcellular compartmentation of pyruvate and monocarboxylate recycling through the plasma membrane of both neurons and glial cells. The subcellular compartmentation of pyruvate allows neurons and astrocytes to select between glucose and lactate as alternative substrates, depending on their relative extracellular concentration and the operation of a redox switch. This mechanism is based on the inhibition of glycolysis at the level of glyceraldehyde 3-phosphate dehydrogenase by NAD(+) limitation, under sufficiently reduced cytosolic NAD(+)/NADH redox conditions. Lactate and pyruvate recycling through the plasma membrane allows the return to the extracellular medium of cytosolic monocarboxylates enabling their transcellular, reversible, exchange between neurons and astrocytes. Together, intracellular pyruvate compartmentation and monocarboxylate recycling result in an effective transcellular coupling between the cytosolic NAD(+)/NADH redox states of both neurons and glial cells. Following glutamatergic neurotransmission, increased glutamate uptake by the astrocytes is proposed to augment glycolysis and tricarboxylic acid cycle activity, balancing to a reduced cytosolic NAD(+)/NADH in the glia. Reducing equivalents are transferred then to the neuron resulting in a reduced neuronal NAD(+)/NADH redox state. This may eventually switch off neuronal glycolysis, favoring the oxidation of extracellular lactate in the lactate dehydrogenase (LDH) equilibrium and in the neuronal tricarboxylic acid cycles. Finally, pyruvate derived from neuronal lactate oxidation, may return to the extracellular space and to the astrocyte, restoring the basal redox state and beginning a new loop of the lactate/pyruvate transcellular coupling cycle. Transcellular redox coupling operates through the plasma membrane transporters of monocarboxylates, similarly to the intracellular redox shuttles coupling the cytosolic and mitochondrial redox states through the transporters of the inner mitochondrial membrane. Finally, transcellular redox coupling mechanisms may couple glycolytic and oxidative zones in other heterogeneous tissues including muscle and tumors.
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Affiliation(s)
- Sebastián Cerdán
- Laboratory for Imaging and Spectroscopy by Magnetic Resonance LISMAR, Institute of Biomedical Research Alberto Sols, c/Arturo Duperier 4, E-28029 Madrid, Spain
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