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Callahan PM, Terry AV, Nelson FR, Volkmann RA, Vinod AB, Zainuddin M, Menniti FS. Modulating inhibitory response control through potentiation of GluN2D subunit-containing NMDA receptors. Neuropharmacology 2020; 173:107994. [PMID: 32057801 DOI: 10.1016/j.neuropharm.2020.107994] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2019] [Revised: 01/16/2020] [Accepted: 02/05/2020] [Indexed: 01/15/2023]
Abstract
NMDA receptors containing GluN2D subunits are expressed in the subthalamic nucleus and external globus pallidus, key nuclei of the indirect and hyperdirect pathways of the basal ganglia. This circuitry integrates cortical input with dopaminergic signaling to select advantageous behaviors among available choices. In the experiments described here, we characterized the effects of PTC-174, a novel positive allosteric modulator (PAM) of GluN2D subunit-containing NMDA receptors, on response control regulated by this circuitry. The indirect pathway suppresses less advantageous behavioral choices, a manifestation of which is suppression of locomotor activity in rats. Systemic administration of PTC-174 produced a dose-dependent reduction in activity in rats placed in a novel open field or administered the stimulants MK-801 or amphetamine. The hyperdirect pathway controls release of decisions from the basal ganglia to the cortex to optimize choice processing. Such response control was modeled in rats as premature responding in the 5-choice serial reaction time (5-CSRT) task. PTC-174 produced a dose-dependent reduction in premature responding in this task. These data suggest that potentiation of GluN2D receptor activity by PTC-174 facilitates the complex basal ganglia information processing that underlies response control. The behavioral effects occurred at estimated free PTC-174 brain concentrations predicted to induce 10-50% increases in GluN2D activity. The present findings suggest the potential of GluN2D PAMs to modulate basal ganglia function and to treat neurological disorders related to dysfunctional response control.
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Affiliation(s)
- Patrick M Callahan
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, GA, 30912, USA; Small Animal Behavior Core, Augusta University, Augusta, GA, 30912, USA
| | - Alvin V Terry
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, GA, 30912, USA; Small Animal Behavior Core, Augusta University, Augusta, GA, 30912, USA
| | | | | | - A B Vinod
- Jubilant Biosys Ltd, Yeshwantpur, Bangalore, 560022, Karnataka, India
| | - Mohd Zainuddin
- Jubilant Biosys Ltd, Yeshwantpur, Bangalore, 560022, Karnataka, India
| | - Frank S Menniti
- The George & Anne Ryan Institute for Neuroscience, University of Rhode Island, Kingston, RI, 02881, USA.
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Deletion of the Na/HCO 3 Transporter NBCn1 Protects Hippocampal Neurons from NMDA-induced Seizures and Neurotoxicity in Mice. Sci Rep 2019; 9:15981. [PMID: 31690738 PMCID: PMC6831677 DOI: 10.1038/s41598-019-52413-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 09/09/2019] [Indexed: 12/13/2022] Open
Abstract
The Na/HCO3 cotransporter NBCn1/SLC4A7 can affect glutamate neurotoxicity in primary cultures of rat hippocampal neurons. Here, we examined NMDA-induced neurotoxicity in NBCn1 knockout mice to determine whether a similar effect also occurs in the mouse brain. In primary cultures of hippocampal neurons from knockouts, NMDA had no neurotoxic effects, determined by lactate dehydrogenase release and nitric oxide synthase (NOS)-dependent cGMP production. Male knockouts and wildtypes (6–8 weeks old) were then injected with NMDA (75 mg/kg; ip) and hippocampal neuronal damages were assessed. Wildtypes developed severe tonic-clonic seizures, whereas knockouts had mild seizure activity (motionless). In knockouts, the NOS activity, caspase-3 expression/activity and the number of TUNEL-positive cells were significantly low. Immunochemical analysis revealed decreased expression levels of the NMDA receptor subunit GluN1 and the postsynaptic density protein PSD-95 in knockouts. Extracellular recording from hippocampal slices showed no Mg2+/NMDA-mediated epileptiform events in knockouts. In conclusion, these results show a decrease in NMDA neurotoxicity by NBCn1 deletion. Given that acid extrusion has been known to prevent pH decrease and protect neurons from acid-induced damage, our study presents novel evidence that acid extrusion by NBCn1 stimulates neurotoxicity.
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Sadat-Shirazi MS, Vousooghi N, Alizadeh B, Makki SM, Zarei SZ, Nazari S, Zarrindast MR. Expression of NMDA receptor subunits in human blood lymphocytes: A peripheral biomarker in online computer game addiction. J Behav Addict 2018; 7:260-268. [PMID: 29788757 PMCID: PMC6174581 DOI: 10.1556/2006.7.2018.35] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Background and aims Repeated performance of some behaviors such as playing computer games could result in addiction. The NMDA receptor is critically involved in the development of behavioral and drug addictions. It has been claimed that the expression level of neurotransmitter receptors in the brain may be reflected in peripheral blood lymphocytes (PBLs). Methods Here, using a real-time PCR method, we have investigated the mRNA expression of GluN2A, GluN2D, GluN3A, and GluN3B subunits of the NMDA receptor in PBLs of male online computer game addicts (n = 25) in comparison with normal subjects (n = 26). Results Expression levels of GluN2A, GluN2D, and GluN3B subunits were not statistically different between game addicts and the control group. However, the mRNA expression of the GluN3A subunit was downregulated in PBLs of game addicts. Discussion and conclusions Transcriptional levels of GluN2A and GluN2D subunits in online computer game addicts are similar to our previously reported data of opioid addiction and are not different from the control group. However, unlike our earlier finding of drug addiction, the mRNA expression levels of GluN3A and GluN3B subunits in PBLs of game addicts are reduced and unchanged, respectively, compared with control subjects. It seems that the downregulated state of the GluN3A subunit of NMDA receptor in online computer game addicts is a finding that deserves more studies in the future to see whether it can serve as a peripheral biomarker in addiction studies, where the researcher wants to rule out the confusing effects of abused drugs.
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Affiliation(s)
- Mitra-Sadat Sadat-Shirazi
- Department of Neuroscience, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran,Genetics Laboratory, Iranian National Center for Addiction Studies (INCAS), Tehran University of Medical Sciences, Tehran, Iran
| | - Nasim Vousooghi
- Department of Neuroscience, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran,Genetics Laboratory, Iranian National Center for Addiction Studies (INCAS), Tehran University of Medical Sciences, Tehran, Iran,Research Center for Cognitive and Behavioral Sciences, Tehran University of Medical Sciences, Tehran, Iran,Corresponding author: Nasim Vousooghi, Pharm D, PhD; Department of Neuroscience, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, PO Box 1417755469, Tehran, Iran; Phone: +98 21 8899 1118; Fax: +98 21 8899 1117; E-mail:
| | - Bentolhoda Alizadeh
- Department of Biology, Pharmaceutical Sciences Branch, Islamic Azad University, Tehran, Iran
| | - Seyed Mohammad Makki
- Department of Psychiatry, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | | | - Shahrzad Nazari
- Genetics Laboratory, Iranian National Center for Addiction Studies (INCAS), Tehran University of Medical Sciences, Tehran, Iran
| | - Mohammad Reza Zarrindast
- Genetics Laboratory, Iranian National Center for Addiction Studies (INCAS), Tehran University of Medical Sciences, Tehran, Iran,Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran,School of Cognitive Sciences, Institute for Studies in Theoretical Physics and Mathematics, Tehran, Iran,Institute for Cognitive Science Studies, Tehran, Iran
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Carta M, Srikumar BN, Gorlewicz A, Rebola N, Mulle C. Activity-dependent control of NMDA receptor subunit composition at hippocampal mossy fibre synapses. J Physiol 2018; 596:703-716. [PMID: 29218821 DOI: 10.1113/jp275226] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 11/27/2017] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS CA3 pyramidal cells display input-specific differences in the subunit composition of synaptic NMDA receptors (NMDARs). Although at low density, GluN2B contributes significantly to NMDAR-mediated EPSCs at mossy fibre synapses. Long-term potentiation (LTP) of NMDARs triggers a modification in the subunit composition of synaptic NMDARs by insertion of GluN2B. GluN2B subunits are essential for the expression of LTP of NMDARs at mossy fibre synapses. ABSTRACT Single neurons express NMDA receptors (NMDARs) with distinct subunit composition and biophysical properties that can be segregated in an input-specific manner. The dynamic control of the heterogeneous distribution of synaptic NMDARs is crucial to control input-dependent synaptic integration and plasticity. In hippocampal CA3 pyramidal cells from mice of both sexes, we found that mossy fibre (MF) synapses display a markedly lower proportion of GluN2B-containing NMDARs than associative/commissural synapses. The mechanism involved in such heterogeneous distribution of GluN2B subunits is not known. Here we show that long-term potentiation (LTP) of NMDARs, which is selectively expressed at MF-CA3 pyramidal cell synapses, triggers a modification in the subunit composition of synaptic NMDARs by insertion of GluN2B. This activity-dependent recruitment of GluN2B at mature MF-CA3 pyramidal cell synapses contrasts with the removal of GluN2B subunits at other glutamatergic synapses during development and in response to activity. Furthermore, although expressed at low levels, GluN2B is necessary for the expression of LTP of NMDARs at MF-CA3 pyramidal cell synapses. Altogether, we reveal a previously unknown activity-dependent regulation and function of GluN2B subunits that may contribute to the heterogeneous plasticity induction rules in CA3 pyramidal cells.
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Affiliation(s)
- Mario Carta
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, F-33000, Bordeaux, France
| | - Bettadapura N Srikumar
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, F-33000, Bordeaux, France
| | - Adam Gorlewicz
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, F-33000, Bordeaux, France
| | - Nelson Rebola
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, F-33000, Bordeaux, France
| | - Christophe Mulle
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, F-33000, Bordeaux, France
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Ebrahimi-Ghiri M, Rostampour M, Jamshidi-Mehr M, Nasehi M, Zarrindast MR. Role of CA1 GABAA and GABAB receptors on learning deficit induced by D-AP5 in passive avoidance step-through task. Brain Res 2018; 1678:164-173. [DOI: 10.1016/j.brainres.2017.10.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 06/24/2017] [Accepted: 10/03/2017] [Indexed: 10/18/2022]
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Lucchese G. From Toxoplasmosis to Schizophrenia via NMDA Dysfunction: Peptide Overlap between Toxoplasma gondii and N-Methyl-d-Aspartate Receptors As a Potential Mechanistic Link. Front Psychiatry 2017; 8:37. [PMID: 28360866 PMCID: PMC5350139 DOI: 10.3389/fpsyt.2017.00037] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Accepted: 02/27/2017] [Indexed: 12/24/2022] Open
Abstract
The present work aims at investigating how Toxoplasma gondii (T. gondii) infection may be linked to N-methyl-d-aspartate receptor (NMDAR) dysfunction in schizophrenia and related disorders and puts forward the hypothesis that immune responses against T. gondii may involve NMDARs. Indeed, the analysis of the protozoan proteome and NMDAR subunits for peptide commonalities shows a massive peptide overlap and supports the possibility that anti-T. gondii immune responses raised during active protozoan infection may cross-react with host NMDARs, determining disruption of neural circuits and cognitive deficits. In particular, the NMDA 2D subunit, which is mainly expressed in parvalbumin-positive interneurons, appears to be a hotspot for potential T. gondii-induced cross-reactive immune attacks.
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Perszyk RE, DiRaddo JO, Strong KL, Low CM, Ogden KK, Khatri A, Vargish GA, Pelkey KA, Tricoire L, Liotta DC, Smith Y, McBain CJ, Traynelis SF. GluN2D-Containing N-methyl-d-Aspartate Receptors Mediate Synaptic Transmission in Hippocampal Interneurons and Regulate Interneuron Activity. Mol Pharmacol 2016; 90:689-702. [PMID: 27625038 DOI: 10.1124/mol.116.105130] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Accepted: 09/12/2016] [Indexed: 12/29/2022] Open
Abstract
N-methyl-d-aspartate receptors (NMDARs) are ionotropic glutamatergic receptors that have been implicated in learning, development, and neuropathological conditions. They are typically composed of GluN1 and GluN2A-D subunits. Whereas a great deal is known about the role of GluN2A- and GluN2B-containing NMDARs, much less is known about GluN2D-containing NMDARs. Here we explore the subunit composition of synaptic NMDARs on hippocampal interneurons. GluN2D mRNA was detected by single-cell PCR and in situ hybridization in diverse interneuron subtypes in the CA1 region of the hippocampus. The GluN2D subunit was detectable by immunoblotting and immunohistochemistry in all subfields of the hippocampus in young and adult mice. In whole-cell patch-clamp recordings from acute hippocampal slices, (+)-CIQ, the active enantiomer of the positive allosteric modulator CIQ, significantly enhanced the amplitude of the NMDAR component of miniature excitatory postsynaptic currents (mEPSCs) in CA1 interneurons but not in pyramidal cells. (+)-CIQ had no effect in slices from Grin2d-/- mice, suggesting that GluN2D-containing NMDARs participate in excitatory synaptic transmission onto hippocampal interneurons. The time course of the NMDAR component of the mEPSC was unaffected by (+)-CIQ potentiation and was not accelerated in slices from Grin2d-/- mice compared with wild-type, suggesting that GluN2D does not detectably slow the NMDAR EPSC time course at this age. (+)-CIQ increased the activity of CA1 interneurons as detected by the rate and net charge transfer of spontaneous inhibitory postsynaptic currents (sIPSCs) recorded from CA1 pyramidal cells. These data provide evidence that interneurons contain synaptic NMDARs possessing a GluN2D subunit, which can influence interneuron function and signal processing.
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Affiliation(s)
- Riley E Perszyk
- Departments of Pharmacology (R.E.P., J.O.D., K.K.O., A.K., S.F.T.), Chemistry (J.O.D., K.L.S., D.C.L.), Neurology (Y.S.), Yerkes National Primate Research Center (Y.S.), and Morris K. Udall Center of Excellence for Parkinson's Disease Research (Y.S.), Emory University, Atlanta, Georgia; Departments of Pharmacology and Anaesthesiology (C.-M.L.), Yong Loo Lin School of Medicine, National University of Singapore, Singapore; and Program in Developmental Neurobiology, Eunice Kennedy-Shriver National Institute of Child Health and Human Development (G.A.V., K.A.P., L.T., C.J.M.), National Institutes of Health, Bethesda, Maryland
| | - John O DiRaddo
- Departments of Pharmacology (R.E.P., J.O.D., K.K.O., A.K., S.F.T.), Chemistry (J.O.D., K.L.S., D.C.L.), Neurology (Y.S.), Yerkes National Primate Research Center (Y.S.), and Morris K. Udall Center of Excellence for Parkinson's Disease Research (Y.S.), Emory University, Atlanta, Georgia; Departments of Pharmacology and Anaesthesiology (C.-M.L.), Yong Loo Lin School of Medicine, National University of Singapore, Singapore; and Program in Developmental Neurobiology, Eunice Kennedy-Shriver National Institute of Child Health and Human Development (G.A.V., K.A.P., L.T., C.J.M.), National Institutes of Health, Bethesda, Maryland
| | - Katie L Strong
- Departments of Pharmacology (R.E.P., J.O.D., K.K.O., A.K., S.F.T.), Chemistry (J.O.D., K.L.S., D.C.L.), Neurology (Y.S.), Yerkes National Primate Research Center (Y.S.), and Morris K. Udall Center of Excellence for Parkinson's Disease Research (Y.S.), Emory University, Atlanta, Georgia; Departments of Pharmacology and Anaesthesiology (C.-M.L.), Yong Loo Lin School of Medicine, National University of Singapore, Singapore; and Program in Developmental Neurobiology, Eunice Kennedy-Shriver National Institute of Child Health and Human Development (G.A.V., K.A.P., L.T., C.J.M.), National Institutes of Health, Bethesda, Maryland
| | - Chian-Ming Low
- Departments of Pharmacology (R.E.P., J.O.D., K.K.O., A.K., S.F.T.), Chemistry (J.O.D., K.L.S., D.C.L.), Neurology (Y.S.), Yerkes National Primate Research Center (Y.S.), and Morris K. Udall Center of Excellence for Parkinson's Disease Research (Y.S.), Emory University, Atlanta, Georgia; Departments of Pharmacology and Anaesthesiology (C.-M.L.), Yong Loo Lin School of Medicine, National University of Singapore, Singapore; and Program in Developmental Neurobiology, Eunice Kennedy-Shriver National Institute of Child Health and Human Development (G.A.V., K.A.P., L.T., C.J.M.), National Institutes of Health, Bethesda, Maryland
| | - Kevin K Ogden
- Departments of Pharmacology (R.E.P., J.O.D., K.K.O., A.K., S.F.T.), Chemistry (J.O.D., K.L.S., D.C.L.), Neurology (Y.S.), Yerkes National Primate Research Center (Y.S.), and Morris K. Udall Center of Excellence for Parkinson's Disease Research (Y.S.), Emory University, Atlanta, Georgia; Departments of Pharmacology and Anaesthesiology (C.-M.L.), Yong Loo Lin School of Medicine, National University of Singapore, Singapore; and Program in Developmental Neurobiology, Eunice Kennedy-Shriver National Institute of Child Health and Human Development (G.A.V., K.A.P., L.T., C.J.M.), National Institutes of Health, Bethesda, Maryland
| | - Alpa Khatri
- Departments of Pharmacology (R.E.P., J.O.D., K.K.O., A.K., S.F.T.), Chemistry (J.O.D., K.L.S., D.C.L.), Neurology (Y.S.), Yerkes National Primate Research Center (Y.S.), and Morris K. Udall Center of Excellence for Parkinson's Disease Research (Y.S.), Emory University, Atlanta, Georgia; Departments of Pharmacology and Anaesthesiology (C.-M.L.), Yong Loo Lin School of Medicine, National University of Singapore, Singapore; and Program in Developmental Neurobiology, Eunice Kennedy-Shriver National Institute of Child Health and Human Development (G.A.V., K.A.P., L.T., C.J.M.), National Institutes of Health, Bethesda, Maryland
| | - Geoffrey A Vargish
- Departments of Pharmacology (R.E.P., J.O.D., K.K.O., A.K., S.F.T.), Chemistry (J.O.D., K.L.S., D.C.L.), Neurology (Y.S.), Yerkes National Primate Research Center (Y.S.), and Morris K. Udall Center of Excellence for Parkinson's Disease Research (Y.S.), Emory University, Atlanta, Georgia; Departments of Pharmacology and Anaesthesiology (C.-M.L.), Yong Loo Lin School of Medicine, National University of Singapore, Singapore; and Program in Developmental Neurobiology, Eunice Kennedy-Shriver National Institute of Child Health and Human Development (G.A.V., K.A.P., L.T., C.J.M.), National Institutes of Health, Bethesda, Maryland
| | - Kenneth A Pelkey
- Departments of Pharmacology (R.E.P., J.O.D., K.K.O., A.K., S.F.T.), Chemistry (J.O.D., K.L.S., D.C.L.), Neurology (Y.S.), Yerkes National Primate Research Center (Y.S.), and Morris K. Udall Center of Excellence for Parkinson's Disease Research (Y.S.), Emory University, Atlanta, Georgia; Departments of Pharmacology and Anaesthesiology (C.-M.L.), Yong Loo Lin School of Medicine, National University of Singapore, Singapore; and Program in Developmental Neurobiology, Eunice Kennedy-Shriver National Institute of Child Health and Human Development (G.A.V., K.A.P., L.T., C.J.M.), National Institutes of Health, Bethesda, Maryland
| | - Ludovic Tricoire
- Departments of Pharmacology (R.E.P., J.O.D., K.K.O., A.K., S.F.T.), Chemistry (J.O.D., K.L.S., D.C.L.), Neurology (Y.S.), Yerkes National Primate Research Center (Y.S.), and Morris K. Udall Center of Excellence for Parkinson's Disease Research (Y.S.), Emory University, Atlanta, Georgia; Departments of Pharmacology and Anaesthesiology (C.-M.L.), Yong Loo Lin School of Medicine, National University of Singapore, Singapore; and Program in Developmental Neurobiology, Eunice Kennedy-Shriver National Institute of Child Health and Human Development (G.A.V., K.A.P., L.T., C.J.M.), National Institutes of Health, Bethesda, Maryland
| | - Dennis C Liotta
- Departments of Pharmacology (R.E.P., J.O.D., K.K.O., A.K., S.F.T.), Chemistry (J.O.D., K.L.S., D.C.L.), Neurology (Y.S.), Yerkes National Primate Research Center (Y.S.), and Morris K. Udall Center of Excellence for Parkinson's Disease Research (Y.S.), Emory University, Atlanta, Georgia; Departments of Pharmacology and Anaesthesiology (C.-M.L.), Yong Loo Lin School of Medicine, National University of Singapore, Singapore; and Program in Developmental Neurobiology, Eunice Kennedy-Shriver National Institute of Child Health and Human Development (G.A.V., K.A.P., L.T., C.J.M.), National Institutes of Health, Bethesda, Maryland
| | - Yoland Smith
- Departments of Pharmacology (R.E.P., J.O.D., K.K.O., A.K., S.F.T.), Chemistry (J.O.D., K.L.S., D.C.L.), Neurology (Y.S.), Yerkes National Primate Research Center (Y.S.), and Morris K. Udall Center of Excellence for Parkinson's Disease Research (Y.S.), Emory University, Atlanta, Georgia; Departments of Pharmacology and Anaesthesiology (C.-M.L.), Yong Loo Lin School of Medicine, National University of Singapore, Singapore; and Program in Developmental Neurobiology, Eunice Kennedy-Shriver National Institute of Child Health and Human Development (G.A.V., K.A.P., L.T., C.J.M.), National Institutes of Health, Bethesda, Maryland
| | - Chris J McBain
- Departments of Pharmacology (R.E.P., J.O.D., K.K.O., A.K., S.F.T.), Chemistry (J.O.D., K.L.S., D.C.L.), Neurology (Y.S.), Yerkes National Primate Research Center (Y.S.), and Morris K. Udall Center of Excellence for Parkinson's Disease Research (Y.S.), Emory University, Atlanta, Georgia; Departments of Pharmacology and Anaesthesiology (C.-M.L.), Yong Loo Lin School of Medicine, National University of Singapore, Singapore; and Program in Developmental Neurobiology, Eunice Kennedy-Shriver National Institute of Child Health and Human Development (G.A.V., K.A.P., L.T., C.J.M.), National Institutes of Health, Bethesda, Maryland
| | - Stephen F Traynelis
- Departments of Pharmacology (R.E.P., J.O.D., K.K.O., A.K., S.F.T.), Chemistry (J.O.D., K.L.S., D.C.L.), Neurology (Y.S.), Yerkes National Primate Research Center (Y.S.), and Morris K. Udall Center of Excellence for Parkinson's Disease Research (Y.S.), Emory University, Atlanta, Georgia; Departments of Pharmacology and Anaesthesiology (C.-M.L.), Yong Loo Lin School of Medicine, National University of Singapore, Singapore; and Program in Developmental Neurobiology, Eunice Kennedy-Shriver National Institute of Child Health and Human Development (G.A.V., K.A.P., L.T., C.J.M.), National Institutes of Health, Bethesda, Maryland
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France G, Fernández-Fernández D, Burnell ES, Irvine MW, Monaghan DT, Jane DE, Bortolotto ZA, Collingridge GL, Volianskis A. Multiple roles of GluN2B-containing NMDA receptors in synaptic plasticity in juvenile hippocampus. Neuropharmacology 2016; 112:76-83. [PMID: 27523302 PMCID: PMC5084684 DOI: 10.1016/j.neuropharm.2016.08.010] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 08/09/2016] [Accepted: 08/10/2016] [Indexed: 11/28/2022]
Abstract
In the CA1 area of the hippocampus N-methyl-d-aspartate receptors (NMDARs) mediate the induction of long-term depression (LTD), short-term potentiation (STP) and long-term potentiation (LTP). All of these forms of synaptic plasticity can be readily studied in juvenile hippocampal slices but the involvement of particular NMDAR subunits in the induction of these different forms of synaptic plasticity is currently unclear. Here, using NVP-AAM077, Ro 25-6981 and UBP145 to target GluN2A-, 2B- and 2D-containing NMDARs respectively, we show that GluN2B-containing NMDARs (GluN2B) are involved in the induction of LTD, STP and LTP in slices prepared from P14 rat hippocampus. A concentration of Ro (1 μM) that selectively blocks GluN2B-containing diheteromers is able to block LTD. It also inhibits a component of STP without affecting LTP. A higher concentration of Ro (10 μM), that also inhibits GluN2A/B triheteromers, blocks LTP. UBP145 selectively inhibits the Ro-sensitive component of STP whereas NVP inhibits LTP. These data are consistent with a role of GluN2B diheretomers in LTD, a role of both GluN2B- and GluN2D- containing NMDARs in STP and a role of GluN2A/B triheteromers in LTP. This article is part of the Special Issue entitled ‘Ionotropic glutamate receptors’. Inhibition of GluN2Bs in P14 is sufficient for blockade of NMDAR-LTD. GluN2A and GluN2D subunits are not required for the induction of LTD. Induction of STP involves GluN2B and GluN2D subunits. Induction of LTP depends on GluN2A/2B triheteromers.
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Affiliation(s)
- Grace France
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - Diego Fernández-Fernández
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - Erica S Burnell
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - Mark W Irvine
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - Daniel T Monaghan
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, USA
| | - David E Jane
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - Zuner A Bortolotto
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - Graham L Collingridge
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK; Dept Physiology, University of Toronto and Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Canada
| | - Arturas Volianskis
- Centre for Synaptic Plasticity, 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, UK.
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9
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Active dendrites regulate the impact of gliotransmission on rat hippocampal pyramidal neurons. Proc Natl Acad Sci U S A 2016; 113:E3280-9. [PMID: 27217559 DOI: 10.1073/pnas.1522180113] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
An important consequence of gliotransmission, a signaling mechanism that involves glial release of active transmitter molecules, is its manifestation as N-methyl-d-aspartate receptor (NMDAR)-dependent slow inward currents in neurons. However, the intraneuronal spatial dynamics of these events or the role of active dendrites in regulating their amplitude and spatial spread have remained unexplored. Here, we used somatic and/or dendritic recordings from rat hippocampal pyramidal neurons and demonstrate that a majority of NMDAR-dependent spontaneous slow excitatory potentials (SEP) originate at dendritic locations and are significantly attenuated through their propagation across the neuronal arbor. We substantiated the astrocytic origin of SEPs through paired neuron-astrocyte recordings, where we found that specific infusion of inositol trisphosphate (InsP3) into either distal or proximal astrocytes enhanced the amplitude and frequency of neuronal SEPs. Importantly, SEPs recorded after InsP3 infusion into distal astrocytes exhibited significantly slower kinetics compared with those recorded after proximal infusion. Furthermore, using neuron-specific infusion of pharmacological agents and morphologically realistic conductance-based computational models, we demonstrate that dendritically expressed hyperpolarization-activated cyclic-nucleotide-gated (HCN) and transient potassium channels play critical roles in regulating the strength, kinetics, and compartmentalization of neuronal SEPs. Finally, through the application of subtype-specific receptor blockers during paired neuron-astrocyte recordings, we provide evidence that GluN2B- and GluN2D-containing NMDARs predominantly mediate perisomatic and dendritic SEPs, respectively. Our results unveil an important role for active dendrites in regulating the impact of gliotransmission on neurons and suggest astrocytes as a source of dendritic plateau potentials that have been implicated in localized plasticity and place cell formation.
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Muniz BG, Isokawa M. Ghrelin receptor activity amplifies hippocampal N-methyl-d-aspartate receptor-mediated postsynaptic currents and increases phosphorylation of the GluN1 subunit at Ser896 and Ser897. Eur J Neurosci 2015; 42:3045-53. [PMID: 26490687 DOI: 10.1111/ejn.13107] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 10/13/2015] [Accepted: 10/15/2015] [Indexed: 12/31/2022]
Abstract
Although ghrelin and its cognate receptor growth hormone secretagogue receptor (GHSR1a) are highly localized in the hypothalamic nuclei for the regulation of metabolic states and feeding, GHSR1a is also highly localized in the hippocampus, suggesting its involvement in extra-hypothalamic functions. Indeed, exogenous application of ghrelin has been reported to improve hippocampal learning and memory. However, the underlying mechanism of ghrelin regulation of hippocampal functions is poorly understood. Here, we report ghrelin-promoted phosphorylation of GluN1 and amplified N-methyl-d-aspartate receptor (NMDAR)-mediated excitatory postsynaptic currents in the CA1 pyramidal cells of the hippocampus in slice preparations. The ghrelin-induced responses were sensitive to a GHSR1a antagonist and inverse agonist, and were absent in GHSR1a homozygous knock-out mice. These results indicated that activation of GHSR1a was critical in the ghrelin-induced enhancement of the NMDAR function. Interestingly, heterozygous mouse hippocampi were also insensitive to ghrelin treatment, suggesting that a slight reduction in the availability of GHSR1a may be sufficient to negate the effect of ghrelin on GluN1 phosphorylation and NMDAR channel activities. In addition, NMDAR-mediated spike currents, which are of dendritic origin, were blocked by the GHSR1a antagonist, suggesting the presence of GHSR1a on the pyramidal cell dendrites in physical proximity to NMDAR. Together with our findings on the localization of GHSR1a in the CA1 region of the hippocampus, which was shown by fluorescent ghrelin binding, immunoreactivity, and enhanced green fluorescent protein reporter gene expression, we conclude that the activation of GHSR1a favours rapid modulation of the NMDAR-mediated glutamatergic synaptic transmission by phosphorylating GluN1 in the hippocampus.
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Affiliation(s)
- Brandon G Muniz
- Department of Health and Biomedical Sciences, The University of Texas Rio Grande Valley, One West University Boulevard, Brownsville, TX, 78520, USA
| | - Masako Isokawa
- Department of Health and Biomedical Sciences, The University of Texas Rio Grande Valley, One West University Boulevard, Brownsville, TX, 78520, USA
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11
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Chen P, Song J, Luo L, Cheng Q, Xiao H, Gong S. Gene expression of NMDA and AMPA receptors in different facial motor neurons. Laryngoscope 2015; 126:E6-11. [DOI: 10.1002/lary.25575] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Revised: 07/21/2015] [Accepted: 07/23/2015] [Indexed: 12/17/2022]
Affiliation(s)
- Pei Chen
- Department of Otolaryngology-Head and Neck Surgery; Union Hospital, Tongji Medical College, Huazhong University of Science and Technology; Wuhan
| | - Jun Song
- Department of Otolaryngology-Head and Neck Surgery; Wuxi Third Hospital; Wuxi
| | - Linghui Luo
- Department of Otolaryngology-Head and Neck Surgery; Union Hospital, Tongji Medical College, Huazhong University of Science and Technology; Wuhan
| | - Qing Cheng
- Department of Otolaryngology-Head and Neck Surgery; Union Hospital, Tongji Medical College, Huazhong University of Science and Technology; Wuhan
| | - Hongjun Xiao
- Department of Otolaryngology-Head and Neck Surgery; Union Hospital, Tongji Medical College, Huazhong University of Science and Technology; Wuhan
| | - Shusheng Gong
- Department of Otolaryngology-Head and Neck Surgery; Beijing Friendship Hospital, Capital Medical University; Beijing China
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12
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Li X, Zhang YY, Chen ZQ, Jiang ZL, Sun L, Xu LH, Yang Y, Zhang YF. D-serine-induced inactivation of NMDA receptors in cultured rat hippocampal neurons expressing NR2A subunits is Ca2+-dependent. CNS Neurosci Ther 2014; 20:951-60. [PMID: 25042179 DOI: 10.1111/cns.12308] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Revised: 06/23/2014] [Accepted: 06/27/2014] [Indexed: 11/29/2022] Open
Abstract
AIMS Our previous studies indicate that glycine can inhibit N-methyl-D-aspartate receptor (NMDAR) responses induced by high concentrations of NMDA in rat hippocampal neurons. The present study was designed to observe whether D-serine induces inactivation of NMDARs in cultured rat hippocampal neurons and to investigate the underlying mechanisms of this effect. METHODS Cell culture, whole-cell patch-clamp electrophysiology, Ca(2+) imaging, immunohistochemistry, and Western blot analysis were used. RESULTS We found that the peak current and Ca(2+) influx evoked by 30 μM NMDA were increased by co-application of D-serine, but those evoked by 300 μM NMDA were reduced dose-dependently by co-application of D-serine. However, the inhibitory effect of D-serine on NMDAR responses was reversed by ZnCl2 (30 nM), an inhibitor of the NR2A subunit, but was less influenced by ifenprodil (10 μM), an NR2B inhibitor. In addition, the inhibitory effect of D-serine was not detected in young hippocampal neurons that expressed less of the NR2A subunits and reversed in the presence of 10 mM BAPTA. CONCLUSIONS D-serine can also induce inactivation of NMDARs, the NR2A subunit is required for the induction of this effect, and this inactivation is Ca(2+)-dependent in nature. This action of D-serine is hypothesized to play a neuroprotective role upon a sustained large glutamate insult to the brain.
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Affiliation(s)
- Xia Li
- Department of Neuropharmacology, Institute of Nautical Medicine, Nantong University, Jiangsu, China
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13
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Mirante O, Brandalise F, Bohacek J, Mansuy IM. Distinct molecular components for thalamic- and cortical-dependent plasticity in the lateral amygdala. Front Mol Neurosci 2014; 7:62. [PMID: 25071439 PMCID: PMC4080466 DOI: 10.3389/fnmol.2014.00062] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 06/16/2014] [Indexed: 01/05/2023] Open
Abstract
N-methyl-D-aspartate receptor (NMDAR)-dependent long-term depression (LTD) in the lateral nucleus of the amygdala (LA) is a form of synaptic plasticity thought to be a cellular substrate for the extinction of fear memory. The LA receives converging inputs from the sensory thalamus and neocortex that are weakened following fear extinction. Combining field and patch-clamp electrophysiological recordings in mice, we show that paired-pulse low-frequency stimulation can induce a robust LTD at thalamic and cortical inputs to LA, and we identify different underlying molecular components at these pathways. We show that while LTD depends on NMDARs and activation of the protein phosphatases PP2B and PP1 at both pathways, it requires NR2B-containing NMDARs at the thalamic pathway, but NR2C/D-containing NMDARs at the cortical pathway. LTD appears to be induced post-synaptically at the thalamic input but presynaptically at the cortical input, since post-synaptic calcium chelation and NMDAR blockade prevent thalamic but not cortical LTD. These results highlight distinct molecular features of LTD in LA that may be relevant for traumatic memory and its erasure, and for pathologies such as post-traumatic stress disorder (PTSD).
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Affiliation(s)
- Osvaldo Mirante
- Brain Research Institute, Medical Faculty, University Zürich Zürich, Switzerland ; Department of Health Science and Technology, Swiss Federal Institute of Technology Zürich, Switzerland
| | - Federico Brandalise
- Brain Research Institute, Medical Faculty, University Zürich Zürich, Switzerland
| | - Johannes Bohacek
- Brain Research Institute, Medical Faculty, University Zürich Zürich, Switzerland ; Department of Health Science and Technology, Swiss Federal Institute of Technology Zürich, Switzerland
| | - Isabelle M Mansuy
- Brain Research Institute, Medical Faculty, University Zürich Zürich, Switzerland ; Department of Health Science and Technology, Swiss Federal Institute of Technology Zürich, Switzerland
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Oda Y, Kodama S, Tsuchiya S, Inoue M, Miyakawa H. Intracellular calcium elevation during plateau potentials mediated by extrasynaptic NMDA receptor activation in rat hippocampal CA1 pyramidal neurons is primarily due to calcium entry through voltage-gated calcium channels. Eur J Neurosci 2014; 39:1613-23. [DOI: 10.1111/ejn.12555] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 02/04/2014] [Accepted: 02/11/2014] [Indexed: 12/21/2022]
Affiliation(s)
- Yoshiaki Oda
- Laboratory of Cellular Neurobiology; School of Life Sciences; Tokyo University of Pharmacy and Life Sciences; Hachioji Tokyo 192-0392 Japan
| | - Satoshi Kodama
- Laboratory of Cellular Neurobiology; School of Life Sciences; Tokyo University of Pharmacy and Life Sciences; Hachioji Tokyo 192-0392 Japan
| | - Sadahiro Tsuchiya
- Laboratory of Cellular Neurobiology; School of Life Sciences; Tokyo University of Pharmacy and Life Sciences; Hachioji Tokyo 192-0392 Japan
| | - Masashi Inoue
- Laboratory of Cellular Neurobiology; School of Life Sciences; Tokyo University of Pharmacy and Life Sciences; Hachioji Tokyo 192-0392 Japan
| | - Hiroyoshi Miyakawa
- Laboratory of Cellular Neurobiology; School of Life Sciences; Tokyo University of Pharmacy and Life Sciences; Hachioji Tokyo 192-0392 Japan
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15
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Catts VS, Fung SJ, Long LE, Joshi D, Vercammen A, Allen KM, Fillman SG, Rothmond DA, Sinclair D, Tiwari Y, Tsai SY, Weickert TW, Shannon Weickert C. Rethinking schizophrenia in the context of normal neurodevelopment. Front Cell Neurosci 2013; 7:60. [PMID: 23720610 PMCID: PMC3654207 DOI: 10.3389/fncel.2013.00060] [Citation(s) in RCA: 144] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Accepted: 04/16/2013] [Indexed: 01/11/2023] Open
Abstract
The schizophrenia brain is differentiated from the normal brain by subtle changes, with significant overlap in measures between normal and disease states. For the past 25 years, schizophrenia has increasingly been considered a neurodevelopmental disorder. This frame of reference challenges biological researchers to consider how pathological changes identified in adult brain tissue can be accounted for by aberrant developmental processes occurring during fetal, childhood, or adolescent periods. To place schizophrenia neuropathology in a neurodevelopmental context requires solid, scrutinized evidence of changes occurring during normal development of the human brain, particularly in the cortex; however, too often data on normative developmental change are selectively referenced. This paper focuses on the development of the prefrontal cortex and charts major molecular, cellular, and behavioral events on a similar time line. We first consider the time at which human cognitive abilities such as selective attention, working memory, and inhibitory control mature, emphasizing that attainment of full adult potential is a process requiring decades. We review the timing of neurogenesis, neuronal migration, white matter changes (myelination), and synapse development. We consider how molecular changes in neurotransmitter signaling pathways are altered throughout life and how they may be concomitant with cellular and cognitive changes. We end with a consideration of how the response to drugs of abuse changes with age. We conclude that the concepts around the timing of cortical neuronal migration, interneuron maturation, and synaptic regression in humans may need revision and include greater emphasis on the protracted and dynamic changes occurring in adolescence. Updating our current understanding of post-natal neurodevelopment should aid researchers in interpreting gray matter changes and derailed neurodevelopmental processes that could underlie emergence of psychosis.
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Affiliation(s)
- Vibeke S. Catts
- Schizophrenia Research Laboratory, Schizophrenia Research InstituteSydney, NSW, Australia
- Neuroscience Research AustraliaSydney, NSW, Australia
- School of Psychiatry, University of New South WalesSydney, NSW, Australia
| | - Samantha J. Fung
- Schizophrenia Research Laboratory, Schizophrenia Research InstituteSydney, NSW, Australia
- Neuroscience Research AustraliaSydney, NSW, Australia
- School of Psychiatry, University of New South WalesSydney, NSW, Australia
| | - Leonora E. Long
- Schizophrenia Research Laboratory, Schizophrenia Research InstituteSydney, NSW, Australia
- Neuroscience Research AustraliaSydney, NSW, Australia
- School of Medical Sciences, University of New South WalesSydney, NSW, Australia
| | - Dipesh Joshi
- Schizophrenia Research Laboratory, Schizophrenia Research InstituteSydney, NSW, Australia
- Neuroscience Research AustraliaSydney, NSW, Australia
- School of Psychiatry, University of New South WalesSydney, NSW, Australia
| | - Ans Vercammen
- Schizophrenia Research Laboratory, Schizophrenia Research InstituteSydney, NSW, Australia
- Neuroscience Research AustraliaSydney, NSW, Australia
- School of Psychiatry, University of New South WalesSydney, NSW, Australia
- School of Psychology, Australian Catholic UniversitySydney, NSW, Australia
| | - Katherine M. Allen
- Schizophrenia Research Laboratory, Schizophrenia Research InstituteSydney, NSW, Australia
- Neuroscience Research AustraliaSydney, NSW, Australia
- School of Psychiatry, University of New South WalesSydney, NSW, Australia
| | - Stu G. Fillman
- Schizophrenia Research Laboratory, Schizophrenia Research InstituteSydney, NSW, Australia
- Neuroscience Research AustraliaSydney, NSW, Australia
- School of Psychiatry, University of New South WalesSydney, NSW, Australia
| | - Debora A. Rothmond
- Schizophrenia Research Laboratory, Schizophrenia Research InstituteSydney, NSW, Australia
- Neuroscience Research AustraliaSydney, NSW, Australia
| | - Duncan Sinclair
- Schizophrenia Research Laboratory, Schizophrenia Research InstituteSydney, NSW, Australia
- Neuroscience Research AustraliaSydney, NSW, Australia
- School of Psychiatry, University of New South WalesSydney, NSW, Australia
| | - Yash Tiwari
- Schizophrenia Research Laboratory, Schizophrenia Research InstituteSydney, NSW, Australia
- Neuroscience Research AustraliaSydney, NSW, Australia
- School of Medical Sciences, University of New South WalesSydney, NSW, Australia
| | - Shan-Yuan Tsai
- Schizophrenia Research Laboratory, Schizophrenia Research InstituteSydney, NSW, Australia
- Neuroscience Research AustraliaSydney, NSW, Australia
- School of Psychiatry, University of New South WalesSydney, NSW, Australia
| | - Thomas W. Weickert
- Schizophrenia Research Laboratory, Schizophrenia Research InstituteSydney, NSW, Australia
- Neuroscience Research AustraliaSydney, NSW, Australia
- School of Psychiatry, University of New South WalesSydney, NSW, Australia
| | - Cynthia Shannon Weickert
- Schizophrenia Research Laboratory, Schizophrenia Research InstituteSydney, NSW, Australia
- Neuroscience Research AustraliaSydney, NSW, Australia
- School of Psychiatry, University of New South WalesSydney, NSW, Australia
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MacDonald JF, Belrose JC, Xie YF, Jackson MF. Nonselective cation channels and links to hippocampal ischemia, aging, and dementia. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 961:433-47. [PMID: 23224901 DOI: 10.1007/978-1-4614-4756-6_37] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
Stroke is a very strong risk factor for dementia. Furthermore, ischemic stroke and Alzheimer's disease (AD) share a number of overlapping mechanisms of neuron loss and dysfunction, including those induced by the inappropriate activation of N-methyl-D-aspartate receptors (NMDARs). These receptors form a major subtype of excitatory glutamate receptor. They are nonselective cation channels with appreciable Ca(2+) permeability, and their overactivation leads to neurotoxicity in the cortex and hippocampus. NMDARs have therefore been therapeutic targets in both conditions, but they have failed in the treatment of stroke, and there is limited rationale for using them in treating AD. In this chapter, we discuss current understanding of subtypes of NMDARs and their potential roles in -ischemic stroke and AD. We also discuss the properties of several other nonselective cation channels, transient receptor potential melastatin 2 and 7 channels, and their implications in linking these conditions.
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Affiliation(s)
- John F MacDonald
- Department of Anatomy and Cell Biology, University of Western Ontario, London, ON, Canada.
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17
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Volianskis A, Bannister N, Collett VJ, Irvine MW, Monaghan DT, Fitzjohn SM, Jensen MS, Jane DE, Collingridge GL. Different NMDA receptor subtypes mediate induction of long-term potentiation and two forms of short-term potentiation at CA1 synapses in rat hippocampus in vitro. J Physiol 2013; 591:955-72. [PMID: 23230236 PMCID: PMC3591708 DOI: 10.1113/jphysiol.2012.247296] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Accepted: 12/07/2012] [Indexed: 12/16/2022] Open
Abstract
Potentiation at synapses between CA3 and the CA1 pyramidal neurons comprises both transient and sustained phases, commonly referred to as short-term potentiation (STP or transient LTP) and long-term potentiation (LTP), respectively. Here, we utilized four subtype-selective N-methyl-d-aspartate receptor (NMDAR) antagonists to investigate whether the induction of STP and LTP is dependent on the activation of different NMDAR subtypes. We find that the induction of LTP involves the activation of NMDARs containing both the GluN2A and the GluN2B subunits. Surprisingly, however, we find that STP can be separated into two components, the major form of which involves activation of NMDARs containing both GluN2B and GluN2D subunits. These data demonstrate that synaptic potentiation at CA1 synapses is more complex than is commonly thought, an observation that has major implications for understanding the role of NMDARs in cognition.
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Affiliation(s)
- Arturas Volianskis
- MRC Centre for Synaptic Plasticity, Departments of Anatomy, University of Bristol, Bristol, UK.
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18
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Thr136Ile polymorphism of human vesicular monoamine transporter-1 (SLC18A1 gene) influences its transport activity in vitro. Neural Plast 2013; 2012:945373. [PMID: 23213575 PMCID: PMC3504448 DOI: 10.1155/2012/945373] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2012] [Revised: 09/22/2012] [Accepted: 09/23/2012] [Indexed: 12/23/2022] Open
Abstract
The hippocampus has the extraordinary capacity to process and store information. Consequently, there is an intense interest in the mechanisms that underline learning and memory. Synaptic plasticity has been hypothesized to be the neuronal substrate for learning. Ca2+ and Ca2+-activated kinases control cellular processes of most forms of hippocampal synapse plasticity. In this paper, I aim to integrate our current understanding of Ca2+-mediated synaptic plasticity and metaplasticity in motivational and reward-related learning in the hippocampus. I will introduce two representative neuromodulators that are widely studied in reward-related learning (e.g., ghrelin and endocannabinoids) and show how they might contribute to hippocampal neuron activities and Ca2+-mediated signaling processes in synaptic plasticity. Additionally, I will discuss functional significance of these two systems and their signaling pathways for its relevance to maladaptive reward learning leading to addiction.
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19
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Pre- and postsynaptic localization of NMDA receptor subunits at hippocampal mossy fibre synapses. Neuroscience 2013; 230:139-50. [DOI: 10.1016/j.neuroscience.2012.10.061] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2012] [Revised: 10/25/2012] [Accepted: 10/26/2012] [Indexed: 11/20/2022]
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20
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Zhou HY, Chen SR, Pan HL. Targeting N-methyl-D-aspartate receptors for treatment of neuropathic pain. Expert Rev Clin Pharmacol 2012; 4:379-88. [PMID: 21686074 DOI: 10.1586/ecp.11.17] [Citation(s) in RCA: 136] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Neuropathic pain remains a major clinical problem and a therapeutic challenge because existing analgesics are often ineffective and can cause serious side effects. Increased N-methyl-d-aspartate receptor (NMDAR) activity contributes to central sensitization in certain types of neuropathic pain. NMDAR antagonists can reduce hyperalgesia and allodynia in animal models of neuropathic pain induced by nerve injury and diabetic neuropathy. Clinically used NMDAR antagonists, such as ketamine and dextromethorphan, are generally effective in patients with neuropathic pain, such as complex regional pain syndrome and painful diabetic neuropathy. However, patients with postherpetic neuralgia respond poorly to NMDAR antagonists. Recent studies on identifying NMDAR-interacting proteins and molecular mechanisms of increased NMDAR activity in neuropathic pain could facilitate the development of new drugs to attenuate abnormal NMDAR activity with minimal impairment of the physiological function of NMDARs. Combining NMDAR antagonists with other analgesics could also lead to better management of neuropathic pain without causing serious side effects.
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Affiliation(s)
- Hong-Yi Zhou
- Department of Anesthesiology and Perioperative Medicine, Unit 110, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA
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21
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Wang M, Chazot PL, Ali S, Duckett SF, Obrenovitch TP. Effects of NMDA receptor antagonists with different subtype selectivities on retinal spreading depression. Br J Pharmacol 2012; 165:235-44. [PMID: 21699507 PMCID: PMC3252980 DOI: 10.1111/j.1476-5381.2011.01553.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Revised: 05/12/2011] [Accepted: 06/05/2011] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE Spreading depression (SD) is a local, temporary disruption of cellular ionic homeostasis that propagates slowly across the cerebral cortex and other neural tissues such as the retina. Spreading depolarization associated with SD occurs in different types of stroke, and this phenomenon correlates also with the initiation of classical migraine aura. The aim of this study was to investigate how NMDA receptor antagonists with different subtype selectivity alter SD. EXPERIMENTAL APPROACH Immunoblotting was applied to the chick retina for NMDA receptor subunit protein analysis, and an efficient in vitro chick retinal model used with SD imaging for NMDA receptor pharmacology. KEY RESULTS The prominent NMDA receptor subtypes GluN1, GluN2A and GluN2B were found highly expressed in the chick retina. Nanomolar concentrations of NVP-AAM077 (GluN2A-preferring receptor antagonist) markedly suppressed high K(+) -induced SD; that is, ∼30 times more effectively than MK801. At sub-micromolar concentrations, Ro 25-6981 (GluN2B-preferring receptor antagonist) produced a moderate SD inhibition, whereas CP-101,606 (also GluN2B-preferring receptor antagonist) and UBP141 (GluN2C/2D-preferring receptor antagonist) had no effect. CONCLUSIONS AND IMPLICATIONS The expression of major NMDA receptor subtypes, GluN1, GluN2A and GluN2B in the chick retina makes them pertinent targets for pharmacological inhibition of SD. The high efficacy of NVP-AAM077 on SD inhibition suggests a critical role of GluN2A-containing receptors in SD genesis. Such high anti-SD potency suggests that NVP-AAM077, and other GluN2A-selective drug-like candidates, could be potential anti-migraine agents.
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Affiliation(s)
- Minyan Wang
- School of Pharmacy and Biomedical Sciences, University of Central Lancashire, Preston, UK.
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Gray JA, Shi Y, Usui H, During MJ, Sakimura K, Nicoll RA. Distinct modes of AMPA receptor suppression at developing synapses by GluN2A and GluN2B: single-cell NMDA receptor subunit deletion in vivo. Neuron 2011; 71:1085-101. [PMID: 21943605 DOI: 10.1016/j.neuron.2011.08.007] [Citation(s) in RCA: 218] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/09/2011] [Indexed: 01/23/2023]
Abstract
During development there is an activity-dependent switch in synaptic N-Methyl-D-aspartate (NMDA) receptor subunit composition from predominantly GluN2B to GluN2A, though the precise role of this switch remains unknown. By deleting GluN2 subunits in single neurons during synaptogenesis, we find that both GluN2B and GluN2A suppress AMPA receptor expression, albeit by distinct means. Similar to GluN1, GluN2B deletion increases the number of functional synapses, while GluN2A deletion increases the strength of unitary connections without affecting the number of functional synapses. We propose a model of excitatory synapse maturation in which baseline activation of GluN2B-containing receptors prevents premature synapse maturation until correlated activity allows induction of functional synapses. This activity also triggers the switch to GluN2A, which dampens further potentiation. Furthermore, we analyze the subunit composition of synaptic NMDA receptors in CA1 pyramidal cells, provide electrophysiological evidence for a large population of synaptic triheteromeric receptors, and estimate the subunit-dependent open probability.
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Affiliation(s)
- John A Gray
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94143, USA
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Chen HH, Lin YR, Chan MH. Toluene exposure during brain growth spurt and adolescence produces differential effects on N-methyl-D-aspartate receptor-mediated currents in rat hippocampus. Toxicol Lett 2011; 205:336-40. [PMID: 21726610 DOI: 10.1016/j.toxlet.2011.06.026] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Revised: 06/16/2011] [Accepted: 06/18/2011] [Indexed: 11/25/2022]
Abstract
Toluene, an industrial organic solvent, is voluntarily inhaled as drug of abuse. Because inhibition of N-methyl-d-aspartate (NMDA) receptors is one of the possible mechanisms underlying developmental neurotoxicity of toluene, the purpose of the present study was to examine the effects of toluene exposure during two major neurodevelopmental stages, brain growth spurt and adolescence, on NMDA receptor-mediated current. Rats were administered with toluene (500 mg/kg, i.p.) or corn oil daily over postnatal days (PN) 4-9 (brain growth spurt) or PN 21-26 (early adolescence). Intracellular electrophysiological recordings employing in CA1 pyramidal neurons in the hippocampal slices were performed during PN 30-38. Toluene exposure during brain growth spurt enhanced NMDA receptor-mediated excitatory postsynaptic currents (EPSCs) by electrical stimulation, but impaired the paired-pulse facilitation and NMDA response by exogenous application of NMDA. Toluene exposure during adolescence resulted in an increase in NMDA receptor-mediated EPSCs and a decrease in exogenous NMDA-induced currents, while lack of any effect on paired-pulse facilitation. These findings suggest that toluene exposure during brain growth spurt and adolescence might result in an increase in synaptic NMDA receptor responsiveness and a decrease in extrasynaptic NMDA receptor responsiveness, while only toluene exposure during brain growth spurt can produce presynaptic modulation in CA1 pyramidal neurons. The functional changes in NMDA receptor-mediated transmission underlying developmental toluene exposure may lead to the neurobehavioral disturbances.
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Affiliation(s)
- Hwei-Hsien Chen
- Institute of Pharmacology and Toxicology, Tzu Chi University, 701, Sec. 3, Chung Yang Rd., Hualien 97004, Taiwan
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McGuinness L, Taylor C, Taylor RDT, Yau C, Langenhan T, Hart ML, Christian H, Tynan PW, Donnelly P, Emptage NJ. Presynaptic NMDARs in the hippocampus facilitate transmitter release at theta frequency. Neuron 2011; 68:1109-27. [PMID: 21172613 DOI: 10.1016/j.neuron.2010.11.023] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/01/2010] [Indexed: 11/19/2022]
Abstract
A rise in [Ca(2+)](i) provides the trigger for neurotransmitter release at neuronal boutons. We have used confocal microscopy and Ca(2+) sensitive dyes to directly measure the action potential-evoked [Ca(2+)](i) in the boutons of Schaffer collaterals. This reveals that the trial-by-trial amplitude of the evoked Ca(2+) transient is bimodally distributed. We demonstrate that "large" Ca(2+) transients occur when presynaptic NMDA receptors are activated following transmitter release. Presynaptic NMDA receptor activation proves critical in producing facilitation of transmission at theta frequencies. Because large Ca(2+) transients "report" transmitter release, their frequency on a trial-by-trial basis can be used to estimate the probability of release, p(r). We use this novel estimator to show that p(r) increases following the induction of long-term potentiation.
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Affiliation(s)
- Lindsay McGuinness
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
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25
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Cuellar JN, Isokawa M. Ghrelin-induced activation of cAMP signal transduction and its negative regulation by endocannabinoids in the hippocampus. Neuropharmacology 2010; 60:842-51. [PMID: 21187104 DOI: 10.1016/j.neuropharm.2010.12.024] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2010] [Revised: 12/18/2010] [Accepted: 12/20/2010] [Indexed: 10/18/2022]
Abstract
Increasing evidence indicates that the gut peptide ghrelin facilitates learning behavior and memory tasks. The present study demonstrates a cellular signaling mechanism of ghrelin in the hippocampus. Ghrelin stimulated CREB (cAMP response-element binding protein) through the activation of cAMP, protein kinase A (PKA), and PKA-dependent phosphorylation of NR1 subunit of the NMDA receptor. Ghrelin increased phalloidin-binding to F-actin suggesting CREB-induced gene expression might include reorganization of cytoskeletal proteins. The effect was blocked by the antagonist of the ghrelin receptor in spite of the receptor's primary coupling to Gq proteins. We also discovered inhibitory effect of endocannabinoids on ghrelin-induced NR1 phosphorylation and CREB activity. 2-arachidonoylglycerol (2-AG) exerted its inhibitory effect in the Type 1 cannabinoid receptor (CB1R)-dependent manner, while anandamide's inhibitory effect persisted in the presence of antagonists of CB1R and the vanilloid receptor, suggesting that anandamide might directly inhibit NMDA receptor/channels. Our findings may explain how ghrelin and endocannabinoids regulate hippocampal appetitive learning and plasticity.
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Affiliation(s)
- Jacquelynn N Cuellar
- Department of Biological Sciences, The University of Texas at Brownsville, 80 Fort Brown, Brownsville, TX 78520, USA
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26
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Ortuño-Sahagún D, Rivera-Cervantes MC, Gudiño-Cabrera G, Junyent F, Verdaguer E, Auladell C, Pallàs M, Camins A, Beas-Zárate C. Microarray analysis of rat hippocampus exposed to excitotoxicity: reversal Na(+)/Ca(2+) exchanger NCX3 is overexpressed in glial cells. Hippocampus 2010; 22:128-40. [PMID: 20928830 DOI: 10.1002/hipo.20869] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/02/2010] [Indexed: 02/06/2023]
Abstract
Multiple factors are involved in the glutamate-induced excitotoxicity phenomenon, such as overload of ionotropic and metabotropic receptors, excess Ca(2+) influx, nitric oxide synthase activation, oxidative damage due to increase in free radicals, and release of endogenous polyamine, among others. In order to attempt a more integrated approach to address this issue, we established, by microarray analysis, the hippocampus gene expression profiles under glutamate-induced excitotoxicity conditions. Increased gene expression is mainly related to excitotoxicity (CaMKII, glypican 2, GFAP, NCX3, IL-2, and Gmeb2) or with cell damage response (dynactin and Ecel1). Several genes that augmented their expression are related to glutamatergic system modulation, in particular with NMDA receptor modulation and calcium homeostasis (IL-2, CaMKII, acrosin, Gmeb2, hAChE, Slc83a, and SP1 factor). Conversely, among genes that diminished their expression, we found the Syngap 1, which is downregulated by CaMKII, and the MHC II, which is downregulated by glutamate. Changes observed in gene expression induced by monosodium glutamate (MSG) neonatal treatment in the hippocampus are consistent with the activation of the mechanisms that modulate NMDA receptor function as well as with the implementation of plastic response to cell damage and intracellular calcium homeostasis. Regarding this aspect, we report here that NCX3/Slc8a3, a Na(+)/Ca(2+) membrane exchanger, is highly expressed in astrocytes, both in vitro and in vivo, in response to glutamate-induced excitotoxicity. Hence, the results of this analysis present a broad view of the expression profile elicited by MSG neonatal treatment, and lead us to suggest the possible molecular pathways of action and reaction involved under this experimental model of excitotoxicity.
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Affiliation(s)
- Daniel Ortuño-Sahagún
- Laboratorio de Desarrollo y Regeneración Neural, Instituto de Neurobiología, C.U.C.B.A, Universidad de Guadalajara, Guadalajara, Jalisco, México
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27
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Mosley CA, Acker TM, Hansen KB, Mullasseril P, Andersen KT, Le P, Vellano KM, Bräuner-Osborne H, Liotta DC, Traynelis SF. Quinazolin-4-one derivatives: A novel class of noncompetitive NR2C/D subunit-selective N-methyl-D-aspartate receptor antagonists. J Med Chem 2010; 53:5476-90. [PMID: 20684595 DOI: 10.1021/jm100027p] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We describe a new class of subunit-selective antagonists of N-methyl D-aspartate (NMDA)-selective ionotropic glutamate receptors that contain the (E)-3-phenyl-2-styrylquinazolin-4(3H)-one backbone. The inhibition of recombinant NMDA receptor function induced by these quinazolin-4-one derivatives is noncompetitive and voltage-independent, suggesting that this family of compounds does not exert action on the agonist binding site of the receptor or block the channel pore. The compounds described here resemble CP-465,022 ((S)-3-(2-chlorophenyl)-2-[2-(6-diethylaminomethyl-pyridin-2-yl)-vinyl]-6-fluoro-3H-quinazolin-4-one), a noncompetitive antagonist of AMPA-selective glutamate receptors. However, modification of ring substituents resulted in analogues with greater than 100-fold selectivity for recombinant NMDA receptors over AMPA and kainate receptors. Furthermore, within this series of compounds, analogues were identified with 50-fold selectivity for recombinant NR2C/D-containing receptors over NR2A/B containing receptors. These compounds represent a new class of noncompetitive subunit-selective NMDA receptor antagonists.
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Affiliation(s)
- Cara A Mosley
- Department of Chemistry, Emory University, Atlanta, Georgia 30033, USA
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Fidzinski P, Wawra M, Dugladze T, Gloveli T, Heinemann U, Behr J. Low-frequency stimulation of the temporoammonic pathway induces heterosynaptic disinhibition in the subiculum. Hippocampus 2010; 21:733-43. [DOI: 10.1002/hipo.20791] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/03/2010] [Indexed: 11/12/2022]
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Hori N, Kadota MT, Watanabe M, Ito Y, Akaike N, Carpenter DO. Neurotoxic effects of methamphetamine on rat hippocampus pyramidal neurons. Cell Mol Neurobiol 2010; 30:849-56. [PMID: 20232135 DOI: 10.1007/s10571-010-9512-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2010] [Accepted: 03/02/2010] [Indexed: 11/24/2022]
Abstract
Methamphetamine (MAP) is known to alter behavior and cause deficits in learning and memory. While the major site of action of MAP is on mesolimbic dopaminergic pathways, the effects on learning and memory raise the possibility of important actions in the hippocampus. We have studied electrophysiologic and morphologic effects of MAP in the CA1 region of hippocampus from young male rats chronically exposed to MAP, male rats exposed during gestation only and the effects of bath perfusion of MAP onto brain slices from control rats. Pyramidal neurons in brain slices from chronically exposed rats had reduced membrane potential and membrane resistance. Long-term potentiation (LTP) was reduced as compared to control, but when MAP was acutely perfused over control slices the amplitude of LTP was increased. LTP in young adult animals that had been gestationally exposed to MAP showed reduced LTP as compared to controls. Morphologically CA1 pyramidal neurons in chronically exposed animals showed a high prevalence of extensive blebbing of dendrites. We conclude that the NMDA receptor and the process of LTP are also targets of MAP dysfunction, at least in the hippocampus.
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Affiliation(s)
- N Hori
- Division of Life Science, University of Texas at San Antonio, 6900 North Loop 1604, West San Antonio, TX 78249-066, USA
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Sedaghati M, Vousooghi N, Goodarzi A, Yaghmaei P, Mokri A, Zarrindast MR. Expression of NR3B but not NR2D subunit of NMDA receptor in human blood lymphocytes can serve as a suitable peripheral marker for opioid addiction studies. Eur J Pharmacol 2010; 633:50-4. [PMID: 20153313 DOI: 10.1016/j.ejphar.2010.02.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2009] [Revised: 12/17/2009] [Accepted: 02/02/2010] [Indexed: 11/18/2022]
Abstract
Glutamate is critically involved in opioid addiction. It has been suggested that neurotransmitter receptors expression in peripheral blood lymphocytes may reflect brain status. In the present study, using Real-time PCR, the mRNA expression of NR2D and NR3B subunits of NMDA glutamate receptor has been investigated in peripheral blood lymphocytes of four groups each comprising of 25 male individuals: opioid addicts, methadone maintained patients, long-term abstinent former opioid addicts, and non-addicted control subjects. We found that NR2D subunit mRNA expression was not changed in all three test groups in comparison to control subjects. However, the NR3B mRNA expression was significantly up-regulated by the factors 9.11 (P<0.001), 10.07 (P<0.001) and 4.08 (P<0.05) in abstinent, addicted and methadone maintained subjects, respectively relative to control group. As a conclusion, our data indicate that the transcriptional level of the NR2D subunit of NMDA receptor is not regulated by chronic opioid addiction. However, it seems that the over-expression of NR3B subunit of NMDA receptor is a long lasting result of opioid abuse. In addition, considerable decrease in the up-regulated state of the NR3B subunit by methadone may represent another benefit of methadone therapy for opioid addicts and may serve as a suitable marker to evaluate the successfulness of therapy.
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Affiliation(s)
- Mahmoud Sedaghati
- Science and Research Branch of Islamic Azad University, Tehran, Iran; Sina Cellular and Molecular Research Center, Tehran, Iran
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31
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Rangel A, Madroñal N, Massó AGI, Gavín R, Llorens F, Sumoy L, Torres JM, Delgado-García JM, Río JAD. Regulation of GABA(A) and glutamate receptor expression, synaptic facilitation and long-term potentiation in the hippocampus of prion mutant mice. PLoS One 2009; 4:e7592. [PMID: 19855845 PMCID: PMC2763346 DOI: 10.1371/journal.pone.0007592] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2009] [Accepted: 09/30/2009] [Indexed: 11/18/2022] Open
Abstract
Background Prionopathies are characterized by spongiform brain degeneration, myoclonia, dementia, and periodic electroencephalographic (EEG) disturbances. The hallmark of prioniopathies is the presence of an abnormal conformational isoform (PrPsc) of the natural cellular prion protein (PrPc) encoded by the Prnp gene. Although several roles have been attributed to PrPc, its putative functions in neuronal excitability are unknown. Although early studies of the behavior of Prnp knockout mice described minor changes, later studies report altered behavior. To date, most functional PrPc studies on synaptic plasticity have been performed in vitro. To our knowledge, only one electrophysiological study has been performed in vivo in anesthetized mice, by Curtis and coworkers. They reported no significant differences in paired-pulse facilitation or LTP in the CA1 region after Schaffer collateral/commissural pathway stimulation. Methodology/Principal Findings Here we explore the role of PrPc expression in neurotransmission and neural excitability using wild-type, Prnp −/− and PrPc-overexpressing mice (Tg20 strain). By correlating histopathology with electrophysiology in living behaving mice, we demonstrate that both Prnp −/− mice but, more relevantly Tg20 mice show increased susceptibility to KA, leading to significant cell death in the hippocampus. This finding correlates with enhanced synaptic facilitation in paired-pulse experiments and hippocampal LTP in living behaving mutant mice. Gene expression profiling using Illumina™ microarrays and Ingenuity pathways analysis showed that 129 genes involved in canonical pathways such as Ubiquitination or Neurotransmission were co-regulated in Prnp −/− and Tg20 mice. Lastly, RT-qPCR of neurotransmission-related genes indicated that subunits of GABAA and AMPA-kainate receptors are co-regulated in both Prnp −/− and Tg20 mice. Conclusions/Significance Present results demonstrate that PrPc is necessary for the proper homeostatic functioning of hippocampal circuits, because of its relationships with GABAA and AMPA-Kainate neurotransmission. New PrPc functions have recently been described, which point to PrPc as a target for putative therapies in Alzheimer's disease. However, our results indicate that a “gain of function” strategy in Alzheimer's disease, or a “loss of function” in prionopathies, may impair PrPc function, with devastating effects. In conclusion, we believe that present data should be taken into account in the development of future therapies.
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Affiliation(s)
- Alejandra Rangel
- Molecular and Cellular Neurobiotechnology, Institute for Bioengineering of Catalonia, and Department of Cell Biology, University of Barcelona, Barcelona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Noelia Madroñal
- Division de Neurociencias. Universidad Pablo de Olavide, Sevilla, Spain
| | | | - Rosalina Gavín
- Molecular and Cellular Neurobiotechnology, Institute for Bioengineering of Catalonia, and Department of Cell Biology, University of Barcelona, Barcelona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Franc Llorens
- Molecular and Cellular Neurobiotechnology, Institute for Bioengineering of Catalonia, and Department of Cell Biology, University of Barcelona, Barcelona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Lauro Sumoy
- Institute of Predictive and Personalized Medicine of Cancer, Badalona, Spain
| | - Juan María Torres
- Centro de Investigación en Sanidad Animal (CISA), INIA, Valdeolmos, Madrid, Spain
| | | | - José Antonio Del Río
- Molecular and Cellular Neurobiotechnology, Institute for Bioengineering of Catalonia, and Department of Cell Biology, University of Barcelona, Barcelona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
- * E-mail: (JADR); (JMDG)
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Arrested maturation of excitatory synapses in autosomal dominant lateral temporal lobe epilepsy. Nat Med 2009; 15:1208-14. [PMID: 19701204 PMCID: PMC2759408 DOI: 10.1038/nm.2019] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2009] [Accepted: 07/28/2009] [Indexed: 02/08/2023]
Abstract
A subset of central glutamatergic synapses are coordinatelypruned and matured by unresolved mechanisms during early postnatal life. We report that human epilepsy gene LGI1, mutated in autosomal dominant lateral temporal lobe epilepsy (ADLTE), mediates this process in hippocampus. We introduced full-length genes encoding (1) ADLTE truncated mutant LGI1 (835delC) and (2) excess wild-type LGI1 proteins into transgenic mice. We discovered that the normal postnatal Kv1 channel-dependent down-regulation of presynaptic release probability and Src kinase-related decrease of postsynaptic NR2B/NR2A ratio were arrested by ADLTE mutant LGI1, and contrastingly, were magnified by excess wild-type LGI1. Concurrently, mutant LGI1 inhibited dendritic pruning and increased the spine density to markedly increase excitatory transmission. Inhibitory transmission, by contrast, was unaffected. Furthermore, mutant LGI1 promoted epileptiform discharge in vitro and kindling epileptogenesis in vivo with partial GABAA receptor blockade. Thus, LGI1 represents the first human gene mutated to promote epilepsy through impaired glutamatergic circuit maturation.
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Extrasynaptic NR2D-containing NMDARs are recruited to the synapse during LTP of NMDAR-EPSCs. J Neurosci 2008; 28:11685-94. [PMID: 18987204 DOI: 10.1523/jneurosci.3035-08.2008] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Long-term potentiation of NMDA-receptor-mediated synaptic transmission (NMDAR-LTP) is a little-understood form of plasticity. In the present study, we investigated whether NMDAR-LTP in the dentate gyrus involves recruitment of extrasynaptic NMDARs, because NMDARs are expressed both synaptically and extrasynaptically with evidence for subtype differences at different locations. We show that before induction of NMDAR-LTP, pharmacological inhibition of glutamate transporters resulted in glutamate spillover from the synapse and activation of extrasynaptic NMDARs. After the induction of NMDAR-LTP, such activation of extrasynaptic NMDARs was absent. Activation of extrasynaptic NMDARs after glutamate uptake inhibition also occurred when synaptic NMDARs were inhibited with MK801 [(+)-5-methyl-10,11-dihydro-5H-dibenzo [a,d] cyclohepten-5,10-imine maleate], and this extrasynaptically mediated NMDAR-EPSC was strongly reduced by prior induction of NMDAR-LTP. The extrasynaptic NMDARs were shown to be NR2D-containing, because the activation of extrasynaptic NMDARs by glutamate spillover was prevented by the NR2D-selective antagonists PPDA [(2R*,3S*)-1-(phenanthrenyl-2-carbonyl)piperazine-2,3-dicarboxylic acid] and UBP141. Further studies using selective antagonists for NR2A- and NR2B-containing NMDARs demonstrated that synaptic NMDARs are predominantly NR2A-containing and NR2B-containing receptors, whereas the extrasynaptic NMDARs are complex multimeric receptors with NR2A, NR2B, or NR2D subunits. Our results show that LTP of NMDAR-EPSCs involves movement of NMDARs from an extrasynaptic to a synaptic location and suggest a novel physiological role for extrasynaptic NMDARs.
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Suzuki T, Kodama S, Hoshino C, Izumi T, Miyakawa H. A plateau potential mediated by the activation of extrasynaptic NMDA receptors in rat hippocampal CA1 pyramidal neurons. Eur J Neurosci 2008; 28:521-34. [DOI: 10.1111/j.1460-9568.2008.06324.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Anatomical localization and expression pattern for the NMDA-2D receptor subunit in a rat model of neuropathic pain. Neuroscience 2008; 155:492-502. [PMID: 18585442 DOI: 10.1016/j.neuroscience.2008.05.041] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2008] [Revised: 05/16/2008] [Accepted: 05/17/2008] [Indexed: 11/23/2022]
Abstract
The N-methyl-d-aspartate receptor (NMDAR) has been implicated in the etiology of chronic pain. In this regard, this study sought to characterize the localization and expression pattern for the NMDAR-2D subunit in a rat model of neuropathic pain. To this end, one group of rats, 3 weeks post-dorsal root rhizotomy (DRR) and a second group, 3 weeks post-spinal nerve ligation (SNL) and sham surgery, were generated. Dorsal root ganglia (DRG) and/or lumbar spinal cord were excised from DRR, naïve, SNL and sham rats. Both immunohistochemical and real-time PCR analysis confirmed discrete NMDAR-2D subunit expression within the DRG and dorsal horn. However, no overt differences in staining intensity or expression were noted between DRG and spinal cord sections obtained from the different surgical groups. Results also demonstrated that the NMDAR-2D subunit was present within Neu N+ cells in the spinal cord and DRG, but excluded from cells labeled with the astrocytic marker, GFAP, and the microglial maker, OX-42. Lastly, the NMDAR-2D subunit was not co-expressed within neurokinin-1 (NK-1)+ or neurofilament-52 (N-52)+ neurons, but the antibody did co-label a number of isolectin B4+ (IB4) DRG cells. Together, these findings seem to suggest that the NMDAR-2D receptor subunit is present within the cell body region of a population of small diameter sensory afferents and post-synaptically within second order dorsal horn neurons. Although these data suggest that the NMDAR-2D subunit is well poised anatomically to modulate pain neurotransmission, the expression pattern for this subunit is not altered in rats demonstrating the presence of neuropathic-like pain behavior.
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Boulland JL, Jenstad M, Boekel AJ, Wouterlood FG, Edwards RH, Storm-Mathisen J, Chaudhry FA. Vesicular glutamate and GABA transporters sort to distinct sets of vesicles in a population of presynaptic terminals. ACTA ACUST UNITED AC 2008; 19:241-8. [PMID: 18502731 DOI: 10.1093/cercor/bhn077] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Vesicular glutamate transporters (VGLUTs) 1 and 2 are expressed by neurons generally accepted to release glutamate as a neurotransmitter, whereas VGLUT3 appears in populations usually associated with a different classical transmitter. We now demonstrate VGLUT2 as well as the vesicular GABA transporter (VGAT) in a subset of presynaptic terminals in the dentate gyrus of the rat hippocampal formation. The terminals are distributed in a characteristic band overlapping with the outer part of the granule cell layer and the inner zone of the molecular layer. Within the terminals, which make asymmetric as well as symmetric synapses onto the somatodendritic compartment of the dentate granule cells, the 2 transporters localize to distinct populations of synaptic vesicles. Moreover, the axons forming these terminals originate in the supramammillary nucleus (SuM). Our data reconcile previous apparently conflicting reports on the physiology of the dentate afferents from SuM and demonstrate that both glutamate and GABA may be released from a single nerve terminal.
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Khosravani H, Zhang Y, Tsutsui S, Hameed S, Altier C, Hamid J, Chen L, Villemaire M, Ali Z, Jirik FR, Zamponi GW. Prion protein attenuates excitotoxicity by inhibiting NMDA receptors. ACTA ACUST UNITED AC 2008; 181:551-65. [PMID: 18443219 PMCID: PMC2364707 DOI: 10.1083/jcb.200711002] [Citation(s) in RCA: 192] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
It is well established that misfolded forms of cellular prion protein (PrP [PrPC]) are crucial in the genesis and progression of transmissible spongiform encephalitis, whereas the function of native PrPC remains incompletely understood. To determine the physiological role of PrPC, we examine the neurophysiological properties of hippocampal neurons isolated from PrP-null mice. We show that PrP-null mouse neurons exhibit enhanced and drastically prolonged N-methyl-d-aspartate (NMDA)–evoked currents as a result of a functional upregulation of NMDA receptors (NMDARs) containing NR2D subunits. These effects are phenocopied by RNA interference and are rescued upon the overexpression of exogenous PrPC. The enhanced NMDAR activity results in an increase in neuronal excitability as well as enhanced glutamate excitotoxicity both in vitro and in vivo. Thus, native PrPC mediates an important neuroprotective role by virtue of its ability to inhibit NR2D subunits.
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Affiliation(s)
- Houman Khosravani
- Department of Physiology and Biophysics, Hotchkiss Brain Institute, University of Calgary, Calgary T2N4N1, Canada
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Imamura Y, Ma CL, Pabba M, Bergeron R. Sustained saturating level of glycine induces changes in NR2B-containing-NMDA receptor localization in the CA1 region of the hippocampus. J Neurochem 2008; 105:2454-65. [DOI: 10.1111/j.1471-4159.2008.05324.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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40
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Dietz RM, Kiedrowski L, Shuttleworth CW. Contribution of Na(+)/Ca(2+) exchange to excessive Ca(2+) loading in dendrites and somata of CA1 neurons in acute slice. Hippocampus 2008; 17:1049-59. [PMID: 17598158 DOI: 10.1002/hipo.20336] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Multiple Ca(2+) entry routes have been implicated in excitotoxic Ca(2+) loading in neurons and reverse-operation of sodium-calcium exchangers (NCX) has been shown to contribute under conditions where intracellular Na(+) levels are enhanced. We have investigated effects of KB-R7943, an inhibitor of reverse-operation NCX activity, on Ca(2+) elevations in single CA1 neurons in acute hippocampal slices. KB-R7943 had no significant effect on input resistance, action potential waveform, or action potential frequency adaptation, but reduced L-type Ca(2+) entry in somata. Nimodipine was therefore included in subsequent experiments to prevent complication from effects of L-type influx on evaluation of NCX activity. NMDA produced transient primary Ca(2+) increases, followed by propagating secondary Ca(2+) increases that initiated in apical dendrites. KB-R7943 had no significant effect on primary or secondary Ca(2+) increases generated by NMDA. The Na(+)/K(+) ATPase inhibitor ouabain (30 microM) produced degenerative Ca(2+) overload that was initiated in basal dendrites. KB-R7943 significantly reduced initial Ca(2+) increases and delayed the propagation of degenerative Ca(2+) loads triggered by ouabain, raising the possibility that excessive intracellular Na(+) loading can trigger reverse-operation NCX activity. A combination of NMDA and ouabain produced more rapid Ca(2+) overload, that was contributed to by NCX activity. These results suggest that degenerative Ca(2+) signaling can be triggered by NMDA in dendrites, before intracellular Na(+) levels become sufficient to reverse NCX activity. However, since Na(+)/K(+) ATPase inhibition does appear to produce significant reverse-operation NCX activity, this additional Ca(2+) influx pathway may operate in ATP-deprived CA1 neurons and play a role in ischemic neurodegeneration.
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Affiliation(s)
- Robert M Dietz
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, New Mexico, USA
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Bloomfield C, O'Donnell P, French SJ, Totterdell S. Cholinergic neurons of the adult rat striatum are immunoreactive for glutamatergic N-methyl-d-aspartate 2D but not N-methyl-d-aspartate 2C receptor subunits. Neuroscience 2007; 150:639-46. [PMID: 17961930 DOI: 10.1016/j.neuroscience.2007.09.035] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2007] [Revised: 09/11/2007] [Accepted: 09/18/2007] [Indexed: 10/22/2022]
Abstract
Cholinergic neurons of the striatum play a crucial role in controlling output from this region. Their firing is under the control of a relatively limited glutamatergic input, deriving principally from the thalamus. Glutamate transmission is effected via three major subtypes of receptors, including those with affinity for N-methyl-d-aspartate (NMDA) and the properties of individual receptors reflect their precise subunit composition. We examined the distribution of NMDA2C and NMDA2D subunits in the rat striatum using immunocytochemistry and show that a population of large neurons is strongly immunoreactive for NMDA2D subunits. From their morphology and ultrastructure, these neurons were presumed to be cholinergic and this was confirmed with double immunofluorescence. We also show that NMDA2C is present in a small number of septal and olfactory cortical neurons but absent from the striatum. Receptors that include NMDA2D subunits are relatively insensitive to magnesium ion block making neurons more likely to fire at more negative membrane potentials. Their localization to cholinergic neurons may enable very precise regulation of firing of these neurons by relatively small glutamatergic inputs.
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Affiliation(s)
- C Bloomfield
- Department of Pharmacology, Oxford University, Mansfield Road, Oxford, OX1 3QT UK
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MacDonald JF, Jackson MF, Beazely MA. G protein-coupled receptors control NMDARs and metaplasticity in the hippocampus. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1768:941-51. [PMID: 17261268 DOI: 10.1016/j.bbamem.2006.12.006] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2006] [Revised: 12/06/2006] [Accepted: 12/09/2006] [Indexed: 11/20/2022]
Abstract
Long-term potentiation (LTP) and long-term depression (LTD) are the major forms of functional synaptic plasticity observed at CA1 synapses of the hippocampus. The balance between LTP and LTD or "metaplasticity" is controlled by G-protein coupled receptors (GPCRs) whose signal pathways target the N-methyl-D-asparate (NMDA) subtype of excitatory glutamate receptor. We discuss the protein kinase signal cascades stimulated by Galphaq and Galphas coupled GPCRs and describe how control of NMDAR activity shifts the threshold for the induction of LTP.
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Affiliation(s)
- John F MacDonald
- Department of Physiology, University of Toronto, Toronto, ON, Canada.
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Wang D, Noda Y, Tsunekawa H, Zhou Y, Miyazaki M, Senzaki K, Nabeshima T. Behavioural and neurochemical features of olfactory bulbectomized rats resembling depression with comorbid anxiety. Behav Brain Res 2007; 178:262-73. [PMID: 17261334 DOI: 10.1016/j.bbr.2007.01.003] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2006] [Revised: 12/22/2006] [Accepted: 01/02/2007] [Indexed: 11/16/2022]
Abstract
In order to probe the nature and validity of olfactory bulbectomized (OB) rats as a model of depression, we reevaluated their behavioural and neurochemical deficits in relation to the symptoms and neurochemical abnormalities of depression using our protocols, which distinguish anhedonia-resembling behaviour in sexual behavioural test, the hippocampus (Hip)-dependent long-term memory and anxiety-resembling behaviour specially. Besides exploratory hyperactivity in response to a novel environmental stress resembling the psychomotor agitation, OB rats showed a decrease of libido, and a deficit of long-term explicit memory, resembling loss of interest and cognitive deficits in depressive patients, respectively. OB rats also exhibited the anxiety symptom-resembling behaviour in social interaction and plus-maze tests. In the OB rats, we found degenerated neurons in the piriform cortex, decreased protein expression of NMDA receptor subunit 1 (NR1), but not NR2A or NR2B, in the prefrontal cortex (PFC), Hip and amygdala (Amg), and decreased phosphorylation of cAMP-response element-binding protein (CREB) in the PFC and Hip, but not Amg. The behavioural and neurochemical abnormalities in OB rats, except for the performance in the plus-maze task and neuronal degeneration, were significantly attenuated by repeated treatment with desipramine (10 mg/kg), a typical antidepressant. The present study indicated that OB rats may be a model of depression with comorbid anxiety, characterized by agitation, sexual and cognitive dysfunction, neuronal degeneration, decreased protein expression of NR1, and decreased phosphorylation of CREB.
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Affiliation(s)
- Dayong Wang
- Department of Neuropsychopharmacology and Hospital Pharmacy, Nagoya University Graduate School of Medicine, Nagoya 466-8560, Japan
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Berberich S, Jensen V, Hvalby Ø, Seeburg PH, Köhr G. The role of NMDAR subtypes and charge transfer during hippocampal LTP induction. Neuropharmacology 2007; 52:77-86. [PMID: 16901514 DOI: 10.1016/j.neuropharm.2006.07.016] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2006] [Revised: 07/10/2006] [Accepted: 07/12/2006] [Indexed: 11/16/2022]
Abstract
Activation of NMDA receptors (NMDARs) is a requirement for persistent synaptic alterations, such as long-term potentiation of synaptic transmission (LTP). NMDARs are composed of NR1 and NR2 subunits, and NR2 subunit-dependent gating properties of NMDAR subtypes cause dramatic differences in the timing of charge transfer. These postsynaptic temporal profiles are further influenced by the frequency of synaptic activation. Here, we investigated in the CA1 region of hippocampal slices from P28 mice, whether particular NMDAR subtypes are recruited based on NR2 subunit-specific gating following different induction protocols. For high frequency afferent stimulation (HFS), we found that genetic impairment of NR2A or pharmacological block of NR2A- or NR2B-type NMDARs can reduce field LTP. In contrast, when pairing low frequency synaptic stimulation with postsynaptic depolarization (LFS pairing) in single CA1 neurons, pharmacological antagonism of either subtype modestly reduced the charge transfer during LFS pairing without reducing the LTP magnitude. These results indicate that HFS-triggered LTP is induced by more than one NMDAR subtype, whereas a single subtype is sufficient during LFS pairing. Analysis of charge transfer during LFS pairing in 13 different conditions revealed a threshold for LTP induction, which was independent of the NR2 antagonist tested. Thus, at least for LFS pairing, the amount of charge transfer, and thus Ca2+ influx, during LTP induction is a factor more critical than the participation of a particular NMDAR subtype.
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Affiliation(s)
- Sven Berberich
- Department of Molecular Neurobiology, Max-Planck-Institute for Medical Research, Jahnstrasse 29, D-69120 Heidelberg, Germany
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Le Meur K, Galante M, Angulo MC, Audinat E. Tonic activation of NMDA receptors by ambient glutamate of non-synaptic origin in the rat hippocampus. J Physiol 2006; 580:373-83. [PMID: 17185337 PMCID: PMC2075557 DOI: 10.1113/jphysiol.2006.123570] [Citation(s) in RCA: 172] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
In several neuronal types of the CNS, glutamate and GABA receptors mediate a persistent current which reflects the presence of a low concentration of transmitters in the extracellular space. Here, we further characterize the tonic current mediated by ambient glutamate in rat hippocampal slices. A tonic current of small amplitude (53.99 +/- 6.48 pA at +40 mV) with the voltage dependency and the pharmacology of NMDA receptors (NMDARs) was detected in virtually all pyramidal cells of the CA1 and subiculum areas. Manipulations aiming at increasing D-serine or glycine extracellular concentrations failed to modify this current indicating that the glycine binding sites of the NMDARs mediating the tonic current were saturated. In contrast, non-transportable inhibitors of glutamate transporters increased the amplitude of this tonic current, indicating that the extracellular concentration of glutamate primarily regulates its magnitude. Neither AMPA/kainate receptors nor metabotropic glutamate receptors contributed significantly to this tonic excitation of pyramidal neurons. In the presence of glutamate transporter inhibitors, however, a significant proportion of the tonic conductance was mediated by AMPA receptors. The tonic current was unaffected when inhibiting vesicular release of transmitters from neurons but was increased upon inhibition of the enzyme converting glutamate in glutamine in glial cells. These observations indicate that ambient glutamate is mainly of glial origin. Finally, experiments with the use-dependent antagonist MK801 indicated that NMDARs mediating the tonic conductance are probably extra-synaptic NMDARs.
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Affiliation(s)
- Karim Le Meur
- Inserm U603, Université Paris Descartes, 45 rue des Saints Pères, 75006 Paris, France
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Abstract
Voltage-dependent channel block by external Mg2+ (Mg2+(o)) of NMDA receptors is an essential determinant of synaptic function. The resulting Mg2+(o) inhibition of NMDA responses depends strongly on receptor subunit composition: NR1/2A and NR1/2B receptors are more strongly inhibited by Mg2+(o) than are NR1/2C or NR1/2D receptors. Previous work showed that permeant ions have profound effects on Mg2+(o) block of NMDA receptors composed of NR1, NR2A, and NR2B subunits. Whether permeant ions affect Mg2+(o) inhibition of NR1/2C or NR1/2D receptors is unknown. We investigated the effects of permeant ions on Mg2+(o) block of NR1/2D receptors by integrating results from whole-cell recordings, single-channel recordings, and kinetic modeling. Lowering internal [Cs+] caused a voltage-dependent decrease in the Mg2+(o) IC50 and in the apparent Mg2+(o) unblocking rate, and increase in the apparent Mg2+(o) blocking rate (k(+,app)) of NR1/2D receptors. Lowering external [Na+] caused modest voltage-dependent changes in the Mg2+(o) IC50 and k(+,app). These data can be explained by a kinetic model in which occupation of either of two external permeant ion binding sites prevents Mg2+(o) entry into the channel. Occupation of an internal permeant ion binding site prevents Mg2+(o) permeation and accelerates Mg2+(o) unblock to the external solution. We conclude that variations in permeant ion site properties shape the NR2 subunit dependence of Mg2+(o) block. Furthermore, the external channel entrance varies little among NMDA receptor subtypes. Differences in the Mg2+(o) blocking site, and particularly in the selectivity filter and internal channel entrance, are principally responsible for the subunit dependence of Mg2+(o) block.
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Affiliation(s)
- Anqi Qian
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania 15260
| | - Jon W. Johnson
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania 15260
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Adams CE, Yonchek JC, Stitzel JA. Development of hippocampal alpha7 nicotinic receptors in C3H and DBA/2 congenic mice. Brain Res 2006; 1122:27-35. [PMID: 17010324 DOI: 10.1016/j.brainres.2006.08.113] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2006] [Revised: 08/24/2006] [Accepted: 08/31/2006] [Indexed: 02/04/2023]
Abstract
The time course and pattern of development of hippocampal alpha7 nicotinic acetylcholine receptors is discernibly different in C3H and DBA/2 mice. In C3H mice, the alpha7 receptor is initially expressed on embryonic day 13, exhibits an increase in density in area CA1 perinatally and is characterized by a dense, diffuse band of alpha-bungarotoxin binding at the CA3/CA1 border in the adult. In contrast, the alpha7 receptor is initially expressed on embryonic day 16 in DBA/2 mice, does not exhibit a transient perinatal increase in binding density in area CA1 and is characterized by alpha-bungarotoxin binding to numerous Nissl-stained structures in CA1 lacunosum/moleculare in the adult. Currently, it is not known whether these developmental differences occur solely as a result of the different alleles of the alpha7 receptor gene (Chrna7) expressed by the two strains or whether strain-specific background factors also play a role. The present study qualitatively examines this question by comparing alpha7 receptor development in congenic mice in which the DBA/2 allele of Chrna7 has been introgressed onto a C3H genetic background and, conversely, the C3H allele of Chrna7 has been introgressed onto a DBA/2 genetic background. The data suggest that hippocampal alpha7 receptor development is controlled predominantly by a region of mouse chromosome 7 that contains the strain-specific Chrna7 allele.
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Affiliation(s)
- Catherine E Adams
- Department of Psychiatry, Veterans Affairs Medical Center, Denver, CO 80220, and University of Colorado at Denver and Health Sciences Center, Aurora, CO 80045, USA.
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48
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Payne HL, Donoghue PS, Connelly WMK, Hinterreiter S, Tiwari P, Ives JH, Hann V, Sieghart W, Lees G, Thompson CL. Aberrant GABA(A) receptor expression in the dentate gyrus of the epileptic mutant mouse stargazer. J Neurosci 2006; 26:8600-8. [PMID: 16914686 PMCID: PMC2974089 DOI: 10.1523/jneurosci.1088-06.2006] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Stargazer (stg) mutant mice fail to express stargazin [transmembrane AMPA receptor regulatory protein gamma2 (TARPgamma2)] and consequently experience absence seizure-like thalamocortical spike-wave discharges that pervade the hippocampal formation via the dentate gyrus (DG). As in other seizure models, the dentate granule cells of stg develop elaborate reentrant axon collaterals and transiently overexpress brain-derived neurotrophic factor. We investigated whether GABAergic parameters were affected by the stg mutation in this brain region. GABA(A) receptor (GABAR) alpha4 and beta3 subunits were consistently upregulated, GABAR delta expression appeared to be variably reduced, whereas GABAR alpha1, beta2, and gamma2 subunits and the GABAR synaptic anchoring protein gephyrin were essentially unaffected. We established that the alpha4 betagamma2 subunit-containing, flunitrazepam-insensitive subtype of GABARs, not normally a significant GABAR in DG neurons, was strongly upregulated in stg DG, apparently arising at the expense of extrasynaptic alpha4 betadelta-containing receptors. This change was associated with a reduction in neurosteroid-sensitive GABAR-mediated tonic current. This switch in GABAR subtypes was not reciprocated in the tottering mouse model of absence epilepsy implicating a unique, intrinsic adaptation of GABAergic networks in stg. Contrary to previous reports that suggested that TARPgamma2 is expressed in the dentate, we find that TARPgamma2 was neither detected in stg nor control DG. We report that TARPgamma8 is the principal TARP isoform found in the DG and that its expression is compromised by the stargazer mutation. These effects on GABAergic parameters and TARPgamma8 expression are likely to arise as a consequence of failed expression of TARPgamma2 elsewhere in the brain, resulting in hyperexcitable inputs to the dentate.
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Suárez LM, Solís JM. Taurine potentiates presynaptic NMDA receptors in hippocampal Schaffer collateral axons. Eur J Neurosci 2006; 24:405-18. [PMID: 16836643 DOI: 10.1111/j.1460-9568.2006.04911.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
We have previously shown that activation of presynaptic N-methyl-d-aspartate (NMDA) receptors (NMDAR) enhances the amplitude of the presynaptic fibre volley (FV) evoked in Schaffer collateral axons of rat hippocampal slices, by a mechanism independent of extracellular Ca(2+). Here we compared the pharmacological characteristics of presynaptic NMDARs affecting axon excitability (activated by 10-300 microM NMDA for 10 min), with those mediating field excitatory postsynaptic potentials (NMDA-fEPSP). We found that NMDA-induced potentiation was completely inhibited by NVP-AAM077, an antagonist of NR2A-containing NMDAR, but not by ifenprodil, an NR2B-selective antagonist. The inhibitor of the glycine-binding site in NMDARs, 7-clorokynurenic acid (7-CK), was more potent against NMDA-fEPSP (IC(50) = 6.3 +/- 1.3 microM) than against the NMDA-induced FV potentiation (IC(50) = 26.5 +/- 1.3 microM). Moreover, both post- and presynaptic NMDAR-mediated phenomena were enhanced by glycine and d-serine, but taurine, an endogenous analogue of glycine, only enhanced the latter (EC(50) = 19 microM). Taurine was able to block the inhibitory effect of low doses of 7-CK on NMDA-induced FV potentiation, while glycine and d-serine only reduced the effects of higher concentrations of this drug. Surprisingly, the enhancing effect of taurine on NMDA-induced FV potentiation was blocked when it was co-applied with glycine. Furthermore, the glutamate released synaptically with a train of stimuli also increased FV amplitude by a mechanism dependent on NMDARs; this was potentiated by taurine but not by co-application of taurine and glycine. These results reveal that presynaptic NMDARs have unique properties that mediate the facilitation of axon excitability.
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Affiliation(s)
- Luz M Suárez
- Servicio de Neurobiología-Investigación, Hospital Ramón y Cajal, Madrid 28034, Spain
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Mameli M, Carta M, Partridge LD, Valenzuela CF. Neurosteroid-induced plasticity of immature synapses via retrograde modulation of presynaptic NMDA receptors. J Neurosci 2006; 25:2285-94. [PMID: 15745954 PMCID: PMC6726098 DOI: 10.1523/jneurosci.3877-04.2005] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Neurosteroids are produced de novo in neuronal and glial cells, which begin to express steroidogenic enzymes early in development. Studies suggest that neurosteroids may play important roles in neuronal circuit maturation via autocrine and/or paracrine actions. However, the mechanism of action of these agents is not fully understood. We report here that the excitatory neurosteroid pregnenolone sulfate induces a long-lasting strengthening of AMPA receptor-mediated synaptic transmission in rat hippocampal neurons during a restricted developmental period. Using the acute hippocampal slice preparation and patch-clamp electrophysiological techniques, we found that pregnenolone sulfate increases the frequency of AMPA-mediated miniature excitatory postsynaptic currents in CA1 pyramidal neurons. This effect could not be observed in slices from rats older than postnatal day 5. The mechanism of action of pregnenolone sulfate involved a short-term increase in the probability of glutamate release, and this effect is likely mediated by presynaptic NMDA receptors containing the NR2D subunit, which is transiently expressed in the hippocampus. The increase in glutamate release triggered a long-term enhancement of AMPA receptor function that requires activation of postsynaptic NMDA receptors containing NR2B subunits. Importantly, synaptic strengthening could also be triggered by postsynaptic neuron depolarization, and an anti-pregnenolone sulfate antibody scavenger blocked this effect. This finding indicates that a pregnenolone sulfate-like neurosteroid is a previously unrecognized retrograde messenger that is released in an activity-dependent manner during development.
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Affiliation(s)
- Manuel Mameli
- Department of Neurosciences, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87131, USA
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