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Huang YT, Huang TH, Chen YS, Li YJ, Huang CW. Role of α-amino-3‑hydroxy-5-methyl-4-isoxazolepropionic acid receptors and the antagonist perampanel in geriatric epilepsy and status epilepticus. Arch Gerontol Geriatr 2024; 128:105605. [PMID: 39213748 DOI: 10.1016/j.archger.2024.105605] [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: 04/28/2024] [Revised: 07/30/2024] [Accepted: 08/22/2024] [Indexed: 09/04/2024]
Abstract
The α-amino-3‑hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) is an ionotropic glutamate receptor recognized for its active involvement in epilepsy. Through AMPAR functional alterations, multiple factors contribute to the increased susceptibility to seizures in the geriatric population. These factors include changes in the hippocampus, neuroinflammation, ischemic insults, amyloid deposition, previous seizures, alterations in the microenvironment, and neurovascular unit dysfunction. Perampanel, a noncompetitive AMPAR antagonist, has been approved for the treatment of focal and generalized epilepsy. However, a complete understanding of AMPAR's role in epileptogenesis and the pharmacotherapy of perampanel in the geriatric population remains elusive. To address this gap, we conducted a comprehensive literature review, screening 1557 articles and ultimately selecting 94 relevant ones. We provided insights into AMPAR functionality changes and perampanel's role in treating geriatric epilepsy. Various clinical trials and retrospective studies have demonstrated that the safety and efficacy of perampanel in the older population are comparable to those in the younger population, with overall good tolerability. It is also effective for treating focal and generalized onset seizures and possibly for managing status epilepticus. In conclusion, the existing body of evidence supports the safety and efficacy of perampanel in the geriatric population, indicating its potential as a valuable therapeutic option for focal and generalized epilepsy. Additional research is warranted to deepen our understanding of AMPAR's involvement in epileptogenesis and to refine the pharmacotherapeutic nuances in this specific demographic.
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Affiliation(s)
- Yi-Te Huang
- Department of Geriatrics and Gerontology, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Tzu-Hsin Huang
- Zhengxin Neurology & Rehabilitation Center, Tainan, Taiwan
| | - Yu-Shiue Chen
- Department of Neurology, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, 138 Sheng-Li Rd, Tainan 70428, Taiwan
| | - Ya-Jhen Li
- Kun-Yen Medical Library, National Cheng Kung University, Tainan, Taiwan
| | - Chin-Wei Huang
- Department of Neurology, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, 138 Sheng-Li Rd, Tainan 70428, Taiwan.
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2
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Vicente M, Addo-Osafo K, Vossel K. Latest advances in mechanisms of epileptic activity in Alzheimer's disease and dementia with Lewy Bodies. Front Neurol 2024; 15:1277613. [PMID: 38390593 PMCID: PMC10882721 DOI: 10.3389/fneur.2024.1277613] [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: 08/14/2023] [Accepted: 01/12/2024] [Indexed: 02/24/2024] Open
Abstract
Alzheimer's disease (AD) and dementia with Lewy bodies (DLB) stand as the prevailing sources of neurodegenerative dementia, impacting over 55 million individuals across the globe. Patients with AD and DLB exhibit a higher prevalence of epileptic activity compared to those with other forms of dementia. Seizures can accompany AD and DLB in early stages, and the associated epileptic activity can contribute to cognitive symptoms and exacerbate cognitive decline. Aberrant neuronal activity in AD and DLB may be caused by several mechanisms that are not yet understood. Hyperexcitability could be a biomarker for early detection of AD or DLB before the onset of dementia. In this review, we compare and contrast mechanisms of network hyperexcitability in AD and DLB. We examine the contributions of genetic risk factors, Ca2+ dysregulation, glutamate, AMPA and NMDA receptors, mTOR, pathological amyloid beta, tau and α-synuclein, altered microglial and astrocytic activity, and impaired inhibitory interneuron function. By gaining a deeper understanding of the molecular mechanisms that cause neuronal hyperexcitability, we might uncover therapeutic approaches to effectively ease symptoms and slow down the advancement of AD and DLB.
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Affiliation(s)
- Mariane Vicente
- Mary S. Easton Center for Alzheimer's Research and Care, Department of Neurology, David Geffen School of Medicine at University of California, Los Angeles, CA, United States
| | - Kwaku Addo-Osafo
- Mary S. Easton Center for Alzheimer's Research and Care, Department of Neurology, David Geffen School of Medicine at University of California, Los Angeles, CA, United States
| | - Keith Vossel
- Mary S. Easton Center for Alzheimer's Research and Care, Department of Neurology, David Geffen School of Medicine at University of California, Los Angeles, CA, United States
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3
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Modarres Mousavi SM, Alipour F, Noorbakhsh F, Jafarian M, Ghadipasha M, Gharehdaghi J, Kellinghaus C, Speckmann EJ, Stummer W, Khaleghi Ghadiri M, Gorji A. Clinical Correlation of Altered Molecular Signatures in Epileptic Human Hippocampus and Amygdala. Mol Neurobiol 2024; 61:725-752. [PMID: 37658249 PMCID: PMC10861640 DOI: 10.1007/s12035-023-03583-6] [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: 12/26/2022] [Accepted: 08/14/2023] [Indexed: 09/03/2023]
Abstract
Widespread alterations in the expression of various genes could contribute to the pathogenesis of epilepsy. The expression levels of various genes, including major inhibitory and excitatory receptors, ion channels, cell type-specific markers, and excitatory amino acid transporters, were assessed and compared between the human epileptic hippocampus and amygdala, and findings from autopsy controls. Moreover, the potential correlation between molecular alterations in epileptic brain tissues and the clinical characteristics of patients undergoing epilepsy surgery was evaluated. Our findings revealed significant and complex changes in the expression of several key regulatory genes in both the hippocampus and amygdala of patients with intractable epilepsy. The expression changes in various genes differed considerably between the epileptic hippocampus and amygdala. Different correlation patterns were observed between changes in gene expression and clinical characteristics, depending on whether the patients were considered as a whole or were subdivided. Altered molecular signatures in different groups of epileptic patients, defined within a given category, could be viewed as diagnostic biomarkers. Distinct patterns of molecular changes that distinguish these groups from each other appear to be associated with epilepsy-specific functional consequences.
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Affiliation(s)
| | - Fatemeh Alipour
- Shefa Neuroscience Research Center, Khatam Alanbia Hospital, Tehran, Iran
| | - Farshid Noorbakhsh
- Shefa Neuroscience Research Center, Khatam Alanbia Hospital, Tehran, Iran
| | - Maryam Jafarian
- Shefa Neuroscience Research Center, Khatam Alanbia Hospital, Tehran, Iran
| | - Masoud Ghadipasha
- Legal Medicine Research Center, Legal Medicine Organization, Tehran, Iran
| | - Jaber Gharehdaghi
- Legal Medicine Research Center, Legal Medicine Organization, Tehran, Iran
| | | | - Erwin-Josef Speckmann
- Department of Neurosurgery, Westfälische Wilhelms-Universität Münster, Münster, Germany
- Epilepsy Research Center, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Walter Stummer
- Department of Neurosurgery, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | | | - Ali Gorji
- Shefa Neuroscience Research Center, Khatam Alanbia Hospital, Tehran, Iran.
- Department of Neurosurgery, Westfälische Wilhelms-Universität Münster, Münster, Germany.
- Epilepsy Research Center, Westfälische Wilhelms-Universität Münster, Münster, Germany.
- Department of Neuroscience, Mashhad University of Medical Sciences, Mashhad, Iran.
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4
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Dashtban-Moghadam E, Khodaverdian S, Dabirmanesh B, Mirnajafi-Zadeh J, Shojaei A, Mirzaie M, Choopanian P, Atabakhshi-Kashi M, Fatholahi Y, Khajeh K. Hippocampal tandem mass tag (TMT) proteomics analysis during kindling epileptogenesis in rat. Brain Res 2024; 1822:148620. [PMID: 37848119 DOI: 10.1016/j.brainres.2023.148620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2023] [Revised: 10/02/2023] [Accepted: 10/04/2023] [Indexed: 10/19/2023]
Abstract
Epilepsy is a neurological disorder that remains difficult to treat due to the lack of a clear molecular mechanism and incomplete understanding of involved proteins. To identify potential therapeutic targets, it is important to gain insight into changes in protein expression patterns related to epileptogenesis. One promising approach is to analyze proteomic data, which can provide valuable information about these changes. In this study, to evaluate the changes in gene expression during epileptogenesis, LC-MC2 analysis was carried out on hippocampus during stages of electrical kindling in rat models. Subsequently, progressive changes in the expression of proteins were detected as a result of epileptogenesis development. In line with behavioral kindled seizure stages and according to the proteomics data, we described epileptogenesis phases by comparing Stage3 versus Control (S3/C0), Stage5 versus Stage3 (S5/S3), and Stage5 versus Control group (S5/C0). Gene ontology analysis on differentially expressed proteins (DEPs) showed significant changes of proteins involved in immune responses like Csf1R, Aif1 and Stat1 during S3/C0, regulation of synaptic plasticity like Bdnf, Rac1, CaMK, Cdc42 and P38 during S5/S3, and nervous system development throughout S5/C0 like Bdnd, Kcc2 and Slc1a3.There were also proteins like Cox2, which were altered commonly among all three phases. The pathway enrichment analysis of DEPs was also done to discover molecular connections between phases and we have found that the targets like Csf1R, Bdnf and Cox2 were analyzed throughout all three phases were highly involved in the PPI network analysis as hub nodes. Additionally, these same targets underwent changes which were confirmed through Western blotting. Our results have identified proteomic patterns that could shed light on the molecular mechanisms underlying epileptogenesis which may allow for novel targeted therapeutic strategies.
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Affiliation(s)
- Elahe Dashtban-Moghadam
- Department of Biochemistry, Faculty of Biological Science, Tarbiat Modares University, Tehran, Iran
| | - Shima Khodaverdian
- Department of Biochemistry, Faculty of Biological Science, Tarbiat Modares University, Tehran, Iran
| | - Bahareh Dabirmanesh
- Department of Biochemistry, Faculty of Biological Science, Tarbiat Modares University, Tehran, Iran
| | - Javad Mirnajafi-Zadeh
- Department of Medical Physiology, Faculty of Medical Science, Tarbiat Modares University, Tehran, Iran; Institute for Brain and Cognition, Tarbiat Modares University, Tehran, Iran
| | - Amir Shojaei
- Department of Medical Physiology, Faculty of Medical Science, Tarbiat Modares University, Tehran, Iran
| | - Mehdi Mirzaie
- Department of Pharmacology, Faculty of Medicine, Neuroscience Center & Helsinki Institute of Life Science, University of Helsinki, Helsinki 00290, Finland; Department of Applied Mathematics, Faculty of Mathematical Science, Tarbiat Modares University, Tehran, Iran
| | - Peyman Choopanian
- Department of Pharmacology, Faculty of Medicine, Neuroscience Center & Helsinki Institute of Life Science, University of Helsinki, Helsinki 00290, Finland
| | - Mona Atabakhshi-Kashi
- CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, CAS Center for Nanoscience and Technology, Beijing 100190, China
| | - Yaghoub Fatholahi
- Department of Medical Physiology, Faculty of Medical Science, Tarbiat Modares University, Tehran, Iran.
| | - Khosro Khajeh
- Department of Biochemistry, Faculty of Biological Science, Tarbiat Modares University, Tehran, Iran.
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5
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Rupareliya VP, Singh AA, Butt AM, A H, Kumar H. The "molecular soldiers" of the CNS: Astrocytes, a comprehensive review on their roles and molecular signatures. Eur J Pharmacol 2023; 959:176048. [PMID: 37758010 DOI: 10.1016/j.ejphar.2023.176048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 08/24/2023] [Accepted: 09/13/2023] [Indexed: 09/29/2023]
Abstract
For a long time, neurons held the position of central players in the nervous system. Since there are far more astrocytes than neurons in the brain, it makes us wonder if these cells just take up space and support the neurons or if they are actively participating in central nervous system (CNS) homeostasis. Now, astrocytes' contribution to CNS physiology is appreciated as they are known to regulate ion and neurotransmitter levels, synapse formation and elimination, blood-brain barrier integrity, immune function, cerebral blood flow, and many more. In many neurological and psychiatric disorders, astrocyte functions are altered. Advancements in microscopic and transcriptomic tools revealed populations of astrocytes with varied morphology, electrophysiological properties, and transcriptomic profiles. Neuron-circuit-specific functions and neuron-specific interactions of astroglial subpopulations are found, which suggests that diversity is essential in carrying out diverse region-specific CNS functions. Investigations on heterogeneous astrocyte populations are revealing new astrocyte functions and their role in pathological conditions, opening a new therapeutic avenue for targeting neurological conditions. The true extent of astrocytic heterogeneity and its functional implications are yet to be fully explored. This review summarizes essential astrocytic functions and their relevance in pathological conditions and discusses astrocytic diversity in relation to morphology, function, and gene expression throughout the CNS.
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Affiliation(s)
- Vimal P Rupareliya
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER)-Ahmedabad, Gandhinagar, Gujarat 382355, India
| | - Aditya A Singh
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER)-Ahmedabad, Gandhinagar, Gujarat 382355, India
| | - Ayub Mohammed Butt
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER)-Ahmedabad, Gandhinagar, Gujarat 382355, India
| | - Hariharan A
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER)-Ahmedabad, Gandhinagar, Gujarat 382355, India
| | - Hemant Kumar
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER)-Ahmedabad, Gandhinagar, Gujarat 382355, India.
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6
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Verkhratsky A, Butt A, Li B, Illes P, Zorec R, Semyanov A, Tang Y, Sofroniew MV. Astrocytes in human central nervous system diseases: a frontier for new therapies. Signal Transduct Target Ther 2023; 8:396. [PMID: 37828019 PMCID: PMC10570367 DOI: 10.1038/s41392-023-01628-9] [Citation(s) in RCA: 43] [Impact Index Per Article: 43.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2023] [Revised: 08/15/2023] [Accepted: 08/22/2023] [Indexed: 10/14/2023] Open
Abstract
Astroglia are a broad class of neural parenchymal cells primarily dedicated to homoeostasis and defence of the central nervous system (CNS). Astroglia contribute to the pathophysiology of all neurological and neuropsychiatric disorders in ways that can be either beneficial or detrimental to disorder outcome. Pathophysiological changes in astroglia can be primary or secondary and can result in gain or loss of functions. Astroglia respond to external, non-cell autonomous signals associated with any form of CNS pathology by undergoing complex and variable changes in their structure, molecular expression, and function. In addition, internally driven, cell autonomous changes of astroglial innate properties can lead to CNS pathologies. Astroglial pathophysiology is complex, with different pathophysiological cell states and cell phenotypes that are context-specific and vary with disorder, disorder-stage, comorbidities, age, and sex. Here, we classify astroglial pathophysiology into (i) reactive astrogliosis, (ii) astroglial atrophy with loss of function, (iii) astroglial degeneration and death, and (iv) astrocytopathies characterised by aberrant forms that drive disease. We review astroglial pathophysiology across the spectrum of human CNS diseases and disorders, including neurotrauma, stroke, neuroinfection, autoimmune attack and epilepsy, as well as neurodevelopmental, neurodegenerative, metabolic and neuropsychiatric disorders. Characterising cellular and molecular mechanisms of astroglial pathophysiology represents a new frontier to identify novel therapeutic strategies.
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Affiliation(s)
- Alexei Verkhratsky
- International Joint Research Centre on Purinergic Signalling/School of Health and Rehabilitation, Chengdu University of Traditional Chinese Medicine, Chengdu, China.
- Department of Forensic Analytical Toxicology, School of Forensic Medicine, China Medical University, Shenyang, China.
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.
- Achucarro Centre for Neuroscience, IKERBASQUE, Basque Foundation for Science, Bilbao, Spain.
- Department of Stem Cell Biology, State Research Institute Centre for Innovative Medicine, LT-01102, Vilnius, Lithuania.
| | - Arthur Butt
- Institute of Biomedical and Biomolecular Sciences, School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth, UK
| | - Baoman Li
- Department of Forensic Analytical Toxicology, School of Forensic Medicine, China Medical University, Shenyang, China
| | - Peter Illes
- International Joint Research Centre on Purinergic Signalling/School of Health and Rehabilitation, Chengdu University of Traditional Chinese Medicine, Chengdu, China
- Rudolf Boehm Institute for Pharmacology and Toxicology, University of Leipzig, 04109, Leipzig, Germany
| | - Robert Zorec
- Celica Biomedical, Lab Cell Engineering, Technology Park, 1000, Ljubljana, Slovenia
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, University of Ljubljana, Faculty of Medicine, Ljubljana, Slovenia
| | - Alexey Semyanov
- Department of Physiology, Jiaxing University College of Medicine, 314033, Jiaxing, China
| | - Yong Tang
- International Joint Research Centre on Purinergic Signalling/School of Health and Rehabilitation, Chengdu University of Traditional Chinese Medicine, Chengdu, China.
- Key Laboratory of Acupuncture for Senile Disease (Chengdu University of TCM), Ministry of Education/Acupuncture and Chronobiology Key Laboratory of Sichuan Province, Chengdu, China.
| | - Michael V Sofroniew
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.
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7
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Henning L, Unichenko P, Bedner P, Steinhäuser C, Henneberger C. Overview Article Astrocytes as Initiators of Epilepsy. Neurochem Res 2023; 48:1091-1099. [PMID: 36244037 PMCID: PMC10030460 DOI: 10.1007/s11064-022-03773-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 08/22/2022] [Accepted: 09/27/2022] [Indexed: 10/17/2022]
Abstract
Astrocytes play a dual role in the brain. On the one hand, they are active signaling partners of neurons and can for instance control synaptic transmission and its plasticity. On the other hand, they fulfill various homeostatic functions such as clearance of glutamate and K+ released from neurons. The latter is for instance important for limiting neuronal excitability. Therefore, an impairment or failure of glutamate and K+ clearance will lead to increased neuronal excitability, which could trigger or aggravate brain diseases such as epilepsy, in which neuronal hyperexcitability plays a role. Experimental data indicate that astrocytes could have such a causal role in epilepsy, but the role of astrocytes as initiators of epilepsy and the relevant mechanisms are under debate. In this overview, we will discuss the potential mechanisms with focus on K+ clearance, glutamate uptake and homoeostasis and related mechanisms, and the evidence for their causative role in epilepsy.
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Affiliation(s)
- Lukas Henning
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, 53127, Bonn, Germany
| | - Petr Unichenko
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, 53127, Bonn, Germany
| | - Peter Bedner
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, 53127, Bonn, Germany
| | - Christian Steinhäuser
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, 53127, Bonn, Germany.
| | - Christian Henneberger
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, 53127, Bonn, Germany.
- German Center for Neurodegenerative Diseases (DZNE), 53127, Bonn, Germany.
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8
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Liao QQ, Dong QQ, Zhang H, Shu HP, Tu YC, Yao LJ. Contributions of SGK3 to transporter-related diseases. Front Cell Dev Biol 2022; 10:1007924. [PMID: 36531961 PMCID: PMC9753149 DOI: 10.3389/fcell.2022.1007924] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Accepted: 11/09/2022] [Indexed: 02/09/2024] Open
Abstract
Serum- and glucocorticoid-induced kinase 3 (SGK3), which is ubiquitously expressed in mammals, is regulated by estrogens and androgens. SGK3 is activated by insulin and growth factors through signaling pathways involving phosphatidylinositol-3-kinase (PI3K), 3-phosphoinositide-dependent kinase-1 (PDK-1), and mammalian target of rapamycin complex 2 (mTORC2). Activated SGK3 can activate ion channels (TRPV5/6, SOC, Kv1.3, Kv1.5, Kv7.1, BKCa, Kir2.1, Kir2.2, ENaC, Nav1.5, ClC-2, and ClC Ka), carriers and receptors (Npt2a, Npt2b, NHE3, GluR1, GluR6, SN1, EAAT1, EAAT2, EAAT4, EAAT5, SGLT1, SLC1A5, SLC6A19, SLC6A8, and NaDC1), and Na+/K+-ATPase, promoting the transportation of calcium, phosphorus, sodium, glucose, and neutral amino acids in the kidney and intestine, the absorption of potassium and neutral amino acids in the renal tubules, the transportation of glutamate and glutamine in the nervous system, and the transportation of creatine. SGK3-sensitive transporters contribute to a variety of physiological and pathophysiological processes, such as maintaining calcium and phosphorus homeostasis, hydro-salinity balance and acid-base balance, cell proliferation, muscle action potential, cardiac and neural electrophysiological disturbances, bone density, intestinal nutrition absorption, immune function, and multiple substance metabolism. These processes are related to kidney stones, hypophosphorous rickets, multiple syndromes, arrhythmia, hypertension, heart failure, epilepsy, Alzheimer's disease, amyotrophic lateral sclerosis, glaucoma, ataxia idiopathic deafness, and other diseases.
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Affiliation(s)
- Qian-Qian Liao
- Department of Nephrology, Tongji Medical College, Union Hospital, Huazhong University of Science and Technology, Wuhan, China
| | - Qing-Qing Dong
- Department of Nephrology, Tongji Medical College, Union Hospital, Huazhong University of Science and Technology, Wuhan, China
- Department of Nephrology, The Second Affiliated Hospital, Chongqing Medical University, Chongqing, China
| | - Hui Zhang
- Department of Nephrology, Tongji Medical College, Union Hospital, Huazhong University of Science and Technology, Wuhan, China
| | - Hua-Pan Shu
- Department of Nephrology, Tongji Medical College, Union Hospital, Huazhong University of Science and Technology, Wuhan, China
| | - Yu-Chi Tu
- Department of Nephrology, Tongji Medical College, Union Hospital, Huazhong University of Science and Technology, Wuhan, China
| | - Li-Jun Yao
- Department of Nephrology, Tongji Medical College, Union Hospital, Huazhong University of Science and Technology, Wuhan, China
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9
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Drion C. Homeostatic Control of Neuronal Activity. Physiology (Bethesda) 2022. [DOI: 10.5772/intechopen.108577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
For healthy brain functioning, it is crucial that neuronal networks do not become hyperactive, but also, that they remain excitable. Homeostatic mechanisms ensure that neuronal activity remains within a functional range. How does that work? In this chapter, we will explore homeostatic control of neuronal activity. We will start by introducing the basics of neuronal communication to establish what makes a neuron excitable. Then, we will learn how neurons are able to tune their own excitability, which is called homeostatic intrinsic plasticity. Next, we will discuss the ability of neurons to tune the strength of their connections to other neurons. This is called homeostatic synaptic plasticity and involves synaptic scaling, the up- and downregulation of receptors, and the control of neurotransmitter release. Finally, we will review the role of glia in neuronal network homeostasis and discuss disorders where the homeostatic control of neuronal activity is compromised.
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10
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Abram M, Jakubiec M, Reeb K, Cheng MH, Gedschold R, Rapacz A, Mogilski S, Socała K, Nieoczym D, Szafarz M, Latacz G, Szulczyk B, Kalinowska-Tłuścik J, Gawel K, Esguerra CV, Wyska E, Müller CE, Bahar I, Fontana ACK, Wlaź P, Kamiński RM, Kamiński K. Discovery of ( R)- N-Benzyl-2-(2,5-dioxopyrrolidin-1-yl)propanamide [ (R)-AS-1], a Novel Orally Bioavailable EAAT2 Modulator with Drug-like Properties and Potent Antiseizure Activity In Vivo. J Med Chem 2022; 65:11703-11725. [PMID: 35984707 PMCID: PMC9469208 DOI: 10.1021/acs.jmedchem.2c00534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
(R)-7 [(R)-AS-1] showed broad-spectrum antiseizure activity across in vivo mouse seizure models: maximal electroshock (MES), 6 Hz (32/44 mA), acute pentylenetetrazol (PTZ), and PTZ-kindling. A remarkable separation between antiseizure activity and CNS-related adverse effects was also observed. In vitro studies with primary glia cultures and COS-7 cells expressing the glutamate transporter EAAT2 showed enhancement of glutamate uptake, revealing a stereoselective positive allosteric modulator (PAM) effect, further supported by molecular docking simulations. (R)-7 [(R)-AS-1] was not active in EAAT1 and EAAT3 assays and did not show significant off-target activity, including interactions with targets reported for marketed antiseizure drugs, indicative of a novel and unprecedented mechanism of action. Both in vivo pharmacokinetic and in vitro absorption, distribution, metabolism, excretion, toxicity (ADME-Tox) profiles confirmed the favorable drug-like potential of the compound. Thus, (R)-7 [(R)-AS-1] may be considered as the first-in-class small-molecule PAM of EAAT2 with potential for further preclinical and clinical development in epilepsy and possibly other CNS disorders.
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Affiliation(s)
- Michał Abram
- Department of Medicinal Chemistry, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, 30-688Krakow, Poland
| | - Marcin Jakubiec
- Department of Medicinal Chemistry, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, 30-688Krakow, Poland
| | - Katelyn Reeb
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania19102, United States
| | - Mary Hongying Cheng
- Department of Computational and Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania15213, United States
| | - Robin Gedschold
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical & Medicinal Chemistry, Rheinische Friedrich-Wilhelms-Universität Bonn, An der Immenburg 4, D-53121Bonn, Germany
| | - Anna Rapacz
- Department of Pharmacodynamics, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, 30-688Krakow, Poland
| | - Szczepan Mogilski
- Department of Pharmacodynamics, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, 30-688Krakow, Poland
| | - Katarzyna Socała
- Department of Animal Physiology and Pharmacology, Institute of Biological Sciences, Faculty of Biology and Biotechnology, Maria Curie-Skłodowska University, Akademicka 19, 20-033Lublin, Poland
| | - Dorota Nieoczym
- Department of Animal Physiology and Pharmacology, Institute of Biological Sciences, Faculty of Biology and Biotechnology, Maria Curie-Skłodowska University, Akademicka 19, 20-033Lublin, Poland
| | - Małgorzata Szafarz
- Department of Pharmacokinetics and Physical Pharmacy, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, 30-688Krakow, Poland
| | - Gniewomir Latacz
- Department of Technology and Biotechnology of Drugs, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, 30-688Krakow, Poland
| | - Bartłomiej Szulczyk
- Department of Pharmacodynamics, Centre for Preclinical Research and Technology, Medical University of Warsaw, Banacha 1B, 02-097Warsaw, Poland
| | - Justyna Kalinowska-Tłuścik
- Department of Crystal Chemistry and Crystal Physics, Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387Krakow, Poland
| | - Kinga Gawel
- Department of Experimental and Clinical Pharmacology, Medical University of Lublin, Jaczewskiego 8B, 20-090Lublin, Poland
| | - Camila V Esguerra
- Chemical Neuroscience Group, Centre for Molecular Medicine Norway, University of Oslo, Gaustadalléen 21, Forskningsparken, 0349Oslo, Norway
| | - Elżbieta Wyska
- Department of Pharmacokinetics and Physical Pharmacy, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, 30-688Krakow, Poland
| | - Christa E Müller
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical & Medicinal Chemistry, Rheinische Friedrich-Wilhelms-Universität Bonn, An der Immenburg 4, D-53121Bonn, Germany
| | - Ivet Bahar
- Department of Computational and Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania15213, United States
| | - Andréia C K Fontana
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania19102, United States
| | - Piotr Wlaź
- Department of Animal Physiology and Pharmacology, Institute of Biological Sciences, Faculty of Biology and Biotechnology, Maria Curie-Skłodowska University, Akademicka 19, 20-033Lublin, Poland
| | - Rafał M Kamiński
- Department of Medicinal Chemistry, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, 30-688Krakow, Poland
| | - Krzysztof Kamiński
- Department of Medicinal Chemistry, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, 30-688Krakow, Poland
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11
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Sha L, Li G, Zhang X, Lin Y, Qiu Y, Deng Y, Zhu W, Xu Q. Pharmacological induction of AMFR increases functional EAAT2 oligomer levels and reduces epileptic seizures in mice. JCI Insight 2022; 7:160247. [PMID: 35938532 PMCID: PMC9462477 DOI: 10.1172/jci.insight.160247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Accepted: 06/24/2022] [Indexed: 11/29/2022] Open
Abstract
Dysregulation of excitatory amino acid transporter 2 (EAAT2) contributes to the development of temporal lobe epilepsy (TLE). Several strategies for increasing total EAAT2 levels have been proposed. However, the mechanism underlying the oligomeric assembly of EAAT2, impairment of which inhibits the formation of functional oligomers by EAAT2 monomers, is still poorly understood. In the present study, we identified E3 ubiquitin ligase AMFR as an EAAT2-interacting protein. AMFR specifically increased the level of EAAT2 oligomers rather than inducing protein degradation through K542-specific ubiquitination. By using tissues from humans with TLE and epilepsy model mice, we observed that AMFR and EAAT2 oligomer levels were simultaneously decreased in the hippocampus. Screening of 2386 FDA-approved drugs revealed that the most common analgesic/antipyretic medicine, acetaminophen (APAP), can induce AMFR transcriptional activation via transcription factor SP1. Administration of APAP protected against pentylenetetrazol-induced epileptogenesis. In mice with chronic epilepsy, APAP treatment partially reduced the occurrence of spontaneous seizures and greatly enhanced the antiepileptic effects of 17AAG, an Hsp90 inhibitor that upregulates total EAAT2 levels, when the 2 compounds were administered together. In summary, our studies reveal an essential role for AMFR in regulating the oligomeric state of EAAT2 and suggest that APAP can improve the efficacy of EAAT2-targeted antiepileptic treatments.
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Affiliation(s)
- Longze Sha
- State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Beijing, China
- Neuroscience Center, Chinese Academy of Medical Sciences, Beijing, China
| | - Guanjun Li
- State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Beijing, China
| | - Xiuneng Zhang
- State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Beijing, China
| | - Yarong Lin
- State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Beijing, China
| | - Yunjie Qiu
- State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Beijing, China
| | - Yu Deng
- State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Beijing, China
| | - Wanwan Zhu
- State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Beijing, China
- Neuroscience Center, Chinese Academy of Medical Sciences, Beijing, China
| | - Qi Xu
- State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Beijing, China
- Neuroscience Center, Chinese Academy of Medical Sciences, Beijing, China
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12
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Hills KE, Kostarelos K, Wykes RC. Converging Mechanisms of Epileptogenesis and Their Insight in Glioblastoma. Front Mol Neurosci 2022; 15:903115. [PMID: 35832394 PMCID: PMC9271928 DOI: 10.3389/fnmol.2022.903115] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 05/25/2022] [Indexed: 12/15/2022] Open
Abstract
Glioblastoma (GBM) is the most common and advanced form of primary malignant tumor occurring in the adult central nervous system, and it is frequently associated with epilepsy, a debilitating comorbidity. Seizures are observed both pre- and post-surgical resection, indicating that several pathophysiological mechanisms are shared but also prompting questions about how the process of epileptogenesis evolves throughout GBM progression. Molecular mutations commonly seen in primary GBM, i.e., in PTEN and p53, and their associated downstream effects are known to influence seizure likelihood. Similarly, various intratumoral mechanisms, such as GBM-induced blood-brain barrier breakdown and glioma-immune cell interactions within the tumor microenvironment are also cited as contributing to network hyperexcitability. Substantial alterations to peri-tumoral glutamate and chloride transporter expressions, as well as widespread dysregulation of GABAergic signaling are known to confer increased epileptogenicity and excitotoxicity. The abnormal characteristics of GBM alter neuronal network function to result in metabolically vulnerable and hyperexcitable peri-tumoral tissue, properties the tumor then exploits to favor its own growth even post-resection. It is evident that there is a complex, dynamic interplay between GBM and epilepsy that promotes the progression of both pathologies. This interaction is only more complicated by the concomitant presence of spreading depolarization (SD). The spontaneous, high-frequency nature of GBM-associated epileptiform activity and SD-associated direct current (DC) shifts require technologies capable of recording brain signals over a wide bandwidth, presenting major challenges for comprehensive electrophysiological investigations. This review will initially provide a detailed examination of the underlying mechanisms that promote network hyperexcitability in GBM. We will then discuss how an investigation of these pathologies from a network level, and utilization of novel electrophysiological tools, will yield a more-effective, clinically-relevant understanding of GBM-related epileptogenesis. Further to this, we will evaluate the clinical relevance of current preclinical research and consider how future therapeutic advancements may impact the bidirectional relationship between GBM, SDs, and seizures.
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Affiliation(s)
- Kate E. Hills
- Nanomedicine Lab, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Kostas Kostarelos
- Nanomedicine Lab, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
- Catalan Institute for Nanoscience and Nanotechnology (ICN2), Edifici ICN2, Campus UAB, Barcelona, Spain
| | - Robert C. Wykes
- Nanomedicine Lab, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
- Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, London, United Kingdom
- *Correspondence: Robert C. Wykes
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13
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Garcia JP, Dulla CG. Oops!...Glutamate Did it Again. Epilepsy Curr 2022; 22:61-63. [PMID: 35233203 PMCID: PMC8832338 DOI: 10.1177/15357597211055287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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14
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Green JL, Dos Santos WF, Fontana ACK. Role of glutamate excitotoxicity and glutamate transporter EAAT2 in epilepsy: Opportunities for novel therapeutics development. Biochem Pharmacol 2021; 193:114786. [PMID: 34571003 DOI: 10.1016/j.bcp.2021.114786] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 09/21/2021] [Accepted: 09/22/2021] [Indexed: 12/21/2022]
Abstract
Epilepsy is a complex neurological syndrome characterized by seizures resulting from neuronal hyperexcitability and sudden and synchronized bursts of electrical discharges. Impaired astrocyte function that results in glutamate excitotoxicity has been recognized to play a key role in the pathogenesis of epilepsy. While there are 26 drugs marketed as anti-epileptic drugs no current treatments are disease modifying as they only suppress seizures rather than the development and progression of epilepsy. Excitatory amino acid transporters (EAATs) are critical for maintaining low extracellular glutamate concentrations and preventing excitotoxicity. When extracellular glutamate concentrations rise to abnormal levels, glutamate receptor overactivation and the subsequent excessive influx of calcium into the post-synaptic neuron can trigger cell death pathways. In this review we discuss targeting EAAT2, the predominant glutamate transporter in the CNS, as a promising approach for developing therapies for epilepsy. EAAT2 upregulation via transcriptional and translational regulation has proven successful in vivo in reducing spontaneous recurrent seizures and offering neuroprotective effects. Another approach to regulate EAAT2 activity is through positive allosteric modulation (PAM). Novel PAMs of EAAT2 have recently been identified and are under development, representing a promising approach for the advance of novel therapeutics for epilepsy.
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Affiliation(s)
- Jennifer Leigh Green
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA, 19102, United States
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15
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Sears SM, Hewett SJ. Influence of glutamate and GABA transport on brain excitatory/inhibitory balance. Exp Biol Med (Maywood) 2021; 246:1069-1083. [PMID: 33554649 DOI: 10.1177/1535370221989263] [Citation(s) in RCA: 76] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
An optimally functional brain requires both excitatory and inhibitory inputs that are regulated and balanced. A perturbation in the excitatory/inhibitory balance-as is the case in some neurological disorders/diseases (e.g. traumatic brain injury Alzheimer's disease, stroke, epilepsy and substance abuse) and disorders of development (e.g. schizophrenia, Rhett syndrome and autism spectrum disorder)-leads to dysfunctional signaling, which can result in impaired cognitive and motor function, if not frank neuronal injury. At the cellular level, transmission of glutamate and GABA, the principle excitatory and inhibitory neurotransmitters in the central nervous system control excitatory/inhibitory balance. Herein, we review the synthesis, release, and signaling of GABA and glutamate followed by a focused discussion on the importance of their transport systems to the maintenance of excitatory/inhibitory balance.
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Affiliation(s)
- Sheila Ms Sears
- Department of Biology, Program in Neuroscience, 2029Syracuse University, Syracuse, NY 13244, USA
| | - Sandra J Hewett
- Department of Biology, Program in Neuroscience, 2029Syracuse University, Syracuse, NY 13244, USA
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16
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Juvale IIA, Che Has AT. Possible interplay between the theories of pharmacoresistant epilepsy. Eur J Neurosci 2020; 53:1998-2026. [PMID: 33306252 DOI: 10.1111/ejn.15079] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Revised: 11/22/2020] [Accepted: 12/04/2020] [Indexed: 02/06/2023]
Abstract
Epilepsy is one of the oldest known neurological disorders and is characterized by recurrent seizure activity. It has a high incidence rate, affecting a broad demographic in both developed and developing countries. Comorbid conditions are frequent in patients with epilepsy and have detrimental effects on their quality of life. Current management options for epilepsy include the use of anti-epileptic drugs, surgery, or a ketogenic diet. However, more than 30% of patients diagnosed with epilepsy exhibit drug resistance to anti-epileptic drugs. Further, surgery and ketogenic diets do little to alleviate the symptoms of patients with pharmacoresistant epilepsy. Thus, there is an urgent need to understand the underlying mechanisms of pharmacoresistant epilepsy to design newer and more effective anti-epileptic drugs. Several theories of pharmacoresistant epilepsy have been suggested over the years, the most common being the gene variant hypothesis, network hypothesis, multidrug transporter hypothesis, and target hypothesis. In our review, we discuss the main theories of pharmacoresistant epilepsy and highlight a possible interconnection between their mechanisms that could lead to the development of novel therapies for pharmacoresistant epilepsy.
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Affiliation(s)
- Iman Imtiyaz Ahmed Juvale
- Department of Neurosciences, School of Medical Sciences, Universiti Sains Malaysia, Kubang Kerian, Malaysia
| | - Ahmad Tarmizi Che Has
- Department of Neurosciences, School of Medical Sciences, Universiti Sains Malaysia, Kubang Kerian, Malaysia
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17
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Todd AC, Hardingham GE. The Regulation of Astrocytic Glutamate Transporters in Health and Neurodegenerative Diseases. Int J Mol Sci 2020; 21:E9607. [PMID: 33348528 PMCID: PMC7766851 DOI: 10.3390/ijms21249607] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2020] [Revised: 12/04/2020] [Accepted: 12/11/2020] [Indexed: 12/24/2022] Open
Abstract
The astrocytic glutamate transporters excitatory amino acid transporters 1 and 2 (EAAT1 and EAAT2) play a key role in nervous system function to maintain extracellular glutamate levels at low levels. In physiology, this is essential for the rapid uptake of synaptically released glutamate, maintaining the temporal fidelity of synaptic transmission. However, EAAT1/2 hypo-expression or hypo-function are implicated in several disorders, including epilepsy and neurodegenerative diseases, as well as being observed naturally with aging. This not only disrupts synaptic information transmission, but in extremis leads to extracellular glutamate accumulation and excitotoxicity. A key facet of EAAT1/2 expression in astrocytes is a requirement for signals from other brain cell types in order to maintain their expression. Recent evidence has shown a prominent role for contact-dependent neuron-to-astrocyte and/or endothelial cell-to-astrocyte Notch signalling for inducing and maintaining the expression of these astrocytic glutamate transporters. The relevance of this non-cell-autonomous dependence to age- and neurodegenerative disease-associated decline in astrocytic EAAT expression is discussed, plus the implications for disease progression and putative therapeutic strategies.
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Affiliation(s)
- Alison C. Todd
- UK Dementia Research Institute at the University of Edinburgh, Chancellor’s Building, Edinburgh Medical School, Edinburgh EH16 4SB, UK;
- Centre for Discovery Brain Sciences, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh EH8 9XD, UK
| | - Giles E. Hardingham
- UK Dementia Research Institute at the University of Edinburgh, Chancellor’s Building, Edinburgh Medical School, Edinburgh EH16 4SB, UK;
- Centre for Discovery Brain Sciences, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh EH8 9XD, UK
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18
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Verhoog QP, Holtman L, Aronica E, van Vliet EA. Astrocytes as Guardians of Neuronal Excitability: Mechanisms Underlying Epileptogenesis. Front Neurol 2020; 11:591690. [PMID: 33324329 PMCID: PMC7726323 DOI: 10.3389/fneur.2020.591690] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 10/26/2020] [Indexed: 12/11/2022] Open
Abstract
Astrocytes are key homeostatic regulators in the central nervous system and play important roles in physiology. After brain damage caused by e.g., status epilepticus, traumatic brain injury, or stroke, astrocytes may adopt a reactive phenotype. This process of reactive astrogliosis is important to restore brain homeostasis. However, persistent reactive astrogliosis can be detrimental for the brain and contributes to the development of epilepsy. In this review, we will focus on physiological functions of astrocytes in the normal brain as well as pathophysiological functions in the epileptogenic brain, with a focus on acquired epilepsy. We will discuss the role of astrocyte-related processes in epileptogenesis, including reactive astrogliosis, disturbances in energy supply and metabolism, gliotransmission, and extracellular ion concentrations, as well as blood-brain barrier dysfunction and dysregulation of blood flow. Since dysfunction of astrocytes can contribute to epilepsy, we will also discuss their role as potential targets for new therapeutic strategies.
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Affiliation(s)
- Quirijn P. Verhoog
- Leiden Academic Center for Drug Research, Leiden University, Leiden, Netherlands
- Department of Neuropathology, Amsterdam Neuroscience, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Linda Holtman
- Leiden Academic Center for Drug Research, Leiden University, Leiden, Netherlands
| | - Eleonora Aronica
- Department of Neuropathology, Amsterdam Neuroscience, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
- Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede, Netherlands
| | - Erwin A. van Vliet
- Department of Neuropathology, Amsterdam Neuroscience, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
- Center for Neuroscience, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, Netherlands
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19
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Evolving targets for anti-epileptic drug discovery. Eur J Pharmacol 2020; 887:173582. [DOI: 10.1016/j.ejphar.2020.173582] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 09/14/2020] [Accepted: 09/15/2020] [Indexed: 12/27/2022]
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20
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Zhang Y, Liu Y, Jia Y, Zhao Y, Ma C, Bao X, Meng X, Dou W, Wang X, Ge W. Proteomic profiling of sclerotic hippocampus revealed dysregulated packaging of vesicular neurotransmitters in temporal lobe epilepsy. Epilepsy Res 2020; 166:106412. [DOI: 10.1016/j.eplepsyres.2020.106412] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 06/17/2020] [Accepted: 06/30/2020] [Indexed: 12/31/2022]
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21
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Peterson AR, Binder DK. Astrocyte Glutamate Uptake and Signaling as Novel Targets for Antiepileptogenic Therapy. Front Neurol 2020; 11:1006. [PMID: 33013665 PMCID: PMC7505989 DOI: 10.3389/fneur.2020.01006] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 07/30/2020] [Indexed: 12/14/2022] Open
Abstract
Astrocytes regulate and respond to extracellular glutamate levels in the central nervous system (CNS) via the Na+-dependent glutamate transporters glutamate transporter-1 (GLT-1) and glutamate aspartate transporter (GLAST) and the metabotropic glutamate receptors (mGluR) 3 and mGluR5. Both impaired astrocytic glutamate clearance and changes in metabotropic glutamate signaling could contribute to the development of epilepsy. Dysregulation of astrocytic glutamate transporters, GLT-1 and GLAST, is a common finding across patients and preclinical seizure models. Astrocytic metabotropic glutamate receptors, particularly mGluR5, have been shown to be dysregulated in both humans and animal models of temporal lobe epilepsy (TLE). In this review, we synthesize the available evidence regarding astrocytic glutamate homeostasis and astrocytic mGluRs in the development of epilepsy. Modulation of astrocyte glutamate uptake and/or mGluR activation could lead to novel glial therapeutics for epilepsy.
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Affiliation(s)
- Allison R Peterson
- Division of Biomedical Sciences, Center for Glial-Neuronal Interactions, School of Medicine, University of California, Riverside, Riverside, CA, United States
| | - Devin K Binder
- Division of Biomedical Sciences, Center for Glial-Neuronal Interactions, School of Medicine, University of California, Riverside, Riverside, CA, United States
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22
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Martinez D, Rogers RC, Hasser EM, Hermann GE, Kline DD. Loss of excitatory amino acid transporter restraint following chronic intermittent hypoxia contributes to synaptic alterations in nucleus tractus solitarii. J Neurophysiol 2020; 123:2122-2135. [PMID: 32347148 PMCID: PMC7311725 DOI: 10.1152/jn.00766.2019] [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] [Indexed: 01/16/2023] Open
Abstract
Peripheral viscerosensory afferent signals are transmitted to the nucleus tractus solitarii (nTS) via release of glutamate. Following release, glutamate is removed from the extrasynaptic and synaptic cleft via excitatory amino acid transporters (EAATs), thus limiting glutamate receptor activation or over activation, and maintaining its working range. We have shown that EAAT block with the antagonist threo-β-benzyloxyaspartic acid (TBOA) depolarized nTS neurons and increased spontaneous excitatory postsynaptic current (sEPSC) frequency yet reduced the amplitude of afferent (TS)-evoked EPSCs (TS-EPSCs). Interestingly, chronic intermittent hypoxia (CIH), a model of obstructive sleep apnea (OSA), produces similar synaptic responses as EAAT block. We hypothesized EAAT expression or function are downregulated after CIH, and this reduction in glutamate removal contributes to the observed neurophysiological responses. To test this hypothesis, we used brain slice electrophysiology and imaging of glutamate release and TS-afferent Ca2+ to compare nTS properties of rats exposed to 10 days of normoxia (Norm; 21%O2) or CIH. Results show that EAAT blockade with (3S)-3-[[3-[[4-(trifluoromethyl)benzoyl]-amino]phenyl]methoxy]-l-aspartic acid (TFB-TBOA) in Norm caused neuronal depolarization, generation of an inward current, and increased spontaneous synaptic activity. The latter augmentation was eliminated by inclusion of tetrodotoxin in the perfusate. TS stimulation during TFB-TBOA also elevated extracellular glutamate and decreased presynaptic Ca2+ and TS-EPSC amplitude. In CIH, the effects of EAAT block are eliminated or attenuated. CIH reduced EAAT expression in nTS, which may contribute to the attenuated function seen in this condition. Therefore, CIH reduces EAAT influence on synaptic and neuronal activity, which may lead to the physiological consequences seen in OSA and CIH.NEW & NOTEWORTHY Removal of excitatory amino acid transporter (EAAT) restraint increases spontaneous synaptic activity yet decreases afferent [tractus solitarius (TS)]-driven excitatory postsynaptic current (EPSC) amplitude. In the chronic intermittent hypoxia model of obstructive sleep apnea, this restraint is lost due to reduction in EAAT expression and function. Thus EAATs are important in controlling elevated glutamatergic signaling, and loss of such control results in maladaptive synaptic signaling.
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Affiliation(s)
- Diana Martinez
- 1Department of Biomedical Sciences and Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
| | | | - Eileen M. Hasser
- 1Department of Biomedical Sciences and Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri,2Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri
| | | | - David D. Kline
- 1Department of Biomedical Sciences and Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
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23
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Armada-Moreira A, Gomes JI, Pina CC, Savchak OK, Gonçalves-Ribeiro J, Rei N, Pinto S, Morais TP, Martins RS, Ribeiro FF, Sebastião AM, Crunelli V, Vaz SH. Going the Extra (Synaptic) Mile: Excitotoxicity as the Road Toward Neurodegenerative Diseases. Front Cell Neurosci 2020; 14:90. [PMID: 32390802 PMCID: PMC7194075 DOI: 10.3389/fncel.2020.00090] [Citation(s) in RCA: 145] [Impact Index Per Article: 36.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 03/26/2020] [Indexed: 12/13/2022] Open
Abstract
Excitotoxicity is a phenomenon that describes the toxic actions of excitatory neurotransmitters, primarily glutamate, where the exacerbated or prolonged activation of glutamate receptors starts a cascade of neurotoxicity that ultimately leads to the loss of neuronal function and cell death. In this process, the shift between normal physiological function and excitotoxicity is largely controlled by astrocytes since they can control the levels of glutamate on the synaptic cleft. This control is achieved through glutamate clearance from the synaptic cleft and its underlying recycling through the glutamate-glutamine cycle. The molecular mechanism that triggers excitotoxicity involves alterations in glutamate and calcium metabolism, dysfunction of glutamate transporters, and malfunction of glutamate receptors, particularly N-methyl-D-aspartic acid receptors (NMDAR). On the other hand, excitotoxicity can be regarded as a consequence of other cellular phenomena, such as mitochondrial dysfunction, physical neuronal damage, and oxidative stress. Regardless, it is known that the excessive activation of NMDAR results in the sustained influx of calcium into neurons and leads to several deleterious consequences, including mitochondrial dysfunction, reactive oxygen species (ROS) overproduction, impairment of calcium buffering, the release of pro-apoptotic factors, among others, that inevitably contribute to neuronal loss. A large body of evidence implicates NMDAR-mediated excitotoxicity as a central mechanism in the pathogenesis of many neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), Alzheimer's disease (AD), and epilepsy. In this review article, we explore different causes and consequences of excitotoxicity, discuss the involvement of NMDAR-mediated excitotoxicity and its downstream effects on several neurodegenerative disorders, and identify possible strategies to study new aspects of these diseases that may lead to the discovery of new therapeutic approaches. With the understanding that excitotoxicity is a common denominator in neurodegenerative diseases and other disorders, a new perspective on therapy can be considered, where the targets are not specific symptoms, but the underlying cellular phenomena of the disease.
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Affiliation(s)
- Adam Armada-Moreira
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus, Denmark
| | - Joana I. Gomes
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal
| | - Carolina Campos Pina
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal
| | - Oksana K. Savchak
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal
| | - Joana Gonçalves-Ribeiro
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal
| | - Nádia Rei
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal
| | - Sara Pinto
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal
| | - Tatiana P. Morais
- Neuroscience Division, School of Bioscience, Cardiff University, Cardiff, United Kingdom
| | - Robertta Silva Martins
- Laboratório de Neurofarmacologia, Instituto Biomédico, Universidade Federal Fluminense, Niterói, Brazil
| | - Filipa F. Ribeiro
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal
| | - Ana M. Sebastião
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal
| | - Vincenzo Crunelli
- Neuroscience Division, School of Bioscience, Cardiff University, Cardiff, United Kingdom
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Msida, Malta
| | - Sandra H. Vaz
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal
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24
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Riquelme J, Wellmann M, Sotomayor-Zárate R, Bonansco C. Gliotransmission: A Novel Target for the Development of Antiseizure Drugs. Neuroscientist 2020; 26:293-309. [PMID: 31976817 DOI: 10.1177/1073858420901474] [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] [Indexed: 12/16/2022]
Abstract
For more than a century, epilepsy has remained an incapacitating neurological disorder with a high incidence worldwide. Mesial temporal lobe epilepsy (TLE) is a common type of epilepsy without an effective pharmacological treatment. An increase in excitability and hypersynchrony of electrical neuronal activity during development are typically associated with an excitatory/inhibitory imbalance in the neuronal network. Astrocytes release gliotransmitters, which can regulate neuronal excitability and synaptic transmission; therefore, the classical neurocentric vision of the cellular basis of epileptogenesis has begun to change. Growing evidence suggests that the key contribution of astrocyte-to-neuron signaling in the mechanisms underlies the initiation, propagation, and recurrence of seizure activity. The aim of this review was to summarize current evidence obtained from experimental models that suggest how alterations in astroglial modulation of synaptic transmission and neuronal activity contribute to the development of this brain disease. In this article, we will summarize the main pharmacological, Ca2+-imaging, and electrophysiological findings in the gliotransmitter-mediated modulation of neuronal activity and their possible regulation as a novel cellular target for the development of pharmacological strategies for treating refractory epilepsies.
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Affiliation(s)
- Julio Riquelme
- Escuela de Medicina, Facultad de Medicina, Universidad de Valparaíso, Valparaíso, Chile.,Servicio de Neurología, Hospital Carlos Van Buren, Valparaíso, Chile
| | - Mario Wellmann
- Escuela de Fonoaudiología, Facultad de Medicina, Universidad de Valparaíso, Valparaíso, Chile.,Centro de Neurobiología y Fisiología Integrativa (CENFI), Instituto de Fisiología, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Ramón Sotomayor-Zárate
- Centro de Neurobiología y Fisiología Integrativa (CENFI), Instituto de Fisiología, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Christian Bonansco
- Centro de Neurobiología y Fisiología Integrativa (CENFI), Instituto de Fisiología, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
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Vargas-Sánchez K, Mogilevskaya M, Rodríguez-Pérez J, Rubiano MG, Javela JJ, González-Reyes RE. Astroglial role in the pathophysiology of status epilepticus: an overview. Oncotarget 2018; 9:26954-26976. [PMID: 29928494 PMCID: PMC6003549 DOI: 10.18632/oncotarget.25485] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2017] [Accepted: 05/09/2018] [Indexed: 12/11/2022] Open
Abstract
Status epilepticus is a medical emergency with elevated morbidity and mortality rates, and represents a leading cause of epilepsy-related deaths. Though status epilepticus can occur at any age, it manifests more likely in children and elderly people. Despite the common prevalence of epileptic disorders, a complete explanation for the mechanisms leading to development of self-limited or long lasting seizures (as in status epilepticus) are still lacking. Apart from neurons, research evidence suggests the involvement of immune and glial cells in epileptogenesis. Among glial cells, astrocytes represent an ideal target for the study of the pathophysiology of status epilepticus, due to their key role in homeostatic balance of the central nervous system. During status epilepticus, astroglial cells are activated by the presence of cytokines, damage associated molecular patterns and reactive oxygen species. The persistent activation of astrocytes leads to a decrease in glutamate clearance with a corresponding accumulation in the synaptic extracellular space, increasing the chance of neuronal excitotoxicity. Moreover, major alterations in astrocytic gap junction coupling, inflammation and receptor expression, facilitate the generation of seizures. Astrocytes are also involved in dysregulation of inhibitory transmission in the central nervous system and directly participate in ionic homeostatic alterations during status epilepticus. In the present review, we focus on the functional and structural changes in astrocytic activity that participate in the development and maintenance of status epilepticus, with special attention on concurrent inflammatory alterations. We also include potential astrocytic treatment targets for status epilepticus.
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Affiliation(s)
- Karina Vargas-Sánchez
- Biomedical Sciences Research Group, School of Medicine, Universidad Antonio Nariño, Bogotá, Colombia
| | | | - John Rodríguez-Pérez
- Biomedical Sciences Research Group, School of Medicine, Universidad Antonio Nariño, Bogotá, Colombia
| | - María G Rubiano
- Biomedical Sciences Research Group, School of Medicine, Universidad Antonio Nariño, Bogotá, Colombia
| | - José J Javela
- Grupo de Clínica y Salud Mental, Programa de Psicología, Universidad Católica de Pereira, Pereira, Colombia
| | - Rodrigo E González-Reyes
- Universidad del Rosario, Escuela de Medicina y Ciencias de la Salud, GI en Neurociencias-NeURos, Bogotá, Colombia
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26
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Mohammadi M, Zare Z, Allah-Moradi E, Vaezi N, Valadan R, Tehrani M. Alterations in mRNA and protein expression of glutamate transporters in rat hippocampus after paraoxon exposure. Neurotoxicology 2016; 57:251-257. [PMID: 27769869 DOI: 10.1016/j.neuro.2016.10.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 10/15/2016] [Accepted: 10/15/2016] [Indexed: 01/30/2023]
Abstract
Organophosphates affect brain function through a variety of mechanisms beyond their shared role as cholinesterase inhibitors. The aim of the current study was to investigate the changes in the expression of glial (GLAST and GLT-1) and neuronal (EAAC1) glutamate transporters at mRNA and protein levels in paraoxon-treated rat hippocampus. Adult male Wistar rats were intraperitoneally treated with either vehicle (corn oil) or one of three dosages of paraoxon (0.3, 0.7 or 1mg/kg). After 4 or 18h, both hippocampi of each rat were collected to detect mRNA and protein expression of glutamate transporters using the quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) and western blotting, respectively. Animals treated with 0.3mg/kg paraoxon showed no difference in mRNA and protein levels of the glutamate transporters when compared with control group. At 4h after exposure with 0.7 and 1mg/kg paraoxon, the expression of GLAST and GLT-1 increased at mRNA and protein levels and remained elevated after 18h. No difference in the expression of EAAC1 at mRNA and protein levels was observed in any paraoxon-treated groups compared with the control group. This study showed an increased expression of glial (GLAST and GLT-1), but not neuronal (EAAC1) glutamate transporters, in adult rat hippocampus following administration of convulsive dosages of paraoxon. These suggest a protective and compensatory adaptation for effective uptake of glutamate in hippocampus induced by paraoxon and thus attenuating seizure activity.
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Affiliation(s)
- Moslem Mohammadi
- Department of Physiology & Pharmacology, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran
| | - Zohreh Zare
- Department of Anatomical Sciences, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran
| | - Esmaeil Allah-Moradi
- Department of Immunology, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran
| | - Narges Vaezi
- Department of Toxicology and Pharmacology, School of Pharmacy, Mazandaran University of Medical Sciences, Sari, Iran
| | - Reza Valadan
- Department of Immunology, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran; Molecular and Cell Biology Research Center, Mazandaran University of Medical Sciences, Sari, Iran
| | - Mohsen Tehrani
- Department of Immunology, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran; Molecular and Cell Biology Research Center, Mazandaran University of Medical Sciences, Sari, Iran.
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27
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Crucial role of astrocytes in temporal lobe epilepsy. Neuroscience 2016; 323:157-69. [DOI: 10.1016/j.neuroscience.2014.12.047] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Revised: 12/25/2014] [Accepted: 12/30/2014] [Indexed: 11/30/2022]
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Thrombin decreases expression of the glutamate transporter GLAST and inhibits glutamate uptake in primary cortical astrocytes via the Rho kinase pathway. Exp Neurol 2015; 273:288-300. [PMID: 26391563 DOI: 10.1016/j.expneurol.2015.09.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 09/17/2015] [Indexed: 01/08/2023]
Abstract
Astrocyte glutamate transporters GLAST and GLT1 play a key role in regulating neuronal excitation and their levels are altered in patients with epilepsy, and after traumatic brain injury. The mechanisms which regulate their expression are not well understood. We tested the hypothesis that exposure of astrocytes to high levels of thrombin, as may occur after a compromise of the blood-brain barrier, would reduce astrocyte glutamate transporter levels. In isolated rat cortical astrocytes we examined the effects of thrombin on the expression and function of glutamate transporters, and the signaling pathways involved in these responses by using Western blotting and selective inhibitors. Thrombin induced a selective decrease in the expression of GLAST but not GLT1, with a corresponding decrease in the capacity of astrocytes to take up glutamate. Activation of the thrombin receptor PAR-1 with an activating peptide induced a similar decrease in the expression of GLAST and compromise of glutamate uptake. The downregulation of GLAST induced by thrombin was mediated by the mitogen activated protein kinases p38 MAPK, ERK and JNK, but inhibition of these kinases did not prevent the decrease in glutamate uptake induced by thrombin. In contrast, inhibition of the Rho kinase pathway using the specific inhibitor, Y27632, suppressed both the decrease in the expression of GLAST and the decrease in glutamate uptake induced by thrombin. In hippocampal astrocyte cultures, thrombin caused a decrease in both GLAST and GLT1. In tissue resected from brains of children with intractable epilepsy, we found a decrease in the integrity of the blood-brain barrier along with a reduction in immunoreactivity for both transporters which was associated with an increase in cleaved thrombin and reactive astrogliosis. The in vitro results suggest a specific mechanism by which thrombin may lead to a compromise of astrocyte function and enhanced synaptic excitability after the blood-brain barrier is compromised. The human in vivo results provide indirect support evidence linking the compromise of the blood-brain barrier to thrombin-induced reduction in glutamate transporter expression and an increase in neuronal excitation.
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Takahashi K, Foster JB, Lin CLG. Glutamate transporter EAAT2: regulation, function, and potential as a therapeutic target for neurological and psychiatric disease. Cell Mol Life Sci 2015; 72:3489-506. [PMID: 26033496 PMCID: PMC11113985 DOI: 10.1007/s00018-015-1937-8] [Citation(s) in RCA: 121] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Revised: 05/22/2015] [Accepted: 05/26/2015] [Indexed: 12/12/2022]
Abstract
Glutamate is the predominant excitatory neurotransmitter in the central nervous system. Excitatory amino acid transporter 2 (EAAT2) is primarily responsible for clearance of extracellular glutamate to prevent neuronal excitotoxicity and hyperexcitability. EAAT2 plays a critical role in regulation of synaptic activity and plasticity. In addition, EAAT2 has been implicated in the pathogenesis of many central nervous system disorders. In this review, we summarize current understanding of EAAT2, including structure, pharmacology, physiology, and functions, as well as disease relevancy, such as in stroke, Parkinson's disease, epilepsy, amyotrophic lateral sclerosis, Alzheimer's disease, major depressive disorder, and addiction. A large number of studies have demonstrated that up-regulation of EAAT2 protein provides significant beneficial effects in many disease models suggesting EAAT2 activation is a promising therapeutic approach. Several EAAT2 activators have been identified. Further understanding of EAAT2 regulatory mechanisms could improve development of drug-like compounds that spatiotemporally regulate EAAT2.
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Affiliation(s)
- Kou Takahashi
- Department of Neuroscience, The Ohio State University, 333 West 10th Avenue, Columbus, OH 43210 USA
| | - Joshua B. Foster
- Department of Neuroscience, The Ohio State University, 333 West 10th Avenue, Columbus, OH 43210 USA
| | - Chien-Liang Glenn Lin
- Department of Neuroscience, The Ohio State University, 333 West 10th Avenue, Columbus, OH 43210 USA
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30
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Abstract
Astrocytes express ion channels, transmitter receptors, and transporters and, thus, are endowed with the machinery to sense and respond to neuronal activity. Recent studies have implicated that astrocytes play important roles in physiology, but these cells also emerge as crucial actors in epilepsy. Astrocytes are abundantly coupled through gap junctions allowing them to redistribute elevated K(+) and transmitter concentrations from sites of enhanced neuronal activity. Investigation of specimens from patients with pharmacoresistant temporal lobe epilepsy and epilepsy models revealed alterations in expression, localization, and function of astroglial K(+) and water channels. In addition, malfunction of glutamate transporters and the astrocytic glutamate-converting enzyme, glutamine synthetase, has been observed in epileptic tissue. These findings suggest that dysfunctional astrocytes are crucial players in epilepsy and should be considered as promising targets for new therapeutic strategies.
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Affiliation(s)
- Douglas A Coulter
- Departments of Pediatrics and Neuroscience, Perelman School of Medicine, University of Pennsylvania and the Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104-4318
| | - Christian Steinhäuser
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, 53105 Bonn, Germany
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DiNuzzo M, Mangia S, Maraviglia B, Giove F. Physiological bases of the K+ and the glutamate/GABA hypotheses of epilepsy. Epilepsy Res 2014; 108:995-1012. [PMID: 24818957 DOI: 10.1016/j.eplepsyres.2014.04.001] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Revised: 03/20/2014] [Accepted: 04/01/2014] [Indexed: 01/19/2023]
Abstract
Epilepsy is a heterogeneous family of neurological disorders that manifest as seizures, i.e. the hypersynchronous activity of large population of neurons. About 30% of epileptic patients do not respond to currently available antiepileptic drugs. Decades of intense research have elucidated the involvement of a number of possible signaling pathways, however, at present we do not have a fundamental understanding of epileptogenesis. In this paper, we review the literature on epilepsy under a wide-angle perspective, a mandatory choice that responds to the recurrent and unanswered question about what is epiphenomenal and what is causal to the disease. While focusing on the involvement of K+ and glutamate/GABA in determining neuronal hyperexcitability, emphasis is given to astrocytic contribution to epileptogenesis, and especially to loss-of-function of astrocytic glutamine synthetase following reactive astrogliosis, a hallmark of epileptic syndromes. We finally introduce the potential involvement of abnormal glycogen synthesis induced by excess glutamate in increasing susceptibility to seizures.
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Affiliation(s)
- Mauro DiNuzzo
- MARBILab, Museo storico della fisica e Centro di studi e ricerche "Enrico Fermi", Rome, Italy.
| | - Silvia Mangia
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, MN, USA
| | - Bruno Maraviglia
- Dipartimento di Fisica, Sapienza Università di Roma, Rome, Italy; Fondazione Santa Lucia IRCCS, Rome, Italy
| | - Federico Giove
- MARBILab, Museo storico della fisica e Centro di studi e ricerche "Enrico Fermi", Rome, Italy; Dipartimento di Fisica, Sapienza Università di Roma, Rome, Italy
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32
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Wilcox KS, Vezzani A. Does brain inflammation mediate pathological outcomes in epilepsy? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 813:169-83. [PMID: 25012376 PMCID: PMC4867105 DOI: 10.1007/978-94-017-8914-1_14] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Inflammation in the central nervous system (CNS) is associated with epilepsy and is characterized by the increased levels of a complex set of soluble molecules and their receptors in epileptogenic foci with profound neuromodulatory effects. These molecules activate receptor-mediated pathways in glia and neurons that contribute to hyperexcitability in neural networks that underlie seizure generation. As a consequence, exciting new opportunities now exist for novel therapies targeting the various components of the immune system and the associated inflammatory mediators, especially the IL-1β system. This review summarizes recent findings that increased our understanding of the role of inflammation in reducing seizure threshold, contributing to seizure generation, and participating in epileptogenesis. We will discuss preclinical studies supporting the hypothesis that pharmacological inhibition of specific proinflammatory signalings may be useful to treat drug-resistant seizures in human epilepsy, and possibly delay or arrest epileptogenesis.
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Affiliation(s)
- Karen S Wilcox
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT, 84108, USA,
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33
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Gibbons M, Smeal R, Takahashi D, Vargas J, Wilcox K. Contributions of astrocytes to epileptogenesis following status epilepticus: opportunities for preventive therapy? Neurochem Int 2013; 63:660-9. [PMID: 23266599 PMCID: PMC4353644 DOI: 10.1016/j.neuint.2012.12.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Revised: 12/09/2012] [Accepted: 12/13/2012] [Indexed: 12/22/2022]
Abstract
Status epilepticus (SE) is a life threatening condition that often precedes the development of epilepsy. Traditional treatments for epilepsy have been focused on targeting neuronal mechanisms contributing to hyperexcitability, however, approximately 30% of patients with epilepsy do not respond to existing neurocentric pharmacotherapies. A growing body of evidence has demonstrated that profound changes in the morphology and function of astrocytes accompany SE and persist in epilepsy. Astrocytes are increasingly recognized for their diverse roles in modulating neuronal activity, and understanding the changes in astrocytes following SE could provide important clues about the mechanisms underlying seizure generation and termination. By understanding the contributions of astrocytes to the network changes underlying epileptogenesis and the development of epilepsy, we will gain a greater appreciation of the contributions of astrocytes to dynamic circuit changes, which will enable us to develop more successful therapies to prevent and treat epilepsy. This review summarizes changes in astrocytes following SE in animal models and human temporal lobe epilepsy and addresses the functional consequences of those changes that may provide clues to the process of epileptogenesis.
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Affiliation(s)
- M.B. Gibbons
- Interdepartmental Program in Neuroscience, University of Utah, Salt Lake City, UT
| | - R.M. Smeal
- Department of Pharmacology & Toxicology, University of Utah, Salt Lake City, UT
| | - D.K. Takahashi
- Department of Neurology, Stanford University, Palo Alto, CA
| | - J.R. Vargas
- Department of Neurology, University of Utah, Salt Lake City, UT
| | - K.S. Wilcox
- Interdepartmental Program in Neuroscience, University of Utah, Salt Lake City, UT
- Department of Pharmacology & Toxicology, University of Utah, Salt Lake City, UT
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34
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Palumbo O, Mattina T, Palumbo P, Carella M, Perrotta CS. A de novo 11p13 Microduplication in a Patient with Some Features Invoking Silver-Russell Syndrome. Mol Syndromol 2013; 5:11-8. [PMID: 24550760 DOI: 10.1159/000356459] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/02/2013] [Indexed: 01/10/2023] Open
Abstract
Patients with Silver-Russell syndrome (SRS) show an intrauterine and postnatal growth restriction associated with a variable spectrum of additional features. Genetic or epigenetic alterations on chromosomes 7 and 11 can be detected in several SRS patients; however, a large fraction of cases remains with unknown genetic etiology. Here, we describe the clinical and molecular findings of a patient with a phenotype invoking SRS showing intrauterine and postnatal growth retardation, psychomotor retardation, relative macrocephaly, slightly triangular face with pointed chin, clinodactyly, and a slight body asymmetry, in whom single-nucleotide polymorphism oligonucleotide array analysis led to the identification of a de novo 11p13 duplication containing many genes that could be functionally related with the observed clinical features. Many deletions of chromosome 11p13, resulting in WAGR (Wilms tumor, aniridia, genital anomalies, mental retardation) syndrome, have been described, while only few duplications spanning the same region have been reported so far. To our knowledge, this is the first reported case presenting a SRS carrier of an 11p13 duplication. We propose candidate genes for the observed traits, and in particular, we discuss the possible role of the involvement of 2 noncoding RNAs in the etiology of the phenotype.
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Affiliation(s)
- O Palumbo
- Medical Genetics Unit, IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo, Italy
| | - T Mattina
- Department of Pediatrics, Medical Genetics University of Catania, Catania, Italy
| | - P Palumbo
- Medical Genetics Unit, IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo, Italy ; Department of Biology, University of Bari, Bari, Italy
| | - M Carella
- Medical Genetics Unit, IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo, Italy
| | - C S Perrotta
- Medical Genetics Unit, P.O. Vittorio Emanuele III, Gela, Italy
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35
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Boison D, Sandau US, Ruskin DN, Kawamura M, Masino SA. Homeostatic control of brain function - new approaches to understand epileptogenesis. Front Cell Neurosci 2013; 7:109. [PMID: 23882181 PMCID: PMC3712329 DOI: 10.3389/fncel.2013.00109] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Accepted: 06/22/2013] [Indexed: 12/31/2022] Open
Abstract
Neuronal excitability of the brain and ongoing homeostasis depend not only on intrinsic neuronal properties, but also on external environmental factors; together these determine the functionality of neuronal networks. Homeostatic factors become critically important during epileptogenesis, a process that involves complex disruption of self-regulatory mechanisms. Here we focus on the bioenergetic homeostatic network regulator adenosine, a purine nucleoside whose availability is largely regulated by astrocytes. Endogenous adenosine modulates complex network function through multiple mechanisms including adenosine receptor-mediated pathways, mitochondrial bioenergetics, and adenosine receptor-independent changes to the epigenome. Accumulating evidence from our laboratories shows that disruption of adenosine homeostasis plays a major role in epileptogenesis. Conversely, we have found that reconstruction of adenosine's homeostatic functions provides new hope for the prevention of epileptogenesis. We will discuss how adenosine-based therapeutic approaches may interfere with epileptogenesis on an epigenetic level, and how dietary interventions can be used to restore network homeostasis in the brain. We conclude that reconstruction of homeostatic functions in the brain offers a new conceptual advance for the treatment of neurological conditions which goes far beyond current target-centric treatment approaches.
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Affiliation(s)
- Detlev Boison
- Robert Stone Dow Neurobiology Laboratories, Legacy Research Institute Portland, OR, USA
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36
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Seifert G, Steinhäuser C. Neuron–astrocyte signaling and epilepsy. Exp Neurol 2013; 244:4-10. [DOI: 10.1016/j.expneurol.2011.08.024] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Revised: 08/16/2011] [Accepted: 08/25/2011] [Indexed: 12/30/2022]
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37
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Devinsky O, Vezzani A, Najjar S, De Lanerolle NC, Rogawski MA. Glia and epilepsy: excitability and inflammation. Trends Neurosci 2013; 36:174-84. [PMID: 23298414 DOI: 10.1016/j.tins.2012.11.008] [Citation(s) in RCA: 556] [Impact Index Per Article: 50.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2012] [Revised: 11/15/2012] [Accepted: 11/29/2012] [Indexed: 12/26/2022]
Abstract
Epilepsy is characterized by recurrent spontaneous seizures due to hyperexcitability and hypersynchrony of brain neurons. Current theories of pathophysiology stress neuronal dysfunction and damage, and aberrant connections as relevant factors. Most antiepileptic drugs target neuronal mechanisms. However, nearly one-third of patients have seizures that are refractory to available medications; a deeper understanding of mechanisms may be required to conceive more effective therapies. Recent studies point to a significant contribution by non-neuronal cells, the glia--especially astrocytes and microglia--in the pathophysiology of epilepsy. This review critically evaluates the role of glia-induced hyperexcitability and inflammation in epilepsy.
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Affiliation(s)
- Orrin Devinsky
- Epilepsy Center, Department of Neurology, NYU School of Medicine, New York, NY 10016, USA.
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38
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Lin CLG, Kong Q, Cuny GD, Glicksman MA. Glutamate transporter EAAT2: a new target for the treatment of neurodegenerative diseases. Future Med Chem 2012; 4:1689-700. [PMID: 22924507 PMCID: PMC3580837 DOI: 10.4155/fmc.12.122] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Glutamate is the primary excitatory amino acid neurotransmitter in the CNS. The concentration of glutamate in the synaptic cleft is tightly controlled by interplay between glutamate release and glutamate clearance. Abnormal glutamate release and/or dysfunction of glutamate clearance can cause overstimulation of glutamate receptors and result in neuronal injury known as excitotoxicity. The glial glutamate transporter EAAT2 plays a major role in glutamate clearance. Dysfunction or reduced expression of EAAT2 has been documented in many neurodegenerative diseases. In addition, many studies in animal models of disease indicate that increased EAAT2 expression provides neuronal protection. Here, we summarize these studies and suggest that EAAT2 is a potential target for the prevention of excitotoxicity. EAAT2 can be upregulated by transcriptional or translational activation. We discuss current progress in the search for EAAT2 activators, which is a promising direction for the treatment of neurodegenerative diseases.
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Losi G, Cammarota M, Carmignoto G. The role of astroglia in the epileptic brain. Front Pharmacol 2012; 3:132. [PMID: 22807916 PMCID: PMC3395023 DOI: 10.3389/fphar.2012.00132] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Accepted: 06/23/2012] [Indexed: 11/13/2022] Open
Abstract
Epilepsies comprise a family of multifactorial neurological disorders that affect at least 50 million people worldwide. Despite a long history of neurobiological and clinical studies the mechanisms that lead the brain network to a hyperexcitable state and to the intense, massive neuronal discharges reflecting a seizure episode are only partially defined. Most epilepsies of genetic origin are related to mutations in ionic channels that cause neuronal hyperexcitability. However, idiopathic epilepsies of unclear origin represent the majority of these brain disorders. A large body of evidence suggests that in the epileptic brain neurons are not the only players. Indeed, the glial cell astrocyte is known to be morphologically and functionally altered in different types of epilepsy. Although it is unclear whether these astrocyte dysfunctions can have a causative role in epileptogenesis, the hypothesis that astrocytes contribute to epileptiform activities recently received a considerable experimental support. Notably, currently used antiepileptic drugs, that act mainly on neuronal ion channels, are ineffective in a large group of patients. Clarifying astrocyte functions in the epileptic brain tissue could unveil astrocytes as novel therapeutic targets. In this review we present first a short overview on the role of astrocytes in the epileptic brain starting from the "historical" observations on their fundamental modulation of brain homeostasis, such as the control of water content, ionic equilibrium, and neurotransmitters concentrations. We then focus our review on most recent studies that hint at a distinct contribution of these cells in the generation of focal epileptiform activities.
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Affiliation(s)
- Gabriele Losi
- Institute of Neuroscience of the National Research Council and Department of Biomedical Sciences, University of Padova Padova, Italy
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40
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Increased glial glutamate transporter EAAT2 expression reduces epileptogenic processes following pilocarpine-induced status epilepticus. Neurobiol Dis 2012; 47:145-54. [PMID: 22513140 DOI: 10.1016/j.nbd.2012.03.032] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Accepted: 03/24/2012] [Indexed: 11/21/2022] Open
Abstract
Several lines of evidence indicate that glutamate plays a crucial role in the initiation of seizures and their propagation; abnormal glutamate release causes synchronous firing of large populations of neurons, leading to seizures. In the present study, we investigated whether enhanced glutamate uptake by increased glial glutamate transporter EAAT2, the major glutamate transporter, could prevent seizure activity and reduce epileptogenic processes. EAAT2 transgenic mice, which have a 1.5-2 fold increase in EAAT2 protein levels as compared to their non-transgenic counterparts, were tested in a pilocarpine-induced status epilepticus (SE) model. Several striking phenomena were observed in EAAT2 transgenic mice compared with their non-transgenic littermates. First, the post-SE mortality rate and chronic seizure frequency were significantly decreased. Second, neuronal degeneration in hippocampal subfields after SE were significantly reduced. Third, the SE-induced neurogenesis and mossy fiber sprouting were significantly decreased. The severity of cell loss in epileptic mice was positively correlated with that of mossy fiber sprouting and chronic seizure frequency. Our results suggest that increased EAAT2 expression can protect mice against SE-induced death, neuropathological changes, and chronic seizure development. This study suggests that enhancing EAAT2 protein expression is a potential therapeutic approach.
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Luna-Munguia H, Orozco-Suarez S, Rocha L. Effects of high frequency electrical stimulation and R-verapamil on seizure susceptibility and glutamate and GABA release in a model of phenytoin-resistant seizures. Neuropharmacology 2011; 61:807-14. [PMID: 21645533 DOI: 10.1016/j.neuropharm.2011.05.027] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Revised: 05/18/2011] [Accepted: 05/19/2011] [Indexed: 11/30/2022]
Abstract
The present study was focused to characterize the effects of intrahippocampal application of R-verapamil, a P-glycoprotein blocker, and High Frequency Electrical Stimulation (HFS) at 130 Hz, on seizure susceptibility and extracellular concentrations of glutamate and γ-aminobutyric acid (GABA) in hippocampus of kindled rats with drug-resistant seizures. Fully kindled rats classified in responsive and non-responsive to phenytoin were used for this purpose. In contrast with responsive animals, non-responsive rats showed lower afterdischarge threshold (ADT) values in pre-kindling conditions and required less number of kindling trials to achieve the kindled state. Once the animals attained the kindled state, both epileptic groups presented high glutamate and low GABA interictal release, effect more evident in non-responsive rats. In hippocampus of responsive animals, GABA levels demonstrated two increases at 120 and 240 min after the ictal event, a situation no detected for non-responsive rats. Kindled animals receiving hippocampal HFS showed augmented ADT, an effect associated with enhanced GABA release in responsive rats. Intrahippocampal perfusion of R-verapamil (5 mM) decreased the seizure susceptibility (high ADT values), enhanced the interictal GABA release and the postictal levels of glutamate and GABA in responsive and non-responsive rats. It is conclude that alterations of glutamate and GABA release in the epileptic hippocampus of non-responsive animals resemble those found in hippocampus of patients with refractory TLE. In addition, intrahippocampal application of HFS and R-verapamil modifies the amino acid release and reduces the seizure susceptibility of both, responsive and non-responsive rats.
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Affiliation(s)
- Hiram Luna-Munguia
- Department of Pharmacobiology, Center for Research and Advanced Studies, Mexico City, Mexico
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Doi T, Ueda Y, Takaki M, Willmore LJ. Differential molecular regulation of glutamate in kindling resistant rats. Brain Res 2010; 1375:1-6. [PMID: 21138736 DOI: 10.1016/j.brainres.2010.11.085] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2010] [Revised: 11/16/2010] [Accepted: 11/26/2010] [Indexed: 12/13/2022]
Abstract
Using pentylenetetrazol (PTZ) kindling, we collected hippocampal tissue from standard response and kindling resistant animals, measuring hippocampal mRNA with real-time PCR of glutamate transporters GLAST, GLT-1, and EAAC1 and the sodium-coupled neutral amino acid transporter (SNAT) 1, SNAT2, and SNAT3. In addition, we measured mRNA of glutamine synthetase (GS), phosphate-activated glutaminase (PAG), glutamic acid decarboxylase (GAD) 1, GAD2, and vesicular inhibitory amino acid transporter (VIAAT). Fully kindled animals had decreased expression of mRNA in the hippocampus for GLAST and GAD2 compared with saline injected control. mRNA for SNAT1, SNAT2, SNAT3, GS, and VIAAT was increased. After induction of generalized tonic-clonic seizures by PTZ there were no differences in mRNA at 24h after seizures, equaling baseline quantities except for GAD1, which was decreased. When levels were measured at 30days after a PTZ induced convulsive seizure, we found increased levels of GLT-1, SNAT1 and GS, but decreased levels of GAD1. When these animals, serving as control for the 30day interval between the last convulsive seizure in the kindled experimental group, were analyzed, we found that GLT-1, SNAT3, GAD1 and VIAAT differed in that GLT-1 was decreased and the others increased. Animals found resistant to kindling had strikingly different mRNA patterns, with markedly up-regulated mRNA of proteins that transport glutamate into neurons and glia; SNAT1 was up regulated as well. Up-regulation of genes in kindling resistant animals supports the hypothesis that clearance of glutamate, conversion to glutamine and transport of glutamine into neurons, has the effect of raising the threshold for convulsive seizures and attenuating kindling.
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Affiliation(s)
- Taku Doi
- Section of Psychiatry, Department of Clinical Neuroscience, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki, 889-1692, Japan.
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Wu L, Peng J, Wei C, Liu G, Wang G, Li K, Yin F. Characterization, using comparative proteomics, of differentially expressed proteins in the hippocampus of the mesial temporal lobe of epileptic rats following treatment with valproate. Amino Acids 2010; 40:221-38. [PMID: 20524136 DOI: 10.1007/s00726-010-0638-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2009] [Accepted: 05/19/2010] [Indexed: 12/13/2022]
Abstract
The objective of the study was to explore the pathogenesis of mesial temporal lobe epilepsy (MTLE) and the mechanism of valproate administration in the early stage of MTLE development. We performed a global comparative analysis and function classification of differentially expressed proteins using proteomics. MTLE models of developmental rats were induced by lithium-pilocarpine. Proteins in the hippocampus were separated by 2-DE technology. PDQuest software was used to analyze 2-DE images, and MALDI-TOF-MS was used to identify the differentially expressed proteins. Western blot was used to determine the differential expression levels of synapse-related proteins synapsin-1, dynamin-1 and neurogranin in both MTLE rat and human hippocampus. A total of 48 differentially expressed proteins were identified between spontaneous and non-spontaneous MTLE rats, while 41 proteins between MTLE rats and post valproate-treatment rats were identified. All of the proteins can be categorized into several groups by biological functions: synaptic and neurotransmitter release, cytoskeletal structure and dynamics, cell junctions, energy metabolism and mitochondrial function, molecular chaperones, signal regulation and others. Western blot results were similar to the changes noted in 2-DE. The differentially expressed proteins, especially the proteins related to synaptic and neurotransmitter release function, such as synapsin-1, dynamin-1 and neurogranin, are probably involved in the mechanism of MTLE and the pharmacological effect of valproate. These findings may provide important clues to elucidate the mechanism of chronic MTLE and to identify an optimum medication intervention time and new biomarkers for the development of pharmacological therapies targeted at epilepsy.
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Affiliation(s)
- Liwen Wu
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha 410008, Hunan, People's Republic of China
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Astrocyte dysfunction in epilepsy. ACTA ACUST UNITED AC 2010; 63:212-21. [DOI: 10.1016/j.brainresrev.2009.10.004] [Citation(s) in RCA: 194] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2009] [Revised: 10/23/2009] [Accepted: 10/27/2009] [Indexed: 12/18/2022]
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