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Gong L, Liang J, Xie L, Zhang Z, Mei Z, Zhang W. Metabolic Reprogramming in Gliocyte Post-cerebral Ischemia/ Reperfusion: From Pathophysiology to Therapeutic Potential. Curr Neuropharmacol 2024; 22:1672-1696. [PMID: 38362904 DOI: 10.2174/1570159x22666240131121032] [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: 08/21/2023] [Revised: 12/08/2023] [Accepted: 12/13/2023] [Indexed: 02/17/2024] Open
Abstract
Ischemic stroke is a leading cause of disability and death worldwide. However, the clinical efficacy of recanalization therapy as a preferred option is significantly hindered by reperfusion injury. The transformation between different phenotypes of gliocytes is closely associated with cerebral ischemia/ reperfusion injury (CI/RI). Moreover, gliocyte polarization induces metabolic reprogramming, which refers to the shift in gliocyte phenotype and the overall transformation of the metabolic network to compensate for energy demand and building block requirements during CI/RI caused by hypoxia, energy deficiency, and oxidative stress. Within microglia, the pro-inflammatory phenotype exhibits upregulated glycolysis, pentose phosphate pathway, fatty acid synthesis, and glutamine synthesis, whereas the anti-inflammatory phenotype demonstrates enhanced mitochondrial oxidative phosphorylation and fatty acid oxidation. Reactive astrocytes display increased glycolysis but impaired glycogenolysis and reduced glutamate uptake after CI/RI. There is mounting evidence suggesting that manipulation of energy metabolism homeostasis can induce microglial cells and astrocytes to switch from neurotoxic to neuroprotective phenotypes. A comprehensive understanding of underlying mechanisms and manipulation strategies targeting metabolic pathways could potentially enable gliocytes to be reprogrammed toward beneficial functions while opening new therapeutic avenues for CI/RI treatment. This review provides an overview of current insights into metabolic reprogramming mechanisms in microglia and astrocytes within the pathophysiological context of CI/RI, along with potential pharmacological targets. Herein, we emphasize the potential of metabolic reprogramming of gliocytes as a therapeutic target for CI/RI and aim to offer a novel perspective in the treatment of CI/RI.
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Affiliation(s)
- Lipeng Gong
- Key Laboratory of Hunan Province for Integrated Traditional Chinese and Western Medicine on Prevention and Treatment of Cardio-Cerebral Diseases, College of Integrated Traditional Chinese Medicine and Western Medicine, Hunan University of Chinese Medicine, Changsha, Hunan 410208, China
| | - Junjie Liang
- Key Laboratory of Hunan Province for Integrated Traditional Chinese and Western Medicine on Prevention and Treatment of Cardio-Cerebral Diseases, College of Integrated Traditional Chinese Medicine and Western Medicine, Hunan University of Chinese Medicine, Changsha, Hunan 410208, China
| | - Letian Xie
- Key Laboratory of Hunan Province for Integrated Traditional Chinese and Western Medicine on Prevention and Treatment of Cardio-Cerebral Diseases, College of Integrated Traditional Chinese Medicine and Western Medicine, Hunan University of Chinese Medicine, Changsha, Hunan 410208, China
| | - Zhanwei Zhang
- Department of Neurosurgery, First Affiliated Hospital of Hunan University of Traditional Chinese Medicine, Changsha, Hunan 410007, China
| | - Zhigang Mei
- Key Laboratory of Hunan Province for Integrated Traditional Chinese and Western Medicine on Prevention and Treatment of Cardio-Cerebral Diseases, College of Integrated Traditional Chinese Medicine and Western Medicine, Hunan University of Chinese Medicine, Changsha, Hunan 410208, China
- Third-Grade Pharmacological Laboratory on Chinese Medicine Approved by State Administration of Traditional Chinese Medicine, College of Medicine and Health Sciences, China Three Gorges University, Yichang, Hubei 443002, China
| | - Wenli Zhang
- School of Pharmacy, Hunan University of Chinese Medicine, Changsha, Hunan 410208, China
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Fan Y, Huang H, Shao J, Huang W. MicroRNA-mediated regulation of reactive astrocytes in central nervous system diseases. Front Mol Neurosci 2023; 15:1061343. [PMID: 36710937 PMCID: PMC9877358 DOI: 10.3389/fnmol.2022.1061343] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Accepted: 12/22/2022] [Indexed: 01/15/2023] Open
Abstract
Astrocytes (AST) are abundant glial cells in the human brain, accounting for approximately 20-50% percent of mammalian central nervous system (CNS) cells. They display essential functions necessary to sustain the physiological processes of the CNS, including maintaining neuronal structure, forming the blood-brain barrier, coordinating neuronal metabolism, maintaining the extracellular environment, regulating cerebral blood flow, stabilizing intercellular communication, participating in neurotransmitter synthesis, and defending against oxidative stress et al. During the pathological development of brain tumors, stroke, spinal cord injury (SCI), neurodegenerative diseases, and other neurological disorders, astrocytes undergo a series of highly heterogeneous changes, which are called reactive astrocytes, and mediate the corresponding pathophysiological process. However, the pathophysiological mechanisms of reactive astrocytes and their therapeutic relevance remain unclear. The microRNAs (miRNAs) are essential for cell differentiation, proliferation, and survival, which play a crucial role in the pathophysiological development of CNS diseases. In this review, we summarize the regulatory mechanism of miRNAs on reactive astrocytes in CNS diseases, which might provide a theoretical basis for the diagnosis and treatment of CNS diseases.
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Zong P, Yue L. Regulation of Presynaptic Calcium Channels. ADVANCES IN NEUROBIOLOGY 2023; 33:171-202. [PMID: 37615867 DOI: 10.1007/978-3-031-34229-5_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Abstract
Voltage-gated calcium channels (VGCCs), especially Cav2.1 and Cav2.2, are the major mediators of Ca2+ influx at the presynaptic membrane in response to neuron excitation, thereby exerting a predominant control on synaptic transmission. To guarantee the timely and precise release of neurotransmitters at synapses, the activity of presynaptic VGCCs is tightly regulated by a variety of factors, including auxiliary subunits, membrane potential, G protein-coupled receptors (GPCRs), calmodulin (CaM), Ca2+-binding proteins (CaBP), protein kinases, various interacting proteins, alternative splicing events, and genetic variations.
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Affiliation(s)
- Pengyu Zong
- Department of Cell Biology, Calhoun Cardiology Center, University of Connecticut School of Medicine, Farmington, CT, USA
| | - Lixia Yue
- Department of Cell Biology, Calhoun Cardiology Center, University of Connecticut School of Medicine, Farmington, CT, USA.
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Zong P, Lin Q, Feng J, Yue L. A Systemic Review of the Integral Role of TRPM2 in Ischemic Stroke: From Upstream Risk Factors to Ultimate Neuronal Death. Cells 2022; 11:491. [PMID: 35159300 PMCID: PMC8834171 DOI: 10.3390/cells11030491] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Revised: 01/26/2022] [Accepted: 01/29/2022] [Indexed: 02/04/2023] Open
Abstract
Ischemic stroke causes a heavy health burden worldwide, with over 10 million new cases every year. Despite the high prevalence and mortality rate of ischemic stroke, the underlying molecular mechanisms for the common etiological factors of ischemic stroke and ischemic stroke itself remain unclear, which results in insufficient preventive strategies and ineffective treatments for this devastating disease. In this review, we demonstrate that transient receptor potential cation channel, subfamily M, member 2 (TRPM2), a non-selective ion channel activated by oxidative stress, is actively involved in all the important steps in the etiology and pathology of ischemic stroke. TRPM2 could be a promising target in screening more effective prophylactic strategies and therapeutic medications for ischemic stroke.
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Affiliation(s)
- Pengyu Zong
- Department of Cell Biology, Calhoun Cardiology Center, University of Connecticut School of Medicine (UConnHealth), Farmington, CT 06030, USA; (P.Z.); (J.F.)
| | - Qiaoshan Lin
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT 06269, USA;
| | - Jianlin Feng
- Department of Cell Biology, Calhoun Cardiology Center, University of Connecticut School of Medicine (UConnHealth), Farmington, CT 06030, USA; (P.Z.); (J.F.)
| | - Lixia Yue
- Department of Cell Biology, Calhoun Cardiology Center, University of Connecticut School of Medicine (UConnHealth), Farmington, CT 06030, USA; (P.Z.); (J.F.)
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Glial Cells as Therapeutic Approaches in Brain Ischemia-Reperfusion Injury. Cells 2021; 10:cells10071639. [PMID: 34208834 PMCID: PMC8305833 DOI: 10.3390/cells10071639] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Revised: 06/24/2021] [Accepted: 06/26/2021] [Indexed: 02/07/2023] Open
Abstract
Ischemic stroke is the second cause of mortality and the first cause of long-term disability constituting a serious socioeconomic burden worldwide. Approved treatments include thrombectomy and rtPA intravenous administration, which, despite their efficacy in some cases, are not suitable for a great proportion of patients. Glial cell-related therapies are progressively overcoming inefficient neuron-centered approaches in the preclinical phase. Exploiting the ability of microglia to naturally switch between detrimental and protective phenotypes represents a promising therapeutic treatment, in a similar way to what happens with astrocytes. However, the duality present in many of the roles of these cells upon ischemia poses a notorious difficulty in disentangling the precise pathways to target. Still, promoting M2/A2 microglia/astrocyte protective phenotypes and inhibiting M1/A1 neurotoxic profiles is globally rendering promising results in different in vivo models of stroke. On the other hand, described oligodendrogenesis after brain ischemia seems to be strictly beneficial, although these cells are the less studied players in the stroke paradigm and negative effects could be described for oligodendrocytes in the next years. Here, we review recent advances in understanding the precise role of mentioned glial cell types in the main pathological events of ischemic stroke, including inflammation, blood brain barrier integrity, excitotoxicity, reactive oxygen species management, metabolic support, and neurogenesis, among others, with a special attention to tested therapeutic approaches.
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Alhaddad H, Alasmari F, Alhamadani B, Wong W, Bell RL, Sari Y. Effects of chronic ethanol consumption on the expression of GLT-1 and neuroplasticity-related proteins in the nucleus accumbens of alcohol-preferring rats. Brain Res Bull 2020; 165:272-280. [PMID: 33075417 DOI: 10.1016/j.brainresbull.2020.10.012] [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: 08/13/2020] [Revised: 09/25/2020] [Accepted: 10/09/2020] [Indexed: 11/26/2022]
Abstract
Chronic ethanol exposure induces impairments in CNS excitatory and inhibitory activity. These impairments are associated with glutamatergic dysfunction, including altered neuroplasticity. This study examined the effects of 6-week ethanol (15% and 30% v/v) consumption, by male alcohol-preferring P rats, on protein expression associated with neuroplasticity and glutamate transporter-1 (GLT-1) function. The latter regulates intra- and extra-synaptic glutamate levels. We focused on the shell and core subregions of the nucleus accumbens (Acb); i.e., shell (AcbSh) and core (AcbCo), for these measures. Chronic ethanol exposure increased the expression of BDNF, Arc and phosphorylated (p)-post-synaptic density protein-95 (p-PSD-95) in the AcbSh of P rats. Moreover, the ratio of phospho-neuronal nitric oxide synthase (p-nNOS) to total nNOS was also increased in the AcbSh. These changes in BDNF, Arc and p-nNOS/nNOS ratio were not observed in the AcbCo. Furthermore, chronic ethanol consumption reduced GLT-1 expression in the AcbSh. Alternatively, treatment with ceftriaxone (CEF), a known GLT-1 upregulator, abolished the effect of chronic ethanol consumption on BDNF expression in the AcbSh. Overall, the present findings confirm that chronic ethanol consumption modulates activity-associated synaptic proteins, including BDNF, Arc and nNOS in a subregion-specific (i.e., in the AcbSh but not AcbCo) manner. Thus, alterations in mesocorticolimbic glutamatergic homeostasis and neuroplasticity are possible functional targets for the treatment of alcohol use disorders.
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Affiliation(s)
- Hasan Alhaddad
- University of Toledo, College of Pharmacy and Pharmaceutical Sciences, Department of Pharmacology and Experimental Therapeutics, Toledo, OH 43614, USA
| | - Fawaz Alasmari
- University of Toledo, College of Pharmacy and Pharmaceutical Sciences, Department of Pharmacology and Experimental Therapeutics, Toledo, OH 43614, USA; Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia
| | - Balsam Alhamadani
- University of Toledo, College of Pharmacy and Pharmaceutical Sciences, Department of Pharmacology and Experimental Therapeutics, Toledo, OH 43614, USA
| | - Woonyen Wong
- University of Toledo, College of Pharmacy and Pharmaceutical Sciences, Department of Pharmacology and Experimental Therapeutics, Toledo, OH 43614, USA
| | - Richard L Bell
- Department of Psychiatry and Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
| | - Youssef Sari
- University of Toledo, College of Pharmacy and Pharmaceutical Sciences, Department of Pharmacology and Experimental Therapeutics, Toledo, OH 43614, USA.
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Chen Y, Qin C, Huang J, Tang X, Liu C, Huang K, Xu J, Guo G, Tong A, Zhou L. The role of astrocytes in oxidative stress of central nervous system: A mixed blessing. Cell Prolif 2020; 53:e12781. [PMID: 32035016 PMCID: PMC7106951 DOI: 10.1111/cpr.12781] [Citation(s) in RCA: 143] [Impact Index Per Article: 35.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Revised: 12/17/2019] [Accepted: 01/20/2020] [Indexed: 02/05/2023] Open
Abstract
Central nervous system (CNS) maintains a high level of metabolism, which leads to the generation of large amounts of free radicals, and it is also one of the most vulnerable organs to oxidative stress. Emerging evidences have shown that, as the key homeostatic cells in CNS, astrocytes are deeply involved in multiple aspects of CNS function including oxidative stress regulation. Besides, the redox level in CNS can in turn affect astrocytes in morphology and function. The complex and multiple roles of astrocytes indicate that their correct performance is crucial for the normal functioning of the CNS, and its dysfunction may result in the occurrence and progression of various neurological disorders. To date, the influence of astrocytes in CNS oxidative stress is rarely reviewed. Therefore, in this review we sum up the roles of astrocytes in redox regulation and the corresponding mechanisms under both normal and different pathological conditions.
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Affiliation(s)
- Yaxing Chen
- Department of Neurosurgery, West China Medical School, West China Hospital, Sichuan University, Chengdu, China
| | - Chen Qin
- Department of Neurosurgery, West China Medical School, West China Hospital, Sichuan University, Chengdu, China
| | - Jianhan Huang
- Department of Neurosurgery, West China Medical School, West China Hospital, Sichuan University, Chengdu, China
| | - Xin Tang
- Department of Neurosurgery, West China Medical School, West China Hospital, Sichuan University, Chengdu, China
| | - Chang Liu
- Department of Neurosurgery, West China Medical School, West China Hospital, Sichuan University, Chengdu, China
| | - Keru Huang
- Department of Neurosurgery, West China Medical School, West China Hospital, Sichuan University, Chengdu, China
| | - Jianguo Xu
- Department of Neurosurgery, West China Medical School, West China Hospital, Sichuan University, Chengdu, China
| | - Gang Guo
- State Key Laboratory of Biotherapy, West China Medical School, Sichuan University, Chengdu, China
| | - Aiping Tong
- State Key Laboratory of Biotherapy, West China Medical School, Sichuan University, Chengdu, China
| | - Liangxue Zhou
- Department of Neurosurgery, West China Medical School, West China Hospital, Sichuan University, Chengdu, China
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Pajarillo E, Rizor A, Lee J, Aschner M, Lee E. The role of astrocytic glutamate transporters GLT-1 and GLAST in neurological disorders: Potential targets for neurotherapeutics. Neuropharmacology 2019; 161:107559. [PMID: 30851309 PMCID: PMC6731169 DOI: 10.1016/j.neuropharm.2019.03.002] [Citation(s) in RCA: 202] [Impact Index Per Article: 40.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2018] [Revised: 02/28/2019] [Accepted: 03/02/2019] [Indexed: 12/12/2022]
Abstract
Glutamate is the primary excitatory neurotransmitter in the central nervous system (CNS) which initiates rapid signal transmission in the synapse before its re-uptake into the surrounding glia, specifically astrocytes. The astrocytic glutamate transporters glutamate-aspartate transporter (GLAST) and glutamate transporter-1 (GLT-1) and their human homologs excitatory amino acid transporter 1 (EAAT1) and 2 (EAAT2), respectively, are the major transporters which take up synaptic glutamate to maintain optimal extracellular glutamic levels, thus preventing accumulation in the synaptic cleft and ensuing excitotoxicity. Growing evidence has shown that excitotoxicity is associated with various neurological disorders, including amyotrophic lateral sclerosis (ALS), Alzheimer's disease (AD), Parkinson's disease (PD), manganism, ischemia, schizophrenia, epilepsy, and autism. While the mechanisms of neurological disorders are not well understood, the dysregulation of GLAST/GLT-1 may play a significant role in excitotoxicity and associated neuropathogenesis. The expression and function of GLAST/GLT-1 may be dysregulated at the genetic, epigenetic, transcriptional or translational levels, leading to high levels of extracellular glutamate and excitotoxicity. Consequently, understanding the regulatory mechanisms of GLAST/GLT-1 has been an area of interest in developing therapeutics for the treatment of neurological disorders. Pharmacological agents including β-lactam antibiotics, estrogen/selective estrogen receptor modulators (SERMs), growth factors, histone deacetylase inhibitors (HDACi), and translational activators have shown significant efficacy in enhancing the expression and function of GLAST/GLT-1 and glutamate uptake both in vitro and in vivo. This comprehensive review will discuss the regulatory mechanisms of GLAST/GLT-1, their association with neurological disorders, and the pharmacological agents which mediate their expression and function. This article is part of the issue entitled 'Special Issue on Neurotransmitter Transporters'.
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Affiliation(s)
- Edward Pajarillo
- Department of Pharmaceutical Sciences, College of Pharmacy, Florida A&M University, Tallahassee, FL, 32301, USA
| | - Asha Rizor
- Department of Pharmaceutical Sciences, College of Pharmacy, Florida A&M University, Tallahassee, FL, 32301, USA
| | - Jayden Lee
- Department of Speech, Language & Hearing Sciences, Boston University, Boston, MA, 02215, USA
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Eunsook Lee
- Department of Pharmaceutical Sciences, College of Pharmacy, Florida A&M University, Tallahassee, FL, 32301, USA.
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Peters M, Wielsch B, Boltze J. The role of SUMOylation in cerebral hypoxia and ischemia. Neurochem Int 2017; 107:66-77. [DOI: 10.1016/j.neuint.2017.03.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Revised: 03/09/2017] [Accepted: 03/15/2017] [Indexed: 10/19/2022]
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David CN, Frias ES, Szu JI, Vieira PA, Hubbard JA, Lovelace J, Michael M, Worth D, McGovern KE, Ethell IM, Stanley BG, Korzus E, Fiacco TA, Binder DK, Wilson EH. GLT-1-Dependent Disruption of CNS Glutamate Homeostasis and Neuronal Function by the Protozoan Parasite Toxoplasma gondii. PLoS Pathog 2016; 12:e1005643. [PMID: 27281462 PMCID: PMC4900626 DOI: 10.1371/journal.ppat.1005643] [Citation(s) in RCA: 92] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Accepted: 04/28/2016] [Indexed: 01/09/2023] Open
Abstract
The immune privileged nature of the CNS can make it vulnerable to chronic and latent infections. Little is known about the effects of lifelong brain infections, and thus inflammation, on the neurological health of the host. Toxoplasma gondii is a parasite that can infect any mammalian nucleated cell with average worldwide seroprevalence rates of 30%. Infection by Toxoplasma is characterized by the lifelong presence of parasitic cysts within neurons in the brain, requiring a competent immune system to prevent parasite reactivation and encephalitis. In the immunocompetent individual, Toxoplasma infection is largely asymptomatic, however many recent studies suggest a strong correlation with certain neurodegenerative and psychiatric disorders. Here, we demonstrate a significant reduction in the primary astrocytic glutamate transporter, GLT-1, following infection with Toxoplasma. Using microdialysis of the murine frontal cortex over the course of infection, a significant increase in extracellular concentrations of glutamate is observed. Consistent with glutamate dysregulation, analysis of neurons reveal changes in morphology including a reduction in dendritic spines, VGlut1 and NeuN immunoreactivity. Furthermore, behavioral testing and EEG recordings point to significant changes in neuronal output. Finally, these changes in neuronal connectivity are dependent on infection-induced downregulation of GLT-1 as treatment with the ß-lactam antibiotic ceftriaxone, rescues extracellular glutamate concentrations, neuronal pathology and function. Altogether, these data demonstrate that following an infection with T. gondii, the delicate regulation of glutamate by astrocytes is disrupted and accounts for a range of deficits observed in chronic infection. The protozoan parasite Toxoplasma gondii infects a third of the world’s population and causes a chronic lifelong infection in the brain of the host. The consequences of such an infection are poorly understood. Here, we demonstrate that Toxoplasma infection can induce profound changes in astrocyte physiology leading to significant disruption of neuronal networks. Pathology can be rescued by upregulating the astrocytic glutamate transporter, GLT-1, restoring concentrations of extracellular glutamate and EEG power. We suggest that such global dysregulation of neurotransmitters should be considered when determining the effects of infection on the CNS.
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Affiliation(s)
- Clément N. David
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, California, United States of America
| | - Elma S. Frias
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, California, United States of America
| | - Jenny I. Szu
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, California, United States of America
| | - Philip A. Vieira
- Department of Psychology, University of California, Riverside, Riverside, California, United States of America
| | - Jacqueline A. Hubbard
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, California, United States of America
| | - Jonathan Lovelace
- Department of Psychology, University of California, Riverside, Riverside, California, United States of America
| | - Marena Michael
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, California, United States of America
| | - Danielle Worth
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, California, United States of America
| | - Kathryn E. McGovern
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, California, United States of America
| | - Iryna M. Ethell
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, California, United States of America
| | - B. Glenn Stanley
- Department of Psychology, University of California, Riverside, Riverside, California, United States of America
| | - Edward Korzus
- Department of Psychology, University of California, Riverside, Riverside, California, United States of America
| | - Todd A. Fiacco
- Department of Neuroscience, University of California, Riverside, Riverside, California, United States of America
| | - Devin K. Binder
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, California, United States of America
| | - Emma H. Wilson
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, California, United States of America
- * E-mail:
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Liang J, Chao D, Sandhu HK, Yu Y, Zhang L, Balboni G, Kim DH, Xia Y. δ-Opioid receptors up-regulate excitatory amino acid transporters in mouse astrocytes. Br J Pharmacol 2015; 171:5417-30. [PMID: 25052197 DOI: 10.1111/bph.12857] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2013] [Revised: 07/07/2014] [Accepted: 07/17/2014] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND AND PURPOSE Astrocytic excitatory amino acid transporters (EAATs) regulate extracellular glutamate concentrations and play a role in preventing neuroexcitotoxicity. As the δ-opioid receptor (DOP receptor) is neuroprotective against excitotoxic injury, we determined whether DOP receptor activation up-regulates EAAT expression and function. EXPERIMENTAL APPROACH We measured mRNA and protein expression of EAAT1, EAAT2 and EAAT3 in cultured mouse astrocytes exposed to a specific DOP receptor agonist (UFP-512) with or without a DOP receptor antagonist, DOP receptor siRNA or inhibitors of PKC, PKA, PI3K, p38, MAPK, MEK and ERK, and evaluated the function of EAATs by measuring glutamate uptake. KEY RESULTS Astrocytic DOP receptor mRNA and protein were suppressed by DOP receptor siRNA knockdown. DOP receptor activation increased mRNA and protein expression of EAAT1 and EAAT2, but not EAAT3, thereby enhancing glutamate uptake of astrocytes. DOP receptor-induced EAAT1 and EAAT2 expression was largely reversed by DOP receptor antagonist naltrindole or by DOP receptor siRNA knockdown, and suppressed by inhibitors of MEK, ERK and p38. DOP receptor-accelerated glutamate uptake was inhibited by EAAT blockers, DOP receptor siRNA knockdown or inhibitors of MEK, ERK or p38. In contrast, inhibitors of PKA, PKC or PI3K had no significant effect on DOP receptor-induced EAAT expression. CONCLUSIONS AND IMPLICATIONS DOP receptor activation up-regulates astrocytic EAATs via MEK-ERK-p38 signalling, suggesting a critical role for DOP receptors in the regulation of astrocytic EAATs and protection against neuroexcitotoxicity. As decreased EAAT expression contributes to pathophysiology in many neurological diseases, including amyotrophic lateral sclerosis, our findings present a new platform for potential treatments of these diseases.
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Affiliation(s)
- Jianfeng Liang
- Department of Neurosurgery, The University of Texas Medical School at Houston, Houston, TX, USA; Yale University School of Medicine, New Haven, CT, USA; Department of Neurosurgery, China-Japan Friendship Hospital, Beijing, China
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N-Methyl-d-aspartate Preconditioning Prevents Quinolinic Acid-Induced Deregulation of Glutamate and Calcium Homeostasis in Mice Hippocampus. Neurotox Res 2014; 27:118-28. [DOI: 10.1007/s12640-014-9496-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Revised: 09/30/2014] [Accepted: 10/15/2014] [Indexed: 10/24/2022]
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Sakurai M, Kurokawa H, Shimada A, Nakamura K, Miyata H, Morita T. Excitatory amino acid transporter 2 downregulation correlates with thalamic neuronal death following kainic acid-induced status epilepticus in rat. Neuropathology 2014; 35:1-9. [PMID: 25059512 DOI: 10.1111/neup.12141] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2014] [Accepted: 05/15/2014] [Indexed: 11/28/2022]
Abstract
Recurrent seizures without interictal resumption (status epilepticus) have been reported to induce neuronal death in the midline thalamic region that has functional roles in memory and decision-making; however, the pathogenesis underlying status epilepticus-induced thalamic neuronal death is yet to be determined. We performed histological and immunohistochemical studies as well as cerebral blood flow measurement using 4.7 tesla magnetic resonance imaging spectrometer on midline thalamic region in Sprague-Dawley rats (n = 75, male, 7 weeks after birth, body weight 250-300 g) treated with intraperitoneal injection of kainic acid (10 mg/kg) to induce status epilepticus (n = 55) or normal saline solution (n = 20). Histological study using paraffin-embedded specimens revealed neuronal death showing ischemic-like changes and Fluoro-Jade C positivity with calcium deposition in the midline thalamic region of epileptic rats. The distribution of neuronal death was associated with focal loss of immunoreactivity for excitatory amino acid transporter 2 (EAAT2), stronger immunoreaction for glutamate and increase in number of Iba-1-positive microglial cells showing swollen cytoplasm and long processes. Double immunofluorescence study demonstrated co-expression of interleukin-1 beta (IL-1β) and inducible nitric oxide synthase (iNOS) within microglial cells, and loss of EAAT2 immunoreactivity in reactive astrocytes. These microglial alterations and astrocytic EAAT2 downregulation were also observed in tissue without obvious neuronal death in kainic acid-treated rats. These results suggest the possible role of glutamate excitotoxicity in neuronal death in the midline thalamic region following kainic acid-induced status epilepticus due to astrocytic EAAT2 downregulation following microglial activation showing upregulation of IL-1β and iNOS.
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Affiliation(s)
- Masashi Sakurai
- Department of Veterinary Pathology, Tottori University, Tottori, Japan
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Yatomi Y, Tanaka R, Shimura H, Miyamoto N, Yamashiro K, Takanashi M, Urabe T, Hattori N. Chronic brain ischemia induces the expression of glial glutamate transporter EAAT2 in subcortical white matter. Neuroscience 2013; 244:113-21. [PMID: 23602887 DOI: 10.1016/j.neuroscience.2013.04.018] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Accepted: 04/02/2013] [Indexed: 01/11/2023]
Abstract
Glutamate plays a central role in brain physiology and pathology. The involvement of excitatory amino acid transporters (EAATs) in neurodegenerative disorders including acute stroke has been widely studied, but little is known about the role of glial glutamate transporters in white matter injury after chronic cerebral hypoperfusion. The present study evaluated the expression of glial (EAAT1 and EAAT2) and neuronal (EAAT3) glutamate transporters in subcortical white matter and cortex, before and 3-28 days after the ligation of bilateral common carotid arteries (LBCCA) in rat brain. K-B staining showed a gradual increase of demyelination in white matter after ischemia, while there was no cortical involvement. Between 3 and 7 days after LBCCA, a significant increase in EAAT2 protein levels was observed in the ischemic brain and the number of EAAT2-positive cells also significantly increased both in the cortical and white matter lesions. EAAT2 was detected in glial-fibrillary acidic protein (GFAP)-positive astrocytes in both the cortex and white matter, but not in neuronal and oligodendroglial cells. EAAT1 was slightly elevated after ischemia only in the white matter, but EAAT3 was at almost similar levels both in the cortex and white matter after ischemia. A significant increase in EAAT2 expression level was also noted in the deep white matter of chronic human ischemic brain tissue compared to the control group. Our findings suggest important roles for up-regulated EAAT2 in chronic brain ischemia especially in the regulation of high-affinity of extracellular glutamate and minimization of white matter damage.
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Affiliation(s)
- Y Yatomi
- Department of Neurology, Juntendo University School of Medicine, Tokyo, Japan
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Spatio-temporal spread of neuronal death after focal photolysis of caged glutamate in neuron/astrocyte co-cultures. Neurochem Int 2013; 62:1020-7. [PMID: 23538265 DOI: 10.1016/j.neuint.2013.03.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Revised: 03/13/2013] [Accepted: 03/15/2013] [Indexed: 11/22/2022]
Abstract
Glutamate-mediated excitotoxicity is now accepted as a major mechanism of ischemic neuronal damage. In the infarct core region, massive neuronal death is observed, but neurons in the surroundings of the core (ischemic penumbra) seem viable at the time of stroke. Several hours or days after a stroke, however, many neurons in the penumbra will undergo delayed neuronal death (DND). The mechanisms responsible for such DND are not fully understood. In this study, we investigated whether and how glutamate-mediated localized excitotoxic neuronal death affects surrounding neurons and astrocytes. To induce spatially-restricted excitotoxic neuronal death, a caged glutamate was focally photolyzed by a UV flash in neuron/astrocyte co-cultures. Uncaging of the glutamate resulted in acute neuronal death in the flashed area. After that, DND was observed in the surroundings of the flashed area late after the uncaging. In contrast, DND was not observed in neuron-enriched cultures, suggesting that functional changes in astrocytes, not neurons, after focal acute neuronal death were involved in the induction of DND. The present in vitro study showed that the spatially-restricted excitotoxic neuronal death resulted in DND in the surroundings of the flashed area, and suggested that the nitric oxide (NO)-induced reduction in the expression of astrocytic GLT-1 was responsible for the occurrence of the DND.
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Zhou J, Wu PF, Wang F, Chen JG. Targeting gaseous molecules to protect against cerebral ischaemic injury: mechanisms and prospects. Clin Exp Pharmacol Physiol 2013; 39:566-76. [PMID: 22150768 DOI: 10.1111/j.1440-1681.2011.05654.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
1. Ischaemic brain injury is a leading cause of death and disability in many countries. However, the pathological mechanisms underlying ischaemic brain injury, including oxidative stress, calcium overload, excitotoxicity and neuronal apoptosis, are perplexing and this makes it difficult to find effective novel drugs for the treatment of the condition. 2. Recently, gaseous molecules such as nitric oxide (NO), carbon monoxide (CO), hydrogen sulphide (H(2)S) and hydrogen (H(2)) have attracted considerable interest because of their physiological and pathophysiological roles in various body systems. Emerging evidence indicates that gaseous molecules are involved in the pathological processes of ischaemic brain damage. 3. In the present review, we summarize evidence regarding the involvement of gaseous molecules in ischaemic brain injury and discuss the therapeutic potential of targeting gaseous molecules. 4. Collectively, the available data suggest that the application of these biological gas molecules and their pharmacological regulators may be a potential therapeutic approach for the treatment of ischaemic brain injury.
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Affiliation(s)
- Jun Zhou
- Department of Pharmacology, Tongji Medical College, Huazhong University of Science and Technology, #13 Hangkong Road, Wuhan, Hubei 430030, China
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Wu X, Zhou C, Du F, Lu Y, Peng B, Chen L, Zhu L. Ginkgolide B preconditioning on astrocytes promotes neuronal survival in ischemic injury via up-regulating erythropoietin secretion. Neurochem Int 2012. [PMID: 23201340 DOI: 10.1016/j.neuint.2012.11.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Although ischemic preconditioning (IP) can provide powerful protection on brain against ischemic insult, it is rarely used in clinic to prevent the occurrence of ischemic stroke because of safety concerns. It is therefore necessary to seek the safer stimuli to initiate pharmacological preconditioning. Our previous work demonstrated that ginkgolide B (GB) could protect neurons against ischemia-induced apoptosis. Astrocytes are the most numerous cells in mammalian central nervous system and there is a close bi-directional communication between neurons and astrocytes in brain. Besides neurons, whether GB can exert the role of preconditioning on astrocytes through which to further improve neuronal survival under ischemic condition is not yet known. In the present study, primary cultured astrocytes were treated with GB for 24h or short-term ischemia (ischemia for 3h, as ischemic preconditioning/IP), and then cultured back to normoxia and normal medium for 24h to induce the preconditioning response. Astrocyte-conditioned medium (ACM) was then collected and used to incubate the cultured neurons for 24h before neurons were subjected to severe ischemia. Our results demonstrated that not only GB and IP increased astrocytic viability in ischemia, but also the conditioned medium from astrocytes treated with GB or IP increased cell viability and decreased the number of apoptosis of neurons in ischemia. We also found that GB and IP significantly stimulated astrocytes to express and secrete erythropoietin (EPO) into ACM, and the addition of anti-EPO antibody blocked the protective effect of GB or IP-treated astrocytes culture medium on neurons in ischemia. Further study of above protection revealed that ACM from astrocytes treated with GB or IP induced the inactivation of proapoptotic factor Bad by phosphorylation at serine 136 and 112 ((136)p-Bad and (112)p-Bad) in neurons. Together, our results suggest that GB is capable of preconditioning on astrocytes as IP and then protects neurons against ischemia-induced apoptosis, which is mediated by EPO.
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Affiliation(s)
- Xiaomei Wu
- Department of Neurochemistry, Institute for Nautical Medicine, Nantong University, Nantong 226001, PR China
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Tauskela JS, Aylsworth A, Hewitt M, Brunette E, Mealing GAR. Preconditioning induces tolerance by suppressing glutamate release in neuron culture ischemia models. J Neurochem 2012; 122:470-81. [DOI: 10.1111/j.1471-4159.2012.07791.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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19
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Rowley NM, Madsen KK, Schousboe A, Steve White H. Glutamate and GABA synthesis, release, transport and metabolism as targets for seizure control. Neurochem Int 2012; 61:546-58. [PMID: 22365921 DOI: 10.1016/j.neuint.2012.02.013] [Citation(s) in RCA: 110] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Accepted: 02/09/2012] [Indexed: 11/17/2022]
Abstract
The synthesis, release, reuptake, and metabolism of the excitatory and inhibitory neurotransmitters glutamate and GABA, respectively, are tightly controlled. Given the role that these two neurotransmitters play in normal and abnormal neurotransmission, it is important to consider the processes whereby they are regulated. This brief review is focused entirely on the metabolic aspects of glutamate and GABA synthesis and neurotransmission. It describes in limited detail the synthesis, release, reuptake, metabolism, cellular compartmentation and pharmacology of the glutamatergic and GABAergic synapse. This review also provides a summary and brief description of the pathologic and phenotypic features of the various genetic animal models that have been developed in an effort to provide a greater understanding of the role that each of the aforementioned metabolic processes plays in controlling excitatory and inhibitory neurotransmission and how their use will hopefully facilitate the development of safer and more efficacious therapies for the treatment of epilepsy and other neurological disorders.
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Affiliation(s)
- Nicole M Rowley
- Department of Pharmacology and Toxicology, Anticonvulsant Drug Development Program, University of Utah, 417 Wakara Way, Suite 3211, Salt Lake City, UT 84108, USA
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Nuclear factor-κB contributes to neuron-dependent induction of glutamate transporter-1 expression in astrocytes. J Neurosci 2011; 31:9159-69. [PMID: 21697367 DOI: 10.1523/jneurosci.0302-11.2011] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The glutamate transporter-1 [GLT-1 (excitatory amino acid transporter 2)] subtype of glutamate transporter ensures crisp excitatory signaling and limits excitotoxicity in the CNS. Astrocytic expression of GLT-1 is regulated during development, by neuronal activity, and in neurodegenerative diseases. Although neurons activate astrocytic expression of GLT-1, the mechanisms involved have not been identified. In the present study, astrocytes from transgenic mice that express enhanced green fluorescent protein (eGFP) under the control of a bacterial artificial chromosome (BAC) containing a very large region of DNA surrounding the GLT-1 gene (BAC GLT-1 eGFP mice) were used to assess the role of nuclear factor-κB (NF-κB) in neuron-dependent activation of the GLT-1 promoter. We provide evidence that neurons activate NF-κB signaling in astrocytes. Transduction of astrocytes from the BAC GLT-1 eGFP mice with dominant-negative inhibitors of NF-κB signaling completely blocked neuron-dependent activation of a NF-κB reporter construct and attenuated induction of eGFP. Exogenous expression of p65 and/or p50 NF-κB subunits induced expression of eGFP or GLT-1 and increased GLT-1-mediated transport activity. Using wild-type and mutant GLT-1 promoter reporter constructs, we found that NF-κB sites at -583 or -251 relative to the transcription start site were required for neuron-dependent reporter activation. Electrophoretic mobility shift and supershift assays reveal that p65 and p50 interact with these same sites ex vivo. Finally, chromatin immunoprecipitation showed that p65 and p50 interact with these sites in adult cortex, but not in kidney (a tissue that expresses no detectable GLT-1). Together, these studies strongly suggest that NF-κB contributes to neuron-dependent regulation of astrocytic GLT-1 transcription.
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Pre-conditioning induces the precocious differentiation of neonatal astrocytes to enhance their neuroprotective properties. ASN Neuro 2011; 3:e00062. [PMID: 21722095 PMCID: PMC3153963 DOI: 10.1042/an20100029] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Hypoxic preconditioning reprogrammes the brain's response to subsequent H/I (hypoxia–ischaemia) injury by enhancing neuroprotective mechanisms. Given that astrocytes normally support neuronal survival and function, the purpose of the present study was to test the hypothesis that a hypoxic preconditioning stimulus would activate an adaptive astrocytic response. We analysed several functional parameters 24 h after exposing rat pups to 3 h of systemic hypoxia (8% O2). Hypoxia increased neocortical astrocyte maturation as evidenced by the loss of GFAP (glial fibrillary acidic protein)-positive cells with radial morphologies and the acquisition of multipolar GFAP-positive cells. Interestingly, many of these astrocytes had nuclear S100B. Accompanying their differentiation, there was increased expression of GFAP, GS (glutamine synthetase), EAAT-1 (excitatory amino acid transporter-1; also known as GLAST), MCT-1 (monocarboxylate transporter-1) and ceruloplasmin. A subsequent H/I insult did not result in any further astrocyte activation. Some responses were cell autonomous, as levels of GS and MCT-1 increased subsequent to hypoxia in cultured forebrain astrocytes. In contrast, the expression of GFAP, GLAST and ceruloplasmin remained unaltered. Additional experiments utilized astrocytes exposed to exogenous dbcAMP (dibutyryl-cAMP), which mimicked several aspects of the preconditioning response, to determine whether activated astrocytes could protect neurons from subsequent excitotoxic injury. dbcAMP treatment increased GS and glutamate transporter expression and function, and as hypothesized, protected neurons from glutamate excitotoxicity. Taken altogether, these results indicate that a preconditioning stimulus causes the precocious differentiation of astrocytes and increases the acquisition of multiple astrocytic functions that will contribute to the neuroprotection conferred by a sublethal preconditioning stress.
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Chao XD, Fei F, Fei Z. The role of excitatory amino acid transporters in cerebral ischemia. Neurochem Res 2010; 35:1224-30. [PMID: 20440555 DOI: 10.1007/s11064-010-0178-3] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2010] [Accepted: 04/20/2010] [Indexed: 12/28/2022]
Abstract
Glutamate is an excitatory neurotransmitter that plays a major role in the pathogenesis of ischemia brain injury. The regulation of glutamate neurotransmission is carried out by excitatory amino acid transporters (EAATs) that act through reuptake of glutamate into cells. EAATs may also release glutamate into the extracellular space in a calcium-independent manner during ischemia and dysfunction of EAATs is specifically implicated in the pathology of cerebral ischemia. Recent studies show that up-regulation of EAAT2 provides neuroprotection during ischemic insult. This review summarizes current knowledge regarding the role of EAATs in cerebral ischemia.
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Affiliation(s)
- Xiao-dong Chao
- Department of Neurosurgery, Xi Jing Hospital, Fourth Military Medical University, Xi'an, China.
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23
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Fattorini G, Melone M, Bragina L, Candiracci C, Cozzi A, Pellegrini Giampietro DE, Torres-Ramos M, Pérez-Samartín A, Matute C, Conti F. GLT-1 expression and Glu uptake in rat cerebral cortex are increased by phencyclidine. Glia 2008; 56:1320-7. [PMID: 18615569 DOI: 10.1002/glia.20700] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Using western blottings, microdialysis, and functional assays we tested the hypothesis that phencyclidine (PCP) modifies the expression and function of glutamate (Glu) transporters in the rat frontal cortex. Western blotting studies revealed that administration of PCP (10 mg/kg/day; 7 days) increased significantly the expression of the astrocytic Glu transporter GLT-1/EAAT2. Functional studies showed that PCP increased significantly Na+-dependent Glu uptake in slices and in neuron/astrocyte co-cultures, and microdialysis studies evidenced that PCP treatment reduced basal Glu output. In our experimental conditions, PCP did not induce toxicity. These studies show that PCP increases the expression of GLT-1 in the cerebral cortex, thereby increasing Glu uptake and reducing extracellular [Glu].
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Affiliation(s)
- Giorgia Fattorini
- Dipartimento di Neuroscienze, Università Politecnica delle Marche, Ancona, Italy
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Cerebral ischemic preconditioning induces lasting effects on CA1 neuronal survival, prevents memory impairments but not ischemia-induced hyperactivity. Behav Brain Res 2008; 189:145-51. [DOI: 10.1016/j.bbr.2007.12.027] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2007] [Revised: 12/20/2007] [Accepted: 12/26/2007] [Indexed: 01/19/2023]
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25
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Obrenovitch TP. Molecular physiology of preconditioning-induced brain tolerance to ischemia. Physiol Rev 2008; 88:211-47. [PMID: 18195087 DOI: 10.1152/physrev.00039.2006] [Citation(s) in RCA: 170] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Ischemic tolerance describes the adaptive biological response of cells and organs that is initiated by preconditioning (i.e., exposure to stressor of mild severity) and the associated period during which their resistance to ischemia is markedly increased. This topic is attracting much attention because preconditioning-induced ischemic tolerance is an effective experimental probe to understand how the brain protects itself. This review is focused on the molecular and related functional changes that are associated with, and may contribute to, brain ischemic tolerance. When the tolerant brain is subjected to ischemia, the resulting insult severity (i.e., residual blood flow, disruption of cellular transmembrane gradients) appears to be the same as in the naive brain, but the ensuing lesion is substantially reduced. This suggests that the adaptive changes in the tolerant brain may be primarily directed against postischemic and delayed processes that contribute to ischemic damage, but adaptive changes that are beneficial during the subsequent test insult cannot be ruled out. It has become clear that multiple effectors contribute to ischemic tolerance, including: 1) activation of fundamental cellular defense mechanisms such as antioxidant systems, heat shock proteins, and cell death/survival determinants; 2) responses at tissue level, especially reduced inflammatory responsiveness; and 3) a shift of the neuronal excitatory/inhibitory balance toward inhibition. Accordingly, an improved knowledge of preconditioning/ischemic tolerance should help us to identify neuroprotective strategies that are similar in nature to combination therapy, hence potentially capable of suppressing the multiple, parallel pathophysiological events that cause ischemic brain damage.
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Affiliation(s)
- Tihomir Paul Obrenovitch
- Division of Pharmacology, School of Life Sciences, University of Bradford, Bradford, United Kingdom.
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Sheldon AL, Robinson MB. The role of glutamate transporters in neurodegenerative diseases and potential opportunities for intervention. Neurochem Int 2007; 51:333-55. [PMID: 17517448 PMCID: PMC2075474 DOI: 10.1016/j.neuint.2007.03.012] [Citation(s) in RCA: 432] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2007] [Revised: 03/28/2007] [Accepted: 03/30/2007] [Indexed: 12/20/2022]
Abstract
Extracellular concentrations of the predominant excitatory neurotransmitter, glutamate, and related excitatory amino acids are maintained at relatively low levels to ensure an appropriate signal-to-noise ratio and to prevent excessive activation of glutamate receptors that can result in cell death. The latter phenomenon is known as 'excitotoxicity' and has been associated with a wide range of acute and chronic neurodegenerative disorders, as well as disorders that result in the loss of non-neural cells such as oligodendroglia in multiple sclerosis. Unfortunately clinical trials with glutamate receptor antagonists that would logically seem to prevent the effects of excessive receptor activation have been associated with untoward side effects or little clinical benefit. In the mammalian CNS, the extracellular concentrations of glutamate are controlled by two types of transporters; these include a family of Na(+)-dependent transporters and a cystine-glutamate exchange process, referred to as system X(c)(-). In this review, we will focus primarily on the Na(+)-dependent transporters. A brief introduction to glutamate as a neurotransmitter will be followed by an overview of the properties of these transporters, including a summary of the presumed physiologic mechanisms that regulate these transporters. Many studies have provided compelling evidence that impairing the function of these transporters can increase the sensitivity of tissue to deleterious effects of aberrant activation of glutamate receptors. Over the last decade, it has become clear that many neurodegenerative disorders are associated with a change in localization and/or expression of some of the subtypes of these transporters. This would suggest that therapies directed toward enhancing transporter expression might be beneficial. However, there is also evidence that glutamate transporters might increase the susceptibility of tissue to the consequences of insults that result in a collapse of the electrochemical gradients required for normal function such as stroke. In spite of the potential adverse effects of upregulation of glutamate transporters, there is recent evidence that upregulation of one of the glutamate transporters, GLT-1 (also called EAAT2), with beta-lactam antibiotics attenuates the damage observed in models of both acute and chronic neurodegenerative disorders. While it seems somewhat unlikely that antibiotics specifically target GLT-1 expression, these studies identify a potential strategy to limit excitotoxicity. If successful, this type of approach could have widespread utility given the large number of neurodegenerative diseases associated with decreases in transporter expression and excitotoxicity. However, given the massive effort directed at developing glutamate receptor agents during the 1990s and the relatively modest advances to date, one wonders if we will maintain the patience needed to carefully understand the glutamatergic system so that it will be successfully targeted in the future.
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Affiliation(s)
- Amanda L. Sheldon
- Department of Neuroscience, University of Pennsylvania, Philadelphia, PA. 19104-4318
- Departments of Pediatrics and Pharmacology, Children’s Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA. 19104-4318
| | - Michael B. Robinson
- Departments of Pediatrics and Pharmacology, Children’s Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA. 19104-4318
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Zhao HG, Sun XC, Xian XH, Li WB, Zhang M, Li QJ. The Role of Nitric Oxide in the Neuroprotection of Limb Ischemic Preconditioning in Rats. Neurochem Res 2007; 32:1919-26. [PMID: 17551830 DOI: 10.1007/s11064-007-9381-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2007] [Accepted: 05/08/2007] [Indexed: 10/23/2022]
Abstract
Brief limb ischemia was reported to protect neurons against injury induced by subsequent cerebral ischemia-reperfusion, and this phenomenon is known as limb ischemic preconditioning (LIP). To explore the role of nitric oxide (NO) in neuroprotection of LIP in rats, we observed changes in the content of nitric oxide (NO) and activity of NO synthase (NOS) in the serum and CA1 hippocampus of rats after transient limb ischemic preconditioning (LIP), and the influence of N(G)-nitro-L-arginine methylester (L-NAME), a NOS inhibitor, on the neuroprotection of LIP against cerebral ischemia-reperfusion injury. Results showed that NO content and NOS activity in serum increased significantly after LIP compared with the sham group. The increase showed a double peak pattern, in which the first one appeared at time 0 (immediate time point) and the second one appeared at 48 h after the LIP (P < 0.01). The NO content and NOS activity in the CA1 hippocampus in LIP group showed similar change pattern with the changes in the serum, except for the first peak of up-regulation of NO content and NOS activity appeared at 6 h after LIP. Pretreatment with L-NAME before LIP blocked the neuroprotection of LIP against subsequent cerebral ischemic insult. The blocking effect of L-NAME was abolished with pretreatment of L-Arg. These findings indicated that NO may be associated with the tolerance of pyramidal cells in the CA1 hippocampus to ischemia induced by LIP in rats.
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Affiliation(s)
- Hong-Gang Zhao
- Department of Pathophysiology, Institute of Basic Medicine, Hebei Medical University, 361 Zhongshan East Road, 050017 Shijiazhuang, P R China
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Tanaka M, Kawahara K, Kosugi T, Yamada T, Mioka T. Changes in the spontaneous calcium oscillations for the development of the preconditioning-induced ischemic tolerance in neuron/astrocyte co-culture. Neurochem Res 2007; 32:988-1001. [PMID: 17401678 DOI: 10.1007/s11064-006-9259-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2006] [Accepted: 12/19/2006] [Indexed: 10/23/2022]
Abstract
Spontaneous Ca(2+) oscillations are believed to contribute to the regulation of gene expression. Here we investigated whether and how the dynamics of Ca(2+) oscillations changed after sublethal preconditioning (PC) for PC-induced ischemic tolerance in neuron/astrocyte co-cultures. The frequency of spontaneous Ca(2+) oscillations significantly decreased between 4 and 8 h after the end of PC in both neurons and astrocytes. Treatment with 2-APB, an inhibitor of IP3 receptors, decreased the oscillatory frequency, induced ischemic tolerance and a down-regulation of glutamate transporter GLT-1 contributing to the increase in the extracellular glutamate during ischemia. The expression of GLT-1 is known to be up-regulated by PACAP. Treatment with PACAP38 increased the oscillatory frequency, and antagonized both the PC-induced down-regulation of GLT-1 and ischemic tolerance. These results suggested that the PC suppressed the spontaneous Ca(2+) oscillations regulating the gene expressions of various proteins, especially of astrocytic GLT-1, for the development of the PC-induced ischemic tolerance.
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Affiliation(s)
- Motoki Tanaka
- Laboratory of Cellular Cybernetics, Graduate School of Information Science and Technology, Hokkaido University, Sapporo, Japan
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Steiger HJ, Hänggi D. Ischaemic preconditioning of the brain, mechanisms and applications. Acta Neurochir (Wien) 2007; 149:1-10. [PMID: 17151832 DOI: 10.1007/s00701-006-1057-1] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2006] [Accepted: 10/11/2006] [Indexed: 01/25/2023]
Abstract
BACKGROUND The concept of ischaemic preconditioning was introduced in the late 1980s. The concept emerged that a brief subcritical ischaemic challenge could mobilize intrinsic protective mechanisms that increased tolerance against subsequent critical ischaemia. Tissues with a high sensitivity against ischaemia, i.e. myocardium and central nervous system, present the most promising targets for therapeutic application of ischaemic preconditioning. During the last years the mechanisms of neuronal preconditioning were systematically studied and a number of molecular regulation pathways were discovered to participate in preconditioning. The purpose of the present review is to survey the actual knowledge on cerebral preconditioning, and to define the practical impact for neurosurgery. METHODS A systematic medline search for the terms preconditioning and postconditioning was filed. Publications related to the nervous system were selected and analysed. FINDINGS Preconditioning can be subdivided into early and late mechanisms, depending on whether the effect appears immediately after the nonlethal stress or with a delay of some hours or days. In general early effects can be linked to adaptation of membrane receptors whereas late effects are the result of gene up- or downregulation. Not only subcritical ischaemia can trigger preconditioning but also hypoxia, hyperthermia, isoflurane and other chemical substances. Although a vast amount of knowledge has been accumulated regarding neural preconditioning, it is unknown whether the effects can be potentiated by pharmacological or hypothermic neuroprotection during the critical ischaemia. Furthermore, although the practical importance of these findings is obvious, the resulting protective manipulations have so far not been transferred into clinical neurosurgery. Postconditioning and remote ischaemic preconditioning are additional emerging concepts. Postconditioning with a series of mechanical interruptions of reperfusion can apparently reduce ischaemic damage. Remote ischaemic preconditioning refers to the concept that transient ischaemia for example of a limb can lead to protection of the myocardium and possibly the brain. CONCLUSION Possible cumulative neuroprotection by preconditioning and pharmacological protection during critical ischaemia should be studied systematically. Easy to apply methods of preconditioning, such as the application of volatile anaesthetics or erythropoietin some hours or days prior to planned temporary ischaemia, should be introduced into the practice of operative neurosurgery.
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Affiliation(s)
- H-J Steiger
- Department of Neurosurgery, University Hospital, Heinrich-Heine University, Düsseldorf, Germany.
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