1
|
Hou Y, Shang Y, Xu F, Li T, Li M, Wei L, Fan S, Hou W, Gou W, Shang H, Li Y. Ionizing radiation induces neurotoxicity in Xenopus laevis embryos through neuroactive ligand-receptor interaction pathway. ENVIRONMENTAL RESEARCH 2024; 256:119237. [PMID: 38810829 DOI: 10.1016/j.envres.2024.119237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 05/14/2024] [Accepted: 05/25/2024] [Indexed: 05/31/2024]
Abstract
Ionizing radiation (IR) poses a significant threat to both the natural environment and biological health. Exposure to specific doses of ionizing radiation early in an organism's development can lead to developmental toxicity, particularly neurotoxicity. Through experimentation with Xenopus laevis (X. laevis), we examined the effects of radiation on early developmental stage. Our findings revealed that radiation led to developmental abnormalities and mortality in X. laevis embryos in a dose-dependent manner, disrupting redox homeostasis and inducing cell apoptosis. Additionally, radiation caused neurotoxic effects, resulting in abnormal behavior and neuron damage in the embryos. Further investigation into the underlying mechanisms of radiation-induced neurotoxicity indicated the potential involvement of the neuroactive ligand-receptor interaction pathway, which was supported by RNA-Seq analysis. Validation of gene expression associated with this pathway and analysis of neurotransmitter levels confirmed our hypothesis. In addition, we further validated the important role of this signaling pathway in radiation-induced neurotoxicity through edaravone rescue experiments. This research establishes a valuable model for radiation damage studying and provides some insight into radiation-induced neurotoxicity mechanisms.
Collapse
Affiliation(s)
- Yue Hou
- State Key Laboratory of Advanced Medical Materials and Devices, Institute of Radiation Medicine, Chinese Academy of Medical Sciences & Peking Union Medical College, 300192, Tianjin, China
| | - Yue Shang
- State Key Laboratory of Advanced Medical Materials and Devices, Institute of Radiation Medicine, Chinese Academy of Medical Sciences & Peking Union Medical College, 300192, Tianjin, China
| | - Feifei Xu
- State Key Laboratory of Advanced Medical Materials and Devices, Institute of Radiation Medicine, Chinese Academy of Medical Sciences & Peking Union Medical College, 300192, Tianjin, China
| | - Tingyang Li
- State Key Laboratory of Advanced Medical Materials and Devices, Institute of Radiation Medicine, Chinese Academy of Medical Sciences & Peking Union Medical College, 300192, Tianjin, China
| | - Min Li
- State Key Laboratory of Advanced Medical Materials and Devices, Institute of Radiation Medicine, Chinese Academy of Medical Sciences & Peking Union Medical College, 300192, Tianjin, China
| | - Ling Wei
- School of Chinese Materia Medica, Guangdong Pharmaceutical University, 510006, Guangzhou, China
| | - Saijun Fan
- State Key Laboratory of Advanced Medical Materials and Devices, Institute of Radiation Medicine, Chinese Academy of Medical Sciences & Peking Union Medical College, 300192, Tianjin, China
| | - Wenbin Hou
- State Key Laboratory of Advanced Medical Materials and Devices, Institute of Radiation Medicine, Chinese Academy of Medical Sciences & Peking Union Medical College, 300192, Tianjin, China
| | - Wenfeng Gou
- State Key Laboratory of Advanced Medical Materials and Devices, Institute of Radiation Medicine, Chinese Academy of Medical Sciences & Peking Union Medical College, 300192, Tianjin, China.
| | - Haihua Shang
- State Key Laboratory of Advanced Medical Materials and Devices, Institute of Radiation Medicine, Chinese Academy of Medical Sciences & Peking Union Medical College, 300192, Tianjin, China.
| | - Yiliang Li
- State Key Laboratory of Advanced Medical Materials and Devices, Institute of Radiation Medicine, Chinese Academy of Medical Sciences & Peking Union Medical College, 300192, Tianjin, China.
| |
Collapse
|
2
|
Meier L, Bruginski E, Marafiga JR, Caus LB, Pasquetti MV, Calcagnotto ME, Campos FR. Hippocampal metabolic profile during epileptogenesis in the pilocarpine model of epilepsy. Biomed Chromatogr 2024; 38:e5820. [PMID: 38154955 DOI: 10.1002/bmc.5820] [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: 11/11/2023] [Revised: 12/02/2023] [Accepted: 12/07/2023] [Indexed: 12/30/2023]
Abstract
Temporal lobe epilepsy (TLE) is a common form of refractory epilepsy in adulthood. The metabolic profile of epileptogenesis is still poorly investigated. Elucidation of such a metabolic profile using animal models of epilepsy could help identify new metabolites and pathways involved in the mechanisms of epileptogenesis process. In this study, we evaluated the metabolic profile during the epileptogenesis periods. Using a pilocarpine model of epilepsy, we analyzed the global metabolic profile of hippocampal extracts by untargeted metabolomics based on ultra-performance liquid chromatography-high-resolution mass spectrometry, at three time points (3 h, 1 week, and 2 weeks) after status epilepticus (SE) induction. We demonstrated that epileptogenesis periods presented different hippocampal metabolic profiles, including alterations of metabolic pathways of amino acids and lipid metabolism. Six putative metabolites (tryptophan, N-acetylornithine, N-acetyl-L-aspartate, glutamine, adenosine, and cholesterol) showed significant different levels during epileptogenesis compared to their respective controls. These putative metabolites could be associated with the imbalance of neurotransmitters, mitochondrial dysfunction, and cell loss observed during both epileptogenesis and epilepsy. With these findings, we provided an overview of hippocampal metabolic profiles during different stages of epileptogenesis that could help investigate pathways and respective metabolites as predictive tools in epilepsy.
Collapse
Affiliation(s)
- Letícia Meier
- Biosciences and Mass Spectrometry Laboratory, Department of Pharmacy, Universidade Federal do Paraná, Curitiba, PR, Brazil
- Graduate Program in Pharmaceutical Science, Universidade Federal do Paraná, Curitiba, PR, Brazil
| | - Estevan Bruginski
- Biosciences and Mass Spectrometry Laboratory, Department of Pharmacy, Universidade Federal do Paraná, Curitiba, PR, Brazil
- Graduate Program in Pharmaceutical Science, Universidade Federal do Paraná, Curitiba, PR, Brazil
| | - Joseane Righes Marafiga
- Neurophysiology and Neurochemistry of Neuronal Excitability and Synaptic Plasticity Laboratory (NNNESP Lab.), Department of Biochemistry, ICBS, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
- Graduate Program in Biological Science: Biochemistry, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Letícia Barbieri Caus
- Neurophysiology and Neurochemistry of Neuronal Excitability and Synaptic Plasticity Laboratory (NNNESP Lab.), Department of Biochemistry, ICBS, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Mayara Vendramin Pasquetti
- Neurophysiology and Neurochemistry of Neuronal Excitability and Synaptic Plasticity Laboratory (NNNESP Lab.), Department of Biochemistry, ICBS, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Maria Elisa Calcagnotto
- Neurophysiology and Neurochemistry of Neuronal Excitability and Synaptic Plasticity Laboratory (NNNESP Lab.), Department of Biochemistry, ICBS, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
- Graduate Program in Biological Science: Biochemistry, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Francinete Ramos Campos
- Biosciences and Mass Spectrometry Laboratory, Department of Pharmacy, Universidade Federal do Paraná, Curitiba, PR, Brazil
- Graduate Program in Pharmaceutical Science, Universidade Federal do Paraná, Curitiba, PR, Brazil
| |
Collapse
|
3
|
Andersen JV, Schousboe A. Glial Glutamine Homeostasis in Health and Disease. Neurochem Res 2023; 48:1100-1128. [PMID: 36322369 DOI: 10.1007/s11064-022-03771-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 08/25/2022] [Accepted: 09/27/2022] [Indexed: 11/05/2022]
Abstract
Glutamine is an essential cerebral metabolite. Several critical brain processes are directly linked to glutamine, including ammonia homeostasis, energy metabolism and neurotransmitter recycling. Astrocytes synthesize and release large quantities of glutamine, which is taken up by neurons to replenish the glutamate and GABA neurotransmitter pools. Astrocyte glutamine hereby sustains the glutamate/GABA-glutamine cycle, synaptic transmission and general brain function. Cerebral glutamine homeostasis is linked to the metabolic coupling of neurons and astrocytes, and relies on multiple cellular processes, including TCA cycle function, synaptic transmission and neurotransmitter uptake. Dysregulations of processes related to glutamine homeostasis are associated with several neurological diseases and may mediate excitotoxicity and neurodegeneration. In particular, diminished astrocyte glutamine synthesis is a common neuropathological component, depriving neurons of an essential metabolic substrate and precursor for neurotransmitter synthesis, hereby leading to synaptic dysfunction. While astrocyte glutamine synthesis is quantitatively dominant in the brain, oligodendrocyte-derived glutamine may serve important functions in white matter structures. In this review, the crucial roles of glial glutamine homeostasis in the healthy and diseased brain are discussed. First, we provide an overview of cellular recycling, transport, synthesis and metabolism of glutamine in the brain. These cellular aspects are subsequently discussed in relation to pathological glutamine homeostasis of hepatic encephalopathy, epilepsy, Alzheimer's disease, Huntington's disease and amyotrophic lateral sclerosis. Further studies on the multifaceted roles of cerebral glutamine will not only increase our understanding of the metabolic collaboration between brain cells, but may also aid to reveal much needed therapeutic targets of several neurological pathologies.
Collapse
Affiliation(s)
- Jens V Andersen
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark.
| | - Arne Schousboe
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark.
| |
Collapse
|
4
|
Dahal A, Govindarajan K, Kar S. Administration of Kainic Acid Differentially Alters Astrocyte Markers and Transiently Enhanced Phospho-tau Level in Adult Rat Hippocampus. Neuroscience 2023; 516:27-41. [PMID: 36805001 DOI: 10.1016/j.neuroscience.2023.02.010] [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: 07/28/2022] [Revised: 02/04/2023] [Accepted: 02/12/2023] [Indexed: 02/18/2023]
Abstract
Kainic acid (KA), an analogue of the excitatory neurotransmitter glutamate, when administered systemically can trigger seizures and neuronal loss in a manner that mirrors the neuropathology of human mesial temporal lobe epilepsy (mTLE), which affects ∼50 million people globally. Evidence suggests that changes in astrocytes which precede neuronal damage play an important role in the degeneration of neurons and/or development of seizures in TLE pathogenesis. Additionally, a role for microtubule associated tau protein, involved in various neurodegenerative diseases including Alzheimer's disease, has also been suggested in the development of seizure and/or neurodegeneration in TLE pathogenesis. At present, possible alterations of different subtypes of astrocytes and their association, if any, with tau protein in TLE remain unclear. In this study, we evaluated alterations of different subtypes of astrocytes and phospho-/cleaved-tau levels in KA-treated rat model of TLE. Our results reveal that levels/expression of various astrocyte markers such as GFAP, vimentin, S100B, Aldh1L1, but not GS, are increased in the hippocampus of KA-treated rats. The levels/expression of both A1(C3+) and A2(S100A10+)-like astrocytes are also increased in KA-treated rats. Concurrently, the total (Tau1 and Tau5) and phospho-tau (AT270 and PHF1) levels are transiently enhanced following KA administration. Furthermore, the level/expression of cleaved-tau, which is apparent in a subset of GFAP-, S100B- and A2-positive astrocytes, are increased in KA-treated rats. These results, taken together, suggest a differential role for various astrocytic subpopulations and tau protein in the development of seizure and/or loss of neurons in KA model of TLE and possibly in human mTLE pathogenesis.
Collapse
Affiliation(s)
- Abhishek Dahal
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta T6G 2M8, Canada; Centre for Prions and Protein Folding Disease, University of Alberta, Edmonton, Alberta T6G 2M8, Canada
| | - Karthivashan Govindarajan
- Centre for Prions and Protein Folding Disease, University of Alberta, Edmonton, Alberta T6G 2M8, Canada; Department of Medicine, University of Alberta, Edmonton, Alberta T6G 2M8, Canada
| | - Satyabrata Kar
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta T6G 2M8, Canada; Centre for Prions and Protein Folding Disease, University of Alberta, Edmonton, Alberta T6G 2M8, Canada; Department of Medicine, University of Alberta, Edmonton, Alberta T6G 2M8, Canada.
| |
Collapse
|
5
|
Lea-Carnall CA, El-Deredy W, Stagg CJ, Williams SR, Trujillo-Barreto NJ. A mean-field model of glutamate and GABA synaptic dynamics for functional MRS. Neuroimage 2023; 266:119813. [PMID: 36528313 PMCID: PMC7614487 DOI: 10.1016/j.neuroimage.2022.119813] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 10/31/2022] [Accepted: 12/13/2022] [Indexed: 12/15/2022] Open
Abstract
Advances in functional magnetic resonance spectroscopy (fMRS) have enabled the quantification of activity-dependent changes in neurotransmitter concentrations in vivo. However, the physiological basis of the large changes in GABA and glutamate observed by fMRS (>10%) over short time scales of less than a minute remain unclear as such changes cannot be accounted for by known synthesis or degradation metabolic pathways. Instead, it has been hypothesized that fMRS detects shifts in neurotransmitter concentrations as they cycle from presynaptic vesicles, where they are largely invisible, to extracellular and cytosolic pools, where they are detectable. The present paper uses a computational modelling approach to demonstrate the viability of this hypothesis. A new mean-field model of the neural mechanisms generating the fMRS signal in a cortical voxel is derived. The proposed macroscopic mean-field model is based on a microscopic description of the neurotransmitter dynamics at the level of the synapse. Specifically, GABA and glutamate are assumed to cycle between three metabolic pools: packaged in the vesicles; active in the synaptic cleft; and undergoing recycling and repackaging in the astrocytic or neuronal cytosol. Computational simulations from the model are used to generate predicted changes in GABA and glutamate concentrations in response to different types of stimuli including pain, vision, and electric current stimulation. The predicted changes in the extracellular and cytosolic pools corresponded to those reported in empirical fMRS data. Furthermore, the model predicts a selective control mechanism of the GABA/glutamate relationship, whereby inhibitory stimulation reduces both neurotransmitters, whereas excitatory stimulation increases glutamate and decreases GABA. The proposed model bridges between neural dynamics and fMRS and provides a mechanistic account for the activity-dependent changes in the glutamate and GABA fMRS signals. Lastly, these results indicate that echo-time may be an important timing parameter that can be leveraged to maximise fMRS experimental outcomes.
Collapse
Affiliation(s)
- Caroline A Lea-Carnall
- School of Health Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester Academic Health Science Centre, UK.
| | - Wael El-Deredy
- Centro de Investigación y Desarrollo en Ingeniería en Salud, Universidad de Valparaíso, Chile; Valencian Graduate School and Research Network of Artificial Intelligence.; Department of Electronic Engineering, School of Engineering, Universitat de Val..ncia, Spain..
| | - Charlotte J Stagg
- Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK; MRC Brain Network Dynamics Unit, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Stephen R Williams
- Division of Informatics, Imaging and Data Science, University of Manchester, Manchester, UK
| | - Nelson J Trujillo-Barreto
- School of Health Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester Academic Health Science Centre, UK
| |
Collapse
|
6
|
Functional investigation of SLC1A2 variants associated with epilepsy. Cell Death Dis 2022; 13:1063. [PMID: 36543780 PMCID: PMC9772344 DOI: 10.1038/s41419-022-05457-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 11/15/2022] [Accepted: 11/18/2022] [Indexed: 12/24/2022]
Abstract
Epilepsy is a common neurological disorder and glutamate excitotoxicity plays a key role in epileptic pathogenesis. Astrocytic glutamate transporter GLT-1 is responsible for preventing excitotoxicity via clearing extracellular accumulated glutamate. Previously, three variants (G82R, L85P, and P289R) in SLC1A2 (encoding GLT-1) have been clinically reported to be associated with epilepsy. However, the functional validation and underlying mechanism of these GLT-1 variants in epilepsy remain undetermined. In this study, we reported that these disease-linked mutants significantly decrease glutamate uptake, cell membrane expression of the glutamate transporter, and glutamate-elicited current. Additionally, we found that these variants may disturbed stromal-interacting molecule 1 (STIM1)/Orai1-mediated store-operated Ca2+ entry (SOCE) machinery in the endoplasmic reticulum (ER), in which GLT-1 may be a new partner of SOCE. Furthermore, knock-in mice with disease-associated variants showed a hyperactive phenotype accompanied by reduced glutamate transporter expression. Therefore, GLT-1 is a promising and reliable therapeutic target for epilepsy interventions.
Collapse
|
7
|
van Vliet EA, Immonen R, Prager O, Friedman A, Bankstahl JP, Wright DK, O'Brien TJ, Potschka H, Gröhn O, Harris NG. A companion to the preclinical common data elements and case report forms for in vivo rodent neuroimaging: A report of the TASK3-WG3 Neuroimaging Working Group of the ILAE/AES Joint Translational Task Force. Epilepsia Open 2022. [PMID: 35962745 DOI: 10.1002/epi4.12643] [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: 12/12/2021] [Accepted: 02/01/2022] [Indexed: 11/10/2022] Open
Abstract
The International League Against Epilepsy/American Epilepsy Society (ILAE/AES) Joint Translational Task Force established the TASK3 working groups to create common data elements (CDEs) for various aspects of preclinical epilepsy research studies, which could help improve the standardization of experimental designs. In this article, we discuss CDEs for neuroimaging data that are collected in rodent models of epilepsy, with a focus on adult rats and mice. We provide detailed CDE tables and case report forms (CRFs), and with this companion manuscript, we discuss the methodologies for several imaging modalities and the parameters that can be collected.
Collapse
Affiliation(s)
- Erwin A van Vliet
- Center for Neuroscience, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
- Amsterdam UMC Location University of Amsterdam, Department of (Neuro)Pathology, Amsterdam Neuroscience, Amsterdam, The Netherlands
| | - Riikka Immonen
- A.I. Virtanen Institute, University of Eastern Finland, Kuopio, Finland
| | - Ofer Prager
- Departments of Physiology and Cell Biology, Cognitive and Brain Sciences, Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Alon Friedman
- Departments of Physiology and Cell Biology, Cognitive and Brain Sciences, Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
- Department of Medical Neuroscience and Brain Repair Center, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Jens P Bankstahl
- Department of Nuclear Medicine, Hannover Medical School, Hannover, Germany
| | - David K Wright
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Victoria, Australia
| | - Terence J O'Brien
- The Royal Melbourne Hospital, The University of Melbourne, The Alfred Hospital, Monash University, Melbourne, Victoria, Australia
| | - Heidrun Potschka
- Institute of Pharmacology, Toxicology, and Pharmacy, Ludwig-Maximilians-University, Munich, Germany
| | - Olli Gröhn
- A.I. Virtanen Institute, University of Eastern Finland, Kuopio, Finland
| | - Neil G Harris
- Department of Neurosurgery UCLA, UCLA Brain Injury Research Center, Los Angeles, California, USA
- Intellectual and Developmental Disabilities Research Center, UCLA, Los Angeles, California, USA
| |
Collapse
|
8
|
Mauri N, Richter H, Steffen F, Zölch N, Beckmann KM. Single-Voxel Proton Magnetic Resonance Spectroscopy of the Thalamus in Idiopathic Epileptic Dogs and in Healthy Control Dogs. Front Vet Sci 2022; 9:885044. [PMID: 35873693 PMCID: PMC9302964 DOI: 10.3389/fvets.2022.885044] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Accepted: 06/14/2022] [Indexed: 11/26/2022] Open
Abstract
The role of magnetic resonance spectroscopy (MRS) in the investigation of brain metabolites in epileptic syndromes in dogs has not been explored systematically to date. The aim of this study was to investigate metabolites in the thalamus in dogs affected by idiopathic epilepsy (IE) with and without antiepileptic drug treatment (AEDT) and to compare them to unaffected controls. Our hypothesis is that similar to humans with generalized epilepsy and loss of consciousness, N-acetyl aspartate (NAA) would be reduced, and glutamate–glutamine (Glx) would be increased in treated and untreated IE in comparison with the control group. In this prospective case–control study, Border Collie (BC) and Greater Swiss Mountain dog (GSMD) were divided into three groups: (1) healthy controls, IE with generalized tonic–clonic seizures with (2) and without (3) AEDT. A total of 41 BC and GSMD were included using 3 Tesla single-voxel proton MRS of the thalamus (PRESS localization, shortest TE, TR = 2000 ms, NSA = 240). After exclusion of 11 dogs, 30 dogs (18 IE and 12 healthy controls) remained available for analysis. Metabolite concentrations were estimated with LCModel using creatine as reference and compared using Kruskal–Wallis and Wilcoxon rank-sum tests. The Kruskal–Wallis test revealed significant differences in the NAA-to-creatine (p = 0.04) and Glx-to-creatine (p = 0.03) ratios between the three groups. The Wilcoxon rank-sum test further showed significant reduction in the NAA/creatine ratio in idiopathic epileptic dogs under AEDT compared to epileptic dogs without AEDT (p = 0.03) and compared to healthy controls (p = 0.03). In opposite to humans, Glx/creatine ratio was significantly reduced in dogs with IE under AEDT compared to epileptic dogs without AEDT (p = 0.03) and controls (p = 0.02). IE without AEDT and healthy controls did not show significant difference, neither in NAA/creatine (p = 0.60), nor in Glx-to-creatine (p = 0.55) ratio. In conclusion, MRS showed changes in dogs with IE and generalized seizures under AEDT, but not in those without AEDT. Based upon these results, MRS can be considered a useful advanced imaging technique for the evaluation of dogs with IE in the clinical and research settings.
Collapse
Affiliation(s)
- Nico Mauri
- Clinic for Diagnostic Imaging, Department of Diagnostics and Clinical Services, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
- Vetimage Diagnostik GmbH, Oberentfelden, Switzerland
| | - Henning Richter
- Clinic for Diagnostic Imaging, Department of Diagnostics and Clinical Services, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Frank Steffen
- Section of Neurology and Neurosurgery, Small Animal Clinic, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Niklaus Zölch
- Department of Forensic Medicine and Imaging, Institute of Forensic Medicine, University of Zurich, Zurich, Switzerland
| | - Katrin M. Beckmann
- Section of Neurology and Neurosurgery, Small Animal Clinic, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
- *Correspondence: Katrin M. Beckmann
| |
Collapse
|
9
|
Sakata Y, Sano K, Aoki S, Saitsu H, Takanashi JI. Neurochemistry evaluated by MR spectroscopy in a patient with SPTAN1-related developmental and epileptic encephalopathy. Brain Dev 2022; 44:415-420. [PMID: 35219564 DOI: 10.1016/j.braindev.2022.02.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 02/06/2022] [Accepted: 02/08/2022] [Indexed: 11/15/2022]
Abstract
BACKGROUND Mutation of the SPTAN1 gene, which encodes α-fodrin (non-erythrocyte α-II spectrin), is one of the causes of developmental and epileptic encephalopathies (DEEs). SPTAN1-related DEE is radiologically characterized by cerebral atrophy, especially due to white matter volume reduction, hypomyelination, pontocerebellar hypoplasia, and a thin corpus callosum, however, no neurochemical analysis has been reported. CASE REPORT A Japanese infant female presented with severe psychomotor delay, tonic spasms, and visual impairment. Whole-exome sequencing revealed a de novo variant of the SPTAN1 gene, leading to a diagnosis of SPTAN1-related DEE. MR spectroscopy at ages 5 months, 11 months, and 1 year and 4 months revealed decreased N-acetylaspartate and choline-containing compounds, and increased glutamate or glutamine. CONCLUSION The decreased concentrations of N-acetylaspartate and choline-containing compounds may have resulted from neuroaxonal network dysfunction and hypomyelination, respectively. The increased glutamate or glutamine may have reflected a disrupted glutamate-glutamine cycle caused by dysfunction of exocytosis, in which α-fodrin plays an important role. MR spectroscopy revealed neurochemical derangement in SPTAN1-related DEE, which may be a possible pathomechanism and will be useful for its diagnosis.
Collapse
Affiliation(s)
- Yuka Sakata
- Department of Pediatrics, Tokyo Women's Medical University Yachiyo Medical Center, Chiba, Japan
| | - Kentaro Sano
- Department of Pediatrics, Tokyo Women's Medical University Yachiyo Medical Center, Chiba, Japan
| | - Shintaro Aoki
- Department of Biochemistry, Hamamatsu University School of Medicine, Shizuoka, Japan
| | - Hirotomo Saitsu
- Department of Biochemistry, Hamamatsu University School of Medicine, Shizuoka, Japan
| | - Jun-Ichi Takanashi
- Department of Pediatrics, Tokyo Women's Medical University Yachiyo Medical Center, Chiba, Japan.
| |
Collapse
|
10
|
Abstract
Metabolomics is the laboratory analysis and scientific study of the metabolome—that is, the entire collection of small molecule chemicals in an organism. The metabolome represents the functional state of an organism and provides a multifaceted readout of the aggregate activity of endogenous (cellular) and exogenous (environmental) processes. In this review, we discuss how the integrative and dynamic properties of the metabolome create unique opportunities to study complex pathologies that evolve and oscillate over time, like epilepsy. We explain how the scientific progress and clinical applications of metabolomics remain hampered by biological and technical challenges, and we propose best practices to overcome these challenges so that metabolomics can be used in a rigorous and effective manner to further epilepsy research.
Collapse
Affiliation(s)
- Tore Eid
- Departments of Laboratory Medicine, of Neurosurgery, and of Cellular and Molecular Physiology, Yale School of Medicine, New Haven, CT, USA
- Clinical Chemistry Laboratory, Yale-New Haven Hospital, New Haven, CT, USA
| |
Collapse
|
11
|
Physiological synaptic activity and recognition memory require astroglial glutamine. Nat Commun 2022; 13:753. [PMID: 35136061 PMCID: PMC8826940 DOI: 10.1038/s41467-022-28331-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 01/07/2022] [Indexed: 12/23/2022] Open
Abstract
Presynaptic glutamate replenishment is fundamental to brain function. In high activity regimes, such as epileptic episodes, this process is thought to rely on the glutamate-glutamine cycle between neurons and astrocytes. However the presence of an astroglial glutamine supply, as well as its functional relevance in vivo in the healthy brain remain controversial, partly due to a lack of tools that can directly examine glutamine transfer. Here, we generated a fluorescent probe that tracks glutamine in live cells, which provides direct visual evidence of an activity-dependent glutamine supply from astroglial networks to presynaptic structures under physiological conditions. This mobilization is mediated by connexin43, an astroglial protein with both gap-junction and hemichannel functions, and is essential for synaptic transmission and object recognition memory. Our findings uncover an indispensable recruitment of astroglial glutamine in physiological synaptic activity and memory via an unconventional pathway, thus providing an astrocyte basis for cognitive processes. The authors present a fluorescent probe that tracks glutamine in live cells. They demonstrate the capabilities of the probe by providing direct visual evidence of an activity-dependent glutamine supply from astroglial networks to presynaptic structures under physiological conditions.
Collapse
|
12
|
Reyes-Ortega P, Soria-Ortiz MB, Rodríguez VM, Vázquez-Martínez EO, Díaz-Muñoz M, Reyes-Haro D. Anorexia disrupts glutamate-glutamine homeostasis associated with astroglia in the prefrontal cortex of young female rats. Behav Brain Res 2021; 420:113715. [PMID: 34906609 DOI: 10.1016/j.bbr.2021.113715] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 11/19/2021] [Accepted: 12/09/2021] [Indexed: 01/01/2023]
Abstract
Anorexia nervosa (AN) is an eating disorder characterized by self-starvation and excessive weight loss with a notorious prevalence in young women. The neurobiology of AN is unknown but murine models, like dehydration induced anorexia (DIA), reproduce weight loss and avoidance of food despite its availability. Astrocytes are known to provide homeostatic support to neurons, but it is little explored if anorexia affects this function. In this study, we tested if DIA disrupts glutamate-glutamine homeostasis associated with astrocytes in the prefrontal cortex (PFC) of young female rats. Our results showed that anorexia reduced the redox state, as well as endogenous glutamate and glutamine. These effects correlated with a reduced expression of the glutamate transporters (GLT-1 and GLAST) and glutamine synthetase, all of them are preferentially expressed by astrocytes. Accordingly, the expression of GFAP was reduced. Anorexia reduced the astrocyte density, promoted a de-ramified morphology, and augmented the de-ramified/ramified astrocyte ratio in the medial prefrontal cortex (mPFC) and orbitofrontal cortex (OFC), but not in the motor cortex (M2). The increase of a de-ramified phenotype correlated with increased expression of vimentin and nestin. Based on these results, we conclude that anorexia disrupts glutamate-glutamine homeostasis and the redox state associated with astrocyte dysfunction.
Collapse
Affiliation(s)
- Pamela Reyes-Ortega
- Universidad Nacional Autónoma de México, Instituto de Neurobiología, Campus Juriquilla, Boulevard Juriquilla 3001, Juriquilla, Querétaro CP76230, Mexico
| | - María Berenice Soria-Ortiz
- Universidad Nacional Autónoma de México, Instituto de Neurobiología, Campus Juriquilla, Boulevard Juriquilla 3001, Juriquilla, Querétaro CP76230, Mexico
| | - Verónica M Rodríguez
- Universidad Nacional Autónoma de México, Instituto de Neurobiología, Campus Juriquilla, Boulevard Juriquilla 3001, Juriquilla, Querétaro CP76230, Mexico
| | - Eva Olivia Vázquez-Martínez
- Universidad Nacional Autónoma de México, Instituto de Neurobiología, Campus Juriquilla, Boulevard Juriquilla 3001, Juriquilla, Querétaro CP76230, Mexico
| | - Mauricio Díaz-Muñoz
- Universidad Nacional Autónoma de México, Instituto de Neurobiología, Campus Juriquilla, Boulevard Juriquilla 3001, Juriquilla, Querétaro CP76230, Mexico
| | - Daniel Reyes-Haro
- Universidad Nacional Autónoma de México, Instituto de Neurobiología, Campus Juriquilla, Boulevard Juriquilla 3001, Juriquilla, Querétaro CP76230, Mexico.
| |
Collapse
|
13
|
Peterson AR, Garcia TA, Ford BD, Binder DK. Regulation of NRG-1-ErbB4 signaling and neuroprotection by exogenous neuregulin-1 in a mouse model of epilepsy. Neurobiol Dis 2021; 161:105545. [PMID: 34742879 DOI: 10.1016/j.nbd.2021.105545] [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: 09/15/2021] [Revised: 10/28/2021] [Accepted: 11/02/2021] [Indexed: 11/27/2022] Open
Abstract
Temporal lobe epilepsy (TLE) is the most common form of focal epilepsy. Dysregulation of glutamate transporters has been a common finding across animal models of epilepsy and in patients with TLE. In this study, we investigate NRG-1/ErbB4 signaling in epileptogenesis and the neuroprotective effects of NRG-1 treatment in a mouse model of temporal lobe epilepsy. Using immunohistochemistry, we report the first evidence for NRG-1/ErbB4-dependent selective upregulation of glutamate transporter EAAC1 and bihemispheric neuroprotection by exogeneous NRG-1 in the intrahippocampal kainic acid (IHKA) model of TLE. Our findings provide evidence that dysregulation of glutamate transporter EAAC1 contributes to the development of epilepsy and can be therapeutically targeted to reduce neuronal death following IHKA-induced status epilepticus (SE).
Collapse
Affiliation(s)
- Allison R Peterson
- Division of Biomedical Sciences, School of Medicine, Center for Glial-Neuronal Interactions, University of California, Riverside, CA, USA
| | - Terese A Garcia
- Division of Biomedical Sciences, School of Medicine, Center for Glial-Neuronal Interactions, University of California, Riverside, CA, USA
| | - Byron D Ford
- Division of Biomedical Sciences, School of Medicine, Center for Glial-Neuronal Interactions, University of California, Riverside, CA, USA
| | - Devin K Binder
- Division of Biomedical Sciences, School of Medicine, Center for Glial-Neuronal Interactions, University of California, Riverside, CA, USA.
| |
Collapse
|
14
|
Multi-omics in mesial temporal lobe epilepsy with hippocampal sclerosis: Clues into the underlying mechanisms leading to disease. Seizure 2021; 90:34-50. [DOI: 10.1016/j.seizure.2021.03.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2020] [Revised: 02/26/2021] [Accepted: 03/02/2021] [Indexed: 02/07/2023] Open
|
15
|
Hadar PN, Kini LG, Nanga RPR, Shinohara RT, Chen SH, Shah P, Wisse LEM, Elliott MA, Hariharan H, Reddy R, Detre JA, Stein JM, Das S, Davis KA. Volumetric glutamate imaging (GluCEST) using 7T MRI can lateralize nonlesional temporal lobe epilepsy: A preliminary study. Brain Behav 2021; 11:e02134. [PMID: 34255437 PMCID: PMC8413808 DOI: 10.1002/brb3.2134] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Accepted: 03/18/2021] [Indexed: 12/28/2022] Open
Abstract
INTRODUCTION Drug-resistant epilepsy patients show worse outcomes after resection when standard neuroimaging is nonlesional, which occurs in one-third of patients. In prior work, we employed 2-D glutamate imaging, Glutamate Chemical Exchange Saturation Transfer (GluCEST), to lateralize seizure onset in nonlesional temporal lobe epilepsy (TLE) based on increased ipsilateral GluCEST signal in the total hippocampus and hippocampal head. We present a significant advancement to single-slice GluCEST imaging, allowing for three-dimensional analysis of brain glutamate networks. METHODS The study population consisted of four MRI-negative, nonlesional TLE patients (two male, two female) with electrographically identified left temporal onset seizures. Imaging was conducted on a Siemens 7T MRI scanner using the CEST method for glutamate, while the advanced normalization tools (ANTs) pipeline and the Automated Segmentation of the Hippocampal Subfields (ASHS) method were employed for image analysis. RESULTS Volumetric GluCEST imaging was validated in four nonlesional TLE patients showing increased glutamate lateralized to the hippocampus of seizure onset (p = .048, with a difference among ipsilateral to contralateral GluCEST signal percentage ranging from -0.05 to 1.37), as well as increased GluCEST signal in the ipsilateral subiculum (p = .034, with a difference among ipsilateral to contralateral GluCEST signal ranging from 0.13 to 1.57). CONCLUSIONS The ability of 3-D, volumetric GluCEST to localize seizure onset down to the hippocampal subfield in nonlesional TLE is an improvement upon our previous 2-D, single-slice GluCEST method. Eventually, we hope to expand volumetric GluCEST to whole-brain glutamate imaging, thus enabling noninvasive analysis of glutamate networks in epilepsy and potentially leading to improved clinical outcomes.
Collapse
Affiliation(s)
- Peter N Hadar
- Penn Epilepsy Center, Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, PA, USA
| | - Lohith G Kini
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
| | - Ravi Prakash Reddy Nanga
- Center for Magnetic Resonance & Optical Imaging, Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
| | - Russell T Shinohara
- Department of Biostatistics, Epidemiology, and Informatics, University of Pennsylvania, Philadelphia, PA, USA
| | - Stephanie H Chen
- Penn Epilepsy Center, Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, PA, USA
| | - Preya Shah
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
| | - Laura E M Wisse
- Penn Image Computing & Science Lab, University of Pennsylvania, Philadelphia, PA, USA
| | - Mark A Elliott
- Center for Magnetic Resonance & Optical Imaging, Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
| | - Hari Hariharan
- Center for Magnetic Resonance & Optical Imaging, Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
| | - Ravinder Reddy
- Center for Magnetic Resonance & Optical Imaging, Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
| | - John A Detre
- Center for Magnetic Resonance & Optical Imaging, Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
| | - Joel M Stein
- Department of Radiology, University of Pennsylvania, Hospital of the University of Pennsylvania, Philadelphia, PA, USA
| | - Sandhitsu Das
- Penn Image Computing & Science Lab, University of Pennsylvania, Philadelphia, PA, USA
| | - Kathryn A Davis
- Penn Epilepsy Center, Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, PA, USA
| |
Collapse
|
16
|
Gong T, Liu Y, Chen Y, Lin L, Lin Y, Wang G. Focal corticarl dysplasia in epilepsy is associated with GABA increase. Neuroimage Clin 2021; 31:102763. [PMID: 34280836 PMCID: PMC8313738 DOI: 10.1016/j.nicl.2021.102763] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 07/08/2021] [Accepted: 07/10/2021] [Indexed: 12/01/2022]
Abstract
PURPOSE Focal cortical dysplasia (FCD) is a major cause of drug-resistant epilepsy; however the underlying epileptogenic mechanisms of FCD metabolism in epilepsy patients remain unclear. The aim of this study is to detect alterations of γ-aminobutyric acid (GABA), glutathione (GSH), and the composite of glutamate and glutamine (Glx) in MRI-typical and neuropathologically confirmed FCD-associated epilepsy using Hadamard Encoding and Reconstruction of Mega-Edited Spectroscopy (HERMES). MATERIALS AND METHODS Fourteen epileptic patients suspected to be caused by FCD and 14 healthy controls were enrolled prospectively in this study; all subjects underwent a 3 T MRI scan, including 3D T1 weighted imaging and HERMES. The GABA signal detected by HERMES also contains signals from macromolecules and homocarnosine, so it is referred as GABA+. Signals of GABA+, GSH and Glx detected by HERMES from tumor foci, contralateral cerebral regions, and healthy controls were quantified using Gannet. Fitting errors and signal to noise ratios (SNRs) of GABA + signals were also recorded. Differences of GABA+, GSH, Glx, fitting error and SNR of GABA + among three groups were analyzed using linear mixed effects models. RESULTS Twelve FCD-associated epilepsy patients (7 females, aged 21.9 ± 9.3 years) and 12 matched healthy controls (7 females, aged 22.8 ± 9.8 years) were finally enrolled in this study. ANOVA results indicated that GABA levels were significantly increased in FCD foci compared with contralateral regions (p = 0.008) and with healthy controls (p = 0.003), while no difference was found in GSH and Glx levels. No difference of fitting errors or SNR of GABA + was found among FCD foci, contralateral regions and healthy controls. CONCLUSIONS Increased GABA levels were found in FCD foci that indicated GABA may play a central role in the pathophysiology of FCD patients with epilepsy.
Collapse
Affiliation(s)
- Tao Gong
- Department of Radiology, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250021, China; MSunSoft Health Group, Shandong, China
| | - Yubo Liu
- Department of Radiology, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250021, China
| | - Yufan Chen
- Department of Radiology, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250021, China
| | | | - Youting Lin
- Department of Neurology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong 250021, China.
| | - Guangbin Wang
- Department of Radiology, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250021, China.
| |
Collapse
|
17
|
Flanagan B, McDaid L, Wade JJ, Toman M, Wong-Lin K, Harkin J. A Computational Study of Astrocytic GABA Release at the Glutamatergic Synapse: EAAT-2 and GAT-3 Coupled Dynamics. Front Cell Neurosci 2021; 15:682460. [PMID: 34322000 PMCID: PMC8312685 DOI: 10.3389/fncel.2021.682460] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 06/15/2021] [Indexed: 11/13/2022] Open
Abstract
Neurotransmitter dynamics within neuronal synapses can be controlled by astrocytes and reflect key contributors to neuronal activity. In particular, Glutamate (Glu) released by activated neurons is predominantly removed from the synaptic space by perisynaptic astrocytic transporters EAAT-2 (GLT-1). In previous work, we showed that the time course of Glu transport is affected by ionic concentration gradients either side of the astrocytic membrane and has the propensity for influencing postsynaptic neuronal excitability. Experimental findings co-localize GABA transporters GAT-3 with EAAT-2 on the perisynaptic astrocytic membrane. While these transporters are unlikely to facilitate the uptake of synaptic GABA, this paper presents simulation results which demonstrate the coupling of EAAT-2 and GAT-3, giving rise to the ionic-dependent reversed transport of GAT-3. The resulting efflux of GABA from the astrocyte to the synaptic space reflects an important astrocytic mechanism for modulation of hyperexcitability. Key results also illustrate an astrocytic-mediated modulation of synaptic neuronal excitation by released GABA at the glutamatergic synapse.
Collapse
Affiliation(s)
- Bronac Flanagan
- Intelligent Systems Research Centre, Ulster University, Derry, United Kingdom
| | | | | | | | | | | |
Collapse
|
18
|
Sarlo GL, Holton KF. Brain concentrations of glutamate and GABA in human epilepsy: A review. Seizure 2021; 91:213-227. [PMID: 34233236 DOI: 10.1016/j.seizure.2021.06.028] [Citation(s) in RCA: 59] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 06/22/2021] [Accepted: 06/24/2021] [Indexed: 12/27/2022] Open
Abstract
An imbalance between excitation and inhibition has been a longstanding proposed mechanism regarding ictogenesis and epileptogenesis. This imbalance is related to increased extracellular glutamate in the brain and/or reduction in GABA concentrations, leading to excitotoxicity, seizures, and cell death. This review aims to summarize the microdialysis and magnetic resonance spectroscopy (MRS) literature investigating glutamate and GABA concentrations in epilepsy patients, present limitations, and suggest future directions to help direct the search for novel epilepsy treatments. The majority of microdialysis studies demonstrated increased glutamate in epileptic regions either compared to control regions or to baseline levels; however, sample sizes were small, with some statistical comparisons missing. For the MRS research, two of six studies reported significant changes in glutamate levels compared to controls, though the results were mixed, with one reporting increased and the other reporting decreased glutamate levels. Eleven of 20 studies reported significant changes in Glx (glutamate + glutamine) or Glx ratios, with most reporting increased levels, except for a few epilepsy syndromes where reduced levels were reported. Few studies investigated GABA concentrations, with one microdialysis and four spectroscopy studies reporting increased GABA levels, and one study reporting decreased GABA in a different brain region. Based on this review, future research should account for medication use; include measurements of GABA, glutamate, and glutamine; use high-tesla strength MRI; and further evaluate the timing of microdialysis. Understanding the importance of brain glutamate and GABA levels in epilepsy may provide direction for future therapies and treatments.
Collapse
Affiliation(s)
- Gabrielle L Sarlo
- Department of Psychology, Behavior, Cognition and Neuroscience Program, American University, Washington DC, United States
| | - Kathleen F Holton
- Department of Health Studies, American University, Washington DC, United States; Center for Behavioral Neuroscience, American University, Washington DC, United States.
| |
Collapse
|
19
|
Ottka C, Weber C, Müller E, Lohi H. Serum NMR metabolomics uncovers multiple metabolic changes in phenobarbital-treated dogs. Metabolomics 2021; 17:54. [PMID: 34076758 PMCID: PMC8172515 DOI: 10.1007/s11306-021-01803-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 05/20/2021] [Indexed: 11/12/2022]
Abstract
INTRODUCTION Phenobarbital is a commonly used anticonvulsant for the treatment of canine epileptic seizures. In addition to its central nervous system (CNS) depressing effects, long-term phenobarbital administration affects liver function. However, broader metabolic consequences of phenobarbital treatment are poorly characterized. OBJECTIVES To identify metabolic changes in the sera of phenobarbital-treated dogs and to investigate the relationship between serum phenobarbital concentration and metabolite levels. METHODS Leftovers of clinical samples were used: 58 cases with phenobarbital concentrations ranging from 7.8 µg/mL to 50.8 µg/mL, and 25 controls. The study design was cross-sectional. The samples were analyzed by a canine-specific 1H NMR metabolomics platform. Differences between the case and control groups were evaluated by logistic regression. The linear relationship between metabolite and phenobarbital concentrations was evaluated using linear regression. RESULTS Increasing concentrations of glycoprotein acetyls, LDL particle size, palmitic acid, and saturated fatty acids, and decreasing concentrations of albumin, glutamine, histidine, LDL particle concentration, multiple HDL measures, and polyunsaturated fatty acids increased the odds of the sample belonging to the phenobarbital-treated group, having a p-value < .0033, and area under the curve (AUC) > .7. Albumin and glycoprotein acetyls had the best discriminative ability between the groups (AUC: .94). No linear associations between phenobarbital and metabolite concentrations were observed. CONCLUSION The identified metabolites are known to associate with, for example, liver and CNS function, inflammatory processes and drug binding. The lack of a linear association to phenobarbital concentration suggests that other factors than the blood phenobarbital concentration contribute to the magnitude of metabolic changes.
Collapse
Affiliation(s)
- Claudia Ottka
- PetBiomics Ltd., Helsinki, Finland.
- Department of Veterinary Biosciences, University of Helsinki, Helsinki, Finland.
- Department of Medical and Clinical Genetics, University of Helsinki, Helsinki, Finland.
- Folkhälsan Research Center, Helsinki, Finland.
| | | | | | - Hannes Lohi
- PetBiomics Ltd., Helsinki, Finland
- Department of Veterinary Biosciences, University of Helsinki, Helsinki, Finland
- Department of Medical and Clinical Genetics, University of Helsinki, Helsinki, Finland
- Folkhälsan Research Center, Helsinki, Finland
| |
Collapse
|
20
|
Sandhu MRS, Gruenbaum BF, Gruenbaum SE, Dhaher R, Deshpande K, Funaro MC, Lee TSW, Zaveri HP, Eid T. Astroglial Glutamine Synthetase and the Pathogenesis of Mesial Temporal Lobe Epilepsy. Front Neurol 2021; 12:665334. [PMID: 33927688 PMCID: PMC8078591 DOI: 10.3389/fneur.2021.665334] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Accepted: 03/19/2021] [Indexed: 12/21/2022] Open
Abstract
The enzyme glutamine synthetase (GS), also referred to as glutamate ammonia ligase, is abundant in astrocytes and catalyzes the conversion of ammonia and glutamate to glutamine. Deficiency or dysfunction of astrocytic GS in discrete brain regions have been associated with several types of epilepsy, including medically-intractable mesial temporal lobe epilepsy (MTLE), neocortical epilepsies, and glioblastoma-associated epilepsy. Moreover, experimental inhibition or deletion of GS in the entorhinal-hippocampal territory of laboratory animals causes an MTLE-like syndrome characterized by spontaneous, recurrent hippocampal-onset seizures, loss of hippocampal neurons, and in some cases comorbid depressive-like features. The goal of this review is to summarize and discuss the possible roles of astroglial GS in the pathogenesis of epilepsy.
Collapse
Affiliation(s)
| | - Benjamin F Gruenbaum
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Jacksonville, FL, United States
| | - Shaun E Gruenbaum
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Jacksonville, FL, United States
| | - Roni Dhaher
- Department of Neurosurgery, New Haven, CT, United States
| | | | - Melissa C Funaro
- Harvey Cushing/John Hay Whitney Medical Library, Yale University, New Haven, CT, United States
| | | | - Hitten P Zaveri
- Department of Neurology, Yale School of Medicine, New Haven, CT, United States
| | - Tore Eid
- Department of Laboratory Medicine, New Haven, CT, United States
| |
Collapse
|
21
|
Nada A, Leiva-Salinas C, Mahdi E, Mahmoud E, Ahsan H, Cousins JP. Multi-parametric magnetic resonance imaging evaluation of cerebral amyloid angiopathy related inflammation: Case series and review of literature. Clin Imaging 2021; 78:38-44. [PMID: 33740578 DOI: 10.1016/j.clinimag.2021.03.003] [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: 12/18/2020] [Revised: 02/04/2021] [Accepted: 03/05/2021] [Indexed: 10/21/2022]
Abstract
Cerebral amyloid angiopathy related inflammation is a rare disorder in the spectrum of cerebral amyloid angiopathy which is characterized by vascular and/or perivascular inflammation related to Aβ deposits. Clinically, the patient typically presents with acute to subacute encephalitis-like symptoms with focal neurological deficits, rapidly cognitive decline, and/or seizures. Typical magnetic resonance imaging findings include asymmetric mass-like non-enhancing white matter hyperintensity with scattered microhemorrhages. Additionally, in these cases diffusion weighted imaging, perfusion weighted imaging and magnetic resonance spectroscopy help to exclude neoplastic processes and could determine the correct diagnosis.
Collapse
Affiliation(s)
- Ayman Nada
- Department of Radiology, University of Missouri Health Care, One Hospital Drive, Columbia, MO, United States of America.
| | - Carlos Leiva-Salinas
- Department of Radiology, University of Missouri Health Care, One Hospital Drive, Columbia, MO, United States of America.
| | - Eman Mahdi
- Department of Radiology, University of Missouri Health Care, One Hospital Drive, Columbia, MO, United States of America.
| | - Esmat Mahmoud
- Department of Diagnostic and Interventional Radiology, National Cancer Institute, Cairo University, Egypt
| | - Humera Ahsan
- Department of Radiology, University of Missouri Health Care, One Hospital Drive, Columbia, MO, United States of America.
| | - Joseph Paul Cousins
- Department of Radiology, University of Missouri Health Care, One Hospital Drive, Columbia, MO, United States of America.
| |
Collapse
|
22
|
Binder DK, Steinhäuser C. Astrocytes and Epilepsy. Neurochem Res 2021; 46:2687-2695. [PMID: 33661442 DOI: 10.1007/s11064-021-03236-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 01/04/2021] [Accepted: 01/06/2021] [Indexed: 12/12/2022]
Abstract
Changes in astrocyte channels, transporters, and metabolism play a critical role in seizure generation and epilepsy. In particular, alterations in astrocyte potassium, glutamate, water and adenosine homeostasis and gap junctional coupling have all been associated with hyperexcitability and epileptogenesis (largely in temporal lobe epilepsy). Distinct astrocytic changes have also been identified in other types of epilepsy, such as tuberous sclerosis, tumor-associated epilepsy and post-traumatic epilepsy. Together, the emerging literature on astrocytes and epilepsy provides powerful rationale for distinct new therapeutic targets that are astrocyte-specific.
Collapse
Affiliation(s)
- Devin K Binder
- Center for Glial-Neuronal Interactions, Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA, USA.
| | - Christian Steinhäuser
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| |
Collapse
|
23
|
Hamelin S, Stupar V, Mazière L, Guo J, Labriji W, Liu C, Bretagnolle L, Parrot S, Barbier EL, Depaulis A, Fauvelle F. In vivo γ-aminobutyric acid increase as a biomarker of the epileptogenic zone: An unbiased metabolomics approach. Epilepsia 2020; 62:163-175. [PMID: 33258489 DOI: 10.1111/epi.16768] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 11/03/2020] [Accepted: 11/03/2020] [Indexed: 12/13/2022]
Abstract
OBJECTIVE Following surgery, focal seizures relapse in 20% to 50% of cases due to the difficulty of delimiting the epileptogenic zone (EZ) by current imaging or electrophysiological techniques. Here, we evaluate an unbiased metabolomics approach based on ex vivo and in vivo nuclear magnetic resonance spectroscopy (MRS) methods to discriminate the EZ in a mouse model of mesiotemporal lobe epilepsy (MTLE). METHODS Four weeks after unilateral injection of kainic acid (KA) into the dorsal hippocampus of mice (KA-MTLE model), we analyzed hippocampal and cortical samples with high-resolution magic angle spinning (HRMAS) magnetic resonance spectroscopy (MRS). Using advanced multivariate statistics, we identified the metabolites that best discriminate the injected dorsal hippocampus (EZ) and developed an in vivo MEGAPRESS MRS method to focus on the detection of these metabolites in the same mouse model. RESULTS Multivariate analysis of HRMAS data provided evidence that γ-aminobutyric acid (GABA) is largely increased in the EZ of KA-MTLE mice and is the metabolite that best discriminates the EZ when compared to sham and, more importantly, when compared to adjacent brain regions. These results were confirmed by capillary electrophoresis analysis and were not reversed by a chronic exposition to an antiepileptic drug (carbamazepine). Then, using in vivo noninvasive GABA-edited MRS, we confirmed that a high GABA increase is specific to the injected hippocampus of KA-MTLE mice. SIGNIFICANCE Our strategy using ex vivo MRS-based untargeted metabolomics to select the most discriminant metabolite(s), followed by in vivo MRS-based targeted metabolomics, is an unbiased approach to accurately define the EZ in a mouse model of focal epilepsy. Results suggest that GABA is a specific biomarker of the EZ in MTLE.
Collapse
Affiliation(s)
- Sophie Hamelin
- Grenoble Institut Neurosciences (GIN), Grenoble Alpes University, Inserm, U1216, Grenoble, France
| | - Vasile Stupar
- Grenoble Institut Neurosciences (GIN), Grenoble Alpes University, Inserm, U1216, Grenoble, France.,Grenoble Alpes University Hospital Center, Grenoble Alpes University, Inserm, US17, CNRS, UMS 3552, IRMaGe, Grenoble, France
| | - Lucile Mazière
- Grenoble Institut Neurosciences (GIN), Grenoble Alpes University, Inserm, U1216, Grenoble, France
| | - Jia Guo
- Lyon Neuroscience Research Center, NeuroDialyTics, Inserm U1028, CNRS, UMR5292, Lyon 1 University, Bron, France
| | - Wafae Labriji
- Grenoble Institut Neurosciences (GIN), Grenoble Alpes University, Inserm, U1216, Grenoble, France
| | - Chen Liu
- Department of Electrical Engineering, Columbia University, New York, NY, USA
| | - Ludiwine Bretagnolle
- Grenoble Institut Neurosciences (GIN), Grenoble Alpes University, Inserm, U1216, Grenoble, France
| | - Sandrine Parrot
- Lyon Neuroscience Research Center, NeuroDialyTics, Inserm U1028, CNRS UMR5292, Bron, France
| | - Emmanuel L Barbier
- Grenoble Institut Neurosciences (GIN), Grenoble Alpes University, Inserm, U1216, Grenoble, France.,Grenoble Alpes University Hospital Center, Grenoble Alpes University, Inserm, US17, CNRS, UMS 3552, IRMaGe, Grenoble, France
| | - Antoine Depaulis
- Grenoble Institut Neurosciences (GIN), Grenoble Alpes University, Inserm, U1216, Grenoble, France
| | - Florence Fauvelle
- Grenoble Institut Neurosciences (GIN), Grenoble Alpes University, Inserm, U1216, Grenoble, France.,Grenoble Alpes University Hospital Center, Grenoble Alpes University, Inserm, US17, CNRS, UMS 3552, IRMaGe, Grenoble, France
| |
Collapse
|
24
|
Asaki Y, Murofushi Y, Yasukawa K, Hara M, Takanashi JI. Neurochemistry of hyponatremic encephalopathy evaluated by MR spectroscopy. Brain Dev 2020; 42:767-770. [PMID: 32718672 DOI: 10.1016/j.braindev.2020.07.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Revised: 07/06/2020] [Accepted: 07/07/2020] [Indexed: 02/07/2023]
Abstract
MR spectroscopy in a patient with hyponatremic encephalopathy due to the syndrome of inappropriate secretion of antidiuretic hormone revealed decreased N-acetyl-aspartate, creatine plus phosphocreatine, choline-containing compounds, and myo-inositol, with normal glutamate and increased glutamine, which normalized after Na normalization. The decreased concentrations of creatine plus phosphocreatine, choline-containing compounds and myo-inositol are explained by their release as osmolytes from brain cells to adapt to hypo-osmolality induced cerebral edema. Increased glutamine, which not only acts as an osmolyte but also protects neurons under excitotoxic conditions, may suggest that a disrupted glutamate-glutamine cycle may play an important role in the pathogenesis of hyponatremic encephalopathy.
Collapse
Affiliation(s)
- Yumie Asaki
- Department of Pediatrics, Tokyo Women's Medical University Yachiyo Medical Center, Chiba, Japan
| | - Yuka Murofushi
- Department of Pediatrics, Tokyo Women's Medical University Yachiyo Medical Center, Chiba, Japan
| | - Kumi Yasukawa
- Department of Pediatrics, Tokyo Women's Medical University Yachiyo Medical Center, Chiba, Japan
| | - Mayumi Hara
- Department of Pediatrics, Tokyo Women's Medical University Yachiyo Medical Center, Chiba, Japan
| | - Jun-Ichi Takanashi
- Department of Pediatrics, Tokyo Women's Medical University Yachiyo Medical Center, Chiba, Japan.
| |
Collapse
|
25
|
Stevenson R, Samokhina E, Rossetti I, Morley JW, Buskila Y. Neuromodulation of Glial Function During Neurodegeneration. Front Cell Neurosci 2020; 14:278. [PMID: 32973460 PMCID: PMC7473408 DOI: 10.3389/fncel.2020.00278] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Accepted: 08/05/2020] [Indexed: 12/12/2022] Open
Abstract
Glia, a non-excitable cell type once considered merely as the connective tissue between neurons, is nowadays acknowledged for its essential contribution to multiple physiological processes including learning, memory formation, excitability, synaptic plasticity, ion homeostasis, and energy metabolism. Moreover, as glia are key players in the brain immune system and provide structural and nutritional support for neurons, they are intimately involved in multiple neurological disorders. Recent advances have demonstrated that glial cells, specifically microglia and astroglia, are involved in several neurodegenerative diseases including Amyotrophic lateral sclerosis (ALS), Epilepsy, Parkinson's disease (PD), Alzheimer's disease (AD), and frontotemporal dementia (FTD). While there is compelling evidence for glial modulation of synaptic formation and regulation that affect neuronal signal processing and activity, in this manuscript we will review recent findings on neuronal activity that affect glial function, specifically during neurodegenerative disorders. We will discuss the nature of each glial malfunction, its specificity to each disorder, overall contribution to the disease progression and assess its potential as a future therapeutic target.
Collapse
Affiliation(s)
- Rebecca Stevenson
- School of Medicine, Western Sydney University, Campbelltown, NSW, Australia
| | - Evgeniia Samokhina
- School of Medicine, Western Sydney University, Campbelltown, NSW, Australia
| | - Ilaria Rossetti
- School of Medicine, Western Sydney University, Campbelltown, NSW, Australia
| | - John W. Morley
- School of Medicine, Western Sydney University, Campbelltown, NSW, Australia
| | - Yossi Buskila
- School of Medicine, Western Sydney University, Campbelltown, NSW, Australia
- International Centre for Neuromorphic Systems, The MARCS Institute for Brain, Behaviour and Development, Penrith, NSW, Australia
| |
Collapse
|
26
|
Frieg B, Görg B, Qvartskhava N, Jeitner T, Homeyer N, Häussinger D, Gohlke H. Mechanism of Fully Reversible, pH-Sensitive Inhibition of Human Glutamine Synthetase by Tyrosine Nitration. J Chem Theory Comput 2020; 16:4694-4705. [PMID: 32551588 DOI: 10.1021/acs.jctc.0c00249] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Glutamine synthetase (GS) catalyzes an ATP-dependent condensation of glutamate and ammonia to form glutamine. This reaction-and therefore GS-are indispensable for the hepatic nitrogen metabolism. Nitration of tyrosine 336 (Y336) inhibits human GS activity. GS nitration and the consequent loss of GS function are associated with a broad range of neurological diseases. The mechanism by which Y336 nitration inhibits GS, however, is not understood. Here, we show by means of unbiased MD simulations, binding, and configurational free energy computations that Y336 nitration hampers ATP binding but only in the deprotonated and negatively charged state of residue 336. By contrast, for the protonated and neutral state, our computations indicate an increased binding affinity for ATP. pKa computations of nitrated Y336 within GS predict a pKa of ∼5.3. Thus, at physiological pH, nitrated Y336 exists almost exclusively in the deprotonated and negatively charged state. In vitro experiments confirm these predictions, in that, the catalytic activity of nitrated GS is decreased at pH 7 and 6 but not at pH 4. These results indicate a novel, fully reversible, pH-sensitive mechanism for the regulation of GS activity by tyrosine nitration.
Collapse
Affiliation(s)
- Benedikt Frieg
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.,John von Neumann Institute for Computing (NIC), Jülich Supercomputing Centre (JSC), and Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Boris Görg
- Clinic for Gastroenterology, Hepatology, and Infectious Diseases, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Natalia Qvartskhava
- Clinic for Gastroenterology, Hepatology, and Infectious Diseases, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Thomas Jeitner
- Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, New York 10595, United States
| | - Nadine Homeyer
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Dieter Häussinger
- Clinic for Gastroenterology, Hepatology, and Infectious Diseases, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Holger Gohlke
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.,John von Neumann Institute for Computing (NIC), Jülich Supercomputing Centre (JSC), and Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich GmbH, Jülich, Germany
| |
Collapse
|
27
|
Kundap UP, Paudel YN, Shaikh MF. Animal Models of Metabolic Epilepsy and Epilepsy Associated Metabolic Dysfunction: A Systematic Review. Pharmaceuticals (Basel) 2020; 13:ph13060106. [PMID: 32466498 PMCID: PMC7345684 DOI: 10.3390/ph13060106] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 05/22/2020] [Accepted: 05/23/2020] [Indexed: 12/13/2022] Open
Abstract
Epilepsy is a serious neurological disorder affecting around 70 million people globally and is characterized by spontaneous recurrent seizures. Recent evidence indicates that dysfunction in metabolic processes can lead to the alteration of neuronal and network excitability, thereby contributing to epileptogenesis. Developing a suitable animal model that can recapitulate all the clinical phenotypes of human metabolic epilepsy (ME) is crucial yet challenging. The specific environment of many symptoms as well as the primary state of the applicable neurobiology, genetics, and lack of valid biomarkers/diagnostic tests are the key factors that hinder the process of developing a suitable animal model. The present systematic review summarizes the current state of available animal models of metabolic dysfunction associated with epileptic disorders. A systematic search was performed by using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) model. A range of electronic databases, including google scholar, Springer, PubMed, ScienceDirect, and Scopus, were scanned between January 2000 and April 2020. Based on the selection criteria, 23 eligible articles were chosen and are discussed in the current review. Critical analysis of the selected literature delineated several available approaches that have been modeled into metabolic epilepsy and pointed out several drawbacks associated with the currently available models. The result describes available models of metabolic dysfunction associated with epileptic disorder, such as mitochondrial respiration deficits, Lafora disease (LD) model-altered glycogen metabolism, causing epilepsy, glucose transporter 1 (GLUT1) deficiency, adiponectin responsive seizures, phospholipid dysfunction, glutaric aciduria, mitochondrial disorders, pyruvate dehydrogenase (PDH) α-subunit gene (PDHA1), pyridoxine dependent epilepsy (PDE), BCL2-associated agonist of cell death (BAD), Kcna1 knock out (KO), and long noncoding RNAs (lncRNA) cancer susceptibility candidate 2 (lncRNA CASC2). Finally, the review highlights certain focus areas that may increase the possibilities of developing more suitable animal models and underscores the importance of the rationalization of animal models and evaluation methods for studying ME. The review also suggests the pressing need of developing precise robust animal models and evaluation methods for investigating ME.
Collapse
Affiliation(s)
- Uday Praful Kundap
- Research Center of the University of Montreal Hospital Center (CRCHUM), Department of Neurosciences, Université de Montréal, Montréal, QC H2X 0A9, Canada; (U.P.K.); (Y.N.P.)
- Neuropharmacology Research Strength, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Selangor 47500, Malaysia
| | - Yam Nath Paudel
- Research Center of the University of Montreal Hospital Center (CRCHUM), Department of Neurosciences, Université de Montréal, Montréal, QC H2X 0A9, Canada; (U.P.K.); (Y.N.P.)
| | - Mohd. Farooq Shaikh
- Neuropharmacology Research Strength, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Selangor 47500, Malaysia
- Correspondence: ; Tel.: +60-3-551-44-483
| |
Collapse
|
28
|
Pimentel-Silva LR, Casseb RF, Cordeiro MM, Campos BAG, Alvim MKM, Rogerio F, Yasuda CL, Cendes F. Interactions between in vivo neuronal-glial markers, side of hippocampal sclerosis, and pharmacoresponse in temporal lobe epilepsy. Epilepsia 2020; 61:1008-1018. [PMID: 32347553 DOI: 10.1111/epi.16509] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2020] [Revised: 03/01/2020] [Accepted: 03/29/2020] [Indexed: 12/01/2022]
Abstract
OBJECTIVE To evaluate the interactions of metabolic neuronal-glial changes with the presence and hemispheric-side of hippocampal sclerosis (HS) and its potential role in predicting pharmacoresistance in temporal lobe epilepsy (TLE). METHODS We included structural magnetic resonance imaging (MRI) and proton magnetic resonance spectroscopy (1 H-MRS) metabolic data for 91 patients with unilateral TLE and 50 healthy controls. We measured the values of total N-acetyl aspartate/total creatine (tNAA/tCr), glutamate/tCr (Glu/tCr), and myo-inositol/tCr (mIns/tCr). To assess the influence of the pharmacoresponse and hemispheric-side of HS on metabolic data, the relationship between clinical and MRI data, and the predictive value of NAA/Cr, we used analysis of variance/covariance and built a logistic regression model. We used bootstrap simulations to evaluate reproducibility. RESULTS Bilateral tNAA/tCr reduction was associated with pharmacoresistance and with left HS, a decrease of Glu/tCr ipsilateral to the seizure focus was associated with pharmacoresistance, and ipsilateral mIns/tCr increase was related to pharmacoresistance and the presence of left HS. The logistic regression model containing clinical and 1 H-MRS data discriminated pharmacoresistance (area under the curve [AUC] = 0.78). However, the reduction of tNAA/tCr was the main predictor, with the odds 2.48 greater for pharmacoresistance. SIGNIFICANCE Our study revealed a spectrum of neuronal-glial changes in TLE, which was associated with pharmacoresistance, being more severe in left-sided HS and less severe in MRI-negative TLE. These noninvasive, in vivo biomarkers provide valuable additional information about the interhemispheric differences in metabolic dysfunction, seizure burden, and HS, and may help to predict pharmacoresistance.
Collapse
Affiliation(s)
| | - Raphael F Casseb
- Department of Neurology, University of Campinas, Campinas, Brazil
| | | | - Bruno A G Campos
- Department of Neurology, University of Campinas, Campinas, Brazil
| | - Marina K M Alvim
- Department of Neurology, University of Campinas, Campinas, Brazil
| | - Fábio Rogerio
- Department of Pathology, University of Campinas, Campinas, Brazil
| | | | - Fernando Cendes
- Department of Neurology, University of Campinas, Campinas, Brazil
| |
Collapse
|
29
|
Abstract
Psychiatric illnesses, including depression and anxiety, are highly comorbid with epilepsy (for review see Josephson and Jetté (Int Rev Psychiatry 29:409-424, 2017), Salpekar and Mula (Epilepsy Behav 98:293-297, 2019)). Psychiatric comorbidities negatively impact the quality of life of patients (Johnson et al., Epilepsia 45:544-550, 2004; Cramer et al., Epilepsy Behav 4:515-521, 2003) and present a significant challenge to treating patients with epilepsy (Hitiris et al., Epilepsy Res 75:192-196, 2007; Petrovski et al., Neurology 75:1015-1021, 2010; Fazel et al., Lancet 382:1646-1654, 2013) (for review see Kanner (Seizure 49:79-82, 2017)). It has long been acknowledged that there is an association between psychiatric illnesses and epilepsy. Hippocrates, in the fourth-fifth century B.C., considered epilepsy and melancholia to be closely related in which he writes that "melancholics ordinarily become epileptics, and epileptics, melancholics" (Lewis, J Ment Sci 80:1-42, 1934). The Babylonians also recognized the frequency of psychosis in patients with epilepsy (Reynolds and Kinnier Wilson, Epilepsia 49:1488-1490, 2008). Despite the fact that the relationship between psychiatric comorbidities and epilepsy has been recognized for thousands of years, psychiatric illnesses in people with epilepsy still commonly go undiagnosed and untreated (Hermann et al., Epilepsia 41(Suppl 2):S31-S41, 2000) and systematic research in this area is still lacking (Devinsky, Epilepsy Behav 4(Suppl 4):S2-S10, 2003). Thus, although it is clear that these are not new issues, there is a need for improvements in the screening and management of patients with psychiatric comorbidities in epilepsy (Lopez et al., Epilepsy Behav 98:302-305, 2019) and progress is needed to understand the underlying neurobiology contributing to these comorbid conditions. To that end, this chapter will raise awareness regarding the scope of the problem as it relates to comorbid psychiatric illnesses and epilepsy and review our current understanding of the potential mechanisms contributing to these comorbidities, focusing on both basic science and clinical research findings.
Collapse
|
30
|
Dobberthien BJ, Tessier AG, Stanislaus AE, Sawyer MB, Fallone BG, Yahya A. PRESS timings for resolving 13 C 4 -glutamate 1 H signal at 9.4 T: Demonstration in rat with uniformly labelled 13 C-glucose. NMR IN BIOMEDICINE 2019; 32:e4180. [PMID: 31518031 DOI: 10.1002/nbm.4180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 07/30/2019] [Accepted: 08/18/2019] [Indexed: 06/10/2023]
Abstract
MRS of 13 C4 -labelled glutamate (13 C4 -Glu) during an infusion of a carbon-13 (13 C)-labelled substrate, such as uniformly labelled glucose ([U-13 C6 ]-Glc), provides a measure of Glc metabolism. The presented work provides a single-shot indirect 13 C detection technique to quantify the approximately 2.51 ppm 13 C4 -Glu satellite proton (1 H) peak at 9.4 T. The methodology is an optimized point-resolved spectroscopy (PRESS) sequence that minimizes signal contamination from the strongly coupled protons of N-acetylaspartate (NAA), which resonate at approximately 2.49 ppm. J-coupling evolution of protons was characterized numerically and verified experimentally. A (TE1 , TE2 ) combination of (20 ms, 106 ms) was found to be suitable for minimizing NAA signal in the 2.51 ppm 1 H 13 C4 -Glu spectral region, while retaining the 13 C4 -Glu 1 H satellite peak. The efficacy of the technique was verified on phantom solutions and on two rat brains in vivo during an infusion of [U-13 C6 ]-Glc. LCModel was employed for analysis of the in vivo spectra to quantify the 2.51 ppm 1 H 13 C4 -Glu signal to obtain Glu C4 fractional enrichment time courses during the infusions. Cramér-Rao lower bounds of about 8% were obtained for the 2.51 ppm 13 C4 -Glu 1 H satellite peak with the optimal TE combination.
Collapse
Affiliation(s)
| | - Anthony G Tessier
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada
- Department of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada
| | | | - Michael B Sawyer
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada
| | - B Gino Fallone
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada
- Department of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada
| | - Atiyah Yahya
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada
- Department of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada
| |
Collapse
|
31
|
Kuhlmann L, Lehnertz K, Richardson MP, Schelter B, Zaveri HP. Seizure prediction - ready for a new era. Nat Rev Neurol 2019; 14:618-630. [PMID: 30131521 DOI: 10.1038/s41582-018-0055-2] [Citation(s) in RCA: 191] [Impact Index Per Article: 38.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Epilepsy is a common disorder characterized by recurrent seizures. An overwhelming majority of people with epilepsy regard the unpredictability of seizures as a major issue. More than 30 years of international effort have been devoted to the prediction of seizures, aiming to remove the burden of unpredictability and to couple novel, time-specific treatment to seizure prediction technology. A highly influential review published in 2007 concluded that insufficient evidence indicated that seizures could be predicted. Since then, several advances have been made, including successful prospective seizure prediction using intracranial EEG in a small number of people in a trial of a real-time seizure prediction device. In this Review, we examine advances in the field, including EEG databases, seizure prediction competitions, the prospective trial mentioned and advances in our understanding of the mechanisms of seizures. We argue that these advances, together with statistical evaluations, set the stage for a resurgence in efforts towards the development of seizure prediction methodologies. We propose new avenues of investigation involving a synergy between mechanisms, models, data, devices and algorithms and refine the existing guidelines for the development of seizure prediction technology to instigate development of a solution that removes the burden of the unpredictability of seizures.
Collapse
Affiliation(s)
- Levin Kuhlmann
- Centre for Human Psychopharmacology, Swinburne University of Technology, Melbourne, Victoria, Australia.,Department of Medicine - St. Vincent's, The University of Melbourne, Parkville, Victoria, Australia.,Department of Biomedical Engineering, The University of Melbourne, Parkville, Victoria, Australia
| | - Klaus Lehnertz
- Department of Epileptology, University of Bonn, Bonn, Germany. .,Interdisciplinary Center for Complex Systems, University of Bonn, Bonn, Germany.
| | - Mark P Richardson
- Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Björn Schelter
- Institute for Complex Systems and Mathematical Biology, University of Aberdeen, Aberdeen, UK
| | - Hitten P Zaveri
- Department of Neurology, Yale University, New Haven, CT, USA
| |
Collapse
|
32
|
Kobylarek D, Iwanowski P, Lewandowska Z, Limphaibool N, Szafranek S, Labrzycka A, Kozubski W. Advances in the Potential Biomarkers of Epilepsy. Front Neurol 2019; 10:685. [PMID: 31312171 PMCID: PMC6614180 DOI: 10.3389/fneur.2019.00685] [Citation(s) in RCA: 75] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2019] [Accepted: 06/12/2019] [Indexed: 12/11/2022] Open
Abstract
Epilepsy is a group of chronic neurological disorders characterized by recurrent, spontaneous, and unpredictable seizures. It is one of the most common neurological disorders, affecting tens of millions of people worldwide. Comprehensive studies on epilepsy in recent decades have revealed the complexity of epileptogenesis, in which immunological processes, epigenetic modifications, and structural changes in neuronal tissues have been identified as playing a crucial role. This review discusses the recent advances in the biomarkers of epilepsy. We evaluate the possible molecular background underlying the clinical changes observed in recent studies, focusing on therapeutic investigations, and the evidence of their safety and efficacy in the human population. This article reviews the pathophysiology of epilepsy, including recent reports on the effects of oxidative stress and hypoxia, and focuses on specific biomarkers and their clinical implications, along with further perspectives in epilepsy research.
Collapse
Affiliation(s)
- Dominik Kobylarek
- Department of Neurology, Poznan University of Medical Sciences, Poznan, Poland
| | | | | | | | | | | | | |
Collapse
|
33
|
Huyghe D, Denninger AR, Voss CM, Frank P, Gao N, Brandon N, Waagepetersen HS, Ferguson AD, Pangalos M, Doig P, Moss SJ. Phosphorylation of Glutamine Synthetase on Threonine 301 Contributes to Its Inactivation During Epilepsy. Front Mol Neurosci 2019; 12:120. [PMID: 31178690 PMCID: PMC6536897 DOI: 10.3389/fnmol.2019.00120] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 04/25/2019] [Indexed: 12/16/2022] Open
Abstract
The astrocyte-specific enzyme glutamine synthetase (GS), which catalyzes the amidation of glutamate to glutamine, plays an essential role in supporting neurotransmission and in limiting NH4+ toxicity. Accordingly, deficits in GS activity contribute to epilepsy and neurodegeneration. Despite its central role in brain physiology, the mechanisms that regulate GS activity are poorly defined. Here, we demonstrate that GS is directly phosphorylated on threonine residue 301 (T301) within the enzyme’s active site by cAMP-dependent protein kinase (PKA). Phosphorylation of T301 leads to a dramatic decrease in glutamine synthesis. Enhanced T301 phosphorylation was evident in a mouse model of epilepsy, which may contribute to the decreased GS activity seen during this trauma. Thus, our results highlight a novel molecular mechanism that determines GS activity under both normal and pathological conditions.
Collapse
Affiliation(s)
- Deborah Huyghe
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, United States
| | - Andrew R Denninger
- Mechanistic Biology & Profiling, Discovery Sciences, IMED Biotech Unit, AstraZeneca, Boston, MA, United States
| | - Caroline M Voss
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Pernille Frank
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ning Gao
- Mechanistic Biology & Profiling, Discovery Sciences, IMED Biotech Unit, AstraZeneca, Boston, MA, United States
| | - Nicholas Brandon
- Neuroscience, IMED Biotech Unit, AstraZeneca, Boston, MA, United States.,AstraZeneca Tufts Laboratory for Basic and Translational Neuroscience, Boston, MA, United States
| | - Helle S Waagepetersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Andrew D Ferguson
- Structure & Biophysics, Discovery Sciences, IMED Biotech Unit, AstraZeneca, Boston, MA, United States
| | | | - Peter Doig
- Mechanistic Biology & Profiling, Discovery Sciences, IMED Biotech Unit, AstraZeneca, Boston, MA, United States
| | - Stephen J Moss
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, United States.,Department of Neuroscience, Physiology and Pharmacology, University College, London, United Kingdom
| |
Collapse
|
34
|
Harris T, Azar A, Sapir G, Gamliel A, Nardi-Schreiber A, Sosna J, Gomori JM, Katz-Brull R. Real-time ex-vivo measurement of brain metabolism using hyperpolarized [1- 13C]pyruvate. Sci Rep 2018; 8:9564. [PMID: 29934508 PMCID: PMC6014998 DOI: 10.1038/s41598-018-27747-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 06/11/2018] [Indexed: 12/19/2022] Open
Abstract
The ability to directly monitor in vivo brain metabolism in real time in a matter of seconds using the dissolution dynamic nuclear polarization technology holds promise to aid the understanding of brain physiology in health and disease. However, translating the hyperpolarized signal observed in the brain to cerebral metabolic rates is not straightforward, as the observed in vivo signals reflect also the influx of metabolites produced in the body, the cerebral blood volume, and the rate of transport across the blood brain barrier. We introduce a method to study rapid metabolism of hyperpolarized substrates in the viable rat brain slices preparation, an established ex vivo model of the brain. By retrospective evaluation of tissue motion and settling from analysis of the signal of the hyperpolarized [1-13C]pyruvate precursor, the T1s of the metabolites and their rates of production can be determined. The enzymatic rates determined here are in the range of those determined previously with classical biochemical assays and are in agreement with hyperpolarized metabolite relative signal intensities observed in the rodent brain in vivo.
Collapse
Affiliation(s)
- Talia Harris
- Department of Radiology, Hadassah-Hebrew University Medical Center, Jerusalem, 9112001, Israel
| | - Assad Azar
- Department of Radiology, Hadassah-Hebrew University Medical Center, Jerusalem, 9112001, Israel
| | - Gal Sapir
- Department of Radiology, Hadassah-Hebrew University Medical Center, Jerusalem, 9112001, Israel
| | - Ayelet Gamliel
- Department of Radiology, Hadassah-Hebrew University Medical Center, Jerusalem, 9112001, Israel
| | - Atara Nardi-Schreiber
- Department of Radiology, Hadassah-Hebrew University Medical Center, Jerusalem, 9112001, Israel
| | - Jacob Sosna
- Department of Radiology, Hadassah-Hebrew University Medical Center, Jerusalem, 9112001, Israel
| | - J Moshe Gomori
- Department of Radiology, Hadassah-Hebrew University Medical Center, Jerusalem, 9112001, Israel
| | - Rachel Katz-Brull
- Department of Radiology, Hadassah-Hebrew University Medical Center, Jerusalem, 9112001, Israel.
| |
Collapse
|
35
|
|
36
|
Flanagan B, McDaid L, Wade J, Wong-Lin K, Harkin J. A computational study of astrocytic glutamate influence on post-synaptic neuronal excitability. PLoS Comput Biol 2018; 14:e1006040. [PMID: 29659572 PMCID: PMC5919689 DOI: 10.1371/journal.pcbi.1006040] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 04/26/2018] [Accepted: 02/15/2018] [Indexed: 11/18/2022] Open
Abstract
The ability of astrocytes to rapidly clear synaptic glutamate and purposefully release the excitatory transmitter is critical in the functioning of synapses and neuronal circuits. Dysfunctions of these homeostatic functions have been implicated in the pathology of brain disorders such as mesial temporal lobe epilepsy. However, the reasons for these dysfunctions are not clear from experimental data and computational models have been developed to provide further understanding of the implications of glutamate clearance from the extracellular space, as a result of EAAT2 downregulation: although they only partially account for the glutamate clearance process. In this work, we develop an explicit model of the astrocytic glutamate transporters, providing a more complete description of the glutamate chemical potential across the astrocytic membrane and its contribution to glutamate transporter driving force based on thermodynamic principles and experimental data. Analysis of our model demonstrates that increased astrocytic glutamate content due to glutamine synthetase downregulation also results in increased postsynaptic quantal size due to gliotransmission. Moreover, the proposed model demonstrates that increased astrocytic glutamate could prolong the time course of glutamate in the synaptic cleft and enhances astrocyte-induced slow inward currents, causing a disruption to the clarity of synaptic signalling and the occurrence of intervals of higher frequency postsynaptic firing. Overall, our work distilled the necessity of a low astrocytic glutamate concentration for reliable synaptic transmission of information and the possible implications of enhanced glutamate levels as in epilepsy. The role of astrocytes in the excitability and hyperexcitability of neurons is a subject which has gained a lot of attention, particularly in the pathology of neurological disorders including epilepsy. Although not completely understood, the control of glutamate homeostasis is believed to play a role in paroxysmal neuronal hyperexcitability known to precede seizure activity. We have developed a computational model which explores two of the astrocytic homeostatic mechanisms, namely glutamate clearance and gliotransmission, and connect them with a common controlling factor, astrocytic cytoplasmic glutamate concentration. In our model simulations we demonstrate both a slower clearance rate of synaptic glutamate and enhanced astrocytic glutamate release where cytoplasmic glutamate is elevated, both of which contribute to high frequency neuronal firing and conditions for seizure generation. We also describe a viable role for astrocytes as a “high pass” filter, where astrocytic activation in the form of intracellular calcium oscillations is possible for only a certain range of presynaptic neuronal firing rates, the lower bound of the range being reduced where astrocytic glutamate is elevated. In physiological terms this perhaps indicates not only neuronal but also astrocytic glutamate-mediated excitation in the neural-astrocytic network.
Collapse
Affiliation(s)
- Bronac Flanagan
- Intelligent Systems Research Centre, University of Ulster, Magee Campus, Derry~Londonderry, Northern Ireland, United Kingdom
- * E-mail:
| | - Liam McDaid
- Intelligent Systems Research Centre, University of Ulster, Magee Campus, Derry~Londonderry, Northern Ireland, United Kingdom
| | - John Wade
- Intelligent Systems Research Centre, University of Ulster, Magee Campus, Derry~Londonderry, Northern Ireland, United Kingdom
| | - KongFatt Wong-Lin
- Intelligent Systems Research Centre, University of Ulster, Magee Campus, Derry~Londonderry, Northern Ireland, United Kingdom
| | - Jim Harkin
- Intelligent Systems Research Centre, University of Ulster, Magee Campus, Derry~Londonderry, Northern Ireland, United Kingdom
| |
Collapse
|
37
|
Ambrogini P, Albertini MC, Betti M, Galati C, Lattanzi D, Savelli D, Di Palma M, Saccomanno S, Bartolini D, Torquato P, Ruffolo G, Olivieri F, Galli F, Palma E, Minelli A, Cuppini R. Neurobiological Correlates of Alpha-Tocopherol Antiepileptogenic Effects and MicroRNA Expression Modulation in a Rat Model of Kainate-Induced Seizures. Mol Neurobiol 2018; 55:7822-7838. [PMID: 29468563 PMCID: PMC6132771 DOI: 10.1007/s12035-018-0946-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 01/31/2018] [Indexed: 12/19/2022]
Abstract
Seizure-triggered maladaptive neural plasticity and neuroinflammation occur during the latent period as a key underlying event in epilepsy chronicization. Previously, we showed that α-tocopherol (α-T) reduces hippocampal neuroglial activation and neurodegeneration in the rat model of kainic acid (KA)-induced status epilepticus (SE). These findings allowed us to postulate an antiepileptogenic potential for α-T in hippocampal excitotoxicity, in line with clinical evidence showing that α-T improves seizure control in drug-resistant patients. To explore neurobiological correlates of the α-T antiepileptogenic role, rats were injected with such vitamin during the latent period starting right after KA-induced SE, and the effects on circuitry excitability, neuroinflammation, neuronal death, and microRNA (miRNA) expression were investigated in the hippocampus. Results show that in α-T-treated epileptic rats, (1) the number of population spikes elicited by pyramidal neurons, as well as the latency to the onset of epileptiform-like network activity recover to control levels; (2) neuronal death is almost prevented; (3) down-regulation of claudin, a blood-brain barrier protein, is fully reversed; (4) neuroinflammation processes are quenched (as indicated by the decrease of TNF-α, IL-1β, GFAP, IBA-1, and increase of IL-6); (5) miR-146a, miR-124, and miR-126 expression is coherently modulated in hippocampus and serum by α-T. These findings support the potential of a timely intervention with α-T in clinical management of SE to reduce epileptogenesis, thus preventing chronic epilepsy development. In addition, we suggest that the analysis of miRNA levels in serum could provide clinicians with a tool to evaluate disease evolution and the efficacy of α-T therapy in SE.
Collapse
Affiliation(s)
- Patrizia Ambrogini
- Department of Biomolecular Sciences, Section of Physiology, University of Urbino Carlo Bo, I-61029, Urbino, Italy.
| | - Maria Cristina Albertini
- Department of Biomolecular Sciences, Section of Physiology, University of Urbino Carlo Bo, I-61029, Urbino, Italy
| | - Michele Betti
- Department of Biomolecular Sciences, Section of Physiology, University of Urbino Carlo Bo, I-61029, Urbino, Italy
| | - Claudia Galati
- Department of Biomolecular Sciences, Section of Physiology, University of Urbino Carlo Bo, I-61029, Urbino, Italy
| | - Davide Lattanzi
- Department of Biomolecular Sciences, Section of Physiology, University of Urbino Carlo Bo, I-61029, Urbino, Italy
| | - David Savelli
- Department of Biomolecular Sciences, Section of Physiology, University of Urbino Carlo Bo, I-61029, Urbino, Italy
| | - Michael Di Palma
- Department of Biomolecular Sciences, Section of Physiology, University of Urbino Carlo Bo, I-61029, Urbino, Italy
| | - Stefania Saccomanno
- Department of Gastroenterology, Marche Polytechnic University, Ancona, Italy
| | - Desirée Bartolini
- Department of Pharmaceutical Sciences, University of Perugia, Perugia, Italy
| | - Pierangelo Torquato
- Department of Pharmaceutical Sciences, University of Perugia, Perugia, Italy
| | - Gabriele Ruffolo
- Department of Physiology and Pharmacology, University of Rome Sapienza, Rome, Italy
| | - Fabiola Olivieri
- Department of Molecular and Clinical Sciences, Marche Polytechnic University, Ancona, Italy.,Center of Clinical Pathology and Innovative Therapy, INRCA-IRCCS, Ancona, Italy
| | - Francesco Galli
- Department of Pharmaceutical Sciences, University of Perugia, Perugia, Italy
| | - Eleonora Palma
- Department of Physiology and Pharmacology, University of Rome Sapienza, Rome, Italy
| | - Andrea Minelli
- Department of Biomolecular Sciences, Section of Physiology, University of Urbino Carlo Bo, I-61029, Urbino, Italy
| | - Riccardo Cuppini
- Department of Biomolecular Sciences, Section of Physiology, University of Urbino Carlo Bo, I-61029, Urbino, Italy
| |
Collapse
|
38
|
Detour J, Bund C, Behr C, Cebula H, Cicek EA, Valenti-Hirsch MP, Lannes B, Lhermitte B, Nehlig A, Kehrli P, Proust F, Hirsch E, Namer IJ. Metabolomic characterization of human hippocampus from drug-resistant epilepsy with mesial temporal seizure. Epilepsia 2018; 59:607-616. [DOI: 10.1111/epi.14000] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/13/2017] [Indexed: 12/27/2022]
Affiliation(s)
- Julien Detour
- Department of Biophysics and Nuclear Medicine; University Hospitals of Strasbourg; Strasbourg France
- Department of Pharmacy; University Hospitals of Strasbourg; Strasbourg France
| | - Caroline Bund
- Department of Biophysics and Nuclear Medicine; University Hospitals of Strasbourg; Strasbourg France
- ICube; University of Strasbourg/CNRS UMR7357; Strasbourg France
| | - Charles Behr
- University Hospital of INSERM U 964; Strasbourg France
| | - Hélène Cebula
- Department of Neurosurgery; University Hospitals of Strasbourg; Strasbourg France
| | - Ercument A. Cicek
- Department of Computer Engineering; Bilkent University; Ankara Turkey
- Computational Biology Department; Carnegie Mellon University; Pittsburgh PA USA
| | | | - Béatrice Lannes
- Department of Pathology; University Hospitals of Strasbourg; Strasbourg France
| | - Benoît Lhermitte
- Department of Pathology; University Hospitals of Strasbourg; Strasbourg France
| | - Astrid Nehlig
- INSERM U1129; Paris France
- Paris Descartes University-Sorbonne Paris Cité; Paris France
- CEA; Gif sur Yvette France
| | - Pierre Kehrli
- Department of Neurosurgery; University Hospitals of Strasbourg; Strasbourg France
| | - François Proust
- Department of Neurosurgery; University Hospitals of Strasbourg; Strasbourg France
| | | | - Izzie-Jacques Namer
- Department of Biophysics and Nuclear Medicine; University Hospitals of Strasbourg; Strasbourg France
- ICube; University of Strasbourg/CNRS UMR7357; Strasbourg France
- Federation of Translational Medicine of Strasbourg (FMTS); Faculty of Medicine; University of Strasbourg; Strasbourg France
| |
Collapse
|
39
|
Bartnik-Olson BL, Ding D, Howe J, Shah A, Losey T. Glutamate metabolism in temporal lobe epilepsy as revealed by dynamic proton MRS following the infusion of [U 13-C] glucose. Epilepsy Res 2017; 136:46-53. [PMID: 28763722 DOI: 10.1016/j.eplepsyres.2017.07.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Revised: 07/04/2017] [Accepted: 07/18/2017] [Indexed: 12/27/2022]
Abstract
Focal metabolic dysfunction commonly observed in temporal lobe epilepsy (TLE), and is associated with the development of medical intractability and neurocognitive deficits. It has not been established if this dysfunction is due to cell loss or biochemical dysfunction in metabolic pathways. To explore this question, dynamic 1H MRS following an infusion of [U13- C] glucose was performed to measure glutamate (Glu) metabolism. Subjects (n=6) showed reduced Glu levels (p<0.01) in the ipsilateral mesial temporal lobe (MTL) compared with controls (n=4). However, the rate of 13C incorporation into Glu did not differ between those with epilepsy and controls (p=0.77). This suggests that reduced Glu concentrations in the region of the seizure focus are not due to disruptions in metabolic pathways, but may instead be due to neuronal loss or simplification.
Collapse
Affiliation(s)
| | - Daniel Ding
- School of Medicine, Loma Linda University, Loma Linda CA, United States
| | - John Howe
- School of Medicine, Loma Linda University, Loma Linda CA, United States
| | - Amul Shah
- School of Medicine, Loma Linda University, Loma Linda CA, United States
| | - Travis Losey
- Department of Neurology, Loma Linda University, Loma Linda CA, United States.
| |
Collapse
|
40
|
Kanamori K. Faster flux of neurotransmitter glutamate during seizure - Evidence from 13C-enrichment of extracellular glutamate in kainate rat model. PLoS One 2017; 12:e0174845. [PMID: 28403176 PMCID: PMC5389799 DOI: 10.1371/journal.pone.0174845] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 03/16/2017] [Indexed: 01/05/2023] Open
Abstract
The objective is to examine how the flux of neurotransmitter glutamate from neurons to the extracellular fluid, as measured by the rate of 13C enrichment of extracellular glutamate (GLUECF), changes in response to seizures in the kainate-induced rat model of temporal-lobe epilepsy. Following unilateral intrahippocampal injection of kainate, GLUECF was collected by microdialysis from the CA1/CA3 region of awake rats, in combination with EEG recording of chronic-phase recurrent seizures and intravenous infusion of [2,5-13C]glucose. The 13C enrichment of GLUECF C5 at ~ 10 picomol level was measured by gas-chromatography mass-spectrometry. The rate of 13C enrichment, expressed as the increase of the fractional enrichment/min, was 0.0029 ± 0.0001/min in frequently seizing rats (n = 4); this was significantly higher (p < 0.01) than in the control (0.00167 ± 0.0001/min; n = 6) or in rats with infrequent seizures (0.00172 ± 0.0001/min; n = 6). This result strongly suggests that the flux of the excitatory neurotransmitter from neurons to the extracellular fluid is significantly increased by frequent seizures. The extracellular [12C + 13C]glutamate concentration increased progressively in frequently seizing rats. Taken together, these results strongly suggest that the observed seizure-induced high flux of glutamate overstimulated glutamate receptors, which triggered a chain reaction of excitation in the CA3 recurrent glutamatergic networks. The rate of 13C enrichment of extracellular glutamine (GLNECF) at C5 was 0.00299 ± 0.00027/min in frequently seizing rats, which was higher (p < 0.05) than in controls (0.00227 ± 0.00008/min). For the first time in vivo, this study examined the effects of epileptic seizures on fluxes of the neurotransmitter glutamate and its precursor glutamine in the extracellular fluid of the hippocampus. The advantages, limitations and the potential for improvement of this approach for pre-clinical and clinical studies of temporal-lobe epilepsy are discussed.
Collapse
Affiliation(s)
- Keiko Kanamori
- Department of Epilepsy, Huntington Medical Research Institutes, Pasadena, California, United States of America
- * E-mail:
| |
Collapse
|
41
|
Dossi E, Vasile F, Rouach N. Human astrocytes in the diseased brain. Brain Res Bull 2017; 136:139-156. [PMID: 28212850 PMCID: PMC5766741 DOI: 10.1016/j.brainresbull.2017.02.001] [Citation(s) in RCA: 154] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 02/08/2017] [Accepted: 02/09/2017] [Indexed: 12/23/2022]
Abstract
Astrocytes are key active elements of the brain that contribute to information processing. They not only provide neurons with metabolic and structural support, but also regulate neurogenesis and brain wiring. Furthermore, astrocytes modulate synaptic activity and plasticity in part by controlling the extracellular space volume, as well as ion and neurotransmitter homeostasis. These findings, together with the discovery that human astrocytes display contrasting characteristics with their rodent counterparts, point to a role for astrocytes in higher cognitive functions. Dysfunction of astrocytes can thereby induce major alterations in neuronal functions, contributing to the pathogenesis of several brain disorders. In this review we summarize the current knowledge on the structural and functional alterations occurring in astrocytes from the human brain in pathological conditions such as epilepsy, primary tumours, Alzheimer's disease, major depressive disorder and Down syndrome. Compelling evidence thus shows that dysregulations of astrocyte functions and interplay with neurons contribute to the development and progression of various neurological diseases. Targeting astrocytes is thus a promising alternative approach that could contribute to the development of novel and effective therapies to treat brain disorders.
Collapse
Affiliation(s)
- Elena Dossi
- Neuroglial Interactions in Cerebral Physiopathology, Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, Paris, France.
| | - Flora Vasile
- Neuroglial Interactions in Cerebral Physiopathology, Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, Paris, France.
| | - Nathalie Rouach
- Neuroglial Interactions in Cerebral Physiopathology, Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, Paris, France.
| |
Collapse
|
42
|
Davis KA, Nanga RPR, Das S, Chen SH, Hadar PN, Pollard JR, Lucas TH, Shinohara RT, Litt B, Hariharan H, Elliott MA, Detre JA, Reddy R. Glutamate imaging (GluCEST) lateralizes epileptic foci in nonlesional temporal lobe epilepsy. Sci Transl Med 2016; 7:309ra161. [PMID: 26468323 DOI: 10.1126/scitranslmed.aaa7095] [Citation(s) in RCA: 142] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
When neuroimaging reveals a brain lesion, drug-resistant epilepsy patients show better outcomes after resective surgery than do the one-third of drug-resistant epilepsy patients who have normal brain magnetic resonance imaging (MRI). We applied a glutamate imaging method, GluCEST (glutamate chemical exchange saturation transfer), to patients with nonlesional temporal lobe epilepsy based on conventional MRI. GluCEST correctly lateralized the temporal lobe seizure focus on visual and quantitative analyses in all patients. MR spectra, available for a subset of patients and controls, corroborated the GluCEST findings. Hippocampal volumes were not significantly different between hemispheres. GluCEST allowed high-resolution functional imaging of brain glutamate and has potential to identify the epileptic focus in patients previously deemed nonlesional. This method may lead to improved clinical outcomes for temporal lobe epilepsy as well as other localization-related epilepsies.
Collapse
Affiliation(s)
- Kathryn Adamiak Davis
- Penn Epilepsy Center, Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Ravi Prakash Reddy Nanga
- Center for Magnetic Resonance & Optical Imaging, Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Sandhitsu Das
- Penn Image Computing & Science Lab, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Stephanie H Chen
- Penn Epilepsy Center, Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Peter N Hadar
- Penn Epilepsy Center, Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - John R Pollard
- Penn Epilepsy Center, Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Timothy H Lucas
- Department of Neurosurgery, Hospital of the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Russell T Shinohara
- Department of Biostatistics and Epidemiology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Brian Litt
- Penn Epilepsy Center, Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Hari Hariharan
- Center for Magnetic Resonance & Optical Imaging, Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Mark A Elliott
- Center for Magnetic Resonance & Optical Imaging, Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - John A Detre
- Center for Magnetic Resonance & Optical Imaging, Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Ravinder Reddy
- Center for Magnetic Resonance & Optical Imaging, Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104, USA
| |
Collapse
|
43
|
Valette J, Tiret B, Boumezbeur F. Experimental strategies for in vivo 13C NMR spectroscopy. Anal Biochem 2016; 529:216-228. [PMID: 27515993 DOI: 10.1016/j.ab.2016.08.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 05/24/2016] [Accepted: 08/04/2016] [Indexed: 11/15/2022]
Abstract
In vivo carbon-13 (13C) MRS opens unique insights into the metabolism of intact organisms, and has led to major advancements in the understanding of cellular metabolism under normal and pathological conditions in various organs such as skeletal muscles, the heart, the liver and the brain. However, the technique comes at the expense of significant experimental difficulties. In this review we focus on the experimental aspects of non-hyperpolarized 13C MRS in vivo. Some of the enrichment strategies which have been proposed so far are described; the various MRS acquisition paradigms to measure 13C labeling are then presented. Finally, practical aspects of 13C spectral quantification are discussed.
Collapse
Affiliation(s)
- Julien Valette
- Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Direction de la Recherche Fondamentale (DRF), Institut d'Imagerie Biomédicale (I2BM), MIRCen, F-92260 Fontenay-aux-Roses, France; Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud, Université Paris-Saclay, UMR 9199, Neurodegenerative Diseases Laboratory, F-92260 Fontenay-aux-Roses, France.
| | - Brice Tiret
- Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Direction de la Recherche Fondamentale (DRF), Institut d'Imagerie Biomédicale (I2BM), MIRCen, F-92260 Fontenay-aux-Roses, France; Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud, Université Paris-Saclay, UMR 9199, Neurodegenerative Diseases Laboratory, F-92260 Fontenay-aux-Roses, France
| | - Fawzi Boumezbeur
- Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Direction de la Recherche Fondamentale (DRF), Institut d'Imagerie Biomédicale (I2BM), NeuroSpin, F-91190 Gif-sur-Yvette, France
| |
Collapse
|
44
|
Goryawala MZ, Sheriff S, Maudsley AA. Regional distributions of brain glutamate and glutamine in normal subjects. NMR IN BIOMEDICINE 2016; 29:1108-16. [PMID: 27351339 PMCID: PMC4962701 DOI: 10.1002/nbm.3575] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 05/19/2016] [Accepted: 05/20/2016] [Indexed: 05/06/2023]
Abstract
Glutamate (Glu) and glutamine (Gln) play an important role in neuronal regulation and are of value as MRS-observable diagnostic biomarkers. In this study the relative concentrations of these metabolites have been measured in multiple regions in the normal brain using a short-TE whole-brain MRSI measurement at 3 T combined with a modified data analysis approach that used spatial averaging to obtain high-SNR spectra from atlas-registered anatomic regions or interest. By spectral fitting of high-SNR spectra this approach yielded reliable measurements across a wide volume of the brain. Spectral averaging also demonstrated increased SNR and improved fitting accuracy for the sum of Glu and Gln (Glx) compared with individual voxel fitting. Results in 26 healthy controls showed relatively constant Glu/Cr and Gln/Cr throughout the cerebrum, although with increased values in the anterior cingulum and paracentral lobule, and increased Gln/Cr in the superior motor area. The deep gray-matter regions of thalamus, putamen, and pallidum show lower Glu/Cr compared with cortical white-matter regions. Lobar measurements demonstrated reduced Glu/Cr and Gln/Cr in the cerebellum as compared with the cerebrum, where white-matter regions show significantly lower Glu/Cr and Gln/Cr as compared with gray-matter regions across multiple brain lobes. Regression analysis showed no significant effect of gender on Glu/Cr or Gln/Cr measurement; however, Glx/Cr ratio was found to be significantly negatively correlated with age in some lobar brain regions. In summary, this methodology provides the spectral quality necessary for reliable separation of Glu and Gln at 3 T from a single MRSI acquisition enabling generation of regional distributions of metabolites over a large volume of the brain, including cortical regions. Copyright © 2016 John Wiley & Sons, Ltd.
Collapse
|
45
|
Hanson E, Danbolt NC, Dulla CG. Astrocyte membrane properties are altered in a rat model of developmental cortical malformation but single-cell astrocytic glutamate uptake is robust. Neurobiol Dis 2016; 89:157-68. [PMID: 26875663 PMCID: PMC4794447 DOI: 10.1016/j.nbd.2016.02.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 02/03/2016] [Accepted: 02/09/2016] [Indexed: 12/31/2022] Open
Abstract
Developmental cortical malformations (DCMs) are linked with severe epilepsy and are caused by both genetic and environmental insults. DCMs include several neurological diseases, such as focal cortical dysplasia, polymicrogyria, schizencephaly, and others. Human studies have implicated astrocyte reactivity and dysfunction in the pathophysiology of DCMs, but their specific role is unknown. As astrocytes powerfully regulate glutamate neurotransmission, and glutamate levels are known to be increased in human epileptic foci, understanding the role of astrocytes in the pathological sequelae of DCMs is extremely important. Additionally, recent studies examining astrocyte glutamate uptake in DCMs have reported conflicting results, adding confusion to the field. In this study we utilized the freeze lesion (FL) model of DCM, which is known to induce reactive astrocytosis and cause significant changes in astrocyte morphology, proliferation, and distribution. Using whole-cell patch clamp recording from astrocytes, we recorded both UV-uncaging and synaptically evoked glutamate transporter currents (TCs), widely accepted assays of functional glutamate transport by astrocytes. With this approach, we set out to test the hypothesis that astrocyte membrane properties and glutamate transport were disrupted in this model of DCM. Though we found that the developmental maturation of astrocyte membrane resistance was disrupted by FL, glutamate uptake by individual astrocytes was robust throughout FL development. Interestingly, using an immunolabeling approach, we observed spatial and developmental differences in excitatory amino acid transporter (EAAT) expression in FL cortex. Spatially specific differences in EAAT2 (GLT-1) and EAAT1 (GLAST) expression suggest that the relative contribution of each EAAT to astrocytic glutamate uptake may be altered in FL cortex. Lastly, we carefully analyzed the amplitudes and onset times of both synaptically- and UV uncaging-evoked TCs. We found that in the FL cortex, synaptically-evoked, but not UV uncaging-evoked TCs, were larger in amplitude. Additionally, we found that the amount of electrical stimulation required to evoke a synaptic TC was significantly reduced in the FL cortex. Both of these findings are consistent with increased excitatory input to the FL cortex, but not with changes in how individual astrocytes remove glutamate. Taken together, our results demonstrate that the maturation of astrocyte membrane resistance, local distribution of glutamate transporters, and glutamatergic input to the cortex are altered in the FL model, but that single-cell astrocytic glutamate uptake is robust.
Collapse
Affiliation(s)
- Elizabeth Hanson
- Department of Neuroscience, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111, USA; Neuroscience Program, Tufts Sackler School of Biomedical Sciences, 136 Harrison Avenue, Boston, MA 02111, USA
| | - Niels Christian Danbolt
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, P.O. Box 1105 Blindern, N-0317 Oslo, Norway
| | - Chris G Dulla
- Department of Neuroscience, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111, USA; Neuroscience Program, Tufts Sackler School of Biomedical Sciences, 136 Harrison Avenue, Boston, MA 02111, USA
| |
Collapse
|
46
|
Dallérac G, Rouach N. Astrocytes as new targets to improve cognitive functions. Prog Neurobiol 2016; 144:48-67. [PMID: 26969413 DOI: 10.1016/j.pneurobio.2016.01.003] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Revised: 01/07/2016] [Accepted: 01/24/2016] [Indexed: 01/09/2023]
Abstract
Astrocytes are now viewed as key elements of brain wiring as well as neuronal communication. Indeed, they not only bridge the gap between metabolic supplies by blood vessels and neurons, but also allow fine control of neurotransmission by providing appropriate signaling molecules and insulation through a tight enwrapping of synapses. Recognition that astroglia is essential to neuronal communication is nevertheless fairly recent and the large body of evidence dissecting such role has focused on the synaptic level by identifying neuro- and gliotransmitters uptaken and released at synaptic or extrasynaptic sites. Yet, more integrated research deciphering the impact of astroglial functions on neuronal network activity have led to the reasonable assumption that the role of astrocytes in supervising synaptic activity translates in influencing neuronal processing and cognitive functions. Several investigations using recent genetic tools now support this notion by showing that inactivating or boosting astroglial function directly affects cognitive abilities. Accordingly, brain diseases resulting in impaired cognitive functions have seen their physiopathological mechanisms revisited in light of this primary protagonist of brain processing. We here provide a review of the current knowledge on the role of astrocytes in cognition and in several brain diseases including neurodegenerative disorders, psychiatric illnesses, as well as other conditions such as epilepsy. Potential astroglial therapeutic targets are also discussed.
Collapse
Affiliation(s)
- Glenn Dallérac
- Neuroglial Interactions in Cerebral Physiopathology, Center for Interdisciplinary Research in Biology, Collège de France, Centre National de la Recherche Scientifique UMR 7241, Institut National de la Santé et de la Recherche Médicale U1050, Labex Memolife, PSL Research University, Paris, France.
| | - Nathalie Rouach
- Neuroglial Interactions in Cerebral Physiopathology, Center for Interdisciplinary Research in Biology, Collège de France, Centre National de la Recherche Scientifique UMR 7241, Institut National de la Santé et de la Recherche Médicale U1050, Labex Memolife, PSL Research University, Paris, France.
| |
Collapse
|
47
|
Münster-Wandowski A, Zander JF, Richter K, Ahnert-Hilger G. Co-existence of Functionally Different Vesicular Neurotransmitter Transporters. Front Synaptic Neurosci 2016; 8:4. [PMID: 26909036 PMCID: PMC4754932 DOI: 10.3389/fnsyn.2016.00004] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 02/01/2016] [Indexed: 01/25/2023] Open
Abstract
The vesicular transmitter transporters VGLUT, VGAT, VMAT2 and VAChT, define phenotype and physiological properties of neuronal subtypes. VGLUTs concentrate the excitatory amino acid glutamate, VGAT the inhibitory amino acid GABA, VMAT2 monoamines, and VAChT acetylcholine (ACh) into synaptic vesicle (SV). Following membrane depolarization SV release their content into the synaptic cleft. A strict segregation of vesicular transporters is mandatory for the precise functioning of synaptic communication and of neuronal circuits. In the last years, evidence accumulates that subsets of neurons express more than one of these transporters leading to synaptic co-release of different and functionally opposing transmitters and modulation of synaptic plasticity. Synaptic co-existence of transporters may change during pathological scenarios in order to ameliorate misbalances in neuronal activity. In addition, evidence increases that transporters also co-exist on the same vesicle providing another layer of regulation. Generally, vesicular transmitter loading relies on an electrochemical gradient ΔμH+ driven by the proton ATPase rendering the lumen of the vesicle with respect to the cytosol positive (Δψ) and acidic (ΔpH). While the activity of VGLUT mainly depends on the Δψ component, VMAT, VGAT and VAChT work best at a high ΔpH. Thus, a vesicular synergy of transporters depending on the combination may increase or decrease the filling of SV with the principal transmitter. We provide an overview on synaptic co-existence of vesicular transmitter transporters including changes in the excitatory/inhibitory balance under pathological conditions. Additionally, we discuss functional aspects of vesicular synergy of transmitter transporters.
Collapse
Affiliation(s)
| | | | - Karin Richter
- Institute of Integrative Neuroanatomy, Charité-Universitätsmedizin Berlin Berlin, Germany
| | - Gudrun Ahnert-Hilger
- Institute of Integrative Neuroanatomy, Charité-Universitätsmedizin Berlin Berlin, Germany
| |
Collapse
|
48
|
Frieg B, Görg B, Homeyer N, Keitel V, Häussinger D, Gohlke H. Molecular Mechanisms of Glutamine Synthetase Mutations that Lead to Clinically Relevant Pathologies. PLoS Comput Biol 2016; 12:e1004693. [PMID: 26836257 PMCID: PMC4737493 DOI: 10.1371/journal.pcbi.1004693] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Accepted: 12/03/2015] [Indexed: 12/15/2022] Open
Abstract
Glutamine synthetase (GS) catalyzes ATP-dependent ligation of ammonia and glutamate to glutamine. Two mutations of human GS (R324C and R341C) were connected to congenital glutamine deficiency with severe brain malformations resulting in neonatal death. Another GS mutation (R324S) was identified in a neurologically compromised patient. However, the molecular mechanisms underlying the impairment of GS activity by these mutations have remained elusive. Molecular dynamics simulations, free energy calculations, and rigidity analyses suggest that all three mutations influence the first step of GS catalytic cycle. The R324S and R324C mutations deteriorate GS catalytic activity due to loss of direct interactions with ATP. As to R324S, indirect, water-mediated interactions reduce this effect, which may explain the suggested higher GS residual activity. The R341C mutation weakens ATP binding by destabilizing the interacting residue R340 in the apo state of GS. Additionally, the mutation is predicted to result in a significant destabilization of helix H8, which should negatively affect glutamate binding. This prediction was tested in HEK293 cells overexpressing GS by dot-blot analysis: Structural stability of H8 was impaired through mutation of amino acids interacting with R341, as indicated by a loss of masking of an epitope in the glutamate binding pocket for a monoclonal anti-GS antibody by L-methionine-S-sulfoximine; in contrast, cells transfected with wild type GS showed the masking. Our analyses reveal complex molecular effects underlying impaired GS catalytic activity in three clinically relevant mutants. Our findings could stimulate the development of ATP binding-enhancing molecules by which the R324S mutant can be repaired extrinsically. Glutamine synthetase (GS) catalyzes the ATP-dependent ligation of ammonia and glutamate to glutamine, which makes the enzyme essential for human nitrogen metabolism. Three mutations in human GS, R324C, R324S, and R341C, had been identified previously that lead to a glutamine deficiency, resulting in neonatal death in the case of R324C and R341C. However, the molecular mechanisms underlying this impairment of GS activity have remained elusive. Our results from computational biophysics approaches suggest that all three mutants influence the first step of GS’ catalytic cycle, namely ATP or glutamate binding. The analyses reveal a complex set of effects including the loss of direct interactions to substrates, the involvement of water-mediated interactions that alleviate part of the mutation effect, and long-range effects between the catalytic site and structural parts distant from it. As to the latter, experimental validation is in line with our prediction of a significant destabilization of helix H8 in the R341C mutant, which should negatively affect glutamate binding. Finally, our findings could stimulate the development of ATP-binding enhancing molecules for the R324S mutant, which has been suggested to have residual activity, that way extrinsically “repairing” the mutant.
Collapse
Affiliation(s)
- Benedikt Frieg
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich-Heine-University, Düsseldorf, Germany
| | - Boris Görg
- Clinic for Gastroenterology, Hepatology, and Infectious Diseases, Heinrich-Heine-University, Düsseldorf, Germany
| | - Nadine Homeyer
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich-Heine-University, Düsseldorf, Germany
| | - Verena Keitel
- Clinic for Gastroenterology, Hepatology, and Infectious Diseases, Heinrich-Heine-University, Düsseldorf, Germany
| | - Dieter Häussinger
- Clinic for Gastroenterology, Hepatology, and Infectious Diseases, Heinrich-Heine-University, Düsseldorf, Germany
- * E-mail: (DH); (HG)
| | - Holger Gohlke
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich-Heine-University, Düsseldorf, Germany
- * E-mail: (DH); (HG)
| |
Collapse
|
49
|
Yu Y, Xie W, Wang C. Chaihushugan decoction exerts antiepileptic effects by increasing hippocampal glutamate metabolism in pentylenetetrazole-kindled rats. J TRADIT CHIN MED 2016; 35:659-65. [PMID: 26742311 DOI: 10.1016/s0254-6272(15)30156-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
OBJECTIVE To investigate the antiepileptic effects of Chaihushugan decoction (CHSGD) in rats with pentylenetetrazole (PTZ)-induced seizures and to discuss the impact of CHSGD on glutamate metabolism, a hypothesized underlying mechanism of seizure reduction. METHODS Fifty Wistar rats were divided randomly into either control (n = 10) or experimental (n = 40) groups. Rats in the control group were administered physiological saline intraperitoneally. A subconvulsive dose of PTZ (35 mg/kg) was administered intraperitoneally to rats in the experimental group to induce seizures. The fully PTZ-kindled rats were then randomly divided into five subgroups (n = 8 each) based on the following treatment categories: physiological saline, VPA (200 mg/kg), CHSGD (2.5 g/kg), CHSGD (5 g/kg), or CHSGD (10 g/kg), administered orally once per day, respectively. On day 28 following initiation of drug treatment, seizures were monitored. The rats were then sacrificed, and hippocampal dissections were performed for subsequent studies. RESULTS CHSGD significantly prolonged the latency of myoclonic, clonic, and tonic seizures, while decreasing overall seizure rates in the kindled rats. The measured concentrations of 2-[N-(7-nitrobenz-2-oxa-1,3-diazo-4-yl) amino]-2-deoxy-d-glucose (2-NBDG) and glutamate were significantly lower in the hippocampi of kindled rats in groups treated with CHSGD compared with those treated with PTZ alone. In addition, CHSGD was found to up-regulate both the expression of glutamate transporter-1 (GLT-1) protein and the activity of glutamine synthetase (GS) in the hippocampi of kindled rats. CONCLUSION These results suggest that CHSGD has antiepileptic effects on PTZ-induced seizures. The results further suggest an increase in glutamate metabolism at the synaptic cleft is a putative underlying mechanism of seizure reduction.
Collapse
|
50
|
Peña-Ortega F, Rivera-Angulo AJ, Lorea-Hernández JJ. Pharmacological Tools to Study the Role of Astrocytes in Neural Network Functions. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 949:47-66. [DOI: 10.1007/978-3-319-40764-7_3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
|