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Liu CH, Liao WC, Li HH, Tseng LH, Wang WH, Tung H, Lin PJ, Jao HT, Liu WY, Hung CS, Lin CL, Ho YJ. Treatment with the combination of clavulanic acid and valproic acid led to recovery of neuronal and behavioral deficits in an epilepsy rat model. Fundam Clin Pharmacol 2021; 35:1032-1044. [PMID: 34545633 DOI: 10.1111/fcp.12729] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 09/17/2021] [Indexed: 01/09/2023]
Abstract
Epilepsy, which is caused by abnormal neuronal firing in the brain, is a common neurological disease and affects motor and cognitive functions. Excessive levels of glutamate and insufficient levels of inhibitory GABA are involved in its pathophysiology. Valproic acid (Val), a GABAergic agonist, is one of the first-line antiepileptic drugs, but it shows many adverse side effects at the clinical dose. Clavulanic acid (CA), a β-lactamase inhibitor, has been demonstrated to increase glutamate transporter-1 expression. This study evaluated the effects of CA and Val in an epilepsy rat model. Male Wistar rats received intraperitoneal injections of pentylenetetrazol (PTZ, 35 mg/kg, every other day, IP, for 13 days) to induce kindling epilepsy. After four times of PTZ injection, rats received daily treatment with CA (1 or 10 mg/kg, IP), Val (50 or 100 mg/kg, IP), or the combination of CA (1 mg/kg) and Val (50 mg/kg) for 7 consecutive days. Motor, learning, and memory functions were measured. Rats with PTZ-induced kindling exhibited seizures, motor dysfunction, cognitive impairment, and cell loss and reduction of neurogenesis in the hippocampus. Neither 1 mg/kg CA nor 50 mg/kg Val treatment was effective in alleviating behavioral and neuronal deficits. However, treatment with 10 mg/kg CA, 100 mg/kg Val, and the combination of 1 mg/kg CA and 50 mg/kg Val improved these behavioral and neuronal deficits. Particularly, the combination of CA and Val showed synergistic effects on seizure suppression, suggesting the potential for treating epilepsy and related neuronal damage and motor and cognitive deficits.
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Affiliation(s)
- Chiung-Hui Liu
- Department of Anatomy, Faculty of Medicine, Chung Shan Medical University, Taichung, Taiwan
| | - Wen-Chieh Liao
- Department of Anatomy, Faculty of Medicine, Chung Shan Medical University, Taichung, Taiwan
| | - Hsin-Hua Li
- General Education Center, National Taiwan University of Sport, Taichung, Taiwan
| | - Li-Ho Tseng
- Graduate School of Environmental Management, Tajen University, Pingtung, Taiwan
| | - Wei-Han Wang
- Department of Psychology, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Hsin Tung
- Center of Faculty Development; Division of Epilepsy, Neurological Institute, Taichung Veterans General Hospital, Taichung, Taiwan
| | - Pin-Jiun Lin
- Department of Psychology, Chung Shan Medical University Hospital, Chung Shan Medical University, Taichung, Taiwan
| | - Hsin-Tung Jao
- Department of Psychology, Chung Shan Medical University Hospital, Chung Shan Medical University, Taichung, Taiwan
| | - Wen-Yuan Liu
- Department of Psychology, Chung Shan Medical University Hospital, Chung Shan Medical University, Taichung, Taiwan
| | - Ching-Sui Hung
- Occupational Safety and Health Office, Taipei City Hospital, Taipei, Taiwan
| | - Chih-Li Lin
- Institute of Medicine, Department of Medical Research, Chung Shan Medical University Hospital, Chung Shan Medical University, Taichung, Taiwan
| | - Ying-Jui Ho
- Department of Psychology, Chung Shan Medical University Hospital, Chung Shan Medical University, Taichung, Taiwan
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Li HH, Lin PJ, Wang WH, Tseng LH, Tung H, Liu WY, Lin CL, Liu CH, Liao WC, Hung CS, Ho YJ. Treatment effects of the combination of ceftriaxone and valproic acid on neuronal and behavioural functions in a rat model of epilepsy. Exp Physiol 2021; 106:1814-1828. [PMID: 34086374 DOI: 10.1113/ep089624] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 06/03/2021] [Indexed: 01/29/2023]
Abstract
NEW FINDINGS What is the central question of this study? Imbalance of activities between GABAergic and glutamatergic systems is involved in epilepsy. It is not known whether simultaneously increasing GABAergic and decreasing glutamatergic activity using valproic acid and ceftriaxone, respectively, leads to better seizure control. What is the central question of this study? Ceftriaxone suppressed seizure and cognitive deficits and restored neuronal density and the number of newborn cells in the hippocampus in a rat model of epilepsy. Combined treatment with ceftriaxone and valproic acid showed additive effects in seizure suppression. ABSTRACT The pathophysiology of epilepsy is typically considered as an imbalance between inhibitory GABA and excitatory glutamate neurotransmission. Valproic acid (Val), a GABA agonist, is one of the first-line antiepileptic drugs in the treatment of epilepsy, but it exhibits adverse effects. Ceftriaxone (CEF) elevates expression of glutamate transporter-1, enhances the reuptake of synaptic glutamate, increases the number of newborn cells and exhibits neuroprotective effects in animal studies. In this study, we evaluated effects of the combination of CEF and Val on behavioural and neuronal measures in a rat epilepsy model. Male Wistar rats were injected i.p. with pentylenetetrazol (35 mg/kg, every other day for 13 days) to induce the epilepsy model. Ceftriaxone (10 or 50 mg/kg), Val (50 or 100 mg/kg) or the combination of CEF and Val were injected daily after the fourth pentylenetetrazol injection for seven consecutive days. Epileptic rats exhibited seizure and impairments in motor and cognitive functions. Treatment with CEF and Val reduced the seizure and enhanced motor and cognitive functions in a dose-dependent manner. The combination of CEF (10 mg/kg) and Val (50 mg/kg) improved behaviours considerably. Histologically, compared with control animals, epileptic rats exhibited lower neuronal density and a reduction in hippocampal newborn cells but higher apoptosis in the basolateral amygdala, all of which were restored by the treatment with CEF, Val or the combination of CEF and Val. The study findings demonstrated that the combination of low doses of CEF and Val has beneficial effects on seizure suppression, neuroprotection and improvement in motor and cognitive functions in epilepsy.
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Affiliation(s)
- Hsin-Hua Li
- Department of Medical Research, Institute of Medicine, Chung Shan Medical University Hospital, Chung Shan Medical University, Taichung, Taiwan, Republic of China
| | - Pin-Jiun Lin
- Department of Psychology, Chung Shan Medical University Hospital, Chung Shan Medical University, Taichung, Taiwan, Republic of China
| | - Wei-Han Wang
- Department of Psychology, Kaohsiung Medical University, Kaohsiung, Taiwan, Republic of China
| | - Li-Ho Tseng
- Graduate School of Environmental Management, Tajen University, Pingtung, Taiwan, Republic of China
| | - Hsin Tung
- Division of Epilepsy, Center of Faculty Development, Neurological Institute, Taichung Veterans General Hospital, Taichung, Taiwan, Republic of China
| | - Wen-Yuan Liu
- Department of Psychology, Chung Shan Medical University Hospital, Chung Shan Medical University, Taichung, Taiwan, Republic of China
| | - Chih-Li Lin
- Department of Medical Research, Institute of Medicine, Chung Shan Medical University Hospital, Chung Shan Medical University, Taichung, Taiwan, Republic of China
| | - Chiung-Hui Liu
- Department of Anatomy, Faculty of Medicine, Chung Shan Medical University, Taichung, Taiwan, Republic of China
| | - Wen-Chieh Liao
- Department of Anatomy, Faculty of Medicine, Chung Shan Medical University, Taichung, Taiwan, Republic of China
| | - Ching-Sui Hung
- Occupational Safety and Health Office, Taipei City Hospital, Taipei, Taiwan, Republic of China
| | - Ying-Jui Ho
- Department of Psychology, Chung Shan Medical University Hospital, Chung Shan Medical University, Taichung, Taiwan, Republic of China
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3
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Wilkie CM, Barron JC, Brymer KJ, Barnes JR, Nafar F, Parsons MP. The Effect of GLT-1 Upregulation on Extracellular Glutamate Dynamics. Front Cell Neurosci 2021; 15:661412. [PMID: 33841104 PMCID: PMC8032948 DOI: 10.3389/fncel.2021.661412] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 03/05/2021] [Indexed: 12/21/2022] Open
Abstract
Pharmacological upregulation of glutamate transporter-1 (GLT-1), commonly achieved using the beta-lactam antibiotic ceftriaxone, represents a promising therapeutic strategy to accelerate glutamate uptake and prevent excitotoxic damage in neurological conditions. While excitotoxicity is indeed implicated in numerous brain diseases, it is typically restricted to select vulnerable brain regions, particularly in early disease stages. In healthy brain tissue, the speed of glutamate uptake is not constant and rather varies in both an activity- and region-dependent manner. Despite the widespread use of ceftriaxone in disease models, very little is known about how such treatments impact functional measures of glutamate uptake in healthy tissue, and whether GLT-1 upregulation can mask the naturally occurring activity-dependent and regional heterogeneities in uptake. Here, we used two different compounds, ceftriaxone and LDN/OSU-0212320 (LDN), to upregulate GLT-1 in healthy wild-type mice. We then used real-time imaging of the glutamate biosensor iGluSnFR to investigate functional consequences of GLT-1 upregulation on activity- and regional-dependent variations in glutamate uptake capacity. We found that while both ceftriaxone and LDN increased GLT-1 expression in multiple brain regions, they did not prevent activity-dependent slowing of glutamate clearance nor did they speed basal clearance rates, even in areas characterized by slow uptake (e.g., striatum). Unexpectedly, ceftriaxone but not LDN decreased glutamate release in the cortex, suggesting that ceftriaxone may alter release properties independent of its effects on GLT-1 expression. In sum, our data demonstrate the complexities of glutamate uptake by showing that GLT-1 expression does not necessarily translate to accelerated uptake. Furthermore, these data suggest that the mechanisms underlying activity- and regional-dependent differences in glutamate dynamics are independent of GLT-1 expression levels.
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Affiliation(s)
- Crystal M Wilkie
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University, St. John's, NL, Canada
| | - Jessica C Barron
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University, St. John's, NL, Canada
| | - Kyle J Brymer
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University, St. John's, NL, Canada
| | - Jocelyn R Barnes
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University, St. John's, NL, Canada
| | - Firoozeh Nafar
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University, St. John's, NL, Canada
| | - Matthew P Parsons
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University, St. John's, NL, Canada
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Shoshan-Barmatz V, Krelin Y, Shteinfer-Kuzmine A. VDAC1 functions in Ca 2+ homeostasis and cell life and death in health and disease. Cell Calcium 2017; 69:81-100. [PMID: 28712506 DOI: 10.1016/j.ceca.2017.06.007] [Citation(s) in RCA: 97] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 06/21/2017] [Accepted: 06/21/2017] [Indexed: 01/15/2023]
Abstract
In the outer mitochondrial membrane (OMM), the voltage-dependent anion channel 1 (VDAC1) serves as a mitochondrial gatekeeper, controlling the metabolic and energy cross-talk between mitochondria and the rest of the cell. VDAC1 also functions in cellular Ca2+ homeostasis by transporting Ca2+ in and out of mitochondria. VDAC1 has also been recognized as a key protein in mitochondria-mediated apoptosis, contributing to the release of apoptotic proteins located in the inter-membranal space (IMS) and regulating apoptosis via association with pro- and anti-apoptotic members of the Bcl-2 family of proteins and hexokinase. VDAC1 is highly Ca2+-permeable, transporting Ca2+ to the IMS and thus modulating Ca2+ access to Ca2+ transporters in the inner mitochondrial membrane. Intra-mitochondrial Ca2+ controls energy metabolism via modulating critical enzymes in the tricarboxylic acid cycle and in fatty acid oxidation. Ca2+ also determines cell sensitivity to apoptotic stimuli and promotes the release of pro-apoptotic proteins. However, the precise mechanism by which intracellular Ca2+ mediates apoptosis is not known. Here, the roles of VDAC1 in mitochondrial Ca2+ homeostasis are presented while emphasizing a new proposed mechanism for the mode of action of pro-apoptotic drugs. This view, proposing that Ca2+-dependent enhancement of VDAC1 expression levels is a major mechanism by which apoptotic stimuli induce apoptosis, position VDAC1 oligomerization at a molecular focal point in apoptosis regulation. The interactions of VDAC1 with many proteins involved in Ca2+ homeostasis or regulated by Ca2+, as well as VDAC-mediated control of cell life and death and the association of VDAC with disease, are also presented.
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Affiliation(s)
- Varda Shoshan-Barmatz
- Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel.
| | - Yakov Krelin
- Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Anna Shteinfer-Kuzmine
- Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
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5
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Butt AM, Vanzulli I, Papanikolaou M, De La Rocha IC, Hawkins VE. Metabotropic Glutamate Receptors Protect Oligodendrocytes from Acute Ischemia in the Mouse Optic Nerve. Neurochem Res 2017; 42:2468-2478. [PMID: 28365868 PMCID: PMC5603641 DOI: 10.1007/s11064-017-2220-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 02/13/2017] [Accepted: 02/28/2017] [Indexed: 12/01/2022]
Abstract
Studies by Bruce Ransom and colleagues have made a major contribution to show that white matter is susceptible to ischemia/hypoxia. White matter contains axons and the glia that support them, notably myelinating oligodendrocytes, which are highly vulnerable to ischemic-hypoxic damage. Previous studies have shown that metabotropic GluRs (mGluRs) are cytoprotective for oligodendrocyte precursor cells and immature oligodendrocytes, but their potential role in adult white matter was unresolved. Here, we report that group 1 mGluR1/5 and group 2 mGluR3 subunits are expressed in optic nerves from mice aged postnatal day (P)8-12 and P30-35. We demonstrate that activation of group 1 mGluR protects oligodendrocytes against oxygen-glucose deprivation (OGD) in developing and young adult optic nerves. In contrast, group 2 mGluR are shown to be protective for oligodendrocytes against OGD in postnatal but not young adult optic nerves. The cytoprotective effect of group 1 mGluR requires activation of PKC, whilst group 2 mGluR are dependent on negatively regulating adenylyl cyclase and cAMP. Our results identify a role for mGluR in limiting injury of oligodendrocytes in developing and young adult white matter, which may be useful for protecting oligodendrocytes in neuropathologies involving excitoxicity and ischemia/hypoxia.
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Affiliation(s)
- Arthur M Butt
- Institute of Biomedical and Biomolecular Sciences, School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth, UK.
| | - Ilaria Vanzulli
- Institute of Biomedical and Biomolecular Sciences, School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth, UK
| | - Maria Papanikolaou
- Institute of Biomedical and Biomolecular Sciences, School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth, UK
| | - Irene Chacon De La Rocha
- Institute of Biomedical and Biomolecular Sciences, School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth, UK
| | - Virginia E Hawkins
- Institute of Biomedical and Biomolecular Sciences, School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth, UK. .,Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, 06269, USA.
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6
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Huff CL, Morano RL, Herman JP, Yamamoto BK, Gudelsky GA. MDMA decreases glutamic acid decarboxylase (GAD) 67-immunoreactive neurons in the hippocampus and increases seizure susceptibility: Role for glutamate. Neurotoxicology 2016; 57:282-290. [PMID: 27773601 DOI: 10.1016/j.neuro.2016.10.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Revised: 10/17/2016] [Accepted: 10/18/2016] [Indexed: 01/15/2023]
Abstract
3,4-Methylenedioxy-methamphetamine (MDMA) is a unique psychostimulant that continues to be a popular drug of abuse. It has been well documented that MDMA reduces markers of 5-HT axon terminals in rodents, as well as humans. A loss of parvalbumin-immunoreactive (IR) interneurons in the hippocampus following MDMA treatment has only been documented recently. In the present study, we tested the hypothesis that MDMA reduces glutamic acid decarboxylase (GAD) 67-IR, another biochemical marker of GABA neurons, in the hippocampus and that this reduction in GAD67-IR neurons and an accompanying increase in seizure susceptibility involve glutamate receptor activation. Repeated exposure to MDMA (3×10mg/kg, ip) resulted in a reduction of 37-58% of GAD67-IR cells in the dentate gyrus (DG), CA1, and CA3 regions, as well as an increased susceptibility to kainic acid-induced seizures, both of which persisted for at least 30days following MDMA treatment. Administration of the NMDA antagonist MK-801 or the glutamate transporter type 1 (GLT-1) inducer ceftriaxone prevented both the MDMA-induced loss of GAD67-IR neurons and the increased vulnerability to kainic acid-induced seizures. The MDMA-induced increase in the extracellular concentration of glutamate in the hippocampus was significantly diminished in rats treated with ceftriaxone, thereby implicating a glutamatergic mechanism in the neuroprotective effects of ceftriaxone. In summary, the present findings support a role for increased extracellular glutamate and NMDA receptor activation in the MDMA-induced loss of hippocampal GAD67-IR neurons and the subsequent increased susceptibility to evoked seizures.
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Affiliation(s)
- Courtney L Huff
- Division of Pharmaceutical Sciences, University of Cincinnati-James Winkle College of Pharmacy, Cincinnati, OH 45267, United States
| | - Rachel L Morano
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati-College of Medicine, Cincinnati, OH, 45219, United States
| | - James P Herman
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati-College of Medicine, Cincinnati, OH, 45219, United States
| | - Bryan K Yamamoto
- Department of Pharmacology and Toxicology, Indiana University-School of Medicine, Indianapolis, IN 46202, United States
| | - Gary A Gudelsky
- Division of Pharmaceutical Sciences, University of Cincinnati-James Winkle College of Pharmacy, Cincinnati, OH 45267, United States.
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Sulforaphane Prevents Methylmercury-Induced Oxidative Damage and Excitotoxicity Through Activation of the Nrf2-ARE Pathway. Mol Neurobiol 2016; 54:375-391. [PMID: 26742517 DOI: 10.1007/s12035-015-9643-y] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 12/16/2015] [Indexed: 12/29/2022]
Abstract
Methylmercury (MeHg) is a prominent environmental neurotoxicant, which induces oxidative damage and an indirect excitotoxicity caused by altered glutamate (Glu) metabolism. However, the interaction between oxidative damage and excitotoxicity in MeHg-exposed rats has not been fully recognized. Here, we explored the interaction between oxidative damage and excitotoxicity and evaluated the preventive effects of sulforaphane (SFN) on MeHg-induced neurotoxicity in rat cerebral cortex. Seventy-two rats were randomly assigned to four groups: control group, MeHg-treated groups (4 and 12 μmol/kg), and SFN pretreatment group. After treatment (28 days), the rats were killed and the cerebral cortex was analyzed. Then, Hg, glutathione (GSH), malondialdehyde (MDA), protein sulfhydryl, protein carbonyl, 8-hydroxy-2-deoxyguanosine (8-OHdG), and the levels of reactive oxygen species (ROS) and apoptosis were examined. Glu and glutamine (Gln) levels, glutamine synthetase (GS), phosphate-activated glutaminase (PAG), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), Na+-K+-ATPase and Ca2+-ATPase activities, intracellular Ca2+ levels, and the mRNA and protein expressions of Nrf2, Nrf2-regulated gene products, and N-methyl-D-aspartate receptors (NMDARs) were investigated in rat cerebral cortex. In our study, MeHg exposure not only induced Hg accumulation, apoptosis, ROS formation, GSH depletion, inhibition of antioxidant enzyme activities, and activation of Nrf2-ARE pathway signaling but also caused lipid, protein, and DNA peroxidative damage in a dose-dependent manner in rat cerebral cortex. Moreover, MeHg treatment significantly altered Gln/Glu cycling and NMDAR expression and resulted in calcium overloading. Furthermore, the present study also indicated that SFN pretreatment significantly reinforced the activation of the Nrf2-ARE pathway, which could prevent the toxic effects of MeHg exposure. Collectively, MeHg initiates multiple additive or synergistic disruptive mechanisms that lead to oxidative damage and excitotoxicity in rat cerebral cortex; pretreatment with SFN might prevent the MeHg-induced neurotoxicity by reinforcing the activation of the Nrf2-ARE pathway and then downregulating the interaction between oxidative damage and excitotoxicity pathways.
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8
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mGluR5 protect astrocytes from ischemic damage in postnatal CNS white matter. Cell Calcium 2015; 58:423-30. [PMID: 26189008 PMCID: PMC4634333 DOI: 10.1016/j.ceca.2015.06.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2015] [Revised: 06/26/2015] [Accepted: 06/28/2015] [Indexed: 11/21/2022]
Abstract
Astrocytes perform essential neuron-supporting functions in the central nervous system (CNS) and their disruption has devastating effects on neuronal integrity in multiple neuropathologies. Although astrocytes are considered resistant to most pathological insults, ischemia can result in astrocyte injury and astrocytes in postnatal white matter are particularly vulnerable. Metabotropic glutamate receptors (mGluR) are neuroprotective in ischemia and are widely expressed by astrocytes throughout CNS grey matter, but their potential cytoprotective role in astrocytes had not been determined. Here, we identify functional expression of group I mGluR in white matter astrocytes and demonstrate their activation protects astrocytes from ischemic damage in the postnatal mouse optic nerve. Optic nerve astrocytes are shown to express mGluR5 using immunolabelling of sections and explant cultures from transgenic reporter mice in which GFAP drives expression of EGFP. In addition, using Fluo-4 calcium imaging in isolated intact optic nerves, we show that the group I/II mGluR agonist ACPD and the specific group I mGluR agonist DHPG evoke glial Ca(2+) signals that were significantly inhibited by the group I mGluR antagonist AIDA. A key finding is that activation of group I mGluR protects astrocytes against oxygen-glucose deprivation (OGD) in situ, in isolated intact optic nerves from GFAP-EGFP mice. This study identifies a role for group I mGluR in protecting astrocytes against ischemia in postnatal white matter and suggests this may be a strategy for limiting damage in neuropathologies involving excitotoxity.
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Cui X, Li L, Hu YY, Ren S, Zhang M, Li WB. Sulbactam Plays Neuronal Protective Effect Against Brain Ischemia via Upregulating GLT1 in Rats. Mol Neurobiol 2014; 51:1322-33. [DOI: 10.1007/s12035-014-8809-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Accepted: 07/10/2014] [Indexed: 11/25/2022]
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10
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Exploring cross-talk between oxidative damage and excitotoxicity and the effects of riluzole in the rat cortex after exposure to methylmercury. Neurotox Res 2014; 26:40-51. [PMID: 24519665 DOI: 10.1007/s12640-013-9448-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2013] [Revised: 11/07/2013] [Accepted: 12/05/2013] [Indexed: 12/22/2022]
Abstract
Methylmercury (MeHg) is a ubiquitous environmental toxin that causes neurologic and developmental diseases. Oxidative damage and excitotoxicity are putative mechanisms, which underlie MeHg-induced neurotoxicity. In this study, the cross-talk between the oxidative damage and excitotoxicity pathways and the protective effects of riluzole in the rat cortex were explored. Rats were injected with MeHg and/or riluzole, and cold vapor atomic fluorescence spectrometry, hematoxylin and eosin staining, flow cytometry, fluorescence assays, spectrophotometry, real-time PCR, and Western blotting were used to evaluate neurotoxicity. The present study showed that (1) MeHg accumulated in the cerebral cortex and caused pathology. (2) MeHg caused oxidative damage by inducing glutathione (GSH) depletion, reactive oxygen species (ROS) production, inhibition of antioxidant enzyme activity, and alteration of the nuclear factor erythroid 2-related factor 2 (Nrf2) signaling. (3) MeHg disrupted the glutamate transporters (GluTs), glutamate-glutamine cycle, and N-methyl-D-aspartate receptor expression and induced excitotoxicity. (4) Excitotoxicity resulted in disruption of GSH synthesis, calcium overloading, oxidative damage, and excessive ROS production. (5) Pretreatment with riluzole antagonized MeHg neurotoxicity by down regulating cross-talk between the oxidative damage and excitotoxicity pathways. In conclusion, the cross-talk between the oxidative damage and excitotoxicity pathways caused by MeHg exposure was linked by GluTs and calcium and inhibited by riluzole treatment.
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11
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Russo R, Cavaliere F, Varano GP, Milanese M, Adornetto A, Nucci C, Bonanno G, Morrone LA, Corasaniti MT, Bagetta G. Impairment of neuronal glutamate uptake and modulation of the glutamate transporter GLT-1 induced by retinal ischemia. PLoS One 2013; 8:e69250. [PMID: 23936321 PMCID: PMC3735546 DOI: 10.1371/journal.pone.0069250] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Accepted: 06/06/2013] [Indexed: 01/09/2023] Open
Abstract
Excitotoxicity has been implicated in the retinal neuronal loss in several ocular pathologies including glaucoma. Dysfunction of Excitatory Amino Acid Transporters is often a key component of the cascade leading to excitotoxic cell death. In the retina, glutamate transport is mainly operated by the glial glutamate transporter GLAST and the neuronal transporter GLT-1. In this study we evaluated the expression of GLAST and GLT-1 in a rat model of acute glaucoma based on the transient increase of intraocular pressure (IOP) and characterized by high glutamate levels during the reperfusion that follows the ischemic event associated with raised IOP. No changes were reported in GLAST expression while, at neuronal level, a reduction of glutamate uptake and of transporter reversal-mediated glutamate release was observed in isolated retinal synaptosomes. This was accompanied by modulation of GLT-1 expression leading to the reduction of the canonical 65 kDa form and upregulation of a GLT-1-related 38 kDa protein. These results support a role for neuronal transporters in glutamate accumulation observed in the retina following an ischemic event and suggest the presence of a GLT-1 neuronal new alternative splice variant, induced in response to the detrimental stimulus.
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Affiliation(s)
- Rossella Russo
- Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Arcavacata di Rende, Italy.
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12
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Histamine up-regulates astrocytic glutamate transporter 1 and protects neurons against ischemic injury. Neuropharmacology 2013; 77:156-66. [PMID: 23791559 DOI: 10.1016/j.neuropharm.2013.06.012] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Revised: 05/13/2013] [Accepted: 06/06/2013] [Indexed: 11/22/2022]
Abstract
Astrocytic glutamate transporter 1 (GLT-1) is responsible for the majority of extracellular glutamate clearance and is essential for preventing excitotoxicity in the brain. Up-regulation of GLT-1 shows benefit effect on ischemia-induced neuronal damage. In present study, we examined the effect of histamine, a neurotransmitter or neuromodulator, on GLT-1 expression and function. In acute hippocampal slices, histamine selectively increased GLT-1 expression independent of neuronal activities. Similar up-regulation of GLT-1 was also observed after histamine treatment in pure cultured astrocytes, which was abolished by H1 receptor antagonist or PKC inhibitor. Cell surface biotinylation and whole-cell patch recordings of glutamate transporter current confirmed the up-regulation of functional GLT-1 following histamine exposure. Histamine treatment decreased the extracellular glutamate content and alleviated neuronal cell death induced by exogenous glutamate challenge. Moreover, we found a significant neuroprotective effect of histamine in brain slices after oxygen-glucose deprivation (OGD). In addition, histidine, the precursor of histamine, also showed neuroprotection against ischemic injury, which was accompanied by reversion of declined expression of GLT-1 in adult rats subjected to middle cerebral artery occlusion (MCAO). These neuroprotective effects of histamine/histidine were blocked by GLT-1 specific inhibitor dihydrokainate or H1 receptor antagonist. In summary, our results suggest that histamine up-regulates GLT-1 expression and function via astrocytic H1 receptors, thus resulting in neuroprotection against excitotoxicity and ischemic injury.
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