1
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Dienel GA, Rothman DL. In vivo calibration of genetically encoded metabolite biosensors must account for metabolite metabolism during calibration and cellular volume. J Neurochem 2024; 168:506-532. [PMID: 36726217 DOI: 10.1111/jnc.15775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 01/21/2023] [Accepted: 01/28/2023] [Indexed: 02/03/2023]
Abstract
Isotopic assays of brain glucose utilization rates have been used for more than four decades to establish relationships between energetics, functional activity, and neurotransmitter cycling. Limitations of these methods include the relatively long time (1-60 min) for the determination of labeled metabolite levels and the lack of cellular resolution. Identification and quantification of fuels for neurons and astrocytes that support activation and higher brain functions are a major, unresolved issues. Glycolysis is preferentially up-regulated during activation even though oxygen level and supply are adequate, causing lactate concentrations to quickly rise during alerting, sensory processing, cognitive tasks, and memory consolidation. However, the fate of lactate (rapid release from brain or cell-cell shuttling coupled with local oxidation) is long disputed. Genetically encoded biosensors can determine intracellular metabolite concentrations and report real-time lactate level responses to sensory, behavioral, and biochemical challenges at the cellular level. Kinetics and time courses of cellular lactate concentration changes are informative, but accurate biosensor calibration is required for quantitative comparisons of lactate levels in astrocytes and neurons. An in vivo calibration procedure for the Laconic lactate biosensor involves intracellular lactate depletion by intravenous pyruvate-mediated trans-acceleration of lactate efflux followed by sensor saturation by intravenous infusion of high doses of lactate plus ammonium chloride. In the present paper, the validity of this procedure is questioned because rapid lactate-pyruvate interconversion in blood, preferential neuronal oxidation of both monocarboxylates, on-going glycolytic metabolism, and cellular volumes were not taken into account. Calibration pitfalls for the Laconic lactate biosensor also apply to other metabolite biosensors that are standardized in vivo by infusion of substrates that can be metabolized in peripheral tissues. We discuss how technical shortcomings negate the conclusion that Laconic sensor calibrations support the existence of an in vivo astrocyte-neuron lactate concentration gradient linked to lactate shuttling from astrocytes to neurons to fuel neuronal activity.
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Affiliation(s)
- Gerald A Dienel
- Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
- Department of Cell Biology and Physiology, University of New Mexico School of Medicine, Albuquerque, New Mexico, USA
| | - Douglas L Rothman
- Magnetic Resonance Research Center and Departments of Radiology and Biomedical Engineering, Yale University, New Haven, Connecticut, USA
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2
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Rae CD, Baur JA, Borges K, Dienel G, Díaz-García CM, Douglass SR, Drew K, Duarte JMN, Duran J, Kann O, Kristian T, Lee-Liu D, Lindquist BE, McNay EC, Robinson MB, Rothman DL, Rowlands BD, Ryan TA, Scafidi J, Scafidi S, Shuttleworth CW, Swanson RA, Uruk G, Vardjan N, Zorec R, McKenna MC. Brain energy metabolism: A roadmap for future research. J Neurochem 2024; 168:910-954. [PMID: 38183680 PMCID: PMC11102343 DOI: 10.1111/jnc.16032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2023] [Revised: 11/29/2023] [Accepted: 12/05/2023] [Indexed: 01/08/2024]
Abstract
Although we have learned much about how the brain fuels its functions over the last decades, there remains much still to discover in an organ that is so complex. This article lays out major gaps in our knowledge of interrelationships between brain metabolism and brain function, including biochemical, cellular, and subcellular aspects of functional metabolism and its imaging in adult brain, as well as during development, aging, and disease. The focus is on unknowns in metabolism of major brain substrates and associated transporters, the roles of insulin and of lipid droplets, the emerging role of metabolism in microglia, mysteries about the major brain cofactor and signaling molecule NAD+, as well as unsolved problems underlying brain metabolism in pathologies such as traumatic brain injury, epilepsy, and metabolic downregulation during hibernation. It describes our current level of understanding of these facets of brain energy metabolism as well as a roadmap for future research.
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Affiliation(s)
- Caroline D. Rae
- School of Psychology, The University of New South Wales, NSW 2052 & Neuroscience Research Australia, Randwick, New South Wales, Australia
| | - Joseph A. Baur
- Department of Physiology and Institute for Diabetes, Obesity and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Karin Borges
- School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, St Lucia, QLD, Australia
| | - Gerald Dienel
- Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
- Department of Cell Biology and Physiology, University of New Mexico School of Medicine, Albuquerque, New Mexico, USA
| | - Carlos Manlio Díaz-García
- Department of Biochemistry and Molecular Biology, Center for Geroscience and Healthy Brain Aging, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | | | - Kelly Drew
- Center for Transformative Research in Metabolism, Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, Alaska, USA
| | - João M. N. Duarte
- Department of Experimental Medical Science, Faculty of Medicine, Lund University, Lund, & Wallenberg Centre for Molecular Medicine, Lund University, Lund, Sweden
| | - Jordi Duran
- Institut Químic de Sarrià (IQS), Universitat Ramon Llull (URL), Barcelona, Spain
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Oliver Kann
- Institute of Physiology and Pathophysiology, University of Heidelberg, D-69120; Interdisciplinary Center for Neurosciences (IZN), University of Heidelberg, Heidelberg, Germany
| | - Tibor Kristian
- Veterans Affairs Maryland Health Center System, Baltimore, Maryland, USA
- Department of Anesthesiology and the Center for Shock, Trauma, and Anesthesiology Research (S.T.A.R.), University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Dasfne Lee-Liu
- Facultad de Medicina y Ciencia, Universidad San Sebastián, Santiago, Región Metropolitana, Chile
| | - Britta E. Lindquist
- Department of Neurology, Division of Neurocritical Care, Gladstone Institute of Neurological Disease, University of California at San Francisco, San Francisco, California, USA
| | - Ewan C. McNay
- Behavioral Neuroscience, University at Albany, Albany, New York, USA
| | - Michael B. Robinson
- Departments of Pediatrics and System Pharmacology & Translational Therapeutics, Children’s Hospital of Philadelphia, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Douglas L. Rothman
- Magnetic Resonance Research Center and Departments of Radiology and Biomedical Engineering, Yale University, New Haven, Connecticut, USA
| | - Benjamin D. Rowlands
- School of Chemistry, Faculty of Science, The University of Sydney, Sydney, New South Wales, Australia
| | - Timothy A. Ryan
- Department of Biochemistry, Weill Cornell Medicine, New York, New York, USA
| | - Joseph Scafidi
- Department of Neurology, Kennedy Krieger Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Susanna Scafidi
- Anesthesiology & Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - C. William Shuttleworth
- Department of Neurosciences, University of New Mexico School of Medicine Albuquerque, Albuquerque, New Mexico, USA
| | - Raymond A. Swanson
- Department of Neurology, University of California, San Francisco, and San Francisco Veterans Affairs Medical Center, San Francisco, California, USA
| | - Gökhan Uruk
- Department of Neurology, University of California, San Francisco, and San Francisco Veterans Affairs Medical Center, San Francisco, California, USA
| | - Nina Vardjan
- Laboratory of Cell Engineering, Celica Biomedical, Ljubljana, Slovenia
- Laboratory of Neuroendocrinology—Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Robert Zorec
- Laboratory of Cell Engineering, Celica Biomedical, Ljubljana, Slovenia
- Laboratory of Neuroendocrinology—Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Mary C. McKenna
- Department of Pediatrics and Program in Neuroscience, University of Maryland School of Medicine, Baltimore, Maryland, USA
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Costa-Pinto S, Gonçalves-Ribeiro J, Tedim-Moreira J, Socodato R, Relvas JB, Sebastião AM, Vaz SH. Communication defects with astroglia contribute to early impairments in the motor cortex plasticity of SOD1 G93A mice. Neurobiol Dis 2024; 193:106435. [PMID: 38336279 DOI: 10.1016/j.nbd.2024.106435] [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: 10/13/2023] [Revised: 02/06/2024] [Accepted: 02/06/2024] [Indexed: 02/12/2024] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease, involving the selective degeneration of cortical upper synapses in the primary motor cortex (M1). Excitotoxicity in ALS occurs due to an imbalance between excitation and inhibition, closely linked to the loss/gain of astrocytic function. Using the ALS SOD1G93A mice, we investigated the astrocytic contribution for the electrophysiological alterations observed in the M1 of SOD1G93A mice, throughout disease progression. Results showed that astrocytes are involved in synaptic dysfunction observed in presymptomatic SOD1G93A mice, since astrocytic glutamate transport currents are diminished and pharmacological inhibition of astrocytes only impaired long-term potentiation and basal transmission in wild-type mice. Proteomic analysis revealed major differences in neuronal transmission, metabolism, and immune system in upper synapses, confirming early communication deficits between neurons and astroglia. These results provide valuable insights into the early impact of upper synapses in ALS and the lack of supportive functions of cortical astrocytes, highlighting the possibility of manipulating astrocytes to improve synaptic function.
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Affiliation(s)
- Sara Costa-Pinto
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisbon, Portugal; Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon 1649-028, Portugal
| | - Joana Gonçalves-Ribeiro
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisbon, Portugal; Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon 1649-028, Portugal
| | - Joana Tedim-Moreira
- Instituto de Investigação e Inovação em Saúde and Instituto de Biologia Molecular e Celular (IBMC), University of Porto, Porto 4200-135, Portugal; Department of Biomedicine, Faculty of Medicine, University of Porto, Porto 4200-135, Portugal
| | - Renato Socodato
- Instituto de Investigação e Inovação em Saúde and Instituto de Biologia Molecular e Celular (IBMC), University of Porto, Porto 4200-135, Portugal
| | - João B Relvas
- Instituto de Investigação e Inovação em Saúde and Instituto de Biologia Molecular e Celular (IBMC), University of Porto, Porto 4200-135, Portugal; Department of Biomedicine, Faculty of Medicine, University of Porto, Porto 4200-135, Portugal
| | - Ana M Sebastião
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisbon, Portugal; Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon 1649-028, Portugal
| | - Sandra H Vaz
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisbon, Portugal; Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon 1649-028, Portugal.
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Adermark L, Stomberg R, Söderpalm B, Ericson M. Astrocytic Regulation of Endocannabinoid-Dependent Synaptic Plasticity in the Dorsolateral Striatum. Int J Mol Sci 2024; 25:581. [PMID: 38203752 PMCID: PMC10779090 DOI: 10.3390/ijms25010581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 12/26/2023] [Accepted: 12/28/2023] [Indexed: 01/12/2024] Open
Abstract
Astrocytes are pivotal for synaptic transmission and may also play a role in the induction and expression of synaptic plasticity, including endocannabinoid-mediated long-term depression (eCB-LTD). In the dorsolateral striatum (DLS), eCB signaling plays a major role in balancing excitation and inhibition and promoting habitual learning. The aim of this study was to outline the role of astrocytes in regulating eCB signaling in the DLS. To this end, we employed electrophysiological slice recordings combined with metabolic, chemogenetic and pharmacological approaches in an attempt to selectively suppress astrocyte function. High-frequency stimulation induced eCB-mediated LTD (HFS-LTD) in brain slices from both male and female rats. The metabolic uncoupler fluorocitrate (FC) reduced the probability of transmitter release and depressed synaptic output in a manner that was independent on cannabinoid 1 receptor (CB1R) activation. Fluorocitrate did not affect the LTD induced by the CB1R agonist WIN55,212-2, but enhanced CB1R-dependent HFS-LTD. Reduced neurotransmission and facilitated HFS-LTD were also observed during chemogenetic manipulation using Gi-coupled DREADDs targeting glial fibrillary acidic protein (GFAP)-expressing cells, during the pharmacological inhibition of connexins using carbenoxolone disodium, or during astrocytic glutamate uptake using TFB-TBOA. While pretreatment with the N-methyl-D-aspartate (NMDA) receptor antagonist 2-amino-5-phosphonopentanoic acid (APV) failed to prevent synaptic depression induced by FC, it blocked the facilitation of HFS-LTD. While the lack of tools to disentangle astrocytes from neurons is a major limitation of this study, our data collectively support a role for astrocytes in modulating basal neurotransmission and eCB-mediated synaptic plasticity.
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Affiliation(s)
- Louise Adermark
- Department of Pharmacology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, 40530 Gothenburg, Sweden
| | - Rosita Stomberg
- Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, 40530 Gothenburg, Sweden; (R.S.); (B.S.); (M.E.)
| | - Bo Söderpalm
- Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, 40530 Gothenburg, Sweden; (R.S.); (B.S.); (M.E.)
- Beroendekliniken, Sahlgrenska University Hospital, 41345 Gothenburg, Sweden
| | - Mia Ericson
- Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, 40530 Gothenburg, Sweden; (R.S.); (B.S.); (M.E.)
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5
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Storm-Mathisen J, Johnston GAR. In memoriam: Frode Fonnum (1937-2023). J Neurochem 2023; 167:711-715. [PMID: 37859335 DOI: 10.1111/jnc.15973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Accepted: 09/13/2023] [Indexed: 10/21/2023]
Abstract
Frode Fonnum died unexpectedly on 26th April 2023, at 86 years of age. He was a tower of strength-a primeval force-in neuroscience, neurochemistry and toxicology. His highly cited publications, comprised salient evidence for GABA and glutamate as brain neurotransmitters. He served as an expert, and as an organizer, including of European research cooperation and as President of the International Society for Neurochemistry (ISN). Photo credit: Per Kristian Opstad.
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Affiliation(s)
| | - Graham A R Johnston
- Sydney Pharmacy School, University of Sydney, Sydney, New South Wales, Australia
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Song H, Lu Z, Zhan K, Datsomor O, Ma X, Yang T, Chen Y, Jiang M, Zhao G. Effects of Glucose Levels on Inflammation and Amino Acid Utilization in Lipopolysaccharide-Induced Bovine Mammary Epithelial Cells. Animals (Basel) 2023; 13:3494. [PMID: 38003112 PMCID: PMC10668840 DOI: 10.3390/ani13223494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 10/28/2023] [Accepted: 11/06/2023] [Indexed: 11/26/2023] Open
Abstract
Glucose and amino acids are important sources of nutrients in the synthetic milk of dairy cows, and understanding the fate of amino acids is essential to optimize the utilization of amino acids in milk protein synthesis, thereby reducing nutrient inefficiencies during lactation. The purpose of this study was to investigate the effects of LPS and different concentrations of glucose on (1) the expression of inflammatory factors and genes, (2) the glucose metabolism, and (3) amino acid utilization in BMECs. The results showed that there was an interaction (LPS × glucose, p < 0.05) between LPS and glucose content in the inflammatory cytokine genes (IL-6 and TNF-α) and the inflammatory regulatory genes (CXCL2, CXCL8, and CCL5). With the addition of LPS, the HG + LPS group caused downregulated (p < 0.05) expression of IL-6 and TNF-α, compared with the LG + LPS group. Interestingly, compared with the LG + LPS group, the HG + LPS group upregulated (p < 0.05) the expression of CXCL2, CXCL8, and CCL5. LPS supplementation increased (p = 0.056) the consumption of glucose and GLUT1 gene expression (p < 0.05) and tended to increase (p = 0.084) the LDHA gene expression of BMECs under conditions of different concentrations of glucose culture. High glucose content increased (p < 0.001) the consumption of glucose and enhanced (p < 0.05) the GLUT1, HK1, HK2, and LDHA gene expression of BMECs with or without LPS incubation, and there was an interaction (LPS × glucose, p < 0.05) between LPS and glucose concentrations in GLUT1 gene expression. In this study, LPS enhanced (p < 0.05) the consumption of amino acids such as tryptophan, leucine, isoleucine, methionine, valine, histidine, and glutamate, while high levels of glucose decreased (p < 0.01) consumption, except in the case of tyrosine. For histidine, leucine, isoleucine, and valine consumption, there was an interaction (LPS × glucose, p < 0.05) between LPS and glucose levels. Overall, these findings suggest that relatively high glucose concentrations may lessen the LPS-induced BMEC inflammatory response and reduce amino acid consumption, while low glucose concentrations may increase the demand for most amino acids through proinflammatory responses.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Guoqi Zhao
- College of Animal Science and Technology, Yangzhou University, Yangzhou 225009, China; (H.S.); (Z.L.); (K.Z.); (O.D.); (X.M.); (T.Y.); (Y.C.); (M.J.)
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7
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Nitric Oxide Linked to mGluR5 Upregulates BDNF Synthesis by Activating MMP2 in the Caudate and Putamen after Challenge Exposure to Nicotine in Rats. Int J Mol Sci 2022; 23:ijms231810950. [PMID: 36142895 PMCID: PMC9505196 DOI: 10.3390/ijms231810950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 09/13/2022] [Accepted: 09/14/2022] [Indexed: 11/16/2022] Open
Abstract
Nitric oxide (NO) linked to glutamate receptors in the caudate and putamen (CPu) regulates neuroadaptation after drug exposure. Matrix-metalloproteinase (MMP), a Ca2+-dependent zinc-containing endopeptidase, increases mature brain-derived neurotrophic factor (BDNF) synthesis after drug exposure in the brain. The present study determined that NO synthesis linked to metabotropic glutamate receptor subtype 5 (mGluR5) stimulation after challenge exposure to nicotine activates MMP, which upregulates BDNF synthesis in the CPu. Subcutaneous injection of challenge nicotine (1.0 mg/kg) after repeated injections of nicotine (1.0 mg/kg/day) for 14 days and 7 days of nicotine withdrawal increased MMP2 activity and BDNF expression in the CPu of rats. These increases were prevented by the bilateral intra-CPu infusion of the mGluR5 antagonist, MPEP (0.1 nmol/side), the IP3 receptor antagonist, xestospongin C (0.004 nmol/side) or the neuronal nitric oxide synthase (nNOS) and NO inhibitor, Nω-propyl (0.1 nmol/side) prior to the challenge nicotine. Furthermore, bilateral intra-CPu infusion of the MMP2 inhibitor, OA-Hy (1 nmol/side) prevented the challenge nicotine-induced increase in the expression of BDNF. These findings suggest that elevation of NO synthesis linked to mGluR5 potentiates BDNF synthesis via activation of MMP2 after challenge exposure to nicotine in the CPu of rats.
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Impact of Inhibition of Glutamine and Alanine Transport on Cerebellar Glial and Neuronal Metabolism. Biomolecules 2022; 12:biom12091189. [PMID: 36139028 PMCID: PMC9496060 DOI: 10.3390/biom12091189] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Revised: 08/21/2022] [Accepted: 08/24/2022] [Indexed: 11/16/2022] Open
Abstract
The cerebellum, or “little brain”, is often overlooked in studies of brain metabolism in favour of the cortex. Despite this, anomalies in cerebellar amino acid homeostasis in a range of disorders have been reported. Amino acid homeostasis is central to metabolism, providing recycling of carbon backbones and ammonia between cell types. Here, we examined the role of cerebellar amino acid transporters in the cycling of glutamine and alanine in guinea pig cerebellar slices by inhibiting amino acid transporters and examining the resultant metabolism of [1-13C]d-glucose and [1,2-13C]acetate by NMR spectroscopy and LCMS. While the lack of specific inhibitors of each transporter makes interpretation difficult, by viewing results from experiments with multiple inhibitors we can draw inferences about the major cell types and transporters involved. In cerebellum, glutamine and alanine transfer is dominated by system A, blockade of which has maximum effect on metabolism, with contributions from System N. Inhibition of neural system A isoform SNAT1 by MeAIB resulted in greatly decreased metabolite pools and reduced net fluxes but showed little effect on fluxes from [1,2-13C]acetate unlike inhibition of SNAT3 and other glutamine transporters by histidine where net fluxes from [1,2-13C]acetate are reduced by ~50%. We interpret the data as further evidence of not one but several glutamate/glutamine exchange pools. The impact of amino acid transport inhibition demonstrates that the cerebellum has tightly coupled cells and that glutamate/glutamine, as well as alanine cycling, play a major role in that part of the brain.
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Adermark L, Lagström O, Loftén A, Licheri V, Havenäng A, Loi EA, Stomberg R, Söderpalm B, Domi A, Ericson M. Astrocytes modulate extracellular neurotransmitter levels and excitatory neurotransmission in dorsolateral striatum via dopamine D2 receptor signaling. Neuropsychopharmacology 2022; 47:1493-1502. [PMID: 34811469 PMCID: PMC9206030 DOI: 10.1038/s41386-021-01232-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Revised: 10/28/2021] [Accepted: 10/30/2021] [Indexed: 12/14/2022]
Abstract
Astrocytes provide structural and metabolic support of neuronal tissue, but may also be involved in shaping synaptic output. To further define the role of striatal astrocytes in modulating neurotransmission we performed in vivo microdialysis and ex vivo slice electrophysiology combined with metabolic, chemogenetic, and pharmacological approaches. Microdialysis recordings revealed that intrastriatal perfusion of the metabolic uncoupler fluorocitrate (FC) produced a robust increase in extracellular glutamate levels, with a parallel and progressive decline in glutamine. In addition, FC significantly increased the microdialysate concentrations of dopamine and taurine, but did not modulate the extracellular levels of glycine or serine. Despite the increase in glutamate levels, ex vivo electrophysiology demonstrated a reduced excitability of striatal neurons in response to FC. The decrease in evoked potentials was accompanied by an increased paired pulse ratio, and a reduced frequency of spontaneous excitatory postsynaptic currents, suggesting that FC depresses striatal output by reducing the probability of transmitter release. The effect by FC was mimicked by chemogenetic inhibition of astrocytes using Gi-coupled designer receptors exclusively activated by designer drugs (DREADDs) targeting GFAP, and by the glial glutamate transporter inhibitor TFB-TBOA. Both FC- and TFB-TBOA-mediated synaptic depression were inhibited in brain slices pre-treated with the dopamine D2 receptor antagonist sulpiride, but insensitive to agents acting on presynaptic glutamatergic autoreceptors, NMDA receptors, gap junction coupling, cannabinoid 1 receptors, µ-opioid receptors, P2 receptors or GABAA receptors. In conclusion, our data collectively support a role for astrocytes in modulating striatal neurotransmission and suggest that reduced transmission after astrocytic inhibition involves dopamine.
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Affiliation(s)
- Louise Adermark
- Addiction Biology Unit, Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden. .,Department of Pharmacology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
| | - Oona Lagström
- grid.8761.80000 0000 9919 9582Addiction Biology Unit, Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Anna Loftén
- grid.8761.80000 0000 9919 9582Addiction Biology Unit, Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden ,grid.1649.a000000009445082XBeroendekliniken, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Valentina Licheri
- grid.8761.80000 0000 9919 9582Addiction Biology Unit, Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Amy Havenäng
- grid.8761.80000 0000 9919 9582Addiction Biology Unit, Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Eleonora Anna Loi
- grid.8761.80000 0000 9919 9582Addiction Biology Unit, Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Rosita Stomberg
- grid.8761.80000 0000 9919 9582Addiction Biology Unit, Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Bo Söderpalm
- grid.8761.80000 0000 9919 9582Addiction Biology Unit, Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden ,grid.1649.a000000009445082XBeroendekliniken, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Ana Domi
- grid.8761.80000 0000 9919 9582Addiction Biology Unit, Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Mia Ericson
- grid.8761.80000 0000 9919 9582Addiction Biology Unit, Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
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Roy D, Puvvada M, Kapanaiah SKT, Patel AB. Enhanced Cortical Metabolic Activity in Females and Males of a Slow Progressing Mouse Model of Amyotrophic Lateral Sclerosis. Neurochem Res 2022; 47:1765-1777. [PMID: 35347633 DOI: 10.1007/s11064-022-03568-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 02/23/2022] [Accepted: 02/28/2022] [Indexed: 10/18/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder with selective degeneration of motor neurons in the central nervous system. The pathophysiology of ALS is not well understood. We have used 1H-[13C]-NMR spectroscopy together with an administration of [1,6-13C2]glucose and [2-13C]acetate in female and male SOD1G37R mice to assess neuronal and astroglial metabolic activity, respectively, in the central nervous system in ALS condition. The female (p = 0.0008) and male (p < 0.0001) SOD1G37R mice exhibited decreased forelimb strength when compared with wild-type mice. There was a reduction in N-acetylaspartylglutamate level, and elevation in myo-inositol in the spinal cord of female and male SOD1G37R mice. The transgenic male mice exhibited increased acetate oxidation in the spinal cord (p = 0.05) and cerebral cortex (p = 0.03), while females showed an increase in the spinal cord (p = 0.02) only. As acetate is transported and preferentially metabolized in the astrocytes, the finding of increased rate of acetate oxidation in the transgenic mice is suggestive of astrocytic involvement in the pathogenesis of ALS. The rates of glucose oxidation in glutamatergic (p = 0.0004) and GABAergic neurons (p = 0.0052) were increased in the cerebral cortex of male SOD1G37R mice when compared with the controls. The female mice showed an increase in glutamatergic (p = 0.039) neurometabolic activity only. The neurometabolic activity was unperturbed in the spinal cord of either sex. These data suggest differential changes in neurometabolic activity across the central nervous system in SOD1G37R mice.
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Affiliation(s)
- Dipak Roy
- NMR Microimaging and Spectroscopy, CSIR-Centre for Cellular and Molecular Biology, Habsiguda, Uppal Road, Hyderabad, 500007, India
| | - Madhuri Puvvada
- NMR Microimaging and Spectroscopy, CSIR-Centre for Cellular and Molecular Biology, Habsiguda, Uppal Road, Hyderabad, 500007, India
| | - Sampath K T Kapanaiah
- NMR Microimaging and Spectroscopy, CSIR-Centre for Cellular and Molecular Biology, Habsiguda, Uppal Road, Hyderabad, 500007, India
| | - Anant Bahadur Patel
- NMR Microimaging and Spectroscopy, CSIR-Centre for Cellular and Molecular Biology, Habsiguda, Uppal Road, Hyderabad, 500007, India. .,Academy of Scientific and Innovative Research, Ghaziabad, 201002, India.
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11
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Weis SN, Souza JMF, Hoppe JB, Firmino M, Auer M, Ataii NN, da Silva LA, Gaelzer MM, Klein CP, Mól AR, de Lima CMR, Souza DO, Salbego CG, Ricart CAO, Fontes W, de Sousa MV. In-depth quantitative proteomic characterization of organotypic hippocampal slice culture reveals sex-specific differences in biochemical pathways. Sci Rep 2021; 11:2560. [PMID: 33510253 PMCID: PMC7844295 DOI: 10.1038/s41598-021-82016-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Accepted: 12/21/2020] [Indexed: 12/19/2022] Open
Abstract
Sex differences in the brain of mammals range from neuroarchitecture through cognition to cellular metabolism. The hippocampus, a structure mostly associated with learning and memory, presents high vulnerability to neurodegeneration and aging. Therefore, we explored basal sex-related differences in the proteome of organotypic hippocampal slice culture, a major in vitro model for studying the cellular and molecular mechanisms related to neurodegenerative disorders. Results suggest a greater prevalence of astrocytic metabolism in females and significant neuronal metabolism in males. The preference for glucose use in glycolysis, pentose phosphate pathway and glycogen metabolism in females and high abundance of mitochondrial respiration subunits in males support this idea. An overall upregulation of lipid metabolism was observed in females. Upregulation of proteins responsible for neuronal glutamate and GABA synthesis, along with synaptic associated proteins, were observed in males. In general, the significant spectrum of pathways known to predominate in neurons or astrocytes, together with the well-known neuronal and glial markers observed, revealed sex-specific metabolic differences in the hippocampus. TEM qualitative analysis might indicate a greater presence of mitochondria at CA1 synapses in females. These findings are crucial to a better understanding of how sex chromosomes can influence the physiology of cultured hippocampal slices and allow us to gain insights into distinct responses of males and females on neurological diseases that present a sex-biased incidence.
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Affiliation(s)
- Simone Nardin Weis
- Laboratory of Protein Chemistry and Biochemistry, Department of Cell Biology, Institute of Biology, University of Brasília, Brasília, DF, 70910-900, Brazil.
| | - Jaques Miranda F Souza
- Laboratory of Protein Chemistry and Biochemistry, Department of Cell Biology, Institute of Biology, University of Brasília, Brasília, DF, 70910-900, Brazil
| | - Juliana Bender Hoppe
- Department of Biochemistry, Federal University of Rio Grande do Sul, Porto Alegre, 90035-003, Brazil
| | - Marina Firmino
- Laboratory of Protein Chemistry and Biochemistry, Department of Cell Biology, Institute of Biology, University of Brasília, Brasília, DF, 70910-900, Brazil
| | - Manfred Auer
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, MS Donner, Berkeley, CA, 94720, USA
| | - Nassim N Ataii
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, MS Donner, Berkeley, CA, 94720, USA
| | - Leonardo Assis da Silva
- Laboratory of Electron Microscopy, Department of Cell Biology, Institute of Biological Sciences, University of Brasília, Brasília, DF, 70910-900, Brazil
| | | | - Caroline Peres Klein
- Department of Biochemistry, Federal University of Rio Grande do Sul, Porto Alegre, 90035-003, Brazil
| | - Alan R Mól
- Laboratory of Protein Chemistry and Biochemistry, Department of Cell Biology, Institute of Biology, University of Brasília, Brasília, DF, 70910-900, Brazil
| | - Consuelo M R de Lima
- Laboratory of Protein Chemistry and Biochemistry, Department of Cell Biology, Institute of Biology, University of Brasília, Brasília, DF, 70910-900, Brazil
| | - Diogo Onofre Souza
- Department of Biochemistry, Federal University of Rio Grande do Sul, Porto Alegre, 90035-003, Brazil
| | - Christianne G Salbego
- Department of Biochemistry, Federal University of Rio Grande do Sul, Porto Alegre, 90035-003, Brazil
| | - Carlos André O Ricart
- Laboratory of Protein Chemistry and Biochemistry, Department of Cell Biology, Institute of Biology, University of Brasília, Brasília, DF, 70910-900, Brazil
| | - Wagner Fontes
- Laboratory of Protein Chemistry and Biochemistry, Department of Cell Biology, Institute of Biology, University of Brasília, Brasília, DF, 70910-900, Brazil
| | - Marcelo Valle de Sousa
- Laboratory of Protein Chemistry and Biochemistry, Department of Cell Biology, Institute of Biology, University of Brasília, Brasília, DF, 70910-900, Brazil
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12
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Popek M, Bobula B, Sowa J, Hess G, Frontczak-Baniewicz M, Albrecht J, Zielińska M. Physiology and Morphological Correlates of Excitatory Transmission are Preserved in Glutamine Transporter SN1-Depleted Mouse Frontal Cortex. Neuroscience 2020; 446:124-136. [DOI: 10.1016/j.neuroscience.2020.08.019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 07/16/2020] [Accepted: 08/14/2020] [Indexed: 01/22/2023]
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13
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Qureshi T, Bjørkmo M, Nordengen K, Gundersen V, Utheim TP, Watne LO, Storm-Mathisen J, Hassel B, Chaudhry FA. Slc38a1 Conveys Astroglia-Derived Glutamine into GABAergic Interneurons for Neurotransmitter GABA Synthesis. Cells 2020; 9:E1686. [PMID: 32668809 PMCID: PMC7407890 DOI: 10.3390/cells9071686] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 07/06/2020] [Accepted: 07/08/2020] [Indexed: 12/17/2022] Open
Abstract
GABA signaling is involved in a wide range of neuronal functions, such as synchronization of action potential firing, synaptic plasticity and neuronal development. Sustained GABA signaling requires efficient mechanisms for the replenishment of the neurotransmitter pool of GABA. The prevailing theory is that exocytotically released GABA may be transported into perisynaptic astroglia and converted to glutamine, which is then shuttled back to the neurons for resynthesis of GABA-i.e., the glutamate/GABA-glutamine (GGG) cycle. However, an unequivocal demonstration of astroglia-to-nerve terminal transport of glutamine and the contribution of astroglia-derived glutamine to neurotransmitter GABA synthesis is lacking. By genetic inactivation of the amino acid transporter Solute carrier 38 member a1 (Slc38a1)-which is enriched on parvalbumin+ GABAergic neurons-and by intraperitoneal injection of radiolabeled acetate (which is metabolized to glutamine in astroglial cells), we show that Slc38a1 mediates import of astroglia-derived glutamine into GABAergic neurons for synthesis of GABA. In brain slices, we demonstrate the role of Slc38a1 for the uptake of glutamine specifically into GABAergic nerve terminals for the synthesis of GABA depending on demand and glutamine supply. Thus, while leaving room for other pathways, our study demonstrates a key role of Slc38a1 for newly formed GABA, in harmony with the existence of a GGG cycle.
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Affiliation(s)
- Tayyaba Qureshi
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway; (T.Q.); (M.B.); (K.N.); (V.G.); (J.S.-M.)
| | - Mona Bjørkmo
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway; (T.Q.); (M.B.); (K.N.); (V.G.); (J.S.-M.)
| | - Kaja Nordengen
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway; (T.Q.); (M.B.); (K.N.); (V.G.); (J.S.-M.)
| | - Vidar Gundersen
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway; (T.Q.); (M.B.); (K.N.); (V.G.); (J.S.-M.)
| | - Tor Paaske Utheim
- Department of Plastic and Reconstructive Surgery, Oslo University Hospital, 0424 Oslo, Norway;
| | - Leiv Otto Watne
- Department of Geriatric Medicine, Oslo University Hospital, 0424 Oslo, Norway;
| | - Jon Storm-Mathisen
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway; (T.Q.); (M.B.); (K.N.); (V.G.); (J.S.-M.)
| | - Bjørnar Hassel
- Department of Neurohabilitation, Oslo University Hospital and University of Oslo, 0424 Oslo, Norway;
| | - Farrukh Abbas Chaudhry
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway; (T.Q.); (M.B.); (K.N.); (V.G.); (J.S.-M.)
- Department of Plastic and Reconstructive Surgery, Oslo University Hospital, 0424 Oslo, Norway;
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14
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Kumari S, Kumaran SS, Goyal V, Bose S, Jain S, Dwivedi SN, Srivastava AK, Jagannathan NR. Metabolomic analysis of serum using proton NMR in 6-OHDA experimental PD model and patients with PD. Neurochem Int 2020; 134:104670. [PMID: 31917997 DOI: 10.1016/j.neuint.2020.104670] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 12/30/2019] [Accepted: 01/04/2020] [Indexed: 12/12/2022]
Affiliation(s)
- Sadhana Kumari
- Department of NMR and MRI Facility, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India
| | - S Senthil Kumaran
- Department of NMR and MRI Facility, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India.
| | - Vinay Goyal
- Department of Neurology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India
| | - Samrat Bose
- Department of Physiology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India
| | - Suman Jain
- Department of Physiology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India
| | - Sada Nand Dwivedi
- Department of Biostatistics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India
| | - Achal Kumar Srivastava
- Department of Neurology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India
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15
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Ozgur O, Vugar Ali T, Iskender Samet D, Meside G, Lutfiye T, Servet Birgin I, Hakan AK. Pro-inflammatory cytokine and vascular adhesion molecule levels in manganese and lead-exposed workers. ACTA ACUST UNITED AC 2019. [DOI: 10.17352/2455-8591.000020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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16
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Velásquez E, Martins-de-Souza D, Velásquez I, Carneiro GRA, Schmitt A, Falkai P, Domont GB, Nogueira FCS. Quantitative Subcellular Proteomics of the Orbitofrontal Cortex of Schizophrenia Patients. J Proteome Res 2019; 18:4240-4253. [PMID: 31581776 DOI: 10.1021/acs.jproteome.9b00398] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Schizophrenia is a chronic disease characterized by the impairment of mental functions with a marked social dysfunction. A quantitative proteomic approach using iTRAQ labeling and SRM, applied to the characterization of mitochondria (MIT), crude nuclear fraction (NUC), and cytoplasm (CYT), can allow the observation of dynamic changes in cell compartments providing valuable insights concerning schizophrenia physiopathology. Mass spectrometry analyses of the orbitofrontal cortex from 12 schizophrenia patients and 8 healthy controls identified 655 protein groups in the MIT fraction, 1500 in NUC, and 1591 in CYT. We found 166 groups of proteins dysregulated among all enriched cellular fractions. Through the quantitative proteomic analysis, we detect as the main biological pathways those related to calcium and glutamate imbalance, cell signaling disruption of CREB activation, axon guidance, and proteins involved in the activation of NF-kB signaling along with the increase of complement protein C3. Based on our data analysis, we suggest the activation of NF-kB as a possible pathway that links the deregulation of glutamate, calcium, apoptosis, and the activation of the immune system in schizophrenia patients. All MS data are available in the ProteomeXchange Repository under the identifier PXD015356 and PXD014350.
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Affiliation(s)
- Erika Velásquez
- Proteomics Unit, Department of Biochemistry, Institute of Chemistry , Federal University of Rio de Janeiro , Rio de Janeiro 21941-909 , Brazil
| | - Daniel Martins-de-Souza
- Laboratory of Neuroproteomics, Department of Biochemistry, Institute of Biology , University of Campinas (UNICAMP) , Campinas 13083-970 , Brazil.,Experimental Medicine Research Cluster (EMRC) University of Campinas , Campinas 13083-887 , SP , Brazil.,Instituto Nacional de Biomarcadores em Neuropsiquiatria (INBION) , Conselho Nacional de Desenvolvimento Cientı́fico e Tecnológico (CNPq) , São Paulo , Brazil
| | | | - Gabriel Reis Alves Carneiro
- Laboratory of Proteomics, LADETEC, Institute of Chemistry , Federal University of Rio de Janeiro , Rio de Janeiro 21941-598 , Brazil
| | - Andrea Schmitt
- Department of Psychiatry and Psychotherapy , Ludwig Maximilian University of Munich (LMU) , 80539 Munich , Germany
| | - Peter Falkai
- Department of Psychiatry and Psychotherapy , Ludwig Maximilian University of Munich (LMU) , 80539 Munich , Germany
| | - Gilberto B Domont
- Proteomics Unit, Department of Biochemistry, Institute of Chemistry , Federal University of Rio de Janeiro , Rio de Janeiro 21941-909 , Brazil
| | - Fabio C S Nogueira
- Proteomics Unit, Department of Biochemistry, Institute of Chemistry , Federal University of Rio de Janeiro , Rio de Janeiro 21941-909 , Brazil.,Laboratory of Proteomics, LADETEC, Institute of Chemistry , Federal University of Rio de Janeiro , Rio de Janeiro 21941-598 , Brazil
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17
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Rothman DL, de Graaf RA, Hyder F, Mason GF, Behar KL, De Feyter HM. In vivo 13 C and 1 H-[ 13 C] MRS studies of neuroenergetics and neurotransmitter cycling, applications to neurological and psychiatric disease and brain cancer. NMR IN BIOMEDICINE 2019; 32:e4172. [PMID: 31478594 DOI: 10.1002/nbm.4172] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 04/30/2019] [Accepted: 05/07/2019] [Indexed: 06/10/2023]
Abstract
In the last 25 years 13 C MRS has been established as the only noninvasive method for measuring glutamate neurotransmission and cell specific neuroenergetics. Although technically and experimentally challenging 13 C MRS has already provided important new information on the relationship between neuroenergetics and neuronal function, the high energy cost of brain function in the resting state and the role of altered neuroenergetics and neurotransmitter cycling in disease. In this paper we review the metabolic and neurotransmitter pathways that can be measured by 13 C MRS and key findings on the linkage between neuroenergetics, neurotransmitter cycling, and brain function. Applications of 13 C MRS to neurological and psychiatric disease as well as brain cancer are reviewed. Recent technological developments that may help to overcome spatial resolution and brain coverage limitations of 13 C MRS are discussed.
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Affiliation(s)
- Douglas L Rothman
- Departments of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
- Department of Biomedical Engineering, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
- Departments of Radiology and Biomedical Imaging, and Biomedical Engineering, Magnetic Resonance Research Center, Yale University School of Medicine, 300 Cedar Street, P.O. Box 208043, New Haven, CT, USA
| | - Robin A de Graaf
- Departments of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
- Department of Biomedical Engineering, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Fahmeed Hyder
- Departments of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
- Department of Biomedical Engineering, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Graeme F Mason
- Departments of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Kevin L Behar
- Department of Psychiatry, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Henk M De Feyter
- Departments of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
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18
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Tefera TW, Borges K. Neuronal glucose metabolism is impaired while astrocytic TCA cycling is unaffected at symptomatic stages in the hSOD1 G93A mouse model of amyotrophic lateral sclerosis. J Cereb Blood Flow Metab 2019; 39:1710-1724. [PMID: 29553298 PMCID: PMC6727138 DOI: 10.1177/0271678x18764775] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Although alterations in energy metabolism are known in ALS, the specific mechanisms leading to energy deficit are not understood. We measured metabolite levels derived from injected [1-13C]glucose and [1,2-13C]acetate (i.p.) in cerebral cortex and spinal cord extracts of wild type and hSOD1G93A mice at onset and mid disease stages using high-pressure liquid chromatography, 1H and 13C nuclear magnetic resonance spectroscopy. Levels of spinal and cortical CNS total lactate, [3-13C]lactate, total alanine and [3-13C]alanine, but not cortical glucose and [1-13C]glucose, were reduced mostly at mid stage indicating impaired glycolysis. The [1-13C]glucose-derived [4-13C]glutamate, [4-13C]glutamine and [2-13C]GABA amounts were diminished at mid stage in cortex and both time points in spinal cord, suggesting decreased [3-13C]pyruvate entry into the TCA cycle. Lack of changes in [1,2-13C]acetate-derived [4,5-13C]glutamate, [4,5-13C]glutamine and [1,2-13C]GABA levels indicate unchanged astrocytic 13C-acetate metabolism. Reduced levels of leucine, isoleucine and valine in CNS suggest compensatory breakdown to refill TCA cycle intermediate levels. Unlabelled, [2-13C] and [4-13C]GABA concentrations were decreased in spinal cord indicating that impaired glucose metabolism contributes to hyperexcitability and supporting the use of treatments which increase GABA amounts. In conclusion, CNS glucose metabolism is compromised, while astrocytic TCA cycling appears to be normal in the hSOD1G93A mouse model at symptomatic disease stages.
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Affiliation(s)
- Tesfaye W Tefera
- Department of Pharmacology, School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia
| | - Karin Borges
- Department of Pharmacology, School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia
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19
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Brain metabolic and functional alterations in a liver-specific PTEN knockout mouse model. PLoS One 2018; 13:e0204043. [PMID: 30235271 PMCID: PMC6147462 DOI: 10.1371/journal.pone.0204043] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 08/31/2018] [Indexed: 01/11/2023] Open
Abstract
Insulin resistance-as observed in aging, diabetes, obesity, and other pathophysiological situations, affects brain function, for insulin signaling is responsible for neuronal glucose transport and control of energy homeostasis and is involved in the regulation of neuronal growth and synaptic plasticity. This study investigates brain metabolism and function in a liver-specific Phosphatase and Tensin Homologue (Pten) knockout mouse model (Liver-PtenKO), a negative regulator of insulin signaling. The Liver-PtenKO mouse model showed an increased flux of glucose into the liver-thus resulting in an overall hypoglycemic and hypoinsulinemic state-and significantly lower hepatic production of the ketone body beta-hydroxybutyrate (as compared with age-matched control mice). The Liver-PtenKO mice exhibited increased brain glucose uptake, improved rate of glycolysis and flux of metabolites in the TCA cycle, and improved synaptic plasticity in the hippocampus. Brain slices from both control- and Liver-PtenKO mice responded to the addition of insulin (in terms of pAKT/AKT levels), thereby neglecting an insulin resistance scenario. This study underscores the significance of insulin signaling in brain bioenergetics and function and helps recognize deficits in diseases associated with insulin resistance.
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20
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Parkin GM, Udawela M, Gibbons A, Dean B. Glutamate transporters, EAAT1 and EAAT2, are potentially important in the pathophysiology and treatment of schizophrenia and affective disorders. World J Psychiatry 2018; 8:51-63. [PMID: 29988908 PMCID: PMC6033743 DOI: 10.5498/wjp.v8.i2.51] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 05/15/2018] [Accepted: 06/09/2018] [Indexed: 02/05/2023] Open
Abstract
Glutamate is the predominant excitatory neurotransmitter in the human brain and it has been shown that prolonged activation of the glutamatergic system leads to nerve damage and cell death. Following release from the pre-synaptic neuron and synaptic transmission, glutamate is either taken up into the pre-synaptic neuron or neighbouring glia by transmembrane glutamate transporters. Excitatory amino acid transporter (EAAT) 1 and EAAT2 are Na+-dependant glutamate transporters expressed predominantly in glia cells of the central nervous system. As the most abundant glutamate transporters, their primary role is to modulate levels of glutamatergic excitability and prevent spill over of glutamate beyond the synapse. This role is facilitated through the binding and transportation of glutamate into astrocytes and microglia. The function of EAAT1 and EAAT2 is heavily regulated at the levels of gene expression, post-transcriptional splicing, glycosylation states and cell-surface trafficking of the protein. Both glutamatergic dysfunction and glial dysfunction have been proposed to be involved in psychiatric disorder. This review will present an overview of the roles that EAAT1 and EAAT2 play in modulating glutamatergic activity in the human brain, and mount an argument that these two transporters could be involved in the aetiologies of schizophrenia and affective disorders as well as represent potential drug targets for novel therapies for those disorders.
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Affiliation(s)
- Georgia M Parkin
- Molecular Psychiatry Laboratory, the Florey Institute of Neuroscience and Mental Health, Parkville VIC 3052, Australia
- CRC for Mental Health, Carlton VIC 3053, Australia
| | - Madhara Udawela
- Molecular Psychiatry Laboratory, the Florey Institute of Neuroscience and Mental Health, Parkville VIC 3052, Australia
- CRC for Mental Health, Carlton VIC 3053, Australia
| | - Andrew Gibbons
- Molecular Psychiatry Laboratory, the Florey Institute of Neuroscience and Mental Health, Parkville VIC 3052, Australia
| | - Brian Dean
- Molecular Psychiatry Laboratory, the Florey Institute of Neuroscience and Mental Health, Parkville VIC 3052, Australia
- CRC for Mental Health, Carlton VIC 3053, Australia
- Research Centre for Mental Health, the Faculty of Health, Arts and Design, Swinburne University, Hawthorne VIC 3122, Australia
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21
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Serum metabolomics study in a group of Parkinson's disease patients from northern India. Clin Chim Acta 2018; 480:214-219. [DOI: 10.1016/j.cca.2018.02.022] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 02/12/2018] [Accepted: 02/19/2018] [Indexed: 12/14/2022]
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22
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Gallegos CE, Baier CJ, Bartos M, Bras C, Domínguez S, Mónaco N, Gumilar F, Giménez MS, Minetti A. Perinatal Glyphosate-Based Herbicide Exposure in Rats Alters Brain Antioxidant Status, Glutamate and Acetylcholine Metabolism and Affects Recognition Memory. Neurotox Res 2018; 34:363-374. [PMID: 29611151 DOI: 10.1007/s12640-018-9894-2] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 03/08/2018] [Accepted: 03/21/2018] [Indexed: 01/18/2023]
Abstract
Glyphosate-based herbicides (Gly-BHs) lead the world pesticide market. Although are frequently promoted as safe and of low toxicity, several investigations question its innocuousness. Previously, we described that oral exposure of rats to a Gly-BH during pregnancy and lactation decreased locomotor activity and anxiety in the offspring. The aim of the present study was to evaluate the mechanisms of neurotoxicity of this herbicide. Pregnant Wistar rats were supplied orally with 0.2 and 0.4% of Gly-BH (corresponding to 0.65 and 1.30 g/l of pure Gly, respectively) from gestational day (GD) 0, until weaning (postnatal day, PND, 21). Oxidative stress markers were determined in whole brain homogenates of PND90 offspring. The activity of acetylcholinesterase (AChE), transaminases, and alkaline phosphatase (AP) were assessed in prefrontal cortex (PFC), striatum, and hippocampus. Recognition memory was evaluated by the novel object recognition test. Brain antioxidant status was altered in Gly-BH-exposed rats. Moreover, AChE and transaminases activities were decreased and AP activity was increased in PFC, striatum and hippocampus by Gly-BH treatment. In addition, the recognition memory after 24 h was impaired in adult offspring perinatally exposed to Gly-BH. The present study reveals that exposure to a Gly-BH during early stages of rat development affects brain oxidative stress markers as well as the activity of enzymes involved in the glutamatergic and cholinergic systems. These alterations could contribute to the neurobehavioral variations reported previously by us, and to the impairment in recognition memory described in the present work.
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Affiliation(s)
- Cristina Eugenia Gallegos
- Laboratorio de Toxicología, Instituto de Ciencias Biológicas y Biomédicas del Sur (INBIOSUR), Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur (UNS)-CONICET, San Juan 670, 8000, Bahía Blanca, Buenos Aires, Argentina.
| | - Carlos Javier Baier
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB), Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur (UNS)-CONICET, Bahía Blanca, Argentina
| | - Mariana Bartos
- Laboratorio de Toxicología, Instituto de Ciencias Biológicas y Biomédicas del Sur (INBIOSUR), Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur (UNS)-CONICET, San Juan 670, 8000, Bahía Blanca, Buenos Aires, Argentina
| | - Cristina Bras
- Laboratorio de Toxicología, Instituto de Ciencias Biológicas y Biomédicas del Sur (INBIOSUR), Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur (UNS)-CONICET, San Juan 670, 8000, Bahía Blanca, Buenos Aires, Argentina
| | - Sergio Domínguez
- Laboratorio de Toxicología, Instituto de Ciencias Biológicas y Biomédicas del Sur (INBIOSUR), Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur (UNS)-CONICET, San Juan 670, 8000, Bahía Blanca, Buenos Aires, Argentina
| | - Nina Mónaco
- Laboratorio de Toxicología, Instituto de Ciencias Biológicas y Biomédicas del Sur (INBIOSUR), Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur (UNS)-CONICET, San Juan 670, 8000, Bahía Blanca, Buenos Aires, Argentina
| | - Fernanda Gumilar
- Laboratorio de Toxicología, Instituto de Ciencias Biológicas y Biomédicas del Sur (INBIOSUR), Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur (UNS)-CONICET, San Juan 670, 8000, Bahía Blanca, Buenos Aires, Argentina
| | - María Sofía Giménez
- Departamento de Bioquímica y Ciencias Biológicas, Facultad de Química, Bioquímica y Farmacia, Universidad Nacional de San Luis, IMIBIO-SL, CONICET, San Luis, Argentina
| | - Alejandra Minetti
- Laboratorio de Toxicología, Instituto de Ciencias Biológicas y Biomédicas del Sur (INBIOSUR), Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur (UNS)-CONICET, San Juan 670, 8000, Bahía Blanca, Buenos Aires, Argentina
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Axon-terminals expressing EAAT2 (GLT-1; Slc1a2) are common in the forebrain and not limited to the hippocampus. Neurochem Int 2018. [PMID: 29530756 DOI: 10.1016/j.neuint.2018.03.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The excitatory amino acid transporter type 2 (EAAT2) represents the major mechanism for removal of extracellular glutamate. In the hippocampus, there is some EAAT2 in axon-terminals, whereas most of the protein is found in astroglia. The functional importance of the neuronal EAAT2 is unknown, and it is debated whether EAAT2-expressing nerve terminals are present in other parts of the brain. Here we selectively deleted the EAAT2 gene in neurons (by crossing EAAT2-flox mice with synapsin 1-Cre mice in the C57B6 background). To reduce interference from astroglial EAAT2, we measured glutamate accumulation in crude tissue homogenates. EAAT2 proteins levels were measured by immunoblotting. Although synapsin 1-Cre mediated gene deletion only reduced the forebrain tissue content of EAAT2 protein to 95.5 ± 3.4% of wild-type (littermate) controls, the glutamate accumulation in homogenates of neocortex, hippocampus, striatum and thalamus were nevertheless diminished to, respectively, 54 ± 4, 46 ± 3, 46 ± 2 and 65 ± 7% of controls (average ± SEM, n = 3 pairs of littermates). GABA uptake was unaffected. After injection of U-13C-glucose, lack of neuronal EAAT2 resulted in higher 13C-labeling of glutamine and GABA in the hippocampus suggesting that neuronal EAAT2 is partly short-circuiting the glutamate-glutamine cycle in wild-type mice. Crossing synapsin 1-Cre mice with Ai9 reporter mice revealed that Cre-mediated excision occurred efficiently in hippocampus CA3, but less efficiently in other regions and hardly at all in the cerebellum. Conclusions: (1) EAAT2 is expressed in nerve terminals in multiple brain regions. (2) The uptake catalyzed by neuronal EAAT2 plays a role in glutamate metabolism, at least in the hippocampus. (3) Synapsin 1-Cre does not delete floxed genes in all neurons, and the contribution of neuronal EAAT2 is therefore likely to be larger than revealed in the present study.
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Hohnholt MC, Blumrich EM, Waagepetersen HS, Dringen R. The antidiabetic drug metformin decreases mitochondrial respiration and tricarboxylic acid cycle activity in cultured primary rat astrocytes. J Neurosci Res 2017; 95:2307-2320. [PMID: 28316081 DOI: 10.1002/jnr.24050] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 02/20/2017] [Accepted: 02/21/2017] [Indexed: 12/18/2022]
Abstract
Metformin is an antidiabetic drug that is used daily by millions of patients worldwide. Metformin is able to cross the blood-brain barrier and has recently been shown to increase glucose consumption and lactate release in cultured astrocytes. However, potential effects of metformin on mitochondrial tricarboxylic acid (TCA) cycle metabolism in astrocytes are unknown. We investigated this by mapping 13 C labeling in TCA cycle intermediates and corresponding amino acids after incubation of primary rat astrocytes with [U-13 C]glucose. The presence of metformin did not compromise the viability of cultured astrocytes during 4 hr of incubation, but almost doubled cellular glucose consumption and lactate release. Compared with control cells, the presence of metformin dramatically lowered the molecular 13 C carbon labeling (MCL) of the cellular TCA cycle intermediates citrate, α-ketoglutarate, succinate, fumarate, and malate, as well as the MCL of the TCA cycle intermediate-derived amino acids glutamate, glutamine, and aspartate. In addition to the total molecular 13 C labeling, analysis of the individual isotopomers of TCA cycle intermediates confirmed a severe decline in labeling and a significant lowering in TCA cycling ratio in metformin-treated astrocytes. Finally, the oxygen consumption of mitochondria isolated from metformin-treated astrocytes was drastically reduced in the presence of complex I substrates, but not of complex II substrates. These data demonstrate that exposure to metformin strongly impairs complex I-mediated mitochondrial respiration in astrocytes, which is likely to cause the observed decrease in labeling of mitochondrial TCA cycle intermediates and the stimulation of glycolytic lactate production. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Michaela C Hohnholt
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark
| | - Eva-Maria Blumrich
- Centre for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, Bremen, Germany.,Centre for Environmental Research and Sustainable Technology, Bremen, Germany
| | - Helle S Waagepetersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark
| | - Ralf Dringen
- Centre for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, Bremen, Germany.,Centre for Environmental Research and Sustainable Technology, Bremen, Germany
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25
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Hemodynamic Changes Associated with Interictal Spikes Induced by Acute Models of Focal Epilepsy in Rats: A Simultaneous Electrocorticography and Near-Infrared Spectroscopy Study. Brain Topogr 2017; 30:390-407. [DOI: 10.1007/s10548-016-0541-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 12/15/2016] [Indexed: 02/07/2023]
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26
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Westergaard N, Waagepetersen HS, Belhage B, Schousboe A. Citrate, a Ubiquitous Key Metabolite with Regulatory Function in the CNS. Neurochem Res 2017; 42:1583-1588. [DOI: 10.1007/s11064-016-2159-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Revised: 12/16/2016] [Accepted: 12/19/2016] [Indexed: 11/30/2022]
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27
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Pavlin T, Nagelhus EA, Brekken C, Eyjolfsson EM, Thoren A, Haraldseth O, Sonnewald U, Ottersen OP, Håberg AK. Loss or Mislocalization of Aquaporin-4 Affects Diffusion Properties and Intermediary Metabolism in Gray Matter of Mice. Neurochem Res 2016; 42:77-91. [DOI: 10.1007/s11064-016-2139-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Revised: 12/02/2016] [Accepted: 12/08/2016] [Indexed: 11/27/2022]
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Mechanisms of Excessive Extracellular Glutamate Accumulation in Temporal Lobe Epilepsy. Neurochem Res 2016; 42:1724-1734. [DOI: 10.1007/s11064-016-2105-8] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 11/08/2016] [Accepted: 11/09/2016] [Indexed: 12/17/2022]
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29
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Wolosker H, Balu DT, Coyle JT. The Rise and Fall of the d-Serine-Mediated Gliotransmission Hypothesis. Trends Neurosci 2016; 39:712-721. [PMID: 27742076 DOI: 10.1016/j.tins.2016.09.007] [Citation(s) in RCA: 132] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Revised: 09/19/2016] [Accepted: 09/20/2016] [Indexed: 01/26/2023]
Abstract
d-Serine modulates N-methyl d-aspartate receptors (NMDARs) and regulates synaptic plasticity, neurodevelopment, and learning and memory. However, the primary site of d-serine synthesis and release remains controversial, with some arguing that it is a gliotransmitter and others defining it as a neuronal cotransmitter. Results from several laboratories using different strategies now show that the biosynthetic enzyme of d-serine, serine racemase (SR), is expressed almost entirely by neurons, with few astrocytes appearing to contain d-serine. Cell-selective suppression of SR expression demonstrates that neuronal, rather than astrocytic d-serine, modulates synaptic plasticity. Here, we propose an alternative conceptualization whereby astrocytes affect d-serine levels by synthesizing l-serine that shuttles to neurons to fuel the neuronal synthesis of d-serine.
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Affiliation(s)
- Herman Wolosker
- Department of Biochemistry, Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa 31096, Israel.
| | - Darrick T Balu
- Department of Psychiatry, Harvard Medical School, Boston, MA, USA; Translational Psychiatry Laboratory, McLean Hospital, Belmont, MA 02478, USA.
| | - Joseph T Coyle
- Department of Psychiatry, Harvard Medical School, Boston, MA, USA; Laboratory of Psychiatric and Molecular Neuroscience, McLean Hospital, Belmont, MA 02478, USA.
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30
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Glia plasma membrane transporters: Key players in glutamatergic neurotransmission. Neurochem Int 2016; 98:46-55. [DOI: 10.1016/j.neuint.2016.04.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 03/07/2016] [Accepted: 04/06/2016] [Indexed: 12/27/2022]
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Okada M, Yanamoto K, Kagawa T, Yoshino K, Hosoi R, Abe K, Zhang MR, Inoue O. Kinetic study of benzyl [1-14C]acetate as a potential probe for astrocytic energy metabolism in the rat brain: Comparison with benzyl [2-14C]acetate. J Cereb Blood Flow Metab 2016; 36:442-50. [PMID: 26661153 PMCID: PMC4759666 DOI: 10.1177/0271678x15606144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Accepted: 07/28/2015] [Indexed: 11/15/2022]
Abstract
Brain uptake of [(14)C]acetate has been reported to be a useful marker of astrocytic energy metabolism. In addition to uptake values, the rate of radiolabeled acetate washout from the brain appears to reflect CO2 exhaustion and oxygen consumption in astrocytes. We measured the time-radioactivity curves of benzyl [1-(14)C]acetate ([1-(14)C]BA), a lipophilic probe of [1-(14)C]acetate, and compared it with that of benzyl [2-(14)C]acetate ([2-(14)C]BA) in rat brains. The highest brain uptake was observed immediately after injecting either [1-(14)C]BA or [2-(14)C]BA, and both subsequently disappeared from the brain in a single-exponential manner. Estimated [1-(14)C]BA washout rates in the cerebral cortex and cerebellum were higher than those of [2-(14)C]BA. These results suggested that [1-(14)C]BA could be a useful probe for estimating the astrocytic oxidative metabolism. The [1-(14)C]BA washout rate in the cerebral cortex of immature rats was lower than that of mature rats. An autoradiographic study showed that the washout rates of [1-(14)C]BA from the rat brains of a lithium-pilocarpine-induced status epilepticus model were not significantly different from the values in control rat brains except for the medial septal nucleus. These results implied that the enhancement of amino acid turnover rate rather than astrocytic oxidative metabolism was increased in status epilepticus.
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Affiliation(s)
- Maki Okada
- Molecular Probe Program, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba, Japan
| | - Kazuhiko Yanamoto
- Division of Health Sciences, Osaka University Graduate School of Medicine, Suita, Japan
| | - Tomohiko Kagawa
- Division of Health Sciences, Osaka University Graduate School of Medicine, Suita, Japan
| | - Keiko Yoshino
- Division of Health Sciences, Osaka University Graduate School of Medicine, Suita, Japan
| | - Rie Hosoi
- Division of Health Sciences, Osaka University Graduate School of Medicine, Suita, Japan
| | - Kohji Abe
- Department of Molecular Imaging in Medicine, Osaka University Graduate School of Medicine, Suita, Japan Department of Drug Metabolism & Pharmacokinetics, Research Laboratory for Development, Shionogi & Co., Ltd., Toyonaka, Japan
| | - Ming-Rong Zhang
- Molecular Probe Program, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba, Japan
| | - Osamu Inoue
- Division of Health Sciences, Osaka University Graduate School of Medicine, Suita, Japan
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MacEachern SJ, Patel BA, Keenan CM, Dicay M, Chapman K, McCafferty DM, Savidge TC, Beck PL, MacNaughton WK, Sharkey KA. Inhibiting Inducible Nitric Oxide Synthase in Enteric Glia Restores Electrogenic Ion Transport in Mice With Colitis. Gastroenterology 2015; 149:445-55.e3. [PMID: 25865048 PMCID: PMC4516675 DOI: 10.1053/j.gastro.2015.04.007] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Revised: 03/06/2015] [Accepted: 04/06/2015] [Indexed: 02/06/2023]
Abstract
BACKGROUND & AIMS Disturbances in the control of ion transport lead to epithelial barrier dysfunction in patients with colitis. Enteric glia regulate intestinal barrier function and colonic ion transport. However, it is not clear whether enteric glia are involved in epithelial hyporesponsiveness. We investigated enteric glial regulation of ion transport in mice with trinitrobenzene sulfonic acid- or dextran sodium sulfate-induced colitis and in Il10(-/-) mice. METHODS Electrically evoked ion transport was measured in full-thickness segments of colon from CD1 and Il10(-/-) mice with or without colitis in Ussing chambers. Nitric oxide (NO) production was assessed using amperometry. Bacterial translocation was investigated in the liver, spleen, and blood of mice. RESULTS Electrical stimulation of the colon evoked a tetrodotoxin-sensitive chloride secretion. In mice with colitis, ion transport almost completely disappeared. Inhibiting inducible NO synthase (NOS2), but not neuronal NOS (NOS1), partially restored the evoked secretory response. Blocking glial function with fluoroacetate, which is not a NOS2 inhibitor, also partially restored ion transport. Combined NOS2 inhibition and fluoroacetate administration fully restored secretion. Epithelial responsiveness to vasoactive intestinal peptide was increased after enteric glial function was blocked in mice with colitis. In colons of mice without colitis, NO was produced in the myenteric plexus almost completely via NOS1. NO production was increased in mice with colitis, compared with mice without colitis; a substantial proportion of NOS2 was blocked by fluoroacetate administration. Inhibition of enteric glial function in vivo reduced the severity of trinitrobenzene sulfonic acid-induced colitis and associated bacterial translocation. CONCLUSIONS Increased production of NOS2 in enteric glia contributes to the dysregulation of intestinal ion transport in mice with colitis. Blocking enteric glial function in these mice restores epithelial barrier function and reduces bacterial translocation.
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Affiliation(s)
- Sarah J. MacEachern
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Snyder Institute for Chronic Diseases, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Bhavik A. Patel
- School of Pharmacy and Biomolecular Sciences, University of Brighton, Huxley Building, Brighton, UK
| | - Catherine M. Keenan
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Snyder Institute for Chronic Diseases, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Michael Dicay
- Snyder Institute for Chronic Diseases, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Kevin Chapman
- Snyder Institute for Chronic Diseases, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Donna-Marie McCafferty
- Snyder Institute for Chronic Diseases, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Tor C. Savidge
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX, USA
| | - Paul L. Beck
- Snyder Institute for Chronic Diseases, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Department of Medicine, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Wallace K. MacNaughton
- Snyder Institute for Chronic Diseases, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Keith A. Sharkey
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Snyder Institute for Chronic Diseases, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
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Dervola KSN, Johansen EB, Walaas SI, Fonnum F. Gender-dependent and genotype-sensitive monoaminergic changes induced by polychlorinated biphenyl 153 in the rat brain. Neurotoxicology 2015. [PMID: 26215117 DOI: 10.1016/j.neuro.2015.07.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Polychlorinated biphenyls (PCBs) are present as ortho- and non-ortho-substituted PCBs, with most of the ortho-substituted congeners being neurotoxic. The present study examined effects of the ortho-substituted PCB 153 on dopamine, serotonin and amino acid neurotransmitters in the neostriatum of both male and female Wistar Kyoto (WKY) and spontaneously hypertensive rat (SHR) genotypes. PCB 153 exposure at p8, p14 and p20 had no effects on levels of these transmitters when examined at p55, but led to increased levels of both homovanillic acid and 5-hydroxyindoleacetic acid, the degradation products of dopamine and serotonin, respectively, in all groups except the female SHR. Immunoblotting showed that PCB exposure induced gender-specific decreases in dopaminergic synaptic proteins. These included a novel finding of decreased levels of the dopamine D5 receptor in both genders and genotypes, whereas male-specific changes included decreases in the postsynaptic density (PSD)-95 protein in the WKY and SHRs and a decrease in the presynaptic dopamine transporter in both the WKY and, less clearly in the male SHR. A female-specific tendency of increased vesicular monoamine transporter-2 was observed in the SHRs after PCB exposure. No changes were seen in tyrosine hydroxylase, the cytoskeletal neurotubulin or the plasma membrane marker Na(+)/K(+)-ATPase in any strain. Hence, PCB-exposure led to increases in monoamine transmitter turnover in both male and female animals, whereas decreases in both pre- and postsynaptic dopaminergic proteins were predominantly seen in male animals. PCB 153 may therefore induce neostriatal toxicity through both presynaptic and postsynaptic mechanisms in both genotypes and genders, including effects on the aspiny interneurons, which employ the D5 receptor to mediate dopamine effects on interneurons in the basal ganglia.
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Affiliation(s)
- Kine S N Dervola
- Department of Biochemistry, Division of Molecular Medicine, Institute of Basic Medical Science, University of Oslo, Norway
| | - Espen B Johansen
- Oslo and Akershus University College of Applied Sciences, Oslo, Norway
| | - S Ivar Walaas
- Department of Biochemistry, Division of Molecular Medicine, Institute of Basic Medical Science, University of Oslo, Norway.
| | - Frode Fonnum
- Department of Biochemistry, Division of Molecular Medicine, Institute of Basic Medical Science, University of Oslo, Norway
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Abstract
The understanding of manganese (Mn) biology, in particular its cellular regulation and role in neurological disease, is an area of expanding interest. Mn is an essential micronutrient that is required for the activity of a diverse set of enzymatic proteins (e.g., arginase and glutamine synthase). Although necessary for life, Mn is toxic in excess. Thus, maintaining appropriate levels of intracellular Mn is critical. Unlike other essential metals, cell-level homeostatic mechanisms of Mn have not been identified. In this review, we discuss common forms of Mn exposure, absorption, and transport via regulated uptake/exchange at the gut and blood-brain barrier and via biliary excretion. We present the current understanding of cellular uptake and efflux as well as subcellular storage and transport of Mn. In addition, we highlight the Mn-dependent and Mn-responsive pathways implicated in the growing evidence of its role in Parkinson's disease and Huntington's disease. We conclude with suggestions for future focuses of Mn health-related research.
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Affiliation(s)
- Kyle J Horning
- Department of Neurology, Vanderbilt University, Nashville, Tennessee 37232; , ,
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The Glutamine–Glutamate/GABA Cycle: Function, Regional Differences in Glutamate and GABA Production and Effects of Interference with GABA Metabolism. Neurochem Res 2014; 40:402-9. [DOI: 10.1007/s11064-014-1473-1] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Revised: 10/30/2014] [Accepted: 10/31/2014] [Indexed: 10/24/2022]
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Marin-Valencia I, Hooshyar MA, Pichumani K, Sherry AD, Malloy CR. The ratio of acetate-to-glucose oxidation in astrocytes from a single 13C NMR spectrum of cerebral cortex. J Neurochem 2014; 132:99-109. [PMID: 25231025 DOI: 10.1111/jnc.12948] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Revised: 08/13/2014] [Accepted: 09/15/2014] [Indexed: 11/30/2022]
Abstract
The (13) C-labeling patterns in glutamate and glutamine from brain tissue are quite different after infusion of a mixture of (13) C-enriched glucose and acetate. Two processes contribute to this observation, oxidation of acetate by astrocytes but not neurons, and preferential incorporation of α-ketoglutarate into glutamate in neurons, and incorporation of α-ketoglutarate into glutamine in astrocytes. The acetate:glucose ratio, introduced previously for analysis of a single (13) C NMR spectrum, provides a useful index of acetate and glucose oxidation in the brain tissue. However, quantitation of relative substrate oxidation at the cell compartment level has not been reported. A simple mathematical method is presented to quantify the ratio of acetate-to-glucose oxidation in astrocytes, based on the standard assumption that neurons do not oxidize acetate. Mice were infused with [1,2-(13) C]acetate and [1,6-(13) C]glucose, and proton decoupled (13) C NMR spectra of cortex extracts were acquired. A fit of those spectra to the model indicated that (13) C-labeled acetate and glucose contributed approximately equally to acetyl-CoA (0.96) in astrocytes. As this method relies on a single (13) C NMR spectrum, it can be readily applied to multiple physiologic and pathologic conditions. Differences in (13) C labeling of brain glutamate and glutamine have been attributed to metabolic compartmentation. The acetate:glucose ratio, introduced for description of a (13) C NMR (nuclear magnetic resonance) spectrum, is an index of glucose and acetate oxidation in brain tissue. A simple mathematical method is presented to quantify the ratio of acetate-to-glucose oxidation in astrocytes from a single NMR spectrum. As kinetic analysis is not required, the method is readily applicable to analysis of tissue extracts. α-KG = alpha-ketoglutarate; CAC = citric acid cycle; GLN = glutamine; GLU = glutamate.
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Affiliation(s)
- Isaac Marin-Valencia
- Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, USA; Department of Pediatrics, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, USA
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Zhou L, Wang H, Luo J, Xiong K, Zeng L, Chen D, Huang J. Regulatory effects of inhibiting the activation of glial cells on retinal synaptic plasticity. Neural Regen Res 2014; 9:385-93. [PMID: 25206825 PMCID: PMC4146193 DOI: 10.4103/1673-5374.128240] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/04/2014] [Indexed: 01/09/2023] Open
Abstract
Various retinal injuries induced by ocular hypertension have been shown to induce plastic changes in retinal synapses, but the potential regulatory mechanism of synaptic plasticity after retinal injury was still unclear. A rat model of acute ocular hypertension was established by injecting saline intravitreally for an hour, and elevating the intraocular pressure to 14.63 kPa (110 mmHg). Western blot assay and immunofluorescence results showed that synaptophysin expression had a distinct spatiotemporal change that increased in the inner plexiform layer within 1 day and spread across the outer plexiform layer after 3 days. Glial fibrillary acidic protein expression in retinae was greatly increased after 3 days, and reached a peak at 7 days, which was also consistent with the peak time of synaptophysin expression in the outer plexiform layer following the increased intraocular pressure. Fluorocitrate, a glial metabolic inhibitor, was intravitreally injected to inhibit glial cell activation following high intraocular pressure. This significantly inhibited the enhanced glial fibrillary acidic protein expression induced by high intraocular pressure injury. Synaptophysin expression also decreased in the inner plexiform layer within a day and the widened distribution in the outer plexiform layer had disappeared by 3 days. The results suggested that retinal glial cell activation might play an important role in the process of retinal synaptic plasticity induced by acute high intraocular pressure through affecting the expression and distribution of synaptic functional proteins, such as synaptophysin.
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Affiliation(s)
- Lihong Zhou
- Department of Human Anatomy and Neurobiology, School of Basic Medical Science, Central South University, Changsha, Hunan Province, China
| | - Hui Wang
- Department of Human Anatomy and Neurobiology, School of Basic Medical Science, Central South University, Changsha, Hunan Province, China
| | - Jia Luo
- Department of Human Anatomy and Neurobiology, School of Basic Medical Science, Central South University, Changsha, Hunan Province, China
| | - Kun Xiong
- Department of Human Anatomy and Neurobiology, School of Basic Medical Science, Central South University, Changsha, Hunan Province, China
| | - Leping Zeng
- Department of Human Anatomy and Neurobiology, School of Basic Medical Science, Central South University, Changsha, Hunan Province, China
| | - Dan Chen
- Department of Human Anatomy and Neurobiology, School of Basic Medical Science, Central South University, Changsha, Hunan Province, China
| | - Jufang Huang
- Department of Human Anatomy and Neurobiology, School of Basic Medical Science, Central South University, Changsha, Hunan Province, China
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Viluksela M, Heikkinen P, van der Ven LTM, Rendel F, Roos R, Esteban J, Korkalainen M, Lensu S, Miettinen HM, Savolainen K, Sankari S, Lilienthal H, Adamsson A, Toppari J, Herlin M, Finnilä M, Tuukkanen J, Leslie HA, Hamers T, Hamscher G, Al-Anati L, Stenius U, Dervola KS, Bogen IL, Fonnum F, Andersson PL, Schrenk D, Halldin K, Håkansson H. Toxicological profile of ultrapure 2,2',3,4,4',5,5'-heptachlorbiphenyl (PCB 180) in adult rats. PLoS One 2014; 9:e104639. [PMID: 25137063 PMCID: PMC4138103 DOI: 10.1371/journal.pone.0104639] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Accepted: 07/10/2014] [Indexed: 11/19/2022] Open
Abstract
PCB 180 is a persistent non-dioxin-like polychlorinated biphenyl (NDL-PCB) abundantly present in food and the environment. Risk characterization of NDL-PCBs is confounded by the presence of highly potent dioxin-like impurities. We used ultrapure PCB 180 to characterize its toxicity profile in a 28-day repeat dose toxicity study in young adult rats extended to cover endocrine and behavioral effects. Using a loading dose/maintenance dose regimen, groups of 5 males and 5 females were given total doses of 0, 3, 10, 30, 100, 300, 1000 or 1700 mg PCB 180/kg body weight by gavage. Dose-responses were analyzed using benchmark dose modeling based on dose and adipose tissue PCB concentrations. Body weight gain was retarded at 1700 mg/kg during loading dosing, but recovered thereafter. The most sensitive endpoint of toxicity that was used for risk characterization was altered open field behavior in females; i.e. increased activity and distance moved in the inner zone of an open field suggesting altered emotional responses to unfamiliar environment and impaired behavioral inhibition. Other dose-dependent changes included decreased serum thyroid hormones with associated histopathological changes, altered tissue retinoid levels, decreased hematocrit and hemoglobin, decreased follicle stimulating hormone and luteinizing hormone levels in males and increased expression of DNA damage markers in liver of females. Dose-dependent hypertrophy of zona fasciculata cells was observed in adrenals suggesting activation of cortex. There were gender differences in sensitivity and toxicity profiles were partly different in males and females. PCB 180 adipose tissue concentrations were clearly above the general human population levels, but close to the levels in highly exposed populations. The results demonstrate a distinct toxicological profile of PCB 180 with lack of dioxin-like properties required for assignment of WHO toxic equivalency factor. However, PCB 180 shares several toxicological targets with dioxin-like compounds emphasizing the potential for interactions.
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Affiliation(s)
- Matti Viluksela
- Department of Environmental Health, National Institute for Health and Welfare, Kuopio, Finland
- Department of Environmental Science, University of Eastern Finland, Kuopio, Finland
- * E-mail:
| | - Päivi Heikkinen
- Department of Environmental Health, National Institute for Health and Welfare, Kuopio, Finland
| | - Leo T. M. van der Ven
- Centre for Health Protection, National Institute for Public Health and the Environment, Bilthoven, The Netherlands
| | - Filip Rendel
- Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Robert Roos
- Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Javier Esteban
- Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
- Instituto de Bioingeniería, Universidad Miguel Hernández de Elche, Elche (Alicante), Spain
| | - Merja Korkalainen
- Department of Environmental Health, National Institute for Health and Welfare, Kuopio, Finland
| | - Sanna Lensu
- Department of Environmental Health, National Institute for Health and Welfare, Kuopio, Finland
- Department of Biology of Physical Activity, University of Jyväskylä, Jyväskylä, Finland
| | - Hanna M. Miettinen
- Department of Environmental Health, National Institute for Health and Welfare, Kuopio, Finland
| | | | - Satu Sankari
- Department of Equine and Small Animal Medicine, University of Helsinki, Helsinki, Finland
| | - Hellmuth Lilienthal
- Center of Toxicology, IPA – Institute for Prevention and Occupational Medicine, German Social Accident Insurance, Ruhr University of Bochum, Bochum, Germany
| | - Annika Adamsson
- Department of Physiology, University of Turku, Turku, Finland
| | - Jorma Toppari
- Department of Physiology, University of Turku, Turku, Finland
- Department of Paediatrics, University of Turku, Turku, Finland
| | - Maria Herlin
- Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Mikko Finnilä
- Department of Anatomy and Cell Biology, University of Oulu, Oulu, Finland
| | - Juha Tuukkanen
- Department of Anatomy and Cell Biology, University of Oulu, Oulu, Finland
| | - Heather A. Leslie
- Institute for Environmental Studies, VU University Amsterdam, Amsterdam, The Netherlands
| | - Timo Hamers
- Institute for Environmental Studies, VU University Amsterdam, Amsterdam, The Netherlands
| | - Gerd Hamscher
- Institute of Food Chemistry and Food Biotechnology, Justus-Liebig University, Giessen, Germany
| | - Lauy Al-Anati
- Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Ulla Stenius
- Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Kine-Susann Dervola
- Department of Biochemistry, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Inger-Lise Bogen
- Department of Biochemistry, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Frode Fonnum
- Department of Biochemistry, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | | | - Dieter Schrenk
- Food Chemistry and Toxicology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Krister Halldin
- Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Helen Håkansson
- Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
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Walls AB, Eyjolfsson EM, Schousboe A, Sonnewald U, Waagepetersen HS. A subconvulsive dose of kainate selectively compromises astrocytic metabolism in the mouse brain in vivo. J Cereb Blood Flow Metab 2014; 34:1340-6. [PMID: 24824917 PMCID: PMC4126094 DOI: 10.1038/jcbfm.2014.88] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Revised: 04/09/2014] [Accepted: 04/16/2014] [Indexed: 11/09/2022]
Abstract
Despite the well-established use of kainate as a model for seizure activity and temporal lobe epilepsy, most studies have been performed at doses giving rise to general limbic seizures and have mainly focused on neuronal function. Little is known about the effect of lower doses of kainate on cerebral metabolism and particularly that associated with astrocytes. We investigated astrocytic and neuronal metabolism in the cerebral cortex of adult mice after treatment with saline (controls), a subconvulsive or a mildly convulsive dose of kainate. A combination of [1,2-(13)C]acetate and [1-(13)C]glucose was injected and subsequent nuclear magnetic resonance spectroscopy of cortical extracts was employed to distinctively map astrocytic and neuronal metabolism. The subconvulsive dose of kainate led to an instantaneous increase in the cortical lactate content, a subsequent reduction in the amount of [4,5-(13)C]glutamine and an increase in the calculated astrocytic TCA cycle activity. In contrast, the convulsive dose led to decrements in the cortical content and (13)C labeling of glutamate, glutamine, GABA, and aspartate. Evidence is provided that astrocytic metabolism is affected by a subconvulsive dose of kainate, whereas a higher dose is required to affect neuronal metabolism. The cerebral glycogen content was dose-dependently reduced by kainate supporting a role for glycogen during seizure activity.
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Affiliation(s)
- Anne B Walls
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Elvar M Eyjolfsson
- Department of Neuroscience, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway
| | - Arne Schousboe
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ursula Sonnewald
- Department of Neuroscience, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway
| | - Helle S Waagepetersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Hassel B, Dahlberg D, Mariussen E, Goverud IL, Antal EA, Tønjum T, Maehlen J. Brain infection with Staphylococcus aureus leads to high extracellular levels of glutamate, aspartate, γ-aminobutyric acid, and zinc. J Neurosci Res 2014; 92:1792-800. [PMID: 25043715 DOI: 10.1002/jnr.23444] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Revised: 05/06/2014] [Accepted: 06/01/2014] [Indexed: 11/08/2022]
Abstract
Staphylococcal brain infections may cause mental deterioration and epileptic seizures, suggesting interference with normal neurotransmission in the brain. We injected Staphylococcus aureus into rat striatum and found an initial 76% reduction in the extracellular level of glutamate as detected by microdialysis at 2 hr after staphylococcal infection. At 8 hr after staphylococcal infection, however, the extracellular level of glutamate had increased 12-fold, and at 20 hr it had increased >30-fold. The extracellular level of aspartate and γ-aminobutyric acid (GABA) also increased greatly. Extracellular Zn(2+) , which was estimated at ∼2.6 µmol/liter in the control situation, was increased by 330% 1-2.5 hr after staphylococcal infection and by 100% at 8 and 20 hr. The increase in extracellular glutamate, aspartate, and GABA appeared to reflect the degree of tissue damage. The area of tissue damage greatly exceeded the area of staphylococcal infiltration, pointing to soluble factors being responsible for cell death. However, the N-methyl-D-aspartate receptor antagonist MK-801 ameliorated neither tissue damage nor the increase in extracellular neuroactive amino acids, suggesting the presence of neurotoxic factors other than glutamate and aspartate. In vitro staphylococci incubated with glutamine and glucose formed glutamate, so bacteria could be an additional source of infection-related glutamate. We conclude that the dramatic increase in the extracellular concentration of neuroactive amino acids and zinc could interfere with neurotransmission in the surrounding brain tissue, contributing to mental deterioration and a predisposition to epileptic seizures, which are often seen in brain abscess patients.
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Affiliation(s)
- Bjørnar Hassel
- Department of Neurology, Oslo University Hospital, Rikshospitalet, Oslo, Norway; Norwegian Defense Research Establishment, Kjeller, Norway
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Lama S, Auer RN, Tyson R, Gallagher CN, Tomanek B, Sutherland GR. Lactate storm marks cerebral metabolism following brain trauma. J Biol Chem 2014; 289:20200-8. [PMID: 24849602 DOI: 10.1074/jbc.m114.570978] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Brain metabolism is thought to be maintained by neuronal-glial metabolic coupling. Glia take up glutamate from the synaptic cleft for conversion into glutamine, triggering glial glycolysis and lactate production. This lactate is shuttled into neurons and further metabolized. The origin and role of lactate in severe traumatic brain injury (TBI) remains controversial. Using a modified weight drop model of severe TBI and magnetic resonance (MR) spectroscopy with infusion of (13)C-labeled glucose, lactate, and acetate, the present study investigated the possibility that neuronal-glial metabolism is uncoupled following severe TBI. Histopathology of the model showed severe brain injury with subarachnoid and hemorrhage together with glial cell activation and positive staining for Tau at 90 min post-trauma. High resolution MR spectroscopy of brain metabolites revealed significant labeling of lactate at C-3 and C-2 irrespective of the infused substrates. Increased (13)C-labeled lactate in all study groups in the absence of ischemia implied activated astrocytic glycolysis and production of lactate with failure of neuronal uptake (i.e. a loss of glial sensing for glutamate). The early increase in extracellular lactate in severe TBI with the injured neurons rendered unable to pick it up probably contributes to a rapid progression toward irreversible injury and pan-necrosis. Hence, a method to detect and scavenge the excess extracellular lactate on site or early following severe TBI may be a potential primary therapeutic measure.
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Affiliation(s)
- Sanju Lama
- From the Department of Clinical Neurosciences and the Hotchkiss Brain Institute, Faculty of Medicine, University of Calgary, Calgary, Alberta T2N 2T9, Canada and
| | - Roland N Auer
- the Hôpital Ste-Justine, Département de Pathologie, Université de Montréal, Montreal, Québec H3T 1C5, Canada
| | - Randy Tyson
- From the Department of Clinical Neurosciences and the Hotchkiss Brain Institute, Faculty of Medicine, University of Calgary, Calgary, Alberta T2N 2T9, Canada and
| | - Clare N Gallagher
- From the Department of Clinical Neurosciences and the Hotchkiss Brain Institute, Faculty of Medicine, University of Calgary, Calgary, Alberta T2N 2T9, Canada and
| | - Boguslaw Tomanek
- From the Department of Clinical Neurosciences and the Hotchkiss Brain Institute, Faculty of Medicine, University of Calgary, Calgary, Alberta T2N 2T9, Canada and
| | - Garnette R Sutherland
- From the Department of Clinical Neurosciences and the Hotchkiss Brain Institute, Faculty of Medicine, University of Calgary, Calgary, Alberta T2N 2T9, Canada and
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42
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Nilsen LH, Witter MP, Sonnewald U. Neuronal and astrocytic metabolism in a transgenic rat model of Alzheimer's disease. J Cereb Blood Flow Metab 2014; 34:906-14. [PMID: 24594625 PMCID: PMC4013773 DOI: 10.1038/jcbfm.2014.37] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Revised: 01/18/2014] [Accepted: 01/25/2014] [Indexed: 12/23/2022]
Abstract
Regional hypometabolism of glucose in the brain is a hallmark of Alzheimer's disease (AD). However, little is known about the specific alterations of neuronal and astrocytic metabolism involved in homeostasis of glutamate and GABA in AD. Here, we investigated the effects of amyloid β (Aβ) pathology on neuronal and astrocytic metabolism and glial-neuronal interactions in amino acid neurotransmitter homeostasis in the transgenic McGill-R-Thy1-APP rat model of AD compared with healthy controls at age 15 months. Rats were injected with [1-(13)C]glucose and [1,2-(13)C]acetate, and extracts of the hippocampal formation as well as several cortical regions were analyzed using (1)H- and (13)C nuclear magnetic resonance spectroscopy and high-performance liquid chromatography. Reduced tricarboxylic acid cycle turnover was evident for glutamatergic and GABAergic neurons in hippocampal formation and frontal cortex, and for astrocytes in frontal cortex. Pyruvate carboxylation, which is necessary for de novo synthesis of amino acids, was decreased and affected the level of glutamine in hippocampal formation and those of glutamate, glutamine, GABA, and aspartate in the retrosplenial/cingulate cortex. Metabolic alterations were also detected in the entorhinal cortex. Overall, perturbations in energy- and neurotransmitter homeostasis, mitochondrial astrocytic and neuronal metabolism, and aspects of the glutamate-glutamine cycle were found in McGill-R-Thy1-APP rats.
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Affiliation(s)
- Linn Hege Nilsen
- Department of Neuroscience, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway
| | - Menno P Witter
- Centre for Neural Computation, Faculty of Medicine, Kavli Institute for Systems Neuroscience, Norwegian University of Science and Technology, Trondheim, Norway
| | - Ursula Sonnewald
- Department of Neuroscience, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway
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Astroglial d-serine is the endogenous co-agonist at the presynaptic NMDA receptor in rat entorhinal cortex. Neuropharmacology 2014; 83:118-27. [PMID: 24747728 DOI: 10.1016/j.neuropharm.2014.04.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 03/17/2014] [Accepted: 04/07/2014] [Indexed: 12/17/2022]
Abstract
Presynaptic NMDA receptors facilitate the release of glutamate at excitatory cortical synapses and are involved in regulation of synaptic dynamics and plasticity. At synapses in the entorhinal cortex these receptors are tonically activated and provide a positive feedback modulation of the level of background excitation. NMDA receptor activation requires obligatory occupation of a co-agonist binding site, and in the present investigation we have examined whether this site on the presynaptic receptor is activated by endogenous glycine or d-serine. We used whole-cell patch clamp recordings of spontaneous AMPA receptor-mediated synaptic currents from rat entorhinal cortex neurones in vitro as a monitor of presynaptic glutamate release. Addition of exogenous glycine or d-serine had minimal effects on spontaneous release, suggesting that the co-agonist site was endogenously activated and likely to be saturated in our slices. This was supported by the observation that a co-agonist site antagonist reduced the frequency of spontaneous currents. Depletion of endogenous glycine by enzymatic breakdown with a bacterial glycine oxidase had little effect on glutamate release, whereas d-serine depletion with a yeast d-amino acid oxidase significantly reduced glutamate release, suggesting that d-serine is the endogenous agonist. Finally, the effects of d-serine depletion were mimicked by compromising astroglial cell function, and this was rescued by exogenous d-serine, indicating that astroglial cells are the provider of the d-serine that tonically activates the presynaptic NMDA receptor. We discuss the significance of these observations for the aetiology of epilepsy and possible targeting of the presynaptic NMDA receptor in anticonvulsant therapy.
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13C NMR metabolomic evaluation of immediate and delayed mild hypothermia in cerebrocortical slices after oxygen-glucose deprivation. Anesthesiology 2013; 119:1120-36. [PMID: 23748856 DOI: 10.1097/aln.0b013e31829c2d90] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
BACKGROUND Mild brain hypothermia (32°-34°C) after human neonatal asphyxia improves neurodevelopmental outcomes. Astrocytes but not neurons have pyruvate carboxylase and an acetate uptake transporter. C nuclear magnetic resonance spectroscopy of rodent brain extracts after administering [1-C]glucose and [1,2-C]acetate can distinguish metabolic differences between glia and neurons, and tricarboxylic acid cycle entry via pyruvate dehydrogenase and pyruvate carboxylase. METHODS Neonatal rat cerebrocortical slices receiving a C-acetate/glucose mixture underwent a 45-min asphyxia simulation via oxygen-glucose-deprivation followed by 6 h of recovery. Protocols in three groups of N=3 experiments were identical except for temperature management. The three temperature groups were: normothermia (37°C), hypothermia (32°C for 3.75 h beginning at oxygen--glucose deprivation start), and delayed hypothermia (32°C for 3.75 h, beginning 15 min after oxygen-glucose deprivation start). Multivariate analysis of nuclear magnetic resonance metabolite quantifications included principal component analyses and the L1-penalized regularized regression algorithm known as the least absolute shrinkage and selection operator. RESULTS The most significant metabolite difference (P<0.0056) was [2-C]glutamine's higher final/control ratio for the hypothermia group (1.75±0.12) compared with ratios for the delayed (1.12±0.12) and normothermia group (0.94±0.06), implying a higher pyruvate carboxylase/pyruvate dehydrogenase ratio for glutamine formation. Least Absolute Shrinkage and Selection Operator found the most important metabolites associated with adenosine triphosphate preservation: [3,4-C]glutamate-produced via pyruvate dehydrogenase entry, [2-C]taurine-an important osmolyte and antioxidant, and phosphocreatine. Final principal component analyses scores plots suggested separate cluster formation for the hypothermia group, but with insufficient data for statistical significance. CONCLUSIONS Starting mild hypothermia simultaneously with oxygen-glucose deprivation, compared with delayed starting or no hypothermia, has higher pyruvate carboxylase throughput, suggesting that better glial integrity is one important neuroprotection mechanism of earlier hypothermia.
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Robertson CL, Saraswati M, Scafidi S, Fiskum G, Casey P, McKenna MC. Cerebral glucose metabolism in an immature rat model of pediatric traumatic brain injury. J Neurotrauma 2013; 30:2066-72. [PMID: 24032394 DOI: 10.1089/neu.2013.3007] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Altered cerebral metabolism and mitochondrial function have been identified in experimental and clinical studies of pediatric traumatic brain injury (TBI). Metabolic changes detected using (1)H (proton) magnetic resonance spectroscopy correlate with long-term outcomes in children after severe TBI. We previously identified early (4-h) and sustained (24-h and 7-day) abnormalities in brain metabolites after controlled cortical impact (CCI) in immature rats. The current study aimed to identify specific alterations of cerebral glucose metabolism at 24 h after TBI in immature rats. Rats (postnatal days 16-18) underwent CCI to the left parietal cortex. Sham rats underwent craniotomy only. Twenty-four hours after CCI, rats were injected (intraperitoneally) with [1,6-(13)C]glucose. Brains were removed, separated into hemispheres, and frozen. Metabolites were extracted with perchloric acid and analyzed using (1)H and (13)C-nuclear magnetic resonance spectroscopy. TBI resulted in decreases in N-acetylaspartate in both hemispheres, compared to sham contralateral. At 24 h after TBI, there was significant decrease in the incorporation of (13)C label into [3-(13)C]glutamate and [2-(13)C]glutamate in the injured brain. There were no differences in percent enrichment of [3-(13)C]glutamate, [4-(13)C]glutamate, [3-(13)C]glutamine, or [4-(13)C]glutamine. There was significantly lower percent enrichment of [2-(13)C]glutamate in both TBI sides and the sham craniotomy side, compared to sham contralateral. No differences were detected in enrichment of (13)C glucose label in [2-(13)C]glutamine, [2-(13)C]GABA (gamma-aminobutyric acid), [3-(13)C]GABA, or [4-(13)C]GABA, [3-(13)C]lactate, or [3-(13)C]alanine between groups. Results suggest that overall oxidative glucose metabolism in the immature brain recovers at 24 h after TBI. Specific reductions in [2-(13)C]glutamate could be the result of impairments in either neuronal or astrocytic metabolism. Future studies should aim to identify pathways leading to decreased metabolism and develop cell-selective "metabolic rescue."
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Affiliation(s)
- Courtney L Robertson
- 1 Department of Anesthesiology and Critical Care Medicine, Johns Hopkins School of Medicine , Baltimore, Maryland
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Hubbard JA, Hsu MS, Fiacco TA, Binder DK. Glial cell changes in epilepsy: Overview of the clinical problem and therapeutic opportunities. Neurochem Int 2013; 63:638-51. [DOI: 10.1016/j.neuint.2013.01.017] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Revised: 01/14/2013] [Accepted: 01/18/2013] [Indexed: 12/20/2022]
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Bjørnsen LP, Hadera MG, Zhou Y, Danbolt NC, Sonnewald U. The GLT-1 (EAAT2; slc1a2) glutamate transporter is essential for glutamate homeostasis in the neocortex of the mouse. J Neurochem 2013; 128:641-9. [PMID: 24224925 DOI: 10.1111/jnc.12509] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Revised: 10/18/2013] [Accepted: 10/21/2013] [Indexed: 12/24/2022]
Abstract
Glutamate is the major excitatory neurotransmitter, and is inactivated by cellular uptake catalyzed mostly by the glutamate transporter subtypes GLT-1 (EAAT2) and GLAST (EAAT1). Astrocytes express both GLT-1 and GLAST, while axon terminals in the neocortex only express GLT-1. To evaluate the role of GLT-1 in glutamate homeostasis, we injected GLT-1 knockout (KO) mice and wild-type littermates with [1-(13)C]glucose and [1,2-(13)C]acetate 15 min before euthanization. Metabolite levels were analyzed in extracts from neocortex and cerebellum and (13)C labeling in neocortex. Whereas the cerebellum in GLT-1-deficient mice had normal levels of glutamate, glutamine, and (13)C labeling of metabolites, glutamate level was decreased but labeling from [1-(13)C] glucose was unchanged in the neocortex. The contribution from pyruvate carboxylation toward labeling of these metabolites was unchanged. Labeling from [1,2-(13)C] acetate, originating in astrocytes, was decreased in glutamate and glutamine in the neocortex indicating reduced mitochondrial metabolism in astrocytes. The decreased amount of glutamate in the cortex indicates that glutamine transport into neurons is not sufficient to replenish glutamate lost because of neurotransmission and that GLT-1 plays a role in glutamate homeostasis in the cortex. Glutamate is the major excitatory neurotransmitter, and is inactivated by uptake via GLT-1 (EAAT2) and GLAST (EAAT1) transporters, while axon terminals in the neocortex only express GLT-1. To evaluate the role of GLT-1 in glutamate homeostasis, we used [1-(13)C]glucose and [1,2-(13)C]acetate injection and NMR spectroscopy. The results indicate that glutamine transport into neurons is not sufficient to replenish glutamate lost because of neurotransmission and that GLT-1 plays a role in glutamate homeostasis in the neocortex.
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Affiliation(s)
- Lars Petter Bjørnsen
- Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
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Astrocytic energetics during excitatory neurotransmission: What are contributions of glutamate oxidation and glycolysis? Neurochem Int 2013; 63:244-58. [PMID: 23838211 DOI: 10.1016/j.neuint.2013.06.015] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Revised: 06/19/2013] [Accepted: 06/24/2013] [Indexed: 12/23/2022]
Abstract
Astrocytic energetics of excitatory neurotransmission is controversial due to discrepant findings in different experimental systems in vitro and in vivo. The energy requirements of glutamate uptake are believed by some researchers to be satisfied by glycolysis coupled with shuttling of lactate to neurons for oxidation. However, astrocytes increase glycogenolysis and oxidative metabolism during sensory stimulation in vivo, indicating that other sources of energy are used by astrocytes during brain activation. Furthermore, glutamate uptake into cultured astrocytes stimulates glutamate oxidation and oxygen consumption, and glutamate maintains respiration as well as glucose. The neurotransmitter pool of glutamate is associated with the faster component of total glutamate turnover in vivo, and use of neurotransmitter glutamate to fuel its own uptake by oxidation-competent perisynaptic processes has two advantages, substrate is supplied concomitant with demand, and glutamate spares glucose for use by neurons and astrocytes. Some, but not all, perisynaptic processes of astrocytes in adult rodent brain contain mitochondria, and oxidation of only a small fraction of the neurotransmitter glutamate taken up into these structures would be sufficient to supply the ATP required for sodium extrusion and conversion of glutamate to glutamine. Glycolysis would, however, be required in perisynaptic processes lacking oxidative capacity. Three lines of evidence indicate that critical cornerstones of the astrocyte-to-neuron lactate shuttle model are not established and normal brain does not need lactate as supplemental fuel: (i) rapid onset of hemodynamic responses to activation delivers oxygen and glucose in excess of demand, (ii) total glucose utilization greatly exceeds glucose oxidation in awake rodents during activation, indicating that the lactate generated is released, not locally oxidized, and (iii) glutamate-induced glycolysis is not a robust phenotype of all astrocyte cultures. Various metabolic pathways, including glutamate oxidation and glycolysis with lactate release, contribute to cellular energy demands of excitatory neurotransmission.
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Nilsen LH, Rae C, Ittner LM, Götz J, Sonnewald U. Glutamate metabolism is impaired in transgenic mice with tau hyperphosphorylation. J Cereb Blood Flow Metab 2013; 33:684-91. [PMID: 23340677 PMCID: PMC3652703 DOI: 10.1038/jcbfm.2012.212] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
In neurodegenerative diseases including Alzheimer's disease and frontotemporal dementia, the protein tau is hyperphosphorylated and eventually aggregates to develop neurofibrillary tangles. Here, the consequences of tau hyperphosphorylation on both neuronal and astrocytic metabolism and amino-acid neurotransmitter homeostasis were assessed in transgenic mice expressing the pathogenic mutation P301L in the human tau gene (pR5 mice) compared with nontransgenic littermate controls. Mice were injected with the neuronal and astrocytic substrate [1-(13)C]glucose and the astrocytic substrate [1,2-(13)C]acetate. Hippocampus and cerebral cortex extracts were analyzed using (1)H and (13)C nuclear magnetic resonance spectroscopy, gas chromatography-mass spectrometry and high-performance liquid chromatography. The glutamate level was reduced in the hippocampus of pR5 mice, accompanied by reduced incorporation of (13)C label derived from [1-(13)C]glucose in glutamate. In the cerebral cortex, glucose utilization as well as turnover of glutamate, glutamine, and GABA, were increased. This was accompanied by a relative increase in production of glutamate via the pyruvate carboxylation pathway in cortex. Overall, we revealed that astrocytes as well as glutamatergic and GABAergic neurons in the cortex of pR5 mice were in a hypermetabolic state, whereas in the hippocampus, where expression levels of mutant human tau are the highest, glutamate homeostasis was impaired.
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Affiliation(s)
- Linn Hege Nilsen
- Department of Neuroscience, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway
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Neuron-astrocyte interactions, pyruvate carboxylation and the pentose phosphate pathway in the neonatal rat brain. Neurochem Res 2013; 39:556-69. [PMID: 23504293 DOI: 10.1007/s11064-013-1014-3] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Revised: 02/04/2013] [Accepted: 03/02/2013] [Indexed: 10/27/2022]
Abstract
Glucose and acetate metabolism and the synthesis of amino acid neurotransmitters, anaplerosis, glutamate-glutamine cycling and the pentose phosphate pathway (PPP) have been extensively investigated in the adult, but not the neonatal rat brain. To do this, 7 day postnatal (P7) rats were injected with [1-(13)C]glucose and [1,2-(13)C]acetate and sacrificed 5, 10, 15, 30 and 45 min later. Adult rats were injected and sacrificed after 15 min. To analyse pyruvate carboxylation and PPP activity during development, P7 rats received [1,2-(13)C]glucose and were sacrificed 30 min later. Brain extracts were analysed using (1)H- and (13)C-NMR spectroscopy. Numerous differences in metabolism were found between the neonatal and adult brain. The neonatal brain contained lower levels of glutamate, aspartate and N-acetylaspartate but similar levels of GABA and glutamine per mg tissue. Metabolism of [1-(13)C]glucose at the acetyl CoA stage was reduced much more than that of [1,2-(13)C]acetate. The transfer of glutamate from neurons to astrocytes was much lower while transfer of glutamine from astrocytes to glutamatergic neurons was relatively higher. However, transport of glutamine from astrocytes to GABAergic neurons was lower. Using [1,2-(13)C]glucose it could be shown that despite much lower pyruvate carboxylation, relatively more pyruvate from glycolysis was directed towards anaplerosis than pyruvate dehydrogenation in astrocytes. Moreover, the ratio of PPP/glucose-metabolism was higher. These findings indicate that only the part of the glutamate-glutamine cycle that transfers glutamine from astrocytes to neurons is operating in the neonatal brain and that compared to adults, relatively more glucose is prioritised to PPP and pyruvate carboxylation. Our results may have implications for the capacity to protect the neonatal brain against excitotoxicity and oxidative stress.
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