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Chałupnik P, Szymańska E. Kainate Receptor Antagonists: Recent Advances and Therapeutic Perspective. Int J Mol Sci 2023; 24:1908. [PMID: 36768227 PMCID: PMC9916396 DOI: 10.3390/ijms24031908] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 01/06/2023] [Accepted: 01/16/2023] [Indexed: 01/21/2023] Open
Abstract
Since the 1990s, ionotropic glutamate receptors have served as an outstanding target for drug discovery research aimed at the discovery of new neurotherapeutic agents. With the recent approval of perampanel, the first marketed non-competitive antagonist of AMPA receptors, particular interest has been directed toward 'non-NMDA' (AMPA and kainate) receptor inhibitors. Although the role of AMPA receptors in the development of neurological or psychiatric disorders has been well recognized and characterized, progress in understanding the function of kainate receptors (KARs) has been hampered, mainly due to the lack of specific and selective pharmacological tools. The latest findings in the biology of KA receptors indicate that they are involved in neurophysiological activity and play an important role in both health and disease, including conditions such as anxiety, schizophrenia, epilepsy, neuropathic pain, and migraine. Therefore, we reviewed recent advances in the field of competitive and non-competitive kainate receptor antagonists and their potential therapeutic applications. Due to the high level of structural divergence among the compounds described here, we decided to divide them into seven groups according to their overall structure, presenting a total of 72 active compounds.
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Affiliation(s)
| | - Ewa Szymańska
- Department of Technology and Biotechnology of Drugs, Jagiellonian University Medical College in Kraków, PL 30-688 Kraków, Poland
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2
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Chałupnik P, Vialko A, Pickering DS, Hinkkanen M, Donbosco S, Møller TC, Jensen AA, Nielsen B, Bay Y, Kristensen AS, Johansen TN, Łątka K, Bajda M, Szymańska E. Discovery of the First Highly Selective Antagonist of the GluK3 Kainate Receptor Subtype. Int J Mol Sci 2022; 23:ijms23158797. [PMID: 35955932 PMCID: PMC9369419 DOI: 10.3390/ijms23158797] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 07/29/2022] [Accepted: 08/02/2022] [Indexed: 11/16/2022] Open
Abstract
Kainate receptors belong to the family of glutamate receptors ion channels, which are responsible for the majority of rapid excitatory synaptic transmission in the central nervous system. The therapeutic potential of kainate receptors is still poorly understood, which is also due to the lack of potent and subunit-selective pharmacological tools. In search of selective ligands for the GluK3 kainate receptor subtype, a series of quinoxaline-2,3-dione analogues was synthesized and pharmacologically characterized at selected recombinant ionotropic glutamate receptors. Among them, compound 28 was found to be a competitive GluK3 antagonist with submicromolar affinity and unprecedented high binding selectivity, showing a 400-fold preference for GluK3 over other homomeric receptors GluK1, GluK2, GluK5 and GluA2. Furthermore, in functional assays performed for selected metabotropic glutamate receptor subtypes, 28 did not show agonist or antagonist activity. The molecular determinants underlying the observed affinity profile of 28 were analyzed using molecular docking and molecular dynamics simulations performed for individual GluK1 and GluK3 ligand-binding domains.
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Affiliation(s)
- Paulina Chałupnik
- Department of Technology and Biotechnology of Drugs, Jagiellonian University Medical College in Kraków, 30-688 Kraków, Poland
| | - Alina Vialko
- Department of Technology and Biotechnology of Drugs, Jagiellonian University Medical College in Kraków, 30-688 Kraków, Poland
| | - Darryl S. Pickering
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Markus Hinkkanen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Stephanie Donbosco
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Thor C. Møller
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Anders A. Jensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Birgitte Nielsen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Yasmin Bay
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Anders S. Kristensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Tommy N. Johansen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Kamil Łątka
- Department of Physicochemical Drug Analysis, Jagiellonian University Medical College in Kraków, 30-688 Kraków, Poland
| | - Marek Bajda
- Department of Physicochemical Drug Analysis, Jagiellonian University Medical College in Kraków, 30-688 Kraków, Poland
| | - Ewa Szymańska
- Department of Technology and Biotechnology of Drugs, Jagiellonian University Medical College in Kraków, 30-688 Kraków, Poland
- Correspondence:
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3
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Choi DW. Excitotoxicity: Still Hammering the Ischemic Brain in 2020. Front Neurosci 2020; 14:579953. [PMID: 33192266 PMCID: PMC7649323 DOI: 10.3389/fnins.2020.579953] [Citation(s) in RCA: 91] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 09/25/2020] [Indexed: 12/13/2022] Open
Abstract
Interest in excitotoxicity expanded following its implication in the pathogenesis of ischemic brain injury in the 1980s, but waned subsequent to the failure of N-methyl-D-aspartate (NMDA) antagonists in high profile clinical stroke trials. Nonetheless there has been steady progress in elucidating underlying mechanisms. This review will outline the historical path to current understandings of excitotoxicity in the ischemic brain, and suggest that this knowledge should be leveraged now to develop neuroprotective treatments for stroke.
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Affiliation(s)
- Dennis W Choi
- Department of Neurology, SUNY Stony Brook, Stony Brook, NY, United States
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4
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Subunit-selective iGluR antagonists can potentiate heteromeric receptor responses by blocking desensitization. Proc Natl Acad Sci U S A 2020; 117:25851-25858. [PMID: 32999066 DOI: 10.1073/pnas.2007471117] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Ionotropic glutamate receptors (iGluRs) are key molecules for synaptic signaling in the central nervous system, which makes them promising drug targets. Intensive efforts are being devoted to the development of subunit-selective ligands, which should enable more precise pharmacologic interventions while limiting the effects on overall neuronal circuit function. However, many AMPA and kainate receptor complexes in vivo are heteromers composed of different subunits. Despite their importance, little is known about how subunit-selective ligands affect the gating of heteromeric iGluRs, namely their activation and desensitization properties. Using fast ligand application experiments, we studied the effects of competitive antagonists that block glutamate from binding at part of the four subunits. We found that UBP-310, a kainate receptor antagonist with high selectivity for GluK1 subunits, reduces the desensitization of GluK1/GluK2 heteromers and fully abolishes the desensitization of GluK1/GluK5 heteromers. This effect is mirrored by subunit-selective agonists and heteromeric receptors that contain binding-impaired subunits, as we show for both kainate and GluA2 AMPA receptors. These findings are consistent with a model in which incomplete agonist occupancy at the four receptor subunits can provide activation without inducing desensitization. However, we did not detect significant steady-state currents during UBP-310 dissociation from GluK1 homotetramers, indicating that antagonist dissociation proceeds in a nonuniform and cooperativity-driven manner, which disfavors nondesensitizing occupancy states. Besides providing mechanistic insights, these results have direct implications for the use of subunit-selective antagonists in neuroscience research and envisioned therapeutic interventions.
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Jaremko W, Huang Z, Karl N, Pierce VD, Lynch J, Niu L. A kainate receptor-selective RNA aptamer. J Biol Chem 2020; 295:6280-6288. [PMID: 32161119 PMCID: PMC7212664 DOI: 10.1074/jbc.ra119.011649] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Revised: 02/21/2020] [Indexed: 11/06/2022] Open
Abstract
Kainate and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors are two major, closely related receptor subtypes in the glutamate ion channel family. Excessive activities of these receptors have been implicated in a number of central nervous system diseases. Designing potent and selective antagonists of these receptors, especially of kainate receptors, is useful for developing potential treatment strategies for these neurological diseases. Here, we report on two RNA aptamers designed to individually inhibit kainate and AMPA receptors. To improve the biostability of these aptamers, we also chemically modified these aptamers by substituting their 2'-OH group with 2'-fluorine. These 2'-fluoro aptamers, FB9s-b and FB9s-r, were markedly resistant to RNase-catalyzed degradation, with a half-life of ∼5 days in rat cerebrospinal fluid or serum-containing medium. Furthermore, FB9s-r blocked AMPA receptor activity. Aptamer FB9s-b selectively inhibited GluK1 and GluK2 kainate receptor subunits, and also GluK1/GluK5 and GluK2/GluK5 heteromeric kainate receptors with equal potency. This inhibitory profile makes FB9s-b a powerful template for developing tool molecules and drug candidates for treatment of neurological diseases involving excessive activities of the GluK1 and GluK2 subunits.
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Affiliation(s)
- William Jaremko
- Department of Chemistry, and Center for Neuroscience Research, University at Albany, SUNY, Albany, New York 12222
| | - Zhen Huang
- Department of Chemistry, and Center for Neuroscience Research, University at Albany, SUNY, Albany, New York 12222
| | - Nicholas Karl
- Department of Chemistry, and Center for Neuroscience Research, University at Albany, SUNY, Albany, New York 12222
| | - Vincen D Pierce
- Department of Chemistry, and Center for Neuroscience Research, University at Albany, SUNY, Albany, New York 12222
| | - Janet Lynch
- Department of Chemistry, and Center for Neuroscience Research, University at Albany, SUNY, Albany, New York 12222
| | - Li Niu
- Department of Chemistry, and Center for Neuroscience Research, University at Albany, SUNY, Albany, New York 12222
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Domin H, Jantas D, Śmiałowska M. Neuroprotective effects of the allosteric agonist of metabotropic glutamate receptor 7 AMN082 on oxygen-glucose deprivation- and kainate-induced neuronal cell death. Neurochem Int 2015; 88:110-23. [PMID: 25576184 DOI: 10.1016/j.neuint.2014.12.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Revised: 12/07/2014] [Accepted: 12/17/2014] [Indexed: 12/24/2022]
Abstract
Although numerous studies demonstrated a neuroprotective potency of unspecific group III mGluR agonists in in vitro and in vivo models of excitotoxicity, little is known about the protective role of group III mGlu receptor activation against neuronal cell injury evoked by ischemic conditions. The aim of the present study was to assess neuroprotective potential of the allosteric agonist of mGlu7 receptor, N,N'-Bis(diphenylmethyl)-1,2-ethanediamine dihydrochloride (AMN082) against oxygen-glucose deprivation (OGD)- and kainate (KA)-evoked neuronal cell damage in primary neuronal cultures, with special focus on its efficacy after delayed application. We demonstrated that in cortical neuronal cultures exposed to a 180 min OGD, AMN082 (0.01-1 µM) in a concentration- and time-dependent way attenuated the OGD-induced changes in the LDH release and MTT reduction assays. AMN082 (0.5 and 1 µM) produced also neuroprotective effects against KA-evoked neurotoxicity both in cortical and hippocampal cultures. Of particular importance was the finding that AMN082 attenuated excitotoxic neuronal injury after delayed application (30 min after OGD, or 30 min-1 h after KA). In both models of neurotoxicity, namely OGD- and KA-induced injury, the neuroprotective effects of AMN082 (1 µM) were reversed by the selective mGlu7 antagonist, 6-(4-Methoxyphenyl)-5-methyl-3-(4-pyridinyl)-isoxazolo[4,5-c]pyridin-4(5H)-one hydrochloride (MMPIP, 1 µM), suggesting the mGlu7-dependent mechanism of neuroprotective effects of AMN082. Next, we showed that AMN082 (0.5 and 1 µM) attenuated the OGD-induced increase in the number of necrotic nuclei as well inhibited the OGD-evoked calpain activation, suggesting the participation of these processes in the mechanism of AMN082-mediated protection. Additionally, we showed that protection evoked by AMN082 (1 µM) in KA model was connected with the inhibition of toxin-induced caspase-3 activity, and this effect was abolished by the mGlu7 receptor antagonist. The obtained results indicated that the activation of mGlu7 receptors may be a promising target for neuroprotection against ischemic and excitotoxic insults.
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Affiliation(s)
- Helena Domin
- Department of Neurobiology, Institute of Pharmacology, Polish Academy of Sciences, Smętna 12, 31-343 Kraków, Poland.
| | - Danuta Jantas
- Department of Experimental Neuroendocrinology, Institute of Pharmacology, Polish Academy of Sciences, Smętna 12, 31-343 Kraków, Poland
| | - Maria Śmiałowska
- Department of Neurobiology, Institute of Pharmacology, Polish Academy of Sciences, Smętna 12, 31-343 Kraków, Poland
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7
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Kawamoto EM, Vivar C, Camandola S. Physiology and pathology of calcium signaling in the brain. Front Pharmacol 2012; 3:61. [PMID: 22518105 PMCID: PMC3325487 DOI: 10.3389/fphar.2012.00061] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Accepted: 03/26/2012] [Indexed: 12/31/2022] Open
Abstract
Calcium (Ca(2+)) plays fundamental and diversified roles in neuronal plasticity. As second messenger of many signaling pathways, Ca(2+) as been shown to regulate neuronal gene expression, energy production, membrane excitability, synaptogenesis, synaptic transmission, and other processes underlying learning and memory and cell survival. The flexibility of Ca(2+) signaling is achieved by modifying cytosolic Ca(2+) concentrations via regulated opening of plasma membrane and subcellular Ca(2+) sensitive channels. The spatiotemporal patterns of intracellular Ca(2+) signals, and the ultimate cellular biological outcome, are also dependent upon termination mechanism, such as Ca(2+) buffering, extracellular extrusion, and intra-organelle sequestration. Because of the central role played by Ca(2+) in neuronal physiology, it is not surprising that even modest impairments of Ca(2+) homeostasis result in profound functional alterations. Despite their heterogeneous etiology neurodegenerative disorders, as well as the healthy aging process, are all characterized by disruption of Ca(2+) homeostasis and signaling. In this review we provide an overview of the main types of neuronal Ca(2+) channels and their role in neuronal plasticity. We will also discuss the participation of Ca(2+) signaling in neuronal aging and degeneration.
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Affiliation(s)
- Elisa Mitiko Kawamoto
- Laboratory of Neurosciences, National Institute on Aging, Intramural Research ProgramBaltimore, MD, USA
| | - Carmen Vivar
- Laboratory of Neurosciences, National Institute on Aging, Intramural Research ProgramBaltimore, MD, USA
| | - Simonetta Camandola
- Laboratory of Neurosciences, National Institute on Aging, Intramural Research ProgramBaltimore, MD, USA
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8
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Irvine MW, Costa BM, Dlaboga D, Culley GR, Hulse R, Scholefield CL, Atlason P, Fang G, Eaves R, Morley R, Mayo-Martin MB, Amici M, Bortolotto ZA, Donaldson L, Collingridge GL, Molnár E, Monaghan DT, Jane DE. Piperazine-2,3-dicarboxylic acid derivatives as dual antagonists of NMDA and GluK1-containing kainate receptors. J Med Chem 2011; 55:327-41. [PMID: 22111545 DOI: 10.1021/jm201230z] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Competitive N-methyl-d-aspartate receptor (NMDAR) antagonists bind to the GluN2 subunit, of which there are four types (GluN2A-D). We report that some N(1)-substituted derivatives of cis-piperazine-2,3-dicarboxylic acid display improved relative affinity for GluN2C and GluN2D versus GluN2A and GluN2B. These derivatives also display subtype selectivity among the more distantly related kainate receptor family. Compounds 18i and (-)-4 were the most potent kainate receptor antagonists, and 18i was selective for GluK1 versus GluK2, GluK3 and AMPA receptors. Modeling studies revealed structural features required for activity at GluK1 subunits and suggested that S674 was vital for antagonist activity. Consistent with this hypothesis, replacing the equivalent residue in GluK3 (alanine) with a serine imparts 18i antagonist activity. Antagonists with dual GluN2D and GluK1 antagonist activity may have beneficial effects in various neurological disorders. Consistent with this idea, antagonist 18i (30 mg/kg ip) showed antinociceptive effects in an animal model of mild nerve injury.
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Affiliation(s)
- Mark W Irvine
- MRC Centre for Synaptic Plasticity, University of Bristol, Medical Sciences Building, University Walk, Bristol, BS8 1TD, U.K
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9
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Kostandy BB. The role of glutamate in neuronal ischemic injury: the role of spark in fire. Neurol Sci 2011; 33:223-37. [PMID: 22044990 DOI: 10.1007/s10072-011-0828-5] [Citation(s) in RCA: 143] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2010] [Accepted: 10/20/2011] [Indexed: 12/21/2022]
Abstract
Although being a physiologically important excitatory neurotransmitter, glutamate plays a pivotal role in various neurological disorders including ischemic neurological diseases. Its level is increased during cerebral ischemia with excessive neurological stimulation causing the glutamate-induced neuronal toxicity, excitotoxicity, and this is considered the triggering spark in the ischemic neuronal damage. The glutamatergic stimulation will lead to rise in the intracellular sodium and calcium, and the elevated intracellular calcium will lead to mitochondrial dysfunction, activation of proteases, accumulation of reactive oxygen species and release of nitric oxide. Interruption of the cascades of glutamate-induced cell death during ischemia may provide a way to prevent, or at least reduce, the ischemic damage. Various therapeutic options are suggested interrupting the glutamatergic pathways, e.g., inhibiting the glutamate synthesis or release, increasing its clearance, blocking of its receptors or preventing the rise in intracellular calcium. Development of these strategies may provide future treatment options in the management of ischemic stroke.
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Affiliation(s)
- Botros B Kostandy
- Department of Pharmacology, Faculty of Medicine, University of Assiut, Assiut 71526, Egypt.
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Ofengeim D, Miyawaki T, Suzanne zukin R. Molecular and Cellular Mechanisms of Ischemia-Induced Neuronal Death. Stroke 2011. [DOI: 10.1016/b978-1-4160-5478-8.10006-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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11
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Abstract
Glutamate receptors are key mediators of brain communication. Among ionotropic glutamate receptors, kainate receptors (KARs) have been least explored and their relevance to pathophysiology is relatively obscure. This is in part due to the relatively low abundance of KARs, the regulatory function in network activity they play, the lack of specific agonists and antagonists for this receptor subtype, as well as to the absence of striking phenotypes in mice deficient in KAR subunits. Nonetheless, it is now well established that KARs are located presynaptically whereby they regulate glutamate and GABA release, and thus, excitability and participate in short‐term plasticity. In turn, KARs are also located postsynaptically and their activation contributes to synaptic integration. The development of specific novel ligands is helping to further investigate the contribution of KARs to health and disease. In this review, I summarize current knowledge about KAR physiology and pharmacology, and discuss their involvement in cell death and disease. In addition, I recapitulate the available data about the use of KAR antagonists and receptor subunit deficient mice in experimental paradigms of brain diseases, as well as the main findings about KAR roles in human CNS disorders. In sum, subunit specific antagonists have therapeutic potential in neurodegenerative and psychiatric diseases as well as in epilepsy and pain. Knowledge about the genetics of KARs will also help to understand the pathophysiology of those and other illnesses.
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Affiliation(s)
- Carlos Matute
- Centro de Investigación Biomédica en Red en Enfermedades Neurodegenerativas (CIBERNED) and Departamento de Neurociencias, Universidad del País Vasco, 48940-Leioa, Spain.
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12
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Benveniste M, Wilhelm J, Dingledine RJ, Mott DD. Subunit-dependent modulation of kainate receptors by muscarinic acetylcholine receptors. Brain Res 2010; 1352:61-9. [PMID: 20655886 DOI: 10.1016/j.brainres.2010.07.029] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2010] [Revised: 07/10/2010] [Accepted: 07/13/2010] [Indexed: 10/19/2022]
Abstract
Interactions between cholinergic and glutamatergic neurotransmitter systems influence synaptic transmission and plasticity. While previous studies have examined cross-talk between acetylcholine (ACh) and NMDA or AMPA receptors, little is known about the effect of ACh on kainate receptors (KARs). We show that stimulation of m1 or m3 muscarinic ACh receptors (mAChRs) for 2min potentiates recombinant KAR currents in a long lasting fashion. Muscarinic AChR activation potentiates heteromeric GluK2/GluK4 and GluK2/GluK5 receptors, but not homomeric GluK2 receptors. In hippocampal slices kainate potentiates mossy fiber axon excitability. Transient mAChR activation enhances this action of kainate, suggesting a novel mechanism through which acetylcholine could modulate synaptic transmission in the hippocampus. KAR over-activation has been implicated in excitotoxic cell death. To establish the functional significance of the interaction between mAChRs and KARs we examined the effect of mAChR activation on KAR-mediated excitotoxicity. We find that during pharmacological blockade of NMDA and AMPA receptors, KAR activation with AMPA produces significant cell death in primary cortical culture. Concanavalin A (Con A), which selectively blocks KAR desensitization, markedly increases this KAR-mediated neurotoxicity. Brief activation of mAChRs with pilocarpine significantly enhances KAR-mediated excitotoxicity both in the presence and absence of Con A. We conclude that KARs are modulated in a subunit dependent manner by mAChRs. We suggest that ACh may induce long lasting alterations in neuronal excitability and enhance excitotoxicity in part by potentiating KAR function.
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Affiliation(s)
- Morris Benveniste
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA 30310, USA
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13
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Alushin GM, Jane D, Mayer ML. Binding site and ligand flexibility revealed by high resolution crystal structures of GluK1 competitive antagonists. Neuropharmacology 2010; 60:126-34. [PMID: 20558186 DOI: 10.1016/j.neuropharm.2010.06.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2010] [Accepted: 06/08/2010] [Indexed: 11/28/2022]
Abstract
The availability of crystal structures for the ligand binding domains of ionotropic glutamate receptors, combined with their key role in synaptic function in the normal and diseased brain, offers a unique selection of targets for pharmaceutical research compared to other drug targets for which the atomic structure of the ligand binding site is not known. Currently only a few antagonist structures have been solved, and these reveal ligand specific conformational changes that hinder rational drug design. Here we report high resolution crystal structures for three kainate receptor GluK1 antagonist complexes which reveal new and unexpected modes of binding, highlighting the continued need for experimentally determined receptor-ligand complexes.
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Affiliation(s)
- Gregory M Alushin
- Laboratory of Cellular and Molecular Neurophysiology, Porter Neuroscience Research Center, NICHD, NIH, DHHS, Bethesda, MD 20892, USA
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14
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Antonucci F, Cerri C, Maya Vetencourt JF, Caleo M. Acute neuroprotection by the synaptic blocker botulinum neurotoxin E in a rat model of focal cerebral ischaemia. Neuroscience 2010; 169:395-401. [PMID: 20447449 DOI: 10.1016/j.neuroscience.2010.04.059] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2009] [Revised: 04/09/2010] [Accepted: 04/25/2010] [Indexed: 11/24/2022]
Abstract
Evidence indicates that accumulation of excitotoxic mediators, such as glutamate, contributes to neuronal damage after an ischaemic insult. It is not clear, however, whether this accumulation is due to excess synaptic release or to impaired uptake. To test a role for synaptic release, here we investigated the neuroprotective potential of the synaptic blocker botulinum neurotoxin E (BoNT/E), that prevents vesicle fusion via the cleavage of the SNARE (soluble NSF-attachment receptor) protein SNAP-25 (synaptosomal-associated protein of 25 kDa). Focal ischaemia was induced in vivo by infusing the potent vasoconstricting peptide endothelin-1 (ET-1) into the CA1 area of the hippocampus in adult rats; BoNT/E or vehicle were administered into the same site 20 min later. Injection of ET-1 was found to produce a transient and massive increase in glutamate release that was potently antagonized by BoNT/E. To assess whether blocking transmitter release translates into neuroprotection, the extent of the ischaemic damage was determined 24 h and 6 weeks after the insult. We found that BoNT/E administration consistently reduced the loss of CA1 pyramidal neurons at 24 h. The neuroprotective effect of BoNT/E, however, was no longer significant at 6 weeks. These data provide evidence that blockade of synaptic transmitter release delays neuronal cell death following focal brain ischaemia, and underline the importance of assessing long-term neuroprotection in experimental stroke studies.
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Affiliation(s)
- F Antonucci
- Istituto di Neuroscienze, Consiglio Nazionale delle Ricerche, via G. Moruzzi 1, 56100 Pisa, Italy
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GLUK1 receptor antagonists and hippocampal mossy fiber function. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2009; 85:13-27. [PMID: 19607958 DOI: 10.1016/s0074-7742(09)85002-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Kainate receptors, one of the three subtypes of ionotropic receptors for the excitatory transmitter l-glutamate, play a variety of functions in the regulation of synaptic activity. Their physiological properties and functional roles have been identified only recently, following the discovery of selective pharmacological tools that allow for isolation of kainate receptor-mediated events. A considerable amount of data indicates that this class of glutamate receptors is located both at the pre- and postsynaptic site, playing a special role in regulating transmission and controlling short- and long-term plasticity. In this review, we summarize some data obtained in our laboratory over the last decade illustrating how various ligands have contributed to our understanding of the physiological role for neuronal kainate receptors. In particular, we show that the GluK1-containing KARs are important for regulating synaptic facilitation and LTP induction at hippocampal mossy fiber synapses.
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17
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Kainate receptors: Pharmacology, function and therapeutic potential. Neuropharmacology 2009; 56:90-113. [DOI: 10.1016/j.neuropharm.2008.08.023] [Citation(s) in RCA: 203] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2008] [Revised: 08/04/2008] [Accepted: 08/07/2008] [Indexed: 01/28/2023]
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18
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Moult PR, Harvey J. Hormonal regulation of hippocampal dendritic morphology and synaptic plasticity. Cell Adh Migr 2008; 2:269-75. [PMID: 19262152 DOI: 10.4161/cam.2.4.6354] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The peripheral functions of hormones such as leptin, insulin and estrogens are well documented. An important and rapidly expanding field is demonstrating that as well as their peripheral actions, these hormones play an important role in modulating synaptic function and structure within the CNS. The hippocampus is a major mediator of spatial learning and memory and is also an area highly susceptible to epileptic seizure. As such, the hippocampus has been extensively studied with particular regard to synaptic plasticity, a process thought to be necessary for learning and memory. Modulators of hippocampal function are therefore of particular interest, not only as potential modulators of learning and memory processes, but also with regard to CNS driven diseases such as epilepsy. Hormones traditionally thought of as only having peripheral roles are now increasingly being shown to have an important role in modulating synaptic plasticity and dendritic morphology. Here we review recent findings demonstrating that a number of hormones are capable of modulating both these phenomena.
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Affiliation(s)
- Peter R Moult
- Neurosciences Institute, Division of Pathology and Neuroscience, Ninewells Hospital and Medical School, University of Dundee, Dundee, UK
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19
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Xu J, Liu Y, Zhang GY. Neuroprotection of GluR5-containing kainate receptor activation against ischemic brain injury through decreasing tyrosine phosphorylation of N-methyl-D-aspartate receptors mediated by Src kinase. J Biol Chem 2008; 283:29355-66. [PMID: 18678878 DOI: 10.1074/jbc.m800393200] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Previous studies indicate that cerebral ischemia breaks the dynamic balance between excitatory and inhibitory inputs. The neural excitotoxicity induced by ionotropic glutamate receptors gain the upper hand during ischemia-reperfusion. In this paper, we investigate whether GluR5 (glutamate receptor 5)-containing kainate receptor activation could lead to a neuroprotective effect against ischemic brain injury and the related mechanism. The results showed that (RS)-2-amino-3-(3-hydroxy-5-tert-butylisoxazol-4-yl) propanoic acid (ATPA), a selective GluR5 agonist, could suppress Src tyrosine phosphorylation and interactions among N-methyl-D-aspartate (NMDA) receptor subunit 2A (NR2A), postsynaptic density protein 95 (PSD-95), and Src and then decrease NMDA receptor activation through attenuating tyrosine phosphorylation of NR2A and NR2B. More importantly, ATPA had a neuroprotective effect against ischemia-reperfusion-induced neuronal cell death in vivo. However, four separate drugs were found to abolish the effects of ATPA. These were selective GluR5 antagonist NS3763; GluR5 antisense oligodeoxynucleotides; CdCl(2), a broad spectrum blocker of voltage-gated calcium channels; and bicuculline, an antagonist of gamma-aminobutyric acid A (GABA(A)) receptor. GABA(A) receptor agonist muscimol could attenuate Src activation and interactions among NR2A, PSD-95 and Src, resulting the suppression of NMDA receptor tyrosine phosphorylation. Moreover, patch clamp recording proved that the activated GABA(A) receptor could inhibit NMDA receptor-mediated whole-cell currents. Taken together, the results suggest that during ischemia-reperfusion, activated GluR5 may facilitate Ca(2+)-dependent GABA release from interneurons. The released GABA can activate postsynaptic GABA(A) receptors, which then attenuates NMDA receptor tyrosine phosphorylation through inhibiting Src activation and disassembling the signaling module NR2A-PSD-95-Src. The final result of this process is that the pyramidal neurons are rescued from hyperexcitability.
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Affiliation(s)
- Jie Xu
- Research Center for Biochemistry and Molecular Biology, Jiangsu Key Laboratory of Brain Disease Bio-information, Xuzhou Medical College, Xuzhou 221002, China
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20
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Moyanova SG, Kortenska LV, Mitreva RG, Pashova VD, Ngomba RT, Nicoletti F. Multimodal assessment of neuroprotection applied to the use of MK-801 in the endothelin-1 model of transient focal brain ischemia. Brain Res 2007; 1153:58-67. [PMID: 17466282 DOI: 10.1016/j.brainres.2007.03.070] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2007] [Revised: 03/23/2007] [Accepted: 03/24/2007] [Indexed: 11/28/2022]
Abstract
Transient focal ischemia produced by local infusion of endothelin-1 (ET1) in the territory of the middle cerebral artery has been proposed as a potentially useful model for the screening of drugs developed for the treatment of thrombo-embolic stroke. However, most of the data rely exclusively on the assessment of the infarct volume, which is only a partial predictor of the neurological outcome of stroke. Here, we have validated the model using a multimodal approach for the assessment of neuroprotection, which includes (i) determination of the infarct volume by 2,3,5-triphenyltetrazolium chloride staining; (ii) an in-depth behavioral analysis of the neurological deficit; and (iii) an EEG analysis of electrophysiological abnormalities in the peri-infarct somatosensory forelimb cortical area, S1FL. The non-competitive NMDA receptor antagonist, MK-801 (3 mg/kg, injected i.p. 20 min after ET1 infusion in conscious rats) could reduce the infarct volume, reverse the EEG changes occurring at early times post-ET1, and markedly improve the neurological deficit in ischemic animals. The latter effect, however, was visible at day 3 post-ET1, because the drug itself produced substantial behavioral abnormalities at earlier times. We conclude that a multimodal approach can be applied to the ET1 model of focal ischemia, and that MK-801 can be used as a reference compound to which the activity of safer neuroprotective drugs should be compared.
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Affiliation(s)
- Slavianka Georgieva Moyanova
- Department of Neurobiology of Adaptation, Laboratory of Integrative Neuropharmacology, Institute of Neurobiology, Bulgarian Academy of Sciences, Sofia, Bulgaria.
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21
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Dolman NP, More JCA, Alt A, Knauss JL, Pentikäinen OT, Glasser CR, Bleakman D, Mayer ML, Collingridge GL, Jane DE. Synthesis and Pharmacological Characterization of N3-Substituted Willardiine Derivatives: Role of the Substituent at the 5-Position of the Uracil Ring in the Development of Highly Potent and Selective GLUK5Kainate Receptor Antagonists. J Med Chem 2007; 50:1558-70. [PMID: 17348638 DOI: 10.1021/jm061041u] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Some N3-substituted analogues of willardiine such as 11 and 13 are selective kainate receptor antagonists. In an attempt to improve the potency and selectivity for kainate receptors, a range of analogues of 11 and 13 were synthesized with 5-substituents on the uracil ring. An X-ray crystal structure of the 5-methyl analogue of 13 bound to GLUK5 revealed that there was allowed volume around the 4- and 5-positions of the thiophene ring, and therefore the 4,5-dibromo and 5-phenyl (67) analogues were synthesized. Compound 67 (ACET) demonstrated low nanomolar antagonist potency on native and recombinant GLUK5-containing kainate receptors (KB values of 7 +/- 1 and 5 +/- 1 nM for antagonism of recombinant human GLUK5 and GLUK5/GLUK2, respectively) but displayed IC50 values >100 microM for antagonism of GLUA2, GLUK6, or GLUK6/GLUK2.
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MESH Headings
- Alanine/analogs & derivatives
- Alanine/chemical synthesis
- Alanine/chemistry
- Alanine/pharmacology
- Animals
- Animals, Newborn
- Binding Sites
- Calcium/metabolism
- Cell Line
- Crystallography, X-Ray
- Humans
- In Vitro Techniques
- Ligands
- Models, Molecular
- Motor Neurons/drug effects
- Motor Neurons/physiology
- Nerve Fibers, Unmyelinated/drug effects
- Nerve Fibers, Unmyelinated/physiology
- Protein Conformation
- Pyrimidinones/chemical synthesis
- Pyrimidinones/chemistry
- Pyrimidinones/pharmacology
- Rats
- Receptors, AMPA/antagonists & inhibitors
- Receptors, AMPA/genetics
- Receptors, AMPA/physiology
- Receptors, Kainic Acid/antagonists & inhibitors
- Receptors, Kainic Acid/genetics
- Receptors, Kainic Acid/physiology
- Recombinant Proteins/antagonists & inhibitors
- Recombinant Proteins/genetics
- Spinal Nerve Roots/drug effects
- Spinal Nerve Roots/physiology
- Stereoisomerism
- Structure-Activity Relationship
- Uracil/analogs & derivatives
- Uracil/chemical synthesis
- Uracil/chemistry
- Uracil/pharmacology
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Affiliation(s)
- Nigel P Dolman
- Department of Pharmacology, MRC Centre for Synaptic Plasticity, School of Medical Sciences, University Walk, University of Bristol, Bristol BS8 1TD, United Kingdom
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22
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Christensen RN, Ha BK, Sun F, Bresnahan JC, Beattie MS. Kainate induces rapid redistribution of the actin cytoskeleton in ameboid microglia. J Neurosci Res 2006; 84:170-81. [PMID: 16625662 DOI: 10.1002/jnr.20865] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Microglia are key mediators of the immune response in the central nervous system (CNS). They are closely related to macrophages and undergo dramatic morphological and functional changes after CNS trauma or excitotoxic lesions. Microglia can be directly stimulated by excitatory neurotransmitters and are known to express many neurotransmitter receptors. The role of these receptors, however, is not clear. This study describes the microglial response to the glutamate receptor agonist kainate (KA) and shows via immunochemistry that the alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA)-type glutamate receptor subunit GluR1 is present on cultured microglia. In the presence of 100 microM or 1 mM KA, cultured microglia underwent dramatic morphological and cytoskeletal changes as observed by time-lapse photography and quantitative confocal analysis of phalloidin labeling. KA-stimulated microglia showed condensation of cytoplasmic actin filaments, rapid de- and repolymerization, and cytoplasmic redistribution of condensed actin bundles. Rearrangement of actin filaments-thought to be involved in locomotion and phagocytosis and to indicate an increased level of activation (for reviews see Greenberg [ 1995] Trends Cell Biol. 5:93-99; Imai and Kohsaka [ 2002] Glia 40:164-174)-was significantly increased in treated vs. control cultures. Morphological plasticity and membrane ruffling were also seen. These findings suggest direct microglial excitation via glutamate receptor pathways. Thus, neurotransmitter release after brain or spinal cord injury might directly modulate the inflammatory response.
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23
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Katsumata N, Kuroiwa T, Ishibashi S, Li S, Endo S, Ohno K. Heterogeneous hyperactivity and distribution of ischemic lesions after focal cerebral ischemia in Mongolian gerbils. Neuropathology 2006; 26:283-92. [PMID: 16961063 DOI: 10.1111/j.1440-1789.2006.00696.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Various types of poststroke hyperactivity exist in humans, but studies of each mechanism using animal models are scarce. We aimed to analyze the heterogeneity of postischemic hyperlocomotion and to identify the ischemic lesions responsible for postischemic hyperlocomotion in rodent models of focal ischemia. Mongolian gerbils underwent right common carotid artery occlusion (CCAO) for 10 or 20 min. At 24 h, 2 days, and 7 days postischemia, we performed quantitative and qualitative locomotor analysis and correlated these results with the extent of ischemic lesions. Intermittent explosive hyperlocomotion was induced transiently in a 10-min CCAO group at 24 h after ischemia and continual unexplosive hyperlocomotion persisted for 7 days in the 20-min CCAO animals. Selective neuronal death, confined to the hippocampal cornu ammonis 1 (CA1), was observed in the 10-min CCAO group and widespread cortical and basal ganglia infarction was observed in the 20-min CCAO group. Amyloid precursor protein was transiently observed in the hippocampus at 24 h postischemia in the 10-min CCAO animals, while it was widely distributed over the ischemic regions throughout the 7 days postischemia in the 20-min CCAO animals. Incidence maps and correlation analysis revealed hippocampal neuronal death of the CA1 sector and widespread hemispheric infarction, including the cortex, as the region responsible for the 10-min and 20-min CCAO-induced hyperactivity, respectively. Two distinct types of locomotor hyperactivity were observed that varied with regard to the distribution of the ischemic lesion, that is, hippocampal neuronal death and widespread infarction involving the cortex. These two types of locomotor hyperactivity appear to be models of the different types of poststroke hyperactivity seen in stroke patients.
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Affiliation(s)
- Noriko Katsumata
- Department of Neurosurgery, Graduate School of Medicine, Tokyo Medical and Dental University, Japan.
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24
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Abstract
Kainate receptors form a family of ionotropic glutamate receptors that appear to play a special role in the regulation of the activity of synaptic networks. This review first describes briefly the molecular and pharmacological properties of native and recombinant kainate receptors. It then attempts to outline the general principles that appear to govern the function of kainate receptors in the activity of synaptic networks under physiological conditions. It subsequently describes the way that kainate receptors are involved in synaptic integration, synaptic plasticity, the regulation of neurotransmitter release and the control of neuronal excitability, and the manner in which they might play an important role in synaptogenesis and synaptic maturation. These functions require the proper subcellular localization of kainate receptors in specific functional domains of the neuron, necessitating complex cellular and molecular trafficking events. We show that our comprehension of these mechanisms is just starting to emerge. Finally, this review presents evidence that implicates kainate receptors in pathophysiological conditions such as epilepsy, excitotoxicity and pain, and that shows that these receptors represent promising therapeutic targets.
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Affiliation(s)
- Paulo Pinheiro
- CNRS UMR 5091, Laboratoire "Physiologie Cellulaire de la Synapse", Bordeaux Neuroscience Institute, University of Bordeaux, 33077 Bordeaux Cedex, France
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25
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Dolman NP, More JCA, Alt A, Knauss JL, Troop HM, Bleakman D, Collingridge GL, Jane DE. Structure-activity relationship studies on N3-substituted willardiine derivatives acting as AMPA or kainate receptor antagonists. J Med Chem 2006; 49:2579-92. [PMID: 16610801 DOI: 10.1021/jm051086f] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
N3-substitution of the uracil ring of willardiine with a variety of carboxyalkyl or carboxybenzyl substituents produces AMPA and kainate receptor antagonists. In an attempt to improve the potency and selectivity of these AMPA and kainate receptor antagonists a series of analogues with different terminal acidic groups and interacidic group spacers was synthesized and pharmacologically characterized. (S)-1-(2-Amino-2-carboxyethyl)-3-(2-carboxythiophene-3-ylmethyl)pyrimidine-2,4-dione (43, UBP304) demonstrated high potency and selectivity toward native GLU(K5)-containing kainate receptors (K(D) 0.105 +/- 0.007 microM vs kainate on native GLU(K5); K(D) 71.4 +/- 8.3 microM vs (S)-5-fluorowillardiine on native AMPA receptors). On recombinant human GLU(K5), GLU(K5)/GLU(K6), and GLU(K5)/GLU(K2), K(B) values of 0.12 +/- 0.03, 0.12 +/- 0.01, and 0.18 +/- 0.02 microM, respectively, were obtained for 43. However, 43 displayed no activity on homomeric GLU(K6) or GLU(K7) kainate receptors or homomeric GLU(A1-4) AMPA receptors (IC(50) values > 100 microM). Thus, 43 is a potent and selective GLU(K5) receptor antagonist.
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Affiliation(s)
- Nigel P Dolman
- Department of Pharmacology, MRC Centre for Synaptic Plasticity, School of Medical Sciences, University Walk, University of Bristol, Bristol BS8 1TD, UK
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26
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Pentikäinen U, Settimo L, Johnson MS, Pentikäinen OT. Subtype selectivity and flexibility of ionotropic glutamate receptors upon antagonist ligand binding. Org Biomol Chem 2006; 4:1058-70. [PMID: 16525550 DOI: 10.1039/b515111b] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The binding modes of a set of known ionotropic glutamate receptor antagonist-ligands have been studied using homology modeling, molecular docking, molecular dynamics (MD) simulations and ab initio quantum mechanical calculations. The core structure of the studied ligands is the decahydroisoquinoline ring, which has a carboxylic acid group at position three and different negatively-charged substituents (R) at position six. The binding affinities of these molecules have been reported earlier. From the current study, the carboxylate group of the decahydroisoquinoline ring hydrogen bonds with Arg485, the amino group with Pro478 and Thr480, and the negatively charged substituent R interacts with the positively charged N-terminus of helix-F. The subtype selectivity of these ligands seems to be strongly dependent on the amino acid at position 650 (GluR2: leucine, GluR5: valine), which affects the conformation of the ligand and ligand-receptor interactions, but depends considerably on the size of the R-group of the ligand. In addition, the MD simulations also revealed that the relative positions of the S1 and S2 domains can alter significantly showing different "closure" and "rotational movements" depending on the antagonist-ligand that is bound. Accordingly, molecular docking of antagonist ligands into static crystal structures cannot sufficiently explain ligand binding and subtype selectivity.
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Affiliation(s)
- Ulla Pentikäinen
- Department of Biochemistry and Pharmacy, Abo Akademi University, Tykistökatu 6A, FIN-20520, Turku, Finland
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27
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Dolman NP, Troop HM, More JCA, Alt A, Knauss JL, Nistico R, Jack S, Morley RM, Bortolotto ZA, Roberts PJ, Bleakman D, Collingridge GL, Jane DE. Synthesis and Pharmacology of Willardiine Derivatives Acting as Antagonists of Kainate Receptors. J Med Chem 2005; 48:7867-81. [PMID: 16302825 DOI: 10.1021/jm050584l] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The natural product willardiine (8) is an AMPA receptor agonist while 5-iodowillardiine (10) is a selective kainate receptor agonist. In an attempt to produce antagonists of kainate and AMPA receptors analogues of willardiine with substituents at the N3 position of the uracil ring were synthesized. The N3-4-carboxybenzyl substituted analogue (38c) was found to be equipotent at AMPA and GLUK5-containing kainate receptors in the neonatal rat spinal cord. The N3-2-carboxybenzyl substituted analogue (38a) proved to be a potent and selective GLUK5 subunit containing kainate receptor antagonist when tested on native rat and human recombinant AMPA and kainate receptor subtypes. The GLUK5 kainate receptor antagonist activity was found to reside in the S enantiomer (44a) whereas the R enantiomer (44b) was almost inactive. 5-Iodo substitution of the uracil ring of 44a gave 45, which was found to have enhanced potency and selectivity for GLUK5.
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Affiliation(s)
- Nigel P Dolman
- Department of Pharmacology, MRC Centre for Synaptic Plasticity, School of Medical Sciences, University Walk, University of Bristol, Bristol, BS8 1TD, UK
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28
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O'neill MF, Sanger G, Ornstein PL, Osborne DJ, Woodhouse SM. Locomotor activity detects subunit-selective effects of agonists and decahydroisoquinoline antagonists at AMPA/kainic acid ionotropic glutamate receptors in adult rats. Psychopharmacology (Berl) 2005; 179:181-8. [PMID: 15821949 DOI: 10.1007/s00213-004-2055-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2004] [Accepted: 09/28/2004] [Indexed: 10/25/2022]
Abstract
RATIONALE In vitro studies have identified a series of decahydroisoquinoline compounds with differential selectivity for the subunits that comprise AMPA/kainic acid receptors. Compounds have been identified that have preferential activity at AMPA receptors (LY302679), whereas others (LY377770) have affinity for GluR5-kainic acid preferring subunit, which is activated by ATPA and kainic acid. OBJECTIVES These studies set out to determine if locomotor activity could differentiate these profiles in vivo. METHODS Locomotor activity was assessed in photocell drums in male Lister Hooded rats. RESULTS AMPA, kainic acid and the GluR5 selective agonist ATPA, all suppressed spontaneous locomotor activity (SLA) in rats at doses of 1.0, 5.0 and 20 mg/kg resp. All three agonists achieve micromolar concentrations measured in whole brain after dosing with 10 mg/kg SC. The decahydroisoquinoline antagonist compounds, LY302679 (GluR2), LY293558 (GluR2, 5) and LY377770 (GluR5) all decreased SLA in rats (ED(min) 2.5, 5.0 and 20 mg/kg respectively). The rank order of potency at GluR2 subunits (LY302679>LY293558>LY377770) was reflected in the same rank order of activity for suppression of SLA. LY293558 reversed the suppression of SLA induced by all three agonists (0.62--2.5 mg/kg). LY377770 reversed the effects of ATPA only (ED(min) 1.0 mg/kg), LY302679 (ED(min) 2.5 mg/kg) attenuated the effect of kainic acid but was ineffective against AMPA and ATPA. CONCLUSIONS Both agonist and antagonist suppression of SLA is associated with greater affinity for the GluR2 subunit, while compounds with affinity for the GluR5 subunit were less potent in suppressing SLA.
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Affiliation(s)
- Michael F O'neill
- Lilly Research Centre, Erl Wood Manor, Windlesham, Surrey GU20 6PH, UK.
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29
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Van Hemelrijck A, Sarre S, Smolders I, Michotte Y. Determination of amino acids associated with cerebral ischaemia in rat brain microdialysates using narrowbore liquid chromatography and fluorescence detection. J Neurosci Methods 2004; 144:63-71. [PMID: 15848240 DOI: 10.1016/j.jneumeth.2004.10.013] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2004] [Revised: 10/14/2004] [Accepted: 10/14/2004] [Indexed: 11/20/2022]
Abstract
Microdialysis coupled to liquid chromatography (LC) has proven to be a valuable in vivo sampling technique for studying neurotransmitter changes in normal and ischaemic brain. However, few analytical methods have described the simultaneous determination of amino acids, relevant in stroke research, together with the nitric-oxide-related compound citrulline. Therefore, we developed a gradient LC method for the quantitative simultaneous determination of aspartate, glutamate, serine, glutamine, arginine, taurine, alanine and citrulline in dialysates of rat brain using narrowbore LC with o-phthalaldehyde-2-mercaptoethanol pre-column derivatisation and fluorescence detection. The proposed method is a thoroughly validated, fully automated and robust LC method for the determination of amino acids in a wide concentration range. The method was applied for the determination of amino acids and the citrulline/arginine ratio in the Et-1 model for focal cerebral ischaemia.
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Affiliation(s)
- An Van Hemelrijck
- Department of Pharmaceutical Chemistry and Drug Analysis, Research Group Experimental Pharmacology, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium
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Valgeirsson J, Nielsen EO, Peters D, Mathiesen C, Kristensen AS, Madsen U. Bioisosteric Modifications of 2-Arylureidobenzoic Acids: Selective Noncompetitive Antagonists for the Homomeric Kainate Receptor Subtype GluR5. J Med Chem 2004; 47:6948-57. [PMID: 15615543 DOI: 10.1021/jm030638w] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
2-Arylureidobenzoic acids (AUBAs) have recently been presented as the first series of selective noncompetitive GluR5 antagonists. In this paper we have modified the acidic moiety of the AUBAs by introducing different acidic and neutral groups, and similarly, we have replaced the urea linker of the AUBAs with other structurally related linkers. Replacing the acid with neutral substituents led to inactive compounds in all instances, showing that an acidic moiety is necessary for activity. Replacing the carboxylic moiety in 2a with a sulfonic acid (5c) or a tetrazole ring (5d) improved the potency at GluR5 receptors (compounds 5c and 5d showed IC(50) values of 1.5 and 2.0 muM, respectively, compared to compound 2a with IC(50) = 4.8 muM). Compound 5c did not show improved in vivo activity in the ATPA rigidity test compared to 2a, whereas compound 5d was 4 times more potent than 2a. All compounds wherein the urea linker had been replaced showed lower or no activity. The results described extend the knowledge of structure-activity relationships for the AUBAs, and compound 5d may prove to be a good candidate for studying GluR5 receptors in vitro and in vivo.
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Affiliation(s)
- Jon Valgeirsson
- Department of Medicinal Chemistry, The Danish University of Pharmaceutical Sciences, 2 Universitetsparken, DK-2100 Copenhagen, Denmark
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31
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Khan S, Milot M, Lecompte-Collin J, Plamondon H. Time-dependent changes in CRH concentrations and release in discrete brain regions following global ischemia: effects of MK-801 pretreatment. Brain Res 2004; 1016:48-57. [PMID: 15234251 DOI: 10.1016/j.brainres.2004.04.062] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/15/2004] [Indexed: 10/26/2022]
Abstract
The excitatory actions of corticotropin-releasing hormone (CRH) in the brain and the neuroprotective effects of CRH antagonists in models of ischemia suggest a role for this peptide in the cascade of events leading to cellular damage. The present study aimed to characterize endogenous activation of CRH in discrete brain regions following global ischemia. Time-dependent changes in CRH concentrations were assessed in 10 brain regions including hippocampal, parahippocampal, and hypothalamic regions as well as the amygdala and the frontal cortex at three post-ischemic intervals: 4, 24, and 72 h (Experiment 1). The impact of pretreatment with a neuroprotective dose of the NMDA antagonist (5R,10S)-(+)-5-Methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine hydrogen maleate (MK-801; hydrogen maleate) on 24-h ischemia-induced CRH concentrations in the 10 brain regions was also determined (Experiment 2). In vivo microdialysis was used to assess dynamic fluctuations in CRH release at the dorsal hippocampus (CA1 pyramidal layer) and central nucleus of the amygdala (CeA; Experiment 3). Our findings revealed a rapid elevation of CRH concentrations at the piriform cortex (Pir) and hypothalamic nuclei following global ischemia. This was followed by decreased CRH concentrations at the amygdala, the frontal cortex (FC), the CA3, and the hypothalamus 24-h post-ischemia. MK-801 reversed the decreases in the hypothalamic nuclei but not in the other brain regions. Seventy-two hours post-ischemia, CRH levels returned to control values in all regions except the dentate gyrus (DG) where elevated CRH levels were observed. In vivo, a significant increase in CRH release in response to global ischemia was found at the CeA with no alterations at the CA1. These findings support brain region-specific ischemia-induced CRH alterations and suggest that CRH actions to mediate neuronal damage at the hippocampal CA1 layer may be indirect.
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Affiliation(s)
- Samir Khan
- University of Michigan, Department of Psychiatry, VA Medical Center, Ann Arbor, MI, USA
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32
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More JCA, Nistico R, Dolman NP, Clarke VRJ, Alt AJ, Ogden AM, Buelens FP, Troop HM, Kelland EE, Pilato F, Bleakman D, Bortolotto ZA, Collingridge GL, Jane DE. Characterisation of UBP296: a novel, potent and selective kainate receptor antagonist. Neuropharmacology 2004; 47:46-64. [PMID: 15165833 DOI: 10.1016/j.neuropharm.2004.03.005] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2003] [Revised: 02/23/2004] [Accepted: 03/01/2004] [Indexed: 10/26/2022]
Abstract
Willardiine derivatives with an N3-benzyl substituent bearing an acidic group have been synthesized with the aim of producing selective antagonists for GLUK5-containing kainate receptors. UBP296 was found to be a potent and selective antagonist of native GLUK5-containing kainate receptors in the spinal cord, with activity residing in the S enantiomer (UBP302). In cells expressing human kainate receptor subunits, UBP296 selectively depressed glutamate-induced calcium influx in cells containing GLUK5 in homomeric or heteromeric forms. In radioligand displacement binding studies, the willardiine analogues displaced [3H]kainate binding with IC50 values >100 microM at rat GLUK6, GLUK2 or GLUK6/GLUK2. An explanation of the GLUK5 selectivity of UBP296 was obtained using homology models of the antagonist bound forms of GLUK5 and GLUK6. In rat hippocampal slices, UBP296 reversibly blocked ATPA-induced depressions of synaptic transmission at concentrations subthreshold for affecting AMPA receptor-mediated synaptic transmission directly. UBP296 also completely blocked the induction of mossy fibre LTP, in medium containing 2 mM (but not 4 mM) Ca2+. These data provide further evidence for a role for GLUK5-containing kainate receptors in mossy fibre LTP. In conclusion, UBP296 is the most potent and selective antagonist of GLUK5-containing kainate receptors so far described.
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Affiliation(s)
- Julia C A More
- Department of Pharmacology, MRC Centre for Synaptic Plasticity, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, UK
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Haga KK, Gregory LJ, Hicks CA, Ward MA, Beech JS, Bath PW, Williams SCR, O'Neill MJ. The neuronal nitric oxide synthase inhibitor, TRIM, as a neuroprotective agent: effects in models of cerebral ischaemia using histological and magnetic resonance imaging techniques. Brain Res 2004; 993:42-53. [PMID: 14642829 DOI: 10.1016/j.brainres.2003.08.063] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Most neuroprotective compounds that appear promising in the pre-clinical phase of testing are subsequently dismissed as relatively ineffective when entered into large-scale clinical trials. Many pre-clinical studies of potential neuroprotective candidates evaluate efficacy in only one or possibly two different models of ischaemia. In this study we examined the effects of 1,2-trifluoromethylphenyl imidazole (TRIM), a novel neuronal nitric oxide synthase (nNOS) inhibitor, in three models of cerebral ischaemia (global gerbil, global rat and focal rat). In addition, to follow the progression of the pathology, we also compared traditional histology methods with more advanced magnetic resonance imaging (MRI) as endpoint measures for neurological damage and neuroprotection. TRIM (50 mg/kg i.p.) prevented ischaemia-induced hippocampal damage following global ischaemia in gerbils when administered before or immediately post-occlusion, but failed to protect when administration was delayed until 30 min post-occlusion. Further studies indicated that the compound (administered at 50 mg/kg, i.p., immediately after occlusion) also protected in a rat four-vessel occlusion (4-VO) model using both histological and diffusion-weighted (DW) imaging techniques. In a final study, TRIM (50 mg/kg i.p. 30 min after occlusion) provided a significant reduction in infarct volume at 4 and 24 h as measured using diffusion-weighted (DW) and proton density (PD)-weighted magnetic resonance imaging (MRI). This was confirmed using histological techniques. These studies confirm that nNOS inhibitors may have utility in stroke and provide evidence that combined magnetic resonance and histological methods can provide a powerful method of assessing neuronal damage in rodent models of cerebral ischaemia.
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Affiliation(s)
- Kristin K Haga
- Department of Clinical Neuroscience, University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, UK
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Zukin RS, Jover T, Yokota H, Calderone A, Simionescu M, Lau CG. Molecular and Cellular Mechanisms of Ischemia-Induced Neuronal Death. Stroke 2004. [DOI: 10.1016/b0-44-306600-0/50049-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Valgeirsson J, Nielsen EØ, Peters D, Varming T, Mathiesen C, Kristensen AS, Madsen U. 2-Arylureidobenzoic Acids: Selective Noncompetitive Antagonists for the Homomeric Kainate Receptor Subtype GluR5. J Med Chem 2003; 46:5834-43. [PMID: 14667236 DOI: 10.1021/jm030428j] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A series of 2-arylureidobenzoic acids (AUBAs) was prepared by a short and effective synthesis, and the pharmacological activity at glutamate receptors was evaluated in vitro and in vivo. The compounds showed noncompetitive antagonistic activity at the kainate receptor subtype GluR5. The most potent compounds showed more than 50-fold selectivity for GluR5 compared to GluR6 and the AMPA receptor subtypes GluR1-4. The structure-activity relationships for the AUBAs showed distinct structural requirements for the substituents on the two aromatic ring systems. Only para-substituents were tolerated on the benzoic acid moiety (ring A), whereas ring B tolerated a variety of substituents, but with a preference for lipophilic substituents. The most potent compounds had a 4-chloro substituent on ring A and 3-chlorobenzene (6b), 2-naphthalene (8h), or 2-indole (8k) as ring B and had IC(50) values of 1.3, 1.2, and 1.2 microM, respectively, in a functional GluR5 assay. Compound 6c (IC(50) = 4.8 microM at GluR5) showed activity in the in vivo ATPA rigidity test, indicating that 6c has better pharmacokinetic properties than 8h, which was inactive in this test. The AUBAs are the first example of a series of noncompetitive GluR5-selective antagonists and may prove to be important pharmacological tools and leads in the search for therapeutic glutamatergic agents.
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Affiliation(s)
- Jon Valgeirsson
- Department of Medicinal Chemistry, The Danish University of Pharmaceutical Sciences, 2 Universitetsparken, DK-2100 Copenhagen, Denmark
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Van Hemelrijck A, Vermijlen D, Hachimi-Idrissi S, Sarre S, Ebinger G, Michotte Y. Effect of resuscitative mild hypothermia on glutamate and dopamine release, apoptosis and ischaemic brain damage in the endothelin-1 rat model for focal cerebral ischaemia. J Neurochem 2003; 87:66-75. [PMID: 12969253 DOI: 10.1046/j.1471-4159.2003.01977.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The relationship between glutamate and dopamine release, apoptosis and ischaemic damage was studied following induction of transient focal cerebral ischaemia under normothermic (37 degrees C) and postischaemic (resuscitative) mild hypothermic (34 degrees C for 2 h) conditions in sevoflurane anaesthetized male Wistar rats. Focal ischaemia was induced by infusing endothelin-1 adjacent to the middle cerebral artery. In vivo microdialysis was used to sample glutamate and dopamine from striatum and parietal cortex of the ipsilateral hemisphere. The volume of ischaemic damage and the degree of apoptosis were determined 24 h after the insult. In both striatum and cortex of the normothermic group an initial increase in extracellular glutamate and dopamine levels following endothelin-1 infusion was observed. Striatal glutamate levels remained enhanced (250% of baseline) throughout the experiment, while the other neurotransmitter levels returned to baseline values. Hypothermia significantly attenuated the endothelin-1 induced glutamate release in the striatum. It also reduced apoptosis and infarct volume in the cortex. These results indicate that: (i) postischaemic mild hypothermia exerts its neuroprotective effect by inhibiting apoptosis in the ischaemic penumbral region; and (ii) this effect is not associated with an attenuation of glutamate or dopamine release in the cortex.
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Affiliation(s)
- An Van Hemelrijck
- Department of Pharmaceutical Chemistry and Drug Analysis, Vrije Universiteit Brussel, Brussels, Belgium
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Moyanova S, Kirov R, Kortenska L. Multi-unit activity suppression and sensorimotor deficits after endothelin-1-induced middle cerebral artery occlusion in conscious rats. J Neurol Sci 2003; 212:59-67. [PMID: 12810000 DOI: 10.1016/s0022-510x(03)00102-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Conscious Wistar rats with stereotaxically and unilaterally implanted cannula just above the middle cerebral artery (MCA) were injected with the powerful vasoconstrictor peptide endothelin-1 (ET1, 60 pmol in 3 microl). The purpose was to examine the long-term (from the 1st to the 14th day) changes in neuronal bioelectrical activity together with sensorimotor deficits after ET1-induced MCA occlusion (MCAO). Extracellular multi-unit activity (MUA) recorded from the ipsilateral fronto-parietal cortical area (supplied by MCA) and sensorimotor behavior (one postural reflex test and six limb placing tests) were examined. A significant suppression of the multi-unit activity was observed until the 14th day post-ET1. The rats exhibited significant unilateral sensorimotor deficits with a maximum at the 3-7 days after ET1 and a spontaneous partial recovery by days 11-14. A significant correlation was found between the suppression of the multi-unit activity and the sensorimotor deficits between the 3rd and the 10th day post-ET1. The results suggest that studying the bioelectrical activity in combination with the behavioral sensorimotor functions may be of use to assess the functional disturbances associated with focal cerebral ischemia and would help to examine the therapeutic benefits of various cerebroprotective treatments before initiating human clinical trials.
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Affiliation(s)
- Slavianka Moyanova
- Institute of Physiology, Bulgarian Academy of Sciences, Acad. G. Bonchev Str. 23, 1113 Sofia, Bulgaria.
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Pringle AK, Schmidt W, Deans JK, Wulfert E, Reymann KG, Sundstrom LE. 7-Hydroxylated epiandrosterone (7-OH-EPIA) reduces ischaemia-induced neuronal damage both in vivo and in vitro. Eur J Neurosci 2003; 18:117-24. [PMID: 12859344 DOI: 10.1046/j.1460-9568.2003.02734.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Recent evidence suggests that steroids such as oestradiol reduce ischaemia-induced neurodegeneration in both in vitro and in vivo models. A cytochrome P450 enzyme termed cyp7b that 7-hydroxylates many steroids is expressed at high levels in brain, although the role of 7-hydroxylated steroids is unknown. We have tested the hypothesis that the steroid-mediated neuroprotection is dependent on the formation of 7-hydroxy metabolites. Organotypic hippocampal slice cultures were prepared from Wistar rat pups and maintained in vitro for 14 days. Cultures were then exposed to 3 h hypoxia and neuronal damage assessed 24 h later using propidium iodide fluorescence as a marker of cell damage. Neurodegeneration occurred primarily in the CA1 pyramidal cell layer. The steroids oestradiol, dehydroepiandrosterone and epiandrosterone (EPIA) were devoid of neuroprotective efficacy when present at 100 nM pre-, during and post-hypoxia. The 7-hydroxy metabolites of EPIA, 7alpha-OH-EPIA and 7beta-OH-EPIA significantly reduced neurotoxicity at 100 nM and 10 nM. 7beta-OH-EPIA was also neuroprotective in two in vivo rat models of cerebral ischaemia: 0.1 mg/kg 7beta-OH-EPIA significantly reduced hippocampal cell loss in a model of global forebrain ischaemia, whereas 0.03 mg/kg was neuroprotective in a model of focal ischaemia even when administration was delayed until 6 h after the onset of ischaemia. Taken together, these data demonstrate that 7-hydroxylation of steroids confers neuroprotective efficacy, and that 7beta-OH-epiandrosterone represents a novel class of neuroprotective compounds with potential for use in acute neurodegenerative diseases.
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Affiliation(s)
- Ashley K Pringle
- Centre for Neurosciences, University of Southampton, Biomedical Sciences Building, Bassett Crescent East, Southampton SO16 7PX, UK.
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Affiliation(s)
- Juan Lerma
- Instituto Cajal, Consejo Superior de Investigaciones Científicas, Av. Doctor Arce 37, 28002 Madrid, Spain.
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Bortolotto ZA, Lauri S, Isaac JTR, Collingridge GL. Kainate receptors and the induction of mossy fibre long-term potentiation. Philos Trans R Soc Lond B Biol Sci 2003; 358:657-66. [PMID: 12740111 PMCID: PMC1693169 DOI: 10.1098/rstb.2002.1216] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
There is intense interest in understanding the molecular mechanisms involved in long-term potentiation (LTP) in the hippocampus. Significant progress in our understanding of LTP has followed from studies of glutamate receptors, of which there are four main subtypes (alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA), N-methyl-D-aspartate (NMDA), mGlu and kainate). This article summarizes the evidence that the kainate subtype of glutamate receptor is an important trigger for the induction of LTP at mossy fibre synapses in the CA3 region of the hippocampus. The pharmacology of the first selective kainate receptor antagonists, in particular the GLU(K5) subunit selective antagonist LY382884, is described. LY382884 selectively blocks the induction of mossy fibre LTP, in response to a variety of different high-frequency stimulation protocols. This antagonist also inhibits the pronounced synaptic facilitation of mossy fibre transmission that occurs during high-frequency stimulation. These effects are attributed to the presence of presynaptic GLU(K5)-subunit-containing kainate receptors at mossy fibre synapses. Differences in kainate receptor-dependent synaptic facilitation of AMPA and NMDA receptor-mediated synaptic transmission are described. These data are discussed in the context of earlier reports that glutamate receptors are not involved in mossy fibre LTP and more recent experiments using kainate receptor knockout mice, that argue for the involvement of GLU(K6) but not GLU(K5) kainate receptor subunits. We conclude that activation of presynaptic GLU(K5)-containing kainate receptors is an important trigger for the induction of mossy fibre LTP in the hippocampus.
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Affiliation(s)
- Zuner A Bortolotto
- MRC Centre for Synaptic Plasticity, Department of Anatomy, School of Medical Sciences, University Walk, Bristol BS8 1TD, UK
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41
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Ghersi C, Bonfanti A, Manzari B, Feligioni M, Raiteri M, Pittaluga A. Pharmacological heterogeneity of release-regulating presynaptic AMPA/kainate receptors in the rat brain: study with receptor antagonists. Neurochem Int 2003; 42:283-92. [PMID: 12470701 DOI: 10.1016/s0197-0186(02)00129-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Presynaptic alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA)/kainate receptors mediating hippocampal [(3)H]noradrenaline or [(3)H]serotonin release, striatal [(3)H]dopamine release and cortical [(3)H]acetylcholine release were pharmacologically characterized using several AMPA/kainate receptor antagonists. The releases of the four transmitters elicited by exposing synaptosomes to AMPA were antagonized by NBQX, indicating that they reflect AMPA/kainate receptor activation. GYKI52466 did not inhibit the AMPA-induced release of [(3)H]noradrenaline, [(3)H]dopamine or [(3)H]serotonin, while it weakly affected the AMPA-mediated release of [(3)H]acetylcholine. On the contrary, LY300164 and LY303070 were potent antagonists able to discriminate among AMPA/kainate receptor subtypes. Both compounds blocked the AMPA receptors mediating [(3)H]dopamine and [(3)H]acetylcholine release. However, LY303070, but not LY300164, inhibited the AMPA-induced release of [(3)H]noradrenaline, while the AMPA-mediated [(3)H]serotonin release was sensitive to LY300164 but not to LY303070. SYM2206 mimicked LY300164 and prevented the AMPA-induced release of [(3)H]dopamine, [(3)H]acetylcholine and [(3)H]serotonin, but not that of [(3)H]noradrenaline. NS102 failed to antagonize the AMPA-induced release of all four transmitters. LY293558 prevented the AMPA-mediated release of [(3)H]noradrenaline, [(3)H]dopamine, [(3)H]acetylcholine or [(3)H]serotonin. Differently, LY377770 did not inhibit the AMPA-mediated release of [(3)H]noradrenaline and [(3)H]acetylcholine, but it potently blocked the AMPA-induced release of [(3)H]serotonin and, less so, of [(3)H]dopamine. AMOA inhibited the AMPA-induced release of [(3)H]serotonin or [(3)H]acetylcholine, but not that of [(3)H]noradrenaline or [(3)H]dopamine. GAMS prevented the AMPA-mediated release of [(3)H]acetylcholine and, more weakly, that of [(3)H]dopamine, but it failed to inhibit the release of [(3)H]noradrenaline or [(3)H]serotonin elicited by AMPA. gamma-DGG did not affect the AMPA-mediated release of any of the four transmitters studied. In conclusion, based on the antagonist profiles obtained, the four receptors here analyzed all belong to the AMPA-preferring subclass of glutamate receptors; however, they appear to differ from each other, probably due to differences in subunit composition. The compounds LY300164, LY303070, LY377770, AMOA and GAMS may be useful to discriminate among AMPA-preferring receptor subtypes.
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Affiliation(s)
- Chiara Ghersi
- Sezione di Farmacologia e Tossicologia, Dipartimento di Medicina Sperimentale, Università di Genova, Italy
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Mrsić-Pelcić J, Zupan G, Maysinger D, Pelcić G, Vitezić D, Simonić A. The influence of MK-801 on the hippocampal free arachidonic acid level and Na+,K+-ATPase activity in global cerebral ischemia-exposed rats. Prog Neuropsychopharmacol Biol Psychiatry 2002; 26:1319-26. [PMID: 12502020 DOI: 10.1016/s0278-5846(02)00296-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The influence of 20 min global cerebral ischemia on the free arachidonic acid (FAA) level and Na+,K+-ATPase activity in the rat hippocampus at different time points after ischemia was examined. In addition, the effect of MK-801 on mentioned parameters was studied. Animals were exposed to 20 min global cerebral ischemia and were sacrificed immediately, 0.5, 1, 2, 6, 24, 48, 72, and 168 h after ischemic procedure. The level of the FAA and the Na+,K+-ATPase activity was measured during all reperfusion periods examined. Various doses of MK-801 (0.3, 1.0, 3.0, and 5.0 mg/kg) had been injected 30 min before ischemic procedure started. It was found that 20 min global cerebral ischemia induces a statistically significant increase of the FAA level immediately after ischemia and during the first 0.5 h of reperfusion. After a transient decrease, the level of FAA level increased again after 24 and 168 h of recirculation. Treatment with 3.0 mg/kg of MK-801 significantly prevented the FAA accumulation immediately and 0.5 h after ischemic insult while application of 5.0 mg/kg of MK-801 exerted a protective effect during the first 24 h. Global cerebral ischemia induces the significant decline in the Na+,K+-ATPase activity in the hippocampus starting from 1 to 168 h of reperfusion. Maximal inhibition was obtained 24 h after the ischemic damage. Application of 3.0 mg/kg of MK-801 exerted statistically significant protection during the first 24 h while the treatment with 5.0 mg/kg of MK-801 prevented fall in enzymatic activity during all reperfusion periods examined. Our results suggest that, in spite of different and complex pathophysiological mechanisms involved in the increase of FAA level and the decrease of the Na+,K+-ATPase activity, blockade of NMDA receptor subtype provides a very important strategy for the treatment of the postischemic excitotoxicity.
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Affiliation(s)
- Jasenka Mrsić-Pelcić
- Department of Pharmacology, School of Medicine, University of Rijeka, Brace Branchetta 20/1, 51000 Rijeka, Croatia.
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Ritz MF, Schmidt P, Mendelowitsch A. 17beta-estradiol effect on the extracellular concentration of amino acids in the glutamate excitotoxicity model in the rat. Neurochem Res 2002; 27:1677-83. [PMID: 12515322 DOI: 10.1023/a:1021695213099] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Estrogen has demonstrated a neuroprotective role in a rat model of glutamate excitotoxicity and other neurodegenerative disorders. We studied the effect of 17beta-estradiol on glutamate-induced increases in amino acids levels (aspartate, histidine, taurine and GABA) in the rat cortex. Local perfusion of glutamate produced a transient increase of aspartate, histidine, taurine and GABA in the extracellular fluid. Pretreatment with 17beta-estradiol significantly reduced the increases of taurine and moderately attenuated that of histidine, whereas aspartate and GABA releases were not modified. The effect of 17beta-estradiol on histidine release was reversed by the antiestrogen tamoxifen, suggesting a receptor-dependent mechanism. Good correlations between the volumes of the glutamate-induced lesions and the extracellular concentrations of taurine and aspartate were observed. These findings suggest that the attenuation of the glutamate-induced release of taurine by 17beta-estradiol may participate in the neuroprotective effects of 17beta-estradiol and that increased levels of aspartate and taurine are markers for the severity of the glutamate-induced cortical lesions.
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Smolders I, Bortolotto ZA, Clarke VRJ, Warre R, Khan GM, O'Neill MJ, Ornstein PL, Bleakman D, Ogden A, Weiss B, Stables JP, Ho KH, Ebinger G, Collingridge GL, Lodge D, Michotte Y. Antagonists of GLU(K5)-containing kainate receptors prevent pilocarpine-induced limbic seizures. Nat Neurosci 2002; 5:796-804. [PMID: 12080343 DOI: 10.1038/nn880] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Developments in the molecular biology and pharmacology of GLU(K5), a subtype of the kainate class of ionotropic glutamate receptors, have enabled insights into the roles of this subunit in synaptic transmission and plasticity. However, little is known about the possible functions of GLU(K5)-containing kainate receptors in pathological conditions. We report here that, in hippocampal slices, selective antagonists of GLU(K5)-containing kainate receptors prevented development of epileptiform activity--evoked by the muscarinic agonist, pilocarpine--and inhibited the activity when it was pre-established. In conscious rats, these GLU(K5) antagonists prevented and interrupted limbic seizures induced by intra-hippocampal pilocarpine perfusion, and attenuated accompanying rises in extracellular L-glutamate and GABA. This anticonvulsant activity occurred without overt side effects. GLU(K5) antagonism also prevented epileptiform activity induced by electrical stimulation, both in vitro and in vivo. Therefore, we propose that subtype-selective GLU(K5) kainate receptor antagonists offer a potential new therapy for epilepsy.
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Affiliation(s)
- Ilse Smolders
- Department of Pharmaceutical Chemistry & Drug Analysis, Pharmaceutical Institute, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium
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Blockade of striatal adenosine A2A receptor reduces, through a presynaptic mechanism, quinolinic acid-induced excitotoxicity: possible relevance to neuroprotective interventions in neurodegenerative diseases of the striatum. J Neurosci 2002. [PMID: 11880527 DOI: 10.1523/jneurosci.22-05-01967.2002] [Citation(s) in RCA: 156] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The aim of the present study was to evaluate whether, and by means of which mechanisms, the adenosine A2A receptor antagonist SCH 58261 [5-amino-7-(2-phenylethyl)-2-(2-furyl)-pyrazolo[4,3-e]-1,2,4-triazolo[1,5-c]pyrimidine] exerted neuroprotective effects in a rat model of Huntington's disease. In a first set of experiments, SCH 58261 (0.01 and 1 mg/kg) was administered intraperitoneally to Wistar rats 20 min before the bilateral striatal injection of quinolinic acid (QA) (300 nmol/1 microl). SCH 58261 (0.01 but not 1 mg/kg, i.p.) did reduce significantly the effects of QA on motor activity, electroencephalographic changes, and striatal gliosis. Because QA acts by both increasing glutamate outflow and directly stimulating NMDA receptors, a second set of experiments was performed to evaluate whether SCH 58261 acted by preventing the presynaptic and/or the postsynaptic effects of QA. In microdialysis experiments in naive rats, striatal perfusion with QA (5 mm) enhanced glutamate levels by approximately 500%. Such an effect of QA was completely antagonized by pretreatment with SCH 58261 (0.01 but not 1 mg/kg, i.p.). In primary striatal cultures, bath application of QA (900 microm) significantly increased intracellular calcium levels, an effect prevented by the NMDA receptor antagonist MK-801 [(+)-5-methyl-10,11-dihydro-5H-dibenzo [a,d] cyclohepten-5,10-imine maleate]. In this model, bath application of SCH 58261 (15-200 nm) tended to potentiate QA-induced calcium increase. We conclude the following: (1) the adenosine A2A receptor antagonist SCH 58261 has neuroprotective effects, although only at low doses, in an excitotoxic rat model of HD, and (2) the inhibition of QA-evoked glutamate outflow seems to be the major mechanism underlying the neuroprotective effects of SCH 58261.
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Pintor A, Quarta D, Pèzzola A, Reggio R, Popoli P. SCH 58261 (an adenosine A(2A) receptor antagonist) reduces, only at low doses, K(+)-evoked glutamate release in the striatum. Eur J Pharmacol 2001; 421:177-80. [PMID: 11516434 DOI: 10.1016/s0014-2999(01)01058-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The aim of the present work was to determine whether systemic administration of the adenosine A(2A) receptor antagonist, SCH 58261 (7-(2-phenylethyl)-5-amino-2-(2-furyl)-pyrazolo-[4,3-e]-1,2,4,triazolo[1,5-c]pyrimidine), could modulate striatal glutamate outflow in the rat. Microdialysis experiments were performed in male Wistar rats implanted with microdialysis probes in the striatum. Pretreatment (15 min before) with SCH 58261 (0.01 and 0.1, but not 1 mg/kg intraperitoneally) significantly prevented K(+)-stimulated glutamate release. These results suggest that SCH 58261 could possess neuroprotective effects in the low dose range, while, at higher doses, the occurrence of additional mechanisms may limit the neuroprotective potential of this drug.
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Affiliation(s)
- A Pintor
- Department of Pharmacology, Istituto Superiore di Sanità, Viale Regina Elena, 299, 00161, Rome, Italy
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Carpenedo R, Pittaluga A, Cozzi A, Attucci S, Galli A, Raiteri M, Moroni F. Presynaptic kynurenate-sensitive receptors inhibit glutamate release. Eur J Neurosci 2001; 13:2141-7. [PMID: 11422455 DOI: 10.1046/j.0953-816x.2001.01592.x] [Citation(s) in RCA: 170] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Kynurenic acid is a tryptophan metabolite provided with antagonist activity on ionotropic glutamate and alpha7 nicotinic acetylcholine receptors. We noticed that in rats with a dialysis probe placed in the head of their caudate nuclei, local administration of kynurenic acid (30-100 nM) significantly reduced glutamate output. Qualitatively and quantitatively similar effects were observed after systemic administration of kynurenine hydroxylase inhibitors, a procedure able to increase brain kynurenate concentrations. Interestingly, in microdialysis studies, methyllycaconitine (0.3-10 nM), a selective alpha7 nicotinic receptor antagonist, also reduced glutamate output. In isolated superfused striatal synaptosomes, kynurenic acid (100 nM), but not methyllycaconitine, inhibited the depolarization (KCl 12.5 mM)-induced release of transmitter or previously taken-up [3H]-D-aspartate. This inhibition was not modified by glycine, N-methyl-D-aspartate or subtype-selective kainate receptor agents, while CNQX or DNQX (10 microM), two AMPA and kainate receptor antagonists, reduced kynurenic acid effects. Low concentrations of kynurenic acid, however, did not modify [3H]-kainate (high and low affinity) or [3H]-AMPA binding to rat brain membranes. Finally, because metabotropic glutamate (mGlu) receptors modulate transmitter release in striatal preparations, we evaluated, with negative results, kynurenic acid (1-100 nM) effects in cells transfected with mGlu1, mGlu2, mGlu4 or mGlu5 receptors. In conclusion, our data show that kynurenate-induced inhibition of glutamate release is not mediated by glutamate receptors. Nicotinic acetylcholine receptors, however, may contribute to the inhibitory effects of kynurenate found in microdialysis studies, but not in those found in isolated synaptosomes.
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Affiliation(s)
- R Carpenedo
- Department of Preclinical and Clinical Pharmacology, Viale Pieraccini 6, University of Florence, 50139 Florence, Italy
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O'Neill MJ, Hicks CA, Ward MA, Osborne DJ, Wishart G, Mathews KS, McLaughlin DP, Stamford JA, McCarty DR, Patrick KE, Roman C, Fleisch JH, Gilmore J, Boot JR. LY393615, a novel neuronal Ca(2+) and Na(+) channel blocker with neuroprotective effects in models of in vitro and in vivo cerebral ischemia. Brain Res 2001; 888:138-149. [PMID: 11146060 DOI: 10.1016/s0006-8993(00)03043-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In the present studies we have examined the effects of a new calcium channel blocker, LY393615 ((N-Butyl-[5,5-bis-(4-fluorophenyl)tetrahydrofuran-2-yl]methylamine hydrochloride, NCC1048) in a model of hypoxia-hypoglycaemia in vitro and in a gerbil model of global and in two rat models of focal cerebral ischaemia in vivo. Results indicated that LY393615 protected against hypoxia-hypoglycaemic insults in brain slices and also provided significant protection against ischaemia-induced hippocampal damage in gerbil global cerebral ischaemia when dosed at 10, 12.5 (P<0.05) or 15 mg/kg i.p. (P<0.01) 30 min before and 2 h 30 min after occlusion. The compound penetrated the brain well after a 15 mg/kg i.p. dose and had a half-life of 2.5 h. In further studies LY393615 was protective 1 h post-occlusion when administered at 15 mg/kg i.p. followed by 2 doses of 5 mg/kg i.p. 2 and 3 h later. LY393615 dosed at 15 mg/kg i.p. followed by 2 further doses of 5 mg/kg i.p. (2 and 3 h later) also produced a significant reduction in the infarct volume following Endothelin-1 (Et-1) middle cerebral artery occlusion in the rat when administration was initiated immediately (P<0.01) or 1 h (P<0.05) after occlusion. The compound was also evaluated in the intraluminal monofilament model of focal ischaemia. The animals had the middle cerebral artery occluded for 2 h, and 15 min after reperfusion LY393615 was administered at 15 mg/kg i.p. followed by 2 mg/kg/h i.v. infusion for 6 h. There was no reduction in infarct volume using this dosing protocol. In conclusion, in the present studies we have reported that a novel calcium channel blocker, LY393615, with good bioavailability protects against neuronal damage caused by hypoxia-hypoglycaemia in vitro and both global and focal cerebral ischaemia in vivo. The compound is neuroprotective when administered post-occlusion and may therefore be a useful anti-ischaemic agent.
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Affiliation(s)
- M J O'Neill
- Lilly Research Centre Ltd., Erl Wood Manor, Windlesham, GU20 6PH, Surrey, UK.
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49
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Hicks CA, Ward MA, O'Neill MJ. Neuroprotective effects of the neuronal Ca(2+) channel blockers, LY042826 and LY393615 in vivo. Eur J Pharmacol 2000; 408:241-8. [PMID: 11090640 DOI: 10.1016/s0014-2999(00)00784-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
In the present studies, we have examined the effects of two new Ca(2+) channel blockers, LY042826 (N-[2-[(2-methylphenyl)(phenyl)methoxy]ethyl]-1-butanamine hydrochloride) and LY393615 (N-[[5, 5-bis(4-fluorophenyl)tetrahydro-2-furanyl]methyl]-1-butanamine hydrochloride) in the gerbil model of global and the endothelin-1 rat model of focal cerebral ischaemia in vivo. Results indicated that both LY042826 (P<0.01) and LY393615 (P<0.001) provided significant protection against ischaemia-induced hippocampal damage in global cerebral ischaemia when dosed at 15 mg/kg i.p. 30 min before and 2 h 30 min after occlusion. In further studies, LY042826 (P<0.05) and LY393615 (P<0.01) were also protective when administered at 15 mg/kg i.p. immediately after and 3 h post-occlusion. Both compounds also provided a significant reduction in the infarct volume following endothelin-1 middle cerebral artery occlusion in the rat when administered at 15 mg/kg i.p. immediately (P<0.05) after occlusion. This protection was similar to that observed with the NMDA receptor antagonist (5R,10S)-(+)-5-methyl-10, 11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine), MK-801 in this model. In conclusion and as a result of the present studies, we report that the novel Ca(2+) channel blockers, LY042826 and LY393615 protect against ischaemia-induced brain injury in gerbils and rats. The compounds were neuroprotective when administered post-occlusion and may therefore be useful anti-ischaemic agents.
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Affiliation(s)
- C A Hicks
- Eli Lilly and Co. Ltd., Lilly Research Centre, Erl Wood Manor, Surrey GU20 6PH, Windlesham, UK
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50
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O'Neill MJ, Murray TK, McCarty DR, Hicks CA, Dell CP, Patrick KE, Ward MA, Osborne DJ, Wiernicki TR, Roman CR, Lodge D, Fleisch JH, Singh J. ARL 17477, a selective nitric oxide synthase inhibitor, with neuroprotective effects in animal models of global and focal cerebral ischaemia. Brain Res 2000; 871:234-44. [PMID: 10899290 DOI: 10.1016/s0006-8993(00)02471-9] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In the present studies, we have evaluated the effects of N-[4-(2-¿[(3-Chlorophenyl)methyl]amino¿ethyl)phenyl]-2-thiophenecarbo ximidamide dihydrochloride (ARL 17477) on recombinant human neuronal NOS (nNOS) and endothelial NOS (eNOS). We then carried out pharmacokinetic studies and measured cortical nitric oxide synthase (NOS) inhibition to determine that the compound crossed the blood brain barrier. Finally, the compound was evaluated in a model of global ischaemia in the gerbil and two models of transient focal ischaemia in the rat. The IC(50) values for ARL 17477 on human recombinant human nNOS and eNOS were 1 and 17 microM, respectively. ARL 17477 (50 mg/kg i.p.) produced a significant reduction in the ischaemia-induced hippocampal damage following global ischaemia when administered immediately post-occlusion, but failed to protect when administration was delayed until 30 min post-occlusion. In the endothelin-1 model of focal ischaemia, ARL 17477 (1 mg/kg i.v.) significantly attenuated the infarct volume when administered at either 0, 1 or 2 h post-endothelin-1 (P<0.05). In the intraluminal suture model, ARL 17477 at both 1 and 3 mg/kg i.v. failed to reduce the infarct volume measured at 1, 3 or 7 days post-occlusion. These results demonstrate that ARL 17477 protects against global ischaemia in gerbils and provides some reduction in infarct volume following transient middle cerebral artery occlusion in rats, indicating that nNOS inhibition may be a useful treatment of ischaemic conditions.
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Affiliation(s)
- M J O'Neill
- Eli Lilly and Co. Ltd., Lilly Research Centre, Erl Wood Manor, Windlesham, GU20 6PH, Surrey, UK.
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