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Yan W, Zhang M, Yu Y, Yi X, Guo T, Hu H, Sun Q, Chen M, Xiong H, Chen L. Blockade of voltage-gated potassium channels ameliorates diabetes-associated cognitive dysfunction in vivo and in vitro. Exp Neurol 2019; 320:112988. [PMID: 31254519 DOI: 10.1016/j.expneurol.2019.112988] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 03/29/2019] [Accepted: 06/25/2019] [Indexed: 12/12/2022]
Abstract
The voltage-gated potassium (Kv) channel blockers tetraethylammonium (TEA) and 4-aminopyridine (4-AP) have shown beneficial effects on some neurological disorders. But their involvements in diabetes-associated cognitive dysfunction are still unknown. The present study aims to investigate whether the blockade of Kv channels by TEA and 4-AP alleviate cognitive decline in diabetes. In vivo, the effects of TEA and 4-AP (5 mg/kg body weight per day, 1 mg/kg body weight per day intraperitoneal injected for 4 weeks, respectively) were investigated in streptozotocin-induced C57BL/6 diabetic mice. In vitro study, we investigated the effects of TEA and 4-AP on the high glucose (HG) -stimulated primary cortical neurons. The results showed that TEA and 4-AP ameliorated the cognitive decline of diabetic mice in the Morris water maze test, improved the ultrastructure of pancreatic β cells, hippocampal neurons and synapses, decreased oxidative stress, modulated apoptosis-related proteins, and activated phosphatidylinositol 3-kinase (PI3K)/ Protein kinase-B (PKB or Akt) signaling pathway. In the HG-stimulated primary cultured cortical neurons, TEA and 4-AP increased the cell viability, decreased oxidative stress; prevented apoptosis and activated PI3K/Akt signaling pathway. Additionally, the PI3K inhibitor LY294002 partially abolished the effects of TEA and 4-AP. These findings indicate that the blockade of Kv channels by TEA and 4-AP ameliorates the diabetes-associated cognitive dysfunction via PI3K/Akt pathway, suggesting that targeting Kv channels could be a promising strategy for the treatments of cognitive impairments in diabetes.
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Affiliation(s)
- Wenhui Yan
- Department of Pharmacology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an 710061, Shaanxi, China
| | - Meng Zhang
- Department of Pharmacology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an 710061, Shaanxi, China
| | - Ye Yu
- Department of Pharmacology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an 710061, Shaanxi, China
| | - Xinyao Yi
- Department of Pharmacology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an 710061, Shaanxi, China
| | - Tingli Guo
- Department of Pharmacology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an 710061, Shaanxi, China
| | - Hao Hu
- Department of Pharmacology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an 710061, Shaanxi, China
| | - Qiang Sun
- Department of Pharmacology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an 710061, Shaanxi, China
| | - Mingxia Chen
- Electron Microscopy Room, Xi'an Jiaotong University Health Science Center, Xi'an 710061, Shaanxi, China
| | - Huangui Xiong
- Neurophysiology Laboratory, Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198-5880, USA.
| | - Lina Chen
- Department of Pharmacology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an 710061, Shaanxi, China; Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education, Xi'an 710061, Shaanxi, China.
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2
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Lodge D, Watkins JC, Bortolotto ZA, Jane DE, Volianskis A. The 1980s: D-AP5, LTP and a Decade of NMDA Receptor Discoveries. Neurochem Res 2018; 44:516-530. [PMID: 30284673 PMCID: PMC6420420 DOI: 10.1007/s11064-018-2640-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 09/12/2018] [Accepted: 09/17/2018] [Indexed: 01/02/2023]
Abstract
In the 1960s and 70s, biochemical and pharmacological evidence was pointing toward glutamate as a synaptic transmitter at a number of distinct receptor classes, known as NMDA and non-NMDA receptors. The field, however, lacked a potent and highly selective antagonist to block these putative postsynaptic receptors. So, the discoveries in the early 1980s of d-AP5 as a selective NMDA receptor antagonist and of its ability to block synaptic events and plasticity were a major breakthrough leading to an explosion of knowledge about this receptor subtype. During the next 10 years, the role of NMDA receptors was established in synaptic transmission, long-term potentiation, learning and memory, epilepsy, pain, among others. Hints at pharmacological heterogeneity among NMDA receptors were followed by the cloning of separate subunits. The purpose of this review is to recognize the important contributions made in the 1980s by Graham L. Collingridge and other key scientists to the advances in our understanding of the functions of NMDA receptors throughout the central nervous system.
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Affiliation(s)
- D Lodge
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - J C Watkins
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - Z A Bortolotto
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - D E Jane
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - A Volianskis
- School of Clinical Sciences, University of Bristol, Bristol, UK.
- Centre for Neuroscience and Trauma, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
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3
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Klass A, Sánchez-Porras R, Santos E. Systematic review of the pharmacological agents that have been tested against spreading depolarizations. J Cereb Blood Flow Metab 2018; 38:1149-1179. [PMID: 29673289 PMCID: PMC6434447 DOI: 10.1177/0271678x18771440] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Spreading depolarization (SD) occurs alongside brain injuries and it can lead to neuronal damage. Therefore, pharmacological modulation of SD can constitute a therapeutic approach to reduce its detrimental effects and to improve the clinical outcome of patients. The major objective of this article was to produce a systematic review of all the drugs that have been tested against SD. Of the substances that have been examined, most have been shown to modulate certain SD characteristics. Only a few have succeeded in significantly inhibiting SD. We present a variety of strategies that have been proposed to overcome the notorious harmfulness and pharmacoresistance of SD. Information on clinically used anesthetic, sedative, hypnotic agents, anti-migraine drugs, anticonvulsants and various other substances have been compiled and reviewed with respect to the efficacy against SD, in order to answer the question of whether a drug at safe doses could be of therapeutic use against SD in humans.
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Affiliation(s)
- Anna Klass
- Neurosurgery Department, University of Heidelberg, Heidelberg, Germany
| | | | - Edgar Santos
- Neurosurgery Department, University of Heidelberg, Heidelberg, Germany
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4
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Carletti R, Tacconi S, Mugnaini M, Gerrard P. Receptor distribution studies. Curr Opin Pharmacol 2017; 35:94-100. [PMID: 28803835 DOI: 10.1016/j.coph.2017.07.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 07/23/2017] [Indexed: 12/18/2022]
Abstract
Receptor distribution studies have played a key role in the characterization of receptor systems (e.g. GABAB, NMDA (GluNRs), and Neurokinin 1) and in generating hypotheses to exploit these systems as potential therapeutic targets. Distribution studies can provide important information on the potential role of candidate receptors in normal physiology/disease and alert for possible adverse effects of targeting the receptors. Moreover, they can provide valuable information relating to quantitative target engagement (e.g. % receptor occupancy) to drive mechanistic pharmacokinetic/pharmacodynamic (PK/PD) hypotheses for compounds in the Drug Discovery process. Finally, receptor distribution and quantitative target engagement studies can be used to validate truly translational technologies such as PET ligands and pharmacoEEG paradigms to facilitate bridging of the preclinical/clinical interface and thus increase probability of success.
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Affiliation(s)
- Renzo Carletti
- Center of Drug Discovery & Development, Aptuit S.r.l., via Fleming 4, 37135 Verona, Italy.
| | - Stefano Tacconi
- Center of Drug Discovery & Development, Aptuit S.r.l., via Fleming 4, 37135 Verona, Italy
| | - Manolo Mugnaini
- Neuroscience Discovery, AbbVie Deutschland GmbH & Co. KG, Knollstraße 50, 67061 Ludwigshafen, Germany
| | - Philip Gerrard
- Center of Drug Discovery & Development, Aptuit S.r.l., via Fleming 4, 37135 Verona, Italy
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5
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Sacchi S, Novellis VD, Paolone G, Nuzzo T, Iannotta M, Belardo C, Squillace M, Bolognesi P, Rosini E, Motta Z, Frassineti M, Bertolino A, Pollegioni L, Morari M, Maione S, Errico F, Usiello A. Olanzapine, but not clozapine, increases glutamate release in the prefrontal cortex of freely moving mice by inhibiting D-aspartate oxidase activity. Sci Rep 2017; 7:46288. [PMID: 28393897 PMCID: PMC5385520 DOI: 10.1038/srep46288] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 03/15/2017] [Indexed: 12/18/2022] Open
Abstract
D-aspartate levels in the brain are regulated by the catabolic enzyme D-aspartate oxidase (DDO). D-aspartate activates NMDA receptors, and influences brain connectivity and behaviors relevant to schizophrenia in animal models. In addition, recent evidence reported a significant reduction of D-aspartate levels in the post-mortem brain of schizophrenia-affected patients, associated to higher DDO activity. In the present work, microdialysis experiments in freely moving mice revealed that exogenously administered D-aspartate efficiently cross the blood brain barrier and stimulates L-glutamate efflux in the prefrontal cortex (PFC). Consistently, D-aspartate was able to evoke L-glutamate release in a preparation of cortical synaptosomes through presynaptic stimulation of NMDA, mGlu5 and AMPA/kainate receptors. In support of a potential therapeutic relevance of D-aspartate metabolism in schizophrenia, in vitro enzymatic assays revealed that the second-generation antipsychotic olanzapine, differently to clozapine, chlorpromazine, haloperidol, bupropion, fluoxetine and amitriptyline, inhibits the human DDO activity. In line with in vitro evidence, chronic systemic administration of olanzapine induces a significant extracellular release of D-aspartate and L-glutamate in the PFC of freely moving mice, which is suppressed in Ddo knockout animals. These results suggest that the second-generation antipsychotic olanzapine, through the inhibition of DDO activity, increases L-glutamate release in the PFC of treated mice.
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Affiliation(s)
- Silvia Sacchi
- Dipartimento di Biotecnologie e Scienze della Vita, Università degli studi dell'Insubria, 21100, Varese, Italy.,The Protein Factory, Politecnico di Milano and Università degli studi dell'Insubria, 20131, Milano, Italy
| | - Vito De Novellis
- Department of Experimental Medicine, Section of Pharmacology, The Second University of Naples (SUN), 80138, Naples, Italy
| | - Giovanna Paolone
- Department of Medical Sciences, Section of Pharmacology, University of Ferrara and National Institute of Neuroscience, 44100, Ferrara, Italy
| | - Tommaso Nuzzo
- Laboratory of Behavioural Neuroscience, Ceinge Biotecnologie Avanzate, 80145, Naples, Italy.,Department of Environmental, Biological and Pharmaceutical Sciences and Technologies, Second University of Naples (SUN), 81100, Caserta, Italy
| | - Monica Iannotta
- Department of Experimental Medicine, Section of Pharmacology, The Second University of Naples (SUN), 80138, Naples, Italy
| | - Carmela Belardo
- Department of Experimental Medicine, Section of Pharmacology, The Second University of Naples (SUN), 80138, Naples, Italy
| | - Marta Squillace
- Laboratory of Behavioural Neuroscience, Ceinge Biotecnologie Avanzate, 80145, Naples, Italy
| | - Paolo Bolognesi
- Department of Medical Sciences, Section of Pharmacology, University of Ferrara and National Institute of Neuroscience, 44100, Ferrara, Italy
| | - Elena Rosini
- Dipartimento di Biotecnologie e Scienze della Vita, Università degli studi dell'Insubria, 21100, Varese, Italy.,The Protein Factory, Politecnico di Milano and Università degli studi dell'Insubria, 20131, Milano, Italy
| | - Zoraide Motta
- Dipartimento di Biotecnologie e Scienze della Vita, Università degli studi dell'Insubria, 21100, Varese, Italy
| | - Martina Frassineti
- Department of Medical Sciences, Section of Pharmacology, University of Ferrara and National Institute of Neuroscience, 44100, Ferrara, Italy
| | - Alessandro Bertolino
- Department of Basic Medical Science, Neuroscience and Sense Organs, University of Bari Aldo Moro, 70121, Bari, Italy
| | - Loredano Pollegioni
- Dipartimento di Biotecnologie e Scienze della Vita, Università degli studi dell'Insubria, 21100, Varese, Italy.,The Protein Factory, Politecnico di Milano and Università degli studi dell'Insubria, 20131, Milano, Italy
| | - Michele Morari
- Department of Medical Sciences, Section of Pharmacology, University of Ferrara and National Institute of Neuroscience, 44100, Ferrara, Italy
| | - Sabatino Maione
- Department of Experimental Medicine, Section of Pharmacology, The Second University of Naples (SUN), 80138, Naples, Italy
| | - Francesco Errico
- Laboratory of Behavioural Neuroscience, Ceinge Biotecnologie Avanzate, 80145, Naples, Italy.,Department of Molecular Medicine and Medical Biotechnology, University of Naples "Federico II", 80131, Naples, Italy
| | - Alessandro Usiello
- Laboratory of Behavioural Neuroscience, Ceinge Biotecnologie Avanzate, 80145, Naples, Italy.,Department of Environmental, Biological and Pharmaceutical Sciences and Technologies, Second University of Naples (SUN), 81100, Caserta, Italy
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6
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Mothet JP, Le Bail M, Billard JM. Time and space profiling of NMDA receptor co-agonist functions. J Neurochem 2015; 135:210-25. [DOI: 10.1111/jnc.13204] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Revised: 05/12/2015] [Accepted: 06/02/2015] [Indexed: 02/01/2023]
Affiliation(s)
- Jean-Pierre Mothet
- Team ‘Gliotransmission and Synaptopathies’; Aix-Marseille Université; CNRS; CRN2M UMR7286; Marseille France
| | - Matildé Le Bail
- Team ‘Gliotransmission and Synaptopathies’; Aix-Marseille Université; CNRS; CRN2M UMR7286; Marseille France
| | - Jean-Marie Billard
- Center of Psychiatry and Neuroscience; University Paris Descartes; Sorbonne Paris City; UMR 894; Paris France
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7
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POSTER COMMUNICATIONS. Br J Pharmacol 2012. [DOI: 10.1111/j.1476-5381.1992.tb16283.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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8
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Vinson PN, Conn PJ. Metabotropic glutamate receptors as therapeutic targets for schizophrenia. Neuropharmacology 2012; 62:1461-72. [PMID: 21620876 PMCID: PMC3189289 DOI: 10.1016/j.neuropharm.2011.05.005] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Revised: 05/02/2011] [Accepted: 05/08/2011] [Indexed: 01/13/2023]
Abstract
Treatment options for schizophrenia that address all symptom categories (positive, negative, and cognitive) are lacking in current therapies for this disorder. Compounds targeting the metabotropic glutamate (mGlu) receptors hold promise as a more comprehensive therapeutic alternative to typical and atypical antipsychotics and may avoid the occurrence of extrapyramidal side effects that accompany these treatments. Activation of the group II mGlu receptors (mGlu(2) and mGlu(3)) and the group I mGlu(5) are hypothesized to normalize the disruption of thalamocortical glutamatergic circuitry that results in abnormal glutamaterigic signaling in the prefrontal cortex (PFC). Agonists of mGlu(2) and mGlu(3) have demonstrated efficacy for the positive symptom group in both animal models and clinical trials with mGlu(2) being the subtype most likely responsible for the therapeutic effect. Limitations in the chemical space tolerated by the orthosteric site of the mGlu receptors has led to the pursuit of compounds that potentiate the receptor's response to glutamate by acting at less highly conserved allosteric sites. Several series of selective positive allosteric modulators (PAMs) for mGlu(2) and mGlu(5) have demonstrated efficacy in animal models used for the evaluation of antipsychotic agents. In addition, evidence from animal studies indicates that mGlu(5) PAMs hold promise for the treatment of cognitive deficits that occur in schizophrenia. Hopefully, further optimization of allosteric modulators of mGlu receptors will yield clinical candidates that will allow full evaluation of the potential efficacy of these compounds in the treatment of multiple symptom domains in schizophrenia patients in the near future.
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Affiliation(s)
- Paige N. Vinson
- Vanderbilt University Medical Center, Department of Pharmacology and Vanderbilt Center for Neuroscience Drug Discovery, Nashville, TN 37202
| | - P. Jeffrey Conn
- Vanderbilt University Medical Center, Department of Pharmacology and Vanderbilt Center for Neuroscience Drug Discovery, Nashville, TN 37202
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9
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Snyder MA, Cooke BM, Woolley CS. Estradiol potentiation of NR2B-dependent EPSCs is not due to changes in NR2B protein expression or phosphorylation. Hippocampus 2011; 21:398-408. [PMID: 20082293 DOI: 10.1002/hipo.20756] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The hormone, 17β-estradiol (E2), influences the structure and function of synapses in the CA1 region of the hippocampus. E2 increases the density of dendritic spines and excitatory synapses on CA1 pyramidal cells, increases CA1 cells' sensitivity to excitatory synaptic input mediated by the NMDA receptor (NMDAR), enhances NMDAR-dependent long-term potentiation, and improves hippocampus-dependent working memory. Smith and McMahon (2006 J Neurosci 26:8517-8522) reported that the larger NMDAR-mediated excitatory postsynaptic currents (EPSCs) recorded after E2 treatment are due primarily to an increased contribution of NR2B-containing NMDARs. We used a combination of electrophysiology, Western blot, and immunofluorescence to investigate two potential mechanisms by which E2 could enhance NR2B-dependent EPSCs: An increase in NMDAR subunit protein levels and/or a change(s) in NR2B phosphorylation. Our studies confirmed the E2-induced increase in NR2B-dependent EPSC amplitude, but we found no evidence that E2 affects protein levels for the NR1, NR2A, or NR2B subunit of the NMDAR, nor that E2 affects phosphorylation of NR2B. Our findings suggest that the effects of E2 on NMDAR-dependent synaptic physiology in the hippocampus likely result from recruitment of NR2B-containing NMDARs to synapses rather than from increased expression of NMDARs or changes in their phosphorylation state.
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Affiliation(s)
- Melissa A Snyder
- Department of Neurobiology and Physiology, Northwestern University, Evanston, Illinois, USA
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10
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Werkheiser J, Cowan A, Gomez T, Henry C, Parekh S, Chau S, Baron DA, Rawls SM. Icilin-induced wet-dog shakes in rats are dependent on NMDA receptor activation and nitric oxide production. Pharmacol Biochem Behav 2009; 92:543-8. [DOI: 10.1016/j.pbb.2009.02.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2008] [Revised: 02/04/2009] [Accepted: 02/13/2009] [Indexed: 01/22/2023]
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11
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Guard DB, Swartz TD, Ritter RC, Burns GA, Covasa M. Blockade of hindbrain NMDA receptors containing NR2 subunits increases sucrose intake. Am J Physiol Regul Integr Comp Physiol 2009; 296:R921-8. [PMID: 19193935 DOI: 10.1152/ajpregu.90456.2008] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have previously shown that blockade of N-methyl-d-aspartate (NMDA) receptors in the caudal brain stem delays satiation and increases food intake. NMDA receptors are heterodimers made up of distinct, but different, ion channel subunits. The NR2 subunits of the NMDA receptor contain the binding site for glutamate. About half of vagal afferents express immunoreactivity for NMDA NR2B subunit and about half of the NR2B expressing afferents also express NMDA NR2C or NR2D subunits. This suggests that increased food intake may be evoked by interference with glutamate binding to NMDA channels containing the NR2B subunit. To test this, we measured deprivation-induced intake of 15% sucrose solution following fourth ventricle and intra-nucleus of the solitary tract (intra-NTS) injections of Conantokin G (Con G; NR2B blocker), d-3-(2-carboxypiperazin-4-yl)-1-propenyl-1-phosphoric acid (d-CPPene; NR2B/2A blocker), and (+/-)-cis-1-(phenanthren-2yl-carbonyl)piperazine-2,3-dicarboxylic acid (PPDA; NR2D/C blocker). Fourth ventricular administration of Con G (5, 20, 40, 80 ng), d-CPPene (3.0, 6.25, 12.5, 25, 50, 100 ng), and PPDA (300, 400 ng) increased sucrose intake significantly compared with control. Likewise, injections of Con G (10 ng), d-CPPene (5 ng, 10 ng), and PPDA (0.5, 1.0, 2.5, 5.0 ng) directly into the NTS significantly increased sucrose intake. These results show that hindbrain injection of competitive NMDA antagonists with selectivity or preference for the NMDA receptor NR2B or NR2C subunits increases food intake.
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Affiliation(s)
- Douglas B Guard
- Department of Nutritional Sciences, College of Health and Human Development, The Pennsylvania State University, Univ. Park, PA 16802, USA
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12
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Zhang XL, Sullivan JA, Moskal JR, Stanton PK. A NMDA receptor glycine site partial agonist, GLYX-13, simultaneously enhances LTP and reduces LTD at Schaffer collateral-CA1 synapses in hippocampus. Neuropharmacology 2008; 55:1238-50. [PMID: 18796308 DOI: 10.1016/j.neuropharm.2008.08.018] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2008] [Revised: 07/18/2008] [Accepted: 08/04/2008] [Indexed: 11/30/2022]
Abstract
N-methyl-D-aspartate glutamate receptors (NMDARs) are a key route for Ca2+ influx into neurons important to both activity-dependent synaptic plasticity and, when uncontrolled, triggering events that cause neuronal degeneration and death. Among regulatory binding sites on the NMDAR complex is a glycine binding site, distinct from the glutamate binding site, which must be co-activated for NMDAR channel opening. We developed a novel glycine site partial agonist, GLYX-13, which is both nootropic and neuroprotective in vivo. Here, we assessed the effects of GLYX-13 on long-term synaptic plasticity and NMDAR transmission at Schaffer collateral-CA1 synapses in hippocampal slices in vitro. GLYX-13 simultaneously enhanced the magnitude of long-term potentiation (LTP) of synaptic transmission, while reducing long-term depression (LTD). GLYX-13 reduced NMDA receptor-mediated synaptic currents in CA1 pyramidal neurons evoked by low frequency Schaffer collateral stimulation, but enhanced NMDAR currents during high frequency bursts of activity, and these actions were occluded by a saturating concentration of the glycine site agonist d-serine. Direct two-photon imaging of Schaffer collateral burst-evoked increases in [Ca2+] in individual dendritic spines revealed that GLYX-13 selectively enhanced burst-induced NMDAR-dependent spine Ca2+ influx. Examining the rate of MK-801 block of synaptic versus extrasynaptic NMDAR-gated channels revealed that GLYX-13 selectively enhanced activation of burst-driven extrasynaptic NMDARs, with an action that was blocked by the NR2B-selective NMDAR antagonist ifenprodil. Our data suggest that GLYX-13 may have unique therapeutic potential as a learning and memory enhancer because of its ability to simultaneously enhance LTP and suppress LTD.
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Affiliation(s)
- Xiao-lei Zhang
- Department of Cell Biology & Anatomy, New York Medical College, Basic Sciences Building, Room 217, Valhalla, NY 10595, USA
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13
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Lodge D. The history of the pharmacology and cloning of ionotropic glutamate receptors and the development of idiosyncratic nomenclature. Neuropharmacology 2008; 56:6-21. [PMID: 18765242 DOI: 10.1016/j.neuropharm.2008.08.006] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2008] [Revised: 07/31/2008] [Accepted: 08/06/2008] [Indexed: 10/21/2022]
Abstract
In this article, the beginnings of glutamate pharmacology are traced from the early doubts about 'non-specific' excitatory effects, through glutamate- and aspartate-preferring receptors, to NMDA, quisqualate/AMPA and kainate subtypes, and finally to the cloning of genes for these receptor subunits. The development of selective antagonists, crucial to the subtype classification, allowed the fundamental importance of glutamate receptors to synaptic activity throughout the CNS to be realised. The ability to be able to express and manipulate cloned receptor subunits is leading to huge advances in our understanding of these receptors. Similarly the tortuous path of the nomenclature is followed from naming with reference to exogenous agonists, through abortive early attempts at generic schemes, and back to the NC-IUPHAR system based on the natural agonist, the defining exogenous agonist and the gene names.
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Affiliation(s)
- David Lodge
- MRC Centre for Synaptic Plasticity, Department of Anatomy, University of Bristol, University Walk, Bristol BS8 1TD, United Kingdom.
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14
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Difference in brain distributions of carbon 11-labeled 4-hydroxy-2(1H)-quinolones as PET radioligands for the glycine-binding site of the NMDA ion channel. Nucl Med Biol 2008; 35:203-12. [DOI: 10.1016/j.nucmedbio.2007.10.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2006] [Revised: 10/02/2007] [Accepted: 10/17/2007] [Indexed: 10/22/2022]
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15
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van Amsterdam FT, Giberti A, Mugnaini M, Ratti E. 3-[(±)-2-Carboxypiperazin-4-yl]propyl-1-Phosphonic Acid Recognizes Two N-Methyl-D-Aspartate Binding Sites in Rat Cerebral Cortex Membranes. J Neurochem 2006; 59:1850-5. [PMID: 1357101 DOI: 10.1111/j.1471-4159.1992.tb11019.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Binding of 3-[(+-)-2-carboxypiperazin-4-yl][3H]-propyl-1-phosphonic acid ([3H]CPP), a competitive inhibitor of N-methyl-D-aspartate (NMDA), has been studied in synaptic plasma membranes from rat cerebral cortex. Computer analysis of saturation and homologous displacement isotherms deriving from these plasma membranes indicated the existence of two binding sites: a specific, saturable, high-affinity binding site with a pKD value of 7.53 +/- 0.03 (29.5 nM) and a maximum binding value (Bmax) of 2.25 +/- 0.36 pmol/mg of protein, and a low-affinity site with a KD of approximately 600 nM and a Bmax of 7.0 pmol/mg of protein. It is argued that, in the light of current literature evidence, the low-affinity binding site may represent an agonist-dependent receptor, linked to physiological processes such as neurotransmitter release and channel regulation, whereas the high-affinity binding site may be linked to an antagonist-preferred receptor, for which no function has yet been reported.
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Affiliation(s)
- F T van Amsterdam
- Glaxo Research Laboratories, Department of Biochemistry, Verona, Italy
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Lee SY, Jang CG. Increases in [(3)H]-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor binding and mRNA expression of AMPA-sensitive glutamate receptor A (GluR-A) subunits in rats withdrawn from butorphanol. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2005; 68:2163-74. [PMID: 16326431 DOI: 10.1080/15287390500177263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
An autoradiographic study of [(3)H]-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid(AMPA) receptor binding and an assessment of in situ hybridization of AMPA-sensitive glutamate receptor A (GluR-A) subunits in the rat brain were performed 7 h after withdrawal from butorphanol infusion. Animals were rendered dependent by intracerebroventricular (icv) infusion of butorphanol (26 nmol/microl/h) via osmotic minipumps for 3 d. Brain sections for binding of [(3)H]AMPA were incubated with 15 nM [(3)H]AMPA. The probes for in situ hybridization were labeled at its 3 cent end using terminal deoxynucleotidyl transferase and [(35)S]dATP. The highest degree of [(3)H]AMPA binding was shown in the hippocampus. The extent of [(3)H]AMPA binding was increased significantly in each of the brain areas examined, cortex, septum, caudate putamen, and hippocampus of rats, following withdrawal from butorphanol. The highest level of mRNA for GluR-A receptor for flop and flip subunits, was found in the dentate gyrus and in the CA3 region of the hippocampus. The amounts of mRNA for the flop form of GluR-A receptor were significantly increased in the cortex, caudate putamen, thalamus, and dentate gyrus of hippocampus of rat brain. The amounts of mRNA for the flip form of GluR-A receptor were markedly elevated in the cortex, thalamus, caudate putamen, and hippocampus. These findings suggest that increases in expression of mRNA for the GluR-A receptor and in the binding of AMPA to its receptor may play an important role during withdrawal from butorphanol dependence.
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Affiliation(s)
- Seok-Yong Lee
- Department of Pharmacology, College of Pharmacy, Sungkyunkwan University, Suwon, Republic of Korea
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17
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Moskal JR, Kuo AG, Weiss C, Wood PL, O'Connor Hanson A, Kelso S, Harris RB, Disterhoft JF. GLYX-13: A monoclonal antibody-derived peptide that acts as an N-methyl-d-aspartate receptor modulator. Neuropharmacology 2005; 49:1077-87. [PMID: 16051282 DOI: 10.1016/j.neuropharm.2005.06.006] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2005] [Revised: 06/07/2005] [Accepted: 06/09/2005] [Indexed: 12/31/2022]
Abstract
We previously created a monoclonal antibody (MAb), B6B21, that acts as a partial agonist at the glycine site of the N-methyl-d-aspartate (NMDA) receptor [Moskal, J.R., Schaffner, A.E., 1986. Monoclonal antibodies to the dentate gyrus: immunocytochemical characterization and flow cytometric analysis of hippocampal neurons bearing a unique cell-surface antigen. J. Neurosci. 6, 2045-2053.]. The hypervariable region of the light chain of B6B21 was cloned and sequenced. Peptides were then synthesized based on this sequence information and screened using rat hippocampal membrane preparations to measure [(3)H]MK-801 binding in the presence of 7-chlorokynurenic acid, a glycine site-specific competitive inhibitor of NMDA receptor [Moskal, J.R., Yamamoto, H., Colley, P.A., 2001. The use of antibody engineering to create novel drugs that target N-methyl-d-aspartate receptors. Curr. Drug Targets 2, 331-345.]. Peptides that were able to increase [(3)H]MK-801 binding in a dose-dependent manner under these conditions were named Glyxins. Here we report that GLYX-13, a tetrapeptide (TPPT-amide), was found to readily cross the blood-brain barrier and modulate the NMDA receptor in a glycine-like fashion when examined pharmacologically and electrophysiologically. When GLYX-13 was administered to rats at 0.5-1.0mg/kg i.v., a significant enhancement in learning was observed using a hippocampus-dependent trace eye blink conditioning paradigm. These data indicate that the Glyxins are a new class of NMDA receptor modulators that may have therapeutic potential. Based on the broad agonist range in vitro and the potent cognitive-enhancing properties in a valid in vivo model of learning, GLYX-13 is a new drug candidate with potential for the treatment of cognitive disorders.
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MESH Headings
- Animals
- Antibodies, Monoclonal/blood
- Antibodies, Monoclonal/pharmacokinetics
- Antibodies, Monoclonal/pharmacology
- Blood-Brain Barrier
- Cerebellum/drug effects
- Cerebellum/metabolism
- Chromatography, High Pressure Liquid
- Cognition/drug effects
- Conditioning, Eyelid/drug effects
- Cycloserine/pharmacology
- Dose-Response Relationship, Drug
- Electrophysiology
- In Vitro Techniques
- Membrane Potentials/drug effects
- Oligopeptides/pharmacology
- Patch-Clamp Techniques
- Rats
- Rats, Inbred BN
- Rats, Inbred F344
- Receptors, Glycine/drug effects
- Receptors, N-Methyl-D-Aspartate/drug effects
- Xenopus laevis
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Affiliation(s)
- Joseph R Moskal
- Department of Biomedical Engineering, The Falk Center for Molecular Therapeutics, Northwestern University, 1801 Maple Avenue, Evanston, IL 60201, USA.
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18
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Blaise MC, Sowdhamini R, Pradhan N. Comparative analysis of different competitive antagonists interaction with NR2A and NR2B subunits of N-methyl-D-aspartate (NMDA) ionotropic glutamate receptor. J Mol Model 2005; 11:489-502. [PMID: 15928921 DOI: 10.1007/s00894-005-0258-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2004] [Accepted: 02/22/2005] [Indexed: 10/25/2022]
Abstract
The antagonist-bound conformation of the NR2A and NR2B subunits of N-methyl-D-aspartate (NMDA) ionotropic glutamate receptor are modeled using the crystal structure of the DCKA (5,7-dichloro-kynurenic acid)-bound form of the NR1 subunit ligand-binding core (S1S2). Five different competitive NMDA receptor antagonists [(1) DL-AP5; (2) DL-AP7; (3) CGP-37847; (4) CGP 39551; (5) (RS)-CPP] have been docked into both NR2A and NR2B subunits. Experimental studies report NR2A and NR2B subunits having dissimilar interactions and affinities towards the antagonists. However, the molecular mechanism of this difference remains unexplored. The distinctive features in the antagonist's interaction with these two different but closely related (approximately 80% sequence identity at this region) subunits are analyzed from the patterns of their hydrogen bonding. The regions directly involved in the antagonist binding have been classified into seven different interaction sites. Two conserved hydrophilic pockets located at both the S1 and S2 domains are found to be crucial for antagonist binding. The positively charged (Lys) residues present at the second interaction site and the invariant residue (Arg) located at the fourth interaction site are seen to influence ligand binding. The geometry of the binding pockets of NR2A and NR2B subunits have been determined from the distance between the C-alpha atoms in the residues interacting with the ligands. The binding pockets are found to be different for NR2A and NR2B. There are gross dissimilarities in competitive antagonist binding between these two subunits. The binding pocket geometry identified in this study may have the potential for future development of selective antagonists for the NR2A or NR2B subunit.
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Affiliation(s)
- Mathias-Costa Blaise
- Department of Psychopharmacology, National Institute of Mental Health and Neuro Sciences (NIMHANS), Bangalore, 560029, India
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19
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Kinarsky L, Feng B, Skifter DA, Morley RM, Sherman S, Jane DE, Monaghan DT. Identification of Subunit- and Antagonist-Specific Amino Acid Residues in theN-Methyl-d-aspartate Receptor Glutamate-Binding Pocket. J Pharmacol Exp Ther 2005; 313:1066-74. [PMID: 15743930 DOI: 10.1124/jpet.104.082990] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The resolved X-ray crystal structures of the glutamate-binding domain (S1/S2 domains) of the GluR2 and NR1 glutamate receptor subunits were used to model the homologous regions of the N-methyl-D-aspartate (NMDA) receptor's NR2 subunits. To test the predictive value of these models, all four stereoisomers of the antagonist 1-(phenanthren-2-carbonyl) piperazine-2,3-dicarboxylic acid (PPDA) were docked into the NR2B glutamate-binding site model. This analysis suggested an affinity order for the PPDA isomers of d-cis > L-cis > L-trans = D-trans and predicted that the 2-position carboxylate group of the cis-PPDA isomers, but not of the trans-PPDA isomers, may be interacting with histidine 486 in NR2B. Consistent with these predictions, cis-PPDA displays a 35-fold higher affinity for NR2B-containing NMDA receptors than trans-PPDA. In addition, mutating NR2B's H486 to phenylalanine decreased cis-PPDA affinity 8-fold but had no effect on trans-PPDA affinity. In contrast, the NR2B H486F mutation increased the affinity of the typical antagonists CGS-19755 [(2R*,4S*)-4-phosphonomethyl-2-piperidine carboxylic acid] and 4-(3-phosphonopropyl) piperidine-2-carboxylic acid. In the NR1-based NR2 models, there were only four subunit-specific amino acid residues exposed to the ligand-binding pocket (and six in the GluR2-based models). These residues are located at the edge of the binding pocket, suggesting that large antagonists may be necessary for subtype specificity. Of these residues, mutational analysis and modeling suggest that A414, R712, and G713 (NR2B numbering) may be especially useful for developing NR2C- and NR2D-selective NMDA receptor antagonists and that residues A414 and T428 may determine subunit variations in agonist affinity.
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Affiliation(s)
- Leo Kinarsky
- The Eppley Research Institute, University of Nebraska Medical Center, Omaha, 68198, USA
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20
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Mattson MP. Adventures in neural plasticity, aging, and neurodegenerative disorders aboard the CWC beagle. Neurochem Res 2004; 28:1631-7. [PMID: 14584817 DOI: 10.1023/a:1026000703290] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
This article recounts some of the scientific endeavors of Carl W. Cotman (CWC) during his journeys through the cellular circuitry of the mammalian brain. I have selected for consideration his findings that have been an important impetus for my own research; in several cases our different experiments have provided complementary data to support an hypothesis. Three examples are (i) Carl's studies of the roles of glutamate in synaptic transmission and plasticity in the adult brain and my studies of how glutamate regulates neurite outgrowth and cell survival in brain development; (ii) his and our studies of the mechanisms whereby amyloid beta-peptide damages and kills neurons; and (iii) Carl's evidence that physical activity regulates neurotrophin levels in the brain and our evidence that dietary restriction has similar effects and is neuroprotective. In case you have not yet realized how I chose a title for this article it is because Carl has a (very distant) connection with Charles Darwin-Darwin sailed on a vessel called the Beagle and Carl has studied beagle dogs, establishing them as a model for understanding the neurobiology of human brain aging.
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Affiliation(s)
- Mark P Mattson
- Laboratory of Neurosciences, National Institute on Aging Gerontology Research Center, 5600 Nathan Shock Drive, Baltimore, Maryland, USA.
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21
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Feng B, Tse HW, Skifter DA, Morley R, Jane DE, Monaghan DT. Structure-activity analysis of a novel NR2C/NR2D-preferring NMDA receptor antagonist: 1-(phenanthrene-2-carbonyl) piperazine-2,3-dicarboxylic acid. Br J Pharmacol 2004; 141:508-16. [PMID: 14718249 PMCID: PMC1574223 DOI: 10.1038/sj.bjp.0705644] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
(2S*,3R*)-1-(biphenyl-4-carbonyl)piperazine-2,3-dicarboxylic acid (PBPD) is a moderate affinity, competitive N-methyl-d-aspartate (NMDA) receptor antagonist with an atypical pattern of selectivity among NMDA receptor 2 subunit (NR2) subunits. We now describe the activity of several derivatives of PBPD tested at both rat brain NMDA receptors using l-[3H]-glutamate binding assays and at recombinant receptors expressed in Xenopus oocytes. Substituting various branched ring structures for the biphenyl group of PBPD reduced NMDA receptor activity. However, substituting linearly arranged ring structures - fluorenone or phenanthrene groups - retained or enhanced activity. Relative to PBPD, the phenanthrene derivative (2S*, 3R*)-1-(phenanthrene-2-carbonyl)piperazine-2,3-dicarboxylic acid (PPDA) displayed a 30- to 78-fold increase in affinity for native NMDA receptors. At recombinant receptors, PPDA displayed a 16-fold (NR2B) to 94-fold (NR2C) increase in affinity over PBPD. Replacement of the biphenyl group of PBPD with a 9-oxofluorene ring system resulted in small changes in receptor affinity and subtype selectivity. 2'-Bromo substitution on the biphenyl group of PBPD reduced antagonist affinity 3- to 5-fold at NR2A-, NR2B- and NR2D-containing receptors, but had little effect on NR2C-containing receptors. In contrast, 4'-fluoro substitution of the biphenyl ring of PBPD selectively increased NR2A affinity. The aromatic rings of PBPD and PPDA increase antagonist affinity and appear to interact with a region of the NMDA receptor displaying subunit heterogeneity. PPDA is the most potent and selective NR2C/NR2D-preferring antagonist yet reported and thus may be useful in defining NR2C/NR2D function and developing related antagonists with improved NMDA receptor subtype selectivity. British Journal of Pharmacology (2004) 141, 508-516. doi:10.1038/sj.bjp.0705644
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Affiliation(s)
- Bihua Feng
- Department of Pharmacology, University of Nebraska Medical Center, Omaha, NE 68198-6260, U.S.A
| | - Heong W Tse
- Department of Pharmacology, University of Bristol, Bristol BS8 1TD
| | - Donald A Skifter
- Department of Pharmacology, University of Nebraska Medical Center, Omaha, NE 68198-6260, U.S.A
| | - Richard Morley
- Department of Pharmacology, University of Bristol, Bristol BS8 1TD
| | - David E Jane
- Department of Pharmacology, University of Bristol, Bristol BS8 1TD
| | - Daniel T Monaghan
- Department of Pharmacology, University of Nebraska Medical Center, Omaha, NE 68198-6260, U.S.A
- Author for correspondence:
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22
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Chapman DE, Keefe KA, Wilcox KS. Evidence for functionally distinct synaptic NMDA receptors in ventromedial versus dorsolateral striatum. J Neurophysiol 2003; 89:69-80. [PMID: 12522160 DOI: 10.1152/jn.00342.2002] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
N-methyl-D-aspartate receptors (NMDARs) are comprised of different subunits. NR2 subunits confer different pharmacological and biophysical properties to NMDARs. Although NR2B subunit expression is uniform throughout striatum, NR2A subunit expression is greater laterally. Pharmacologically isolated NMDAR-mediated excitatory postsynaptic currents (NMDAR-EPSCs) were elicited using minimal local stimulation and recorded in the whole cell configuration to test the hypothesis that biophysical and pharmacological properties of NMDAR-EPSCs of striatal neurons would vary as a function of their location in adult rat striatum. We observed that the decay-time kinetics of NMDAR-EPSCs are significantly slower in neurons of ventromedial versus dorsolateral striatum. Whereas ifenprodil did not differentially affect NMDAR-EPSCs in these regions, application of either glycine or D-serine increased the peak current of NMDAR-EPSCs selectively in dorsolateral striatum. These data provide evidence for functionally distinct NMDARs in the same neuron type in the same brain region of the adult rodent brain. These data thus suggest that the nature of synaptic processing of excitatory input is different in the ventromedial and dorsolateral striatum of the adult rodent brain, regions differentially involved in limbic versus sensorimotor processes, respectively.
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Affiliation(s)
- David E Chapman
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Utah, Salt Lake City 84112, USA
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23
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Abstract
The beneficial effects of hypothermia have long been known in non-traditional medicine but it is only in the past few decades that studies on the neuroprotective effects of hypothermia in hypoxic-ischemic brain injury have begun. Different mechanisms have been put forward to explain hypothermic neuroprotection including reduction of the excessive release of the excitatory amino acid neurotransmitter, glutamate. Recent experiments have questioned the key role of this neurotoxin in hypoxic-ischemic neuropathogenesis. In contrast, a mediatory role for another neurotransmitter, glycine in the neuroprotective effects of hypothermia has become more attractive, along with an indication of its role in the pathogenesis of ischemic neuronal damage. Thus, on the basis of reviewing relevant literature the hypothesis of a glycine-related mechanism of hypothermic neuroprotection in ischemia-induced neuronal injury has been put forward.
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Affiliation(s)
- Giuli Kvrivishvili
- Department of Anatomy, School of Veterinary Sciences, Southwell Street, Bristol BS2 8EJ, UK.
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24
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Svingos AL, Colago EEO. Kappa-Opioid and NMDA glutamate receptors are differentially targeted within rat medial prefrontal cortex. Brain Res 2002; 946:262-71. [PMID: 12137930 DOI: 10.1016/s0006-8993(02)02894-9] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Activation of kappa-opioid receptors (KOR) in the medial prefrontal cortex (mPFC) modulates excitatory transmission, which may involve interactions with N-methyl-D-aspartate (NMDA) glutamate receptors. We investigated possible anatomical correlates of this modulation by using dual labeling electron microscopy to examine the cellular distributions of antibodies raised against KOR and the R1 subunit of the NMDA receptor (NR1). KOR immunoreactivity primarily was localized to plasma and vesicular membranes of axons and axon terminals that were morphologically heterogeneous. A small proportion of KOR immunoreactivity was associated with cytosolic compartments of dendrites and membranes of glial processes. NR1 labeling was mainly postsynaptic, associated most often with membranes of cytoplasmic organelles in cell bodies and large dendrites and plasmalemmal surfaces of distal dendrites. The remaining NR1-labeled profiles were axonal profiles and glial processes. Of all cellular associations between labeled profiles, the majority were KOR-labeled axons that contacted NR1-immunoreactive dendrites or cell bodies. Occasionally the two antigens were colocalized in axon terminals that formed either asymmetric synapses or displayed varicose morphology. KOR and NR1 also were colocalized within dendrites, and rarely were observed in the same cell bodies. Occasionally glial processes coursing adjacent to axo-spinous appositions expressed both KOR and NR1 immunoreactivity. These results indicate that ligand activation of KOR or NMDA receptors differentially modulates excitatory transmission in the mPFC through pre- and postsynaptic mechanisms, respectively. The data also suggest more minor roles for colocalized KOR and NMDA receptors in shared regulation of presynaptic transmitter release, postsynaptic responsivity, and glial function.
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Affiliation(s)
- Adena L Svingos
- Department of Neurology and Neuroscience, Division of Neurobiology, Weill Medical College of Cornell University, 411 E. 69th St., New York, NY 10021, USA.
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25
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Abstract
To investigate the properties of NMDA receptors expressed in new-born rat hippocampal granule cells, recordings were made of single-channel currents produced by application of glutamate or NMDA to outside-out membrane patches. Outside-out patches displayed two distinct patterns of single-channel activity. In some patches only high conductance single-channel activity composed of 42 and 50 pS currents was observed while in others both high (42 and 50 pS) and low (17 and 33 pS) conductance single-channel currents occurred. An absence of direct transitions connecting the smallest (17 pS) and largest (50 pS) conductance unitary currents, as well as an absence of direct transitions connecting 17, 42 and 50 pS currents in sequence, suggested that high and low conductance single-channel activity may have been produced as a result of the activation of two distinct NMDA receptor populations. The NR2B subunit-selective NMDA receptor antagonist, ifenprodil, blocked the high conductance currents suggesting that these receptors contain the NR2B subunit while a clear asymmetry in the frequency of direct transitions between 17 and 42 pS conductance levels indicates the presence of NMDA receptors containing NR2D subunits. In patches containing both high and low conductance-channel activity, evidence for negative coupling between NR2B- and NR2D-like channel activity was observed, suggesting receptors containing these subunits do not gate independently or that both NR2B and NR2D subunits may be part of a single receptor molecule. We conclude that NMDA receptors in P0 hippocampal granule cells are likely to be a mixture of NR1/NR2B diheteromers and receptors of novel molecular composition that may be triheteromeric receptors composed of NR1, NR2B and NR2D subunits.
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Affiliation(s)
- Juan C Piña-Crespo
- Department of Pharmacology, University College London, Gower Street, London WC1E 6BT, UK
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26
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Mishra OP, Fritz KI, Delivoria-Papadopoulos M. NMDA receptor and neonatal hypoxic brain injury. MENTAL RETARDATION AND DEVELOPMENTAL DISABILITIES RESEARCH REVIEWS 2002; 7:249-53. [PMID: 11754518 DOI: 10.1002/mrdd.1034] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The NMDA-type glutamate receptor is a predominant mediator of excitotoxicity in the immature brain due to overexpression of the receptor in the developing brain. Within the development period however, the extent of NMDA receptor mediated processes including hypoxia-induced excitotoxicity may depend on the ontogeny of the NMDA receptor recognition and modulation sites, and subunits leading to altered function of the ion-channel comples. The function of the receptor may be modified by intracellular mechanisms such as phosphorylation/dephosphorylation, nitration, and generation of free radicals including nitric oxide. The susceptibility of the developing brain to hypoxia depends on several factors: the lipid composition of the brain cell membrane; the rate of membrane lipid peroxidation and the status of anti-oxidant defenses; the development and modulation of the NMDA receptor sites; the intracellular Ca(2+) influx mechanisms; expression of apoptotic and antiapoptotic genes such as Bax and Bcl-2; and the activation of initiator caspases and caspase-3, the "executioner" of cell death. The developmental status of these cellular mechanisms and their response to hypoxia determine the fate of the hypoxic cell in the developing brain in the fetus and the newborn.
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Affiliation(s)
- O P Mishra
- Department of Pediatrics, MCP Hahnemann University and St. Christopher's Hospital for Children, Philadelphia, Pennsylvania, USA.
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27
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Reader TA, Sénécal J. Topology of ionotropic glutamate receptors in brains of heterozygous and homozygous weaver mutant mice. Synapse 2001; 42:213-33. [PMID: 11746720 DOI: 10.1002/syn.10007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In weaver mice, mutation of a G-protein inwardly rectifying K(+) channel leads to a cerebellar developmental anomaly characterized by granule and Purkinje cell loss and, in addition, degeneration of dopaminergic neurons. To evaluate other deficits, ionotropic glutamate receptors sensitive to N-methyl-D-aspartate (NMDA), amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA), and kainic acid (KA) were examined by autoradiography with [(3)H]MK-801, [(3)H]AMPA, and [(3)H]KA. These surveys were carried out in selected areas of cerebral cortex, hippocampus and related limbic regions, basal ganglia, thalamus, hypothalamus, brainstem, and cerebellum from heterozygous (wv/+) and homozygous (wv/wv) weaver mutants, and compared to wild-type (+/+) mice. In wv/+ and wv/wv mutants, NMDA receptor levels were lower in cortical areas, septum, hippocampus, subiculum, neostriatum, nucleus accumbens, superior colliculus, and in the cerebellar granular layer. Densities of KA receptors were lower in cortical areas, hippocampus, limbic system structures, neostriatum, nucleus accumbens, thalamus and hypothalamus, superior and inferior colliculi, and cerebellar cortex of wv/wv mutants. Levels of AMPA receptors in the weaver were higher than in +/+ mice, particularly in somatosensory and piriform cortices and periaqueductal gray of wv/+, and in somatosensory cortex, CA1 field of Ammon's horn and cerebellar granular layer of wv/wv. Abnormal developmental signals, aberrant cellular responses, or a distorted balance between neurotransmitter interactions may underlie such widespread and reciprocal glutamate receptor alterations, while in the case of cerebellar cortex, NMDA receptors are lacking due to a massive disappearance of cerebellar granule cells and some loss of Purkinje neurons.
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Affiliation(s)
- T A Reader
- Centre de recherche en sciences neurologiques, Département de physiologie, Faculté de médecine, Université de Montréal, Montréal, Quebec, H3C 3J7 Canada.
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28
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Abdel-Naby Sayed M, Noda Y, Mahmoud Hamdy M, Mamiya T, Nagai T, Furukawa H, Nabeshima T. Enhancement of immobility induced by repeated phencyclidine injection: association with c-Fos protein in the mouse brain. Behav Brain Res 2001; 124:71-6. [PMID: 11423167 DOI: 10.1016/s0166-4328(01)00235-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Immunohistochemistry of c-Fos protein was performed to study changes in neuronal activity in discrete brain areas of mice repeatedly treated with phencyclidine (PCP) showing enhancement of immobility in the forced swimming test, this behavioral change being considered as avolition, which is one of negative symptoms of schizophrenia. Repeated treatment with PCP significantly prolonged immobility time in the forced swimming test, compared with saline treatment. The c-Fos protein expression of mice showing PCP-induced enhancement of immobility was increased in certain brain regions, such as the retrosplenial cortex, pyriform cortices, pontine nuclei, cingulate, frontal cortex and thalamus, compared with that of PCP-treated, non-swimming and saline-treated, swimming groups. These results suggest that increased c-Fos protein is involved in the expression of PCP-induced enhancement of immobility, and c-Fos expression plays a role in negative symptoms-like behavioral changes.
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Affiliation(s)
- M Abdel-Naby Sayed
- Department of Neuropsychopharmacology and Hospital Pharmacy, Nagoya University Graduate School of Medicine, 65 Tsuruma-cho, Showa-ku, Nagoya 466-8560, Japan
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29
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Reader TA, Sénécal J. Distribution of glutamate receptors of the NMDA subtype in brains of heterozygous and homozygous weaver mutant mice. Neurochem Res 2001; 26:579-89. [PMID: 11519718 DOI: 10.1023/a:1010922900470] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In weaver mice, mutation of an G-protein inwardly rectifying K+ channel leads to a cerebellar developmental anomaly characterized by granule and Purkinje cell loss and, in addition, degeneration of dopaminergic neurons. To evaluate other deficits, glutamate receptors sensitive to N-methyl-D-aspartate (NMDA) were examined by autoradiography with [3H]MK-801 in 36 brain regions from heterozygous (wv/+) and homozygous (wv/wv) weaver mutants, and compared to wild type (+/+) mice. In wv/+ and wv/wv mutants labelling decreased in cortical regions, septum, hippocampus, subiculum, neostriatum, nucleus accumbens, superior colliculus and in the cerebellar granular layer. The reductions in [3H]MK-801 binding were particularly specific in the cerebellar granular layer of wv/wv mutants, but an ubiquitous altered NMDA receptor topology was revealed in other brain regions. Abnormal developmental signals, or aberrant cellular responses, may underlie widespread NMDA receptor reductions, while in cerebellar cortex they could be lacking due to the massive loss of cerebellar granule cells.
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Affiliation(s)
- T A Reader
- Centre de Recherche en Sciences Neurologiques, Département de physiologie, Faculté de Médecine, Université de Montreal, Quebec, Canada.
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30
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Mugnaini M, Meoni P, Bunnemann B, Corsi M, Bowery NG. Allosteric modulation of [3H]-CGP39653 binding through the glycine site of the NMDA receptor: further studies in rat and human brain. Br J Pharmacol 2001; 132:1883-97. [PMID: 11309261 PMCID: PMC1572734 DOI: 10.1038/sj.bjp.0704017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2000] [Revised: 02/01/2001] [Accepted: 02/01/2001] [Indexed: 11/08/2022] Open
Abstract
Binding of D,L-(E)-2-amino-4-[(3)H]-propyl-5-phosphono-3-pentenoic acid ([(3)H]-CGP39653), a selective antagonist at the glutamate site of the NMDA receptor, is modulated by glycine in rat brain tissue. We have further investigated this phenomenon in rodent and human brain by means of receptor binding and quantitative autoradiography techniques. In rat cerebral cortical membranes the glycine antagonist 3-[2-(Phenylaminocarbonyl)ethenyl]-4,6-dichloro-indole-2-carboxylic acid sodium salt (GV150526A) did not change basal [(3)H]-CGP39653 binding, but competitively reversed the high affinity component of [(3)H]-CGP39653 binding inhibition by glycine, with a pK(B) value of 8.38, in line with its affinity for the glycine site (pK(i)=8.49 vs. [(3)H]-glycine). Glycine (10 microM) significantly decreased [(3)H]-CGP39653 affinity for the NMDA receptor (with no change in the B(max)), whereas enhanced L-glutamate affinity (P<0.05, paired-samples Student's t-test). In rat brain sections the addition of GV150526A (30 microM) to the incubation medium increased [(3)H]-CGP39653 binding to 208% of control (average between areas), indicating the presence of endogenous glycine. The enhancement presented significant regional differences (P<0.05, two-way ANOVA), with striatum higher than cerebral cortex (282 and 187% of control, respectively; P<0.05, Fisher's LSD). On the contrary, there was not any significant variation in affinity values of [(3)H]-CGP39653, L-glutamate, glycine and GV150526A in striatal and cortical membranes. These results confirmed the existence of regionally distinct NMDA receptors subtypes with different glycine/glutamate allosteric modulation. Whole brain autoradiography revealed an uneven distribution of [(3)H]-CGP39653 binding sites in human brain. High levels of binding were determined in hippocampus and in cingulate, frontoparietal and insular cortex. Intermediate to low levels of binding were found in diencephalic nuclei and basal ganglia. [(3)H]-CGP39653 binding was increased to 216% of control (mean between areas) by 30 microM GV150526A. The enhancement, however, did not present significant regional differences. These results introduce GV150526A as a useful tool to identify NMDA receptor subtypes by means of receptor autoradiography; moreover, they demonstrate that the allosteric inhibition of [(3)H]-CGP39653 binding by glycine parallels an increase in receptor affinity to the endogenous ligand L-glutamate. Finally, this study provides the first detailed anatomical description of the regional distribution of [(3)H]-CGP39653 binding sites in human brain.
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Affiliation(s)
- M Mugnaini
- GlaxoSmithKline Group, GlaxoWellcome S. p. A., Medicines Research Centre, Via Fleming 4, 37100 Verona, Italy.
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Matsuzaki H, Tamatani M, Yamaguchi A, Namikawa K, Kiyama H, Vitek MP, Mitsuda N, Tohyama M. Vascular endothelial growth factor rescues hippocampal neurons from glutamate‐induced toxicity: signal transduction cascades. FASEB J 2001. [DOI: 10.1096/fj.00-0495fje] [Citation(s) in RCA: 212] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Hideo Matsuzaki
- Department of Anatomy and Neuroscience, Graduate School of Medicine Osaka University 2-2 Yamadaoka Suita Osaka 565-0871 Japan
- CREST JST (Japan Science and Technology) 4-1-8 Hon-machi Kawaguchi Saitama 332-0012 Japan
| | - Michio Tamatani
- Department of Anatomy and Neuroscience, Graduate School of Medicine Osaka University 2-2 Yamadaoka Suita Osaka 565-0871 Japan
- CREST JST (Japan Science and Technology) 4-1-8 Hon-machi Kawaguchi Saitama 332-0012 Japan
| | - Atsushi Yamaguchi
- Department of Anatomy and Neuroscience, Graduate School of Medicine Osaka University 2-2 Yamadaoka Suita Osaka 565-0871 Japan
- CREST JST (Japan Science and Technology) 4-1-8 Hon-machi Kawaguchi Saitama 332-0012 Japan
| | - Kazuhiko Namikawa
- Department of Anatomy Asahikawa Medical College 4-5-3-11, Nishikagura Asahikawa Hokkaido 078-8510 Japan
| | - Hiroshi Kiyama
- Department of Anatomy Asahikawa Medical College 4-5-3-11, Nishikagura Asahikawa Hokkaido 078-8510 Japan
- CREST JST (Japan Science and Technology) 4-1-8 Hon-machi Kawaguchi Saitama 332-0012 Japan
| | - Michael P. Vitek
- Department of Neurology Duke University Medical Center Durham NC 27710
| | - Noriaki Mitsuda
- Department of Anatomy and Neuroscience, Graduate School of Medicine Osaka University 2-2 Yamadaoka Suita Osaka 565-0871 Japan
- CREST JST (Japan Science and Technology) 4-1-8 Hon-machi Kawaguchi Saitama 332-0012 Japan
| | - Masaya Tohyama
- Department of Anatomy and Neuroscience, Graduate School of Medicine Osaka University 2-2 Yamadaoka Suita Osaka 565-0871 Japan
- CREST JST (Japan Science and Technology) 4-1-8 Hon-machi Kawaguchi Saitama 332-0012 Japan
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32
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Albensi BC, Alasti N, Mueller AL. Long-term potentiation in the presence of NMDA receptor antagonist arylalkylamine spider toxins. J Neurosci Res 2000; 62:177-85. [PMID: 11020211 DOI: 10.1002/1097-4547(20001015)62:2<177::aid-jnr3>3.0.co;2-d] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The role of the NMDA receptor (NMDAR) in long-term potentiation (LTP) is now well established. All potent NMDAR antagonists known to date inhibit the induction of LTP at the Schaffer collateral-CA1 pyramidal cell synapse in rat hippocampus, regardless of their site and mechanism of action. Arylalkylamine toxins are noncompetitive NMDAR antagonists in the mammalian central nervous system (CNS). The synthetic toxins argiotoxin-636 (Arg-636), Joro spider toxin (JSTX-3), alpha-agatoxin-489 and -505 (Agel-489 and Agel-505) and philanthotoxin-433 (delta-PhTX) were found in the present study to have no effect on the induction of LTP in the Schaffer collateral-CA1 pyramidal cell pathway in rat hippocampal slices maintained in vitro. Arylalkylamine toxins represent a class of potent NMDAR antagonists that fail to affect hippocampal LTP, and thus provide novel structural leads for the development of NMDAR antagonists that do not impair cognition.
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Affiliation(s)
- B C Albensi
- NPS Pharmaceuticals, Inc., Salt Lake City, Utah 84108, USA
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33
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Strazielle C, Lalonde R, Reader TA. Autoradiography of glutamate receptor binding in adult Lurcher mutant mice. J Neuropathol Exp Neurol 2000; 59:707-22. [PMID: 10952061 DOI: 10.1093/jnen/59.8.707] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The mutation Lurcher, resulting from a gain of malfunction of the delta2 glutamate receptor expressed specifically by cerebellar Purkinje cells, causes a primary total loss of these neurons of the cerebellar cortex, as well as the secondary degeneration of cerebellar granule and inferior olive neurons. The distributions of glutamate receptors sensitive to amino-methylisoxazole-propionic acid (AMPA), to kainic acid (KA), and to N-methyl-D-aspartic acid (NMDA) as well as metabotropic sites (MET1 and MET2) were examined in wild type and Lurcher mice by quantitative autoradiography. This study was undertaken to determine the gene effect on the distribution of the various glutamate receptor subtypes, as well as how the cerebellar lesion affects the glutamatergic system in other brain regions. In cerebellum, there were postsynaptic AMPA and metabotropic receptors on Purkinje cells, postsynaptic NMDA receptors on granule cells, as well as KA receptors on granule cells or on parallel fibers. Taking into account surface areas, binding to all receptor subtypes was lower in the cerebellar cortex of Lurcher mutants than in wild type mice, while in the deep cerebellar nuclei only KA receptors were diminished. In other brain regions, the alterations followed always the same pattern characterized by a decrease of NMDA and KA receptors but with an increase of AMPA sites; these reciprocal changes were seen in thalamus. neostriatum, limbic regions, and motor cerebral cortical regions. Comparisons of glutamate receptor distribution in Lurcher mutants and in human autosomal cerebellar ataxia may permit further understanding of the role of glutamate-induced toxicity on neuronal death in these heredo-degenerative diseases.
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Affiliation(s)
- C Strazielle
- Centre de Recherche en Sciences Neurologiques, Faculté de Médecine, Université de Montréal, Qc, Canada
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34
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Jang CG, Rockhold RW, Ho IK. An autoradiographic study of [3H]AMPA receptor binding and in situ hybridization of AMPA sensitive glutamate receptor A (GluR-A) subunits following morphine withdrawal in the rat brain. Brain Res Bull 2000; 52:217-21. [PMID: 10822164 DOI: 10.1016/s0361-9230(00)00261-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Chronic treatment with opioids is well known to result in the development of physical dependence. More recently, glutamatergic mechanisms have been implicated in expression of the withdrawal syndrome from opioids. To better examine glutamatergic involvement, an autoradiographic study of [3H]AMPA receptor binding and an assessment of in situ hybridization of AMPA sensitive glutamate receptor A (GluR-A) subunits in the rat brain were each performed 7 h after withdrawal from morphine infusion. Animals were rendered dependent by intracerebroventricular (i.c.v.) infusion of morphine (26 nmol/microl/h) via osmotic minipumps for 3 days. Brain sections of 14-microm thickness were incubated with 15 nM [3H]AMPA for quantitation of binding to the AMPA receptor. The probe for in situ hybridization was labeled at its 3' end using terminal deoxynucleotidyl transferase and [35S]dATP. The highest degree of [3H]AMPA binding was shown in the hippocampus. The extent of [3H]AMPA binding was increased significantly in the cortex areas (18-21%), caudate-putamen (20%), and hippocampus (7-9%) of rats following withdrawal from morphine. The highest levels of mRNA for GluR-A, flop and flip subunits, were found in the dentate gyrus and in the CA3 region of the hippocampus, respectively. The levels of mRNA for the flop form of GluR-A were decreased in the CA3 of hippocampus (8%) of the rat brain. The levels of mRNA for the flip form of GluR-A were increased in the parietal cortex (7%) and the entorhinal cortex (8%). Increases in the binding of [3H]AMPA to its receptor may play an important role during withdrawal from morphine dependence.
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Affiliation(s)
- C G Jang
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, MS 39216-4505, USA
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35
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Pal R, Eaton MJ, Islam S, Hake-Frendscho M, Kumar KN, Michaelis EK. Immunocytochemical and in situ hybridization studies of the expression and distribution of three subunits of a complex with N-methyl-D-aspartate receptor-like properties. Neuroscience 2000; 94:1291-311. [PMID: 10625068 DOI: 10.1016/s0306-4522(99)00386-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
A group of four proteins with recognition sites for L-glutamate, N-methyl-D-aspartate, glycine, and competitive and non-competitive inhibitors of N-methyl-D-aspartate receptors was previously purified from rat brain synaptic membranes. The biochemical and immunochemical characteristics of this complex, as well as the sequences of the complementary DNAs of three subunits, are distinct from those of other glutamate receptors, transporters, or enzymes. The function of this complex has not yet been defined, but it appears to be involved in glutamate-induced neuronal excitation and toxicity. It is not known whether all protein components of the complex are expressed in the same populations of brain cells. In the present study, immunohistochemical and in situ hybridization were used to map the distribution of the glutamate-binding, glycine/thienylcyclohexylpiperidine-binding, and carboxypiperazinyl-propylphosphonate-binding protein subunits of the complex. These proteins were abundantly expressed in pyramidal neurons of the hippocampus and cerebral cortex, and in granule cells of the dentate gyrus, cerebellum, and olfactory tubercle. Based on these results, it was concluded that the three subunits of the complex have similar patterns of expression in rat brain. The distribution of one subunit of the complex, glutamate-binding protein, was traced throughout the rat brain, thus providing a potential map of the expression of the complex in rodent brain. In addition, probes were developed in the present study that should be useful in future explorations of the role of these proteins in brain function and of the possible co-localization of the protein subunits in single cells or cell processes.
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Affiliation(s)
- R Pal
- The Department of Pharmacology and Toxicology and the Center for Neurobiology and Immunology Research, University of Kansas, Lawrence, USA
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36
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Leung LS, Shen B. N-methyl-D-aspartate receptor antagonists are less effective in blocking long-term potentiation at apical than basal dendrites in hippocampal CA1 of awake rats. Hippocampus 2000; 9:617-30. [PMID: 10641754 DOI: 10.1002/(sici)1098-1063(1999)9:6<617::aid-hipo2>3.0.co;2-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Long-term potentiation (LTP) of field excitatory postsynaptic potentials (fEPSPs) at the apical or basal dendrites of CA1 pyramidal cells was induced by stimulation with a 1-s train of 200-Hz pulses in awake rats, with or without the presence of various doses of an N-methyl-D-aspartate (NMDA) receptor antagonist. Apical LTP was blocked by an intracerebroventricular (i.c.v.) dose of 40 microg D-2-amino-5-phosphonopentanoic acid (D-AP5) or 20 mg/kg i.p. D-2-amino-4-methyl-5-phosphono-3-pentanoic acid (CGP-40116), whereas basal LTP was blocked by half the dose of D-AP5 or CGP-40116. The noncompetitive antagonist MK-801 (< or =1 mg/kg i.p.) had no significant effect on apical LTP. Apical LTP was not blocked by i.c.v. nifedipine. The effect of an NMDA receptor antagonist alone on apical and basal fEPSPs was also evaluated, to assess the net effect of the NMDA receptor antagonist in blocking LTP. MK-801 (0.5-1 mg/kg i.p.) or CGP-40116 (10-20 mg/kg i.p.) but not D-AP5 suppressed apical fEPSPs for several hours and confounded the expression of apical LTP during this time. We concluded that hippocampal LTP at different synapses has different sensitivity to NMDA receptor antagonists and that a general blockade of hippocampal NMDA receptor functions cannot be inferred by a single hippocampal LTP measure.
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Affiliation(s)
- L S Leung
- Department of Physiology and Clinical Neurological Sciences, University of Western Ontario, London, Canada.
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37
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Jang C, Park Y, Rockhold RW, Ho IK. Autoradiographic study of NMDA-displaceable [3H]glutamate and [3H]MK-801 binding during butorphanol withdrawal in the rat brain. Brain Res 1999; 845:236-41. [PMID: 10536204 DOI: 10.1016/s0006-8993(99)01949-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Influences of continuous administration of butorphanol on the autoradiography of [3H]glutamate binding and [3H]MK-801 binding were investigated to study the effects of butorphanol withdrawal on NMDA receptors. Rats were administered butorphanol (26 nmol microl(-1) h(-1)) by continuous intracerebroventricular (i.c.v.) infusion through pre-implanted cannula connected to osmotic mini-pumps for 3 days. Rats were then sacrificed at 2, 7, and 24 h after discontinuation of butorphanol infusion. [3H]MK-801 binding was slightly increased in the cortical area, hippocampus, and cerebellum in 2, 7, and 24 h withdrawal groups and was shown most significant increase in the 7 h withdrawal group. NMDA-displaceable [3H]glutamate binding was markedly increased in the cortical area, striatum, septum, hippocampus, thalamus, and cerebellum in 7 h withdrawal group and was significantly increased in the striatum, hippocampus, and thalamus in 24 h withdrawal group. These results demonstrate that the development of butorphanol withdrawal is more prominent by 7 h after discontinuation of butorphanol infusion and suggest that NMDA binding sites at NMDA receptors may play more important role in the development of butorphanol withdrawal than that of channel blocking sites.
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Affiliation(s)
- C Jang
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216-4505, USA
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38
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Chen Q, Surmeier DJ, Reiner A. NMDA and non-NMDA receptor-mediated excitotoxicity are potentiated in cultured striatal neurons by prior chronic depolarization. Exp Neurol 1999; 159:283-96. [PMID: 10486197 DOI: 10.1006/exnr.1999.7135] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The excitatory input from cortex and/or thalamus to striatum appears to promote the maturation of glutamate receptors on striatal neurons, but the mechanisms by which it does so have been uncertain. To explore the possibility that the excitatory input to striatum might influence glutamate receptor maturation on striatal neurons, at least in part, by its depolarizing effect on striatal neurons, we examined the influence of chronic KCl depolarization on the development of glutamate receptor-mediated excitotoxic vulnerability and glutamate receptors in cultured striatal neurons. Dissociated striatal neurons from E17 rat embryos were cultured for 2 weeks in Barrett's medium containing either low (3 mM) or high (25 mM) KCl. The vulnerability of these neurons to NMDA receptor agonists (NMDA and quinolinic acid), non-NMDA receptor agonists (AMPA and KA), and a metabotropic glutamate receptor agonist (trans-ACPD) was examined by monitoring cell loss 24 h after a 1-h agonist exposure. We found that high-KCl rearing potentiated the cell loss observed with 500 microM NMDA or 250 microM KA and yielded cell loss with 250 microM AMPA that was not evident under low KCl rearing. In contrast, neither QA up to 5 mM nor trans-ACPD had a significant toxic effect in either KCl group. ELISA revealed that chronic high KCl doubled the abundance of NMDA NR2A/B, AMPA GluR2/3, and KA GluR5-7 receptor subunits on cultured striatal neurons and more than doubled AMPA GluR1 and GluR4 subunits, but had no effect on NMDA NR1 subunit levels. These receptor changes may contribute to the potentiation of NMDA and non-NMDA receptor-mediated excitotoxicity shown by these neurons following chronic high-KCl rearing. Our studies suggest that membrane depolarization produced by corticostriatal and/or thalamostriatal innervation may be required for maturation of glutamate receptors on striatal neurons, and such maturation may be important for expression of NMDA and non-NMDA receptor-mediated excitotoxicity by striatal neurons. Striatal cultures raised under chronically depolarized conditions may, thus, provide a more appropriate culture model to study the role of NMDA or non-NMDA receptor subtypes in excitotoxicity in striatum.
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MESH Headings
- Animals
- Anti-Anxiety Agents/pharmacology
- Benzodiazepines
- Calcium/metabolism
- Cells, Cultured
- Corpus Striatum/cytology
- Cycloleucine/analogs & derivatives
- Cycloleucine/pharmacology
- Dose-Response Relationship, Drug
- Excitatory Amino Acid Agonists/pharmacology
- Female
- Fetus/cytology
- Kainic Acid/pharmacology
- Membrane Potentials/drug effects
- Membrane Potentials/physiology
- N-Methylaspartate/pharmacology
- Nerve Degeneration/physiopathology
- Neurons/chemistry
- Neurons/cytology
- Neurons/physiology
- Neuroprotective Agents/pharmacology
- Neurotoxins/pharmacology
- Potassium Chloride/pharmacology
- Pregnancy
- Quinolinic Acid/pharmacology
- Rats
- Rats, Sprague-Dawley
- Receptors, AMPA/analysis
- Receptors, AMPA/physiology
- Receptors, Kainic Acid/analysis
- Receptors, Kainic Acid/physiology
- Receptors, Metabotropic Glutamate/analysis
- Receptors, Metabotropic Glutamate/physiology
- Receptors, N-Methyl-D-Aspartate/analysis
- Receptors, N-Methyl-D-Aspartate/physiology
- alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid/pharmacology
- GluK2 Kainate Receptor
- GluK3 Kainate Receptor
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Affiliation(s)
- Q Chen
- Department of Anatomy and Neurobiology, University of Tennessee-Memphis, Memphis, Tennessee, 38163, USA
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Miyazaki J, Nakanishi S, Jingami H. Expression and characterization of a glycine-binding fragment of the N-methyl-D-aspartate receptor subunit NR1. Biochem J 1999; 340 ( Pt 3):687-92. [PMID: 10359652 PMCID: PMC1220299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
N-Methyl-D-aspartate receptor channels are composed of an NR1 subunit and at least one of the NR2 subunits (NR2A-D). Activation of the N-methyl-d-aspartate receptor requires the co-agonists glycine and glutamate. It has been proposed that the NR1 subunit possesses a glycine-binding site. We have expressed a soluble form of the NR1 subunit, which was produced by connecting the N-terminal extracellular region with the extracellular loop between the third and fourth membrane segments, by a baculovirus system along with full-length and truncated membrane-bound forms. The soluble NR1 receptor was efficiently secreted into the culture medium and showed a high affinity for ligands. The Kd of a glycine-site antagonist, [3H]MDL 105,519 [(E)-3-(2-phenyl-2-carboxyethenyl)-4, 6-dichloro-1H-indole-2-carboxylic acid], for the soluble receptor was 3.89+/-0.97 nM, which was comparable to the Kd of 4.47+/-1.39 nM for the membrane-bound full-length form. These values were close to the values reported previously with the use of rat brain membranes and Chinese hamster ovary cells expressing the full-length form of the NR1 subunit. The Ki values of other glycine-site antagonists, L-689,560 (trans-2-carboxy-5,7-dichloro - 4 - phenylaminocarbonylamino - 1,2,3,4 - tetrahydroquinoline), 5, 7-dichlorokynurenate and 5,7-dinitroquinoxaline-2,3-dione, for the soluble receptor were also similar to those for the full-length form of NR1. [3H]MDL 105,519 binding was also inhibited by the agonists glycine and d-serine. Thus the affinity and selectivity of ligand-binding characteristics of the NR1 subunit is conferred on the soluble form of the NR1 subunit. This soluble receptor provides a good experimental tool for initiating a biophysical analysis of the N-methyl-d-aspartate receptor channel protein.
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Affiliation(s)
- J Miyazaki
- Department of Molecular Biology, Biomolecular Engineering Research Institute (BERI), 6-2-3 Furuedai, Suita, Osaka 565-0874, Japan
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40
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Monaghan DT, Andaloro VJ, Skifter DA. Molecular determinants of NMDA receptor pharmacological diversity. PROGRESS IN BRAIN RESEARCH 1999; 116:171-90. [PMID: 9932377 DOI: 10.1016/s0079-6123(08)60437-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Affiliation(s)
- D T Monaghan
- Department of Pharmacology, University of Nebraska Medical Center, Omaha 68198-6260, USA.
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41
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Hauben U, D'Hooge R, Soetens E, De Deyn PP. Effects of oral administration of the competitive N-methyl-D-aspartate antagonist, CGP 40116, on passive avoidance, spatial learning, and neuromotor abilities in mice. Brain Res Bull 1999; 48:333-41. [PMID: 10229343 DOI: 10.1016/s0361-9230(99)00008-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The effects were investigated of the potent competitive N-methyl-D-aspartate (NMDA) receptor antagonist CGP 40116[D-(E)-2-amino-4-methyl-5-phosphono-3-pentenoic acid] on the performance of mice in water maze and passive avoidance tasks, and in wire suspension, rotarod, and cage activity tests. The drug was administered per os (p.o.) in its anticonvulsant dose range. CGP 40116 dose-dependently impaired passive avoidance learning when given before, but not when given after training. The antagonist (5, 10, and 20 mg/kg, administered 4 h before each training session) dose-dependently affected water maze acquisition, and impaired retention test performance in both hidden- and visible-platform water maze tasks. In addition, the drug dose-dependently decreased swimming speed during water maze acquisition. Repeated administration of CGP 40116 (20 mg/kg, p.o.) persistently decreased cage activity and wire suspension test performance, whereas motor coordination and equilibrium on the rotarod apparatus remained unimpaired. In our administration protocol, no tolerance was found to the effects of the drug on passive avoidance learning and neuromotor abilities. The parallel effects of CGP 40116 on memory and motor performance are discussed, and it was concluded that the antagonist impairs neuromotor abilities and also induces memory impairments which cannot be entirely reduced to motor interference.
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Affiliation(s)
- U Hauben
- Born-Bunge Foundation, and Department of Neurology-Memory Clinic, Middelheim General Hospital, University of Antwerp, Belgium
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42
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Glutamate Receptors and Excitotoxic Mechanisms in Alzheimer’s Disease. Cereb Cortex 1999. [DOI: 10.1007/978-1-4615-4885-0_18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022] Open
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43
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Jang CG, Oh S, Zhu H, Ho IK. Autoradiography of [3H]glutamate binding during pentobarbital tolerance and withdrawal in the rat. Brain Res Bull 1999; 48:99-102. [PMID: 10210174 DOI: 10.1016/s0361-9230(98)00152-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The influence of centrally administered pentobarbital on [3H]glutamate receptor binding in the rat brain was examined. Animals were rendered tolerant by intracerebroventricular (i.c.v.) infusion through osmotic minipumps with pentobarbital (300 microg/10 microl/h, for 6 days), and dependent, by 24 h after withdrawal from pentobarbital. Pentobarbital tolerant rats have significant increases in [3H]glutamate binding in the cortex and hippocampus area. Pentobarbital withdrawal produced increases in glutamate binding in many regions, e.g., the cortex, hippocampus area, thalamus, and cerebellum. These results show that chronic i.c.v. infusion with pentobarbital increases N-methyl-D-aspartate (NMDA) displaceable [3H]glutamate binding, suggesting that an increase in NMDA binding sites may play an important role in the development of tolerance to and withdrawal from pentobarbital.
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Affiliation(s)
- C G Jang
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson 39216-4505, USA
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44
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Limbird LE, Motulsky H. Receptor Identification and Characterization. Compr Physiol 1998. [DOI: 10.1002/cphy.cp070104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Jang CG, Oh S, Ho IK. Changes in NMDAR2 subunit mRNA levels during pentobarbital tolerance/withdrawal in the rat brain: an in situ hybridization study. Neurochem Res 1998; 23:1371-7. [PMID: 9814547 DOI: 10.1023/a:1020746505854] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Little is known about the functional modulation of NMDA receptor subunits at the molecular level. Therefore, a series of experiments were conducted to elucidate more fully the role of NMDA receptor subtypes in pentobarbital tolerance and withdrawal. We investigated the influence of centrally administered pentobarbital on the regulation of mRNA levels of the family of NMDA receptor 2 (NR2) subtypes (NR2A, NR2B, and NR2C) by in situ hybridization histochemistry in rat brain. Animals were rendered tolerant by continuous intracerebroventricular (i.c.v.) infusion with pentobarbital (300 microg/10 microl/hr for 6 days) through pre-implanted cannulae connected to osmotic mini-pumps, and dependent, by abrupt withdrawal from pentobarbital. The NR2A subunit mRNA was increased in cortical areas in pentobarbital tolerant and withdrawal rats. In contrast, the NR2B mRNA was decreased in parietal cortex and hippocampus in both tolerance and withdrawal rats. The level of NR2C mRNA was increased in withdrawal rats, while there was no change in tolerant rats. These results indicate that continuous i.c.v. infusion with pentobarbital alters NR2 subunit mRNA expression in the rat brain, suggesting that NR2 subunits may play an important role in the development of tolerance to and withdrawal from pentobarbital.
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Affiliation(s)
- C G Jang
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson 39216-4505, USA
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Cull-Candy SG, Brickley SG, Misra C, Feldmeyer D, Momiyama A, Farrant M. NMDA receptor diversity in the cerebellum: identification of subunits contributing to functional receptors. Neuropharmacology 1998; 37:1369-80. [PMID: 9849672 DOI: 10.1016/s0028-3908(98)00119-1] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Recent studies of N-methyl-D-aspartate (NMDA) receptors have led to the suggestion that there are two distinct classes of native NMDA receptors, identifiable from their single-channel conductance properties. 'High-conductance' openings arise from NR2A- or NR2B-containing receptors, and 'low-conductance' openings arise from NR2C- or NR2D-containing receptors. In addition, the low-conductance channels show reduced sensitivity to block by Mg2+. The readily identified cell types and simple architecture of the cerebellum make it an ideal model system in which to determine the contribution of specific subunits to functional NMDA receptors. Furthermore, mRNA for all of these four NR2 subunits are represented in this brain region. We have examined NMDA channels in Purkinje cells, deep cerebellar nuclei (DCN) neurons and Golgi cells. First we find that NR2D-containing NMDA receptors give rise to low-conductance openings in cell-attached recordings from Purkinje cells. The characteristic conductance of these events cannot, therefore, be ascribed to patch excision. Second, patches from some DCN neurons exhibit mixed populations of high- and low-conductance openings. Third, Golgi cells also exhibit a mixed population of high- and low-conductance NMDA receptor openings. The features of these low-conductance openings are consistent with the presence of NR2D-containing NMDA receptors, as suggested by in situ hybridization data. On the other hand the existence of high-conductance channels, with properties typical of NR2B-containing receptors, was not expected. Our results provide new evidence about the subunit composition of NMDA receptors in identified cerebellar cells, and suggest that examination of single-channel properties is a potentially powerful approach for determining the possible subunit composition of native NMDA receptors.
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Affiliation(s)
- S G Cull-Candy
- Department of Pharmacology, University College London, UK.
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Giraldez L, Girardi E. Modification of [3H]MK801 binding to rat brain NMDA receptors after the administration of a convulsant drug and an adenosine analogue: a quantitative autoradiographic study. Neurochem Res 1998; 23:1327-36. [PMID: 9804290 DOI: 10.1023/a:1020708603495] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Specific [3H]MK801 binding to rat brain NMDA receptors after the administration of the convulsant drug 3-mercaptopropionic acid (MP) and the adenosine analogue cyclopentyladenosine (CPA) was studied by means of a quantitative autoradiographic method. MP administration (150 mg/kg, i.p.) caused significant decreases in [3H]MK801 binding in several hippocampus subareas and layers, mainly in CA1 and CA3 at seizure (11-27%) and postseizure (8-16%) and in cerebral occipital cortex at seizure (18-22%). In nucleus accumbens, a rise was observed at postseizure (44%) and a tendency to increase at seizure (24%). CPA (2mg/kg, i.p.) decreased ligand binding in hippocampus (CAI, CA2, CA3) (17-22%) and in occipital cerebral cortex (18-24%). When CPA was administered 30 minutes before MP (which delayed seizure onset) and rats were sacrificed at seizure, decreases in [3H]MK801 binding in several layers of CA1 and CA3 of hippocampus (11-27%) and in CA1, CA2, CA3 (24-35%) after CPA+MP postseizure, and an increase in CA2 after CPA and CPA+MP postseizure (20-34%), were observed. A drop was found in the occipital subarea (18-24%) after CPA and in the frontal and occipital subarea after CPA+MP postseizure (24-34%) while no changes were observed in any treatment involving the other cerebral cortex regions, thalamic nuclei, caudate putamen and olfactory tubercle. These results show that [3H]MK801 binding changes according to drug treatment and the area being studied, thus indicating a different role in seizure activity.
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Affiliation(s)
- L Giraldez
- Instituto de Biología Celular y de Neurociencia Prof Eduardo De Robertis, Facultad de Medicina, Universidad de Buenos Aires, Argentina
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Paudice P, Gemignani A, Raiteri M. Evidence for functional native NMDA receptors activated by glycine or D-serine alone in the absence of glutamatergic coagonist. Eur J Neurosci 1998; 10:2934-44. [PMID: 9758163 DOI: 10.1046/j.1460-9568.1998.00302.x] [Citation(s) in RCA: 37] [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
In this study we have examined the effects of N-methyl-D-aspartate (NMDA) receptor activation on the release of cholecystokinin and somatostatin from rat neocortical nerve endings. The release of cholecystokinin-like immunoreactivity (CCK-LI) and of somatostatin-like immunoreactivity (SRIF-LI) elicited by 12 mM K+ from superfused synaptosomes, but not the spontaneous release, was increased by NMDA in a concentration-dependent manner. The effects of NMDA could be prevented by antagonists selective for the glutamate recognition site, the receptor channel and the glycine site of the NMDA receptor. In the absence of NMDA, glycine increased on its own and in a concentration-dependent manner the depolarization-evoked release of both CCK-LI and SRIF-LI. This effect of glycine was strychnine-insensitive and could be mimicked by D-serine, a stereoselective agonist at the NMDA receptor glycine site. Antagonists selective for the glycine site or for the NMDA receptor channel prevented the effects of glycine/D-serine; these effects were, however, insensitive to blockade of the glutamate recognition site of the NMDA receptor, suggesting that glutamate released from synaptosomes or present as contaminant was not involved. The neuropeptide release elicited by D-serine was strongly inhibited by ifenprodil (0.3 microM) and by Zn2+ ions (50 nM), selective ligands at the NR2B and NR2A subunits of NMDA receptors, respectively. It is concluded that nerve terminals of CCK- and SRIF-releasing neurons possess non-conventional NMDA receptors whose channels can be operated by glycine or D-serine without apparent activation of the glutamatergic coagonist site. These receptors may display the triple subunit combination NR1/NR2A/NR2B.
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Affiliation(s)
- P Paudice
- Department of Experimental Medicine, University of Genova, Italy
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Boje KM, Lakhman SS. Chronic dosing with 1-aminocyclopropanecarboxylic acid, a glycine partial agonist, modulates NMDA inhibition of muscarinic-coupled PI hydrolysis in rat cortical slices. Neurochem Res 1998; 23:1167-74. [PMID: 9712186 DOI: 10.1023/a:1020773917240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Chronic dosing with the glycine partial NMDA agonist, 1-aminocyclopropanecarboxylic acid (ACPC) elicited an altered allosteric regulation of cortical NMDA receptor binding. The present study hypothesized that these allosteric receptor binding changes would be manifest as pharmacologically functional reductions in NMDA receptor activity following chronic ACPC dosing. NMDA inhibition of carbachol-induced phosphoinositide (PI) hydrolysis was used as a functional assay to assess NMDA receptor function in rat cerebral cortex. NMDA inhibition of stimulated PI turnover was similar in naive (46% +/- 4.5%; mean +/- SE; n = 34) and ACPC dosed rats (39% +/- 2.3%; n = 34). While ACPC reversed NMDA's inhibitory effects in naive rats (80% +/- 13%; n = 9), it was ineffective (P < 0.05) in ACPC pretreated rats (48% +/- 9.8%; n = 9). In contrast, the NMDA antagonists, MK-801 (ion channel), 7-chlorokynurenic acid (glycine site) and AP-7 (glutamate site), effectively reversed NMDA's inhibitory effects in naive and ACPC treated rats. The potency of these antagonists were unaltered by prior ACPC dosing. Thus, chronic ACPC therapy does not alter the functioning of the NMDA ion channel or glutamate receptor sites, but elicits functional tolerance to ACPC's actions in the cortical NMDA complex.
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Affiliation(s)
- K M Boje
- Department of Pharmaceutics, School of Pharmacy, University of Buffalo, New York 14260-1200, USA.
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Michaelis EK. Molecular biology of glutamate receptors in the central nervous system and their role in excitotoxicity, oxidative stress and aging. Prog Neurobiol 1998; 54:369-415. [PMID: 9522394 DOI: 10.1016/s0301-0082(97)00055-5] [Citation(s) in RCA: 389] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Forty years of research into the function of L-glutamic acid as a neurotransmitter in the vertebrate central nervous system (CNS) have uncovered a tremendous complexity in the actions of this excitatory neurotransmitter and an equally great complexity in the molecular structures of the receptors activated by L-glutamate. L-Glutamate is the most widespread excitatory transmitter system in the vertebrate CNS and in addition to its actions as a synaptic transmitter it produces long-lasting changes in neuronal excitability, synaptic structure and function, neuronal migration during development, and neuronal viability. These effects are produced through the activation of two general classes of receptors, those that form ion channels or "ionotropic" and those that are linked to G-proteins or "metabotropic". The pharmacological and physiological characterization of these various forms over the past two decades has led to the definition of three forms of ionotropic receptors, the kainate (KA), AMPA, and NMDA receptors, and three groups of metabotropic receptors. Twenty-seven genes are now identified for specific subunits of these receptors and another five proteins are likely to function as receptor subunits or receptor associated proteins. The regulation of expression of these protein subunits, their localization in neuronal and glial membranes, and their role in determining the physiological properties of glutamate receptors is a fertile field of current investigations into the cell and molecular biology of these receptors. Both ionotropic and metabotropic receptors are linked to multiple intracellular messengers, such as Ca2+, cyclic AMP, reactive oxygen species, and initiate multiple signaling cascades that determine neuronal growth, differentiation and survival. These cascades of complex molecular events are presented in this review.
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Affiliation(s)
- E K Michaelis
- Department of Pharmacology and Toxicology, University of Kansas, Lawrence 66047, USA
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