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Takahashi K, Sato K. The Conventional and Breakthrough Tool for the Study of L-Glutamate Transporters. MEMBRANES 2024; 14:77. [PMID: 38668105 PMCID: PMC11052088 DOI: 10.3390/membranes14040077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 02/26/2024] [Accepted: 03/21/2024] [Indexed: 04/28/2024]
Abstract
In our recent report, we clarified the direct interaction between the excitatory amino acid transporter (EAAT) 1/2 and polyunsaturated fatty acids (PUFAs) by applying electrophysiological and molecular biological techniques to Xenopus oocytes. Xenopus oocytes have a long history of use in the scientific field, but they are still attractive experimental systems for neuropharmacological studies. We will therefore summarize the pharmacological significance, advantages (especially in the study of EAAT2), and experimental techniques that can be applied to Xenopus oocytes; our new findings concerning L-glutamate (L-Glu) transporters and PUFAs; and the significant outcomes of our data. The data obtained from electrophysiological and molecular biological studies of Xenopus oocytes have provided us with further important questions, such as whether or not some PUFAs can modulate EAATs as allosteric modulators and to what extent docosahexaenoic acid (DHA) affects neurotransmission and thereby affects brain functions. Xenopus oocytes have great advantages in the studies about the interactions between molecules and functional proteins, especially in the case when the expression levels of the proteins are small in cell culture systems without transfections. These are also proper to study the mechanisms underlying the interactions. Based on the data collected in Xenopus oocyte experiments, we can proceed to the next step, i.e., the physiological roles of the compounds and their significances. In the case of EAAT2, the effects on the neurotransmission should be examined by electrophysiological approach using acute brain slices. For new drug development, pharmacokinetics pharmacodynamics (PKPD) data and blood brain barrier (BBB) penetration data are also necessary. In order not to miss the promising candidate compounds at the primary stages of drug development, we should reconsider using Xenopus oocytes in the early phase of drug development.
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Grants
- a Research Grant on Regulatory Harmonization and Evaluation of Pharmaceuticals, Medical Devices, Regenerative and Cellular Therapy Products, Gene Therapy Products, and Cosmetics from AMED, Japan Japan Agency for Medical Research and Development
- KAKENHI 18700373, 21700422, 17K08330 Ministry of Education, Culture, Sports, Science and Technology
- a Grant for the Program for Promotion of Fundamental Studies in Health Sciences of NIBIO National Institute of Biomedical Innovation, Health and Nutrition
- a grant for Research on Risks of Chemicals, a Labor Science Research Grant for Research on New Drug Development MHLW
- a Grant-in-Aid from Hoansha Foundation Hoansha Foundation
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Affiliation(s)
| | - Kaoru Sato
- Laboratory of Neuropharmacology, Division of Pharmacology, National Institute of Health Sciences, Kanagawa 210-9501, Japan;
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2
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Yakubov E, Schmid S, Hammer A, Chen D, Dahlmanns JK, Mitrovic I, Zurabashvili L, Savaskan N, Steiner HH, Dahlmanns M. Ferroptosis and PPAR-gamma in the limelight of brain tumors and edema. Front Oncol 2023; 13:1176038. [PMID: 37554158 PMCID: PMC10406130 DOI: 10.3389/fonc.2023.1176038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 07/04/2023] [Indexed: 08/10/2023] Open
Abstract
Human malignant brain tumors such as gliomas are devastating due to the induction of cerebral edema and neurodegeneration. A major contributor to glioma-induced neurodegeneration has been identified as glutamate. Glutamate promotes cell growth and proliferation in variety of tumor types. Intriguently, glutamate is also an excitatory neurotransmitter and evokes neuronal cell death at high concentrations. Even though glutamate signaling at the receptor and its downstream effectors has been extensively investigated at the molecular level, there has been little insight into how glutamate enters the tumor microenvironment and impacts on metabolic equilibration until recently. Surprisingly, the 12 transmembrane spanning tranporter xCT (SLC7A11) appeared to be a major player in this process, mediating glutamate secretion and ferroptosis. Also, PPARγ is associated with ferroptosis in neurodegeneration, thereby destroying neurons and causing brain swelling. Although these data are intriguing, tumor-associated edema has so far been quoted as of vasogenic origin. Hence, glutamate and PPARγ biology in the process of glioma-induced brain swelling is conceptually challenging. By inhibiting xCT transporter or AMPA receptors in vivo, brain swelling and peritumoral alterations can be mitigated. This review sheds light on the role of glutamate in brain tumors presenting the conceptual challenge that xCT disruption causes ferroptosis activation in malignant brain tumors. Thus, interfering with glutamate takes center stage in forming the basis of a metabolic equilibration approach.
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Affiliation(s)
- Eduard Yakubov
- Department of Neurosurgery, Paracelsus Medical University, Nuremberg, Germany
| | - Sebastian Schmid
- Department of Trauma, Orthopaedics, Plastic and Hand Surgery, University Hospital Augsburg, Augsburg, Germany
| | - Alexander Hammer
- Department of Neurosurgery, Paracelsus Medical University, Nuremberg, Germany
- Center for Spine and Scoliosis Therapy, Malteser Waldkrankenhaus St. Marien, Erlangen, Germany
| | - Daishi Chen
- Department of Otorhinolaryngology, Shenzhen People's Hospital, Jinan University, Shenzhen, China
| | - Jana Katharina Dahlmanns
- Institute for Physiology and Pathophysiology, Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Erlangen, Germany
| | - Ivana Mitrovic
- Department of Cardiac Surgery, Bogenhausen Hospital, Munich, Germany
| | | | - Nicolai Savaskan
- Department of Neurosurgery, University Medical School Hospital Universitätsklinikum Erlangen (UKER), Friedrich-Alexander Universität (FAU) Erlangen-Nürnberg, Erlangen, Germany
- Department of Public Health Neukölln, District Office Neukölln of Berlin Neukölln, Berlin, Germany
| | | | - Marc Dahlmanns
- Institute for Physiology and Pathophysiology, Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Erlangen, Germany
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3
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Jiang C, Wang H, Qi J, Li J, He Q, Wang C, Gao Y. Antidepressant effects of cherry leaf decoction on a chronic unpredictable mild stress rat model based on the Glu/GABA-Gln metabolic loop. Metab Brain Dis 2022; 37:2883-2901. [PMID: 36181653 DOI: 10.1007/s11011-022-01081-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Accepted: 09/04/2022] [Indexed: 01/10/2023]
Abstract
Cherry leaves (Prunus pseudocerasus Lindl. [Rosaceae]), a traditional Chinese herbal medicine, can regulate the factors closely related to depression including inflammatory cytokines, oxidative stress and blood glucose level. However, the antidepressant effects of cherry leaves and underlying neuromodulatory mechanisms remain relatively have not been elucidated explicitly. The present study investigated the antidepressant effects of cherry leaf decoction (CLD). The underlying neuromodulatory mechanism was explored by examining the glutamate (Glu)/γ-aminobutyric acid (GABA)-glutamine (Gln) metabolic loop. The chronic unpredictable mild stress (CUMS) rodent model was used in this study. The main flavonoids components of CLD were identified using high-performance liquid chromatography (HPLC). The antidepressant effects of CLD were assessed throughout behavioural tests including the bodyweight, sucrose preference test (SPT), forced swimming test (FPT) and tail suspension test (TST). Moreover, The baseline levels of serum adrenocorticotropic hormone (ACTH) and corticosterone (CORT) were quantified. The expression of proteins integrally involved in the Glu/GABA-Gln metabolic loop were observed and quantified by Western blotting, reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry. This study found that CLD ameliorated depressive-like behaviours induced by CUMS. The increase of serum ACTH and CORT baseline levels induced by CUMS was also reversed after CLD intervention. Furthermore, CUMS reduced the expression of GAD65, GAD67, GLT-1, GS and GABAA and increased NMDAR1 levels in the rat hippocampus, which was normalized by CLD treatment. The findings demonstrated that CLD could ameliorate the depression-like behaviours induced by CUMS, potentially through the inhibition of hypothalamic-pituitary-adrenal (HPA) axis hyperactivity and the regulation of Glu/GABA-Gln metabolic loop.
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Affiliation(s)
- Chuan Jiang
- Department of Preventive Medicine, Hebei University of Chinese Medicine, 3 Xingyuan Road, Shijiazhuang, 050200, Hebei, People's Republic of China
| | - Hua Wang
- Department of Preventive Medicine, Hebei University of Chinese Medicine, 3 Xingyuan Road, Shijiazhuang, 050200, Hebei, People's Republic of China
| | - Jiaying Qi
- Department of Pharmacy, Hebei University of Chinese Medicine, Shijiazhuang, 050200, Hebei, People's Republic of China
| | - Jinghan Li
- Department of Preventive Medicine, Hebei University of Chinese Medicine, 3 Xingyuan Road, Shijiazhuang, 050200, Hebei, People's Republic of China
| | - Qianqian He
- Department of Pharmacy, Hebei University of Chinese Medicine, Shijiazhuang, 050200, Hebei, People's Republic of China
| | - Chaonan Wang
- Department of Preventive Medicine, Hebei University of Chinese Medicine, 3 Xingyuan Road, Shijiazhuang, 050200, Hebei, People's Republic of China.
| | - Yonggang Gao
- Department of Preventive Medicine, Hebei University of Chinese Medicine, 3 Xingyuan Road, Shijiazhuang, 050200, Hebei, People's Republic of China.
- Hebei Key Laboratory of Chinese Medicine Research On Cardio-Cerebrovascular Disease, Shijiazhuang, 050200, Hebei, People's Republic of China.
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4
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Ayala-Lopez N, Watts SW. Physiology and Pharmacology of Neurotransmitter Transporters. Compr Physiol 2021; 11:2279-2295. [PMID: 34190339 DOI: 10.1002/cphy.c200035] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Regulation of the ability of a neurotransmitter [our focus: serotonin, norepinephrine, dopamine, acetylcholine, glycine, and gamma-aminobutyric acid (GABA)] to reach its receptor targets is regulated in part by controlling the access the neurotransmitter has to receptors. Transporters, located at both the cellular plasma membrane and in subcellular vesicles, carry a myriad of responsibilities that include enabling neurotransmitter release and controlling uptake of neurotransmitter back into a cell or vesicle. Driven largely by electrochemical gradients, these transporters move neurotransmitters. The regulation of the transporters themselves through changes in expression and/or posttranslational modification allows for fine-tuning of this system. Transporters have been best recognized as targets for psychoactive stimulants and remain a mainstay target of primarily central nervous system (CNS) acting drugs for treatment of debilitating diseases such as depression and anxiety. Studies reveal, however, that transporters are found and functional in tissues outside the CNS (gastrointestinal and cardiovascular tissues, for example). The importance of neurotransmitter transporters is underscored with discoveries that dysfunction of transporters can cause life-changing disease. This article provides a high-level review of major classes of both plasma membrane transporters and vesicular transporters. © 2021 American Physiological Society. Compr Physiol 11:2279-2295, 2021.
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Affiliation(s)
- Nadia Ayala-Lopez
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Stephanie W Watts
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan, USA
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5
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Ravindra S, Irfana Jesin CP, Shabashini A, Nandi GC. Recent Advances in the Preparations and Synthetic Applications of Oxaziridines and Diaziridines. Adv Synth Catal 2021. [DOI: 10.1002/adsc.202001372] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Sundaresan Ravindra
- Department of Chemistry National Institute of Technology Tiruchirappalli 620015, Tamilnadu India
| | - C. P. Irfana Jesin
- Department of Chemistry National Institute of Technology Tiruchirappalli 620015, Tamilnadu India
| | - Arivalagan Shabashini
- Department of Chemistry National Institute of Technology Tiruchirappalli 620015, Tamilnadu India
| | - Ganesh Chandra Nandi
- Department of Chemistry National Institute of Technology Tiruchirappalli 620015, Tamilnadu India
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6
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Liu N, Jensen AA, Bunch L. β-Indolyloxy Functionalized Aspartate Analogs as Inhibitors of the Excitatory Amino Acid Transporters (EAATs). ACS Med Chem Lett 2020; 11:2212-2220. [PMID: 33214831 DOI: 10.1021/acsmedchemlett.0c00342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 08/26/2020] [Indexed: 11/28/2022] Open
Abstract
The excitatory amino acid transporters (EAATs) mediate uptake of the major excitatory neurotransmitter l-glutamate (Glu). The essential functions governed by these transporters in regulating the central Glu level make them interesting therapeutic targets in a wide range of neurodegenerative and psychiatric disorders. l-Aspartate (Asp), another EAAT substrate, has served as a privileged scaffold for the development of EAAT inhibitors. In this study, we designed and synthesized the first β-indolyloxy Asp analogs 15a-d with the aim to probe a hitherto unexplored adjacent pocket to the substrate binding site. The pharmacological properties of 15a-d were characterized at hEAAT1-3 and rEAAT4 in a conventional [3H]-d-Asp uptake assay. Notably, thiophene analog 15b and the para-trifluoromethyl phenyl analog 15d were found to be hEAAT1,2-preferring inhibitors exhibiting IC50 values in the high nanomolar range (0.21-0.71 μM) at these two transporters versus IC50 values in the low micromolar range at EAAT3,4 (1.6-8.9 μM). In summary, the results presented herein open up for further structure-activity relationship studies of this new scaffold.
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Affiliation(s)
- Na Liu
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Anders A Jensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Lennart Bunch
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
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7
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Tang Z, Yang F, Dong Y, Ma C, Sun S, Shan Y, Zhang Y, Liu H. Midazolam contributes to neuroprotection against hypoxia/reoxygenation-induced brain injury in neonatal rats via regulation of EAAT2. Brain Res Bull 2020; 161:136-146. [DOI: 10.1016/j.brainresbull.2020.04.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 03/18/2020] [Accepted: 04/20/2020] [Indexed: 01/22/2023]
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8
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Wu P, Bjørn-Yoshimoto WE, Staudt M, Jensen AA, Bunch L. Identification and Structure-Activity Relationship Study of Imidazo[1,2- a]pyridine-3-amines as First Selective Inhibitors of Excitatory Amino Acid Transporter Subtype 3 (EAAT3). ACS Chem Neurosci 2019; 10:4414-4429. [PMID: 31573179 DOI: 10.1021/acschemneuro.9b00447] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
In the present study, screening of a library of 49,087 compounds at the excitatory amino acid transporter subtype 3 (EAAT3) led to the identification of 2-(furan-2-yl)-8-methyl-N-(o-tolyl)imidazo[1,2-a]pyridin-3-amine (3a) which showed a >20-fold preference for inhibition of EAAT3 (IC50 = 13 μM) over EAAT1,2,4 (EAAT1: IC50 ∼ 250 μM; EAAT2,4: IC50 > 250 μM). It was shown that a small lipophilic substituent (methyl or bromine) at the 7- and/or 8-position was essential for activity. Furthermore, the substitution pattern of the o-tolyl group (compound 5b) and the chemical nature of the substituent in the 2-position (compound 7b) were shown to be essential for the selectivity toward EAAT3 over EAAT1,2. The most prominent analogues to come out of this study are 3a and 3e that display ∼35-fold selectivity for EAAT3 (IC50 = 7.2 μM) over EAAT1,2,4 (IC50 ∼ 250 μM).
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Affiliation(s)
- Peng Wu
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2100, Denmark
| | - Walden E. Bjørn-Yoshimoto
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2100, Denmark
| | - Markus Staudt
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2100, Denmark
| | - Anders A. Jensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2100, Denmark
| | - Lennart Bunch
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2100, Denmark
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9
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Falcucci RM, Wertz R, Green JL, Meucci O, Salvino J, Fontana ACK. Novel Positive Allosteric Modulators of Glutamate Transport Have Neuroprotective Properties in an in Vitro Excitotoxic Model. ACS Chem Neurosci 2019; 10:3437-3453. [PMID: 31257852 DOI: 10.1021/acschemneuro.9b00061] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Dysfunction of excitatory amino acid transporters (EAATs) has been implicated in the pathogenesis of various neurological disorders, such as stroke, brain trauma, epilepsy, and several neurodegenerative disorders. EAAT2 is the main transporter subtype responsible for glutamate clearance in the brain, and plays a key role in regulating neurotransmission and preventing excitotoxicity. Therefore, compounds that increase the activity of EAAT2 have therapeutic potential for neuroprotection. In previous studies, we used virtual screening approaches to identify novel positive allosteric modulators (PAMs) of EAAT2. These compounds were shown to selectively increase the activity of EAAT2 and increase Vmax of transport, without changing substrate affinity. In this work, our major effort was to investigate whether increasing the activity of EAAT2 by allosteric modulation would translate to neuroprotection in in vitro primary culture models of excitotoxicity. To investigate potential neuroprotective effects of one EAAT2 PAM, GT949, we subjected cultures to acute and prolonged excitotoxic insults by exogenous application of glutamate, or oxidative stress by application of hydrogen peroxide. GT949 administration did not result in neuroprotection in the oxidative stress model, likely due to damage of the glutamate transporters. However, GT949 displayed neuroprotective properties after acute and prolonged glutamate-mediated excitotoxicity. We propose that this compound prevents excess glutamate signaling by increasing the rate of glutamate clearance by EAAT2, thereby preventing excitotoxic damage and cell death. This novel class of compounds is therefore an innovative approach for neuroprotection with potential for translation in in vivo animal models of excitotoxicity.
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Affiliation(s)
- Romulo Martelli Falcucci
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, United States
| | - Ryan Wertz
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, United States
| | - Jennifer Leigh Green
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, United States
| | - Olimpia Meucci
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, United States
| | - Joseph Salvino
- The Wistar Institute, Philadelphia, Pennsylvania 19104, United States
| | - Andréia Cristina Karklin Fontana
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, United States
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10
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Schizophrenia and Parkinson’s disease: Selected therapeutic advances beyond the dopaminergic etiologies. ALEXANDRIA JOURNAL OF MEDICINE 2019. [DOI: 10.1016/j.ajme.2013.03.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
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11
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Gegelashvili G, Bjerrum OJ. Glutamate transport system as a key constituent of glutamosome: Molecular pathology and pharmacological modulation in chronic pain. Neuropharmacology 2019; 161:107623. [PMID: 31047920 DOI: 10.1016/j.neuropharm.2019.04.029] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 04/26/2019] [Accepted: 04/28/2019] [Indexed: 01/07/2023]
Abstract
Neural uptake of glutamate is executed by the structurally related members of the SLC1A family of solute transporters: GLAST/EAAT1, GLT-1/EAAT2, EAAC1/EAAT3, EAAT4, ASCT2. These plasma membrane proteins ensure supply of glutamate, aspartate and some neutral amino acids, including glutamine and cysteine, for synthetic, energetic and signaling purposes, whereas effective removal of glutamate from the synaptic cleft shapes excitatory neurotransmission and prevents glutamate toxicity. Glutamate transporters (GluTs) possess also receptor-like properties and can directly initiate signal transduction. GluTs are physically linked to other glutamate signaling-, transporting- and metabolizing molecules (e.g., glutamine transporters SNAT3 and ASCT2, glutamine synthetase, NMDA receptor, synaptic vesicles), as well as cellular machineries fueling the transmembrane transport of glutamate (e.g., ion gradient-generating Na/K-ATPase, glycolytic enzymes, mitochondrial membrane- and matrix proteins, glucose transporters). We designate this supramolecular functional assembly as 'glutamosome'. GluTs play important roles in the molecular pathology of chronic pain, due to the predominantly glutamatergic nature of nociceptive signaling in the spinal cord. Down-regulation of GluTs often precedes or occurs simultaneously with development of pain hypersensitivity. Pharmacological inhibition or gene knock-down of spinal GluTs can induce/aggravate pain, whereas enhancing expression of GluTs by viral gene transfer can mitigate chronic pain. Thus, functional up-regulation of GluTs is turning into a prospective pharmacotherapeutic approach for the management of chronic pain. A number of novel positive pharmacological regulators of GluTs, incl. pyridazine derivatives and β-lactams, have recently been introduced. However, design and development of new analgesics based on this principle will require more precise knowledge of molecular mechanisms underlying physiological or aberrant functioning of the glutamate transport system in nociceptive circuits. This article is part of the issue entitled 'Special Issue on Neurotransmitter Transporters'.
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Affiliation(s)
- Georgi Gegelashvili
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark; Institute of Chemical Biology, Ilia State University, Tbilisi, Georgia.
| | - Ole Jannik Bjerrum
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
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12
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Yamamoto K, Mifflin S. Inhibition of glial glutamate transporter GLT1 in the nucleus of the solitary tract attenuates baroreflex control of sympathetic nerve activity and heart rate. Physiol Rep 2018; 6:e13877. [PMID: 30230240 PMCID: PMC6144441 DOI: 10.14814/phy2.13877] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 08/22/2018] [Accepted: 08/31/2018] [Indexed: 02/02/2023] Open
Abstract
The astrocytic glutamate transporter (GLT1) plays an important role in the maintenance of extracellular glutamate concentration below neurotoxic levels in brain. However, the functional role of GLT1 within the nucleus of the solitary tract (NTS) in the regulation of cardiovascular function remains unclear. We examined the effect of inhibiting GLT1 in the subpostremal NTS on mean arterial pressure (MAP), renal sympathetic nerve activity (RSNA) and heart rate (HR) in anesthetized, artificially ventilated rats. It was found that dihydrokainate (DHK; inhibitor of GLT1, 5 mmol/L, 100 nL) injections into the NTS (n = 6) decreased MAP (50 ± 10 mmHg, mean ± SD), RSNA (89 ± 14%) and HR (37 ± 6 bpm). Pretreatment with kynurenate (KYN; glutamate receptor antagonist, 5 mmol/L, 30 μL) topically applied to the dorsal surface of the brainstem (n = 4) attenuated the responses to NTS injections of DHK (P < 0.01). The effect of DHK on arterial baroreflex function was examined using i.v. infusions of phenylephrine and nitroprusside. DHK reduced baroreflex response range (maximum-minimum) of RSNA by 91 ± 2% and HR by 83 ± 5% (n = 6, P < 0.001). These results indicate that inhibition of GLT1 within the NTS decreases MAP, RSNA, and HR by the activation of ionotropic glutamate receptors. As a result, baroreflex control of RSNA and HR was dramatically attenuated. The astrocytic glutamate transporter in the NTS plays an important role in the maintenance and regulation of cardiovascular function.
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Affiliation(s)
- Kenta Yamamoto
- Department of Physiology and AnatomyUniversity of North Texas Health Science CentreFort WorthTexas
- Faculty of Pharmaceutical SciencesTeikyo Heisei UniversityTokyoJapan
| | - Steve Mifflin
- Department of Physiology and AnatomyUniversity of North Texas Health Science CentreFort WorthTexas
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13
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Fu H, Zhang J, Tepper PG, Bunch L, Jensen AA, Poelarends GJ. Chemoenzymatic Synthesis and Pharmacological Characterization of Functionalized Aspartate Analogues As Novel Excitatory Amino Acid Transporter Inhibitors. J Med Chem 2018; 61:7741-7753. [PMID: 30011368 PMCID: PMC6139576 DOI: 10.1021/acs.jmedchem.8b00700] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
![]()
Aspartate (Asp) derivatives are privileged
compounds for investigating
the roles governed by excitatory amino acid transporters (EAATs) in
glutamatergic neurotransmission. Here, we report the synthesis of
various Asp derivatives with (cyclo)alkyloxy and (hetero)aryloxy substituents
at C-3. Their pharmacological properties were characterized at the
EAAT1–4 subtypes. The l-threo-3-substituted
Asp derivatives 13a–e and 13g–k were nonsubstrate inhibitors, exhibiting pan
activity at EAAT1–4 with IC50 values ranging from
0.49 to 15 μM. Comparisons between (dl-threo)-19a–c and (dl-erythro)-19a–c Asp analogues
confirmed that the threo configuration is crucial
for the EAAT1–4 inhibitory activities. Analogues (3b–e) of l-TFB-TBOA (3a)
were shown to be potent EAAT1–4 inhibitors, with IC50 values ranging from 5 to 530 nM. Hybridization of the nonselective
EAAT inhibitor l-TBOA with EAAT2-selective inhibitor WAY-213613
or EAAT3-preferring inhibitor NBI-59159 yielded compounds 8 and 9, respectively, which were nonselective EAAT inhibitors
displaying considerably lower IC50 values at EAAT1–4
(11–140 nM) than those displayed by the respective parent molecules.
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Affiliation(s)
- Haigen Fu
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy , University of Groningen , Antonius Deusinglaan 1 , 9713 AV Groningen , The Netherlands
| | - Jielin Zhang
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy , University of Groningen , Antonius Deusinglaan 1 , 9713 AV Groningen , The Netherlands
| | - Pieter G Tepper
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy , University of Groningen , Antonius Deusinglaan 1 , 9713 AV Groningen , The Netherlands
| | - Lennart Bunch
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences , University of Copenhagen , DK-2100 Copenhagen OE , Denmark
| | - Anders A Jensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences , University of Copenhagen , DK-2100 Copenhagen OE , Denmark
| | - Gerrit J Poelarends
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy , University of Groningen , Antonius Deusinglaan 1 , 9713 AV Groningen , The Netherlands
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14
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Pál B. Involvement of extrasynaptic glutamate in physiological and pathophysiological changes of neuronal excitability. Cell Mol Life Sci 2018; 75:2917-2949. [PMID: 29766217 PMCID: PMC11105518 DOI: 10.1007/s00018-018-2837-5] [Citation(s) in RCA: 79] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 04/27/2018] [Accepted: 05/07/2018] [Indexed: 12/14/2022]
Abstract
Glutamate is the most abundant neurotransmitter of the central nervous system, as the majority of neurons use glutamate as neurotransmitter. It is also well known that this neurotransmitter is not restricted to synaptic clefts, but found in the extrasynaptic regions as ambient glutamate. Extrasynaptic glutamate originates from spillover of synaptic release, as well as from astrocytes and microglia. Its concentration is magnitudes lower than in the synaptic cleft, but receptors responding to it have higher affinity for it. Extrasynaptic glutamate receptors can be found in neuronal somatodendritic location, on astroglia, oligodendrocytes or microglia. Activation of them leads to changes of neuronal excitability with different amplitude and kinetics. Extrasynaptic glutamate is taken up by neurons and astrocytes mostly via EAAT transporters, and astrocytes, in turn metabolize it to glutamine. Extrasynaptic glutamate is involved in several physiological phenomena of the central nervous system. It regulates neuronal excitability and synaptic strength by involving astroglia; contributing to learning and memory formation, neurosecretory and neuromodulatory mechanisms, as well as sleep homeostasis.The extrasynaptic glutamatergic system is affected in several brain pathologies related to excitotoxicity, neurodegeneration or neuroinflammation. Being present in dementias, neurodegenerative and neuropsychiatric diseases or tumor invasion in a seemingly uniform way, the system possibly provides a common component of their pathogenesis. Although parts of the system are extensively discussed by several recent reviews, in this review I attempt to summarize physiological actions of the extrasynaptic glutamate on neuronal excitability and provide a brief insight to its pathology for basic understanding of the topic.
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Affiliation(s)
- Balázs Pál
- Department of Physiology, Faculty of Medicine, University of Debrecen, Nagyerdei krt 98, Debrecen, 4012, Hungary.
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15
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Kadriu B, Yuan S, Farmer C, Nugent AC, Lener MS, Niciu MJ, Park M, Yazdian A, Ballard ED, Henn FA, Henter ID, Park LT, Zarate CA. Clinical Trial of the Potassium Channel Activator Diazoxide for Major Depressive Disorder Halted Due to Intolerability. J Clin Psychopharmacol 2018; 38:243-246. [PMID: 29601316 PMCID: PMC5903962 DOI: 10.1097/jcp.0000000000000866] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
BACKGROUND Some glutamatergic modulators have demonstrated rapid and relatively sustained antidepressant properties in patients with major depressive disorder. Because the potassium channel activator diazoxide increases glutamate uptake via potassium channel activation, we hypothesized that it might exert antidepressant effects by increasing the removal of glutamate from the synaptic cleft, thereby reducing excessive glutamate transmission. METHODS This randomized, double-blind, placebo-controlled, crossover, single-site inpatient clinical study was conducted at the National Institute of Mental Health to assess the efficacy and safety of a 3-week course of diazoxide (200-400 mg daily, twice a day) versus a 3-week course of placebo in 6 participants with treatment-refractory major depressive disorder. The primary clinical outcome measure was change in Montgomery-Asberg Depression Rating Scale score from baseline to posttreatment. Quantitative insulin sensitivity check index, as well as concomitant imaging measures (electroencephalography, proton magnetic resonance spectroscopy, magnetoencephalography), were used as potential surrogate markers of target (KATP channel) engagement. RESULTS The study was halted due to severe adverse effects. Given the small sample size, statistical evaluation of the effect of diazoxide on Montgomery-Asberg Depression Rating Scale scores or the imaging measures was not pursued. Visual inspection of the quantitative insulin sensitivity check index test revealed no evidence of target engagement. CONCLUSIONS Although the results are negative, they are an important addition to the literature in this rapidly changing field.
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Affiliation(s)
- Bashkim Kadriu
- Experimental Therapeutics and Pathophysiology Branch, Intramural Research Program, National Institute of Mental Health, Bethesda, MD, USA
| | - Shiwen Yuan
- Experimental Therapeutics and Pathophysiology Branch, Intramural Research Program, National Institute of Mental Health, Bethesda, MD, USA
| | - Cristan Farmer
- Experimental Therapeutics and Pathophysiology Branch, Intramural Research Program, National Institute of Mental Health, Bethesda, MD, USA
| | - Allison C. Nugent
- Experimental Therapeutics and Pathophysiology Branch, Intramural Research Program, National Institute of Mental Health, Bethesda, MD, USA
| | - Marc S. Lener
- Experimental Therapeutics and Pathophysiology Branch, Intramural Research Program, National Institute of Mental Health, Bethesda, MD, USA
| | - Mark J. Niciu
- Experimental Therapeutics and Pathophysiology Branch, Intramural Research Program, National Institute of Mental Health, Bethesda, MD, USA
| | - Minkyung Park
- Experimental Therapeutics and Pathophysiology Branch, Intramural Research Program, National Institute of Mental Health, Bethesda, MD, USA
| | - Aaron Yazdian
- Experimental Therapeutics and Pathophysiology Branch, Intramural Research Program, National Institute of Mental Health, Bethesda, MD, USA
| | - Elizabeth D. Ballard
- Experimental Therapeutics and Pathophysiology Branch, Intramural Research Program, National Institute of Mental Health, Bethesda, MD, USA
| | - Fritz A. Henn
- Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Ioline D. Henter
- Experimental Therapeutics and Pathophysiology Branch, Intramural Research Program, National Institute of Mental Health, Bethesda, MD, USA
| | - Lawrence T. Park
- Experimental Therapeutics and Pathophysiology Branch, Intramural Research Program, National Institute of Mental Health, Bethesda, MD, USA
| | - Carlos A Zarate
- Experimental Therapeutics and Pathophysiology Branch, Intramural Research Program, National Institute of Mental Health, Bethesda, MD, USA
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16
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Kortagere S, Mortensen OV, Xia J, Lester W, Fang Y, Srikanth Y, Salvino JM, Fontana ACK. Identification of Novel Allosteric Modulators of Glutamate Transporter EAAT2. ACS Chem Neurosci 2018; 9:522-534. [PMID: 29140675 DOI: 10.1021/acschemneuro.7b00308] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Dysfunction of excitatory amino acid transporters (EAATs) has been implicated in the pathogenesis of various neurological disorders, such as stroke, brain trauma, epilepsy, and neurodegenerative diseases, among others. EAAT2 is the main subtype responsible for glutamate clearance in the brain, having a key role in regulating transmission and preventing excitotoxicity. Therefore, compounds that increase the expression or activity of EAAT2 have therapeutic potential for neuroprotection. Previous studies identified molecular determinants for EAAT2 transport stimulation in a structural domain that lies at the interface of the rigid trimerization domain and the central substrate binding transport domain. In this work, a hybrid structure based approach was applied, based on this molecular domain, to create a high-resolution pharmacophore. Subsequently, virtual screening of a library of small molecules was performed, identifying 10 hit molecules that interact at the proposed domain. Among these, three compounds were determined to be activators, four were inhibitors, and three had no effect on EAAT2-mediated transport in vitro. Further characterization of the two best ranking EAAT2 activators for efficacy, potency, and selectivity for glutamate over monoamine transporters subtypes and NMDA receptors and for efficacy in cultured astrocytes is demonstrated. Mutagenesis studies suggest that the EAAT2 activators interact with residues forming the interface between the trimerization and transport domains. These compounds enhance the glutamate translocation rate, with no effect on substrate interaction, suggesting an allosteric mechanism. The identification of these novel positive allosteric modulators of EAAT2 offers an innovative approach for the development of therapies based on glutamate transport enhancement.
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Affiliation(s)
- Sandhya Kortagere
- Department of Microbiology and Immunology, Centers for Molecular Parasitology, Virology and Translational Neuroscience, Institute for Molecular Medicine, Drexel University College of Medicine, Philadelphia, Pennsylvania 19129, United States
| | - Ole V. Mortensen
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, United States
| | - Jingsheng Xia
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, United States
| | - William Lester
- Analytical Chemistry, Division of Pre-Clinical Innovation (DPI), NCATS, National Institutes of Health, Rockville, Maryland 20850, United States
| | - Yuhong Fang
- Analytical Chemistry, Division of Pre-Clinical Innovation (DPI), NCATS, National Institutes of Health, Rockville, Maryland 20850, United States
| | - Yellamelli Srikanth
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, United States
| | - Joseph M. Salvino
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, United States
| | - Andréia C. K. Fontana
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, United States
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17
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Huang S, Tong H, Lei M, Zhou M, Guo W, Li G, Tang X, Li Z, Mo M, Zhang X, Chen X, Cen L, Wei L, Xiao Y, Li K, Huang Q, Yang X, Liu W, Zhang L, Qu S, Li S, Xu P. Astrocytic glutamatergic transporters are involved in Aβ-induced synaptic dysfunction. Brain Res 2017; 1678:129-137. [PMID: 29066369 DOI: 10.1016/j.brainres.2017.10.011] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2017] [Revised: 10/10/2017] [Accepted: 10/11/2017] [Indexed: 01/15/2023]
Abstract
In Alzheimer's disease (AD), dementia severity correlates most strongly with decreased synapse density in the hippocampus and cerebral cortex. Although studies in rodents have established that hippocampal long-term potentiation (LTP) is inhibited by soluble oligomers of beta-amyloid (Aβ), the synaptic mechanisms remain unclear. Here, field excitatory postsynaptic potentials (fEPSP) recordings were made in the CA1 region of mouse hippocampal slices. The medium of APP-expressing CHO cells, which contain soluble forms of Aβ including small oligomers, inhibited LTP and facilitated long-term depression (LTD), thus making the LTP/LTD curve shift toward the right. This phenomenon could be mimicked by the non-selective glutamate transporter inhibitor, DL-TBOA. More specifically, the Aβ impaired LTP and facilitated LTD were occluded by the selective astrocytic glutamate transporter inhibitors, TFB-TBOA. In cultured astrocytes, the Aβ oligomers also decrease astrocytic glutamate transporters (EAAT1, EAAT2) expression. We conclude that soluble Aβ oligomers decrease the activation of astrocytic glutamate transporters, thereby impairing synaptic plasticity.
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Affiliation(s)
- Shuxuan Huang
- Department of Neurology, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong 510120, China
| | - Huichun Tong
- Clinical Medicine Research Centre, Shunde Hospital, Southern Medical University, Foshan, Guangdong 528300, China; Department of Neurology, Shunde Hospital, Southern Medical University, Foshan, Guangdong 528300, China
| | - Ming Lei
- Department of Neurology, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong 510120, China; Department of Neurology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, China
| | - Miaomiao Zhou
- Department of Neurology, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong 510120, China
| | - Wenyuan Guo
- Department of Neurology, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong 510120, China
| | - Guihua Li
- Department of Neurology, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong 510120, China
| | - Xiaolu Tang
- Department of Neurology, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong 510120, China
| | - Zhe Li
- Department of Neurology, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong 510120, China
| | - Mingshu Mo
- Department of Neurology, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong 510120, China
| | - Xiuping Zhang
- Teaching Center of Experimental Medicine, School of Basic Medical Sciences, Southern Medical University, Guangzhou, Guangdong 510515, China
| | - Xiang Chen
- Department of Neurology, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong 510120, China
| | - Luan Cen
- Department of Neurology, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong 510120, China
| | - Lei Wei
- Department of Neurology, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510082, China
| | - Yousheng Xiao
- Department of Neurology, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong 510120, China
| | - Kaiping Li
- State Key Laboratory of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong 510120, China
| | - Qinghui Huang
- Department of Neurology, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong 510120, China; State Key Laboratory of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong 510120, China
| | - Xinling Yang
- Department of Neurology, The Third Affiliated Hospital of Xinjiang Medical University, Urumqi, Xinjiang 830011, China
| | - Weiguo Liu
- Department of Geroatric&Neurology, Affiliated Brain Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, China
| | - Li Zhang
- Department of Geroatric&Neurology, Affiliated Brain Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, China
| | - Shaogang Qu
- Clinical Medicine Research Centre, Shunde Hospital, Southern Medical University, Foshan, Guangdong 528300, China; Department of Neurology, Shunde Hospital, Southern Medical University, Foshan, Guangdong 528300, China.
| | - Shaomin Li
- Department of Neurology, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong 510120, China; Ann Romney Center for Neurologic Disease, Brigham and Women's Hospital of Harvard Medical School, Boston, MA 02115, USA.
| | - Pingyi Xu
- Department of Neurology, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong 510120, China.
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18
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Drugs to Alter Extracellular Concentration of Glutamate: Modulators of Glutamate Uptake Systems. ACTA ACUST UNITED AC 2017. [DOI: 10.1007/978-1-4939-7228-9_7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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19
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Oliveira DR, Luchez CV, Bortolotto ZA, Fernandes JPS. Evaluation of β-Aminocarboxylic Acid Derivatives in Hippocampal Excitatory Synaptic Transmission. Arch Pharm (Weinheim) 2017; 350. [PMID: 28872703 DOI: 10.1002/ardp.201700179] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2017] [Revised: 08/08/2017] [Accepted: 08/10/2017] [Indexed: 11/09/2022]
Abstract
β-Aminocarboxylic acid derivatives (LINS04 series) were screened with the aim to explore their potential functional role in excitatory synaptic transmission in the central nervous system. We used field recordings in rat hippocampal slices to investigate the effects of the LINS04 series on the synaptic transmission at hippocampal CA1 synapses. We found that LINS04008 and LINS04009 increase the size of the evoked field excitatory postsynaptic potential (EPSP) in a dose-dependent manner. The concentration-response curve shows that the efficacy of LINS04008 is highest in the series (EC50 = 91.32 µM; maximum fEPSP 44.97%). The esters LINS04006 and LINS04005 did not affect the synaptic evoked activity. These data provide the first evidence of synaptic activity enhancement by these compounds and the importance of the acidic group to the activity. This set of data may provide direction for a strategic procedure to restore the glutamate synaptic transmission; however, further studies are needed to establish a more complete picture of how these molecules act on the glutamate transmission, which are in our mind for the next steps.
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Affiliation(s)
- Daniela R Oliveira
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience University of Bristol, Bristol, UK
| | - Cibele V Luchez
- Departamento de Ciências Farmacêuticas, Universidade Federal de São Paulo, Diadema-SP, Brazil
| | - Zuner A Bortolotto
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience University of Bristol, Bristol, UK
| | - João P S Fernandes
- Departamento de Ciências Farmacêuticas, Universidade Federal de São Paulo, Diadema-SP, Brazil
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20
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Ding XF, Li YH, Chen JX, Sun LJ, Jiao HY, Wang XX, Zhou Y. Involvement of the glutamate/glutamine cycle and glutamate transporter GLT-1 in antidepressant-like effects of Xiao Yao san on chronically stressed mice. BMC COMPLEMENTARY AND ALTERNATIVE MEDICINE 2017; 17:326. [PMID: 28629384 PMCID: PMC5477120 DOI: 10.1186/s12906-017-1830-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Accepted: 06/07/2017] [Indexed: 11/10/2022]
Abstract
BACKGROUND Xiao Yao San (XYS) is an herbal prescription which is used in the treatment of depression for thousands of years from Song dynasty in China (960-1127 A.D.), and is the bestselling and most popular herb formula for treating major depression. This study aimed to assess the chronic antidepressant effects of XYS and fluoxetine in depressed mice induced by chronic unpredictable mild stress (CUMS) and its association with alterations in glutamate/glutamine cycle and glutamate transporters. METHODS Mice in the control and model group were given 0.5 ml physiological saline by intragastric administration. Mice in two treatment groups were given XYS (0.25 g/kg/d) and fluoxetine (2.6 mg/kg/d), respectively. The depressive-like behaviors such as forced swim test (FST), sucrose preference test (SPT) and novelty-suppressed feeding (NSF) test were measured after mice exposed to CUMS for 21 days. Body weight, contents of glutamate and glutamine, glutamine/glutamate ratio that is usually thought to reflect glutamate/glutamine cycle, and the protein and mRNA expressions of glutamate transporters (excitatory amino acid transporter 1-2,GLAST/EAAT1 and GLT-1/EAAT2) were measured. The immunoreactivities of GLAST and GLT-1 in the hippocampus were also investigated. RESULTS After CUMS exposure, mice exhibited depressive-like behaviors, body weight loss, increased glutamate level, decreased glutamine level, elevated glutamine/glutamate ratio, decreased GLT-1 protein expression and mRNA level, and decreased average optical density (AOD) of GLT-1 in the CA1, CA3 and DG in the hippocampus. These abnormalities could be effectively reversed by XYS or fluoxetine treatment. In addition, the study also found that GLAST expression in the hippocampus could not be altered by 21-d CUMS. CONCLUSION The studies indicated that XYS may have therapeutic actions on depression -like behavior s induced by CUMS in mice possibly mediated by modulation of glutamate/glutamine cycle and glutamate transporter GLT-1 in the hippocampus.
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Affiliation(s)
- Xiu-Fang Ding
- School of Basic Medical Science, Beijing University of Chinese Medicine, Beijing, 100029 China
| | - Yue-Hua Li
- Beijing Chaoyang Hospital, Capital Medical University, Beijing, 100043 China
| | - Jia-Xu Chen
- School of Basic Medical Science, Beijing University of Chinese Medicine, Beijing, 100029 China
| | - Long-Ji Sun
- School of Basic Medical Science, Beijing University of Chinese Medicine, Beijing, 100029 China
| | - Hai-Yan Jiao
- School of Basic Medical Science, Beijing University of Chinese Medicine, Beijing, 100029 China
| | - Xin-Xin Wang
- School of Basic Medicine, Henan University of TCM, Henan, 450046 Henan China
| | - Yan Zhou
- School of Basic Medical Science, Beijing University of Chinese Medicine, Beijing, 100029 China
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21
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Fu H, Younes SHH, Saifuddin M, Tepper PG, Zhang J, Keller E, Heeres A, Szymanski W, Poelarends GJ. Rapid chemoenzymatic route to glutamate transporter inhibitorl-TFB-TBOA and related amino acids. Org Biomol Chem 2017; 15:2341-2344. [DOI: 10.1039/c7ob00305f] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Rapid route tol-TFB-TBOA: Using only nine chemical transformations, we have managed to construct the complex amino acidl-TFB-TBOA starting from commercially available dimethyl acetylenedicarboxylate.
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Affiliation(s)
- Haigen Fu
- Department of Chemical and Pharmaceutical Biology
- Groningen Research Institute of Pharmacy
- University of Groningen
- 9713 AV Groningen
- The Netherlands
| | - Sabry H. H. Younes
- Department of Chemical and Pharmaceutical Biology
- Groningen Research Institute of Pharmacy
- University of Groningen
- 9713 AV Groningen
- The Netherlands
| | - Mohammad Saifuddin
- Department of Chemical and Pharmaceutical Biology
- Groningen Research Institute of Pharmacy
- University of Groningen
- 9713 AV Groningen
- The Netherlands
| | - Pieter G. Tepper
- Department of Chemical and Pharmaceutical Biology
- Groningen Research Institute of Pharmacy
- University of Groningen
- 9713 AV Groningen
- The Netherlands
| | - Jielin Zhang
- Department of Chemical and Pharmaceutical Biology
- Groningen Research Institute of Pharmacy
- University of Groningen
- 9713 AV Groningen
- The Netherlands
| | | | | | - Wiktor Szymanski
- Department of Radiology
- University of Groningen
- University Medical Center Groningen
- 9713 GZ Groningen
- The Netherlands
| | - Gerrit J. Poelarends
- Department of Chemical and Pharmaceutical Biology
- Groningen Research Institute of Pharmacy
- University of Groningen
- 9713 AV Groningen
- The Netherlands
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22
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Hansen JC, Bjørn-Yoshimoto WE, Bisballe N, Nielsen B, Jensen AA, Bunch L. β-Sulfonamido Functionalized Aspartate Analogues as Excitatory Amino Acid Transporter Inhibitors: Distinct Subtype Selectivity Profiles Arising from Subtle Structural Differences. J Med Chem 2016; 59:8771-8786. [PMID: 27636002 DOI: 10.1021/acs.jmedchem.6b01066] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
In this study inspired by previous work on 3-substituted Asp analogues, we designed and synthesized a total of 32 β-sulfonamide Asp analogues and characterized their pharmacological properties at the excitatory amino acid transporter subtypes EAAT1, EAAT2, and EAAT3. In addition to several potent EAAT inhibitors displaying IC50 values ∼1 μM at all three subtypes, this elaborate structure-activity relationship also identified analogues exhibiting distinct preferences or selectivities for specific transporter subtypes. Introduction of two fluorine atoms on the phenyl ring yielded analogue 4y that displayed an IC50 of 0.8 μM at EAAT1 with a 14- and 9-fold preference over EAAT2 and EAAT3, respectively. Conversely, the m-CF3-phenyl analogue 4r was a potent selective EAAT2-inhibitor (IC50 = 2.8 μM) exhibiting 30- and 50-fold selectivity over EAAT1 and EAAT3, respectively. In conclusion, even small structural differences in these β-sulfonamide Asp analogues provide analogues with diverse EAAT subtype selectivity profiles.
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Affiliation(s)
- Jacob C Hansen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, Copenhagen Ø 2100, Denmark
| | - Walden E Bjørn-Yoshimoto
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, Copenhagen Ø 2100, Denmark
| | - Niels Bisballe
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, Copenhagen Ø 2100, Denmark
| | - Birgitte Nielsen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, Copenhagen Ø 2100, Denmark
| | - Anders A Jensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, Copenhagen Ø 2100, Denmark
| | - Lennart Bunch
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, Copenhagen Ø 2100, Denmark
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23
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Hansen SW, Erichsen MN, Fu B, Bjørn-Yoshimoto WE, Abrahamsen B, Hansen JC, Jensen AA, Bunch L. Identification of a New Class of Selective Excitatory Amino Acid Transporter Subtype 1 (EAAT1) Inhibitors Followed by a Structure-Activity Relationship Study. J Med Chem 2016; 59:8757-8770. [PMID: 27626828 DOI: 10.1021/acs.jmedchem.6b01058] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Screening of a small compound library at the three excitatory amino acid transporter subtypes 1-3 (EAAT1-3) resulted in the identification of compound (Z)-4-chloro-3-(5-((3-(2-ethoxy-2-oxoethyl)-2,4-dioxothiazolidin-5-ylidene)methyl)furan-2-yl)benzoic acid (1a) that exhibited a distinct preference as an inhibitor at EAAT1 (IC50 20 μM) compared to EAAT2 and EAAT3 (IC50 > 300 μM). This prompted us to subject 1a to an elaborate structure-activity relationship study through the purchase and synthesis and subsequent pharmacological characterization of a total of 36 analogues. Although this effort did not result in analogues with substantially improved inhibitory potencies at EAAT1 compared to that displayed by the hit, it provided a detailed insight into structural requirements for EAAT1 activity of this scaffold. The discovery of this new class of EAAT1-selective inhibitors not only supplements the currently available pharmacological tools in the EAAT field but also substantiates the notion that EAAT ligands not derived from α-amino acids hold considerable potential in terms of subtype-selective modulation of the transporters.
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Affiliation(s)
- Stinne W Hansen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, Copenhagen Ø 2100, Denmark
| | - Mette N Erichsen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, Copenhagen Ø 2100, Denmark
| | - Bingru Fu
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, Copenhagen Ø 2100, Denmark
| | - Walden E Bjørn-Yoshimoto
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, Copenhagen Ø 2100, Denmark
| | - Bjarke Abrahamsen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, Copenhagen Ø 2100, Denmark
| | - Jacob C Hansen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, Copenhagen Ø 2100, Denmark
| | - Anders A Jensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, Copenhagen Ø 2100, Denmark
| | - Lennart Bunch
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, Copenhagen Ø 2100, Denmark
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24
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Leuenberger M, Ritler A, Simonin A, Hediger MA, Lochner M. Concise Asymmetric Synthesis and Pharmacological Characterization of All Stereoisomers of Glutamate Transporter Inhibitor TFB-TBOA and Synthesis of EAAT Photoaffinity Probes. ACS Chem Neurosci 2016; 7:534-9. [PMID: 26918289 DOI: 10.1021/acschemneuro.5b00311] [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] [Indexed: 01/25/2023] Open
Abstract
Glutamate is the major excitatory neurotransmitter in the mammalian brain. Its rapid clearance after the release into the synaptic cleft is vital in order to avoid toxic effects and is ensured by several transmembrane transport proteins, so-called excitatory amino acid transporters (EAATs). Impairment of glutamate removal has been linked to several neurodegenerative diseases and EAATs have therefore received increased attention as therapeutic targets. O-Benzylated l-threo-β-hydroxyaspartate derivatives have been developed previously as highly potent inhibitors of EAATs with TFB-TBOA ((2S,3S)-2-amino-3-((3-(4-(trifluoromethyl)benzamido)benzyl)oxy)succinic acid) standing out as low-nanomolar inhibitor. We report the stereoselective synthesis of all four stereoisomers of TFB-TBOA in less than a fifth of synthetic steps than the published route. For the first time, the inhibitory activity and isoform selectivity of these TFB-TBOA enantio- and diastereomers were assessed on human glutamate transporters EAAT1-3. Furthermore, we synthesized potent photoaffinity probes based on TFB-TBOA using our novel synthetic strategy.
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Affiliation(s)
- Michele Leuenberger
- Department
of Chemistry and Biochemistry, University of Bern, 3012 Bern, Switzerland
- Swiss National Centre
of Competence in Research, NCCR TransCure, 3008 Bern, Switzerland
| | - Andreas Ritler
- Department
of Chemistry and Biochemistry, University of Bern, 3012 Bern, Switzerland
| | - Alexandre Simonin
- Institute
of Biochemistry and Molecular Medicine, University of Bern, 3012 Bern, Switzerland
- Swiss National Centre
of Competence in Research, NCCR TransCure, 3008 Bern, Switzerland
| | - Matthias A. Hediger
- Institute
of Biochemistry and Molecular Medicine, University of Bern, 3012 Bern, Switzerland
- Swiss National Centre
of Competence in Research, NCCR TransCure, 3008 Bern, Switzerland
| | - Martin Lochner
- Department
of Chemistry and Biochemistry, University of Bern, 3012 Bern, Switzerland
- Swiss National Centre
of Competence in Research, NCCR TransCure, 3008 Bern, Switzerland
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25
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Hansen SW, Erichsen MN, Huynh THV, Ruiz JA, Haym I, Bjørn-Yoshimoto WE, Abrahamsen B, Hansen J, Storgaard M, Eriksen AL, Jensen AA, Bunch L. New Insight into the Structure-Activity Relationships of the Selective Excitatory Amino Acid Transporter Subtype 1 (EAAT1) Inhibitors UCPH-101 and UCPH-102. ChemMedChem 2016; 11:382-402. [DOI: 10.1002/cmdc.201500525] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Indexed: 11/11/2022]
Affiliation(s)
- Stinne W. Hansen
- Department of Drug Design and Pharmacology; Faculty of Health and Medical Sciences; University of Copenhagen; 2100 Copenhagen Ø Denmark
| | - Mette N. Erichsen
- Department of Drug Design and Pharmacology; Faculty of Health and Medical Sciences; University of Copenhagen; 2100 Copenhagen Ø Denmark
| | - Tri H. V. Huynh
- Department of Drug Design and Pharmacology; Faculty of Health and Medical Sciences; University of Copenhagen; 2100 Copenhagen Ø Denmark
| | - Josep A. Ruiz
- Department of Drug Design and Pharmacology; Faculty of Health and Medical Sciences; University of Copenhagen; 2100 Copenhagen Ø Denmark
| | - Isabell Haym
- Department of Drug Design and Pharmacology; Faculty of Health and Medical Sciences; University of Copenhagen; 2100 Copenhagen Ø Denmark
| | - Walden E. Bjørn-Yoshimoto
- Department of Drug Design and Pharmacology; Faculty of Health and Medical Sciences; University of Copenhagen; 2100 Copenhagen Ø Denmark
| | - Bjarke Abrahamsen
- Department of Drug Design and Pharmacology; Faculty of Health and Medical Sciences; University of Copenhagen; 2100 Copenhagen Ø Denmark
| | - Jeanette Hansen
- Department of Drug Design and Pharmacology; Faculty of Health and Medical Sciences; University of Copenhagen; 2100 Copenhagen Ø Denmark
| | - Morten Storgaard
- Department of Drug Design and Pharmacology; Faculty of Health and Medical Sciences; University of Copenhagen; 2100 Copenhagen Ø Denmark
| | - Anette L. Eriksen
- Department of Drug Design and Pharmacology; Faculty of Health and Medical Sciences; University of Copenhagen; 2100 Copenhagen Ø Denmark
| | - Anders A. Jensen
- Department of Drug Design and Pharmacology; Faculty of Health and Medical Sciences; University of Copenhagen; 2100 Copenhagen Ø Denmark
| | - Lennart Bunch
- Department of Drug Design and Pharmacology; Faculty of Health and Medical Sciences; University of Copenhagen; 2100 Copenhagen Ø Denmark
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Takahashi K, Foster JB, Lin CLG. Glutamate transporter EAAT2: regulation, function, and potential as a therapeutic target for neurological and psychiatric disease. Cell Mol Life Sci 2015; 72:3489-506. [PMID: 26033496 PMCID: PMC11113985 DOI: 10.1007/s00018-015-1937-8] [Citation(s) in RCA: 108] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Revised: 05/22/2015] [Accepted: 05/26/2015] [Indexed: 12/12/2022]
Abstract
Glutamate is the predominant excitatory neurotransmitter in the central nervous system. Excitatory amino acid transporter 2 (EAAT2) is primarily responsible for clearance of extracellular glutamate to prevent neuronal excitotoxicity and hyperexcitability. EAAT2 plays a critical role in regulation of synaptic activity and plasticity. In addition, EAAT2 has been implicated in the pathogenesis of many central nervous system disorders. In this review, we summarize current understanding of EAAT2, including structure, pharmacology, physiology, and functions, as well as disease relevancy, such as in stroke, Parkinson's disease, epilepsy, amyotrophic lateral sclerosis, Alzheimer's disease, major depressive disorder, and addiction. A large number of studies have demonstrated that up-regulation of EAAT2 protein provides significant beneficial effects in many disease models suggesting EAAT2 activation is a promising therapeutic approach. Several EAAT2 activators have been identified. Further understanding of EAAT2 regulatory mechanisms could improve development of drug-like compounds that spatiotemporally regulate EAAT2.
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Affiliation(s)
- Kou Takahashi
- Department of Neuroscience, The Ohio State University, 333 West 10th Avenue, Columbus, OH 43210 USA
| | - Joshua B. Foster
- Department of Neuroscience, The Ohio State University, 333 West 10th Avenue, Columbus, OH 43210 USA
| | - Chien-Liang Glenn Lin
- Department of Neuroscience, The Ohio State University, 333 West 10th Avenue, Columbus, OH 43210 USA
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27
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Fontana ACK. Current approaches to enhance glutamate transporter function and expression. J Neurochem 2015; 134:982-1007. [DOI: 10.1111/jnc.13200] [Citation(s) in RCA: 105] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2015] [Revised: 05/19/2015] [Accepted: 05/20/2015] [Indexed: 12/12/2022]
Affiliation(s)
- Andréia C. K. Fontana
- Department of Pharmacology and Physiology; Drexel University College of Medicine; Philadelphia Pennsylvania USA
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28
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Medrano MC, Mendiguren A, Pineda J. Effect of ceftriaxone and topiramate treatments on naltrexone-precipitated morphine withdrawal and glutamate receptor desensitization in the rat locus coeruleus. Psychopharmacology (Berl) 2015; 232:2795-809. [PMID: 25787747 DOI: 10.1007/s00213-015-3913-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2014] [Accepted: 03/08/2015] [Indexed: 12/22/2022]
Abstract
RATIONALE Morphine withdrawal is associated with a hyperactivity of locus coeruleus (LC) neurons by an elevated glutamate neurotransmission in this nucleus. We postulate that reductions in the amount of glutamate in the LC by enhancing its reuptake or inhibiting its release could attenuate the behavioral and cellular consequences of morphine withdrawal. OBJECTIVES We investigated the effect of chronic treatment with ceftriaxone (CFT), an excitatory amino acid transporter (EAAT2) enhancer, and acute administration of topiramate (TPM), a glutamate release inhibitor, on morphine withdrawal syndrome and withdrawal-induced glutamate receptor (GluR) desensitization in LC neurons from morphine-dependent rats. METHODS Morphine withdrawal behavior was measured after naltrexone administration in rats implanted with a morphine (200 mg kg(-1)) emulsion for 3 days. GluR desensitization in the LC was assessed by performing concentration-effect curves for glutamate by extracellular electrophysiological recordings in vitro. RESULTS Treatments with CFT or TPM reduced, in a dose-related manner, the total behavioral score of naltrexone-precipitated morphine withdrawal. CFT and TPM, at doses that were effective in behavioral tests, also reduced the induction of GluR desensitization normally occurring in LC neurons from morphine-dependent rats. Acute treatment with the specific EAAT2 inhibitor dihydrokainic acid (DHK) prevented the effect of CFT on withdrawal syndrome and GluR desensitization. Perfusion with TPM inhibited KCl-evoked but not glutamate-induced activation of LC neurons in vitro. CONCLUSIONS Our results suggest that a reduction of synaptic concentrations of glutamate by enhancing EAAT2-mediated uptake or inhibiting glutamate release alleviates the behavioral response and the cellular changes in the LC during opiate withdrawal.
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Affiliation(s)
- María Carmen Medrano
- Department of Pharmacology, Faculty of Medicine and Odontology, University of the Basque Country (UPV/EHU), B° Sarriena s/n, 48940, Leioa, Bizkaia, Spain
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29
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de Villiers J, de Villiers M, Geertsema EM, Raj H, Poelarends GJ. Chemoenzymatic Synthesis of ortho-, meta-, and para-Substituted Derivatives of l- threo-3-Benzyloxyaspartate, An Important Glutamate Transporter Blocker. ChemCatChem 2015; 7:1931-1934. [PMID: 26251674 PMCID: PMC4517298 DOI: 10.1002/cctc.201500318] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Indexed: 01/13/2023]
Abstract
A simple, three-step chemoenzymatic synthesis of l-threo-3-benzyloxyaspartate (l-TBOA), as well as l-TBOA derivatives with F, CF3, and CH3 substituents at the aromatic ring, starting from dimethyl acetylenedicarboxylate was investigated. These chiral amino acids, which are extremely difficult to prepare by chemical synthesis, form an important class of inhibitors of excitatory amino acid transporters involved in the regulation of glutamatergic neurotransmission. In addition, a new chemical procedure for the synthesis of racemic mixtures of TBOA and its derivatives was explored. These chemically prepared racemates are valuable reference compounds in chiral-phase HPLC to establish the enantiopurities of the corresponding chemoenzymatically prepared amino acids.
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Affiliation(s)
- Jandré de Villiers
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen (The Netherlands )
| | - Marianne de Villiers
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen (The Netherlands )
| | - Edzard M Geertsema
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen (The Netherlands )
| | - Hans Raj
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen (The Netherlands ) ; Current address: Chr-Hansen A/S, Boge Alle 10-12 2970 Horsholm (Denmark)
| | - Gerrit J Poelarends
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen (The Netherlands )
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30
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Lantz SR, Mack CM, Wallace K, Key EF, Shafer TJ, Casida JE. Glufosinate binds N-methyl-d-aspartate receptors and increases neuronal network activity in vitro. Neurotoxicology 2014; 45:38-47. [DOI: 10.1016/j.neuro.2014.09.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 09/17/2014] [Accepted: 09/19/2014] [Indexed: 11/28/2022]
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31
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Gudiño-Cabrera G, Ureña-Guerrero ME, Rivera-Cervantes MC, Feria-Velasco AI, Beas-Zárate C. Excitotoxicity triggered by neonatal monosodium glutamate treatment and blood-brain barrier function. Arch Med Res 2014; 45:653-9. [PMID: 25431840 DOI: 10.1016/j.arcmed.2014.11.014] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 11/13/2014] [Indexed: 12/21/2022]
Abstract
It is likely that monosodium glutamate (MSG) is the excitotoxin that has been most commonly employed to characterize the process of excitotoxicity and to improve understanding of the ways that this process is related to several pathological conditions of the central nervous system. Excitotoxicity triggered by neonatal MSG treatment produces a significant pathophysiological impact on adulthood, which could be due to modifications in the blood-brain barrier (BBB) permeability and vice versa. This mini-review analyzes this topic through brief descriptions about excitotoxicity, BBB structure and function, role of the BBB in the regulation of Glu extracellular levels, conditions that promote breakdown of the BBB, and modifications induced by neonatal MSG treatment that could alter the behavior of the BBB. In conclusion, additional studies to better characterize the effects of neonatal MSG treatment on excitatory amino acids transporters, ionic exchangers, and efflux transporters, as well as the role of the signaling pathways mediated by erythropoietin and vascular endothelial growth factor in the cellular elements of the BBB, should be performed to identify the mechanisms underlying the increase in neurovascular permeability associated with excitotoxicity observed in several diseases and studied using neonatal MSG treatment.
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Affiliation(s)
- Graciela Gudiño-Cabrera
- Departamento de Biología Celular y Molecular, Centro Universitario de Ciencias Biológicas y Agropecuarias, Universidad de Guadalajara, Zapopan, Jalisco, México
| | - Monica E Ureña-Guerrero
- Departamento de Biología Celular y Molecular, Centro Universitario de Ciencias Biológicas y Agropecuarias, Universidad de Guadalajara, Zapopan, Jalisco, México
| | - Martha C Rivera-Cervantes
- Departamento de Biología Celular y Molecular, Centro Universitario de Ciencias Biológicas y Agropecuarias, Universidad de Guadalajara, Zapopan, Jalisco, México
| | - Alfredo I Feria-Velasco
- Departamento de Biología Celular y Molecular, Centro Universitario de Ciencias Biológicas y Agropecuarias, Universidad de Guadalajara, Zapopan, Jalisco, México
| | - Carlos Beas-Zárate
- Departamento de Biología Celular y Molecular, Centro Universitario de Ciencias Biológicas y Agropecuarias, Universidad de Guadalajara, Zapopan, Jalisco, México; División de Neurociencias, CIBO, IMSS, Guadalajara, Jalisco, México.
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32
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Jensen AA, Fahlke C, Bjørn-Yoshimoto WE, Bunch L. Excitatory amino acid transporters: recent insights into molecular mechanisms, novel modes of modulation and new therapeutic possibilities. Curr Opin Pharmacol 2014; 20:116-23. [PMID: 25466154 DOI: 10.1016/j.coph.2014.10.008] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2014] [Revised: 10/05/2014] [Accepted: 10/21/2014] [Indexed: 11/24/2022]
Abstract
The five excitatory amino acid transporters (EAAT1-5) mediating the synaptic uptake of the major excitatory neurotransmitter glutamate are differently expressed throughout the CNS and at the synaptic level. Although EAATs are crucial for normal excitatory neurotransmission, explorations into the physiological functions mediated by the different transporter subtypes and their respective therapeutic potential have so far been sparse, in no small part due to the limited selection of pharmacological tools available. In the present update, we outline important new insights into the molecular compositions of EAATs and their intricate transport process, the novel approaches to pharmacological modulation of the transporters that have emerged, and interesting new perspectives in EAAT as drug targets proposed in recent years.
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Affiliation(s)
- Anders A Jensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2100 Copenhagen OE, Denmark.
| | - Christoph Fahlke
- Institute of Complex Systems, Zelluläre Biophysik (ICS-4), Forschungszentrum Jülich, Germany
| | - Walden E Bjørn-Yoshimoto
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2100 Copenhagen OE, Denmark
| | - Lennart Bunch
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2100 Copenhagen OE, Denmark
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33
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Sun P, Zhang S, Li Y, Wang L. Harmine mediated neuroprotection via evaluation of glutamate transporter 1 in a rat model of global cerebral ischemia. Neurosci Lett 2014; 583:32-6. [DOI: 10.1016/j.neulet.2014.09.023] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Revised: 09/05/2014] [Accepted: 09/07/2014] [Indexed: 01/17/2023]
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34
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Gegelashvili G, Bjerrum OJ. High-affinity glutamate transporters in chronic pain: an emerging therapeutic target. J Neurochem 2014; 131:712-30. [DOI: 10.1111/jnc.12957] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Revised: 09/18/2014] [Accepted: 09/25/2014] [Indexed: 01/13/2023]
Affiliation(s)
- Georgi Gegelashvili
- Department of Drug Design and Pharmacology; Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
- Institute of Chemical Biology; Ilia State University; Tbilisi Georgia
| | - Ole J. Bjerrum
- Department of Drug Design and Pharmacology; Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
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35
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Ding Y, Zhang K, Liu S, Zhang Q, Ma C, Bruce IC, Zhang X. Tumor necrosis factor-α promotes the expression of excitatory amino-acid transporter 2 in astrocytes: Optimal concentration and incubation time. Exp Ther Med 2014; 8:1909-1913. [PMID: 25371754 PMCID: PMC4217772 DOI: 10.3892/etm.2014.2024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Accepted: 09/08/2014] [Indexed: 12/16/2022] Open
Abstract
The aim of the present study was to determine whether tumor necrosis factor (TNF)-α regulates the expression levels of excitatory amino-acid transporters (EAATs) in primary astrocytes and its roles in brain ischemia. Exogenous TNF-α was administered to pure cultured astrocytes and the expression levels of EAAT1, EAAT2 and glial fibrillary acidic protein (GFAP) were evaluated. The results showed that TNF-α at 10 ng/ml enhanced the expression of EAAT2 in a time-dependent manner, while the expression levels of EAAT1 and GFAP did not change. To determine whether the elevation in the levels of the EAAT2 protein induced by TNF-α had a beneficial effect on ischemic insult, TNF-α was applied to in vitro models of cerebral ischemia; the treatment was observed to increase neuronal viability. The present results suggest that a relatively short-term application of an optimal concentration of TNF-α may protect neurons against ischemic injury by elevating the expression of EAAT2 in astrocytes.
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Affiliation(s)
- Yuemin Ding
- School of Medicine, Zhejiang University City College, Hangzhou, Zhejiang 310015, P.R. China ; Department of Basic Medicine, College of Medicine, Zhejiang University, Hangzhou, Zhejiang 310058, P.R. China
| | - Kena Zhang
- College of Basic Medical Science, Zhejiang Chinese Medical University, Hangzhou, Zhejiang 310053, P.R. China
| | - Shuqin Liu
- Department of Pharmacy, Wannan Medical College, Wuhu, Anhui 241002, P.R. China
| | - Qijun Zhang
- Department of Basic Medicine, College of Medicine, Zhejiang University, Hangzhou, Zhejiang 310058, P.R. China
| | - Chiyuan Ma
- Department of Basic Medicine, College of Medicine, Zhejiang University, Hangzhou, Zhejiang 310058, P.R. China
| | - Iain C Bruce
- Department of Basic Medicine, College of Medicine, Zhejiang University, Hangzhou, Zhejiang 310058, P.R. China
| | - Xiong Zhang
- Department of Basic Medicine, College of Medicine, Zhejiang University, Hangzhou, Zhejiang 310058, P.R. China
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36
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Karki P, Smith K, Johnson J, Aschner M, Lee E. Role of transcription factor yin yang 1 in manganese-induced reduction of astrocytic glutamate transporters: Putative mechanism for manganese-induced neurotoxicity. Neurochem Int 2014; 88:53-9. [PMID: 25128239 DOI: 10.1016/j.neuint.2014.08.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Revised: 07/31/2014] [Accepted: 08/05/2014] [Indexed: 10/24/2022]
Abstract
Astrocytes are the most abundant non-neuronal glial cells in the brain. Once relegated to a mere supportive role for neurons, contemporary dogmas ascribe multiple active roles for these cells in central nervous system (CNS) function, including maintenance of optimal glutamate levels in synapses. Regulation of glutamate levels in the synaptic cleft is crucial for preventing excitotoxic neuronal injury. Glutamate levels are regulated predominantly by two astrocytic glutamate transporters, glutamate transporter 1 (GLT-1) and glutamate aspartate transporter (GLAST). Indeed, the dysregulation of these transporters has been linked to several neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS), Alzheimer's disease (AD) and Parkinson's disease (PD), as well as manganism, which is caused by overexposure to the trace metal, manganese (Mn). Although Mn is an essential trace element, its excessive accumulation in the brain as a result of chronic occupational or environmental exposures induces a neurological disorder referred to as manganism, which shares common pathological features with Parkinsonism. Mn decreases the expression and function of both GLAST and GLT-1. Astrocytes are commonly targeted by Mn, and thus reduction in astrocytic glutamate transporter function represents a critical mechanism of Mn-induced neurotoxicity. In this review, we will discuss the role of astrocytic glutamate transporters in neurodegenerative diseases and Mn-induced neurotoxicity.
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Affiliation(s)
- Pratap Karki
- Department of Physiology, Meharry Medical College, Nashville, TN 37208, United States
| | - Keisha Smith
- Department of Physiology, Meharry Medical College, Nashville, TN 37208, United States
| | - James Johnson
- Department of Physiology, Meharry Medical College, Nashville, TN 37208, United States
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461, United States
| | - Eunsook Lee
- Department of Physiology, Meharry Medical College, Nashville, TN 37208, United States.
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Rapoport SI. Lithium and the other mood stabilizers effective in bipolar disorder target the rat brain arachidonic acid cascade. ACS Chem Neurosci 2014; 5:459-67. [PMID: 24786695 DOI: 10.1021/cn500058v] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
This Review evaluates the arachidonic acid (AA, 20:4n-6) cascade hypothesis for the actions of lithium and other FDA-approved mood stabilizers in bipolar disorder (BD). The hypothesis is based on evidence in unanesthetized rats that chronically administered lithium, carbamazepine, valproate, or lamotrigine each downregulated brain AA metabolism, and it is consistent with reported upregulated AA cascade markers in post-mortem BD brain. In the rats, each mood stabilizer reduced AA turnover in brain phospholipids, cyclooxygenase-2 expression, and prostaglandin E2 concentration. Lithium and carbamazepine also reduced expression of cytosolic phospholipase A2 (cPLA2) IVA, which releases AA from membrane phospholipids, whereas valproate uncompetitively inhibited in vitro acyl-CoA synthetase-4, which recycles AA into phospholipid. Topiramate and gabapentin, proven ineffective in BD, changed rat brain AA metabolism minimally. On the other hand, the atypical antipsychotics olanzapine and clozapine, which show efficacy in BD, decreased rat brain AA metabolism by reducing plasma AA availability. Each of the four approved mood stabilizers also dampened brain AA signaling during glutamatergic NMDA and dopaminergic D2 receptor activation, while lithium enhanced the signal during cholinergic muscarinic receptor activation. In BD patients, such signaling effects might normalize the neurotransmission imbalance proposed to cause disease symptoms. Additionally, the antidepressants fluoxetine and imipramine, which tend to switch BD depression to mania, each increased AA turnover and cPLA2 IVA expression in rat brain, suggesting that brain AA metabolism is higher in BD mania than depression. The AA hypothesis for mood stabilizer action is consistent with reports that low-dose aspirin reduced morbidity in patients taking lithium, and that high n-3 and/or low n-6 polyunsaturated fatty acid diets, which in rats reduce brain AA metabolism, were effective in BD and migraine patients.
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Affiliation(s)
- Stanley I. Rapoport
- Brain Physiology and Metabolism Section, Laboratory of Neurosciences, National Institute on Aging, National Institutes of Health, Bethesda, Maryland 20892, United States
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38
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Probing for Improved Potency and In Vivo Bioavailability of Excitatory Amino Acid Transporter Subtype 1 Inhibitors UCPH-101 and UCPH-102: Design, Synthesis and Pharmacological Evaluation of Substituted 7-Biphenyl Analogs. Neurochem Res 2014; 39:1964-79. [DOI: 10.1007/s11064-014-1264-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 02/19/2014] [Accepted: 02/20/2014] [Indexed: 02/02/2023]
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39
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Medrano MC, Gerrikagoitia I, Martínez-Millán L, Mendiguren A, Pineda J. Functional and morphological characterization of glutamate transporters in the rat locus coeruleus. Br J Pharmacol 2014; 169:1781-94. [PMID: 23638698 DOI: 10.1111/bph.12235] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Revised: 04/19/2013] [Accepted: 04/29/2013] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND AND PURPOSE Excitatory amino acid transporters (EAATs) in the CNS contribute to the clearance of glutamate released during neurotransmission. The aim of this study was to explore the role of EAATs in the regulation of locus coeruleus (LC) neurons by glutamate. EXPERIMENTAL APPROACH We measured the effect of different EAAT subtype inhibitors/enhancers on glutamate- and KCl-induced activation of LC neurons in rat slices. EAAT2-3 expression in the LC was also characterized by immunohistochemistry. KEY RESULTS The EAAT2-5 inhibitor DL-threo-β-benzyloxaspartic acid (100 μM), but not the EAAT2, 4, 5 inhibitor L-trans-pyrrolidine-2,4-dicarboxylic acid (100 μM) or the EAAT2 inhibitor dihydrokainic acid (DHK; 100 μM), enhanced the glutamate- and KCl-induced activation of the firing rate of LC neurons. These effects were blocked by ionotropic, but not metabotrobic, glutamate receptor antagonists. DHK (100 μM) was the only EAAT inhibitor that increased the spontaneous firing rate of LC cells, an effect that was due to inhibition of EAAT2 and subsequent AMPA receptor activation. Chronic treatment with ceftriaxone (200 mg·kg(-1) i.p., once daily, 7 days), an EAAT2 expression enhancer, increased the actions of glutamate and DHK, suggesting a functional impact of EAAT2 up-regulation on the glutamatergic system. Immuhistochemical data revealed the presence of EAAT2 and EAAT3 surrounding noradrenergic neurons and EAAT2 on glial cells in the LC. CONCLUSIONS AND IMPLICATIONS These results remark the importance of EAAT2 and EAAT3 in the regulation of rat LC by glutamate. Neuronal EAAT3 would be responsible for terminating the action of synaptically released glutamate, whereas glial EAAT2 would regulate tonic glutamate concentrations in this nucleus.
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Affiliation(s)
- M C Medrano
- Department of Pharmacology, Faculty of Medicine and Odontology, University of the Basque Country (UPV/ EHU), Bizkaia, Spain
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40
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Torrente D, Cabezas R, Avila MF, García-Segura LM, Barreto GE, Guedes RCA. Cortical spreading depression in traumatic brain injuries: is there a role for astrocytes? Neurosci Lett 2014; 565:2-6. [PMID: 24394907 DOI: 10.1016/j.neulet.2013.12.058] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Revised: 12/21/2013] [Accepted: 12/23/2013] [Indexed: 10/25/2022]
Abstract
Cortical spreading depression (CSD) is a presumably pathophysiological phenomenon that interrupts local cortical function for periods of minutes to hours. This phenomenon is important due to its association with different neurological disorders such as migraine, malignant stroke and traumatic brain injury (TBI). Glial cells, especially astrocytes, play an important role in the regulation of CSD and in the protection of neurons under brain trauma. The correlation of TBI with CSD and the astrocytic function under these conditions remain unclear. This review discusses the possible link of TBI and CSD and its implication for neuronal survival. Additionally, we highlight the importance of astrocytic function for brain protection, and suggest possible therapeutic strategies targeting astrocytes to improve the outcome following TBI-associated CSD.
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Affiliation(s)
- Daniel Torrente
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá D.C., Colombia
| | - Ricardo Cabezas
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá D.C., Colombia
| | - Marco Fidel Avila
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá D.C., Colombia
| | | | - George E Barreto
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá D.C., Colombia
| | - Rubem Carlos Araújo Guedes
- Departamento de Nutrição, Centro de Ciências da Saúde, Universidade Federal de Pernambuco, Recife, PE, Brazil.
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41
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Huynh THV, Demmer CS, Abrahamsen B, Marcher E, Frykman M, Jensen AA, Bunch L. Structure-activity-relationship study of N-acyl-N-phenylpiperazines as potential inhibitors of the Excitatory Amino Acid Transporters (EAATs): improving the potency of a micromolar screening Hit is not truism. SPRINGERPLUS 2013; 2:112. [PMID: 25530930 PMCID: PMC4225009 DOI: 10.1186/2193-1801-2-112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Accepted: 02/28/2013] [Indexed: 11/10/2022]
Abstract
Abstract
The excitatory amino acid transporters (EAATs) are transmembrane proteins responsible for the uptake of (S)-glutamate from the synaptic cleft. To date, five subtypes EAAT1-5 have been identified for which selective inhibitors have been discovered for EAAT1 and EAAT2. By screening of a commercially available compound library consisting of 4,000 compounds, N-acyl-N-phenylpiperazine analog (±)-
exo
-1 was identified to be a non-selective inhibitor at EAAT1-3 displaying IC50 values in the mid-micromolar range (10 μ M, 40 μ M and 30 μ M at EAAT1, 2 and 3, respectively). Subsequently, we designed and synthesized a series of analogs to explore the structure-activity-relationship of this scaffold in the search for analogs characterized by increased inhibitory potency and/or EAAT subtype selectivity. Despite extensive efforts, all analogs of (±)-
exo
-1 proved to be either inactive or to have least 3-fold lower inhibitory potency than the lead, and furthermore none of the active analogs displayed selectivity for a particular subtype amongst the EAAT1-3. On the basis of our findings, we speculate that (±)-
exo
-1 binds to a recess (deepening) on the EAAT proteins than a well-defined pocket.
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42
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Poletti S, Radaelli D, Bosia M, Buonocore M, Pirovano A, Lorenzi C, Cavallaro R, Smeraldi E, Benedetti F. Effect of glutamate transporter EAAT2 gene variants and gray matter deficits on working memory in schizophrenia. Eur Psychiatry 2013; 29:219-25. [PMID: 24076156 DOI: 10.1016/j.eurpsy.2013.07.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Revised: 07/17/2013] [Accepted: 07/27/2013] [Indexed: 01/04/2023] Open
Abstract
Glutamate is the major excitatory neurotransmitter in the brain, with up to 40% of all synapses being glutamatergic. An altered glutamatergic transmission could play a critical role in working memory deficts observed in schizophrenia and could underline progressive changes such as grey matter loss throughout the brain. The aim of the study was to investigate if gray matter volume and working memory could be modulated by a genetic polymorphism related to glutamatergic function. Fifty schizophrenia patients underwent magnetic resonance and working memory testing outside of the scanner and were genotyped for rs4354668 EAAT2 polymorphism. Carriers of the G allele had lower gray matter volumes than T/T homozygote and worse working memory performance. Poor working memory performance was associated with gray matter reduction. Differences between the three genotypes are more relevant among patients showing poor performance at the 2-back task. Since glutamate abnormalities are known to be involved in excitotoxic processes, the decrease in cortical thickness observed in schizophrenia patients could be linked to an excess of extracellular glutamate. The differential effect of EAAT2 observed between good and poor performers suggests that the effect of EEAT2 on gray matter might reveal in the presence of a pathological process affecting gray matter.
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Affiliation(s)
- S Poletti
- Department of Clinical Neurosciences, Scientific Institute and University Vita-Salute San Raffaele, Milan, Italy; Centro di Eccellenza Risonanza Magnetica ad Alto Campo (CERMAC), University Vita-Salute San Raffaele, Milan, Italy.
| | - D Radaelli
- Department of Clinical Neurosciences, Scientific Institute and University Vita-Salute San Raffaele, Milan, Italy; Centro di Eccellenza Risonanza Magnetica ad Alto Campo (CERMAC), University Vita-Salute San Raffaele, Milan, Italy
| | - M Bosia
- Department of Clinical Neurosciences, Scientific Institute and University Vita-Salute San Raffaele, Milan, Italy
| | - M Buonocore
- Department of Clinical Neurosciences, Scientific Institute and University Vita-Salute San Raffaele, Milan, Italy
| | - A Pirovano
- Department of Clinical Neurosciences, Scientific Institute and University Vita-Salute San Raffaele, Milan, Italy
| | - C Lorenzi
- Department of Clinical Neurosciences, Scientific Institute and University Vita-Salute San Raffaele, Milan, Italy
| | - R Cavallaro
- Department of Clinical Neurosciences, Scientific Institute and University Vita-Salute San Raffaele, Milan, Italy
| | - E Smeraldi
- Department of Clinical Neurosciences, Scientific Institute and University Vita-Salute San Raffaele, Milan, Italy; Centro di Eccellenza Risonanza Magnetica ad Alto Campo (CERMAC), University Vita-Salute San Raffaele, Milan, Italy
| | - F Benedetti
- Department of Clinical Neurosciences, Scientific Institute and University Vita-Salute San Raffaele, Milan, Italy; Centro di Eccellenza Risonanza Magnetica ad Alto Campo (CERMAC), University Vita-Salute San Raffaele, Milan, Italy
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43
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Kanai Y, Clémençon B, Simonin A, Leuenberger M, Lochner M, Weisstanner M, Hediger MA. The SLC1 high-affinity glutamate and neutral amino acid transporter family. Mol Aspects Med 2013; 34:108-20. [PMID: 23506861 DOI: 10.1016/j.mam.2013.01.001] [Citation(s) in RCA: 216] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Accepted: 12/14/2012] [Indexed: 01/07/2023]
Abstract
Glutamate transporters play important roles in the termination of excitatory neurotransmission and in providing cells throughout the body with glutamate for metabolic purposes. The high-affinity glutamate transporters EAAC1 (SLC1A1), GLT1 (SLC1A2), GLAST (SLC1A3), EAAT4 (SLC1A6), and EAAT5 (SLC1A7) mediate the cellular uptake of glutamate by the co-transport of three sodium ions (Na(+)) and one proton (H(+)), with the counter-transport of one potassium ion (K(+)). Thereby, they protect the CNS from glutamate-induced neurotoxicity. Loss of function of glutamate transporters has been implicated in the pathogenesis of several diseases, including amyotrophic lateral sclerosis and Alzheimer's disease. In addition, glutamate transporters play a role in glutamate excitotoxicity following an ischemic stroke, due to reversed glutamate transport. Besides glutamate transporters, the SLC1 family encompasses two transporters of neutral amino acids, ASCT1 (SLC1A4) and ASCT2 (SLC1A5). Both transporters facilitate electroneutral exchange of amino acids in neurons and/or cells of the peripheral tissues. Some years ago, a high resolution structure of an archaeal homologue of the SLC1 family was determined, followed by the elucidation of its structure in the presence of the substrate aspartate and the inhibitor d,l-threo-benzyloxy aspartate (d,l-TBOA). Historically, the first few known inhibitors of SLC1 transporters were based on constrained glutamate analogs which were active in the high micromolar range but often also showed off-target activity at glutamate receptors. Further development led to the discovery of l-threo-β-hydroxyaspartate derivatives, some of which effectively inhibited SLC1 transporters at nanomolar concentrations. More recently, small molecule inhibitors have been identified whose structures are not based on amino acids. Activators of SLC1 family members have also been discovered but there are only a few examples known.
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Affiliation(s)
- Yoshikatsu Kanai
- Division of Biosystem Pharmacology, Department of Pharmacology, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565 0871, Japan
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44
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The glutamate aspartate transporter (GLAST) mediates L-glutamate-stimulated ascorbate-release via swelling-activated anion channels in cultured neonatal rodent astrocytes. Cell Biochem Biophys 2013; 65:107-19. [PMID: 22886112 DOI: 10.1007/s12013-012-9404-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Vitamin C (ascorbate) plays important neuroprotective and neuromodulatory roles in the mammalian brain. Astrocytes are crucially involved in brain ascorbate homeostasis and may assist in regenerating extracellular ascorbate from its oxidised forms. Ascorbate accumulated by astrocytes can be released rapidly by a process that is stimulated by the excitatory amino acid, L-glutamate. This process is thought to be neuroprotective against excitotoxicity. Although of potential clinical interest, the mechanism of this stimulated ascorbate-release remains unknown. Here, we report that primary cultures of mouse and rat astrocytes release ascorbate following initial uptake of dehydroascorbate and accumulation of intracellular ascorbate. Ascorbate-release was not due to cellular lysis, as assessed by cellular release of the cytosolic enzyme lactate dehydrogenase, and was stimulated by L-glutamate and L-aspartate, but not the non-excitatory amino acid L-glutamine. This stimulation was due to glutamate-induced cellular swelling, as it was both attenuated by hypertonic and emulated by hypotonic media. Glutamate-stimulated ascorbate-release was also sensitive to inhibitors of volume-sensitive anion channels, suggesting that the latter may provide the conduit for ascorbate efflux. Glutamate-stimulated ascorbate-release was not recapitulated by selective agonists of either ionotropic or group I metabotropic glutamate receptors, but was completely blocked by either of two compounds, TFB-TBOA and UCPH-101, which non-selectively and selectively inhibit the glial Na(+)-dependent excitatory amino acid transporter, GLAST, respectively. These results suggest that an impairment of astrocytic ascorbate-release may exacerbate neuronal dysfunction in neurodegenerative disorders and acute brain injury in which excitotoxicity and/or GLAST deregulation have been implicated.
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45
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Goyal RK, Chaudhury A. Structure activity relationship of synaptic and junctional neurotransmission. Auton Neurosci 2013; 176:11-31. [PMID: 23535140 PMCID: PMC3677731 DOI: 10.1016/j.autneu.2013.02.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2009] [Revised: 12/28/2012] [Accepted: 02/18/2013] [Indexed: 12/18/2022]
Abstract
Chemical neurotransmission may include transmission to local or remote sites. Locally, contact between 'bare' portions of the bulbous nerve terminal termed a varicosity and the effector cell may be in the form of either synapse or non-synaptic contact. Traditionally, all local transmissions between nerves and effector cells are considered synaptic in nature. This is particularly true for communication between neurons. However, communication between nerves and other effectors such as smooth muscles has been described as nonsynaptic or junctional in nature. Nonsynaptic neurotransmission is now also increasingly recognized in the CNS. This review focuses on the relationship between structure and function that orchestrate synaptic and junctional neurotransmissions. A synapse is a specialized focal contact between the presynaptic active zone capable of ultrafast release of soluble transmitters and the postsynaptic density that cluster ionotropic receptors. The presynaptic and the postsynaptic areas are separated by the 'closed' synaptic cavity. The physiological hallmark of the synapse is ultrafast postsynaptic potentials lasting milliseconds. In contrast, junctions are juxtapositions of nerve terminals and the effector cells without clear synaptic specializations and the junctional space is 'open' to the extracellular space. Based on the nature of the transmitters, postjunctional receptors and their separation from the release sites, the junctions can be divided into 'close' and 'wide' junctions. Functionally, the 'close' and the 'wide' junctions can be distinguished by postjunctional potentials lasting ~1s and tens of seconds, respectively. Both synaptic and junctional communications are common between neurons; however, junctional transmission is the rule at many neuro-non-neural effectors.
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Affiliation(s)
- Raj K Goyal
- Center for Swallowing and Motility Disorders, GI Division, VA Boston Healthcare System and Harvard Medical School, Boston, USA.
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46
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Allosteric modulation of an excitatory amino acid transporter: the subtype-selective inhibitor UCPH-101 exerts sustained inhibition of EAAT1 through an intramonomeric site in the trimerization domain. J Neurosci 2013; 33:1068-87. [PMID: 23325245 DOI: 10.1523/jneurosci.3396-12.2013] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
In the present study, the mechanism of action and molecular basis for the activity of the first class of selective inhibitors of the human excitatory amino acid transporter subtype 1 (EAAT1) and its rodent ortholog GLAST are elucidated. The previously reported specificity of UCPH-101 and UCPH-102 for EAAT1 over EAAT2 and EAAT3 is demonstrated to extend to the EAAT4 and EAAT5 subtypes as well. Interestingly, brief exposure to UCPH-101 induces a long-lasting inactive state of EAAT1, whereas the inhibition exerted by closely related analogs is substantially more reversible in nature. In agreement with this, the kinetic properties of UCPH-101 unblocking of the transporter are considerably slower than those of UCPH-102. UCPH-101 exhibits noncompetitive inhibition of EAAT1, and its binding site in GLAST has been delineated in an elaborate mutagenesis study. Substitutions of several residues in TM3, TM4c, and TM7a of GLAST have detrimental effects on the inhibitory potency and/or efficacy of UCPH-101 while not affecting the pharmacological properties of (S)-glutamate or the competitive EAAT inhibitor TBOA significantly. Hence, UCPH-101 is proposed to target a predominantly hydrophobic crevice in the "trimerization domain" of the GLAST monomer, and the inhibitor is demonstrated to inhibit the uptake through the monomer that it binds to exclusively and not to affect substrate translocation through the other monomers in the GLAST trimer. The allosteric mode of UCPH-101 inhibition underlines the functional importance of the trimerization domain of the EAAT and demonstrates the feasibility of modulating transporter function through ligand binding to regions distant from its "transport domain."
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47
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Dallaspezia S, Poletti S, Lorenzi C, Pirovano A, Colombo C, Benedetti F. Influence of an interaction between lithium salts and a functional polymorphism in SLC1A2 on the history of illness in bipolar disorder. Mol Diagn Ther 2013; 16:303-9. [PMID: 23023733 DOI: 10.1007/s40291-012-0004-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND Bipolar disorder (BD) is a recurrent and disabling illness, characterized by periods of depression and mania. The history of the illness differs widely between patients, with episode frequency emerging as a strong predictor of poor illness outcome. Lithium salts are the first-choice long-term mood-stabilizing therapy, but not all patients respond equally to the treatment. Evidence suggests that alterations in glutamatergic systems may contribute to the pathophysiology of depression. Moreover, glutamate signaling is involved in brain development and synaptic plasticity, both of which are modified in individuals affected by BD, and has been implicated in the etiology of the disorder. The inactivation of glutamate is handled by a series of molecular glutamate transporters (excitatory amino acid transporters [EAATs]), among which EAAT2/SLC1A2 is responsible for up to 95% of extracellular glutamate clearance. A functional single-nucleotide polymorphism at -181 bp from the transcription start site of the SLC1A2 gene has been described. This T-to-G (DNA forward strand) polymorphism, commonly known as SLC1A2 -181A>C, affects transporter expression, with the variant G allele inducing a 30% reduction in promoter activity compared with the T allele. OBJECTIVE The aims of the study were to investigate if factors affecting glutamate function, such as SLC1A2 -181A>C (rs4354668), could affect recurrence of illness in BD, and if they interact with lithium salt treatment. METHODS We performed an observational study in our university hospital in Milan. We enrolled 110 subjects (76 females, 34 males) affected by BD type I. The exclusion criteria were other diagnoses on Axis I, mental retardation on Axis II, a history of epilepsy, and major medical and neurologic disorders. Fifty-four patients had been treated with lithium salts for more than 6 months. Patients were genotyped for SLC1A2 -181A>C by polymerase chain reaction-restriction fragment length polymorphism, and the influence of genotype on BD episode recurrence rates, and the interaction between the single nucleotide polymorphism and lithium treatment, were analyzed. RESULTS The SLC1A2 -181A>C genotype significantly influenced the total recurrence of episodes, with T/T homozygotes showing a significantly lower frequency of episodes (F = 3.26; p = 0.042), and an interaction between lithium treatment and genotype (F = 3.77; p = 0.026) was found to influence the history of the illness. CONCLUSION According to our results, the glutamatergic system could be hypothesized to exert some influence on the history of illness in BD. The SLC1A2 functional polymorphism was shown to significantly influence the total episode recurrence rate, with wild-type T homozygotes presenting the lowest number of episodes, G homozygotes reporting the highest number, and heterozygotes showing an intermediate phenotype. We confirmed the efficacy of lithium treatment in reducing the recurrence of illness in BD, and we found an interaction between lithium treatment and the SLC1A2 -181A>C genotype, confirming previous studies reporting an interaction between lithium salts and the glutamatergic system.
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Affiliation(s)
- Sara Dallaspezia
- Department of Clinical Neurosciences, Istituto Scientifico Ospedale San Raffaele, San Raffaele Turro, Milan, Italy.
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48
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Assaf Z, Larsen AP, Venskutonytė R, Han L, Abrahamsen B, Nielsen B, Gajhede M, Kastrup JS, Jensen AA, Pickering DS, Frydenvang K, Gefflaut T, Bunch L. Chemoenzymatic synthesis of new 2,4-syn-functionalized (S)-glutamate analogues and structure-activity relationship studies at ionotropic glutamate receptors and excitatory amino acid transporters. J Med Chem 2013; 56:1614-28. [PMID: 23414088 DOI: 10.1021/jm301433m] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In the mammalian central nervous system, (S)-glutamate (Glu) is released from the presynaptic neuron where it activates a plethora of pre- and postsynaptic Glu receptors. The fast acting ionotropic Glu receptors (iGluRs) are ligand gated ion channels and are believed to be involved in a vast number of neurological functions such as memory and learning, synaptic plasticity, and motor function. The synthesis of 14 enantiopure 2,4-syn-Glu analogues 2b-p is accessed by a short and efficient chemoenzymatic approach starting from readily available cyclohexanone 3. Pharmacological characterization at the iGluRs and EAAT1-3 subtypes revealed analogue 2i as a selective GluK1 ligand with low nanomolar affinity. Two X-ray crystal structures of the key analogue 2i in the ligand-binding domain (LBD) of GluA2 and GluK3 were determined. Partial domain closure was seen in the GluA2-LBD complex with 2i comparable to that induced by kainate. In contrast, full domain closure was observed in the GluK3-LBD complex with 2i, similar to that of GluK3-LBD with glutamate bound.
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MESH Headings
- Animals
- Aspartate Aminotransferases/chemistry
- Brain/metabolism
- Catalysis
- Crystallography, X-Ray
- Glutamate Plasma Membrane Transport Proteins/metabolism
- Glutamates/chemical synthesis
- Glutamates/chemistry
- Glutamates/pharmacology
- Glutamic Acid/analogs & derivatives
- Glutamic Acid/chemical synthesis
- Glutamic Acid/chemistry
- Glutamic Acid/pharmacology
- HEK293 Cells
- Humans
- In Vitro Techniques
- Ketoglutaric Acids/chemical synthesis
- Ketoglutaric Acids/chemistry
- Ligands
- Models, Molecular
- Molecular Structure
- Radioligand Assay
- Rats
- Rats, Sprague-Dawley
- Receptors, AMPA/chemistry
- Receptors, AMPA/metabolism
- Receptors, Ionotropic Glutamate/chemistry
- Receptors, Ionotropic Glutamate/metabolism
- Receptors, Kainic Acid/chemistry
- Receptors, Kainic Acid/metabolism
- Receptors, N-Methyl-D-Aspartate/metabolism
- Stereoisomerism
- Structure-Activity Relationship
- GluK3 Kainate Receptor
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Affiliation(s)
- Zeinab Assaf
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen Ø, Denmark
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49
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Huynh TH, Abrahamsen B, Madsen KK, Gonzalez-Franquesa A, Jensen AA, Bunch L. Design, synthesis and pharmacological characterization of coumarin-based fluorescent analogs of excitatory amino acid transporter subtype 1 selective inhibitors, UCPH-101 and UCPH-102. Bioorg Med Chem 2012; 20:6831-9. [DOI: 10.1016/j.bmc.2012.09.049] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 09/24/2012] [Accepted: 09/25/2012] [Indexed: 11/30/2022]
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50
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The promiscuous binding of pharmaceutical drugs and their transporter-mediated uptake into cells: what we (need to) know and how we can do so. Drug Discov Today 2012. [PMID: 23207804 DOI: 10.1016/j.drudis.2012.11.008] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
A recent paper in this journal sought to counter evidence for the role of transport proteins in effecting drug uptake into cells, and questions that transporters can recognize drug molecules in addition to their endogenous substrates. However, there is abundant evidence that both drugs and proteins are highly promiscuous. Most proteins bind to many drugs and most drugs bind to multiple proteins (on average more than six), including transporters (mutations in these can determine resistance); most drugs are known to recognise at least one transporter. In this response, we alert readers to the relevant evidence that exists or is required. This needs to be acquired in cells that contain the relevant proteins, and we highlight an experimental system for simultaneous genome-wide assessment of carrier-mediated uptake in a eukaryotic cell (yeast).
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