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Niu M, Yang X, Li Y, Sun Y, Wang L, Ha J, Xie Y, Gao Z, Tian C, Wang L, Sun Y. Progresses in GluN2A-containing NMDA Receptors and their Selective Regulators. Cell Mol Neurobiol 2023; 43:139-153. [PMID: 34978648 DOI: 10.1007/s10571-021-01185-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 12/18/2021] [Indexed: 01/07/2023]
Abstract
NMDA receptors play an important physiological role in regulating synaptic plasticity, learning and memory. GluN2A subunits are the most abundant functional subunits of NMDA receptors expressed in mature brain, and their dysfunction is related to various neurological diseases. According to subunit composition, GluN2A-containing NMDA receptors can be divided into two types: diheteromeric and triheteromeric receptors. In this review, the expression, functional and pharmacological properties of different kinds of GluN2A-containing NMDA receptors as well as selective GluN2A regulators were described to further understand this type of NMDA receptors.
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Affiliation(s)
- Menghan Niu
- Department of Pharmacy, Hebei University of Science and Technology, Yuhua East Road 70, Shijiazhuang, 050018, Hebei, China
| | - Xin Yang
- Department of Pharmaceutical Engineering, Hebei Chemical & Pharmaceutical College, Fangxing Road 88, Shijiazhuang, 050026, Hebei, China.,Hebei Technological Innovation Center of Chiral Medicine, Shijiazhuang, China
| | - Yuanyuan Li
- Department of Pharmacy, Hebei University of Science and Technology, Yuhua East Road 70, Shijiazhuang, 050018, Hebei, China
| | - Yanping Sun
- Department of Pharmacy, Hebei University of Science and Technology, Yuhua East Road 70, Shijiazhuang, 050018, Hebei, China.,Hebei Research Center of Pharmaceutical and Chemical Engineering, Hebei University of Science and Technology, Shijiazhuang, China.,State Key Laboratory Breeding Base-Hebei Province Key Laboratory of Molecular Chemistry for Drug, Shijiazhuang, China
| | - Long Wang
- Department of Family and Consumer Sciences, California State University, Long Beach, USA
| | - Jing Ha
- Department of Pharmacy, Hebei University of Science and Technology, Yuhua East Road 70, Shijiazhuang, 050018, Hebei, China
| | - Yinghua Xie
- Department of Pharmacy, Hebei University of Science and Technology, Yuhua East Road 70, Shijiazhuang, 050018, Hebei, China
| | - Zibin Gao
- Department of Pharmacy, Hebei University of Science and Technology, Yuhua East Road 70, Shijiazhuang, 050018, Hebei, China.,Hebei Research Center of Pharmaceutical and Chemical Engineering, Hebei University of Science and Technology, Shijiazhuang, China.,State Key Laboratory Breeding Base-Hebei Province Key Laboratory of Molecular Chemistry for Drug, Shijiazhuang, China
| | - Changzheng Tian
- Department of Anesthesiology, The First Hospital of Hebei Medical University, Donggang Road 89, Shijiazhuang, 050000, Hebei, China.
| | - Le Wang
- Department of Pharmaceutical Engineering, Hebei Chemical & Pharmaceutical College, Fangxing Road 88, Shijiazhuang, 050026, Hebei, China. .,Hebei Technological Innovation Center of Chiral Medicine, Shijiazhuang, China.
| | - Yongjun Sun
- Department of Pharmacy, Hebei University of Science and Technology, Yuhua East Road 70, Shijiazhuang, 050018, Hebei, China. .,Hebei Research Center of Pharmaceutical and Chemical Engineering, Hebei University of Science and Technology, Shijiazhuang, China. .,State Key Laboratory Breeding Base-Hebei Province Key Laboratory of Molecular Chemistry for Drug, Shijiazhuang, China.
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2
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Xue M, Zhou SB, Liu RH, Chen QY, Zhuo M, Li XH. NMDA Receptor-Dependent Synaptic Depression in Potentiated Synapses of the Anterior Cingulate Cortex of adult Mice. Mol Pain 2021; 17:17448069211018045. [PMID: 34024172 PMCID: PMC8141994 DOI: 10.1177/17448069211018045] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Long-term potentiation (LTP) is an important molecular mechanism for chronic pain in the anterior cingulate cortex (ACC), a key cortical region for pain perception and emotional regulation. Inhibiting ACC LTP via various manipulations or pharmacological treatments blocks chronic pain. Long-term depression (LTD) is another form of synaptic plasticity in the ACC, which is also proved to be involved in the mechanisms of chronic pain. However, less is known about the interactive relationship between LTP and LTD in the ACC. Whether the synaptic depression could be induced after synaptic LTP in the ACC is not clear. In the present study, we used multi-channel field potential recording systems to study synaptic depression after LTP in the ACC of adult mice. We found that low frequency stimulus (LFS: 1 Hz, 15 min) inhibited theta burst stimulation (TBS)-induced LTP at 30 min after the induction of LTP. However, LFS failed to induce depression at 90 min after the induction of LTP. Furthermore, NMDA receptor antagonist AP-5 blocked the induction of synaptic depression after potentiation. The GluN2B-selective antagonist Ro25-6981 also inhibited the phenomenon in the ACC, while the GluN2A-selective antagonist NVP-AAM077 and the GluN2C/D-selective antagonist PPDA and UBP145 had no any significant effect. These results suggest that synaptic LTP can be depressed by LTD in a time dependent manner, and GluN2B-containing NMDA receptors play important roles in this form of synaptic depression.
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Affiliation(s)
- Man Xue
- Center for Neuron and Disease, Frontier Institutes of Science and Technology, Xi'an Jiaotong University, Xi'an, China.,Institute of Brain Research, Qingdao International Academician Park, Qingdao, China
| | - Si-Bo Zhou
- Center for Neuron and Disease, Frontier Institutes of Science and Technology, Xi'an Jiaotong University, Xi'an, China.,Institute of Brain Research, Qingdao International Academician Park, Qingdao, China
| | - Ren-Hao Liu
- Center for Neuron and Disease, Frontier Institutes of Science and Technology, Xi'an Jiaotong University, Xi'an, China.,Institute of Brain Research, Qingdao International Academician Park, Qingdao, China
| | - Qi-Yu Chen
- Center for Neuron and Disease, Frontier Institutes of Science and Technology, Xi'an Jiaotong University, Xi'an, China.,Institute of Brain Research, Qingdao International Academician Park, Qingdao, China
| | - Min Zhuo
- Center for Neuron and Disease, Frontier Institutes of Science and Technology, Xi'an Jiaotong University, Xi'an, China.,Institute of Brain Research, Qingdao International Academician Park, Qingdao, China.,Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Xu-Hui Li
- Center for Neuron and Disease, Frontier Institutes of Science and Technology, Xi'an Jiaotong University, Xi'an, China.,Institute of Brain Research, Qingdao International Academician Park, Qingdao, China.,Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
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3
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Karantysh GV, Fomenko MP, Menzheritskii AM, Prokof’ev VN, Ryzhak GA, Butenko EV. Effect of Pinealon on Learning and Expression of NMDA Receptor Subunit Genes in the Hippocampus of Rats with Experimental Diabetes. NEUROCHEM J+ 2020. [DOI: 10.1134/s181971242003006x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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4
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Cellular and Molecular Changes in Hippocampal Glutamate Signaling and Alterations in Learning, Attention, and Impulsivity Following Prenatal Nicotine Exposure. Mol Neurobiol 2020; 57:2002-2020. [PMID: 31916029 DOI: 10.1007/s12035-019-01854-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Accepted: 12/11/2019] [Indexed: 12/18/2022]
Abstract
Over 70 million European pregnant women are smokers during their child-bearing years. Consumption of tobacco-containing products during pregnancy is associated with several negative behavioral outcomes for the offspring, including a higher susceptibility for the development of attention-deficit/hyperactive disorder (ADHD). In efforts to minimize fetal exposure to tobacco smoke, many women around the world switch to nicotine replacement therapies (NRTs) during the gestational period; however, prenatal nicotine exposure (PNE) in any form has been associated with alterations in cognitive processes, including learning, memory, and attention. These processes are controlled by glutamatergic signaling of hippocampal pyramidal neurons within the CA1 region, suggesting actions of nicotine on glutamatergic transmission in this region if present prenatally. Accordingly, we aimed to investigate hippocampal glutamatergic function following PNE treatment in NMRI mice employing molecular, cellular electrophysiology, and pharmacological approaches, as well as to evaluate cognition in the rodent continuous performance task (rCPT), a recently developed mouse task allowing assessment of learning, attention, and impulsivity. PNE induced increases in the expression levels of mRNA coding for different glutamate receptors and subunits within the hippocampus. Functional alterations in AMPA and NMDA receptors on CA1 pyramidal neurons of PNE mice were suggestive of higher GluA2-lacking and lower GluN2A-containing receptors, respectively. Finally, PNE was associated with reduced learning, attention, and enhanced impulsivity in the rCPT. Alterations in glutamatergic functioning in CA1 neurons parallel changes seen in the spontaneously hypertensive rat ADHD model and likely contribute to the lower cognitive performance in the rCPT.
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Davis-Reyes BD, Campbell VM, Land MA, Chapman HL, Stafford SJ, Anastasio NC. Profile of cortical N-methyl-D-aspartate receptor subunit expression associates with inherent motor impulsivity in rats. Biochem Pharmacol 2019; 168:204-213. [PMID: 31295463 PMCID: PMC6733662 DOI: 10.1016/j.bcp.2019.07.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 07/07/2019] [Indexed: 01/01/2023]
Abstract
Impulsivity is a multifaceted behavioral manifestation with implications in several neuropsychiatric disorders. Glutamate neurotransmission through the N-methyl-D-aspartate receptors (NMDARs) in the medial prefrontal cortex (mPFC), an important brain region in decision-making and goal-directed behaviors, plays a key role in motor impulsivity. We discovered that inherent motor impulsivity predicted responsiveness to D-cycloserine (DCS), a partial NMDAR agonist, which prompted the hypothesis that inherent motor impulsivity is associated with the pattern of expression of cortical NMDAR subunits (GluN1, GluN2A, GluN2B), specifically the protein levels and synaptosomal trafficking of the NMDAR subunits. Outbred male Sprague-Dawley rats were identified as high (HI) or low (LI) impulsive using the one-choice serial reaction time task. Following phenotypic identification, mPFC synaptosomal protein was extracted from HI and LI rats to assess the expression pattern of the NMDAR subunits. Synaptosomal trafficking and stabilization for the GluN2 subunits were investigated by co-immunoprecipitation for postsynaptic density 95 (PSD95) and synapse associated protein 102 (SAP102). HI rats had lower mPFC GluN1 and GluN2A, but higher GluN2B and pGluN2B synaptosomal protein expression versus LI rats. Further, higher GluN2B:PSD95 and GluN2B:SAP102 protein:protein interactions were detected in HI versus LI rats. Thus, the mPFC NMDAR subunit expression pattern and/or synaptosomal trafficking associates with high inherent motor impulsivity. Increased understanding of the complex regulation of NMDAR balance within the mPFC as it relates to inherent motor impulsivity may lead to a better understanding of risk factors for impulse-control disorders.
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Affiliation(s)
- Brionna D Davis-Reyes
- Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, USA
| | - Veronica M Campbell
- Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, USA
| | - Michelle A Land
- Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, USA
| | - Holly L Chapman
- Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, USA
| | - Susan J Stafford
- Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, USA
| | - Noelle C Anastasio
- Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, USA.
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6
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The GluN2A Subunit Regulates Neuronal NMDA receptor-Induced Microglia-Neuron Physical Interactions. Sci Rep 2018; 8:828. [PMID: 29339791 PMCID: PMC5770428 DOI: 10.1038/s41598-018-19205-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 12/19/2017] [Indexed: 11/11/2022] Open
Abstract
Microglia are known to engage in physical interactions with neurons. However, our understanding of the detailed mechanistic regulation of microglia-neuron interactions is incomplete. Here, using high resolution two photon imaging, we investigated the regulation of NMDA receptor-induced microglia-neuron physical interactions. We found that the GluN2A inhibitor NVPAAM007, but not the GluN2B inhibitor ifenprodil, blocked the occurrence of these interactions. Consistent with the well-known developmental regulation of the GluN2A subunit, these interactions are absent in neonatal tissues. Furthermore, consistent with a preferential synaptic localization of GluN2A subunits, there is a differential sensitivity of their occurrence between denser (stratum radiatum) and less dense (stratum pyramidale) synaptic sub-regions of the CA1. Finally, consistent with differentially expressed GluN2A subunits in the CA1 and DG areas of the hippocampus, these interactions could not be elicited in the DG despite robust microglial chemotactic capabilities. Together, these results enhance our understanding of the mechanistic regulation of NMDA receptor-dependent microglia-neuronal physical interactions phenomena by the GluN2A subunit that may be relevant in the mammalian brain during heightened glutamatergic neurotransmission such as epilepsy and ischemic stroke.
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7
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Koga K, Li S, Zhuo M. Metabotropic Glutamate Receptor Dependent Cortical Plasticity in Chronic Pain. Curr Neuropharmacol 2017; 14:427-34. [PMID: 27296638 PMCID: PMC4983748 DOI: 10.2174/1570159x13666150425002304] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 04/09/2015] [Accepted: 04/22/2015] [Indexed: 11/22/2022] Open
Abstract
Many cortical areas play crucial roles in higher order brain functions such as pain and emotion-processing, decision-making, and cognition. Among them, anterior cingulate cortex (ACC) and insular cortex (IC) are two key areas. Glutamate mediates major excitatory transmission during long-term plasticity in both physiological and pathological conditions. Specifically related to nociceptive or pain behaviors, metabotropic glutamate subtype receptors (mGluRs) have been involved in different types of synaptic modulation and plasticity from periphery to the spinal cord. However, less is known about their functional roles in plasticity related to pain and its related behaviors within cortical regions. In this review, we first summarized previous studies of synaptic plasticity in both the ACC and IC, and discussed how mGluRs may be involved in both cortical long-term potentiation (LTP) and long-term depression (LTD)-especially in LTD. The activation of mGluRs contributes to the induction of LTD in both ACC and IC areas. The loss of LTD caused by peripheral amputation or nerve injury can be rescued by priming ACC or IC with activations of mGluR1 receptors. We also discussed the potential functional roles of mGluRs for pain-related behaviors. We propose that targeting mGluRs in the cortical areas including the ACC and IC may provide a new therapeutic strategy for the treatment of chronic pain, phantom pain or anxiety.
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Affiliation(s)
| | | | - Min Zhuo
- Department of Physiology, Faculty of Medicine, University of Toronto, Medical Science Building, Room #3342, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada.
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8
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Zhang WB, Ross PJ, Tu Y, Wang Y, Beggs S, Sengar AS, Ellis J, Salter MW. Fyn Kinase regulates GluN2B subunit-dominant NMDA receptors in human induced pluripotent stem cell-derived neurons. Sci Rep 2016; 6:23837. [PMID: 27040756 PMCID: PMC4819183 DOI: 10.1038/srep23837] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Accepted: 03/15/2016] [Indexed: 12/28/2022] Open
Abstract
NMDA receptor (NMDAR)-mediated fast excitatory neurotransmission is implicated in a broad range of physiological and pathological processes in the mammalian central nervous system. The function and regulation of NMDARs have been extensively studied in neurons from rodents and other non-human species, and in recombinant expression systems. Here, we investigated human NMDARs in situ by using neurons produced by directed differentiation of human induced pluripotent stem cells (iPSCs). The resultant cells showed electrophysiological characteristics demonstrating that they are bona fide neurons. In particular, human iPSC-derived neurons expressed functional ligand-gated ion channels, including NMDARs, AMPA receptors, GABAA receptors, as well as glycine receptors. Pharmacological and electrophysiological properties of NMDAR-mediated currents indicated that these were dominated by receptors containing GluN2B subunits. The NMDAR currents were suppressed by genistein, a broad-spectrum tyrosine kinase inhibitor. The NMDAR currents were also inhibited by a Fyn-interfering peptide, Fyn(39–57), but not a Src-interfering peptide, Src(40–58). Together, these findings are the first evidence that tyrosine phosphorylation regulates the function of NMDARs in human iPSC-derived neurons. Our findings provide a basis for utilizing human iPSC-derived neurons in screening for drugs targeting NMDARs in neurological disorders.
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Affiliation(s)
- Wen-Bo Zhang
- Program in Neurosciences &Mental Health, The Hospital for Sick Children, Toronto, ON, M5G 0A4, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - P Joel Ross
- Program in Developmental &Stem Cell Biology, The Hospital for Sick Children, Toronto, ON, M5G 0A4, Canada
| | - YuShan Tu
- Program in Neurosciences &Mental Health, The Hospital for Sick Children, Toronto, ON, M5G 0A4, Canada
| | - Yongqian Wang
- Program in Neurosciences &Mental Health, The Hospital for Sick Children, Toronto, ON, M5G 0A4, Canada
| | - Simon Beggs
- Program in Neurosciences &Mental Health, The Hospital for Sick Children, Toronto, ON, M5G 0A4, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Ameet S Sengar
- Program in Neurosciences &Mental Health, The Hospital for Sick Children, Toronto, ON, M5G 0A4, Canada
| | - James Ellis
- Program in Developmental &Stem Cell Biology, The Hospital for Sick Children, Toronto, ON, M5G 0A4, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Michael W Salter
- Program in Neurosciences &Mental Health, The Hospital for Sick Children, Toronto, ON, M5G 0A4, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada
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Ma SH, Zhuang QX, Shen WX, Peng YP, Qiu YH. Interleukin-6 reduces NMDAR-mediated cytosolic Ca²⁺ overload and neuronal death via JAK/CaN signaling. Cell Calcium 2015; 58:286-95. [PMID: 26104917 DOI: 10.1016/j.ceca.2015.06.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 04/30/2015] [Accepted: 06/10/2015] [Indexed: 11/30/2022]
Abstract
Cytosolic Ca(2+) overload induced by N-methyl-D-aspartate (NMDA) is one of the major causes for neuronal cell death during cerebral ischemic insult and neurodegenerative disorders. Previously, we have reported that the cytokine interleukin-6 (IL-6) reduces NMDA-induced cytosolic Ca(2+) overload by inhibiting both L-type voltage-gated calcium channel (L-VGCC) activity and intracellular Ca(2+) store release in cultured cerebellar granule neurons (CGNs). Here we aimed to show that NMDA-gated receptor channels (i.e., NMDA receptors, NMDARs) are an inhibitory target of IL-6 via a mediation of calcineurin (CaN) signaling. As expected, IL-6 decreased NMDAR-mediated cytosolic Ca(2+) overload and inward current in cultured CGNs. The NMDAR subunits, NR1, NR2A, NR2B and NR2C, were expressed in CGNs. Blocking either of NR2A, NR2B and NR2C with respective antagonist reduced NMDA-induced extracellular Ca(2+) influx and neuronal death. Importantly, the reduced percentages in extracellular Ca(2+) influx and neuronal death by either NR2B or NR2C antagonist were weaker in the presence of IL-6 than in the absence of IL-6, while the reduced percentage by NR2A antagonist was not significantly different between the presence and the absence of IL-6. AG490, an inhibitor of Janus kinase (JAK), abolished IL-6 protection against extracellular Ca(2+) influx, mitochondrial membrane depolarization, neuronal death, and CaN activity impairment induced by NMDA. The CaN inhibitor FK506 reduced these IL-6 neuroprotective properties. Collectively, these results suggest that IL-6 exerts neuroprotection by inhibiting activities of the NMDAR subunits NR2B and NR2C (but not NR2A) via the intermediation of JAK/CaN signaling.
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Affiliation(s)
- Song-Hua Ma
- Department of Physiology, School of Medicine, and Co-innovation Center of Neuroregeneration, Nantong University, 19 Qixiu Road, Nantong, Jiangsu Province 226001, China
| | - Qian-Xing Zhuang
- Department of Biological Science and Technology and State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Mailbox 426, 22 Hankou Road, Nanjing 210093, China
| | - Wei-Xing Shen
- Department of Physiology, School of Medicine, and Co-innovation Center of Neuroregeneration, Nantong University, 19 Qixiu Road, Nantong, Jiangsu Province 226001, China
| | - Yu-Ping Peng
- Department of Physiology, School of Medicine, and Co-innovation Center of Neuroregeneration, Nantong University, 19 Qixiu Road, Nantong, Jiangsu Province 226001, China.
| | - Yi-Hua Qiu
- Department of Physiology, School of Medicine, and Co-innovation Center of Neuroregeneration, Nantong University, 19 Qixiu Road, Nantong, Jiangsu Province 226001, China.
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10
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Fakira AK, Portugal GS, Carusillo B, Melyan Z, Morón JA. Increased small conductance calcium-activated potassium type 2 channel-mediated negative feedback on N-methyl-D-aspartate receptors impairs synaptic plasticity following context-dependent sensitization to morphine. Biol Psychiatry 2014; 75:105-14. [PMID: 23735878 PMCID: PMC3992971 DOI: 10.1016/j.biopsych.2013.04.026] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Revised: 04/17/2013] [Accepted: 04/29/2013] [Indexed: 12/21/2022]
Abstract
BACKGROUND Hippocampal long-term potentiation (LTP) is impaired following repeated morphine administration paired with a novel context. This procedure produces locomotor sensitization that can be abolished by blocking calcium (Ca(2+))-permeable alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors (AMPARs) in the hippocampus. However, the mechanisms underlying LTP impairment remain unclear. Here, we investigate the role of N-methyl-D-aspartate receptors (NMDARs), AMPARs, and small conductance Ca(2+)-activated potassium type 2 (SK2) channels in LTP induction after context-dependent sensitization to morphine. METHODS Mice were treated with saline or escalating doses of morphine (5, 8, 10, and 15 mg/kg) every 12 hours in a locomotor activity chamber and a challenge dose of 5 mg/kg morphine was given 1 week later. After the challenge, the hippocampi were removed to assay phosphatase 2A (PP2A) activity, NMDAR, and SK2 channel synaptic expression or to perform electrophysiological recordings. RESULTS Impaired hippocampal LTP, which accompanied morphine-induced context-dependent sensitization, could not be restored by blocking Ca(2+)-permeable AMPARs. Context-dependent sensitization to morphine altered hippocampal NMDAR subunit composition and enhanced the SK2 channel-mediated negative feedback on NMDAR. Increased PP2A activity observed following context-dependent sensitization suggests that the potentiated SK2 channel effect on NMDAR was mediated by increased SK2 sensitivity to Ca(2+). Finally, inhibition of SK2 channel or PP2A activity restored LTP. CONCLUSIONS Our studies demonstrate that the SK2 channel-NMDAR feedback loop plays a role in opiate-induced impairment of hippocampal plasticity and that the positive modulation of SK2 channels occurs via increases in PP2A activity. This provides further evidence that small conductance Ca(2+)-activated potassium channels play a role in drug-induced plasticity.
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Affiliation(s)
- Amanda K Fakira
- Department of Anesthesiology, College of Physicians and Surgeons, Columbia University Medical Center, New York, New York
| | - George S Portugal
- Department of Anesthesiology, College of Physicians and Surgeons, Columbia University Medical Center, New York, New York
| | - Brianna Carusillo
- Department of Anesthesiology, College of Physicians and Surgeons, Columbia University Medical Center, New York, New York
| | - Zare Melyan
- Department of Anesthesiology, College of Physicians and Surgeons, Columbia University Medical Center, New York, New York
| | - Jose A Morón
- Department of Anesthesiology, College of Physicians and Surgeons, Columbia University Medical Center, New York, New York.
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11
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Liu MG, Kang SJ, Shi TY, Koga K, Zhang MM, Collingridge GL, Kaang BK, Zhuo M. Long-term potentiation of synaptic transmission in the adult mouse insular cortex: multielectrode array recordings. J Neurophysiol 2013; 110:505-21. [PMID: 23636718 DOI: 10.1152/jn.01104.2012] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The insular cortex (IC) is widely believed to be an important forebrain structure involved in cognitive and sensory processes such as memory and pain. However, little work has been performed at the cellular level to investigate the synaptic basis of IC-related brain functions. To bridge the gap, the present study was designed to characterize the basic synaptic mechanisms for insular long-term potentiation (LTP). Using a 64-channel recording system, we found that an enduring form of late-phase LTP (L-LTP) could be reliably recorded for at least 3 h in different layers of IC slices after theta burst stimulation. The induction of insular LTP is protein synthesis dependent and requires activation of both GluN2A and GluN2B subunits of the NMDA receptor, L-type voltage-gated calcium channels, and metabotropic glutamate receptor 1. The paired-pulse facilitation ratio was unaffected by insular L-LTP induction, and expression of insular L-LTP required the recruitment of postsynaptic calcium-permeable AMPA receptors. Our results provide the first in vitro report of long-term multichannel recordings of L-LTP in the IC in adult mice and suggest its potential important roles in insula-related memory and chronic pain.
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Affiliation(s)
- Ming-Gang Liu
- Department of Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul, Korea
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12
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Dalton GL, Wu DC, Wang YT, Floresco SB, Phillips AG. NMDA GluN2A and GluN2B receptors play separate roles in the induction of LTP and LTD in the amygdala and in the acquisition and extinction of conditioned fear. Neuropharmacology 2012; 62:797-806. [DOI: 10.1016/j.neuropharm.2011.09.001] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Revised: 08/29/2011] [Accepted: 09/02/2011] [Indexed: 01/14/2023]
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13
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Han C, Quirion R, Zheng W. WITHDRAWN: Glutamate Attenuates IGF-1 Receptor Signaling via NR2B containing NMDA Receptors 3 and neuronal Nitric Oxide Synthase. Biochem Biophys Res Commun 2011:S0006-291X(11)01763-3. [PMID: 22001275 DOI: 10.1016/j.bbrc.2011.09.135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Accepted: 09/28/2011] [Indexed: 05/31/2023]
Abstract
This article has been withdrawn at the request of the authors. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy.
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Affiliation(s)
- Chao Han
- Neuropharmacology, School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou 510006, China
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Forebrain NR2B overexpression facilitating the prefrontal cortex long-term potentiation and enhancing working memory function in mice. PLoS One 2011; 6:e20312. [PMID: 21655294 PMCID: PMC3105019 DOI: 10.1371/journal.pone.0020312] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Accepted: 04/26/2011] [Indexed: 11/19/2022] Open
Abstract
Prefrontal cortex plays an important role in working memory, attention regulation and behavioral inhibition. Its functions are associated with NMDA receptors. However, there is little information regarding the roles of NMDA receptor NR2B subunit in prefrontal cortical synaptic plasticity and prefrontal cortex-related working memory. Whether the up-regulation of NR2B subunit influences prefrontal cortical synaptic plasticity and working memory is not yet clear. In the present study, we measured prefrontal cortical synaptic plasticity and working memory function in NR2B overexpressing transgenic mice. In vitro electrophysiological data showed that overexpression of NR2B specifically in the forebrain region resulted in enhancement of prefrontal cortical long-term potentiation (LTP) but did not alter long-term depression (LTD). The enhanced LTP was completely abolished by a NR2B subunit selective antagonist, Ro25-6981, indicating that overexpression of NR2B subunit is responsible for enhanced LTP. In addition, NR2B transgenic mice exhibited better performance in a set of working memory paradigms including delay no-match-to-place T-maze, working memory version of water maze and odor span task. Our study provides evidence that NR2B subunit of NMDA receptor in prefrontal cortex is critical for prefrontal cortex LTP and prefrontal cortex-related working memory.
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15
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Huang L, Balsara RD, Sheng Z, Castellino FJ. Conantokins inhibit NMDAR-dependent calcium influx in developing rat hippocampal neurons in primary culture with resulting effects on CREB phosphorylation. Mol Cell Neurosci 2010; 45:163-72. [PMID: 20600930 DOI: 10.1016/j.mcn.2010.06.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2010] [Revised: 06/10/2010] [Accepted: 06/11/2010] [Indexed: 11/29/2022] Open
Abstract
The effects of conantokin (con)-G, con-R[1-17], and con-T on ion flow through N-methyl-D-aspartate receptor (NMDAR) ion channels were determined in cultured primary rat hippocampal neurons. The potency of con-G diminished, whereas inhibition by con-R[1-17] and con-T did not change, as the neurons matured. Con-G, con-R[1-17], and con-T effectively diminished NMDA-induced Ca(2+) influx into the cells. A similar age-dependent decrease in con-G-mediated inhibition of the amplitude of spontaneous excitatory postsynaptic currents (sEPSCs) was observed, compared to con-R[1-17] and con-T. The effects of the conantokins on NMDA-induced cAMP response element-binding protein (CREB) phosphorylation in immature (DIV 9) and mature (DIV 16) neurons showed that, at DIV 9, con-G, con-R[1-17], and con-T inhibited NMDA-mediated P-CREB levels, whereas in DIV 16 neurons the conantokins did not inhibit overall levels of NMDA-induced P-CREB. In contrast, P-CREB levels were enhanced through inhibition of the protein phosphatases, PP1 and PP2B (calcineurin). This ability of conantokins to sustain CREB phosphorylation can thus enhance neuronal survival and plasticity.
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Affiliation(s)
- Luoxiu Huang
- WM Keck Center for Transgene Research, Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
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Peng YZ, Li XX, Wang YW. Effects of Parecoxib and Fentanyl on nociception-induced cortical activity. Mol Pain 2010; 6:3. [PMID: 20089200 PMCID: PMC2819047 DOI: 10.1186/1744-8069-6-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2009] [Accepted: 01/21/2010] [Indexed: 11/10/2022] Open
Abstract
Background Analgesics, including opioids and non-steroid anti-inflammatory drugs reduce postoperative pain. However, little is known about the quantitative effects of these drugs on cortical activity induced by nociceptive stimulation. The aim of the present study was to determine the neural activity in response to a nociceptive stimulus and to investigate the effects of fentanyl (an opioid agonist) and parecoxib (a selective cyclooxygenase-2 inhibitor) on this nociception-induced cortical activity evoked by tail pinch. Extracellular recordings (electroencephalogram and multi-unit signals) were performed in the area of the anterior cingulate cortex while intracellular recordings were made in the primary somatosensory cortex. The effects of parecoxib and fentanyl on induced cortical activity were compared. Results Peripheral nociceptive stimulation in anesthetized rats produced an immediate electroencephalogram (EEG) desynchronization resembling the cortical arousal (low-amplitude, fast-wave activity), while the membrane potential switched into a persistent depolarization state. The induced cortical activity was abolished by fentanyl, and the fentanyl's effect was reversed by the opioid receptor antagonist, naloxone. Parecoxib, on the other hand, did not significantly affect the neural activity. Conclusion Cortical activity was modulated by nociceptive stimulation in anesthetized rats. Fentanyl showed a strong inhibitory effect on the nociceptive-stimulus induced cortical activity while parecoxib had no significant effect.
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Affiliation(s)
- Yuan-Zhi Peng
- Department of Anesthesiology, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200092, China
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Wu LJ, Zhuo M. Targeting the NMDA receptor subunit NR2B for the treatment of neuropathic pain. Neurotherapeutics 2009; 6:693-702. [PMID: 19789073 PMCID: PMC5084290 DOI: 10.1016/j.nurt.2009.07.008] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2009] [Accepted: 07/09/2009] [Indexed: 11/26/2022] Open
Abstract
Neuropathic pain is generally defined as a chronic pain state resulting from peripheral or central nerve injury, or both. An effective treatment for neuropathic pain is still lacking. The NMDA receptor, one type of the ionotropic glutamate receptors, is known to be important for triggering long-lasting changes in synapses. NMDA receptor-dependent synaptic plasticity plays roles not only in physiological functions such as learning and memory, but also in unwanted pathological conditions such as chronic pain. This review addresses recent progress on NMDA receptors in neuropathic pain, with particular emphasis on the NR2B-subunit-containing receptors. The expression and function of NMDA receptors in synaptic plasticity in the pain transmission pathway from dorsal root ganglia to the anterior cingulate cortex is reviewed, and preclinical and clinical investigations of selective NMDA receptor in neuropathic pain are discussed. The NMDA receptors, in particular NR2B-containing NMDA receptors, serve as promising targets for treatment of neuropathic pain.
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Affiliation(s)
- Long-Jun Wu
- grid.17063.33Department of Physiology, Faculty of Medicine, University of Toronto Centre for the Study of Pain, University of Toronto, 1 King’s College Circle, M5S 1A8 Toronto, Ontario Canada
| | - Min Zhuo
- grid.17063.33Department of Physiology, Faculty of Medicine, University of Toronto Centre for the Study of Pain, University of Toronto, 1 King’s College Circle, M5S 1A8 Toronto, Ontario Canada
- grid.31501.360000000404705905Department of Brain and Cognitive Sciences, Seoul National University, 151-746 Seoul, Korea
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Reduced spatial learning in mice treated with NVP-AAM077 through down-regulating neurogenesis. Eur J Pharmacol 2009; 622:37-44. [PMID: 19765576 DOI: 10.1016/j.ejphar.2009.09.031] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2009] [Revised: 09/01/2009] [Accepted: 09/10/2009] [Indexed: 01/17/2023]
Abstract
NR2A-containing N-methyl-D-aspartate (NMDA) receptors have important roles in influencing the long-term potentiation and spatial memory. Here using Morris water maze, we found that inhibition of NR2A-containing NMDA receptors by [(R)-[(S)-1-(4-bromophenyl)-ethylamino]-(2, 3-dioxo-1,2,3,4-tetrahydroquinoxalin-5-yl)-methyl]-phosphonic acid (NVP-AAM077) hindered the formation of spatial memory. An increasing number of reports suggest that adult hippocampal neurogenesis is involved in hippocampal-mediated learning. To explore the possible mechanisms understanding the reduced spatial memory by NVP-AAM077, we investigated the effects of NVP-AAM077 on neurogenesis. We found that NVP-AAM077 inhibited progenitor cells proliferation in the subventricular zone and dentate gyrus and reduced the survival of newborn cells in the dentate gyrus in the adult mice. In null mutant mice lacking neuronal nitric oxide synthase (nNOS) gene (nNOS(-/-)), the effects of NVP-AAM077 on neurogenesis disappeared. In addition, NVP-AAM077 increased nNOS enzymatic activity. Our findings suggest that NVP-AAM077 reduced spatial learning through down-regulating neurogenesis in the adult hippocampus.
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Muller T, Albrecht D, Gebhardt C. Both NR2A and NR2B subunits of the NMDA receptor are critical for long-term potentiation and long-term depression in the lateral amygdala of horizontal slices of adult mice. Learn Mem 2009; 16:395-405. [DOI: 10.1101/lm.1398709] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Fan J, Wu X, Cao Z, Chen S, Owyang C, Li Y. Up-regulation of anterior cingulate cortex NR2B receptors contributes to visceral pain responses in rats. Gastroenterology 2009; 136:1732-1740.e3. [PMID: 19208366 PMCID: PMC2677121 DOI: 10.1053/j.gastro.2009.01.069] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2008] [Revised: 12/19/2008] [Accepted: 01/29/2009] [Indexed: 12/02/2022]
Abstract
BACKGROUND & AIMS Electrophysiologic and behavioral studies have shown that increased N-methyl-D-aspartate (NMDA)-receptor activation of anterior cingulate cortex (ACC) neurons has a critical role in modulating visceral pain responses in viscerally hypersensitive (VH) rats. This study aimed to identify the NMDA receptor subtypes in perigenual ACC (pACC) neurons involved in the facilitation of visceral nociception. METHODS We performed in vivo electrophysiologic recordings of pACC neurons and examined the visceromotor response (VMR) to colorectal distention (CRD) in normal and VH rats induced by colonic anaphylaxis. The NR2A-subtype-receptor antagonist [(R)-[(S)-1-(4-bromo-phenyl)-ethylamino]-(2,3-dioxo-1,2,3,4-tetrahydroquinoxalin-5-yl)-methyl]-phosphonic acid (NVP-AAM077) and the NR2B-receptor-antagonist Ro25-6981 were microinjected into the pACC. To down-regulate NR2B-receptor gene expression, an NR2B-specific small interfering RNA (siRNA) and a plasmid (pEGFP-N1) that expressed the green fluorescent protein were administered into ACC neurons by electroporation. RESULTS Reverse microdialysis of NVP-AAM077 had no effect on basal and CRD-induced ACC neuronal firing in VH and control groups. In VH rats, Ro25-6981 (500 micromol/L) inhibited ACC neuronal firing, evoked by 30 and 50 mm Hg CRD, by 98% and 52%, respectively. NVP-AAM077 did not affect the VMR in either group. Ro25-6981 significantly suppressed the VMR in VH but not normal rats. Immunoblot analysis showed increased NR2B-receptor expression in the pACC of VH rats. NR2B siRNA-treated VH rats showed a significant reduction in the VMR, compared with controls. CONCLUSIONS The NR2B subunit of the NMDA receptor has a critical role in the modulation of ACC sensitization and visceral pain responses in VH rats.
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Affiliation(s)
- Jing Fan
- Gastroenterology Research Unit, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Xiaoyin Wu
- Gastroenterology Research Unit, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Zhijun Cao
- Gastroenterology Research Unit, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Shengliang Chen
- Gastroenterology Research Unit, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Chung Owyang
- Gastroenterology Research Unit, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Ying Li
- Gastroenterology Research Unit, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan.
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Induction- and conditioning-protocol dependent involvement of NR2B-containing NMDA receptors in synaptic potentiation and contextual fear memory in the hippocampal CA1 region of rats. Mol Brain 2008; 1:9. [PMID: 18826591 PMCID: PMC2570668 DOI: 10.1186/1756-6606-1-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2008] [Accepted: 09/30/2008] [Indexed: 11/11/2022] Open
Abstract
Long-term potentiation (LTP) in the hippocampal CA1 region requires the activation of N-methyl-D-aspartate receptors (NMDARs). Studies using genetic and pharmacological approaches have reported inconsistent results of the requirement of NR2B-containing NMDARs in LTP in the CA1 region. Pharmacological studies showed that NR2B-containing NMDARs are not required for LTP, while genetic studies reported that over-expression of NR2B-NMDARs enhances LTP and hippocampus-dependent memory. Here, we provide evidence showing that the functional role of NR2B-NMDARs in hippocampal LTP and memory depends on LTP-inducing and behavior-conditioning protocols. Inhibition of NR2B-NMDARs with the NR2B selective antagonist ifenprodil or Ro25-6981 suppressed LTP induced by spike-timing protocol, with no impact on LTP induced by pairing protocol or two-train high-frequency stimulation (HFS) protocol. Inhibition of NR2B-NMDARs did not affect the late phase LTP induced by four-train HFS. Ca2+ imaging showed that there was difference in kinetics of intracellular Ca2+ signals induced by spiking-timing and pairing protocols. Pre-training intra-CA1 infusion of ifenprodil or Ro25-6981 impaired the contextual fear memory induced by five CS-US pairings, with no effect on the memory induced by one CS-US pairing.
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Sun YG, Gao YJ, Zhao ZQ, Huang B, Yin J, Taylor GA, Chen ZF. Involvement of P311 in the affective, but not in the sensory component of pain. Mol Pain 2008; 4:23. [PMID: 18549486 PMCID: PMC2459156 DOI: 10.1186/1744-8069-4-23] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2008] [Accepted: 06/12/2008] [Indexed: 11/12/2022] Open
Abstract
Pain is comprised of the sensory and affective components. Compared to the well-investigated mechanisms of the sensory pain, much less is known about the mechanisms underlying the affective pain. In recent years, accumulating evidence suggests that the anterior cingulate cortex (ACC) is a key structure for pain affection. To identify the molecules that may be involved in the affective component of pain, we have searched the Allen Brain Atlas expression database for genes whose expression is enriched in the ACC, and found that P311, an 8-kDa peptide, showed the strong expression in the ACC. P311 is also expressed in other areas associated with pain affection including the amygdala, insular cortex and thalamus. To understand the role of P311 in pain perception, we have examined the pain behaviors of the mice lacking P311. P311-/- mice showed normal heat and mechanical sensitivity, as well as normal formalin-induced inflammatory pain. In contrast, the formalin-induced avoidance behavior, which reflects pain-related negative emotion, was significantly attenuated in P311-/- mice relative to the control mice. These results suggest that P311 is involved in the affective, but not in the sensory component of pain. Our study thus provides the first evidence suggesting that the affective and sensory pain may be regulated by distinct molecular mechanisms.
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Affiliation(s)
- Yan-Gang Sun
- Departments of Anesthesiology, Washington University School of Medicine Pain Center, St, Louis, Missouri 63110, USA.
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23
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Cortical excitation and chronic pain. Trends Neurosci 2008; 31:199-207. [PMID: 18329111 DOI: 10.1016/j.tins.2008.01.003] [Citation(s) in RCA: 405] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2007] [Revised: 01/24/2008] [Accepted: 01/28/2008] [Indexed: 02/08/2023]
Abstract
Investigation of the basic mechanisms of chronic pain not only provides insights into how the brain processes and modulates sensory information but also provides the basis for designing novel treatments for currently intractable clinical conditions. Human brain imaging studies have revealed new roles of cortical neuronal networks in chronic pain, including its unpleasant quality, and mouse studies have provided molecular and synaptic mechanisms underlying relevant cortical plasticity. This review paper will critically examine the current literature and propose a cortical network model for chronic pain.
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Abstract
The cellular basis underlying the complex clinical symptomatology of bipolar disorder and the mechanisms underlying the actions of its effective treatments have not yet been fully elucidated. This study investigated the role of hippocampal synaptic AMPA receptors. We found that chronic administration of the antimanic agents lithium and valproate (VPA) reduced synaptic AMPA receptor GluR1/2 in hippocampal neurons in vitro and in vivo. Electrophysiological studies confirmed that the AMPA/NMDA ratio was reduced in CA1 regions of hippocampal slices from lithium-treated animals. Reduction in GluR1 phosphorylation at its cAMP-dependent protein kinase A site by the synthetic peptide TAT-S845, which mimics the effects of lithium or VPA, was sufficient to attenuate surface and synaptic GluR1/2 levels in hippocampal neurons in vitro and in vivo. Intrahippocampal infusion studies with the AMPA-specific inhibitor GYKI 52466 [4-(8-methyl-9H-1,3-dioxolo[4,5-h][2,3]benzodiazepin-5-yl)-benzenamine hydrochloride], a GluR1-specific TAT-S845 peptide, showed that GluR1/2 was essential for the development of manic/hedonic-like behaviors such as amphetamine-induced hyperactivity. These studies provide novel insights into the role of hippocampal GluR1/2 receptors in mediating facets of the manic syndrome and offer avenues for the development of novel therapeutics for these disorders.
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