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Alotaibi A, Travaglianti S, Wong W, Abou-Gharbia M, Childers W, Sari Y. Effects of MC-100093 on Ethanol Drinking and the Expression of Astrocytic Glutamate Transporters in the Mesocorticolimbic Brain Regions of Male and Female Alcohol-Preferring Rats. Neuroscience 2024; 552:89-99. [PMID: 38909675 PMCID: PMC11407434 DOI: 10.1016/j.neuroscience.2024.06.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 06/12/2024] [Accepted: 06/18/2024] [Indexed: 06/25/2024]
Abstract
Chronic ethanol consumption increased extracellular glutamate concentrations in several reward brain regions. Glutamate homeostasis is regulated in majority by astrocytic glutamate transporter 1 (GLT-1) as well as the interactive role of cystine/glutamate antiporter (xCT). In this study, we aimed to determine the attenuating effects of a novel beta-lactam MC-100093, lacking the antibacterial properties, on ethanol consumption and GLT-1 and xCT expression in the subregions of nucleus accumbens (NAc core and NAc shell) and medial prefrontal cortex (Infralimbic, mPFC-IL and Prelimbic, mPFC-PL) in male and female alcohol-preferring (P) rats. Female and male rats were exposed to free access to ethanol (15% v/v) and (30% v/v) and water for five weeks, and on Week 6, rats were administered 100 mg/kg (i.p) of MC-100093 or saline for five days. MC-100093 reduced ethanol consumption in both male and female P rats from Day 1-5. Additionally, MC-100093 upregulated GLT-1 and xCT expression in the mPFC and NAc subregions as compared to ethanol-saline groups in female and male rats. Chronic ethanol intake reduced GLT-1 and xCT expression in the IL and PL in female and male rats, except there was no reduction in GLT-1 expression in the mPFC-PL in female rats. Although, MC-100093 upregulated GLT-1 and xCT expression in the subregions of NAc, we did not observe any reduction in GLT-1 and xCT expression with chronic ethanol intake in female rats. These findings strongly suggest that MC-100093 treatment effectively reduced ethanol intake and upregulated GLT-1 and xCT expression in the mPFC and NAc subregions in male and female P rats.
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Affiliation(s)
- Ahmed Alotaibi
- University of Toledo, College of Pharmacy and Pharmaceutical Sciences, Department of Pharmacology and Experimental Therapeutics, Toledo, OH 43614, USA
| | - Shelby Travaglianti
- University of Toledo, College of Pharmacy and Pharmaceutical Sciences, Department of Pharmacology and Experimental Therapeutics, Toledo, OH 43614, USA
| | - Woonyen Wong
- University of Toledo, College of Pharmacy and Pharmaceutical Sciences, Department of Pharmacology and Experimental Therapeutics, Toledo, OH 43614, USA
| | - Magid Abou-Gharbia
- Department of Pharmaceutical Sciences, Temple University School of Pharmacy, Philadelphia, PA 19140, USA
| | - Wayne Childers
- Department of Pharmaceutical Sciences, Temple University School of Pharmacy, Philadelphia, PA 19140, USA
| | - Youssef Sari
- University of Toledo, College of Pharmacy and Pharmaceutical Sciences, Department of Pharmacology and Experimental Therapeutics, Toledo, OH 43614, USA.
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2
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Luessen DJ, Conn PJ. Allosteric Modulators of Metabotropic Glutamate Receptors as Novel Therapeutics for Neuropsychiatric Disease. Pharmacol Rev 2022; 74:630-661. [PMID: 35710132 PMCID: PMC9553119 DOI: 10.1124/pharmrev.121.000540] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Metabotropic glutamate (mGlu) receptors, a family of G-protein-coupled receptors, have been identified as novel therapeutic targets based on extensive research supporting their diverse contributions to cell signaling and physiology throughout the nervous system and important roles in regulating complex behaviors, such as cognition, reward, and movement. Thus, targeting mGlu receptors may be a promising strategy for the treatment of several brain disorders. Ongoing advances in the discovery of subtype-selective allosteric modulators for mGlu receptors has provided an unprecedented opportunity for highly specific modulation of signaling by individual mGlu receptor subtypes in the brain by targeting sites distinct from orthosteric or endogenous ligand binding sites on mGlu receptors. These pharmacological agents provide the unparalleled opportunity to selectively regulate neuronal excitability, synaptic transmission, and subsequent behavioral output pertinent to many brain disorders. Here, we review preclinical and clinical evidence supporting the utility of mGlu receptor allosteric modulators as novel therapeutic approaches to treat neuropsychiatric diseases, such as schizophrenia, substance use disorders, and stress-related disorders.
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3
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Beckers P, Lara O, Belo do Nascimento I, Desmet N, Massie A, Hermans E. Validation of a System xc– Functional Assay in Cultured Astrocytes and Nervous Tissue Samples. Front Cell Neurosci 2022; 15:815771. [PMID: 35095428 PMCID: PMC8793334 DOI: 10.3389/fncel.2021.815771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 12/24/2021] [Indexed: 11/13/2022] Open
Abstract
Disruption of the glutamatergic homeostasis is commonly observed in neurological diseases and has been frequently correlated with the altered expression and/or function of astrocytic high-affinity glutamate transporters. There is, however, a growing interest for the role of the cystine-glutamate exchanger system xc– in controlling glutamate transmission. This exchanger is predominantly expressed in glial cells, especially in microglia and astrocytes, and its dysregulation has been documented in diverse neurological conditions. While most studies have focused on measuring the expression of its specific subunit xCT by RT-qPCR or by Western blotting, the activity of this exchanger in tissue samples remains poorly examined. Indeed, the reported use of sulfur- and carbon-radiolabeled cystine in uptake assays shows several drawbacks related to its short radioactive half-life and its relatively high cost. We here report on the elaborate validation of a method using tritiated glutamate as a substrate for the reversed transport mediated by system xc–. The uptake assay was validated in primary cultured astrocytes, in transfected cells as well as in crude synaptosomes obtained from fresh nervous tissue samples. Working in buffers containing defined concentrations of Na+, allowed us to differentiate the glutamate uptake supported by system xc– or by high-affinity glutamate transporters, as confirmed by using selective pharmacological inhibitors. The specificity was further demonstrated in primary astrocyte cultures from transgenic mice lacking xCT or in cell lines where xCT expression was genetically induced or reduced. As such, this assay appears to be a robust and cost-efficient solution to investigate the activity of this exchanger in physiological and pathological conditions. It also provides a reliable tool for the screening and characterization of new system xc– inhibitors which have been frequently cited as valuable drugs for nervous disorders and cancer.
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Affiliation(s)
- Pauline Beckers
- Group of Neuropharmacology, Institute of Neuroscience, Université catholique de Louvain, Brussels, Belgium
| | - Olaya Lara
- Neuro-Aging & Viro-Immunotherapy, Center for Neurosciences, Vrije Universiteit Brussel, Brussels, Belgium
| | - Ines Belo do Nascimento
- Group of Neuropharmacology, Institute of Neuroscience, Université catholique de Louvain, Brussels, Belgium
| | - Nathalie Desmet
- Group of Neuropharmacology, Institute of Neuroscience, Université catholique de Louvain, Brussels, Belgium
| | - Ann Massie
- Neuro-Aging & Viro-Immunotherapy, Center for Neurosciences, Vrije Universiteit Brussel, Brussels, Belgium
| | - Emmanuel Hermans
- Group of Neuropharmacology, Institute of Neuroscience, Université catholique de Louvain, Brussels, Belgium
- *Correspondence: Emmanuel Hermans,
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4
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Magdy S, Gamal M, Samir NF, Rashed L, Emad Aboulhoda B, Mohammed HS, Sharawy N. IκB kinase inhibition remodeled connexins, pannexin-1, and excitatory amino-acid transporters expressions to promote neuroprotection of galantamine and morphine. J Cell Physiol 2021; 236:7516-7532. [PMID: 33855721 DOI: 10.1002/jcp.30387] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 03/21/2021] [Accepted: 03/26/2021] [Indexed: 11/10/2022]
Abstract
Inflammatory pathway and disruption in glutamate homeostasis join at the level of the glia, resulting in various neurological disorders. In vitro studies have provided evidence that membrane proteins connexions (Cxs) are involved in glutamate release, meanwhile, excitatory amino-acid transporters (EAATs) are crucial for glutamate reuptake (clearance). Moreover, pannexin-1 (Panx-1) activation is more detrimental to neurons. Their expression patterns during inflammation and the impacts of IκB kinase (IKK) inhibition, morphine, and galantamine on the inflammatory-associated glutamate imbalance remain elusive. To investigate this, rats were injected with saline or lipopolysaccharide. Thereafter, vehicles, morphine, galantamine, and BAY-117082 were administered in different groups of animals. Subsequently, electroencephalography, enzyme-linked immunosorbent assay, western blot, and histopathological examinations were carried out and various indicators of inflammation and glutamate level were determined. Parallel analysis of Cxs, Panx-1, and EAAts in the brain was performed. Our findings strengthen the concept that unregulated expressions of Cxs, Panx-1, and EAATs contribute to glutamate accumulation and neuronal cell loss. Nuclear factor-kB (NF-κB) pathway can significantly contribute to glutamate homeostasis via modulating Cxs, Panx-1, and EAATs expressions. BAY-117082, via inhibition of IkK, promoted the anti-inflammatory effects of morphine as well as galantamine. We concluded that NF-κB is an important component of reshaping the expressions of Cxs, panx-1, and EAATs and the development of glutamate-induced neuronal degeneration.
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Affiliation(s)
- Shimaa Magdy
- Department of Physiology, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Maha Gamal
- Department of Physiology, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Nancy F Samir
- Department of Physiology, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Laila Rashed
- Department of Biochemistry, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Basma Emad Aboulhoda
- Department of Anatomy and Embryology, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Haitham S Mohammed
- Department of Biophysics, Faculty of Science, Cairo University, Giza, Egypt
| | - Nivin Sharawy
- Department of Physiology, Faculty of Medicine, Cairo University, Cairo, Egypt
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Busceti CL, Ginerete RP, Di Menna L, D'Errico G, Cisani F, Di Pietro P, Imbriglio T, Bruno V, Battaglia G, Fornai F, Monn JA, Pittaluga A, Nicoletti F. Behavioural and biochemical responses to methamphetamine are differentially regulated by mGlu2 and mGlu3 metabotropic glutamate receptors in male mice. Neuropharmacology 2021; 196:108692. [PMID: 34217776 DOI: 10.1016/j.neuropharm.2021.108692] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 06/04/2021] [Accepted: 06/27/2021] [Indexed: 01/09/2023]
Abstract
Group II metabotropic glutamate receptors (mGlu2 and mGlu3 receptors) shape mechanisms of methamphetamine addiction, but the individual role played by the two subtypes is unclear. We measured methamphetamine-induced conditioned place preference (CPP) and motor responses to single or repeated injections of methamphetamine in wild-type, mGlu2-/-, and mGlu3-/-mice. Only mGlu3-/-mice showed methamphetamine preference in the CPP test. Motor response to the first methamphetamine injection was dramatically reduced in mGlu2-/-mice, unless these mice were treated with the mGlu5 receptor antagonist, MTEP. In contrast, methamphetamine-induced sensitization was increased in mGlu3-/-mice compared to wild-type mice. Only mGlu3-/-mice sensitized to methamphetamine showed increases in phospho-ERK1/2 levels in the nucleus accumbens (NAc) and free radical formation in the NAc and medial prefrontal cortex. These changes were not detected in mGlu2-/-mice. We also measured a series of biochemical parameters related to the mechanism of action of methamphetamine in naïve mice to disclose the nature of the differential behavioural responses of the three genotypes. We found a reduced expression and activity of dopamine transporter (DAT) and vesicular monoamine transporter-2 in the NAc and striatum of mGlu2-/-and mGlu3-/-mice, whereas expression of the DAT adaptor, syntaxin 1A, was selectively increased in the striatum of mGlu3-/-mice. Methamphetamine-stimulated dopamine release in striatal slices was largely reduced in mGlu2-/-, but not in mGlu3-/-, mice. These findings suggest that drugs that selectively enhance mGlu3 receptor activity or negatively modulate mGlu2 receptors might be beneficial in the treatment of methamphetamine addiction and associated brain damage.
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Affiliation(s)
| | | | | | | | | | | | | | - Valeria Bruno
- IRCCS Neuromed, Pozzilli, Italy; Department of Physiology and Pharmacology, University Sapienza, Roma, Italy
| | - Giuseppe Battaglia
- IRCCS Neuromed, Pozzilli, Italy; Department of Physiology and Pharmacology, University Sapienza, Roma, Italy
| | - Francesco Fornai
- IRCCS Neuromed, Pozzilli, Italy; Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | | | - Anna Pittaluga
- Department of Pharmacy, University of Genova, Genova, Italy; IRCCS Ospedale Policlinico San Martino, Genova, Italy
| | - Ferdinando Nicoletti
- IRCCS Neuromed, Pozzilli, Italy; Department of Physiology and Pharmacology, University Sapienza, Roma, Italy.
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6
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Wan X, Ma B, Wang X, Guo C, Sun J, Cui J, Li L. S-Adenosylmethionine Alleviates Amyloid-β-Induced Neural Injury by Enhancing Trans-Sulfuration Pathway Activity in Astrocytes. J Alzheimers Dis 2021; 76:981-995. [PMID: 32597804 DOI: 10.3233/jad-200103] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
BACKGROUND Glutathione (GSH) is an important endogenous antioxidant protecting cells from oxidative injury. Cysteine (Cys), the substrate limiting the production of GSH, is mainly generated from the trans-sulfuration pathway. S-adenosylmethionine (SAM) is a critical molecule produced in the methionine cycle and can be utilized by the trans-sulfuration pathway. Reductions in GSH and SAM as well as dysfunction in the trans-sulfuration pathway have been documented in the brains of Alzheimer's disease (AD) patients. Our previous in vivo study revealed that SAM administration attenuated oxidative stress induced by amyloid-β (Aβ) through the enhancement of GSH. OBJECTIVE To investigate the effect of Aβ-induced oxidative stress on the trans-sulfuration pathway in astrocytes and neurons, respectively, and the protective effect of SAM on neurons. METHODS APP/PS1 transgenic mice and the primary cultured astrocytes, neurons, and HT22 cells were used in the current study. RESULTS SAM could rescue the low trans-sulfuration pathway activity induced by Aβ only in astrocytes, accompanying with increasing levels of Cys and GSH. The decrease of cellular viability of neurons caused by Aβ was greatly reversed when co-cultured with astrocytes with SAM intervention. Meanwhile, SAM improved cognitive performance in APP/PS1 mice. CONCLUSION In terms of astrocyte protection from oxidative stress, SAM might be a potent antioxidant in the therapy of AD patients.
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Affiliation(s)
- Xinkun Wan
- Department of Pathology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Bin Ma
- Department of Pathology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Xiaoxuan Wang
- Department of Pathology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Chenjia Guo
- Department of Pathology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Jing Sun
- Department of Pathology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Jing Cui
- Department of Pathology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Liang Li
- Department of Pathology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
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7
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Potential Benefits of N-Acetylcysteine in Preventing Pregabalin-Induced Seeking-Like Behavior. Healthcare (Basel) 2021; 9:healthcare9040376. [PMID: 33805329 PMCID: PMC8066267 DOI: 10.3390/healthcare9040376] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 03/13/2021] [Accepted: 03/18/2021] [Indexed: 11/24/2022] Open
Abstract
Substance-use disorder is globally prevalent and responsible for numerous social and medical problems. Pregabalin (Lyrica), typically used to treat diabetic neuropathy, has recently emerged as a drug of abuse. Drug abuse is associated with several neuronal changes, including the downregulation of glutamate transporters such as glutamate transporter 1 and cystine/glutamate antiporter. We investigated the effects of N-acetylcysteine, a glutamate transporter 1 and xCT upregulator, on pregabalin addiction using a conditioned place preference paradigm. Pregabalin (60 mg/kg) was found to induce conditioned place preference when compared to a vehicle. A 100 mg/kg dose of N-acetylcysteine was found to block pregabalin-seeking behaviors. These results support previous findings showing that glutamate transporters play an important role in pregabalin-induced seeking behaviors. N-acetylcysteine may represent a beneficial agent in preventing the abuse potential of pregabalin.
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8
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Fairweather SJ, Shah N, Brӧer S. Heteromeric Solute Carriers: Function, Structure, Pathology and Pharmacology. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 21:13-127. [PMID: 33052588 DOI: 10.1007/5584_2020_584] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Solute carriers form one of three major superfamilies of membrane transporters in humans, and include uniporters, exchangers and symporters. Following several decades of molecular characterisation, multiple solute carriers that form obligatory heteromers with unrelated subunits are emerging as a distinctive principle of membrane transporter assembly. Here we comprehensively review experimentally established heteromeric solute carriers: SLC3-SLC7 amino acid exchangers, SLC16 monocarboxylate/H+ symporters and basigin/embigin, SLC4A1 (AE1) and glycophorin A exchanger, SLC51 heteromer Ost α-Ost β uniporter, and SLC6 heteromeric symporters. The review covers the history of the heteromer discovery, transporter physiology, structure, disease associations and pharmacology - all with a focus on the heteromeric assembly. The cellular locations, requirements for complex formation, and the functional role of dimerization are extensively detailed, including analysis of the first complete heteromer structures, the SLC7-SLC3 family transporters LAT1-4F2hc, b0,+AT-rBAT and the SLC6 family heteromer B0AT1-ACE2. We present a systematic analysis of the structural and functional aspects of heteromeric solute carriers and conclude with common principles of their functional roles and structural architecture.
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Affiliation(s)
- Stephen J Fairweather
- Research School of Biology, Australian National University, Canberra, ACT, Australia. .,Resarch School of Chemistry, Australian National University, Canberra, ACT, Australia.
| | - Nishank Shah
- Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - Stefan Brӧer
- Research School of Biology, Australian National University, Canberra, ACT, Australia.
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9
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Sears SM, Hewett SJ. Influence of glutamate and GABA transport on brain excitatory/inhibitory balance. Exp Biol Med (Maywood) 2021; 246:1069-1083. [PMID: 33554649 DOI: 10.1177/1535370221989263] [Citation(s) in RCA: 76] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
An optimally functional brain requires both excitatory and inhibitory inputs that are regulated and balanced. A perturbation in the excitatory/inhibitory balance-as is the case in some neurological disorders/diseases (e.g. traumatic brain injury Alzheimer's disease, stroke, epilepsy and substance abuse) and disorders of development (e.g. schizophrenia, Rhett syndrome and autism spectrum disorder)-leads to dysfunctional signaling, which can result in impaired cognitive and motor function, if not frank neuronal injury. At the cellular level, transmission of glutamate and GABA, the principle excitatory and inhibitory neurotransmitters in the central nervous system control excitatory/inhibitory balance. Herein, we review the synthesis, release, and signaling of GABA and glutamate followed by a focused discussion on the importance of their transport systems to the maintenance of excitatory/inhibitory balance.
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Affiliation(s)
- Sheila Ms Sears
- Department of Biology, Program in Neuroscience, 2029Syracuse University, Syracuse, NY 13244, USA
| | - Sandra J Hewett
- Department of Biology, Program in Neuroscience, 2029Syracuse University, Syracuse, NY 13244, USA
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10
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Oxidative Stress and Neuroinflammation as a Pivot in Drug Abuse. A Focus on the Therapeutic Potential of Antioxidant and Anti-Inflammatory Agents and Biomolecules. Antioxidants (Basel) 2020; 9:antiox9090830. [PMID: 32899889 PMCID: PMC7555323 DOI: 10.3390/antiox9090830] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 09/01/2020] [Accepted: 09/03/2020] [Indexed: 12/11/2022] Open
Abstract
Drug abuse is a major global health and economic problem. However, there are no pharmacological treatments to effectively reduce the compulsive use of most drugs of abuse. Despite exerting different mechanisms of action, all drugs of abuse promote the activation of the brain reward system, with lasting neurobiological consequences that potentiate subsequent consumption. Recent evidence shows that the brain displays marked oxidative stress and neuroinflammation following chronic drug consumption. Brain oxidative stress and neuroinflammation disrupt glutamate homeostasis by impairing synaptic and extra-synaptic glutamate transport, reducing GLT-1, and system Xc− activities respectively, which increases glutamatergic neurotransmission. This effect consolidates the relapse-promoting effect of drug-related cues, thus sustaining drug craving and subsequent drug consumption. Recently, promising results as experimental treatments to reduce drug consumption and relapse have been shown by (i) antioxidant and anti-inflammatory synthetic molecules whose effects reach the brain; (ii) natural biomolecules secreted by mesenchymal stem cells that excel in antioxidant and anti-inflammatory properties, delivered via non-invasive intranasal administration to animal models of drug abuse and (iii) potent anti-inflammatory microRNAs and anti-miRNAs which target the microglia and reduce neuroinflammation and drug craving. In this review, we address the neurobiological consequences of brain oxidative stress and neuroinflammation that follow the chronic consumption of most drugs of abuse, and the current and potential therapeutic effects of antioxidants and anti-inflammatory agents and biomolecules to reduce these drug-induced alterations and to prevent relapse.
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11
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Cross AJ, Anthenelli R, Li X. Metabotropic Glutamate Receptors 2 and 3 as Targets for Treating Nicotine Addiction. Biol Psychiatry 2018; 83:947-954. [PMID: 29301614 PMCID: PMC5953779 DOI: 10.1016/j.biopsych.2017.11.021] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2017] [Revised: 11/02/2017] [Accepted: 11/14/2017] [Indexed: 12/27/2022]
Abstract
Tobacco smoking, driven by the addictive properties of nicotine, continues to be a worldwide health problem. Based on the well-established role of glutamatergic neurotransmission in drug addiction, novel medication development strategies seek to halt nicotine consumption and prevent relapse to tobacco smoking by modulating glutamate transmission. The presynaptic inhibitory metabotropic glutamate receptors 2 and 3 (mGluR2/3) are key autoreceptors on glutamatergic terminals that maintain glutamate homeostasis. Accumulating evidence suggests the critical role of mGluR2/3 in different aspects of nicotine addiction, including acquisition and maintenance of nicotine taking, nicotine withdrawal, and persistent nicotine seeking even after prolonged abstinence. The involvement of mGluR2/3 in other neuropsychiatric conditions, such as anxiety, depression, schizophrenia, Alzheimer's disease, Parkinson's disease, and pain, provides convincing evidence suggesting that mGluR2/3 may provide an effective therapeutic approach for comorbidity of smoking and these conditions. This focused review article highlights that mGluR2/3 provide a promising target in the search for smoking cessation medication with novel mechanisms of actions that differ from those of currently U.S. Food and Drug Administration-approved pharmacotherapies.
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Affiliation(s)
- Alan J Cross
- AstraZeneca Neuroscience Innovative Medicines, Cambridge, Massachusetts
| | - Robert Anthenelli
- Department of Psychiatry, School of Medicine, University of California San Diego, La Jolla, California
| | - Xia Li
- Department of Psychiatry, School of Medicine, University of California San Diego, La Jolla, California.
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12
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Kim R, Sepulveda-Orengo MT, Healey KL, Williams EA, Reissner KJ. Regulation of glutamate transporter 1 (GLT-1) gene expression by cocaine self-administration and withdrawal. Neuropharmacology 2018; 128:1-10. [PMID: 28919080 PMCID: PMC5714670 DOI: 10.1016/j.neuropharm.2017.09.019] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Revised: 09/06/2017] [Accepted: 09/11/2017] [Indexed: 12/24/2022]
Abstract
Downregulation of the astroglial glutamate transporter GLT-1 is observed in the nucleus accumbens (NAc) following administration of multiple drugs of abuse. The decrease in GLT-1 protein expression following cocaine self-administration is dependent on both the amount of cocaine self-administered and the length of withdrawal, with longer access to cocaine and longer withdrawal periods leading to greater decreases in GLT-1 protein. However, the mechanism(s) by which cocaine downregulates GLT-1 protein remains unknown. We used qRT-PCR to examine gene expression of GLT-1 splice isoforms (GLT-1A, GLT-1B) in the NAc, prelimbic cortex (PL) and basolateral amygdala (BLA) of rats, following two widely used models of cocaine self-administration: short-access (ShA) self-administration, and the long-access (LgA) self-administration/incubation model. While downregulation of GLT-1 protein is observed following ShA cocaine self-administration and extinction, this model did not lead to a change in GLT-1A or GLT-1B gene expression in any brain region examined. Forced abstinence following ShA cocaine self-administration also was without effect. In contrast, LgA cocaine self-administration and prolonged abstinence significantly decreased GLT-1A gene expression in the NAc and BLA, and significantly decreased GLT-1B gene expression in the PL. No change was observed in NAc GLT-1A gene expression one day after LgA cocaine self-administration, indicating withdrawal-induced decreases in GLT-1A mRNA. In addition, LgA cocaine self-administration and withdrawal induced hypermethylation of the GLT-1 gene in the NAc. These results indicate that a decrease in NAc GLT-1 mRNA is only observed after extended access to cocaine combined with protracted abstinence, and that epigenetic mechanisms likely contribute to this effect.
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Affiliation(s)
- Ronald Kim
- Department of Psychology and Neuroscience, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Marian T Sepulveda-Orengo
- Department of Psychology and Neuroscience, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Kati L Healey
- Department of Psychology and Neuroscience, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Emily A Williams
- Department of Psychology and Neuroscience, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Kathryn J Reissner
- Department of Psychology and Neuroscience, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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13
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Bachtell RK, Jones JD, Heinzerling KG, Beardsley PM, Comer SD. Glial and neuroinflammatory targets for treating substance use disorders. Drug Alcohol Depend 2017; 180:156-170. [PMID: 28892721 PMCID: PMC5790191 DOI: 10.1016/j.drugalcdep.2017.08.003] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 07/28/2017] [Accepted: 08/03/2017] [Indexed: 02/06/2023]
Abstract
BACKGROUND The plenary session at the 2016 Behavior, Biology and Chemistry: Translational Research in Addiction Conference focused on glia as potential players in the development, persistence and treatment of substance use disorders. Glia partake in various functions that are important for healthy brain activity. Drugs of abuse alter glial cell activity producing several perturbations in brain function that are thought to contribute to behavioral changes associated with substance use disorders. Consequently, drug-induced changes in glia-driven processes in the brain represent potential targets for pharmacotherapeutics treating substance use disorders. METHODS Four speakers presented preclinical and clinical research illustrating the effects that glial modulators have on abuse-related behavioral effects of psychostimulants and opioids. This review highlights some of these findings and expands its focus to include other research focused on drug-induced glia abnormalities and glia-focused treatment approaches in substance use disorders. RESULTS Preclinical findings show that drugs of abuse induce neuroinflammatory signals and disrupt glutamate homeostasis through their interaction with microglia and astrocytes. Preclinical and clinical studies testing the effects of glial modulators show general effectiveness in reducing behaviors associated with substance use disorders. CONCLUSIONS The contribution of drug-induced glial activity continues to emerge as an intriguing target for substance use disorder treatments. Clinical investigations of glial modulators have yielded promising results on substance use measures and indicate that they are generally safe and well-tolerated. However, results have not been entirely positive and more questions remain for continued exploration in the development and testing of glial-directed treatments for substance use disorders.
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Affiliation(s)
- Ryan K. Bachtell
- Department of Psychology and Neuroscience, and Center for Neuroscience, UCB 345, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Jermaine D. Jones
- Division on Substance Use Disorders, New York State Psychiatric Institute and College of Physicians and Surgeons, Columbia University, 1051 Riverside Drive, New York, NY 10032, USA
| | - Keith G. Heinzerling
- Department of Family Medicine and Center for Behavioral and Addiction Medicine, UCLA, Los Angeles, CA, USA
| | - Patrick M. Beardsley
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, 410 N. 12th Street, Richmond, VA 23298, USA
| | - Sandra D. Comer
- Division on Substance Use Disorders, New York State Psychiatric Institute and College of Physicians and Surgeons, Columbia University, 1051 Riverside Drive, New York, NY 10032, USA
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14
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Salatino JW, Ludwig KA, Kozai TDY, Purcell EK. Glial responses to implanted electrodes in the brain. Nat Biomed Eng 2017; 1:862-877. [PMID: 30505625 PMCID: PMC6261524 DOI: 10.1038/s41551-017-0154-1] [Citation(s) in RCA: 305] [Impact Index Per Article: 43.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 10/04/2017] [Indexed: 01/20/2023]
Abstract
The use of implants that can electrically stimulate or record electrophysiological or neurochemical activity in nervous tissue is rapidly expanding. Despite remarkable results in clinical studies and increasing market approvals, the mechanisms underlying the therapeutic effects of neuroprosthetic and neuromodulation devices, as well as their side effects and reasons for their failure, remain poorly understood. A major assumption has been that the signal-generating neurons are the only important target cells of neural-interface technologies. However, recent evidence indicates that the supporting glial cells remodel the structure and function of neuronal networks and are an effector of stimulation-based therapy. Here, we reframe the traditional view of glia as a passive barrier, and discuss their role as an active determinant of the outcomes of device implantation. We also discuss the implications that this has on the development of bioelectronic medical devices.
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Affiliation(s)
- Joseph W. Salatino
- Department of Biomedical Engineering, Michigan State University, East Lansing, MI, USA
- Institute for Quantitative Health Science and Engineering, Michigan State University, East Lansing, MI, USA
| | - Kip A. Ludwig
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, USA
| | - Takashi D. Y. Kozai
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
- Center for the Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, PA, USA
- McGowan Institute of Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Neurotech Center, University of Pittsburgh Brain Institute, Pittsburgh, PA, USA
| | - Erin K. Purcell
- Department of Biomedical Engineering, Michigan State University, East Lansing, MI, USA
- Institute for Quantitative Health Science and Engineering, Michigan State University, East Lansing, MI, USA
- Department of Electrical and Computer Engineering, Michigan State University, East Lansing, MI, USA
- Neuroscience Program, Michigan State University, East Lansing, MI, USA
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15
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Shin CB, Templeton TJ, Chiu AS, Kim J, Gable ES, Vieira PA, Kippin TE, Szumlinski KK. Endogenous glutamate within the prelimbic and infralimbic cortices regulates the incubation of cocaine-seeking in rats. Neuropharmacology 2017; 128:293-300. [PMID: 29061508 DOI: 10.1016/j.neuropharm.2017.10.024] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2017] [Revised: 10/05/2017] [Accepted: 10/19/2017] [Indexed: 12/30/2022]
Abstract
The incubation of cue-reinforced cocaine-seeking coincides with increased extracellular glutamate within the ventromedial prefrontal cortex (vmPFC). The vmPFC is comprised of two subregions that oppositely regulate drug-seeking, with infralimbic (IL) activity inhibiting, and prelimibic (PL) activity facilitating, drug-seeking. Thus, we hypothesized that increasing and decreasing endogenous glutamate within the IL would attenuate and potentiate, respectively, cue-reinforced drug-seeking behavior, with the converse effects observed upon manipulations of endogenous glutamate within the PL. Male Sprague-Dawley rats were trained to self-administer cocaine (0.25 mg/infusion; 6 h/day X 10 days), the delivery of which was signaled by a tone-light cue. Rats were then subdivided into 3 or 30 day withdrawal groups. For testing, rats were microinjected with vehicle, 20 mM of the mGlu2/3 agonist LY379268 (to lower endogenous glutamate), or 300 μM of the excitatory amino acid transporter inhibitor threo-β-benzyloxyaspartate (TBOA; to raise endogenous glutamate) into either the IL or PL (0.5 μl/side) and then given a 30-min test for cue-reinforced drug-seeking. Vehicle-infused rats exhibited incubated responding on the cocaine-associated lever. Neither LY379268 nor TBOA altered behavior at 3 days withdrawal, indicating that glutamate within neither subregion regulates cue-reinforced drug-seeking during early withdrawal. At 30 days withdrawal, intra-PL LY379268 microinjection significantly decreased drug-seeking behavior, while the effect was more modest when infused intra-IL. Interestingly, intra-IL TBOA attenuated incubated drug-seeking during protracted withdrawal, but did not affect behavior when infused intra-PL. These results argue that glutamate release within the PL in response to drug-seeking likely drives the manifestation of incubated cocaine-seeking during protracted withdrawal.
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Affiliation(s)
- Christina B Shin
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA 93106-9660, USA
| | - Taylor J Templeton
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA 93106-9660, USA
| | - Alvin S Chiu
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA 93106-9660, USA
| | - Jennifer Kim
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA 93106-9660, USA
| | - Ellen S Gable
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA 93106-9660, USA
| | - Philip A Vieira
- Center for Collaborative Biotechnology, University of California Santa Barbara, Santa Barbara, CA 93106-9660, USA
| | - Tod E Kippin
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA 93106-9660, USA; Department of Molecular, Cellular and Developmental Biology, Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, CA 93106-9660, USA; Center for Collaborative Biotechnology, University of California Santa Barbara, Santa Barbara, CA 93106-9660, USA
| | - Karen K Szumlinski
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA 93106-9660, USA; Department of Molecular, Cellular and Developmental Biology, Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, CA 93106-9660, USA.
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16
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Szumlinski KK, Lominac KD, Campbell RR, Cohen M, Fultz EK, Brown CN, Miller BW, Quadir SG, Martin D, Thompson AB, von Jonquieres G, Klugmann M, Phillips TJ, Kippin TE. Methamphetamine Addiction Vulnerability: The Glutamate, the Bad, and the Ugly. Biol Psychiatry 2017; 81:959-970. [PMID: 27890469 PMCID: PMC5391296 DOI: 10.1016/j.biopsych.2016.10.005] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 09/30/2016] [Accepted: 10/05/2016] [Indexed: 01/23/2023]
Abstract
BACKGROUND The high prevalence and severity of methamphetamine (MA) abuse demands greater neurobiological understanding of its etiology. METHODS We conducted immunoblotting and in vivo microdialysis procedures in MA high/low drinking mice, as well as in isogenic C57BL/6J mice that varied in their MA preference/taking, to examine the glutamate underpinnings of MA abuse vulnerability. Neuropharmacological and Homer2 knockdown approaches were also used in C57BL/6J mice to confirm the role for nucleus accumbens (NAC) glutamate/Homer2 expression in MA preference/aversion. RESULTS We identified a hyperglutamatergic state within the NAC as a biochemical trait corresponding with both genetic and idiopathic vulnerability for high MA preference and taking. We also confirmed that subchronic subtoxic MA experience elicits a hyperglutamatergic state within the NAC during protracted withdrawal, characterized by elevated metabotropic glutamate 1/5 receptor function and Homer2 receptor-scaffolding protein expression. A high MA-preferring phenotype was recapitulated by elevating endogenous glutamate within the NAC shell of mice and we reversed MA preference/taking by lowering endogenous glutamate and/or Homer2 expression within this subregion. CONCLUSIONS Our data point to an idiopathic, genetic, or drug-induced hyperglutamatergic state within the NAC as a mediator of MA addiction vulnerability.
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Affiliation(s)
- Karen K Szumlinski
- Department of Psychological and Brain Sciences, University of California at Santa Barbara, Santa Barbara, California; Molecular, Cellular and Developmental Biology, University of California at Santa Barbara, Santa Barbara, California.
| | - Kevin D Lominac
- Department of Psychological and Brain Sciences, University of California at Santa Barbara, Santa Barbara, California
| | - Rianne R Campbell
- Department of Psychological and Brain Sciences, University of California at Santa Barbara, Santa Barbara, California
| | - Matan Cohen
- Department of Psychological and Brain Sciences, University of California at Santa Barbara, Santa Barbara, California
| | - Elissa K Fultz
- Department of Psychological and Brain Sciences, University of California at Santa Barbara, Santa Barbara, California
| | - Chelsea N Brown
- Department of Psychological and Brain Sciences, University of California at Santa Barbara, Santa Barbara, California
| | - Bailey W Miller
- Department of Psychological and Brain Sciences, University of California at Santa Barbara, Santa Barbara, California
| | - Sema G Quadir
- Department of Psychological and Brain Sciences, University of California at Santa Barbara, Santa Barbara, California
| | - Douglas Martin
- Department of Psychological and Brain Sciences, University of California at Santa Barbara, Santa Barbara, California
| | - Andrew B Thompson
- Department of Psychological and Brain Sciences, University of California at Santa Barbara, Santa Barbara, California
| | - Georg von Jonquieres
- Translational Neuroscience Facility, School of Medical Sciences, University of New South Wales, New South Wales, Australia
| | - Matthias Klugmann
- Translational Neuroscience Facility, School of Medical Sciences, University of New South Wales, New South Wales, Australia
| | - Tamara J Phillips
- Behavioral Neuroscience and Methamphetamine Abuse Research Center, Oregon Health & Science University; VA Portland Health Care System, Portland, Oregon
| | - Tod E Kippin
- Department of Psychological and Brain Sciences, University of California at Santa Barbara, Santa Barbara, California; Molecular, Cellular and Developmental Biology, University of California at Santa Barbara, Santa Barbara, California; Neuroscience Research Institute, and Institute for Collaborative Biotechnology, University of California at Santa Barbara, Santa Barbara, California
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17
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Roberto M, Varodayan FP. Synaptic targets: Chronic alcohol actions. Neuropharmacology 2017; 122:85-99. [PMID: 28108359 DOI: 10.1016/j.neuropharm.2017.01.013] [Citation(s) in RCA: 106] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 12/23/2016] [Accepted: 01/14/2017] [Indexed: 01/02/2023]
Abstract
Alcohol acts on numerous cellular and molecular targets to regulate neuronal communication within the brain. Chronic alcohol exposure and acute withdrawal generate prominent neuroadaptations at synapses, including compensatory effects on the expression, localization and function of synaptic proteins, channels and receptors. The present article reviews the literature describing the synaptic effects of chronic alcohol exposure and their relevance for synaptic transmission in the central nervous system. This review is not meant to be comprehensive, but rather to highlight the effects that have been observed most consistently and that are thought to contribute to the development of alcohol dependence and the negative aspects of withdrawal. Specifically, we will focus on the major excitatory and inhibitory neurotransmitters in the brain, glutamate and GABA, respectively, and how their neuroadaptations after chronic alcohol exposure contributes to alcohol reinforcement, dependence and withdrawal. This article is part of the Special Issue entitled "Alcoholism".
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18
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Ze X, Su M, Zhao X, Jiang H, Hong J, Yu X, Liu D, Xu B, Sheng L, Zhou Q, Zhou J, Cui J, Li K, Wang L, Ze Y, Hong F. TiO2 nanoparticle-induced neurotoxicity may be involved in dysfunction of glutamate metabolism and its receptor expression in mice. ENVIRONMENTAL TOXICOLOGY 2016; 31:655-662. [PMID: 25411160 DOI: 10.1002/tox.22077] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2014] [Revised: 11/02/2014] [Accepted: 11/03/2014] [Indexed: 06/04/2023]
Abstract
Titanium dioxide nanoparticles (TiO2 NPs) have been used in environmental management, food, medicine, and industry. But TiO2 NPs have been demonstrated to cross the blood-brain barrier and store up in the brain organization, leading to glutamate-mediated neurotoxicity. However, the neurotoxicity in the brain is not well understood. In this study, mice were exposed to 1.25, 2.5, or 5 mg/kg body weight TiO2 NPs for 9 months, and the glutamate-glutamine cyclic pathway and expressions of glutamate receptors associated with the hippocampal neurotoxicity were investigated. Our findings showed elevations of glutamate release and phosphate-activated glutaminase activity, and reductions in glutamine and glutamine synthetase in the hippocampus following exposure to TiO2 NPs. Furthermore, TiO2 NPs significantly inhibited the expression of N-methyl-d-aspartate receptor subunits (including NR1, NR2A, and NR2B) and metabotropic glutamate receptor 2 in mouse hippocampus. These findings suggest that the imbalance of glutamate metabolism triggered inhibitions of glutamate receptor expression in the TiO2 NP-exposed hippocampus. © 2014 Wiley Periodicals, Inc. Environ Toxicol 31: 655-662, 2016.
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Affiliation(s)
- Xiao Ze
- Medical College of Soochow University, Suzhou, 215123, China
| | - Mingyu Su
- Suzhou Environmental Monitor Center, Suzhou, 215004, China
| | - Xiaoyang Zhao
- Medical College of Soochow University, Suzhou, 215123, China
| | - Hao Jiang
- Medical College of Soochow University, Suzhou, 215123, China
| | - Jie Hong
- Medical College of Soochow University, Suzhou, 215123, China
| | - Xiaohong Yu
- Medical College of Soochow University, Suzhou, 215123, China
| | - Dong Liu
- Medical College of Soochow University, Suzhou, 215123, China
| | - Bingqing Xu
- Medical College of Soochow University, Suzhou, 215123, China
| | - Lei Sheng
- Medical College of Soochow University, Suzhou, 215123, China
| | - Qiuping Zhou
- Medical College of Soochow University, Suzhou, 215123, China
| | - Junling Zhou
- Medical College of Soochow University, Suzhou, 215123, China
| | - Jingwen Cui
- Medical College of Soochow University, Suzhou, 215123, China
| | - Kai Li
- Medical College of Soochow University, Suzhou, 215123, China
| | - Ling Wang
- Library of Soochow University, Suzhou, 215021, China
| | - Yuguan Ze
- Medical College of Soochow University, Suzhou, 215123, China
| | - Fashui Hong
- Medical College of Soochow University, Suzhou, 215123, China
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19
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Kong L, Albano R, Madayag A, Raddatz N, Mantsch JR, Choi S, Lobner D, Baker DA. Pituitary Adenylate cyclase-activating polypeptide orchestrates neuronal regulation of the astrocytic glutamate-releasing mechanism system xc (.). J Neurochem 2016; 137:384-93. [PMID: 26851652 DOI: 10.1111/jnc.13566] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 01/28/2016] [Accepted: 02/01/2016] [Indexed: 12/26/2022]
Abstract
Glutamate signaling is achieved by an elaborate network involving neurons and astrocytes. Hence, it is critical to better understand how neurons and astrocytes interact to coordinate the cellular regulation of glutamate signaling. In these studies, we used rat cortical cell cultures to examine whether neurons or releasable neuronal factors were capable of regulating system xc (-) (Sxc), a glutamate-releasing mechanism that is expressed primarily by astrocytes and has been shown to regulate synaptic transmission. We found that astrocytes cultured with neurons or exposed to neuronal-conditioned media displayed significantly higher levels of Sxc activity. Next, we demonstrated that the pituitary adenylate cyclase-activating polypeptide (PACAP) may be a neuronal factor capable of regulating astrocytes. In support, we found that PACAP expression was restricted to neurons, and that PACAP receptors were expressed in astrocytes. Interestingly, blockade of PACAP receptors in cultures comprised of astrocytes and neurons significantly decreased Sxc activity to the level observed in purified astrocytes, whereas application of PACAP to purified astrocytes increased Sxc activity to the level observed in cultures comprised of neurons and astrocytes. Collectively, these data reveal that neurons coordinate the actions of glutamate-related mechanisms expressed by astrocytes, such as Sxc, a process that likely involves PACAP. A critical gap in modeling excitatory signaling is how distinct components of the glutamate system expressed by neurons and astrocytes are coordinated. In these studies, we found that system xc (-) (Sxc), a glutamate release mechanism expressed by astrocytes, is regulated by releasable neuronal factors including PACAP. This represents a novel form of neuron-astrocyte communication, and highlights the possibility that pathological changes involving astrocytic Sxc may stem from altered neuronal activity.
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Affiliation(s)
- Linghai Kong
- Department of Biomedical Sciences, Marquette University, Milwaukee, Wisconsin, USA
| | - Rebecca Albano
- Department of Biomedical Sciences, Marquette University, Milwaukee, Wisconsin, USA
| | - Aric Madayag
- Department of Biomedical Sciences, Marquette University, Milwaukee, Wisconsin, USA
| | - Nicholas Raddatz
- Department of Biomedical Sciences, Marquette University, Milwaukee, Wisconsin, USA
| | - John R Mantsch
- Department of Biomedical Sciences, Marquette University, Milwaukee, Wisconsin, USA
| | - SuJean Choi
- Department of Biomedical Sciences, Marquette University, Milwaukee, Wisconsin, USA
| | - Doug Lobner
- Department of Biomedical Sciences, Marquette University, Milwaukee, Wisconsin, USA
| | - David A Baker
- Department of Biomedical Sciences, Marquette University, Milwaukee, Wisconsin, USA
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20
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Lominac KD, Quadir SG, Barrett HM, McKenna CL, Schwartz LM, Ruiz PN, Wroten MG, Campbell RR, Miller BW, Holloway JJ, Travis KO, Rajasekar G, Maliniak D, Thompson AB, Urman LE, Kippin TE, Phillips TJ, Szumlinski KK. Prefrontal glutamate correlates of methamphetamine sensitization and preference. Eur J Neurosci 2016; 43:689-702. [PMID: 26742098 DOI: 10.1111/ejn.13159] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Revised: 12/16/2015] [Accepted: 12/17/2015] [Indexed: 12/28/2022]
Abstract
Methamphetamine (MA) is a widely misused, highly addictive psychostimulant that elicits pronounced deficits in neurocognitive function related to hypo-functioning of the prefrontal cortex (PFC). Our understanding of how repeated MA impacts excitatory glutamatergic transmission within the PFC is limited, as is information about the relationship between PFC glutamate and addiction vulnerability/resiliency. In vivo microdialysis and immunoblotting studies characterized the effects of MA (ten injections of 2 mg/kg, i.p.) upon extracellular glutamate in C57BL/6J mice and upon glutamate receptor and transporter expression, within the medial PFC. Glutamatergic correlates of both genetic and idiopathic variance in MA preference/intake were determined through studies of high vs. low MA-drinking selectively bred mouse lines (MAHDR vs. MALDR, respectively) and inbred C57BL/6J mice exhibiting spontaneously divergent place-conditioning phenotypes. Repeated MA sensitized drug-induced glutamate release and lowered indices of N-methyl-d-aspartate receptor expression in C57BL/6J mice, but did not alter basal extracellular glutamate content or total protein expression of Homer proteins, or metabotropic or α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid glutamate receptors. Elevated basal glutamate, blunted MA-induced glutamate release and ERK activation, as well as reduced protein expression of mGlu2/3 and Homer2a/b were all correlated biochemical traits of selection for high vs. low MA drinking, and Homer2a/b levels were inversely correlated with the motivational valence of MA in C57BL/6J mice. These data provide novel evidence that repeated, low-dose MA is sufficient to perturb pre- and post-synaptic aspects of glutamate transmission within the medial PFC and that glutamate anomalies within this region may contribute to both genetic and idiopathic variance in MA addiction vulnerability/resiliency.
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Affiliation(s)
- Kevin D Lominac
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, CA, 93106-9660, USA
| | - Sema G Quadir
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, CA, 93106-9660, USA
| | - Hannah M Barrett
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, CA, 93106-9660, USA
| | - Courtney L McKenna
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, CA, 93106-9660, USA
| | - Lisa M Schwartz
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, CA, 93106-9660, USA
| | - Paige N Ruiz
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, CA, 93106-9660, USA
| | - Melissa G Wroten
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, CA, 93106-9660, USA
| | - Rianne R Campbell
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, CA, 93106-9660, USA
| | - Bailey W Miller
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, CA, 93106-9660, USA
| | - John J Holloway
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, CA, 93106-9660, USA
| | - Katherine O Travis
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, CA, 93106-9660, USA
| | - Ganesh Rajasekar
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, CA, 93106-9660, USA
| | - Dan Maliniak
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, CA, 93106-9660, USA
| | - Andrew B Thompson
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, CA, 93106-9660, USA
| | - Lawrence E Urman
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, CA, 93106-9660, USA
| | - Tod E Kippin
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, CA, 93106-9660, USA
| | - Tamara J Phillips
- Behavioral Neuroscience and Methamphetamine Abuse Research Center, VA Portland Health Care System, Oregon Health & Science University, Portland, OR, 97239, USA
| | - Karen K Szumlinski
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, CA, 93106-9660, USA
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21
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Lewerenz J, Maher P. Chronic Glutamate Toxicity in Neurodegenerative Diseases-What is the Evidence? Front Neurosci 2015; 9:469. [PMID: 26733784 PMCID: PMC4679930 DOI: 10.3389/fnins.2015.00469] [Citation(s) in RCA: 468] [Impact Index Per Article: 52.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 11/24/2015] [Indexed: 12/13/2022] Open
Abstract
Together with aspartate, glutamate is the major excitatory neurotransmitter in the brain. Glutamate binds and activates both ligand-gated ion channels (ionotropic glutamate receptors) and a class of G-protein coupled receptors (metabotropic glutamate receptors). Although the intracellular glutamate concentration in the brain is in the millimolar range, the extracellular glutamate concentration is kept in the low micromolar range by the action of excitatory amino acid transporters that import glutamate and aspartate into astrocytes and neurons. Excess extracellular glutamate may lead to excitotoxicity in vitro and in vivo in acute insults like ischemic stroke via the overactivation of ionotropic glutamate receptors. In addition, chronic excitotoxicity has been hypothesized to play a role in numerous neurodegenerative diseases including amyotrophic lateral sclerosis, Alzheimer's disease and Huntington's disease. Based on this hypothesis, a good deal of effort has been devoted to develop and test drugs that either inhibit glutamate receptors or decrease extracellular glutamate. In this review, we provide an overview of the different pathways that are thought to lead to an over-activation of the glutamatergic system and glutamate toxicity in neurodegeneration. In addition, we summarize the available experimental evidence for glutamate toxicity in animal models of neurodegenerative diseases.
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Affiliation(s)
- Jan Lewerenz
- Department of Neurology, Ulm UniversityUlm, Germany
| | - Pamela Maher
- Cellular Neurobiology Laboratory, Salk Institute for Biological StudiesLa Jolla, CA, USA
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22
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Shi J, He Y, Hewett SJ, Hewett JA. Interleukin 1β Regulation of the System xc- Substrate-specific Subunit, xCT, in Primary Mouse Astrocytes Involves the RNA-binding Protein HuR. J Biol Chem 2015; 291:1643-1651. [PMID: 26601945 DOI: 10.1074/jbc.m115.697821] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2015] [Indexed: 01/05/2023] Open
Abstract
System xc(-) is a heteromeric amino acid cystine/glutamate antiporter that is constitutively expressed by cells of the CNS, where it functions in the maintenance of intracellular glutathione and extracellular glutamate levels. We recently determined that the cytokine, IL-1β, increases the activity of system xc(-) in CNS astrocytes secondary to an up-regulation of its substrate-specific light chain, xCT, and that this occurs, in part, at the level of transcription. However, an in silico analysis of the murine xCT 3'-UTR identified numerous copies of adenine- and uridine-rich elements, raising the possibility that undefined trans-acting factors governing mRNA stability and translation may also contribute to xCT expression. Here we show that IL-1β increases the level of mRNA encoding xCT in primary cultures of astrocytes isolated from mouse cortex in association with an increase in xCT mRNA half-life. Additionally, IL-1β induces HuR translocation from the nucleus to the cytoplasm. RNA immunoprecipitation analysis reveals that HuR binds directly to the 3'-UTR of xCT in an IL-1β-dependent manner. Knockdown of endogenous HuR protein abrogates the IL-1β-mediated increase in xCT mRNA half-life, whereas overexpression of HuR in unstimulated primary mouse astrocytes doubles the half-life of constitutive xCT mRNA. This latter effect is accompanied by an increase in xCT protein levels, as well as a functional increase in system xc(-) activity. Altogether, these data support a critical role for HuR in mediating the IL-1β-induced stabilization of astrocyte xCT mRNA.
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Affiliation(s)
- Jingxue Shi
- From the Department of Biology and Program in Neuroscience, Syracuse University, Syracuse, New York 13244
| | - Yan He
- From the Department of Biology and Program in Neuroscience, Syracuse University, Syracuse, New York 13244
| | - Sandra J Hewett
- From the Department of Biology and Program in Neuroscience, Syracuse University, Syracuse, New York 13244
| | - James A Hewett
- From the Department of Biology and Program in Neuroscience, Syracuse University, Syracuse, New York 13244.
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23
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Melendez RI, Roman C, Capo-Velez CM, Lasalde-Dominicci JA. Decreased glial and synaptic glutamate uptake in the striatum of HIV-1 gp120 transgenic mice. J Neurovirol 2015; 22:358-65. [PMID: 26567011 DOI: 10.1007/s13365-015-0403-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 10/27/2015] [Accepted: 10/30/2015] [Indexed: 12/22/2022]
Abstract
The mechanisms leading to the neurocognitive deficits in humans with immunodeficiency virus type 1 (HIV-1) are not well resolved. A number of cell culture models have demonstrated that the HIV-envelope glycoprotein 120 (gp120) decreases the reuptake of glutamate, which is necessary for learning, memory, and synaptic plasticity. However, the impact of brain HIV-1 gp120 on glutamate uptake systems in vivo remains unknown. Notably, alterations in brain glutamate uptake systems are implicated in a number of neurodegenerative and neurocognitive disorders. We characterized the kinetic properties of system XAG (sodium-dependent) and systems xc- (sodium-independent) [3H]-L-glutamate uptake in the striatum and hippocampus of HIV-1 gp120 transgenic mice, an established model of HIV neuropathology. We determined the kinetic constant Vmax (maximal velocity) and Km (affinity) of both systems XAG and xc- using subcellular preparations derived from neurons and glial cells. We show significant (30-35 %) reductions in the Vmax of systems XAG and xc- in both neuronal and glial preparations derived from the striatum, but not from the hippocampus of gp120 mice relative to wild-type (WT) controls. Moreover, immunoblot analysis showed that the protein expression of glutamate transporter subtype-1 (GLT-1), the predominant brain glutamate transporter, was significantly reduced in the striatum but not in the hippocampus of gp120 mice. These extensive and region-specific deficits of glutamate uptake likely contribute to the development and/or severity of HIV-associated neurocognitive disorders. Understanding the role of striatal glutamate uptake systems in HIV-1 gp120 may advance the development of new therapeutic strategies to prevent neuronal damage and improve cognitive function in HIV patients.
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Affiliation(s)
- Roberto I Melendez
- Department of Anatomy and Neurobiology, University of Puerto Rico, Medical Sciences Campus, Office #A-527, San Juan, 00936, Puerto Rico.
| | - Cristina Roman
- Department of Anatomy and Neurobiology, University of Puerto Rico, Medical Sciences Campus, Office #A-527, San Juan, 00936, Puerto Rico
| | - Coral M Capo-Velez
- Department of Biology, University of Puerto Rico, Rio Piedras, PR, 00936, USA
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Thorn TL, He Y, Jackman NA, Lobner D, Hewett JA, Hewett SJ. A Cytotoxic, Co-operative Interaction Between Energy Deprivation and Glutamate Release From System xc- Mediates Aglycemic Neuronal Cell Death. ASN Neuro 2015; 7:1759091415614301. [PMID: 26553727 PMCID: PMC4641554 DOI: 10.1177/1759091415614301] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The astrocyte cystine/glutamate antiporter (system xc(-)) contributes substantially to the excitotoxic neuronal cell death facilitated by glucose deprivation. The purpose of this study was to determine the mechanism by which this occurred. Using pure astrocyte cultures, as well as, mixed cortical cell cultures containing both neurons and astrocytes, we found that neither an enhancement in system xc(-) expression nor activity underlies the excitotoxic effects of aglycemia. In addition, using three separate bioassays, we demonstrate no change in the ability of glucose-deprived astrocytes--either cultured alone or with neurons--to remove glutamate from the extracellular space. Instead, we demonstrate that glucose-deprived cultures are 2 to 3 times more sensitive to the killing effects of glutamate or N-methyl-D-aspartate when compared with their glucose-containing controls. Hence, our results are consistent with the weak excitotoxic hypothesis such that a bioenergetic deficiency, which is measureable in our mixed but not astrocyte cultures, allows normally innocuous concentrations of glutamate to become excitotoxic. Adding to the burgeoning literature detailing the contribution of astrocytes to neuronal injury, we conclude that under our experimental paradigm, a cytotoxic, co-operative interaction between energy deprivation and glutamate release from astrocyte system xc(-) mediates aglycemic neuronal cell death.
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Affiliation(s)
- Trista L Thorn
- Department of Biology, Program in Neuroscience, Syracuse University, NY, USA Department of Neuroscience and Physiology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Yan He
- Department of Biology, Program in Neuroscience, Syracuse University, NY, USA
| | - Nicole A Jackman
- Department of Neuroscience, University of Connecticut Health Center, Farmington, CT, USA
| | - Doug Lobner
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI, USA
| | - James A Hewett
- Department of Biology, Program in Neuroscience, Syracuse University, NY, USA Department of Neuroscience and Physiology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Sandra J Hewett
- Department of Biology, Program in Neuroscience, Syracuse University, NY, USA Department of Neuroscience and Physiology, SUNY Upstate Medical University, Syracuse, NY, USA
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25
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Van Liefferinge J, Bentea E, Demuyser T, Albertini G, Follin-Arbelet V, Holmseth S, Merckx E, Sato H, Aerts JL, Smolders I, Arckens L, Danbolt NC, Massie A. Comparative analysis of antibodies to xCT (Slc7a11): Forewarned is forearmed. J Comp Neurol 2015; 524:1015-32. [DOI: 10.1002/cne.23889] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Revised: 08/24/2015] [Accepted: 08/25/2015] [Indexed: 12/21/2022]
Affiliation(s)
- Joeri Van Liefferinge
- Department of Pharmaceutical Chemistry and Drug Analysis, Center for Neurosciences; Vrije Universiteit Brussel; Brussels 1090 Belgium
| | - Eduard Bentea
- Department of Pharmaceutical Biotechnology and Molecular Biology, Center for Neurosciences; Vrije Universiteit Brussel; Brussels 1090 Belgium
| | - Thomas Demuyser
- Department of Pharmaceutical Chemistry and Drug Analysis, Center for Neurosciences; Vrije Universiteit Brussel; Brussels 1090 Belgium
| | - Giulia Albertini
- Department of Pharmaceutical Chemistry and Drug Analysis, Center for Neurosciences; Vrije Universiteit Brussel; Brussels 1090 Belgium
| | - Virginie Follin-Arbelet
- Department of Molecular Medicine, Institute of Basic Medical Sciences; University of Oslo; Oslo 0317 Norway
| | - Silvia Holmseth
- Department of Molecular Medicine, Institute of Basic Medical Sciences; University of Oslo; Oslo 0317 Norway
| | - Ellen Merckx
- Department of Pharmaceutical Biotechnology and Molecular Biology, Center for Neurosciences; Vrije Universiteit Brussel; Brussels 1090 Belgium
| | - Hideyo Sato
- Laboratory of Biochemistry and Molecular Biology, Department of Medical Technology; Niigata University; Niigata Niigata Prefecture 950-2181 Japan
| | - Joeri L. Aerts
- Laboratory of Molecular and Cellular Therapy, Department of Immunology-Physiology; Vrije Universiteit Brussel; Brussels 1090 Belgium
| | - Ilse Smolders
- Department of Pharmaceutical Chemistry and Drug Analysis, Center for Neurosciences; Vrije Universiteit Brussel; Brussels 1090 Belgium
| | - Lutgarde Arckens
- Laboratory of Neuroplasticity and Neuroproteomics; KU Leuven; Leuven 3000 Belgium
| | - Niels C. Danbolt
- Department of Molecular Medicine, Institute of Basic Medical Sciences; University of Oslo; Oslo 0317 Norway
| | - Ann Massie
- Department of Pharmaceutical Biotechnology and Molecular Biology, Center for Neurosciences; Vrije Universiteit Brussel; Brussels 1090 Belgium
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26
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Hwa LS, Nathanson AJ, Shimamoto A, Tayeh JK, Wilens AR, Holly EN, Newman EL, DeBold JF, Miczek KA. Aggression and increased glutamate in the mPFC during withdrawal from intermittent alcohol in outbred mice. Psychopharmacology (Berl) 2015; 232:2889-902. [PMID: 25899790 PMCID: PMC4515187 DOI: 10.1007/s00213-015-3925-y] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Accepted: 03/20/2015] [Indexed: 12/14/2022]
Abstract
RATIONALE Disrupted social behavior, including occasional aggressive outbursts, is characteristic of withdrawal from long-term alcohol (EtOH) use. Heavy EtOH use and exaggerated responses during withdrawal may be treated using glutamatergic N-methyl-D-aspartate receptor (NMDAR) antagonists. OBJECTIVES The current experiments explore aggression and medial prefrontal cortex (mPFC) glutamate as consequences of withdrawal from intermittent access to EtOH and changes in aggression and mPFC glutamate caused by NMDAR antagonists memantine and ketamine. METHODS Swiss male mice underwent withdrawal following 1-8 weeks of intermittent access to 20 % EtOH. Aggressive and nonaggressive behaviors with a conspecific were measured 6-8 h into EtOH withdrawal after memantine or ketamine (0-30 mg/kg, i.p.) administration. In separate mice, extracellular mPFC glutamate after memantine was measured during withdrawal using in vivo microdialysis. RESULTS At 6-8 h withdrawal from EtOH, mice exhibited more convulsions and aggression and decreased social contact compared to age-matched water controls. Memantine, but not ketamine, increased withdrawal aggression at the 5-mg/kg dose in mice with a history of 8 weeks of EtOH but not 1 or 4 weeks of EtOH or in water drinkers. Tonic mPFC glutamate was higher during withdrawal after 8 weeks of EtOH compared to 1 week of EtOH or 8 weeks of water. Five milligrams per kilogram of memantine increased glutamate in 8-week EtOH mice, but also in 1-week EtOH and water drinkers. CONCLUSIONS These studies reveal aggressive behavior as a novel symptom of EtOH withdrawal in outbred mice and confirm a role of NMDARs during withdrawal aggression and for disrupted social behavior.
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Affiliation(s)
- Lara S. Hwa
- Tufts University Department of Psychology, Medford, MA 02155
| | | | - Akiko Shimamoto
- Tufts University Department of Psychology, Medford, MA 02155
| | | | | | | | - Emily L. Newman
- Tufts University Department of Psychology, Medford, MA 02155
| | | | - Klaus A. Miczek
- Tufts University Department of Psychology, Medford, MA 02155
- Tufts University Department of Neuroscience, Boston, MA 02111
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27
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Cao F, Chen M, Li G, Ye K, Huang X, Zheng X. Altered expression of metabotropic glutamate receptor 1 alpha after acute diffuse brain injury: Effect of the competitive antagonist 1-aminoindan-1, 5-dicarboxylic acid. Neural Regen Res 2015; 7:119-24. [PMID: 25767486 PMCID: PMC4354126 DOI: 10.3969/j.issn.1673-5374.2012.02.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Accepted: 11/22/2011] [Indexed: 02/06/2023] Open
Abstract
The diffuse brain injury model was conducted in Sprague-Dawley rats, according to Marmarou's free-fall attack. The water content in brain tissue, expression of metabotropic glutamate receptor 1α mRNA and protein were significantly increased after injury, reached a peak at 24 hours, and then gradually decreased. After treatment with the competitive antagonist of metabotropic glutamate receptor 1α, (RS)-1-aminoindan-1, 5-dicarboxylic acid, the water content of brain tissues decreased between 12–72 hours after injury, and neurological behaviors improved at 2 weeks. These experimental findings suggest that the 1-aminoindan-1, 5-dicarboxylic acid may result in marked neuroprotection against diffuse brain injury.
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Affiliation(s)
- Fei Cao
- Department of Neurosurgery, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310003, Zhejiang Province, China ; Institute of Brain Medicine, Zhejiang University, Hangzhou 310003, Zhejiang Province, China
| | - Mantao Chen
- Department of Neurosurgery, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310003, Zhejiang Province, China ; Institute of Brain Medicine, Zhejiang University, Hangzhou 310003, Zhejiang Province, China
| | - Gu Li
- Department of Neurosurgery, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310003, Zhejiang Province, China ; Institute of Brain Medicine, Zhejiang University, Hangzhou 310003, Zhejiang Province, China
| | - Ke Ye
- Department of Neurosurgery, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310003, Zhejiang Province, China ; Institute of Brain Medicine, Zhejiang University, Hangzhou 310003, Zhejiang Province, China
| | - Xin Huang
- Department of Neurosurgery, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310003, Zhejiang Province, China ; Institute of Brain Medicine, Zhejiang University, Hangzhou 310003, Zhejiang Province, China
| | - Xiujue Zheng
- Department of Neurosurgery, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310003, Zhejiang Province, China ; Institute of Brain Medicine, Zhejiang University, Hangzhou 310003, Zhejiang Province, China
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28
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Reissner KJ, Gipson CD, Tran PK, Knackstedt LA, Scofield MD, Kalivas PW. Glutamate transporter GLT-1 mediates N-acetylcysteine inhibition of cocaine reinstatement. Addict Biol 2015; 20:316-23. [PMID: 24612076 DOI: 10.1111/adb.12127] [Citation(s) in RCA: 136] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Both pre-clinical and clinical studies indicate that N-acetylcysteine (NAC) may be useful in treating relapse to addictive drug use. Cocaine self-administration in rats reduces both cystine-glutamate exchange and glutamate transport via GLT-1 in the nucleus accumbens, and NAC treatment normalizes these two glial processes critical for maintaining glutamate homeostasis. However, it is not known if one or both of these actions by NAC is needed to inhibit relapse to cocaine seeking. To determine whether the restoration of GLT-1 and/or cystine-glutamate exchange is required for NAC to inhibit cue-induced reinstatement of cocaine seeking, we utilized the rat self-administration/extinction/reinstatement model of cocaine relapse. Rats were pre-treated in the nucleus accumbens with vivo-morpholino antisense oligomers targeting either GLT-1 or xCT (catalytic subunit of the cystine-glutamate exchanger) overlapping with daily NAC administration during extinction (100 mg/kg, i.p. for the last 5 days). Rats then underwent cue-induced reinstatement of active lever pressing in the absence of NAC, to determine if preventing NAC-induced restoration of one or the other protein was sufficient to block the capacity of chronic NAC to inhibit reinstatement. The vivo-morpholino suppression of xCT reduced cystine-glutamate exchange but did not affect NAC-induced reduction of reinstated cocaine seeking. In contrast, suppressing NAC-induced restoration of GLT-1 not only prevented NAC from inhibiting reinstatement, but augmented the capacity of cues to reinstate cocaine seeking. We hypothesized that the increased reinstatement after inhibiting NAC induction of GLT-1 resulted from increased extracellular glutamate, and show that augmented reinstatement is prevented by blocking mGluR5. Restoring GLT-1, not cystine-glutamate exchange, is a key mechanism whereby daily NAC reduces cue-induced cocaine reinstatement.
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Affiliation(s)
- Kathryn J. Reissner
- Department of Neurosciences; Medical University of South Carolina; Charleston SC USA
- Department of Psychology; University of North Carolina; Chapel Hill NC USA
| | - Cassandra D. Gipson
- Department of Neurosciences; Medical University of South Carolina; Charleston SC USA
| | - Phuong K. Tran
- Department of Neurosciences; Medical University of South Carolina; Charleston SC USA
| | | | - Michael D. Scofield
- Department of Neurosciences; Medical University of South Carolina; Charleston SC USA
| | - Peter W. Kalivas
- Department of Neurosciences; Medical University of South Carolina; Charleston SC USA
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29
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Lutgen V, Resch J, Qualmann K, Raddatz NJ, Panhans C, Olander EM, Kong L, Choi S, Mantsch JR, Baker DA. Behavioral assessment of acute inhibition of system xc (-) in rats. Psychopharmacology (Berl) 2014; 231:4637-47. [PMID: 24828877 PMCID: PMC4474164 DOI: 10.1007/s00213-014-3612-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Accepted: 05/01/2014] [Indexed: 12/20/2022]
Abstract
RATIONALE Gaps in our understanding of glutamatergic signaling may be key obstacles in accurately modeling complex CNS diseases. System xc (-) is an example of a poorly understood component of glutamate homeostasis that has the potential to contribute to CNS diseases. OBJECTIVES This study aims to determine whether system xc (-) contributes to behaviors used to model features of CNS disease states. METHODS In situ hybridization was used to map mRNA expression of xCT throughout the brain. Microdialysis in the prefrontal cortex was used to sample extracellular glutamate levels; HPLC was used to measure extracellular glutamate and tissue glutathione concentrations. Acute administration of sulfasalazine (8-16 mg/kg, IP) was used to decrease system xc (-) activity. Behavior was measured using attentional set shifting, elevated plus maze, open-field maze, Porsolt swim test, and social interaction paradigm. RESULTS The expression of xCT mRNA was detected throughout the brain, with high expression in several structures including the basolateral amygdala and prefrontal cortex. Doses of sulfasalazine that produced a reduction in extracellular glutamate levels were identified and subsequently used in the behavioral experiments. Sulfasalazine impaired performance in attentional set shifting and reduced the amount of time spent in an open arm of an elevated plus maze and the center of an open-field maze without altering behavior in a Porsolt swim test, total distance moved in an open-field maze, or social interaction. CONCLUSIONS The widespread distribution of system xc (-) and involvement in a growing list of behaviors suggests that this form of nonvesicular glutamate release is a key component of excitatory signaling.
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Affiliation(s)
- Victoria Lutgen
- Department of Biomedical Sciences, Marquette University, Suite 446, 561 N. 15 St, Milwaukee, WI 53233
| | - Jon Resch
- Department of Biomedical Sciences, Marquette University, Suite 446, 561 N. 15 St, Milwaukee, WI 53233
| | - Krista Qualmann
- Department of Biomedical Sciences, Marquette University, Suite 446, 561 N. 15 St, Milwaukee, WI 53233
| | - Nicholas J. Raddatz
- Department of Biomedical Sciences, Marquette University, Suite 446, 561 N. 15 St, Milwaukee, WI 53233
| | - Cristina Panhans
- Department of Biomedical Sciences, Marquette University, Suite 446, 561 N. 15 St, Milwaukee, WI 53233
| | - Ellen M. Olander
- Department of Biomedical Sciences, Marquette University, Suite 446, 561 N. 15 St, Milwaukee, WI 53233
| | - Linghai Kong
- Department of Biomedical Sciences, Marquette University, Suite 446, 561 N. 15 St, Milwaukee, WI 53233
| | - SuJean Choi
- Department of Biomedical Sciences, Marquette University, Suite 446, 561 N. 15 St, Milwaukee, WI 53233
| | - John R. Mantsch
- Department of Biomedical Sciences, Marquette University, Suite 446, 561 N. 15 St, Milwaukee, WI 53233
| | - David A. Baker
- Department of Biomedical Sciences, Marquette University, Suite 446, 561 N. 15 St, Milwaukee, WI 53233
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30
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Pomierny-Chamiolo L, Miszkiel J, Frankowska M, Pomierny B, Niedzielska E, Smaga I, Fumagalli F, Filip M. Withdrawal from cocaine self-administration and yoked cocaine delivery dysregulates glutamatergic mGlu5 and NMDA receptors in the rat brain. Neurotox Res 2014; 27:246-58. [PMID: 25408547 PMCID: PMC4353866 DOI: 10.1007/s12640-014-9502-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Revised: 10/06/2014] [Accepted: 11/06/2014] [Indexed: 12/16/2022]
Abstract
In human addicts and in animal models, chronic cocaine use leads to numerous alterations in glutamatergic transmission, including its receptors. The present study focused on metabotropic glutamatergic receptors type 5 (mGluR5) and N-methyl-D-aspartate receptor subunits (NMDAR: GluN1, GluN2A, GluN2B) proteins during cocaine self-administration and after 10-day of extinction training in rats. To discriminate the contingent from the non-contingent cocaine delivery, we employed the “yoked”-triad control procedure. Protein expression in rat prefrontal cortex, nucleus accumbens, hippocampus, and dorsal striatum was determined. We also examined the Homer1b/c protein, a member of the postsynaptic density protein family that links NMDAR to mGluR5. Our results revealed that cocaine self-administration selectively increased GluN1 and GluN2A subunit in the rat hippocampus and dorsal striatum, respectively, while mGluR5 protein expression was similarly increased in the dorsal striatum of both experimental groups. Withdrawal from both contingent and non-contingent cocaine delivery induced parallel increases in prefrontal cortical GluN2A protein expression, hippocampal mGluR5, and GluN1 protein expression as well as in accumbal GluN1 subunit expression, while the mGluR5 expression was reduced in the prefrontal cortex. Extinction training in animals with a history of cocaine self-administration resulted in an elevation of the hippocampal GluN2A/GluN2B subunits and accumbal mGluR5, and in a 50 % decrease of mGluR5 protein expression in the dorsal striatum. The latter reduction was associated with Homer1b/1c protein level decrease. Our results showed that both contingent and non-contingent cocaine administration produces numerous, brain region specific, alterations in the mGluR5, NMDA, and Homer1b/1c protein expression which are dependent on the modality of cocaine administration.
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Affiliation(s)
- Lucyna Pomierny-Chamiolo
- Department of Toxicology, Department of Biochemical Toxicology, Faculty of Pharmacy, Jagiellonian University, Medical College, Medyczna 9, 30-688, Kraków, Poland,
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31
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Pollard M, Bartolome JM, Conn PJ, Steckler T, Shaban H. Modulation of neuronal microcircuit activities within the medial prefrontal cortex by mGluR5 positive allosteric modulator. J Psychopharmacol 2014; 28:935-46. [PMID: 25031220 PMCID: PMC4356529 DOI: 10.1177/0269881114542856] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Suppressing anxiety and fear memory relies on bidirectional projections between the medial prefrontal cortex and the amygdala. Positive allosteric modulators of mGluR5 improve cognition in animal models of schizophrenia and retrieval of newly formed associations such as extinction of fear-conditioned behaviour. The increase in neuronal network activities of the medial prefrontal cortex is influenced by both mGluR1 and mGluR5; however, it is not well understood how they modulate network activities and downstream information processing. To map mGluR5-mediated network activity in relation to its emergence as a viable cognitive enhancer, we tested group I mGluR compounds on medial prefrontal cortex network activity via multi-electrode array neuronal spiking and whole-cell patch clamp recordings. Results indicate that mGluR5 activation promotes feed-forward inhibition that depends on recruitment of neuronal activity by carbachol-evoked up states. The rate of neuronal spiking activity under the influence of carbachol was reduced by the mGluR5 positive allosteric modulator, N-(1,3-Diphenyl-1H-pyrazolo-5-yl)-4-nitrobenzamide (VU-29), and enhanced by the mGluR5 negative allosteric modulator, 3-((2-methyl-1,3-thiazol-4-yl)ethynyl)pyridine hydrochloride (MTEP). Spontaneous inhibitory post-synaptic currents were increased upon application of carbachol and in combination with VU-29. These results emphasize a bias towards tonic mGluR5-mediated inhibition that might serve as a signal-to-noise enhancer of sensory inputs projected from associated limbic areas onto the medial prefrontal cortex neuronal microcircuit.
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Affiliation(s)
| | | | - P Jeffrey Conn
- Department of Pharmacology, and the Vanderbilt Center for Neuroscience Drug Discovery 2, Vanderbilt University Medical School, Nashville, TN, USA
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32
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Ohi Y, Kimura S, Haji A. Modulation of glutamatergic transmission by metabotropic glutamate receptor activation in second-order neurons of the guinea pig nucleus tractus solitarius. Brain Res 2014; 1581:12-22. [DOI: 10.1016/j.brainres.2014.04.031] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 04/10/2014] [Accepted: 04/23/2014] [Indexed: 11/30/2022]
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33
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Soria FN, Pérez-Samartín A, Martin A, Gona KB, Llop J, Szczupak B, Chara JC, Matute C, Domercq M. Extrasynaptic glutamate release through cystine/glutamate antiporter contributes to ischemic damage. J Clin Invest 2014; 124:3645-55. [PMID: 25036707 DOI: 10.1172/jci71886] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Accepted: 05/21/2014] [Indexed: 01/21/2023] Open
Abstract
During brain ischemia, an excessive release of glutamate triggers neuronal death through the overactivation of NMDA receptors (NMDARs); however, the underlying pathways that alter glutamate homeostasis and whether synaptic or extrasynaptic sites are responsible for excess glutamate remain controversial. Here, we monitored ischemia-gated currents in pyramidal cortical neurons in brain slices from rodents in response to oxygen and glucose deprivation (OGD) as a real-time glutamate sensor to identify the source of glutamate release and determined the extent of neuronal damage. Blockade of excitatory amino acid transporters or vesicular glutamate release did not inhibit ischemia-gated currents or neuronal damage after OGD. In contrast, pharmacological inhibition of the cystine/glutamate antiporter dramatically attenuated ischemia-gated currents and cell death after OGD. Compared with control animals, mice lacking a functional cystine/glutamate antiporter exhibited reduced anoxic depolarization and neuronal death in response to OGD. Furthermore, glutamate released by the cystine/glutamate antiporter activated extrasynaptic, but not synaptic, NMDARs, and blockade of extrasynaptic NMDARs reduced ischemia-gated currents and cell damage after OGD. Finally, PET imaging showed increased cystine/glutamate antiporter function in ischemic rats. Altogether, these data suggest that cystine/glutamate antiporter function is increased in ischemia, contributing to elevated extracellular glutamate concentration, overactivation of extrasynaptic NMDARs, and ischemic neuronal death.
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34
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Metabotropic glutamate receptors regulate cortical gamma hyperactivities elicited by ketamine in rats. Neurosci Lett 2014; 567:30-4. [DOI: 10.1016/j.neulet.2014.03.025] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 03/12/2014] [Accepted: 03/15/2014] [Indexed: 12/11/2022]
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35
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Dysregulation of dopamine and glutamate release in the prefrontal cortex and nucleus accumbens following methamphetamine self-administration and during reinstatement in rats. Neuropsychopharmacology 2014; 39:811-22. [PMID: 23995583 PMCID: PMC3924513 DOI: 10.1038/npp.2013.231] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Revised: 08/08/2013] [Accepted: 08/27/2013] [Indexed: 01/14/2023]
Abstract
Methamphetamine (meth) addicts often exhibit enduring cognitive and neural deficits that likely contribute to persistent drug seeking and the high rates of relapse. These deficits may be related to changes in the prefrontal cortex (PFC) and its glutamatergic projections to the nucleus accumbens (NAc). Here, we performed in vivo microdialysis in the PFC and NAc in rats following either meth self-administration or yoked-saline control histories to assess baseline glutamate (GLU) levels, or reinstatement-evoked GLU and dopamine (DA) efflux in both regions simultaneously under cue-induced, meth-primed, or combined cues+meth reinstatement conditions. Our results show that meth self-administration (1) reduced basal GLU levels in both the dmPFC and NAc, (2) concurrently increased dmPFC and NAc GLU efflux during reinstatement, and (3) increased DA efflux in the dmPFC, but not in the NAc, under all reinstatement conditions when compared with yoked-saline controls. These data demonstrate for the first time that a history of psychostimulant self-administration alters GLU homeostasis not only in the NAc, but also in the dmPFC, its primary GLU projection source. Furthermore, combined cues+meth-primed reinstatement conditions produced the most pronounced increases in mPFC and NAc extracellular GLU, suggesting that the cue and meth prime conditions are additive in promoting reinstatement. Finally, increased efflux of DA in the dmPFC, but not in the NAc, across reinstatement conditions suggests that DA release in the dmPFC may be an important mediator of drug seeking initiated by multiple relapse triggers.
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36
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Behavioral characterization of system xc- mutant mice. Behav Brain Res 2014; 265:1-11. [PMID: 24548853 DOI: 10.1016/j.bbr.2014.02.010] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Revised: 02/04/2014] [Accepted: 02/08/2014] [Indexed: 01/18/2023]
Abstract
The slc7a11 gene encodes xCT, an essential component of 'system xc-', a plasma membrane exchanger that imports cystine and exports glutamate. Slc7a11 is expressed primarily in the brain, but its role there is not clear. We performed behavioral tests on two different strains of homozygous slc7a11 mutant mice ('sut' and 'xCT'), as well as heteroallelic offspring of these two strains ('xCT/sut') and their associated genetic backgrounds. Homozygous sut mutant males showed reduced spontaneous alternation in spontaneous alternation tasks as well as reduced movement in an open field maze, but xCT and xCT/sut strains did not show significant changes in these tasks compared to appropriate controls. Neither xCT nor sut mutants showed differences from controls in rotarod tests. Female behavioral phenotypes were independent of estrus cycle stage. To ensure that homozygous xCT, sut, and xCT/sut strains all represent protein null alleles, we measured whole brain xCT protein levels using immunoblots. xCT, sut and xCT/sut strains showed no detectable xCT protein expression, confirming them as null alleles. Previously published microdialysis experiments showed reduced striatal glutamate in xCT mutants. Using the same methods, we measured reduced interstitial glutamate levels in the striatum but not cerebellum of sut mutants. However, we detected no glutamate change in the striatum or cerebellum of sut/xCT mice. We detected no changes in whole brain EAAT-1, -2, or -3 expression. We conclude that the behavioral and chemical differences exist between slc7a11 mutant strains, but we were unable to definitively attribute any of these differences to loss of system xc-.
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37
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Mahler SV, Hensley-Simon M, Tahsili-Fahadan P, LaLumiere RT, Thomas C, Fallon RV, Kalivas PW, Aston-Jones G. Modafinil attenuates reinstatement of cocaine seeking: role for cystine-glutamate exchange and metabotropic glutamate receptors. Addict Biol 2014; 19:49-60. [PMID: 23017017 DOI: 10.1111/j.1369-1600.2012.00506.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Modafinil may be useful for treating stimulant abuse, but the mechanisms by which it acts to do so are unknown. Indeed, a primary effect of modafinil is to inhibit dopamine transport, which typically promotes rather than inhibits motivated behavior. Therefore, we examined the role of nucleus accumbens extracellular glutamate and the group II metabotropic glutamate receptor (mGluR2/3) in modafinil effects. One group of rats was trained to self-administer cocaine for 10 days and extinguished, then given priming injections of cocaine to elicit reinstatement. Modafinil (300 mg/kg, intraperitoneal) inhibited reinstated cocaine seeking (but did not alter extinction responding by itself), and this effect was prevented by pre-treatment with bilateral microinjections of the mGluR2/3 antagonist LY-341495 (LY) into nucleus accumbens core. No reversal of modafinil effects was seen after unilateral accumbens core LY, or bilateral LY in the rostral pole of accumbens. Next, we sought to explore effects of modafinil on extracellular glutamate levels in accumbens after chronic cocaine. Separate rats were administered non-contingent cocaine, and after 3 weeks of withdrawal underwent accumbens microdialysis. Modafinil increased extracellular accumbens glutamate in chronic cocaine, but not chronic saline-pre-treated animals. This increase was prevented by reverse dialysis of cystine-glutamate exchange or voltage-dependent calcium channel antagonists. Voltage-dependent sodium channel blockade partly attenuated the increase in glutamate, but mGluR1 blockade did not. We conclude that modafinil increases extracellular glutamate in nucleus accumbens from glial and neuronal sources in cocaine-exposed rats, which may be important for its mGluR2/3-mediated antirelapse properties.
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Affiliation(s)
- Stephen V. Mahler
- Department of Neurosciences; Medical University of South Carolina; Charleston SC USA
| | - Megan Hensley-Simon
- Department of Neurosciences; Medical University of South Carolina; Charleston SC USA
| | - Pouya Tahsili-Fahadan
- Department of Neurosciences; Medical University of South Carolina; Charleston SC USA
| | - Ryan T. LaLumiere
- Department of Neurosciences; Medical University of South Carolina; Charleston SC USA
| | - Charles Thomas
- Department of Neurosciences; Medical University of South Carolina; Charleston SC USA
| | - Rebecca V. Fallon
- Department of Neurosciences; Medical University of South Carolina; Charleston SC USA
| | - Peter W. Kalivas
- Department of Neurosciences; Medical University of South Carolina; Charleston SC USA
| | - Gary Aston-Jones
- Department of Neurosciences; Medical University of South Carolina; Charleston SC USA
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The SLC3 and SLC7 families of amino acid transporters. Mol Aspects Med 2013; 34:139-58. [PMID: 23506863 DOI: 10.1016/j.mam.2012.10.007] [Citation(s) in RCA: 471] [Impact Index Per Article: 42.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Accepted: 08/15/2012] [Indexed: 01/18/2023]
Abstract
Amino acids are necessary for all living cells and organisms. Specialized transporters mediate the transfer of amino acids across plasma membranes. Malfunction of these proteins can affect whole-body homoeostasis giving raise to diverse human diseases. Here, we review the main features of the SLC3 and SLC7 families of amino acid transporters. The SLC7 family is divided into two subfamilies, the cationic amino acid transporters (CATs), and the L-type amino acid transporters (LATs). The latter are the light or catalytic subunits of the heteromeric amino acid transporters (HATs), which are associated by a disulfide bridge with the heavy subunits 4F2hc or rBAT. These two subunits are glycoproteins and form the SLC3 family. Most CAT subfamily members were functionally characterized and shown to function as facilitated diffusers mediating the entry and efflux of cationic amino acids. In certain cells, CATs play an important role in the delivery of L-arginine for the synthesis of nitric oxide. HATs are mostly exchangers with a broad spectrum of substrates and are crucial in renal and intestinal re-absorption and cell redox balance. Furthermore, the role of the HAT 4F2hc/LAT1 in tumor growth and the application of LAT1 inhibitors and PET tracers for reduction of tumor progression and imaging of tumors are discussed. Finally, we describe the link between specific mutations in HATs and the primary inherited aminoacidurias, cystinuria and lysinuric protein intolerance.
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Timmer KM, Steketee JD. Group I metabotropic glutamate receptors in the medial prefrontal cortex: role in mesocorticolimbic glutamate release in cocaine sensitization. Synapse 2013; 67:887-96. [PMID: 23913407 DOI: 10.1002/syn.21699] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Revised: 07/02/2013] [Accepted: 07/12/2013] [Indexed: 11/08/2022]
Abstract
Cocaine sensitization is associated with increased excitability of pyramidal projection neurons in the medial prefrontal cortex. Such hyperexcitability is presumed to increase glutamatergic input to the nucleus accumbens and ventral tegmental area. This study examined the effects of medial prefrontal cortex Group I metabotropic glutamate receptor activation on glutamate levels in the medial prefrontal cortex, nucleus accumbens, and ventral tegmental area in sensitized and control animals. Male Sprague-Dawley rats received four daily injections of cocaine (15 mg/kg, i.p.) or saline (1 mL/kg i.p.). One, 7, or 21 days from the fourth injection, dual-probe microdialysis experiments were performed wherein Group I metabotropic glutamate receptor agonist DHPG was infused into the medial prefrontal cortex and glutamate levels in this region as well as the nucleus accumbens or ventral tegmental area were examined. Intra-mPFC DHPG infusion increased glutamate levels in the medial prefrontal cortex at 1 and 7 days withdrawal, and in the nucleus accumbens at 21 days withdrawal in sensitized rats. These results suggest Group I metabotropic glutamate receptor activation may contribute to the increased excitability of medial prefrontal cortex pyramidal neurons in sensitized animals.
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Affiliation(s)
- Kristin M Timmer
- Department of Pharmacology, University of Tennessee Health Science Center, Memphis, Tennessee, 38163
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40
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Imbalances in prefrontal cortex CC-Homer1 versus CC-Homer2 expression promote cocaine preference. J Neurosci 2013; 33:8101-13. [PMID: 23658151 DOI: 10.1523/jneurosci.1727-12.2013] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Homer postsynaptic scaffolding proteins regulate forebrain glutamate transmission and thus, are likely molecular candidates mediating hypofrontality in addiction. Protracted withdrawal from cocaine experience increases the relative expression of Homer2 versus Homer1 isoforms within medial prefrontal cortex (mPFC). Thus, this study used virus-mediated gene transfer strategies to investigate the functional relevance of an imbalance in mPFC Homer1/2 expression as it relates to various measures of sensorimotor, cognitive, emotional and motivational processing, as well as accompanying alterations in extracellular glutamate in C57BL/6J mice. mPFC Homer2b overexpression elevated basal glutamate content and blunted cocaine-induced glutamate release within the mPFC, whereas Homer2b knockdown produced the opposite effects. Despite altering mPFC glutamate, Homer2b knockdown failed to influence cocaine-elicited conditioned place preferences, nor did it produce consistent effects on any other behavioral measures. In contrast, elevating the relative expression of Homer2b versus Homer1 within mPFC, by overexpressing Homer2b or knocking down Homer1c, shifted the dose-response function for cocaine-conditioned reward to the left, without affecting cocaine locomotion or sensitization. Intriguingly, both these transgenic manipulations produced glutamate anomalies within the nucleus accumbens (NAC) of cocaine-naive animals that are reminiscent of those observed in cocaine experienced animals, including reduced basal extracellular glutamate content, reduced Homer1/2 and glutamate receptor expression, and augmented cocaine-elicited glutamate release. Together, these data provide novel evidence in support of opposing roles for constitutively expressed Homer1 and Homer2 isoforms in regulating mPFC glutamate transmission in vivo and support the hypothesis that cocaine-elicited increases in the relative amount of mPFC Homer2 versus Homer1 signaling produces abnormalities in NAC glutamate transmission that enhance vulnerability to cocaine reward.
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Prefrontal cortical kappa-opioid receptor modulation of local neurotransmission and conditioned place aversion. Neuropsychopharmacology 2013; 38:1770-9. [PMID: 23542927 PMCID: PMC3717537 DOI: 10.1038/npp.2013.76] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Revised: 03/06/2013] [Accepted: 03/21/2013] [Indexed: 01/09/2023]
Abstract
Kappa-opioid receptors (KORs) are important for motivation and other medial prefrontal cortex (mPFC)-dependent behaviors. Although KORs are present in the mPFC, their role in regulating transmission in this brain region and their contribution to KOR-mediated aversion are not known. Using in vivo microdialysis in rats and mice, we demonstrate that intra-mPFC administration of the selective KOR agonist U69,593 decreased local dopamine (DA) overflow, while reverse dialysis of the KOR antagonist nor-Binaltorphimine (nor-BNI) enhanced mPFC DA overflow. Extracellular amino-acid levels were also affected by KORs, as U69,593 reduced glutamate and GABA levels driven by the glutamate reuptake blocker, l-trans-pyrrolidine-2,4-dicarboxylate. Whole-cell recordings from mPFC layer V pyramidal neurons revealed that U69,593 decreased the frequency, but not amplitude, of glutamatergic mini EPSPs. To determine whether KOR regulation of mPFC DA overflow was mediated by KOR on DA terminals, we utilized a Cre recombinase-driven mouse line lacking KOR in DA neurons. In these mice, basal DA release or uptake was unaltered relative to controls, but attenuation of mPFC DA overflow by local U69,593 was not observed, indicating KOR acts directly on mPFC DA terminals to locally inhibit DA levels. Conditioning procedures were then used to determine whether mPFC KOR signaling was necessary for KOR-mediated aversion. U69,593-mediated conditioned place aversion was blocked by intra-mPFC nor-BNI microinjection. These findings demonstrate that mPFC KORs negatively regulate DA and amino-acid neurotransmission, and are necessary for KOR-mediated aversion.
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Hikichi H, Kaku A, Karasawa JI, Chaki S. Stimulation of metabotropic glutamate (mGlu) 2 receptor and blockade of mGlu1 receptor improve social memory impairment elicited by MK-801 in rats. J Pharmacol Sci 2013; 122:10-6. [PMID: 23603933 DOI: 10.1254/jphs.13036fp] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
Glutamatergic dysfunction has been implicated in psychiatric disorders such as schizophrenia. Both the stimulation of the metabotropic glutamate (mGlu) 2/3 receptor and the blockade of the mGlu1 receptor have been shown to be effective in a number of animal models of schizophrenia. However, the efficacy for social cognition, which is poorly managed by current medication, has not been fully addressed. The present study evaluated the effects of an mGlu2/3-receptor agonist and an mGlu1-receptor antagonist on social memory impairment in rats. Pretreatment with an mGlu2/3-receptor agonist, (-)-2-oxa-4-aminobicyclo[3.1.0]hexane-4,6-dicarboxylate (LY379268), or an mGlu1-receptor antagonist, (3,4-dihydro-2H-pyrano[2,3-b]quinolin-7-yl)-(cis-4-methoxycyclohexyl)-methanone (JNJ16259685), improved social memory impairment induced by 5R,10S-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine hydrogen maleate (MK-801) without affecting the social interactions. In addition, the intraperitoneal administration of an mGlu2-receptor potentiator, 3'-[[(2-cyclopentyl-2,3-dihydro-6,7-dimethyl-1-oxo-1H-inden-5-yl)oxy]methyl]-[1,1'-biphenyl]-4-carboxylic acid (BINA), also improved the MK-801-induced impairment of social memory, which was blocked by pretreatment with an mGlu2/3-receptor antagonist, (2S)-2-amino-2-[(1S,2S)-2-carboxycycloprop-1-yl]-3-(xanth-9-yl) propanoic acid (LY341495). These findings indicate that both the stimulation of the mGlu2 receptor and the inhibition of an mGlu1 receptor improve social memory impairment elicited by MK-801, and both manipulations could be effective approaches for the treatment of certain cognitive dysfunctions observed in schizophrenic patients.
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Affiliation(s)
- Hirohiko Hikichi
- Discovery Pharmacology I, Molecular Function and Pharmacology Laboratories, Taisho Pharmaceutical Co., Ltd., Japan
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43
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Ben-Shahar O, Sacramento AD, Miller BW, Webb SM, Wroten MG, Silva HE, Caruana AL, Gordon EJ, Ploense KL, Ditzhazy J, Kippin TE, Szumlinski KK. Deficits in ventromedial prefrontal cortex group 1 metabotropic glutamate receptor function mediate resistance to extinction during protracted withdrawal from an extensive history of cocaine self-administration. J Neurosci 2013; 33:495-506a. [PMID: 23303930 PMCID: PMC3711633 DOI: 10.1523/jneurosci.3710-12.2013] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Revised: 09/28/2012] [Accepted: 10/21/2012] [Indexed: 11/21/2022] Open
Abstract
Anomalies in prefrontal cortex (PFC) function are posited to underpin difficulties in learning to suppress drug-seeking behavior during abstinence. Because group 1 metabotropic glutamate receptors (mGluRs) regulate drug-related learning, we assayed the consequences of extended access to intravenous cocaine (6 h/d; 0.25 mg/infusion for 10 d) on the PFC expression of group 1 mGluRs and the relevance of observed changes for cocaine seeking. After protracted withdrawal, cocaine-experienced animals exhibited a time-dependent intensification of cue-induced cocaine-seeking behavior and an impaired extinction of this behavior. These behavioral phenomena were associated with a time-dependent reduction in mGluR1/5 expression within ventromedial PFC (vmPFC) of cocaine-experienced animals exposed to extinction testing but not in untested ones. Interestingly, pharmacological manipulations of vmPFC mGluR1/5 produced no immediate effects on cue-induced cocaine-seeking behavior but produced residual effects on a subsequent test for cocaine seeking. At 3 d withdrawal, cocaine-experienced rats infused intra-vmPFC with mGluR1/5 antagonists, either before or after an initial test for cocaine seeking, persisted in their cocaine seeking akin to cocaine-experienced rats in protracted withdrawal. Conversely, cocaine-experienced rats infused with an mGluR1/5 agonist before the initial test for cocaine-seeking at 30 d withdrawal exhibited a facilitation of extinction learning. These data indicate that cue-elicited deficits in vmPFC group 1 mGluR function mediate resistance to extinction during protracted withdrawal from a history of extensive cocaine self-administration and pose pharmacological stimulation of these receptors as a potential approach to facilitate learned suppression of drug-seeking behavior that may aid drug abstinence.
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Affiliation(s)
- Osnat Ben-Shahar
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, California 93106-9660
| | - Arianne D. Sacramento
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, California 93106-9660
| | - Bailey W. Miller
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, California 93106-9660
| | - Sierra M. Webb
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, California 93106-9660
| | - Melissa G. Wroten
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, California 93106-9660
| | - Hannah E. Silva
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, California 93106-9660
| | - Amanda L. Caruana
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, California 93106-9660
| | - Evan J. Gordon
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, California 93106-9660
| | - Kyle L. Ploense
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, California 93106-9660
| | - Jennifer Ditzhazy
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, California 93106-9660
| | - Tod E. Kippin
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, California 93106-9660
| | - Karen K. Szumlinski
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, California 93106-9660
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44
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Hascup ER, Hascup KN, Talauliker PM, Price DA, Pomerleau F, Quintero JE, Huettl P, Gratton A, Strömberg I, Gerhardt GA. Sub-Second Measurements of Glutamate and Other Neurotransmitter Signaling Using Enzyme-Based Ceramic Microelectrode Arrays. NEUROMETHODS 2013. [DOI: 10.1007/978-1-62703-370-1_8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Cottone P, Wang X, Park JW, Valenza M, Blasio A, Kwak J, Iyer MR, Steardo L, Rice KC, Hayashi T, Sabino V. Antagonism of sigma-1 receptors blocks compulsive-like eating. Neuropsychopharmacology 2012; 37:2593-604. [PMID: 22713906 PMCID: PMC3473342 DOI: 10.1038/npp.2012.89] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2011] [Revised: 05/02/2012] [Accepted: 05/07/2012] [Indexed: 11/08/2022]
Abstract
Binge eating disorder is an addiction-like disorder characterized by episodes of rapid and excessive food consumption within discrete periods of time which occur compulsively despite negative consequences. This study was aimed at determining whether antagonism of Sigma-1 receptors (Sig-1Rs) blocked compulsive-like binge eating. We trained male wistar rats to obtain a sugary, highly palatable diet (Palatable group) or a regular chow diet (Chow control group), for 1 h a day under fixed ratio 1 operant conditioning. Following intake stabilization, we evaluated the effects of the selective Sig-1R antagonist BD-1063 on food responding. Using a light/dark conflict test, we also tested whether BD-1063 could block the time spent and the food eaten in an aversive, open compartment, where the palatable diet was offered. Furthermore, we measured Sig-1R mRNA and protein expression in several brain areas of the two groups, 24 h after the last binge session. Palatable rats rapidly developed binge-like eating, escalating the 1 h intake by four times, and doubling the eating rate and the regularity of food responding, compared to Chow rats. BD-1063 dose-dependently reduced binge-like eating and the regularity of food responding, and blocked the increased eating rate in Palatable rats. In the light/dark conflict test, BD-1063 antagonized the increased time spent in the aversive compartment and the increased intake of the palatable diet, without affecting motor activity. Finally, Palatable rats showed reduced Sig-1R mRNA expression in prefrontal and anterior cingulate cortices, and a two-fold increase in Sig-1R protein expression in anterior cingulate cortex compared to control Chow rats. These findings suggest that the Sig-1R system may contribute to the neurobiological adaptations driving compulsive-like eating, opening new avenues of investigation towards pharmacologically treating binge eating disorder.
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Affiliation(s)
- Pietro Cottone
- Laboratory of Addictive Disorders, Departments of Pharmacology and Psychiatry, Boston University School of Medicine, Boston, MA, USA
| | - Xiaofan Wang
- Laboratory of Addictive Disorders, Departments of Pharmacology and Psychiatry, Boston University School of Medicine, Boston, MA, USA
| | - Jin Won Park
- Laboratory of Addictive Disorders, Departments of Pharmacology and Psychiatry, Boston University School of Medicine, Boston, MA, USA
| | - Marta Valenza
- Laboratory of Addictive Disorders, Departments of Pharmacology and Psychiatry, Boston University School of Medicine, Boston, MA, USA
- Department of Pharmacology and Human Physiology, School of Medicine, University of Bari, Bari, Italy
| | - Angelo Blasio
- Laboratory of Addictive Disorders, Departments of Pharmacology and Psychiatry, Boston University School of Medicine, Boston, MA, USA
- Department of Physiology and Pharmacology, University of Rome La Sapienza, Rome, Italy
| | - Jina Kwak
- Laboratory of Addictive Disorders, Departments of Pharmacology and Psychiatry, Boston University School of Medicine, Boston, MA, USA
| | - Malliga R Iyer
- Chemical Biology Research Branch, National Institute on Drug Abuse and the National Institute on Alcohol Abuse and Alcoholism, Rockville, MD, USA
| | - Luca Steardo
- Department of Physiology and Pharmacology, University of Rome La Sapienza, Rome, Italy
| | - Kenner C Rice
- Chemical Biology Research Branch, National Institute on Drug Abuse and the National Institute on Alcohol Abuse and Alcoholism, Rockville, MD, USA
| | - Teruo Hayashi
- Cellular Stress Signaling Unit, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Valentina Sabino
- Laboratory of Addictive Disorders, Departments of Pharmacology and Psychiatry, Boston University School of Medicine, Boston, MA, USA
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Ago Y, Yano K, Araki R, Hiramatsu N, Kita Y, Kawasaki T, Onoe H, Chaki S, Nakazato A, Hashimoto H, Baba A, Takuma K, Matsuda T. Metabotropic glutamate 2/3 receptor antagonists improve behavioral and prefrontal dopaminergic alterations in the chronic corticosterone-induced depression model in mice. Neuropharmacology 2012; 65:29-38. [PMID: 23022081 DOI: 10.1016/j.neuropharm.2012.09.008] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2012] [Revised: 09/05/2012] [Accepted: 09/08/2012] [Indexed: 01/03/2023]
Abstract
Metabotropic glutamate 2/3 (mGlu2/3) receptor antagonists have an antidepressant-like effect, but the exact mechanism still remains unclear. This study examined the effects of mGlu2/3 receptor antagonists in chronic corticosterone-treated mice which could be used as an animal model of depression. In the forced swim test, the mGlu2/3 receptor antagonists MGS0039 (1.0 mg/kg, i.p.) and LY341495 (0.3 mg/kg, i.p) significantly reduced the increased immobility time of mice pretreated with corticosterone (20 mg/kg, s.c.) for 21 days, while desipramine (30 mg/kg, i.p.) and fluoxetine (30 mg/kg, i.p.) did not. The antidepressant-like effect of LY341495 was not blocked by the α-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptor antagonist NBQX (10 mg/kg, i.p.). Systemic administration of LY341495 did not affect basal release of glutamate, dopamine or serotonin in the prefrontal cortex of the control or chronic corticosterone-treated mice. Chronic corticosterone markedly enhanced high K(+)-induced release of dopamine, but not serotonin or glutamate, in the prefrontal cortex. This neurochemical change was blocked by systemic administration of MGS0039 and LY341495, but not desipramine or fluoxetine. These results suggest that chronic corticosterone-treated mice could be used as an animal model of treatment-resistant depression. This study also suggests that the prefrontal dopaminergic system is involved in the antidepressant-like effect of mGlu2/3 receptor antagonists in the chronic corticosterone-induced depression model.
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Affiliation(s)
- Yukio Ago
- Laboratory of Medicinal Pharmacology, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamada-oka, Suita, Osaka 565-0871, Japan
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Bowens NH, Dohare P, Kuo YH, Mongin AA. DCPIB, the proposed selective blocker of volume-regulated anion channels, inhibits several glutamate transport pathways in glial cells. Mol Pharmacol 2012; 83:22-32. [PMID: 23012257 DOI: 10.1124/mol.112.080457] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
4-(2-Butyl-6,7-dichloro-2-cyclopentyl-indan-1-on-5-yl) oxobutyric acid (DCPIB) was identified as the selective blocker of volume-regulated anion channels (VRAC). VRAC are permeable to small inorganic and organic anions, including the excitatory neurotransmitter glutamate. In recent years DCPIB has been increasingly used for probing the physiologic and pathologic roles of VRAC and was found to potently suppress pathologic glutamate release in cerebral ischemia. Because ischemic glutamate release can be mediated by a plethora of mechanisms, in this study we explored the selectivity of DCPIB toward the majority of previously identified glutamate transporters and permeability pathways. l-[(3)H]glutamate, d-[(3)H]aspartate, and l-[(14)C]cystine were used to trace amino acid release and uptake. We found that in addition to its well-characterized effect on VRAC, DCPIB potently inhibited glutamate release via connexin hemichannels and glutamate uptake via the glutamate transporter GLT-1 in rat glial cells. In contrast, DCPIB had no direct effect on vesicular glutamate release from rat brain synaptosomes or the cystine/glutamate exchange in astrocytes. The compound did not affect the astrocytic glutamate transporter GLAST, nor did it block glutamate release via the P2X(7)/pannexin permeability pathway. The ability of DCPIB to directly block connexin hemichannels was confirmed using a gene-specific siRNA knockdown approach. Overall, our data demonstrate that DCPIB influences several glutamate transport pathways and that its effects on VRAC in vivo should be verified using additional pharmacological controls.
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Affiliation(s)
- Nicole H Bowens
- Center for Neuropharmacology and Neuroscience, Albany Medical College, 47 New Scotland Avenue, Albany, NY 12208, USA
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Abstract
Pro-inflammatory stimuli evoke an export of glutamate from microglia that is sufficient to contribute to excitotoxicity in neighbouring neurons. Since microglia also express various glutamate receptors themselves, we were interested in the potential feedback of glutamate on this system. Several agonists of mGluRs (metabotropic glutamate receptors) were applied to primary rat microglia, and the export of glutamate into their culture medium was evoked by LPS (lipopolysaccharide). Agonists of group-II and -III mGluR ACPD [(1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid] and L-AP4 [L-(+)-2-amino-4-phosphonobutyric acid] were both capable of completely blocking the glutamate export without interfering with the production of NO (nitric oxide); the group-I agonist tADA (trans-azetidine-2,4-dicarboxylic acid) was ineffective. Consistent with the possibility of feedback, inhibition of mGluR by MSPG [(R,S)-α-2-methyl-4sulfonophenylglycine] potentiated glutamate export. As the group-II and -III mGluR are coupled to Gαi-containing G-proteins and the inhibition of adenylate cyclase, we explored the role of cAMP in this effect. Inhibition of cAMP-dependent protein kinase [also known as protein kinase A (PKA)] by H89 mimicked the effect of ACPD, and the mGluR agonist had its actions reversed by artificially sustaining cAMP through the PDE (phosphodiesterase) inhibitor IBMX (isobutylmethylxanthine) or the cAMP mimetic dbcAMP (dibutyryl cAMP). These data indicate that mGluR activation attenuates a potentially neurotoxic export of glutamate from activated microglia and implicate cAMP as a contributor to this aspect of microglial action.
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Abstracts of the Ninth International Symposium on Functional Neuroreceptor Mapping of the Living Brain. August 9-11, 2012. J Cereb Blood Flow Metab 2012; 32 Suppl 1:S13-196. [PMID: 22872875 PMCID: PMC3421080 DOI: 10.1038/jcbfm.2012.77] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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50
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Bridges R, Lutgen V, Lobner D, Baker DA. Thinking outside the cleft to understand synaptic activity: contribution of the cystine-glutamate antiporter (System xc-) to normal and pathological glutamatergic signaling. Pharmacol Rev 2012; 64:780-802. [PMID: 22759795 PMCID: PMC3400835 DOI: 10.1124/pr.110.003889] [Citation(s) in RCA: 159] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
System x(c)(-) represents an intriguing target in attempts to understand the pathological states of the central nervous system. Also called a cystine-glutamate antiporter, system x(c)(-) typically functions by exchanging one molecule of extracellular cystine for one molecule of intracellular glutamate. Nonvesicular glutamate released during cystine-glutamate exchange activates extrasynaptic glutamate receptors in a manner that shapes synaptic activity and plasticity. These findings contribute to the intriguing possibility that extracellular glutamate is regulated by a complex network of release and reuptake mechanisms, many of which are unique to glutamate and rarely depicted in models of excitatory signaling. Because system x(c)(-) is often expressed on non-neuronal cells, the study of cystine-glutamate exchange may advance the emerging viewpoint that glia are active contributors to information processing in the brain. It is noteworthy that system x(c)(-) is at the interface between excitatory signaling and oxidative stress, because the uptake of cystine that results from cystine-glutamate exchange is critical in maintaining the levels of glutathione, a critical antioxidant. As a result of these dual functions, system x(c)(-) has been implicated in a wide array of central nervous system diseases ranging from addiction to neurodegenerative disorders to schizophrenia. In the current review, we briefly discuss the major cellular components that regulate glutamate homeostasis, including glutamate release by system x(c)(-). This is followed by an in-depth discussion of system x(c)(-) as it relates to glutamate release, cystine transport, and glutathione synthesis. Finally, the role of system x(c)(-) is surveyed across a number of psychiatric and neurodegenerative disorders.
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Affiliation(s)
- Richard Bridges
- Department of Biomedical and Pharmaceutical Sciences, University of Montana, Missoula, Montana, USA
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