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Schirmbeck GH, Seady M, Fróes FT, Taday J, Da Ré C, Souza JM, Gonçalves CA, Leite MC. Long-term LPS systemic administration leads to memory impairment and disturbance in astrocytic homeostasis. Neurotoxicology 2023; 99:322-331. [PMID: 38006911 DOI: 10.1016/j.neuro.2023.11.009] [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: 07/03/2023] [Revised: 11/13/2023] [Accepted: 11/14/2023] [Indexed: 11/27/2023]
Abstract
Dementia is the most prevalent neurodegenerative disorder, characterized by progressive loss of memory and cognitive function. Inflammation is a major aspect in the progression of brain disorders, and inflammatory events have been associated with accelerated deterioration of cognitive function. In the present work, we investigated the impact of low-grade repeated inflammation stimuli induced by lipopolysaccharide (LPS) in hippocampal function and spatial memory. Adult male Wistar rats received a weekly injection of LPS (500 ug/kg) for sixteen weeks, eliciting systemic inflammation. Animals submitted to LPS presented impaired spatial memory and neuroinflammation. While neuronal synaptic markers such as synaptophysin and PSD-95 were unaltered, critical aspects of astrocyte homeostatic functions, such as glutamate uptake and glutathione content, were reduced. Also, glucose uptake and astrocyte lactate transporters were altered, suggesting a disturbance in the astrocyte-neuron coupling. Our present work demonstrates that long-term repeated systemic inflammation can lead to memory impairment and hippocampal metabolic disorders, especially regarding astrocyte function.
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Affiliation(s)
- Gabriel Henrique Schirmbeck
- Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Marina Seady
- Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Fernanda Telles Fróes
- Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Jéssica Taday
- Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Carollina Da Ré
- Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Jéssica Maria Souza
- Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Carlos Alberto Gonçalves
- Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Marina Concli Leite
- Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
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2
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Koda S, Hu J, Ju X, Sun G, Shao S, Tang RX, Zheng KY, Yan J. The role of glutamate receptors in the regulation of the tumor microenvironment. Front Immunol 2023; 14:1123841. [PMID: 36817470 PMCID: PMC9929049 DOI: 10.3389/fimmu.2023.1123841] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 01/20/2023] [Indexed: 02/04/2023] Open
Abstract
Glutamate, as one of the most important carbon sources in the TCA cycle, is central in metabolic processes that will subsequently influence tumor progression. Several factors can affect the expression of glutamate receptors, playing either a tumor-promoting or tumor-suppressor role in cancer. Thus, the activation of glutamate receptors by the ligand could play a role in tumor development as ample studies have demonstrated the expression of glutamate receptors in a broad range of tumor cells. Glutamate and its receptors are involved in the regulation of different immune cells' development and function, as suggested by the receptor expression in immune cells. The activation of glutamate receptors can enhance the effectiveness of the effector's T cells, or decrease the cytokine production in immunosuppressive myeloid-derived suppressor cells, increasing the antitumor immune response. These receptors are essential for the interaction between tumor and immune cells within the tumor microenvironment (TME) and the regulation of antitumor immune responses. Although the role of glutamate in the TCA cycle has been well studied, few studies have deeply investigated the role of glutamate receptors in the regulation of cancer and immune cells within the TME. Here, by a systematic review of the available data, we will critically assess the physiopathological relevance of glutamate receptors in the regulation of cancer and immune cells in the TME and provide some unifying hypotheses for futures research on the role of glutamate receptors in the immune modulation of the tumor.
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Affiliation(s)
- Stephane Koda
- Jiangsu Key Laboratory of Immunity and Metabolism, Department of Pathogenic Biology and Immunology, National Experimental Demonstration Center for Basic Medicine Education, Xuzhou Laboratory of Infection and Immunity, Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Jing Hu
- Department of Bioinformatics, School of Life Science, Xuzhou Medical University, Xuzhou, Jiangsu, China,Department of Genetics, Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Xiaoman Ju
- Jiangsu Key Laboratory of Immunity and Metabolism, Department of Pathogenic Biology and Immunology, National Experimental Demonstration Center for Basic Medicine Education, Xuzhou Laboratory of Infection and Immunity, Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Guowei Sun
- Jiangsu Key Laboratory of Immunity and Metabolism, Department of Pathogenic Biology and Immunology, National Experimental Demonstration Center for Basic Medicine Education, Xuzhou Laboratory of Infection and Immunity, Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Simin Shao
- Jiangsu Key Laboratory of Immunity and Metabolism, Department of Pathogenic Biology and Immunology, National Experimental Demonstration Center for Basic Medicine Education, Xuzhou Laboratory of Infection and Immunity, Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Ren-Xian Tang
- Jiangsu Key Laboratory of Immunity and Metabolism, Department of Pathogenic Biology and Immunology, National Experimental Demonstration Center for Basic Medicine Education, Xuzhou Laboratory of Infection and Immunity, Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Kui-Yang Zheng
- Jiangsu Key Laboratory of Immunity and Metabolism, Department of Pathogenic Biology and Immunology, National Experimental Demonstration Center for Basic Medicine Education, Xuzhou Laboratory of Infection and Immunity, Xuzhou Medical University, Xuzhou, Jiangsu, China,*Correspondence: Juming Yan, ; Kui-Yang Zheng,
| | - Juming Yan
- Jiangsu Key Laboratory of Immunity and Metabolism, Department of Pathogenic Biology and Immunology, National Experimental Demonstration Center for Basic Medicine Education, Xuzhou Laboratory of Infection and Immunity, Xuzhou Medical University, Xuzhou, Jiangsu, China,*Correspondence: Juming Yan, ; Kui-Yang Zheng,
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3
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Zhao J, Pike B, Huang J, Feng Z, Odle J, Lin X. Effects of medium chain triglycerides on hepatic fatty acid oxidation in clofibrate-fed newborn piglets. ANIMAL NUTRITION (ZHONGGUO XU MU SHOU YI XUE HUI) 2022; 12:334-344. [PMID: 36733783 PMCID: PMC9879763 DOI: 10.1016/j.aninu.2022.12.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 10/21/2022] [Accepted: 12/02/2022] [Indexed: 12/14/2022]
Abstract
To investigate whether increasing tricarboxylic acid (TCA) cycle activity and ketogenic capacity would augment fatty acid (FA) oxidation induced by the peroxisome proliferator-activated receptor-alpha (PPARα) agonist clofibrate, suckling newborn piglets (n = 54) were assigned to 8 groups following a 2 ( ± clofibrate) × 4 (glycerol succinate [SUC], triglycerides of 2-methylpentanoic acid [T2M], valeric acid [TC5] and hexanoic acid [TC6]) factorial design. Each group was fed an isocaloric milk formula containing either 0% or 0.35% clofibrate (wt/wt, dry matter basis) with 5% SUC, T2M, TC5 or TC6 for 5 d. Another 6 pigs served as newborn controls. Fatty acid oxidation was examined in fresh homogenates of liver collected on d 6 using [1-14C] palmitic acid (1 mM) as a substrate (0.265 μCi/μmol). Measurements were performed in the absence or presence of L-carnitine (1 mM) or inhibitors of 3-hydroxy-3-methylglutaryl-CoA synthase (L659699, 1.6 μM) or acetoacetate-CoA deacylase (iodoacetamide, 50 μM). Without clofibrate stimulation, 14C accumulation in CO2 was higher from piglets fed diets containing T2M and TC5 than SUC, but similar to those fed TC6. Under clofibrate stimulation, accumulation also was higher in homogenates from piglets fed TC5 than all other dietary treatments. Interactions between clofibrate and carnitine or the inhibitors were observed (P = 0.0004) for acid soluble products (ASP). In vitro addition of carnitine increased 14C-ASP (P < 0.0001) above all other treatments, regardless of clofibrate treatment. The percentage of 14C in CO2 was higher (P = 0.0023) in TC5 than in the control group. From these results we suggest that dietary supplementation of anaplerotic and ketogenic FA could impact FA oxidation and modify the metabolism of acetyl-CoA (product of β-oxidation) via alteration of TCA cycle activity, but the modification has no significant impact on the hepatic FA oxidative capacity induced by PPARα. In addition, the availability of carnitine is a critical element to maintain FA oxidation during the neonatal period.
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4
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Salcedo C, Andersen JV, Vinten KT, Pinborg LH, Waagepetersen HS, Freude KK, Aldana BI. Functional Metabolic Mapping Reveals Highly Active Branched-Chain Amino Acid Metabolism in Human Astrocytes, Which Is Impaired in iPSC-Derived Astrocytes in Alzheimer's Disease. Front Aging Neurosci 2021; 13:736580. [PMID: 34603012 PMCID: PMC8484639 DOI: 10.3389/fnagi.2021.736580] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Accepted: 08/04/2021] [Indexed: 01/04/2023] Open
Abstract
The branched-chain amino acids (BCAAs) leucine, isoleucine, and valine are important nitrogen donors for synthesis of glutamate, the main excitatory neurotransmitter in the brain. The glutamate carbon skeleton originates from the tricarboxylic acid (TCA) cycle intermediate α-ketoglutarate, while the amino group is derived from nitrogen donors such as the BCAAs. Disturbances in neurotransmitter homeostasis, mainly of glutamate, are strongly implicated in the pathophysiology of Alzheimer's disease (AD). The divergent BCAA metabolism in different cell types of the human brain is poorly understood, and so is the involvement of astrocytic and neuronal BCAA metabolism in AD. The goal of this study is to provide the first functional characterization of BCAA metabolism in human brain tissue and to investigate BCAA metabolism in AD pathophysiology using astrocytes and neurons derived from human-induced pluripotent stem cells (hiPSCs). Mapping of BCAA metabolism was performed using mass spectrometry and enriched [15N] and [13C] isotopes of leucine, isoleucine, and valine in acutely isolated slices of surgically resected cerebral cortical tissue from human brain and in hiPSC-derived brain cells carrying mutations in either amyloid precursor protein (APP) or presenilin-1 (PSEN-1). We revealed that both human astrocytes of acutely isolated cerebral cortical slices and hiPSC-derived astrocytes were capable of oxidatively metabolizing the carbon skeleton of BCAAs, particularly to support glutamine synthesis. Interestingly, hiPSC-derived astrocytes with APP and PSEN-1 mutations exhibited decreased amino acid synthesis of glutamate, glutamine, and aspartate derived from leucine metabolism. These results clearly demonstrate that there is an active BCAA metabolism in human astrocytes, and that leucine metabolism is selectively impaired in astrocytes derived from the hiPSC models of AD. This impairment in astrocytic BCAA metabolism may contribute to neurotransmitter and energetic imbalances in the AD brain.
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Affiliation(s)
- Claudia Salcedo
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jens V Andersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Kasper Tore Vinten
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Lars H Pinborg
- Epilepsy Clinic and Neurobiology Research Unit, Copenhagen University Hospital, University of Copenhagen, Copenhagen, Denmark
| | - Helle S Waagepetersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Kristine K Freude
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Blanca I Aldana
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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5
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Chen Y, Xu J, Chen Y. Regulation of Neurotransmitters by the Gut Microbiota and Effects on Cognition in Neurological Disorders. Nutrients 2021; 13:nu13062099. [PMID: 34205336 PMCID: PMC8234057 DOI: 10.3390/nu13062099] [Citation(s) in RCA: 229] [Impact Index Per Article: 76.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 06/14/2021] [Accepted: 06/16/2021] [Indexed: 12/11/2022] Open
Abstract
Emerging evidence indicates that gut microbiota is important in the regulation of brain activity and cognitive functions. Microbes mediate communication among the metabolic, peripheral immune, and central nervous systems via the microbiota–gut–brain axis. However, it is not well understood how the gut microbiome and neurons in the brain mutually interact or how these interactions affect normal brain functioning and cognition. We summarize the mechanisms whereby the gut microbiota regulate the production, transportation, and functioning of neurotransmitters. We also discuss how microbiome dysbiosis affects cognitive function, especially in neurodegenerative diseases such as Alzheimer’s disease and Parkinson’s disease.
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Affiliation(s)
- Yijing Chen
- Chinese Academy of Sciences Key Laboratory of Brain Connectome and Manipulation, Shenzhen Key Laboratory of Translational Research for Brain Diseases, The Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen–Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen 518055, China; (Y.C.); (J.X.)
| | - Jinying Xu
- Chinese Academy of Sciences Key Laboratory of Brain Connectome and Manipulation, Shenzhen Key Laboratory of Translational Research for Brain Diseases, The Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen–Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen 518055, China; (Y.C.); (J.X.)
- Shenzhen College of Advanced Technology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yu Chen
- Chinese Academy of Sciences Key Laboratory of Brain Connectome and Manipulation, Shenzhen Key Laboratory of Translational Research for Brain Diseases, The Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen–Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen 518055, China; (Y.C.); (J.X.)
- Shenzhen College of Advanced Technology, University of Chinese Academy of Sciences, Beijing 100049, China
- Guangdong Provincial Key Laboratory of Brain Science, Disease and Drug Development, HKUST Shenzhen Research Institute, Shenzhen–Hong Kong Institute of Brain Science, Shenzhen Fundamental Research Institutions, Shenzhen 518057, China
- Correspondence: ; Tel.: +86-755-26925498
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6
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Plotegher N, Filadi R, Pizzo P, Duchen MR. Excitotoxicity Revisited: Mitochondria on the Verge of a Nervous Breakdown. Trends Neurosci 2021; 44:342-351. [PMID: 33608137 DOI: 10.1016/j.tins.2021.01.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 12/03/2020] [Accepted: 01/08/2021] [Indexed: 12/30/2022]
Abstract
Excitotoxicity is likely to occur in pathological scenarios in which mitochondrial function is already compromised, shaping neuronal responses to glutamate. In fact, mitochondria sustain cell bioenergetics, tune intracellular Ca2+ dynamics, and regulate glutamate availability by using it as metabolic substrate. Here, we suggest the need to explore glutamate toxicity in the context of specific disease models in which it may occur, re-evaluating the impact of mitochondrial dysfunction on glutamate excitotoxicity. Our aim is to signpost new approaches, perhaps combining glutamate and pathways to rescue mitochondrial function, as therapeutic targets in neurological disorders.
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Affiliation(s)
| | - Riccardo Filadi
- Department of Biomedical Sciences, University of Padova, Padova, Italy; Neuroscience Institute, National Research Council (CNR), Padua, Italy
| | - Paola Pizzo
- Department of Biomedical Sciences, University of Padova, Padova, Italy; Neuroscience Institute, National Research Council (CNR), Padua, Italy
| | - Michael R Duchen
- Department of Cell and Developmental Biology, University College London, London, UK.
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7
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Mert S, Bulutoglu B, Chu C, Dylewski M, Lin FM, Yu YM, Yarmush ML, Sheridan RL, Uygun K. Multiorgan Metabolomics and Lipidomics Provide New Insights Into Fat Infiltration in the Liver, Muscle Wasting, and Liver-Muscle Crosstalk Following Burn Injury. J Burn Care Res 2020; 42:269-287. [PMID: 32877506 DOI: 10.1093/jbcr/iraa145] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Burn injury mediated hypermetabolic syndrome leads to increased mortality among severe burn victims, due to liver failure and muscle wasting. Metabolic changes may persist up to 2 years following the injury. Thus, understanding the underlying mechanisms of the pathology is crucially important to develop appropriate therapeutic approaches. We present detailed metabolomic and lipidomic analyses of the liver and muscle tissues in a rat model with a 30% body surface area burn injury located at the dorsal skin. Three hundred and thirty-eight of 1587 detected metabolites and lipids in the liver and 119 of 1504 in the muscle tissue exhibited statistically significant alterations. We observed excessive accumulation of triacylglycerols, decreased levels of S-adenosylmethionine, increased levels of glutamine and xenobiotics in the liver tissue. Additionally, the levels of gluconeogenesis, glycolysis, and tricarboxylic acid cycle metabolites are generally decreased in the liver. On the other hand, burn injury muscle tissue exhibits increased levels of acyl-carnitines, alpha-hydroxyisovalerate, ophthalmate, alpha-hydroxybutyrate, and decreased levels of reduced glutathione. The results of this preliminary study provide compelling observations that liver and muscle tissues undergo distinctly different changes during hypermetabolism, possibly reflecting liver-muscle crosstalk. The liver and muscle tissues might be exacerbating each other's metabolic pathologies, via excessive utilization of certain metabolites produced by each other.
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Affiliation(s)
- Safak Mert
- Burns Department, Shriners Hospitals for Children, Boston, Massachusetts.,Department of Surgery, Center for Engineering in Medicine and Surgery, Massachusetts General Hospital, Harvard Medical School, Boston
| | - Beyza Bulutoglu
- Burns Department, Shriners Hospitals for Children, Boston, Massachusetts.,Department of Surgery, Center for Engineering in Medicine and Surgery, Massachusetts General Hospital, Harvard Medical School, Boston
| | - Christopher Chu
- Burns Department, Shriners Hospitals for Children, Boston, Massachusetts.,Department of Surgery, Center for Engineering in Medicine and Surgery, Massachusetts General Hospital, Harvard Medical School, Boston
| | - Maggie Dylewski
- Burns Department, Shriners Hospitals for Children, Boston, Massachusetts
| | - Florence M Lin
- Burns Department, Shriners Hospitals for Children, Boston, Massachusetts
| | - Yong-Ming Yu
- Burns Department, Shriners Hospitals for Children, Boston, Massachusetts.,Department of Surgery, Center for Engineering in Medicine and Surgery, Massachusetts General Hospital, Harvard Medical School, Boston
| | - Martin L Yarmush
- Burns Department, Shriners Hospitals for Children, Boston, Massachusetts.,Department of Surgery, Center for Engineering in Medicine and Surgery, Massachusetts General Hospital, Harvard Medical School, Boston.,Department of Biomedical Engineering, Rutgers University, Piscataway, New Jersey
| | - Robert L Sheridan
- Burns Department, Shriners Hospitals for Children, Boston, Massachusetts
| | - Korkut Uygun
- Burns Department, Shriners Hospitals for Children, Boston, Massachusetts.,Department of Surgery, Center for Engineering in Medicine and Surgery, Massachusetts General Hospital, Harvard Medical School, Boston
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8
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Schousboe A. Astrocytic Metabolism Focusing on Glutamate Homeostasis: A Short Review Dedicated to Vittorio Gallo. Neurochem Res 2019; 45:522-525. [PMID: 31617053 DOI: 10.1007/s11064-019-02888-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 10/04/2019] [Accepted: 10/09/2019] [Indexed: 01/25/2023]
Abstract
A large number of studies have during the last several decades shown that astrocytes play a significant role in brain energy metabolism accounting for a considerable part of the oxygen uptake and the corresponding oxidative metabolism of glucose and lactate. Interestingly, it has become clear that in addition to these two major energy substrates, glutamate may be considered as an important alternative energy substrate and this is tightly coupled to its role as an excitatory neurotransmitter. Hence, this short review will link these events and provide an account of the role that Vittorio Gallo came to play as he coauthored a publication which demonstrated the usefulness of cultured cerebellar granule cells for studies of glutamate neurotransmission. Just by chance this study was published the same year that my own group published a similar study of glutamate uptake and release in a corresponding preparation of cultured neurons and astrocytes from cerebellum and cerebral cortex. Thus, it is a pleasure to dedicate this account of the role of astrocytes in glutamate neurotransmission to Vittorio Gallo whom I have had the pleasure of knowing for more than three decades.
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Affiliation(s)
- Arne Schousboe
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen Ø, Denmark.
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9
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Abstract
This review systematically examines the evidence for shifts in flux through energy generating biochemical pathways in Huntington’s disease (HD) brains from humans and model systems. Compromise of the electron transport chain (ETC) appears not to be the primary or earliest metabolic change in HD pathogenesis. Rather, compromise of glucose uptake facilitates glucose flux through glycolysis and may possibly decrease flux through the pentose phosphate pathway (PPP), limiting subsequent NADPH and GSH production needed for antioxidant protection. As a result, oxidative damage to key glycolytic and tricarboxylic acid (TCA) cycle enzymes further restricts energy production so that while basal needs may be met through oxidative phosphorylation, those of excessive stimulation cannot. Energy production may also be compromised by deficits in mitochondrial biogenesis, dynamics or trafficking. Restrictions on energy production may be compensated for by glutamate oxidation and/or stimulation of fatty acid oxidation. Transcriptional dysregulation generated by mutant huntingtin also contributes to energetic disruption at specific enzymatic steps. Many of the alterations in metabolic substrates and enzymes may derive from normal regulatory feedback mechanisms and appear oscillatory. Fine temporal sequencing of the shifts in metabolic flux and transcriptional and expression changes associated with mutant huntingtin expression remain largely unexplored and may be model dependent. Differences in disease progression among HD model systems at the time of experimentation and their varying states of metabolic compensation may explain conflicting reports in the literature. Progressive shifts in metabolic flux represent homeostatic compensatory mechanisms that maintain the model organism through presymptomatic and symptomatic stages.
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Affiliation(s)
- Janet M Dubinsky
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, USA
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10
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Mboge MY, Mahon BP, McKenna R, Frost SC. Carbonic Anhydrases: Role in pH Control and Cancer. Metabolites 2018; 8:E19. [PMID: 29495652 PMCID: PMC5876008 DOI: 10.3390/metabo8010019] [Citation(s) in RCA: 145] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 02/08/2018] [Accepted: 02/22/2018] [Indexed: 02/07/2023] Open
Abstract
The pH of the tumor microenvironment drives the metastatic phenotype and chemotherapeutic resistance of tumors. Understanding the mechanisms underlying this pH-dependent phenomenon will lead to improved drug delivery and allow the identification of new therapeutic targets. This includes an understanding of the role pH plays in primary tumor cells, and the regulatory factors that permit cancer cells to thrive. Over the last decade, carbonic anhydrases (CAs) have been shown to be important mediators of tumor cell pH by modulating the bicarbonate and proton concentrations for cell survival and proliferation. This has prompted an effort to inhibit specific CA isoforms, as an anti-cancer therapeutic strategy. Of the 12 active CA isoforms, two, CA IX and XII, have been considered anti-cancer targets. However, other CA isoforms also show similar activity and tissue distribution in cancers and have not been considered as therapeutic targets for cancer treatment. In this review, we consider all the CA isoforms and their possible role in tumors and their potential as targets for cancer therapy.
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Affiliation(s)
- Mam Y Mboge
- University of Florida, College of Medicine, Department of Biochemistry and Molecular Biology, P.O. Box 100245, Gainesville, FL 32610, USA.
| | - Brian P Mahon
- University of Florida, College of Medicine, Department of Biochemistry and Molecular Biology, P.O. Box 100245, Gainesville, FL 32610, USA.
| | - Robert McKenna
- University of Florida, College of Medicine, Department of Biochemistry and Molecular Biology, P.O. Box 100245, Gainesville, FL 32610, USA.
| | - Susan C Frost
- University of Florida, College of Medicine, Department of Biochemistry and Molecular Biology, P.O. Box 100245, Gainesville, FL 32610, USA.
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11
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Schousboe A. Metabolic signaling in the brain and the role of astrocytes in control of glutamate and GABA neurotransmission. Neurosci Lett 2018; 689:11-13. [PMID: 29378296 DOI: 10.1016/j.neulet.2018.01.038] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2017] [Revised: 01/19/2018] [Accepted: 01/20/2018] [Indexed: 12/15/2022]
Abstract
Neurotransmission mediated by the two amino acids glutamate and GABA is based on recycling of the two signaling molecules between the presynaptic nerve endings and the surrounding astrocytes. During the recycling process, a fraction of the transmitter pool is lost since both transmitters undergo oxidative metabolism. This loss must be replenished by de novo synthesis which involves the action of pyruvate carboxylase, aminotransferases, glutamate dehydrogenase and glutamine synthetase. Among these enzymes, pyruvate carboxylase and glutamine synthetase are selectively expressed in astrocytes and thus these cells are obligatory partners in synaptic replenishment of both glutamate and GABA. The cycling processes also involve transporters for glutamate, GABA and glutamine and the operation of these transporters is discussed. Additionally, astrocytes appear to be essential for production of the neuromodulators, citrate, glycine and d-serine, aspects that will be briefly discussed.
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Affiliation(s)
- Arne Schousboe
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2 Universitetsparken, DK-2100, Copenhagen, Denmark.
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