1
|
Lindquist BE. Spreading depolarizations pose critical energy challenges in acute brain injury. J Neurochem 2024; 168:868-887. [PMID: 37787065 PMCID: PMC10987398 DOI: 10.1111/jnc.15966] [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: 03/01/2023] [Revised: 08/08/2023] [Accepted: 09/10/2023] [Indexed: 10/04/2023]
Abstract
Spreading depolarization (SD) is an electrochemical wave of neuronal depolarization mediated by extracellular K+ and glutamate, interacting with voltage-gated and ligand-gated ion channels. SD is increasingly recognized as a major cause of injury progression in stroke and brain trauma, where the mechanisms of SD-induced neuronal injury are intimately linked to energetic status and metabolic impairment. Here, I review the established working model of SD initiation and propagation. Then, I summarize the historical and recent evidence for the metabolic impact of SD, transitioning from a descriptive to a mechanistic working model of metabolic signaling and its potential to promote neuronal survival and resilience. I quantify the energetic cost of restoring ionic gradients eroded during SD, and the extent to which ion pumping impacts high-energy phosphate pools and the energy charge of affected tissue. I link energy deficits to adaptive increases in the utilization of glucose and O2, and the resulting accumulation of lactic acid and CO2 downstream of catabolic metabolic activity. Finally, I discuss the neuromodulatory and vasoactive paracrine signaling mediated by adenosine and acidosis, highlighting these metabolites' potential to protect vulnerable tissue in the context of high-frequency SD clusters.
Collapse
Affiliation(s)
- Britta E Lindquist
- Department of Neurology, University of California, San Francisco, California, USA
- Gladstone Institute of Neurological Diseases, San Francisco, California, USA
- Zuckerberg San Francisco General Hospital and Trauma Center, San Francisco, California, USA
| |
Collapse
|
2
|
Aleya A, Mihok E, Pecsenye B, Jolji M, Kertész A, Bársony P, Vígh S, Cziaky Z, Máthé AB, Burtescu RF, Oláh NK, Neamțu AA, Turcuș V, Máthé E. Phytoconstituent Profiles Associated with Relevant Antioxidant Potential and Variable Nutritive Effects of the Olive, Sweet Almond, and Black Mulberry Gemmotherapy Extracts. Antioxidants (Basel) 2023; 12:1717. [PMID: 37760021 PMCID: PMC10525884 DOI: 10.3390/antiox12091717] [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: 07/15/2023] [Revised: 08/15/2023] [Accepted: 08/23/2023] [Indexed: 09/29/2023] Open
Abstract
The extracts of whole plants or specific organs from different plant species are gaining increasing attention for their phytotherapy applications. Accordingly, we prepared standardized gemmotherapy extracts (GTEs) from young shoots/buds of olive (Olea europaea), sweet almond (Prunus amygdalus), and black mulberry (Morus nigra), and analyzed the corresponding phytonutrient profiles. We identified 42, 103, and 109 phytonutrients in the olive, almond, and black mulberry GTEs, respectively, containing amino acids, vitamins, polyphenols, flavonoids, coumarins, alkaloids, iridoids, carboxylic acids, lignans, terpenoids, and others. In order to assess the physiological effects generated by the GTEs, we developed a translational nutrition model based on Drosophila melanogaster and Cyprinus carpio. The results indicate that GTEs could influence, to a variable extent, viability and ATP synthesis, even though both are dependent on the specific carbohydrate load of the applied diet and the amino acid and polyphenol pools provided by the GTEs. It seems, therefore, likely that the complex chemical composition of the GTEs offers nutritional properties that cannot be separated from the health-promoting mechanisms that ultimately increase viability and survival. Such an approach sets the paves the way for the nutritional genomic descriptions regarding GTE-associated health-promoting effects.
Collapse
Affiliation(s)
- Amina Aleya
- Doctoral School of Animal Science, Faculty of Agricultural and Food Sciences and Environmental Management, University of Debrecen, Böszörményi Str. 128, 4032 Debrecen, Hungary; (A.A.); (E.M.); (A.K.)
| | - Emőke Mihok
- Doctoral School of Animal Science, Faculty of Agricultural and Food Sciences and Environmental Management, University of Debrecen, Böszörményi Str. 128, 4032 Debrecen, Hungary; (A.A.); (E.M.); (A.K.)
| | - Bence Pecsenye
- Doctoral School of Nutrition and Food Science, Faculty of Agricultural and Food Sciences and Environmental Management, University of Debrecen, Böszörményi Str. 128, 4032 Debrecen, Hungary (M.J.)
- Institute of Nutrition Science, Faculty of Agricultural and Food Sciences and Environmental Management, University of Debrecen, Böszörményi Str. 128, 4032 Debrecen, Hungary;
| | - Maria Jolji
- Doctoral School of Nutrition and Food Science, Faculty of Agricultural and Food Sciences and Environmental Management, University of Debrecen, Böszörményi Str. 128, 4032 Debrecen, Hungary (M.J.)
| | - Attila Kertész
- Doctoral School of Animal Science, Faculty of Agricultural and Food Sciences and Environmental Management, University of Debrecen, Böszörményi Str. 128, 4032 Debrecen, Hungary; (A.A.); (E.M.); (A.K.)
| | - Péter Bársony
- Institute of Animal Science, Biotechnology and Nature Conservation, Faculty of Agricultural and Food Sciences and Environmental Management, University of Debrecen, Böszörményi Str. 128, 4032 Debrecen, Hungary;
| | - Szabolcs Vígh
- Agricultural and Molecular Research Institute, University of Nyíregyháza, Sóstói Str. 31, 4400 Nyíregyháza, Hungary; (S.V.); (Z.C.)
| | - Zoltán Cziaky
- Agricultural and Molecular Research Institute, University of Nyíregyháza, Sóstói Str. 31, 4400 Nyíregyháza, Hungary; (S.V.); (Z.C.)
| | - Anna-Beáta Máthé
- Doctoral School of Neuroscience, Faculty of Medicine, University of Debrecen, Nagyerdei Str. 94, 4032 Debrecen, Hungary;
| | | | - Neli-Kinga Oláh
- PlantExtrakt Ltd., 407059 Cluj, Romania; (R.F.B.)
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Vasile Goldiș Western University from Arad, L.Rebreanu Str. 86, 310414 Arad, Romania
| | - Andreea-Adriana Neamțu
- Department of Life Sciences, Faculty of Medicine, Vasile Goldiș Western University from Arad, L.Rebreanu Str. 86, 310414 Arad, Romania
| | - Violeta Turcuș
- Department of Life Sciences, Faculty of Medicine, Vasile Goldiș Western University from Arad, L.Rebreanu Str. 86, 310414 Arad, Romania
- CE-MONT Mountain Economy Center, Costin C. Kirițescu National Institute of Economic Research, Romanian Academy, Petreni Str. 49, 725700 Suceava, Romania
| | - Endre Máthé
- Institute of Nutrition Science, Faculty of Agricultural and Food Sciences and Environmental Management, University of Debrecen, Böszörményi Str. 128, 4032 Debrecen, Hungary;
- Department of Life Sciences, Faculty of Medicine, Vasile Goldiș Western University from Arad, L.Rebreanu Str. 86, 310414 Arad, Romania
| |
Collapse
|
3
|
Wei X, He Y, Wan H, Yin J, Lin B, Ding Z, Yang J, Zhou H. Integrated transcriptomics, proteomics and metabolomics to identify biomarkers of astragaloside IV against cerebral ischemic injury in rats. Food Funct 2023; 14:3588-3599. [PMID: 36946308 DOI: 10.1039/d2fo03030f] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2023]
Abstract
The herb Astragali Radix is a food-medicine herb. A major component of Astragali Radix, astragaloside IV (AS-IV), has neuroprotective effects in IS, but its mechanisms are not well understood. Our research used a transient middle cerebral artery occlusion (MCAO) rat model for longitudinal multi-omics analyses of the side of the brain affected by ischemia. Based on transcriptomic and proteomic analysis, we found that 396 differential expression targets were up-regulated and 114 differential expression targets were down-regulated. A total of 117 differential metabolites were identified based on metabonomics. Finally, we found 8 hub genes corresponding to the compound-reaction-enzyme-gene network using the Metscape plug-in for Cytoscape 3.7.1. We found that the related key metabolites were 3,4-dihydroxy-L-phenylalanine, 2-aminomuconate semialdehyde, (R)-3-hydroxybutanoate, etc., and the affected pathways were tyrosine metabolism, tryptophan metabolism, butanoate metabolism, purine metabolism, etc. We further validated these targets using 4D-PRM proteomics and found that seven targets were significantly different, including Aprt, Atic, Gaa, Galk1, Glb1, Me2, and Hexa. We aimed to uncover the mechanism of AS-IV in the treatment of ischemic brain injury through a comprehensive strategy combining transcriptomics, proteomics, and metabolomics.
Collapse
Affiliation(s)
- Xiaoyu Wei
- Zhejiang Chinese Medical University, Hangzhou, Zhejiang, 310053, P. R. China.
| | - Yu He
- Zhejiang Chinese Medical University, Hangzhou, Zhejiang, 310053, P. R. China.
| | - Haitong Wan
- Zhejiang Chinese Medical University, Hangzhou, Zhejiang, 310053, P. R. China.
| | - Junjun Yin
- Zhejiang Chinese Medical University, Hangzhou, Zhejiang, 310053, P. R. China.
| | - Bingying Lin
- Zhejiang Chinese Medical University, Hangzhou, Zhejiang, 310053, P. R. China.
| | - Zhishan Ding
- Zhejiang Chinese Medical University, Hangzhou, Zhejiang, 310053, P. R. China.
| | - Jiehong Yang
- Zhejiang Chinese Medical University, Hangzhou, Zhejiang, 310053, P. R. China.
| | - Huifen Zhou
- Zhejiang Chinese Medical University, Hangzhou, Zhejiang, 310053, P. R. China.
| |
Collapse
|
4
|
A Novel 5-Chloro- N-phenyl-1H-indole-2-carboxamide Derivative as Brain-Type Glycogen Phosphorylase Inhibitor: Validation of Target PYGB. Molecules 2023; 28:molecules28041697. [PMID: 36838691 PMCID: PMC9958726 DOI: 10.3390/molecules28041697] [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: 01/01/2023] [Revised: 02/07/2023] [Accepted: 02/09/2023] [Indexed: 02/12/2023] Open
Abstract
Brain-type glycogen phosphorylase (PYGB) inhibitors are recognized as prospective drugs for treating ischemic brain injury. We previously reported compound 1 as a novel glycogen phosphorylase inhibitor with brain-protective properties. In this study, we validated whether PYGB could be used as the therapeutic target for hypoxic-ischemic diseases and investigated whether compound 1 exerts a protective effect against astrocyte hypoxia/reoxygenation (H/R) injury by targeting PYGB. A gene-silencing strategy was initially applied to downregulate PYGB proteins in mouse astrocytes, which was followed by a series of cellular experiments with compound 1. Next, we compared relevant indicators that could prove the protective effect of compound 1 on brain injury, finding that after PYGB knockdown, compound 1 could not obviously alleviate astrocytes H/R injury, as evidenced by cell viability, which was not significantly improved, and lactate dehydrogenase (LDH) leakage rate, intracellular glucose content, and post-ischemic reactive oxygen species (ROS) level, which were not remarkably reduced. At the same time, cellular energy metabolism did not improve, and the degree of extracellular acidification was not downregulated after administration of compound 1 after PYGB knockdown. In addition, it could neither significantly increase the level of mitochondrial aerobic energy metabolism nor inhibit the expression of apoptosis-associated proteins. The above results indicate that compound 1 could target PYGB to exert its protective effect against cellular H/R injury in mouse astrocytes. Simultaneously, we further demonstrated that PYGB could be an efficient therapeutic target for ischemic-hypoxic diseases. This study provides a new reference for further in-depth study of the action mechanism of the efficacy of compound 1.
Collapse
|
5
|
A thermodynamic function of glycogen in brain and muscle. Prog Neurobiol 2020; 189:101787. [PMID: 32151532 DOI: 10.1016/j.pneurobio.2020.101787] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 01/30/2020] [Accepted: 03/03/2020] [Indexed: 11/20/2022]
Abstract
Brain and muscle glycogen are generally thought to function as local glucose reserves, for use during transient mismatches between glucose supply and demand. However, quantitative measures show that glucose supply is likely never rate-limiting for energy metabolism in either brain or muscle under physiological conditions. These tissues nevertheless do utilize glycogen during increased energy demand, despite the availability of free glucose, and despite the ATP cost of cycling glucose through glycogen polymer. This seemingly wasteful process can be explained by considering the effect of glycogenolysis on the amount of energy obtained from ATP (ΔG'ATP). The amount of energy obtained from ATP is reduced by elevations in inorganic phosphate (Pi). Glycogen utilization sequesters Pi in the glycogen phosphorylase reaction and in downstream phosphorylated glycolytic intermediates, thereby buffering Pi elevations and maximizing energy yield at sites of rapid ATP consumption. This thermodynamic effect of glycogen may be particularly important in the narrow, spatially constrained astrocyte processes that ensheath neuronal synapses and in cells such as astrocytes and myocytes that release Pi from phosphocreatine during energy demand. The thermodynamic effect may also explain glycolytic super-compensation in brain when glycogen is not available, and aspects of exercise physiology in muscle glycogen phosphorylase deficiency (McArdle disease).
Collapse
|
6
|
Wu L, Butler NJM, Swanson RA. Technical and Comparative Aspects of Brain Glycogen Metabolism. ADVANCES IN NEUROBIOLOGY 2019; 23:169-185. [DOI: 10.1007/978-3-030-27480-1_6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
|
7
|
Coggan JS, Keller D, Calì C, Lehväslaiho H, Markram H, Schürmann F, Magistretti PJ. Norepinephrine stimulates glycogenolysis in astrocytes to fuel neurons with lactate. PLoS Comput Biol 2018; 14:e1006392. [PMID: 30161133 PMCID: PMC6160207 DOI: 10.1371/journal.pcbi.1006392] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 09/27/2018] [Accepted: 07/24/2018] [Indexed: 12/20/2022] Open
Abstract
The mechanism of rapid energy supply to the brain, especially to accommodate the heightened metabolic activity of excited states, is not well-understood. We explored the role of glycogen as a fuel source for neuromodulation using the noradrenergic stimulation of glia in a computational model of the neural-glial-vasculature ensemble (NGV). The detection of norepinephrine (NE) by the astrocyte and the coupled cAMP signal are rapid and largely insensitive to the distance of the locus coeruleus projection release sites from the glia, implying a diminished impact for volume transmission in high affinity receptor transduction systems. Glucosyl-conjugated units liberated from glial glycogen by NE-elicited cAMP second messenger transduction winds sequentially through the glycolytic cascade, generating robust increases in NADH and ATP before pyruvate is finally transformed into lactate. This astrocytic lactate is rapidly exported by monocarboxylate transporters to the associated neuron, demonstrating that the astrocyte-to-neuron lactate shuttle activated by glycogenolysis is a likely fuel source for neuromodulation and enhanced neural activity. Altogether, the energy supply for both astrocytes and neurons can be supplied rapidly by glycogenolysis upon neuromodulatory stimulus. Although efficient compared to computers, the human brain utilizes energy at 10-fold the rate of other organs by mass. How the brain is supplied with sufficient on-demand energy to support its activity in the absence of neuronal storage capacity remains unknown. Neurons are not capable of meeting their own energy requirements, instead energy supply in the brain is managed by an oligocellular cartel composed of neurons, glia and the local vasculature (NGV), wherein glia can provide the ergogenic metabolite lactate to the neuron in a process called the astrocyte-to-neuron shuttle (ANLS). The only means of energy storage in the brain is glycogen, a polymerized form of glucose that is localized largely to astrocytes, but its exact role and conditions of use are not clear. In this computational model we show that neuromodulatory stimulation by norepinephrine induces astrocytes to recover glucosyl subunits from glycogen for use in a glycolytic process that favors the production of lactate. The ATP and NADH produced support metabolism in the astrocyte while the lactate is exported to feed the neuron. Thus, rapid energy demands by both neurons and glia in a stimulated brain can be met by glycogen mobilization.
Collapse
Affiliation(s)
- Jay S. Coggan
- Blue Brain Project, École Polytechnique Fédérale de Lausanne (EPFL), Geneva, Switzerland
- * E-mail: (JSC); (PJM)
| | - Daniel Keller
- Blue Brain Project, École Polytechnique Fédérale de Lausanne (EPFL), Geneva, Switzerland
| | - Corrado Calì
- Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Kingdom of Saudi Arabia
| | - Heikki Lehväslaiho
- Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Kingdom of Saudi Arabia
| | - Henry Markram
- Blue Brain Project, École Polytechnique Fédérale de Lausanne (EPFL), Geneva, Switzerland
| | - Felix Schürmann
- Blue Brain Project, École Polytechnique Fédérale de Lausanne (EPFL), Geneva, Switzerland
| | - Pierre J. Magistretti
- Blue Brain Project, École Polytechnique Fédérale de Lausanne (EPFL), Geneva, Switzerland
- Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Kingdom of Saudi Arabia
- * E-mail: (JSC); (PJM)
| |
Collapse
|
8
|
Hertz L, Chen Y. Glycogenolysis, an Astrocyte-Specific Reaction, is Essential for Both Astrocytic and Neuronal Activities Involved in Learning. Neuroscience 2017; 370:27-36. [PMID: 28668486 DOI: 10.1016/j.neuroscience.2017.06.025] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 06/10/2017] [Accepted: 06/19/2017] [Indexed: 01/26/2023]
Abstract
In brain glycogen, formed from glucose, is degraded (glycogenolysis) in astrocytes but not in neurons. Although most of the degradation follows the same pathway as glucose, its breakdown product, l-lactate, is released from astrocytes in larger amounts than glucose when glycogenolysis is activated by noradrenaline. However, this is not the case when glycogenolysis is activated by high potassium ion (K+) concentrations - possibly because noradrenaline in contrast to high K+ stimulates glycogenolysis by an increase not only in free cytosolic Ca2+ concentration ([Ca2+]i) but also in cyclic AMP (c-AMP), which may increase the expression of the monocarboxylate transporter through which it is released. Several transmitters activate glycogenolysis in astrocytes and do so at different time points after training. This stimulation is essential for memory consolidation because glycogenolysis is necessary for uptake of K+ and stimulates formation of glutamate from glucose, and therefore is needed both for removal of increased extracellular K+ following neuronal excitation (which initially occurs into astrocytes) and for formation of transmitter glutamate and GABA. In addition the released l-lactate has effects on neurons which are essential for learning and for learning-related long-term potentiation (LTP), including induction of the neuronal gene Arc/Arg3.1 and activation of gene cascades mediated by CREB and cofilin. Inhibition of glycogenolysis blocks learning, LTP and all related molecular events, but all changes can be reversed by injection of l-lactate. The effect of extracellular l-lactate is due to both astrocyte-mediated signaling which activates noradrenergic activity on all brain cells and to a minor uptake, possibly into dendritic spines.
Collapse
Affiliation(s)
- Leif Hertz
- Laboratory of Metabolic Brain Diseases, Institute of Metabolic Disease Research and Drug Development, China Medical University, Shenyang, PR China
| | - Ye Chen
- Henry M. Jackson Foundation, Bethesda, MD 20817, USA.
| |
Collapse
|
9
|
Hertz L, Chen Y. Importance of astrocytes for potassium ion (K+) homeostasis in brain and glial effects of K+ and its transporters on learning. Neurosci Biobehav Rev 2016; 71:484-505. [DOI: 10.1016/j.neubiorev.2016.09.018] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 08/12/2016] [Accepted: 09/23/2016] [Indexed: 10/20/2022]
|
10
|
Feuerstein D, Backes H, Gramer M, Takagaki M, Gabel P, Kumagai T, Graf R. Regulation of cerebral metabolism during cortical spreading depression. J Cereb Blood Flow Metab 2016; 36:1965-1977. [PMID: 26661217 PMCID: PMC5094298 DOI: 10.1177/0271678x15612779] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 08/25/2015] [Accepted: 09/08/2015] [Indexed: 12/01/2022]
Abstract
We analyzed the metabolic response to cortical spreading depression that drastically increases local energy demand to restore ion homeostasis. During single and multiple cortical spreading depressions in the rat cortex, we simultaneously monitored extracellular levels of glucose and lactate using rapid sampling microdialysis and glucose influx using 18 F-fluorodeoxyglucose positron emission tomography while tracking cortical spreading depression using laser speckle imaging. Combining the acquired data with steady-state requirements we developed a mass-conserving compartment model including neurons and glia that was consistent with the observed data. In summary, our findings are: (1) Early breakdown of glial glycogen provides a major source of energy during increased energy demand and leaves 80% of blood-borne glucose to neurons. (2) Lactate is used solely by neurons and only if extracellular lactate levels are >80% above normal. (3) Although the ratio of oxygen and glucose consumption transiently reaches levels <3, the major part (>90%) of the overall energy supply is from oxidative metabolism. (4) During cortical spreading depression, brain release of lactate exceeds its consumption suggesting that lactate is only a circumstantial energy substrate. Our findings provide a general scenario for the metabolic response to increased cerebral energy demand.
Collapse
Affiliation(s)
- Delphine Feuerstein
- Multimodal Imaging of Brain Metabolism, Max Planck Institute for Metabolism Research, Cologne, Germany
| | - Heiko Backes
- Multimodal Imaging of Brain Metabolism, Max Planck Institute for Metabolism Research, Cologne, Germany
| | - Markus Gramer
- Multimodal Imaging of Brain Metabolism, Max Planck Institute for Metabolism Research, Cologne, Germany
| | - Masatoshi Takagaki
- Department of Neurosurgery, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Paula Gabel
- Multimodal Imaging of Brain Metabolism, Max Planck Institute for Metabolism Research, Cologne, Germany
| | - Tetsuya Kumagai
- Department of Neurosurgery, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Rudolf Graf
- Multimodal Imaging of Brain Metabolism, Max Planck Institute for Metabolism Research, Cologne, Germany
| |
Collapse
|
11
|
Seidel JL, Escartin C, Ayata C, Bonvento G, Shuttleworth CW. Multifaceted roles for astrocytes in spreading depolarization: A target for limiting spreading depolarization in acute brain injury? Glia 2015; 64:5-20. [PMID: 26301517 DOI: 10.1002/glia.22824] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Revised: 01/31/2015] [Accepted: 03/02/2015] [Indexed: 12/17/2022]
Abstract
Spreading depolarizations (SDs) are coordinated waves of synchronous depolarization, involving large numbers of neurons and astrocytes as they spread slowly through brain tissue. The recent identification of SDs as likely contributors to pathophysiology in human subjects has led to a significant increase in interest in SD mechanisms, and possible approaches to limit the numbers of SDs or their deleterious consequences in injured brain. Astrocytes regulate many events associated with SD. SD initiation and propagation is dependent on extracellular accumulation of K(+) and glutamate, both of which involve astrocytic clearance. SDs are extremely metabolically demanding events, and signaling through astrocyte networks is likely central to the dramatic increase in regional blood flow that accompanies SD in otherwise healthy tissues. Astrocytes may provide metabolic support to neurons following SD, and may provide a source of adenosine that inhibits neuronal activity following SD. It is also possible that astrocytes contribute to the pathophysiology of SD, as a consequence of excessive glutamate release, facilitation of NMDA receptor activation, brain edema due to astrocyte swelling, or disrupted coupling to appropriate vascular responses after SD. Direct or indirect evidence has accumulated implicating astrocytes in many of these responses, but much remains unknown about their specific contributions, especially in the context of injury. Conversion of astrocytes to a reactive phenotype is a prominent feature of injured brain, and recent work suggests that the different functional properties of reactive astrocytes could be targeted to limit SDs in pathophysiological conditions.
Collapse
Affiliation(s)
- Jessica L Seidel
- Stroke and Neurovascular Regulation Lab, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts
| | - Carole Escartin
- Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Département des Sciences du Vivant (DSV), Institut d'Imagerie Biomédicale (I2BM), Molecular Imaging Center (MIRCen), CNRS UMR 9199, Université Paris-Sud, Université Paris-Saclay, F-92260 Fontenay-aux-Roses, France
| | - Cenk Ayata
- Stroke and Neurovascular Regulation Lab, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts.,Stroke Service and Neuroscience Intensive Care Unit, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts
| | - Gilles Bonvento
- Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Département des Sciences du Vivant (DSV), Institut d'Imagerie Biomédicale (I2BM), Molecular Imaging Center (MIRCen), CNRS UMR 9199, Université Paris-Sud, Université Paris-Saclay, F-92260 Fontenay-aux-Roses, France
| | - C William Shuttleworth
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, New Mexico
| |
Collapse
|
12
|
Abstract
The term spreading depolarization (SD) refers to waves of abrupt, sustained mass depolarization in gray matter of the CNS. SD, which spreads from neuron to neuron in affected tissue, is characterized by a rapid near-breakdown of the neuronal transmembrane ion gradients. SD can be induced by hypoxic conditions--such as from ischemia--and facilitates neuronal death in energy-compromised tissue. SD has also been implicated in migraine aura, where SD is assumed to ascend in well-nourished tissue and is typically benign. In addition to these two ends of the "SD continuum," an SD wave can propagate from an energy-depleted tissue into surrounding, well-nourished tissue, as is often the case in stroke and brain trauma. This review presents the neurobiology of SD--its triggers and propagation mechanisms--as well as clinical manifestations of SD, including overlaps and differences between migraine aura and stroke, and recent developments in neuromonitoring aimed at better diagnosis and more targeted treatments.
Collapse
Affiliation(s)
- Jens P Dreier
- Department of Neurology, Charité University Medicine Berlin, 10117 Berlin, Germany; Department of Experimental Neurology, Charité University Medicine Berlin, 10117 Berlin, Germany; Center for Stroke Research, Charité University Medicine Berlin, 10117 Berlin, Germany.
| | - Clemens Reiffurth
- Department of Experimental Neurology, Charité University Medicine Berlin, 10117 Berlin, Germany; Center for Stroke Research, Charité University Medicine Berlin, 10117 Berlin, Germany
| |
Collapse
|
13
|
Hertz L, Xu J, Song D, Du T, Li B, Yan E, Peng L. Astrocytic glycogenolysis: mechanisms and functions. Metab Brain Dis 2015; 30:317-33. [PMID: 24744118 DOI: 10.1007/s11011-014-9536-1] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Accepted: 02/24/2014] [Indexed: 12/18/2022]
Abstract
Until the demonstration little more than 20 years ago that glycogenolysis occurs during normal whisker stimulation glycogenolysis was regarded as a relatively uninteresting emergency procedure. Since then, a series of important astrocytic functions has been shown to be critically dependent on glycogenolytic activity to support the signaling mechanisms necessary for these functions to operate. This applies to glutamate formation and uptake and to release of ATP as a transmitter, stimulated by other transmitters or elevated K(+) concentrations and affecting not only other astrocytes but also most other brain cells. It is also relevant for astrocytic K(+) uptake both during the period when the extracellular K(+) concentration is still elevated after neuronal excitation, and capable of stimulating glycogenolytic activity, and during the subsequent undershoot after intense neuronal activity, when glycogenolysis may be stimulated by noradrenaline. Both elevated K(+) concentrations and several transmitters, including the β-adrenergic agonist isoproterenol and vasopressin increase free cytosolic Ca(2+) concentration in astrocytes, which stimulates phosphorylase kinase so that it activates the transformation of the inactive glycogen phosphorylase a to the active phosphorylase b. Contrary to common belief cyclic AMP plays at most a facilitatory role, and only when free cytosolic Ca(2+) concentration is also increased. Cyclic AMP is not increased during activation of glycogenolysis by either elevated K(+) concentrations or the stimulation of the serotonergic 5-HT(2B) receptor. Not all agents that stimulate glycogenolysis do so by directly activating phophorylase kinase--some do so by activating processes requiring glycogenolysis, e.g. for synthesis of glutamate.
Collapse
Affiliation(s)
- Leif Hertz
- Department of Clinical Pharmacology, China Medical University, No. 92 Beier Road, Heping District, 110001, Shenyang, Peoples' Republic of China
| | | | | | | | | | | | | |
Collapse
|
14
|
DiNuzzo M, Mangia S, Maraviglia B, Giove F. Does abnormal glycogen structure contribute to increased susceptibility to seizures in epilepsy? Metab Brain Dis 2015; 30:307-16. [PMID: 24643875 PMCID: PMC4169361 DOI: 10.1007/s11011-014-9524-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Accepted: 03/05/2014] [Indexed: 12/22/2022]
Abstract
Epilepsy is a family of brain disorders with a largely unknown etiology and high percentage of pharmacoresistance. The clinical manifestations of epilepsy are seizures, which originate from aberrant neuronal synchronization and hyperexcitability. Reactive astrocytosis, a hallmark of the epileptic tissue, develops into loss-of-function of glutamine synthetase, impairment of glutamate-glutamine cycle and increase in extracellular and astrocytic glutamate concentration. Here, we argue that chronically elevated intracellular glutamate level in astrocytes is instrumental to alterations in the metabolism of glycogen and leads to the synthesis of polyglucosans. Unaccessibility of glycogen-degrading enzymes to these insoluble molecules compromises the glycogenolysis-dependent reuptake of extracellular K(+) by astrocytes, thereby leading to increased extracellular K(+) and associated membrane depolarization. Based on current knowledge, we propose that the deterioration in structural homogeneity of glycogen particles is relevant to disruption of brain K(+) homeostasis and increased susceptibility to seizures in epilepsy.
Collapse
Affiliation(s)
- Mauro DiNuzzo
- MARBILab, Museo storico della fisica e Centro di studi e ricerche "Enrico Fermi", Rome, Italy,
| | | | | | | |
Collapse
|
15
|
Hertz L, Song D, Xu J, Peng L, Gibbs ME. Role of the Astrocytic Na(+), K(+)-ATPase in K(+) Homeostasis in Brain: K(+) Uptake, Signaling Pathways and Substrate Utilization. Neurochem Res 2015; 40:2505-16. [PMID: 25555706 DOI: 10.1007/s11064-014-1505-x] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Revised: 12/01/2014] [Accepted: 12/19/2014] [Indexed: 01/13/2023]
Abstract
This paper describes the roles of the astrocytic Na(+), K(+)-ATPase for K(+) homeostasis in brain. After neuronal excitation it alone mediates initial cellular re-accumulation of moderately increased extracellular K(+). At higher K(+) concentrations it is assisted by the Na(+), K(+), 2Cl(-) transporter NKCC1, which is Na(+), K(+)-ATPase-dependent, since it is driven by Na(+), K(+)-ATPase-created ion gradients. Besides stimulation by high K(+), NKCC1 is activated by extracellular hypertonicity. Intense excitation is followed by extracellular K(+) undershoot which is decreased by furosemide, an NKCC1 inhibitor. The powerful astrocytic Na(+), K(+)-ATPase accumulates excess extracellular K(+), since it is stimulated by above-normal extracellular K(+) concentrations. Subsequently K(+) is released via Kir4.1 channels (with no concomitant Na(+) transport) for re-uptake by the neuronal Na(+), K(+)-ATPase which is in-sensitive to increased extracellular K(+), but stimulated by intracellular Na(+) increase. Operation of the astrocytic Na(+), K(+)-ATPase depends upon Na(+), K(+)-ATPase/ouabain-mediated signaling and K(+)-stimulated glycogenolysis, needed in these non-excitable cells for passive uptake of extracellular Na(+), co-stimulating the intracellular Na(+)-sensitive site. A gradual, spatially dispersed release of astrocytically accumulated K(+) will therefore not re-activate the astrocytic Na(+), K(+)-ATPase. The extracellular K(+) undershoot is probably due to extracellular hypertonicity, created by a 3:2 ratio between Na(+), K(+)-ATPase-mediated Na(+) efflux and K(+) influx and subsequent NKCC1-mediated volume regulation. The astrocytic Na(+), K(+)-ATPase is also stimulated by β1-adrenergic signaling, which further stimulates hypertonicity-activation of NKCC1. Brain ischemia leads to massive extracellular K(+) increase and Ca(2+) decrease. A requirement of Na(+), K(+)-ATPase signaling for extracellular Ca(2+) makes K(+) uptake (and brain edema) selectively dependent upon β1-adrenergic signaling and inhibitable by its antagonists.
Collapse
Affiliation(s)
- Leif Hertz
- Laboratory of Brain Metabolic Diseases, Institute of Metabolic Disease Research and Drug Development, China Medical University, No. 77 Puhe Road, Shenbei District, Shenyang, 110122, People's Republic of China
| | - Dan Song
- Laboratory of Brain Metabolic Diseases, Institute of Metabolic Disease Research and Drug Development, China Medical University, No. 77 Puhe Road, Shenbei District, Shenyang, 110122, People's Republic of China
| | - Junnan Xu
- Laboratory of Brain Metabolic Diseases, Institute of Metabolic Disease Research and Drug Development, China Medical University, No. 77 Puhe Road, Shenbei District, Shenyang, 110122, People's Republic of China
| | - Liang Peng
- Laboratory of Brain Metabolic Diseases, Institute of Metabolic Disease Research and Drug Development, China Medical University, No. 77 Puhe Road, Shenbei District, Shenyang, 110122, People's Republic of China.
| | - Marie E Gibbs
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Clayton, VIC, Australia
| |
Collapse
|
16
|
Seidel JL, Faideau M, Aiba I, Pannasch U, Escartin C, Rouach N, Bonvento G, Shuttleworth CW. Ciliary neurotrophic factor (CNTF) activation of astrocytes decreases spreading depolarization susceptibility and increases potassium clearance. Glia 2015; 63:91-103. [PMID: 25092804 PMCID: PMC5141616 DOI: 10.1002/glia.22735] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Accepted: 07/17/2014] [Indexed: 11/08/2022]
Abstract
Waves of spreading depolarization (SD) have been implicated in the progressive expansion of acute brain injuries. SD can persist over several days, coincident with the time course of astrocyte activation, but little is known about how astrocyte activation may influence SD susceptibility. We examined whether activation of astrocytes modified SD threshold in hippocampal slices. Injection of a lentiviral vector encoding Ciliary neurotrophic factor (CNTF) into the hippocampus in vivo, led to sustained astrocyte activation, verified by up-regulation of glial fibrillary acidic protein (GFAP) at the mRNA and protein levels, as compared to controls injected with vector encoding LacZ. In acute brain slices from LacZ controls, localized 1M KCl microinjections invariably generated SD in CA1 hippocampus, but SD was never induced with this stimulus in CNTF tissues. No significant change in intrinsic excitability was observed in CA1 neurons, but excitatory synaptic transmission was significantly reduced in CNTF samples. mRNA levels of the predominantly astrocytic Na(+) /K(+) -ATPase pump α2 subunit were higher in CNTF samples, and the kinetics of extracellular K(+) transients during matched synaptic activation were consistent with increased K(+) uptake in CNTF tissues. Supporting a role for the Na(+) /K(+) -ATPase pump in increased SD threshold, ouabain, an inhibitor of the pump, was able to generate SD in CNTF tissues. These data support the hypothesis that activated astrocytes can limit SD onset via increased K(+) clearance and suggest that therapeutic strategies targeting these glial cells could improve the outcome following acute brain injuries associated with SD.
Collapse
Affiliation(s)
- Jessica L Seidel
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, New Mexico, USA
| | | | | | | | | | | | | | | |
Collapse
|
17
|
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.
Collapse
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
| |
Collapse
|
18
|
Pietrobon D, Moskowitz MA. Chaos and commotion in the wake of cortical spreading depression and spreading depolarizations. Nat Rev Neurosci 2014; 15:379-93. [PMID: 24857965 DOI: 10.1038/nrn3770] [Citation(s) in RCA: 269] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Punctuated episodes of spreading depolarizations erupt in the brain, encumbering tissue structure and function, and raising fascinating unanswered questions concerning their initiation and propagation. Linked to migraine aura and headache, cortical spreading depression contributes to the morbidity in the world's migraine with aura population. Even more ominously, erupting spreading depolarizations accelerate tissue damage during brain injury. The once-held view that spreading depolarizations may not exist in the human brain has changed, largely because of the discovery of migraine genes that confer cortical spreading depression susceptibility, the application of sophisticated imaging tools and efforts to interrogate their impact in the acutely injured human brain.
Collapse
Affiliation(s)
- Daniela Pietrobon
- Department of Biomedical Sciences and CNR Institute of Neuroscience, University of Padova 35121 Padova, Italy
| | - Michael A Moskowitz
- 1] Stroke and Neurovascular Regulation Laboratory, Departments of Radiology and Neurology, 149 13th Street, Room 6403, Massachusetts General Hospital, Charlestown, Massachusetts 02129, USA. [2] Department of Neurology, Harvard Medical School, Boston, Massachusetts, USA
| |
Collapse
|
19
|
Barreto GE, Capani F, Cabezas R. Cortical spreading depression and mitochondrial dysfunction with aging: lessons from ethanol abuse. Front Aging Neurosci 2014; 6:117. [PMID: 24959144 PMCID: PMC4051210 DOI: 10.3389/fnagi.2014.00117] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Accepted: 05/25/2014] [Indexed: 12/16/2022] Open
Affiliation(s)
- George E Barreto
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana Bogotá D.C., Colombia
| | - Francisco Capani
- Laboratorio de Citoarquitectura y Plasticidad Neuronal, Facultad de Medicina, Instituto de Investigaciones Cardiológicas Prof. Dr. Alberto C. Taquini (ININCA), UBA-CONICET Buenos Aires, Argentina
| | - Ricardo Cabezas
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana Bogotá D.C., Colombia
| |
Collapse
|
20
|
Broberg M, Pope KJ, Olsson T, Shuttleworth CW, Willoughby JO. Spreading depression: Evidence of five electroencephalogram phases. J Neurosci Res 2014; 92:1384-94. [DOI: 10.1002/jnr.23412] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Revised: 03/05/2014] [Accepted: 04/15/2014] [Indexed: 11/11/2022]
Affiliation(s)
- Marita Broberg
- Center for Neuroscience and Department of Neurology; Flinders University; Adelaide South Australia Australia
| | - Kenneth J. Pope
- School of Informatics and Engineering; Flinders University; Adelaide South Australia Australia
| | - Torsten Olsson
- Department of Signals and Systems; Chalmers University of Technology; Göteborg Sweden
| | - C. William Shuttleworth
- Department of Neurosciences; University of New Mexico School of Medicine; Albuquerque New Mexico
| | - John O. Willoughby
- Center for Neuroscience and Department of Neurology; Flinders University; Adelaide South Australia Australia
| |
Collapse
|
21
|
|
22
|
Carter RE, Seidel JL, Lindquist BE, Sheline CT, Shuttleworth CW. Intracellular Zn2+ accumulation enhances suppression of synaptic activity following spreading depolarization. J Neurochem 2013; 125:673-84. [PMID: 23495967 PMCID: PMC3666321 DOI: 10.1111/jnc.12237] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2013] [Revised: 03/05/2013] [Accepted: 03/11/2013] [Indexed: 12/27/2022]
Abstract
Spreading depolarization (SD) is a feed-forward wave that propagates slowly throughout brain tissue and recovery from SD involves substantial metabolic demand. Presynaptic Zn(2+) release and intracellular accumulation occurs with SD, and elevated intracellular Zn(2+) ([Zn(2+) ]i ) can impair cellular metabolism through multiple pathways. We tested here whether increased [Zn(2+) ]i could exacerbate the metabolic challenge of SD, induced by KCl, and delay recovery in acute murine hippocampal slices. [Zn(2+) ]i loading prior to SD, by transient ZnCl2 application with the Zn(2+) ionophore pyrithione (Zn/Pyr), delayed recovery of field excitatory post-synaptic potentials (fEPSPs) in a concentration-dependent manner, prolonged DC shifts, and significantly increased extracellular adenosine accumulation. These effects could be due to metabolic inhibition, occurring downstream of pyruvate utilization. Prolonged [Zn(2+) ]i accumulation prior to SD was required for effects on fEPSP recovery and consistent with this, endogenous synaptic Zn(2+) release during SD propagation did not delay recovery from SD. The effects of exogenous [Zn(2+) ]i loading were also lost in slices preconditioned with repetitive SDs, implying a rapid adaptation. Together, these results suggest that [Zn(2+) ]i loading prior to SD can provide significant additional challenge to brain tissue, and could contribute to deleterious effects of [Zn(2+) ]i accumulation in a range of brain injury models.
Collapse
Affiliation(s)
- Russell E. Carter
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM, USA
| | - Jessica L. Seidel
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM, USA
| | - Britta E. Lindquist
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM, USA
| | - Christian T. Sheline
- Department of Ophthalmology and the Neuroscience Center of Excellence LSU, Health Sciences Center, New Orleans, LA, USA
| | - C. William Shuttleworth
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM, USA
| |
Collapse
|
23
|
Risher WC, Croom D, Kirov SA. Persistent astroglial swelling accompanies rapid reversible dendritic injury during stroke-induced spreading depolarizations. Glia 2012; 60:1709-20. [PMID: 22821441 PMCID: PMC3435464 DOI: 10.1002/glia.22390] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Accepted: 06/20/2012] [Indexed: 11/10/2022]
Abstract
Spreading depolarizations are a key event in the pathophysiology of stroke, resulting in rapid dendritic beading, which represents acute damage to synaptic circuitry. The impact of spreading depolarizations on the real-time injury of astrocytes during ischemia is less clear. We used simultaneous in vivo 2-photon imaging and electrophysiological recordings in adult mouse somatosensory cortex to examine spreading depolarization-induced astroglial structural changes concurrently with signs of neuronal injury in the early periods of focal and global ischemia. Astrocytes in the metabolically compromised ischemic penumbra-like area showed a long lasting swelling response to spontaneous spreading depolarizations despite rapid dendritic recovery in a photothrombotic occlusion model of focal stroke. Astroglial swelling was often facilitated by recurrent depolarizations and the magnitude of swelling strongly correlated with the total duration of depolarization. In contrast, spreading depolarization-induced astroglial swelling was transient in normoxic healthy tissue. In a model of transient global ischemia, the occurrence of a single spreading depolarization elicited by a bilateral common carotid artery occlusion coincided with astroglial swelling alongside dendritic beading. With immediate reperfusion, dendritic beading subsides. Astroglial swelling was either transient during short ischemic periods distinguished by a short-lasting spreading depolarization, or persistent during severe ischemia characterized by a long-lasting depolarization with the ultraslow negative voltage component. We propose that persistent astroglial swelling is initiated and exacerbated during spreading depolarization in brain tissue with moderate to severe energy deficits, disrupting astroglial maintenance of normal homeostatic function thus contributing to the negative outcome of ischemic stroke as astrocytes fail to provide neuronal support.
Collapse
Affiliation(s)
- W. Christopher Risher
- Graduate Program in Neuroscience, Georgia Health Sciences University, Augusta, Georgia 30912
- Brain and Behavior Discovery Institute, Georgia Health Sciences University, Augusta, Georgia 30912
| | - Deborah Croom
- Department of Neurosurgery, Georgia Health Sciences University, Augusta, Georgia 30912
- Brain and Behavior Discovery Institute, Georgia Health Sciences University, Augusta, Georgia 30912
| | - Sergei A. Kirov
- Department of Neurosurgery, Georgia Health Sciences University, Augusta, Georgia 30912
- Brain and Behavior Discovery Institute, Georgia Health Sciences University, Augusta, Georgia 30912
| |
Collapse
|
24
|
Eid T, Behar K, Dhaher R, Bumanglag AV, Lee TSW. Roles of glutamine synthetase inhibition in epilepsy. Neurochem Res 2012; 37:2339-50. [PMID: 22488332 PMCID: PMC3731630 DOI: 10.1007/s11064-012-0766-5] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Revised: 03/15/2012] [Accepted: 03/22/2012] [Indexed: 10/28/2022]
Abstract
Glutamine synthetase (GS, E.C. 6.3.1.2) is a ubiquitous and highly compartmentalized enzyme that is critically involved in several metabolic pathways in the brain, including the glutamine-glutamate-GABA cycle and detoxification of ammonia. GS is normally localized to the cytoplasm of most astrocytes, with elevated concentrations of the enzyme being present in perivascular endfeet and in processes close to excitatory synapses. Interestingly, an increasing number of studies have indicated that the expression, distribution, or activity of brain GS is altered in several brain disorders, including Alzheimer's disease, schizophrenia, depression, suicidality, and mesial temporal lobe epilepsy (MTLE). Although the metabolic and functional sequelae of brain GS perturbations are not fully understood, it is likely that a deficiency in brain GS will have a significant biological impact due to the critical metabolic role of the enzyme. Furthermore, it is possible that restoration of GS in astrocytes lacking the enzyme could constitute a novel and highly specific therapy for these disorders. The goals of this review are to summarize key features of mammalian GS under normal conditions, and discuss the consequences of GS deficiency in brain disorders, specifically MTLE.
Collapse
Affiliation(s)
- Tore Eid
- Department of Laboratory Medicine, Yale University School of Medicine, 330 Cedar Street, P.O. Box 208035, New Haven, CT 06520-8035, USA.
| | | | | | | | | |
Collapse
|