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Neves D, Salazar IL, Almeida RD, Silva RM. Molecular mechanisms of ischemia and glutamate excitotoxicity. Life Sci 2023; 328:121814. [PMID: 37236602 DOI: 10.1016/j.lfs.2023.121814] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Revised: 05/05/2023] [Accepted: 05/23/2023] [Indexed: 05/28/2023]
Abstract
Excitotoxicity is classically defined as the neuronal damage caused by the excessive release of glutamate, and subsequent activation of excitatory plasma membrane receptors. In the mammalian brain, this phenomenon is mainly driven by excessive activation of glutamate receptors (GRs). Excitotoxicity is common to several chronic disorders of the Central Nervous System (CNS) and is considered the primary mechanism of neuronal loss of function and cell death in acute CNS diseases (e.g. ischemic stroke). Multiple mechanisms and pathways lead to excitotoxic cell damage including pro-death signaling cascade events downstream of glutamate receptors, calcium (Ca2+) overload, oxidative stress, mitochondrial impairment, excessive glutamate in the synaptic cleft as well as altered energy metabolism. Here, we review the current knowledge on the molecular mechanisms that underlie excitotoxicity, emphasizing the role of Nicotinamide Adenine Dinucleotide (NAD) metabolism. We also discuss novel and promising therapeutic strategies to treat excitotoxicity, highlighting recent clinical trials. Finally, we will shed light on the ongoing search for stroke biomarkers, an exciting and promising field of research, which may improve stroke diagnosis, prognosis and allow better treatment options.
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Affiliation(s)
- Diogo Neves
- iBiMED - Institute of Biomedicine, Department of Medical Sciences, University of Aveiro, Aveiro, Portugal
| | - Ivan L Salazar
- Multidisciplinary Institute of Ageing, MIA - Portugal, University of Coimbra, Coimbra, Portugal
| | - Ramiro D Almeida
- iBiMED - Institute of Biomedicine, Department of Medical Sciences, University of Aveiro, Aveiro, Portugal; CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.
| | - Raquel M Silva
- iBiMED - Institute of Biomedicine, Department of Medical Sciences, University of Aveiro, Aveiro, Portugal; Universidade Católica Portuguesa, Faculdade de Medicina Dentária, Centro de Investigação Interdisciplinar em Saúde, Viseu, Portugal.
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2
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Li SH, Abd-Elrahman KS, Ferguson SS. Targeting mGluR2/3 for treatment of neurodegenerative and neuropsychiatric diseases. Pharmacol Ther 2022; 239:108275. [DOI: 10.1016/j.pharmthera.2022.108275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 08/23/2022] [Accepted: 08/23/2022] [Indexed: 10/15/2022]
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Hernández-Melchor D, Ramírez-Martínez L, Cid L, Palafox-Gómez C, López-Bayghen E, Ortega A. EAAT1-dependent slc1a3 Transcriptional Control depends on the Substrate Translocation Process. ASN Neuro 2022; 14:17590914221116574. [PMID: 35903937 PMCID: PMC9340397 DOI: 10.1177/17590914221116574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Glutamate, the major excitatory neurotransmitter in the vertebrate brain, is removed from the synaptic cleft by a family of sodium-dependent transporters expressed in neurons and glial cells. The bulk of glutamate uptake activity occurs in glial cells through the sodium-dependent glutamate/aspartate transporter (EAAT1/GLAST) and glutamate transporter 1 (EAAT2/GLT-1). EAAT1/GLAST is the predominant transporter within the cerebellum. It is highly enriched in Bergmann glial cells that span the cerebellar cortex and wrap the most abundant glutamatergic synapses in the central nervous system, the synapse formed by the parallel fibers and the Purkinje cells. In the past years, it has become evident that Bergmann glial cells are involved in glutamatergic transmission. Glutamate transporters are tightly regulated due to their essential role in tripartite synapses. Glutamate regulates EAAT1/GLAST function and gene expression in a receptor-dependent and receptor-independent manner. Through the use of the non-metabolizable EAAT1/GLAST ligand, D-Aspartate, and the well-established chick cerebellar Bergmann glia primary culture, in this contribution, we demonstrate that EAAT1/GLAST down-regulates its expression and function at the transcriptional level through the activation of a signaling pathway that includes the phosphatidyl inositol 3 kinase (PI3K), the Ca2+/diacylglycerol dependent protein kinase PKC and the nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB). These results favor the notion of an activity-dependent fine-tuning of glutamate recycling and its synaptic transactions through glial cells. Summary statement EAAT1/GLAST down-regulates its expression and function at the transcriptional level by activating a signaling pathway that includes PI3K, PKC and NF-κB, favoring the notion of an activity-dependent fine-tuning of glutamate recycling and its synaptic transactions through glial cells.
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Affiliation(s)
- Dinorah Hernández-Melchor
- Departamento de Toxicología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México City, México
- Science, Technology and Society Program. Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México City, México
| | - Leticia Ramírez-Martínez
- Departamento de Toxicología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México City, México
| | - Luis Cid
- Departamento de Toxicología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México City, México
| | - Cecilia Palafox-Gómez
- Departamento de Toxicología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México City, México
| | - Esther López-Bayghen
- Departamento de Toxicología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México City, México
| | - Arturo Ortega
- Departamento de Toxicología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México City, México
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Li SH, Colson TLL, Abd-Elrahman KS, Ferguson SS. mGluR2/3 Activation Improves Motor Performance and Reduces Pathology in heterozygous zQ175 Huntington's Disease Mice. J Pharmacol Exp Ther 2021; 379:74-84. [PMID: 34330748 DOI: 10.1124/jpet.121.000735] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 07/20/2021] [Indexed: 11/22/2022] Open
Abstract
Huntington's Disease (HD) is an autosomal dominant neurodegenerative disease that leads to progressive motor impairment with no available disease-modifying treatments. Current evidence indicates that exacerbated postsynaptic glutamate signaling in the striatum plays a key role in the pathophysiology of HD. However, it remains unclear whether reducing glutamate release can be an effective approach to slow the progression of HD. Here, we show that the activation of metabotropic glutamate receptors 2 and 3 (mGluR2/3), which inhibit presynaptic glutamate release, improves HD symptoms and pathology in heterozygous zQ175 knock-in mice. Treatment of both male and female zQ175 mice with the potent and selective mGluR2/3 agonist LY379268 for either 4 or 8 weeks improves both limb coordination and locomotor function in all mice. LY379268 also reduces mutant huntingtin aggregate formation, neuronal cell death, and microglia activation in the striatum of both male and female zQ175 mice. The reduction in mutant huntingtin protein correlates with the activation of a GSK3β-dependent autophagy pathway in male, but not female, zQ175 mice. Furthermore, LY379268 reduces both Akt and ERK1/2 phosphorylation in male zQ175 mice but increases both Akt and ERK1/2 phosphorylation in female zQ175 mice. Taken together, our results indicate that mGluR2/3 activation mitigates HD neuropathology in both male and female mice but is associated with the differential activation and inactivation of cell signaling pathways in heterozygous male and female zQ175 mice. This further highlights the need to take sex into consideration when developing future HD therapeutics. Significance Statement The mGluR2/3 agonist LY379268 improves motor impairments and reduces pathology in male and female zQ175 Huntington's mice. The beneficial outcomes of LY379268 treatment in Huntington's mice were mediated by divergent cell signalling pathways in both sexes. We provide evidence that mGluR2/3 agonists can be repurposed for the treatment of Huntington's disease and we emphasize the importance of investigating sex as a biological variable in preclinical disease modifying studies.
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Rodríguez-Campuzano AG, Ortega A. Glutamate transporters: Critical components of glutamatergic transmission. Neuropharmacology 2021; 192:108602. [PMID: 33991564 DOI: 10.1016/j.neuropharm.2021.108602] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 04/09/2021] [Accepted: 04/27/2021] [Indexed: 02/06/2023]
Abstract
Glutamate is the major excitatory neurotransmitter in the vertebrate central nervous system. Once released, it binds to specific membrane receptors and transporters activating a wide variety of signal transduction cascades, as well as its removal from the synaptic cleft in order to avoid its extracellular accumulation and the overstimulation of extra-synaptic receptors that might result in neuronal death through a process known as excitotoxicity. Although neurodegenerative diseases are heterogenous in clinical phenotypes and genetic etiologies, a fundamental mechanism involved in neuronal degeneration is excitotoxicity. Glutamate homeostasis is critical for brain physiology and Glutamate transporters are key players in maintaining low extracellular Glutamate levels. Therefore, the characterization of Glutamate transporters has been an active area of glutamatergic research for the last 40 years. Transporter activity its regulated at different levels: transcriptional and translational control, transporter protein trafficking and membrane mobility, and through extensive post-translational modifications. The elucidation of these mechanisms has emerged as an important piece to shape our current understanding of glutamate actions in the nervous system.
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Affiliation(s)
- Ada G Rodríguez-Campuzano
- Departamento de Toxicología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Apartado Postal 14-740, Ciudad de México, 07000, Mexico
| | - Arturo Ortega
- Departamento de Toxicología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Apartado Postal 14-740, Ciudad de México, 07000, Mexico.
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Burgos-Aguilar C, Ferris MJ, Sexton LL, Sun H, Xiao R, Chen R, Childers SR, Howlett AC. Metabotropic glutamate 2,3 receptor stimulation desensitizes agonist activation of G-protein signaling and alters transcription regulators in mesocorticolimbic brain regions. Synapse 2021; 75:e22190. [PMID: 33025628 PMCID: PMC8552243 DOI: 10.1002/syn.22190] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 08/26/2020] [Accepted: 09/06/2020] [Indexed: 01/07/2023]
Abstract
Metabotropic glutamate (mGlu) receptors are regulators of glutamate release and targets for development of therapies for hyperactive glutamatergic signaling. However, the effects of long-term stimulation of mGlu receptors on cellular signaling in the brain have not been described. This study investigated the effects of 2-day and 14-day osmotic mini-pump administration of the mGlu2,3 agonist LY379268 (3.0 mg kg-1 day-1 ) to rats on receptor-mediated G-protein activation and signaling in mesocorticolimbic regions in rat brain sections. A significant reduction in LY379268-stimulated [35 S]GTPγS binding was observed in the 14-day group in some cortical regions, prefrontal cortex, nucleus accumbens, and ventral pallidum. The 14-day LY379268 treatment group exhibited mGlu2 mRNA levels significantly lower in hippocampus, nucleus accumbens, caudate, and ventral pallidum. In both 2-day and 14-day treatment groups immunodetectable phosphorylated cAMP Response Element-Binding protein (CREB) was significantly reduced across all brain regions. In the 2-day group, we observed significantly lower immunodetectable CREB protein across all brain regions, which was subsequently increased in the 14-day group but failed to achieve control values. Neither immunodetectable extracellular signal-regulated kinase (ERK) protein nor phosphorylated ERK from 2-day or 14-day treatment groups differed significantly from control across all brain regions. However, the ratio of phosphorylated ERK to total ERK protein was significantly greater in the 14-day treatment group compared with the control. These results identify compensatory changes to mGlu2,3 signal transduction in rat brains after chronic systemic administration of agonist, which could be predictive of the mechanism of action in human pharmacotherapies.
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Affiliation(s)
- Carolina Burgos-Aguilar
- Department of Physiology and Pharmacology and Center for the Neurobiology of Addiction Treatment, One Medical Center Blvd., Wake Forest School of Medicine, Winston-Salem, NC 27157 USA
| | - Mark J. Ferris
- Department of Physiology and Pharmacology and Center for the Neurobiology of Addiction Treatment, One Medical Center Blvd., Wake Forest School of Medicine, Winston-Salem, NC 27157 USA
| | - Lacey L. Sexton
- Department of Physiology and Pharmacology and Center for the Neurobiology of Addiction Treatment, One Medical Center Blvd., Wake Forest School of Medicine, Winston-Salem, NC 27157 USA
| | - Haiguo Sun
- Department of Physiology and Pharmacology and Center for the Neurobiology of Addiction Treatment, One Medical Center Blvd., Wake Forest School of Medicine, Winston-Salem, NC 27157 USA
| | - Ruoyu Xiao
- Department of Physiology and Pharmacology and Center for the Neurobiology of Addiction Treatment, One Medical Center Blvd., Wake Forest School of Medicine, Winston-Salem, NC 27157 USA
| | - Rong Chen
- Department of Physiology and Pharmacology and Center for the Neurobiology of Addiction Treatment, One Medical Center Blvd., Wake Forest School of Medicine, Winston-Salem, NC 27157 USA
| | - Steven R. Childers
- Department of Physiology and Pharmacology and Center for the Neurobiology of Addiction Treatment, One Medical Center Blvd., Wake Forest School of Medicine, Winston-Salem, NC 27157 USA
| | - Allyn C. Howlett
- Department of Physiology and Pharmacology and Center for the Neurobiology of Addiction Treatment, One Medical Center Blvd., Wake Forest School of Medicine, Winston-Salem, NC 27157 USA
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Revuelta M, Elicegui A, Scheuer T, Endesfelder S, Bührer C, Moreno-Cugnon L, Matheu A, Schmitz T. In vitro P38MAPK inhibition in aged astrocytes decreases reactive astrocytes, inflammation and increases nutritive capacity after oxygen-glucose deprivation. Aging (Albany NY) 2021; 13:6346-6358. [PMID: 33563843 PMCID: PMC7993689 DOI: 10.18632/aging.202651] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 12/18/2020] [Indexed: 01/02/2023]
Abstract
Proper astroglial functioning is essential for the development and survival of neurons and oligodendroglia under physiologic and pathological circumstances. Indeed, malfunctioning of astrocytes represents an important factor contributing to brain injury. However, the molecular pathways of this astroglial dysfunction are poorly defined. In this work we show that aging itself can drastically perturb astrocyte viability with an increase of inflammation, cell death and astrogliosis. Moreover, we demonstrate that oxygen glucose deprivation (OGD) has a higher impact on nutritive loss in aged astrocytes compared to young ones, whereas aged astrocytes have a higher activity of the anti-oxidant systems. P38MAPK signaling has been identified to be upregulated in neurons, astrocytes and microglia after ischemic stroke. By using a pharmacological p38α specific inhibitor (PH-797804), we show that p38MAPK pathway has an important role in aged astrocytes for inflammatory and oxidative stress responses with the subsequent cell death that occurs after OGD.
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Affiliation(s)
- Miren Revuelta
- Department for Neonatology, Charité University Medical Center, Berlin 13353, Germany
- Cellular Oncology Group, Biodonostia Health Research Institute, Paseo Doctor Begiristain, San Sebastian 20014, Spain
| | - Amaia Elicegui
- Department for Neonatology, Charité University Medical Center, Berlin 13353, Germany
- Neurovascular Research Laboratory, Vall d’Hebron Institute of Research, Barcelona 08035, Spain
| | - Till Scheuer
- Department for Neonatology, Charité University Medical Center, Berlin 13353, Germany
| | - Stefanie Endesfelder
- Department for Neonatology, Charité University Medical Center, Berlin 13353, Germany
| | - Christoph Bührer
- Department for Neonatology, Charité University Medical Center, Berlin 13353, Germany
| | - Leire Moreno-Cugnon
- Cellular Oncology Group, Biodonostia Health Research Institute, Paseo Doctor Begiristain, San Sebastian 20014, Spain
| | - Ander Matheu
- Cellular Oncology Group, Biodonostia Health Research Institute, Paseo Doctor Begiristain, San Sebastian 20014, Spain
- IKERBASQUE, Basque Foundation for Science, Bilbao 48013, Spain
- CIBERfes, Madrid 28029, Spain
| | - Thomas Schmitz
- Department for Neonatology, Charité University Medical Center, Berlin 13353, Germany
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Lin CH, Chen HY, Wei KC. Role of HMGB1/TLR4 Axis in Ischemia/Reperfusion-Impaired Extracellular Glutamate Clearance in Primary Astrocytes. Cells 2020; 9:E2585. [PMID: 33287126 PMCID: PMC7761728 DOI: 10.3390/cells9122585] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 11/20/2020] [Accepted: 12/01/2020] [Indexed: 11/17/2022] Open
Abstract
(1) Background: Abnormal accumulation of extracellular glutamate can occur as dysfunction of astrocytic glutamate transporters, which has been linked to ischemic brain injury. Excessive extracellular glutamate-induced abnormal excitotoxicity is the major cause of secondary neuronal damage after cerebral ischemia/reperfusion. However, the definite mechanism of impaired astrocytic glutamate reuptake remains unclear. (2) Methods: We investigated the mechanism of the HMGB1/TLR4 axis in extracellular glutamate clearance in primary astrocytes exposed to ischemia/reperfusion by using OGD/R (oxygen-glucose deprivation/reoxygenation) model. (3) Results: OGD/R insult activated the HMGB1/TLR4 axis for reducing the activity of glutamate clearance by inhibiting GLAST (glutamate aspartate transporter) expression in primary astrocytes. Interestingly, OGD/R-untreated astrocytes showed impairment of glutamate clearance after exposure to exogenous HMGB1 or conditioned medium from OGD/R-treated astrocytes culture. Inhibition of HMGB1 or TLR4 effectively prevented impaired glutamate clearance, which was induced by OGD/R, exogenous HMGB1, or conditioned medium from OGD/R-treated astrocytes. Furthermore, glycyrrhizic acid attenuated OGD/R-induced impairment of astrocytic glutamate clearance mediated by the HMGB1-TLR4 axis. (4) Conclusion: The HMGB1/TLR4 axis is a potential target for the treatment of post-ischemic excitotoxicity caused by GLAST dysfunction in astrocytes.
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Affiliation(s)
- Chia-Ho Lin
- Master and PhD Programs in Pharmacology and Toxicology, School of Medicine, Tzu Chi University, Hualien 970, Taiwan; (C.-H.L.); (H.-Y.C.)
- Department of Pharmacology, School of Medicine, Tzu Chi University, Hualien 970, Taiwan
| | - Han-Yu Chen
- Master and PhD Programs in Pharmacology and Toxicology, School of Medicine, Tzu Chi University, Hualien 970, Taiwan; (C.-H.L.); (H.-Y.C.)
| | - Kai-Che Wei
- Department of Dermatology, Kaohsiung Veterans General Hospital, Kaohsiung 802, Taiwan
- School of Medicine, National Yang-Ming University, Taipei 112, Taiwan
- Faculty of Yuh-Ing Junior College of Health Care and Management, Kaohsiung 802, Taiwan
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Cui X, Zhang F, Zhang H, Huang X, Wang K, Huang T, Yang X, Zou L. Neuroprotective Effect of Optogenetics Varies With Distance From Channelrhodopsin-2 Expression in an Amyloid-β-Injected Mouse Model of Alzheimer's Disease. Front Neurosci 2020; 14:583628. [PMID: 33162881 PMCID: PMC7584457 DOI: 10.3389/fnins.2020.583628] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 09/14/2020] [Indexed: 11/13/2022] Open
Abstract
Background: Alzheimer’s disease (AD) is a progressive neurodegenerative disease that is the most common cause of dementia. Optogenetics uses a combination of genetic engineering and light to activate or inhibit specific neurons in the brain. Objective: The objective of the study was to examine the effect of activation of glutamatergic neurons in the hippocampus of mice injected with Aβ1-42 on memory function and biomarkers of neuroinflammation and neuroprotection in the brain to elucidate the clinical utility of optogenetic neuromodulation in AD. Methods: AAV5–CaMKII–channelrhodopsin-2 (CHR2)–mCherry (Aβ-CHR2 mice) or AAV5—CaMKII–mCherry (Aβ-non-CHR2 mice) was injected into the dentate gyrus (DG) of the bilateral hippocampus of an Aβ1-42-injected mouse model of AD. The novel object recognition test was used to investigate working memory (M1), short-term memory (M2), and long-term memory (M3) after Aβ1-42 injection. Hippocampus tissues were collected for immunohistochemical analysis. Results: Compared to controls, M1 and M2 were significantly higher in Aβ-CHR2 mice, but there was no significant difference in M3; NeuN and synapsin expression were significantly increased in the DG of Aβ-CHR2 mice, but not in CA1, CA3, the subventricular zone (SVZ), or the entorhinal cortex (ENT); GluR2 and IL-10 expressions were significantly increased, and GFAP expression was significantly decreased, in CA1, CA3, the DG, and the SVZ of Aβ-CHR2 mice, but not in the ENT. Conclusion: Activation of glutamatergic neurons by optogenetics in the bilateral DG of an Aβ-injected mouse model of AD improved M1 and M2, but not M3. A single-target optogenetics strategy has spatial limitations; therefore, a multiple targeted optogenetics approach to AD therapy should be explored.
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Affiliation(s)
- Xiaorui Cui
- Department of Neurology, Second Clinical Medical College of Jinan University, Shenzhen People's Hospital, Shenzhen, China.,Department of Neurology, Affiliated Hospital of Xiangnan University, Chenzhou, China
| | - Feng Zhang
- Intensive Care Unit, The First Affiliated Hospital, Jinan University, Guangzhou, China
| | - Hui Zhang
- Department of Neurology, Shenzhen People's Hospital (First Affiliated Hospital of Southern University of Science and Technology), Second Clinical College, Jinan University, Shenzhen, China
| | - Xi Huang
- Department of Neurology, Shenzhen People's Hospital (First Affiliated Hospital of Southern University of Science and Technology), Second Clinical College, Jinan University, Shenzhen, China
| | - Kewei Wang
- Department of Neurology, Longgang District People's Hospital of Shenzhen, Shenzhen, China
| | - Ting Huang
- Department of Cerebrovascular Disease, People's Hospital of Yuxi, The Sixth Affiliated Hospital of Kunming Medical University, Yuxi, China
| | - Xifei Yang
- Key Laboratory of Modern Toxicology of Shenzhen, Shenzhen Center for Disease Control and Prevention, Shenzhen, China
| | - Liangyu Zou
- Department of Neurology, Shenzhen People's Hospital (First Affiliated Hospital of Southern University of Science and Technology), Second Clinical College, Jinan University, Shenzhen, China
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Malik AR, Willnow TE. Excitatory Amino Acid Transporters in Physiology and Disorders of the Central Nervous System. Int J Mol Sci 2019; 20:ijms20225671. [PMID: 31726793 PMCID: PMC6888459 DOI: 10.3390/ijms20225671] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 11/07/2019] [Accepted: 11/11/2019] [Indexed: 12/12/2022] Open
Abstract
Excitatory amino acid transporters (EAATs) encompass a class of five transporters with distinct expression in neurons and glia of the central nervous system (CNS). EAATs are mainly recognized for their role in uptake of the amino acid glutamate, the major excitatory neurotransmitter. EAATs-mediated clearance of glutamate released by neurons is vital to maintain proper glutamatergic signalling and to prevent toxic accumulation of this amino acid in the extracellular space. In addition, some EAATs also act as chloride channels or mediate the uptake of cysteine, required to produce the reactive oxygen speciesscavenger glutathione. Given their central role in glutamate homeostasis in the brain, as well as their additional activities, it comes as no surprise that EAAT dysfunctions have been implicated in numerous acute or chronic diseases of the CNS, including ischemic stroke and epilepsy, cerebellar ataxias, amyotrophic lateral sclerosis, Alzheimer’s disease and Huntington’s disease. Here we review the studies in cellular and animal models, as well as in humans that highlight the roles of EAATs in the pathogenesis of these devastating disorders. We also discuss the mechanisms regulating EAATs expression and intracellular trafficking and new exciting possibilities to modulate EAATs and to provide neuroprotection in course of pathologies affecting the CNS.
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Affiliation(s)
- Anna R. Malik
- Nencki Institute of Experimental Biology, 02-093 Warsaw, Poland
- Correspondence:
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11
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Zhang Z, Zhang S, Fu P, Zhang Z, Lin K, Ko JK, Yung KK. Roles of Glutamate Receptors in Parkinson's Disease. Int J Mol Sci 2019; 20:E4391. [PMID: 31500132 DOI: 10.3390/ijms20184391] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 08/26/2019] [Accepted: 08/27/2019] [Indexed: 12/26/2022] Open
Abstract
Parkinson's disease is a progressive neurodegenerative disorder resulting from the degeneration of pigmented dopaminergic neurons in the substantia nigra pars compacta. It induces a series of functional modifications in the circuitry of the basal ganglia nuclei and leads to severe motor disturbances. The amino acid glutamate, as an excitatory neurotransmitter, plays a key role in the disruption of normal basal ganglia function regulated through the interaction with its receptor proteins. It has been proven that glutamate receptors participate in the modulation of neuronal excitability, transmitter release, and long-term synaptic plasticity, in addition to being related to the altered neurotransmission in Parkinson's disease. Therefore, they are considered new targets for improving the therapeutic strategies used to treat Parkinson's disease. In this review, we discuss the biological characteristics of these receptors and demonstrate the receptor-mediated neuroprotection in Parkinson's disease. Pharmacological manipulation of these receptors during anti-Parkinsonian processes in both experimental studies and clinical trials are also summarized.
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12
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Liu Z, Han Y, Zhao H, Luo W, Jia L, Wang Y. Glu-mGluR2/3-ERK Signaling Regulates Apoptosis of Hippocampal Neurons in Diabetic-Depression Model Rats. Evid Based Complement Alternat Med 2019; 2019:3710363. [PMID: 31281399 DOI: 10.1155/2019/3710363] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 04/04/2019] [Accepted: 05/02/2019] [Indexed: 11/29/2022]
Abstract
Objectives Diabetes mellitus is frequently accompanied by depression (diabetes−depression, DD), and DD patients are at higher risk of diabetes-related disability and mortality than diabetes patients without depression. Hippocampal degeneration is a major pathological feature of DD. Here, we investigated the contribution of the Glu−mGluR2/3−ERK signaling pathway to apoptosis of hippocampal neurons in DD model rats. Methods The DD model was established by high-fat diet (HFD) feeding and streptozotocin (STZ) injection followed by chronic unpredictable mild stress (CUMS). Other groups were subjected to HFD + STZ only (diabetes alone) or CUMS only (depression alone). Deficits in hippocampus-dependent memory were assessed in the Morris water maze (MWM), motor activity in the open field test (OFT), and depression-like behavior in the forced swim test (FST). Terminal deoxynucleotidyl transferase (TdT) dUTP nick-end labeling (TUNEL) was used to estimate the rate of hippocampal neuron apoptosis. Hippocampal glutamate (Glu) content was measured by high performance liquid chromatography. Hippocampal expression levels of mGluR2/3, ERK, and the apoptosis effector caspase-3 were estimated by immunohistochemistry and Western blotting. Results DD model rats demonstrated more severe depression-like behavior in the FST, greater spatial learning and memory deficits in the MWM, and reduced horizontal and vertical activity in the OFT compared to control, depression alone, and diabetes alone groups. All of these abnormalities were reversed by treatment with the mGluR2/3 antagonist LY341495. The DD group also exhibited greater numbers of TUNEL-positive hippocampal neurons than all other groups, and this increased apoptosis rate was reversed by LY341495. In addition, hippocampal expression levels of caspase-3 and mGluR2/3 were significantly higher, ERK expression was lower, and Glu was elevated in the DD group. The mGluR2//3 antagonist significantly altered all these features of DD. Conclusions Comorbid diabetes and depression are associated with enhanced hippocampal neuronal apoptosis and concomitantly greater hippocampal dysfunction. These pathogenic effects are regulated by the Glu−mGluR2/3−ERK signaling pathway.
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Hu YJ, Sun Q, Zhang WH, Huo YJ, Xu CJ, Liu JF. Specific activation of mGlu2 induced IGF-1R transactivation in vitro through FAK phosphorylation. Acta Pharmacol Sin 2019; 40:460-7. [PMID: 29946167 DOI: 10.1038/s41401-018-0033-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Accepted: 04/20/2018] [Indexed: 01/17/2023] Open
Abstract
Metabotropic glutamate receptor 2 (mGlu2) belongs to the group-II metabotropic glutamate (mGlu) receptors and is a neurotransmitter G protein-coupled receptor. The group-II mGlu receptors are promising antipsychotic targets, but the specific role of mGlu2 signaling remains unclear. Receptor tyrosine kinases (RTKs) are also believed to participate in brain pathogenesis. To investigate whether there is any communication between mGlu2 and RTKs, we generated a CHO-mGlu2 cell line that stably expresses mGlu2 and showed that activation of mGlu2 by LY379268, a group II mGlu agonist, was able to transactivate insulin-like growth factor 1 receptor (IGF-1R). We further determined that the Gi/o protein, Gβγ subunits, phospholipase C, and focal adhesion kinase (FAK) were involved in the IGF-1R transactivation signaling axis, which further induced the phosphorylation of extracellular signal-regulated kinase1/2 (ERK1/2) and cAMP response element-binding protein. In primary mouse cortical neurons, similar signaling pathways were observed when mGlu2 were stimulated by LY487379, an mGlu2 positive allosteric modulator. Transactivation of IGF-1R through FAK in response to mGlu2 should provide a better understanding of the association of mGlu2 with brain disease.
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Olivares-Bañuelos TN, Chí-Castañeda D, Ortega A. Glutamate transporters: Gene expression regulation and signaling properties. Neuropharmacology 2019; 161:107550. [PMID: 30822498 DOI: 10.1016/j.neuropharm.2019.02.032] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 02/22/2019] [Accepted: 02/24/2019] [Indexed: 12/24/2022]
Abstract
Glutamate is the major excitatory neurotransmitter in the vertebrate central nervous system. During synaptic activity, glutamate is released and binds to specific membrane receptors and transporters activating, in the one hand, a wide variety of signal transduction cascades, while in the other hand, its removal from the synaptic cleft. Extracellular glutamate concentrations are maintained within physiological levels mainly by glia glutamate transporters. Inefficient clearance of this amino acid is neurotoxic due to a prolonged hyperactivation of its postsynaptic receptors, exacerbating a wide array of intracellular events linked to an ionic imbalance, that results in neuronal cell death. This process is known as excitotoxicity and is the underlying mechanisms of an important number of neurodegenerative diseases. Therefore, it is important to understand the regulation of glutamate transporters function. The transporter activity can be regulated at different levels: gene expression, transporter protein targeting and trafficking, and post-translational modifications of the transporter protein. The identification of these mechanisms has paved the way to our current understanding the role of glutamate transporters in brain physiology and will certainly provide the needed biochemical information for the development of therapeutic strategies towards the establishment of novel therapeutic approaches for the treatment and/or prevention of pathologies associated with excitotoxicity insults. This article is part of the issue entitled 'Special Issue on Neurotransmitter Transporters'.
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Affiliation(s)
- Tatiana N Olivares-Bañuelos
- Instituto de Investigaciones Oceanológicas, Universidad Autónoma de Baja California, Carretera Tijuana-Ensenada No. 3917, Fraccionamiento Playitas, 22860, Ensenada, Baja California, Mexico
| | - Donají Chí-Castañeda
- Departamento de Toxicología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Apartado Postal 14-740, Ciudad de México, 07000, Mexico
| | - Arturo Ortega
- Departamento de Toxicología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Apartado Postal 14-740, Ciudad de México, 07000, Mexico.
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Mahmoud S, Gharagozloo M, Simard C, Gris D. Astrocytes Maintain Glutamate Homeostasis in the CNS by Controlling the Balance between Glutamate Uptake and Release. Cells 2019; 8:cells8020184. [PMID: 30791579 PMCID: PMC6406900 DOI: 10.3390/cells8020184] [Citation(s) in RCA: 295] [Impact Index Per Article: 59.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 02/15/2019] [Accepted: 02/19/2019] [Indexed: 01/26/2023] Open
Abstract
Glutamate is one of the most prevalent neurotransmitters released by excitatory neurons in the central nervous system (CNS); however, residual glutamate in the extracellular space is, potentially, neurotoxic. It is now well-established that one of the fundamental functions of astrocytes is to uptake most of the synaptically-released glutamate, which optimizes neuronal functions and prevents glutamate excitotoxicity. In the CNS, glutamate clearance is mediated by glutamate uptake transporters expressed, principally, by astrocytes. Interestingly, recent studies demonstrate that extracellular glutamate stimulates Ca2+ release from the astrocytes’ intracellular stores, which triggers glutamate release from astrocytes to the adjacent neurons, mostly by an exocytotic mechanism. This released glutamate is believed to coordinate neuronal firing and mediate their excitatory or inhibitory activity. Therefore, astrocytes contribute to glutamate homeostasis in the CNS, by maintaining the balance between their opposing functions of glutamate uptake and release. This dual function of astrocytes represents a potential therapeutic target for CNS diseases associated with glutamate excitotoxicity. In this regard, we summarize the molecular mechanisms of glutamate uptake and release, their regulation, and the significance of both processes in the CNS. Also, we review the main features of glutamate metabolism and glutamate excitotoxicity and its implication in CNS diseases.
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Affiliation(s)
- Shaimaa Mahmoud
- Program of Immunology, Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, University of Sherbrooke, Sherbrooke, QC J1H 5N4, Canada.
| | - Marjan Gharagozloo
- Program of Immunology, Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, University of Sherbrooke, Sherbrooke, QC J1H 5N4, Canada.
| | - Camille Simard
- Program of Immunology, Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, University of Sherbrooke, Sherbrooke, QC J1H 5N4, Canada.
| | - Denis Gris
- Program of Immunology, Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, University of Sherbrooke, Sherbrooke, QC J1H 5N4, Canada.
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Le TM, Takarada-Iemata M, Ta HM, Roboon J, Ishii H, Tamatani T, Kitao Y, Hattori T, Hori O. Ndrg2 deficiency ameliorates neurodegeneration in experimental autoimmune encephalomyelitis. J Neurochem 2018; 145:139-153. [PMID: 29315585 DOI: 10.1111/jnc.14294] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 12/10/2017] [Accepted: 12/11/2017] [Indexed: 12/19/2022]
Abstract
N-myc downstream-regulated gene 2 (NDRG2) is a differentiation- and stress-associated molecule that is predominantly expressed in astrocytes in the central nervous system. In this study, we examined the expression and role of NDRG2 in experimental autoimmune encephalomyelitis (EAE), which is an animal model of multiple sclerosis. Western blot and immunohistochemical analysis revealed that the expression of NDRG2 was observed in astrocytes of spinal cord, and was enhanced after EAE induction. A comparative analysis of wild-type and Ndrg2-/- mice revealed that deletion of Ndrg2 ameliorated the clinical symptoms of EAE. Although Ndrg2 deficiency only slightly affected the inflammatory response, based on the results of flow cytometry, qRT-PCR, and immunohistochemistry, it significantly reduced demyelination in the chronic phase, and, more importantly, neurodegeneration both in the acute and chronic phases. Further studies revealed that the expression of astrocytic glutamate transporters, including glutamate aspartate transporter (GLAST) and glutamate transporter 1, was more maintained in the Ndrg2-/- mice compared with wild-type mice after EAE induction. Consistent with these results, studies using cultured astrocytes revealed that Ndrg2 gene silencing increased the expression of GLAST, while NDRG2 over-expression decreased it without altering the expression of glial fibrillary acidic protein. The effect of NDRG2 on GLAST expression was associated with the activation of Akt, but not with the activation of nuclear factor-kappa B. These findings suggest that NDRG2 plays a key role in the pathology of EAE by modulating glutamate metabolism. Cover Image for this Issue: doi: 10.1111/jnc.14173.
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Affiliation(s)
- Thuong Manh Le
- Department of Neuroanatomy, Graduate School of Medical Sciences, Kanazawa University, Kanazawa City, Ishikawa, Japan
| | - Mika Takarada-Iemata
- Department of Neuroanatomy, Graduate School of Medical Sciences, Kanazawa University, Kanazawa City, Ishikawa, Japan
| | - Hieu Minh Ta
- Department of Neuroanatomy, Graduate School of Medical Sciences, Kanazawa University, Kanazawa City, Ishikawa, Japan
| | - Jureepon Roboon
- Department of Neuroanatomy, Graduate School of Medical Sciences, Kanazawa University, Kanazawa City, Ishikawa, Japan
| | - Hiroshi Ishii
- Department of Neuroanatomy, Graduate School of Medical Sciences, Kanazawa University, Kanazawa City, Ishikawa, Japan
| | - Takashi Tamatani
- Department of Neuroanatomy, Graduate School of Medical Sciences, Kanazawa University, Kanazawa City, Ishikawa, Japan
| | - Yasuko Kitao
- Department of Neuroanatomy, Graduate School of Medical Sciences, Kanazawa University, Kanazawa City, Ishikawa, Japan
| | - Tsuyoshi Hattori
- Department of Neuroanatomy, Graduate School of Medical Sciences, Kanazawa University, Kanazawa City, Ishikawa, Japan
| | - Osamu Hori
- Department of Neuroanatomy, Graduate School of Medical Sciences, Kanazawa University, Kanazawa City, Ishikawa, Japan
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Tsai SF, Chen YW, Kuo YM. High-fat diet reduces the hippocampal content level of lactate which is correlated with the expression of glial glutamate transporters. Neurosci Lett 2017; 662:142-146. [PMID: 29051084 DOI: 10.1016/j.neulet.2017.10.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 09/21/2017] [Accepted: 10/16/2017] [Indexed: 12/17/2022]
Abstract
Metabolic disorders hamper the brain metabolism and functions. The astrocytic glucose-derived lactate is known to fill the increased energy needs of neurons during synaptic transmission. However, whether systemic metabolism dysregulation affects the astrocytic lactate metabolism in the brain remain unexamined. To address this question, we adopt a 12-week high-fat diet to induce metabolic disorders in adult mice, and the effects of high-fat diet on the lactate metabolism in the hippocampus were examined. Results showed that a 12-week high-fat diet induced obesity and insulin resistance in mice. High-fat diet also decreased the lactate content levels and the expression of glial glutamate transporters, GLAST and GLT-1, in the hippocampus. Strong correlations between the lactate levels and the levels of GLAST and GLT-1 were evidenced. In conclusion, high-fat feeding induces metabolic disorders and disrupts lactate metabolism in the hippocampus. GLAST and GLT-1 may contribute to the HFD-induced abnormalities of the hippocampal lactate metabolism.
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Affiliation(s)
- Sheng-Feng Tsai
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Yun-Wen Chen
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan; Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Yu-Min Kuo
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan; Department of Cell Biology and Anatomy, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
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18
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Chen KY, Wang LC. Stimulation of IL-1β and IL-6 through NF-κB and sonic hedgehog-dependent pathways in mouse astrocytes by excretory/secretory products of fifth-stage larval Angiostrongylus cantonensis. Parasit Vectors 2017; 10:445. [PMID: 28950910 PMCID: PMC5615811 DOI: 10.1186/s13071-017-2385-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 09/17/2017] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Angiostrongylus cantonensis is an important causative agent of eosinophilic meningitis and eosinophilic meningoencephalitis in humans. Previous studies have shown that the Sonic hedgehog (Shh) signaling pathway may reduce cell apoptosis by inhibiting oxidative stress in A. cantonensis infection. In this study, we investigated the relationship between cytokine secretion and Shh pathway activation after treatment with excretory/secretory products (ESP) of fifth-stage larval A. cantonensis (L5). RESULTS The results showed that IL-1β and IL-6 levels in mouse astrocytes were increased. Moreover, ESP stimulated the protein expression of Shh pathway molecules, including Shh, Ptch, Smo and Gli-1, and induced IL-1β and IL-6 secretion. The transcription factor nuclear factor-κB (NF-κB) plays an important role in inflammation, and it regulates the expression of proinflammatory genes, including cytokines and chemokines, such as IL-1β and TNF-α. After ESP treatment, NF-κB induced IL-1β and IL-6 secretion in astrocytes by activating the Shh signaling pathway. CONCLUSIONS Overall, the data presented in this study showed that ESP of fifth-stage larval A. cantonensis stimulates astrocyte activation and cytokine generation through NF-κB and the Shh signaling pathway.
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Affiliation(s)
- Kuang-Yao Chen
- Department of Parasitology, College of Medicine, Chang Gung University, Taoyuan, 333, Taiwan
| | - Lian-Chen Wang
- Department of Parasitology, College of Medicine, Chang Gung University, Taoyuan, 333, Taiwan. .,Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, 333, Taiwan. .,Molecular Infectious Disease Research Centre, Chang Gung Memorial Hospital, Taoyuan, Taiwan.
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Feola J, Barton A, Akbar A, Keillor J, Johnson GVW. Transglutaminase 2 modulation of NF-κB signaling in astrocytes is independent of its ability to mediate astrocytic viability in ischemic injury. Brain Res 2017; 1668:1-11. [PMID: 28522262 DOI: 10.1016/j.brainres.2017.05.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 04/14/2017] [Accepted: 05/10/2017] [Indexed: 12/20/2022]
Abstract
Transglutaminase 2 (TG2) is a multifunctional protein that can contribute to cell death and cell survival processes in a variety of disease contexts. Within the brain, TG2 has been shown to promote cell death in ischemic injury when expressed in astrocytes (Colak and Johnson, 2012). However, the specific functions and characteristics of astrocytic TG2 that mediate this effect are largely unknown. Therefore, the goal of this study was to investigate the role of astrocytic TG2 in mediating cellular viability processes in the context of ischemic injury, with a specific focus on its contributions to intracellular signaling cascades. We show that, in response to oxygen/glucose deprivation (OGD), acute lentiviral-mediated knockdown of TG2, as well as inhibition with an irreversible TG2 inhibitor, enhances cell survival. We also show that TG2 depletion increases nuclear factor-κB (NF-κB) signaling, whereas inhibition reduces NF-κB activity. Despite its clear contribution to NF-κB signaling, however, TG2 modulation of NF-κB signaling is not likely to be a major contributor to its ability to mediate astrocytic viability in this context. Overall, the results of this study provide insight into the role of TG2 in astrocytes and suggest possible avenues for future study of the relationship between astrocytic TG2 and ischemic injury.
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21
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Jantas D, Gręda A, Gołda S, Korostyński M, Lasoń W. The neuroprotective effects of orthosteric agonists of group II and III mGluRs in primary neuronal cell cultures are dependent on developmental stage. Neuropharmacology 2016; 111:195-211. [PMID: 27600687 DOI: 10.1016/j.neuropharm.2016.09.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 08/12/2016] [Accepted: 09/02/2016] [Indexed: 11/22/2022]
Abstract
Activation of metabotropic glutamate receptors (mGluRs) modulates neuronal excitability. Here, we evaluated the neuroprotective potential of four structurally diverse activators of group II and III mGluRs: an orthosteric agonist of group II (LY354740), an orthosteric agonist of group III (ACPT-I), an allosteric agonist of mGluR7 (AMN082) and a positive allosteric modulator (PAM) of mGluR4 (VU0361737). Neurotoxicity was induced by the pro-apoptotic agents: staurosporine (St) and doxorubicin (Dox) or the excitotoxic factor glutamate (Glu). The effects were analyzed in primary hippocampal (HIP) and cerebellar granule cell (CGC) cultures at two developmental stages, at 7 and 12 days in vitro (DIV). The data reveal a general neuroprotective effect of group II and III mGluR activators against the St- and Glu- but not Dox-induced cell damage. We found that neuroprotective effects of group II and III mGluR orthosteric agonists (LY354740 and ACPT-I) were higher at 12 DIV when compared to 7 DIV cells. In contrast, the efficiency of allosteric mGluR agents (AMN082 and VU0361737) did not differ between 7 and 12 DIV in both, St and Glu models of neuronal cell damage. Interestingly, the protective effects of activators of group II and III mGluRs were blocked by relevant antagonists only against Glu-induced neurotoxicity. Moreover, the observed neuroprotective action of group II and III mGluR activators in the St model was associated with a decreased number of PI-positive cells and no alterations in the caspase-3 activity. Finally, we showed that MAPK/ERK pathway activation was potentially involved in the mechanism of ACPT-I- and AMN082-induced neuroprotection against the St-evoked cellular damage. Our comparative study demonstrated the developmental stage-dependent neuroprotective effect of orthosteric group II and III mGluR agonists. In comparison to allosteric modulators, orthosteric compounds may provide more specific tools for suppression of neuronal cell loss associated with various chronic neurodegenerative conditions. Our results also suggest that the inhibition of intracellular pathways mediating necrotic, rather than apoptotic cascades, may be involved in neuroprotective effects of activators of group II and III mGluRs.
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22
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Martinez-Lozada Z, Guillem AM, Robinson MB. Transcriptional Regulation of Glutamate Transporters: From Extracellular Signals to Transcription Factors. Adv Pharmacol 2016; 76:103-45. [PMID: 27288076 DOI: 10.1016/bs.apha.2016.01.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Glutamate is the predominant excitatory neurotransmitter in the mammalian CNS. It mediates essentially all rapid excitatory signaling. Dysfunction of glutamatergic signaling contributes to developmental, neurologic, and psychiatric diseases. Extracellular glutamate is cleared by a family of five Na(+)-dependent glutamate transporters. Two of these transporters (GLAST and GLT-1) are relatively selectively expressed in astrocytes. Other of these transporters (EAAC1) is expressed by neurons throughout the nervous system. Expression of the last two members of this family (EAAT4 and EAAT5) is almost exclusively restricted to specific populations of neurons in cerebellum and retina, respectively. In this review, we will discuss our current understanding of the mechanisms that control transcriptional regulation of the different members of this family. Over the last two decades, our understanding of the mechanisms that regulate expression of GLT-1 and GLAST has advanced considerably; several specific transcription factors, cis-elements, and epigenetic mechanisms have been identified. For the other members of the family, little or nothing is known about the mechanisms that control their transcription. It is assumed that by defining the mechanisms involved, we will advance our understanding of the events that result in cell-specific expression of these transporters and perhaps begin to define the mechanisms by which neurologic diseases are changing the biology of the cells that express these transporters. This approach might provide a pathway for developing new therapies for a wide range of essentially untreatable and devastating diseases that kill neurons by an excitotoxic mechanism.
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Affiliation(s)
- Z Martinez-Lozada
- Children's Hospital of Philadelphia Research Institute, University of Pennsylvania, Philadelphia, PA, United States
| | - A M Guillem
- Children's Hospital of Philadelphia Research Institute, University of Pennsylvania, Philadelphia, PA, United States
| | - M B Robinson
- Children's Hospital of Philadelphia Research Institute, University of Pennsylvania, Philadelphia, PA, United States.
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Peterlik D, Flor PJ, Uschold-Schmidt N. The Emerging Role of Metabotropic Glutamate Receptors in the Pathophysiology of Chronic Stress-Related Disorders. Curr Neuropharmacol 2016; 14:514-39. [PMID: 27296643 PMCID: PMC4983752 DOI: 10.2174/1570159x13666150515234920] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2015] [Revised: 04/04/2015] [Accepted: 05/12/2015] [Indexed: 12/28/2022] Open
Abstract
Chronic stress-related psychiatric conditions such as anxiety, depression, and alcohol abuse are an enormous public health concern. The etiology of these pathologies is complex, with psychosocial stressors being among the most frequently discussed risk factors. The brain glutamatergic neurotransmitter system has often been found involved in behaviors and pathophysiologies resulting from acute stress and fear. Despite this, relatively little is known about the role of glutamatergic system components in chronic psychosocial stress, neither in rodents nor in humans. Recently, drug discovery efforts at the metabotropic receptor subtypes of the glutamatergic system (mGlu1-8 receptors) led to the identification of pharmacological tools with emerging potential in psychiatric conditions. But again, the contribution of individual mGlu subtypes to the manifestation of physiological, molecular, and behavioral consequences of chronic psychosocial stress remains still largely unaddressed. The current review will describe animal models typically used to analyze acute and particularly chronic stress conditions, including models of psychosocial stress, and there we will discuss the emerging roles for mGlu receptor subtypes. Indeed, accumulating evidence indicates relevance and potential therapeutic usefulness of mGlu2/3 ligands and mGlu5 receptor antagonists in chronic stress-related disorders. In addition, a role for further mechanisms, e.g. mGlu7-selective compounds, is beginning to emerge. These mechanisms are important to be analyzed in chronic psychosocial stress paradigms, e.g. in the chronic subordinate colony housing (CSC) model. We summarize the early results and discuss necessary future investigations, especially for mGlu5 and mGlu7 receptor blockers, which might serve to suggest improved therapeutic strategies to treat stress-related disorders.
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Affiliation(s)
| | - Peter J Flor
- Faculty of Biology and Preclinical Medicine, University of Regensburg, D-93053 Regensburg, Germany.
| | - Nicole Uschold-Schmidt
- Faculty of Biology and Preclinical Medicine, University of Regensburg, D-93053 Regensburg, Germany.
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Jantas D, Greda A, Leskiewicz M, Grygier B, Pilc A, Lason W. Neuroprotective effects of mGluR II and III activators against staurosporine- and doxorubicin-induced cellular injury in SH-SY5Y cells: New evidence for a mechanism involving inhibition of AIF translocation. Neurochem Int 2015; 88:124-37. [PMID: 25661514 DOI: 10.1016/j.neuint.2014.12.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Revised: 12/06/2014] [Accepted: 12/28/2014] [Indexed: 12/12/2022]
Abstract
There are several experimental data sets demonstrating the neuroprotective effects of activation of group II and III metabotropic glutamate receptors (mGluR II/III), however, their effect on neuronal apoptotic processes has yet to be fully recognized. Thus, the comparison of the neuroprotective potency of the mGluR II agonist LY354740, mGluR III agonist ACPT-I, mGluR4 PAM VU0361737, mGluR8 PAM AZ12216052 and allosteric mGluR7 agonist AMN082 against staurosporine (St-) and doxorubicin (Dox)-induced cell death has been performed in undifferentiated (UN-) and retinoic acid differentiated (RA-) human neuroblastoma SH-SY5Y cells. The highest neuroprotection in UN-SH-SY5Y cells was noted for AZ12216052 (0.01-1 µM) and VU0361737 (1-10 µM), with both agents partially attenuating the St- and Dox-evoked cell death. LY354740 (0.01-10 µM) and ACPT-I (10 µM) were protective only against the St-evoked cell damage, whereas AMN082 (0.001-0.01 µM) attenuated only the Dox-induced cell death. In RA-SH-SY5Y, a moderate neuroprotective response of mGluR II/III activators was observed for LY354740 (10 µM) and AZ12216052 (0.01 and 10 µM), which afforded protection only against the St-induced cell damage. The protection mediated by mGluR II/III activators against the St- and Dox-evoked cell death in UN-SH-SY5Y cells was not related to attenuation of caspase-3 activity, however, a decrease in the number of TUNEL-positive nuclei was found. Moreover, mGluR II/III activators attenuated the cytosolic level of the apoptosis inducing factor (AIF), which was increased after St and Dox exposure. Our data point to differential neuroprotective efficacy of various mGluR II/III activators in attenuating St- and Dox-evoked cell damage in SH-SY5Y cells, and dependence of the effects on the cellular differentiation state, as well on the type of the pro-apoptotic agent that is employed. Moreover, the neuroprotection mediated by mGluR II/III activators is accompanied by inhibition of caspase-3-independent DNA fragmentation evoked by AIF translocation.
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Affiliation(s)
- D Jantas
- Department of Experimental Neuroendocrinology, Polish Academy of Sciences, Smetna 12 Street, Krakow PL 31-343, Poland.
| | - A Greda
- Department of Experimental Neuroendocrinology, Polish Academy of Sciences, Smetna 12 Street, Krakow PL 31-343, Poland
| | - M Leskiewicz
- Department of Experimental Neuroendocrinology, Polish Academy of Sciences, Smetna 12 Street, Krakow PL 31-343, Poland
| | - B Grygier
- Department of Experimental Neuroendocrinology, Polish Academy of Sciences, Smetna 12 Street, Krakow PL 31-343, Poland
| | - A Pilc
- Department of Neurobiology, Institute of Pharmacology, Polish Academy of Sciences, Smetna 12 Street, Krakow PL 31-343, Poland
| | - W Lason
- Department of Experimental Neuroendocrinology, Polish Academy of Sciences, Smetna 12 Street, Krakow PL 31-343, Poland
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