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Effects of Low Doses of Ketamine on Pyramidal Neurons in Rat Prefrontal Cortex. Neuroscience 2018; 384:178-187. [DOI: 10.1016/j.neuroscience.2018.05.037] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 05/22/2018] [Accepted: 05/23/2018] [Indexed: 12/30/2022]
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Yoon MS, Koh CS, Lee J, Shin J, Kong C, Jung HH, Chang JW. Injecting NMDA and Ro 25-6981 in insular cortex induce neuroplastic changes and neuropathic pain-like behaviour. Eur J Pain 2018; 22:1691-1700. [PMID: 29862605 DOI: 10.1002/ejp.1254] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/28/2018] [Indexed: 12/15/2022]
Abstract
BACKGROUND Neuropathic pain is associated with abnormal sensitivity of the central nervous system. Although the mechanism underlying the development of sensitization remains to be fully elucidated, recent studies have reported that neuroplastic changes in the pain circuitry may be involved in hypersensitivity associated with neuropathic pain. However, it is difficult to investigate such phenomena in existing animal pain model. Therefore, in this study, we developed a novel animal model - the circuit plasticity reconstruction (CPR) model - to mimic central sensitization associated with neuroplastic changes. METHOD NMDA and Ro 25-6981 were injected into the right insular cortex of Sprague-Dawley rats, while electrical stimulation was delivered to the contralateral hind paw. Mechanical allodynia was tested by von Frey test with up-down method, and neuroplastic changes were confirmed by PSA-NCAM-positive immunostaining. RESULT The mechanical withdrawal threshold of the left hind paw decreased beginning 1 day after CPR modelling and persisted until day 21 comparing to the modified CPR 1 (mod-CPR 1) group (CPR: 91.68 ± 1.8%, mod-CPR 1: 42.71 ± 3.4%, p < 0.001). In contrast, mod-CPR 2 surgery without electrical stimulation did not induce mechanical allodynia. Immunostaining for PSA-NCAM also revealed that neuroplastic changes had occurred in the CPR group. CONCLUSION Our results demonstrated that CPR modelling induced neuroplasticity within the insular cortex, leading to alterations in the neural circuitry and central sensitization. SIGNIFICANCE This article represents that the CPR model can mimic the neuropathic pain derived by neuroplastic changes. Our findings indicate that the CPR model may aid the development of novel therapeutic strategies for neuropathic pain and in elucidating the mechanisms underlying pain induced by central sensitization and neuroplastic changes.
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Affiliation(s)
- M S Yoon
- Department of Neurosurgery, Yonsei University College of Medicine, Seoul, South Korea.,Brain Korea 21 PLUS Project for Medical Science and Brain Research Institute, Yonsei University College of Medicine, Seoul, Korea
| | - C S Koh
- Department of Neurosurgery, Yonsei University College of Medicine, Seoul, South Korea
| | - J Lee
- Department of Neurosurgery, Yonsei University College of Medicine, Seoul, South Korea.,Brain Korea 21 PLUS Project for Medical Science and Brain Research Institute, Yonsei University College of Medicine, Seoul, Korea
| | - J Shin
- Department of Neurosurgery, Yonsei University College of Medicine, Seoul, South Korea.,Brain Korea 21 PLUS Project for Medical Science and Brain Research Institute, Yonsei University College of Medicine, Seoul, Korea
| | - C Kong
- Department of Neurosurgery, Yonsei University College of Medicine, Seoul, South Korea
| | - H H Jung
- Department of Neurosurgery, Yonsei University College of Medicine, Seoul, South Korea.,Brain Korea 21 PLUS Project for Medical Science and Brain Research Institute, Yonsei University College of Medicine, Seoul, Korea
| | - J W Chang
- Department of Neurosurgery, Yonsei University College of Medicine, Seoul, South Korea.,Brain Korea 21 PLUS Project for Medical Science and Brain Research Institute, Yonsei University College of Medicine, Seoul, Korea
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Li YJ, Ping XJ, Qi C, Shen F, Sun LL, Sun XW, Ge FF, Xing GG, Cui CL. Re-exposure to morphine-associated context facilitated long-term potentiation in the vSUB-NAc glutamatergic pathway via GluN2B-containing receptor activation. Addict Biol 2017; 22:435-445. [PMID: 26692025 DOI: 10.1111/adb.12343] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Revised: 09/29/2015] [Accepted: 11/04/2015] [Indexed: 12/28/2022]
Abstract
The glutamatergic projection from the ventral subiculum of the hippocampus (vSUB) to the nucleus accumbens (NAc) shell has been reported to play a key role in drug-related behavior. The GluN2B subunit of N-methyl-D-aspartate receptors (NMDARs) in the NAc can be selectively elevated after the retrieval of drug-conditioned memory. However, whether the increased GluN2B-containing NMDARs (GluN2B-NMDARs) are able to alter the synaptic plasticity of the vSUB-NAc glutamatergic pathway remains unclear. Here, we found that the long-term potentiation (LTP) in the vSUB-NAc pathway was facilitated and the GluN2B subunit protein level was elevated in synaptoneurosomes of the NAc shell, but not in the core, following morphine-induced conditioned place preference (CPP) expression in rats. The facilitated LTP was prevented by the GluN2B-NMDAR antagonist RO25-6981. Also, a neurochemical disconnection following microinjection of RO25-6981 into the NAc shell, plus microinfusion of GABA agonist baclofen and muscimol into the contralateral vSUB prevented the expression of morphine-induced CPP. These findings suggest that the retrieval of drug-associated memory potentiated synaptic plasticity in the vSUB-NAc pathway, which was dependent on GluN2B-NMDAR activation in the NAc shell. These findings provide a new explanation for the mechanisms that underlie the morphine-associated-context memory. The GluN2B-NMDARs may be regarded as a potential target for erasing morphine-related memory.
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Affiliation(s)
- Yi-Jing Li
- Neuroscience Research Institute; Peking University; Beijing China
- Department of Neurobiology, School of Basic Medical Sciences; Peking University; Beijing China
- Key Laboratory for Neuroscience; Ministry of Education; Beijing China
- Key Laboratory for Neuroscience; Ministry of National Health and Family Planning Commission; Beijing China
| | - Xing-Jie Ping
- Neuroscience Research Institute; Peking University; Beijing China
- Department of Neurobiology, School of Basic Medical Sciences; Peking University; Beijing China
- Key Laboratory for Neuroscience; Ministry of Education; Beijing China
- Key Laboratory for Neuroscience; Ministry of National Health and Family Planning Commission; Beijing China
| | - Chong Qi
- Neuroscience Research Institute; Peking University; Beijing China
- Department of Neurobiology, School of Basic Medical Sciences; Peking University; Beijing China
- Key Laboratory for Neuroscience; Ministry of Education; Beijing China
- Key Laboratory for Neuroscience; Ministry of National Health and Family Planning Commission; Beijing China
| | - Fang Shen
- Neuroscience Research Institute; Peking University; Beijing China
- Department of Neurobiology, School of Basic Medical Sciences; Peking University; Beijing China
- Key Laboratory for Neuroscience; Ministry of Education; Beijing China
- Key Laboratory for Neuroscience; Ministry of National Health and Family Planning Commission; Beijing China
| | - Lin-Lin Sun
- Neuroscience Research Institute; Peking University; Beijing China
- Department of Neurobiology, School of Basic Medical Sciences; Peking University; Beijing China
- Key Laboratory for Neuroscience; Ministry of Education; Beijing China
- Key Laboratory for Neuroscience; Ministry of National Health and Family Planning Commission; Beijing China
| | - Xiao-Wei Sun
- Neuroscience Research Institute; Peking University; Beijing China
- Department of Neurobiology, School of Basic Medical Sciences; Peking University; Beijing China
- Key Laboratory for Neuroscience; Ministry of Education; Beijing China
- Key Laboratory for Neuroscience; Ministry of National Health and Family Planning Commission; Beijing China
| | - Fei-Fei Ge
- Neuroscience Research Institute; Peking University; Beijing China
- Department of Neurobiology, School of Basic Medical Sciences; Peking University; Beijing China
- Key Laboratory for Neuroscience; Ministry of Education; Beijing China
- Key Laboratory for Neuroscience; Ministry of National Health and Family Planning Commission; Beijing China
| | - Guo-Gang Xing
- Neuroscience Research Institute; Peking University; Beijing China
- Department of Neurobiology, School of Basic Medical Sciences; Peking University; Beijing China
- Key Laboratory for Neuroscience; Ministry of Education; Beijing China
- Key Laboratory for Neuroscience; Ministry of National Health and Family Planning Commission; Beijing China
| | - Cai-Lian Cui
- Neuroscience Research Institute; Peking University; Beijing China
- Department of Neurobiology, School of Basic Medical Sciences; Peking University; Beijing China
- Key Laboratory for Neuroscience; Ministry of Education; Beijing China
- Key Laboratory for Neuroscience; Ministry of National Health and Family Planning Commission; Beijing China
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Garzón-Niño J, Rodríguez-Muñoz M, Cortés-Montero E, Sánchez-Blázquez P. Increased PKC activity and altered GSK3β/NMDAR function drive behavior cycling in HINT1-deficient mice: bipolarity or opposing forces. Sci Rep 2017; 7:43468. [PMID: 28240305 PMCID: PMC5327482 DOI: 10.1038/srep43468] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 01/25/2017] [Indexed: 01/18/2023] Open
Abstract
Mice with histidine triad nucleotide-binding protein 1 (HINT1) deletion exhibit manic-like symptoms that evolve into depressive-like behavior in response to stressful paradigms. Molecular and electrophysiological studies have indicated that HINT1−/− mice exhibit increased PKC, PKA, and GSK3β activities, as well as glutamate N-methyl-D-aspartate receptor (NMDAR)/α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic receptor (AMPAR) and NR2B/NR2A subunit ratios. Pharmacological interventions stabilized their behavior but through different mechanisms. GSK3β inhibitors and valproate directly attenuated the expression of the manic-like symptoms, whereas PKC inhibition, lamotrigine, or risperidone promoted NMDAR-mediated depressive-like behaviors that counterbalanced the preexisting manic-like symptoms. Naïve HINT1−/− mice exposed to stressful paradigms rapidly manifested depressive-like behaviors in subsequent stressful situations, a capacity that persisted for a couple of weeks thereafter. During the depressive-like phase, citalopram, amitriptyline and MK801 precipitated manic-like behaviors in stressed HINT1−/− mice. Notably, the antagonism of NMDARs prevented HINT1−/− mice from alternating behaviors in response to stress. A comparison with “manic” Black Swiss mice indicated that in HINT1−/− mice, PKC supports manic-like symptoms and reduces the expression of depressive-like behaviors via activation of GSK3β and regulation of NR2B-enriched NMDARs. HINT1−/− mice represent a suitable model for studying human BPD and may facilitate the identification of novel targets and drugs to treat this mental disorder.
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Affiliation(s)
- Javier Garzón-Niño
- Neuropharmacology, Department of Translational Neurosciences, Instituto Cajal, CSIC, Madrid E-28002, Spain
| | - María Rodríguez-Muñoz
- Neuropharmacology, Department of Translational Neurosciences, Instituto Cajal, CSIC, Madrid E-28002, Spain
| | - Elsa Cortés-Montero
- Neuropharmacology, Department of Translational Neurosciences, Instituto Cajal, CSIC, Madrid E-28002, Spain
| | - Pilar Sánchez-Blázquez
- Neuropharmacology, Department of Translational Neurosciences, Instituto Cajal, CSIC, Madrid E-28002, Spain
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Kumar G, Olley J, Steckler T, Talpos J. Dissociable effects of NR2A and NR2B NMDA receptor antagonism on cognitive flexibility but not pattern separation. Psychopharmacology (Berl) 2015; 232:3991-4003. [PMID: 26184010 DOI: 10.1007/s00213-015-4008-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 06/28/2015] [Indexed: 12/29/2022]
Abstract
RATIONALE N-methyl-D-aspartate (NMDA) receptors play crucial roles in learning and memory, but the role of each NMDA receptor subtype in a specific cognitive process is unclear. Non-selective blockers of NMDA receptor are used to model the cognitive impairment in schizophrenia and Alzheimer's disease. Counter-intuitively selective NR2A and 2B NMDA receptor antagonists are thought to have pro-cognitive properties. These seemingly contrasting findings might in part be the result of different compounds and behavioral measures used across studies. OBJECTIVE We compared the effect of NVP-AAM077 (NR2A antagonist), CP 101-606 (NR2B antagonist), and MK-801 (non-selective antagonist) in a series of touch screen tasks that can be used to measure spatial cognition and cognitive flexibility. METHODS NVP-AAM077, CP 101-606, and MK-801 were administered prior to testing, in adult male Lister-hooded rats trained in tasks of location discrimination, paired associate learning (PAL), and trial unique non-match to location (TUNL). RESULTS Results showed that MK-801 impaired performance on all the tasks. In contrast, CP 101-606 only impaired reversal learning in location discrimination and had minimal effect on working memory in TUNL and caused a modest improvement in accuracy in PAL and acquisition of a spatial discrimination. NVP-AAM077 had little effect on performance across tasks, although these data allude to a potential enhancement of acquisition of a spatial location and impairments in spatial reversal learning in a separation-dependent manner. CONCLUSIONS These data demonstrated that non-selective NMDA antagonism will disrupt numerous aspects of cognitive function. However, selective antagonism is capable of impairing or enhancing cognitive function in a task-dependent fashion.
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Affiliation(s)
- Gaurav Kumar
- Janssen Research & Development, Turnhoutseweg 30, 2340, Beerse, Belgium.
| | - Joseph Olley
- Janssen Research & Development, Turnhoutseweg 30, 2340, Beerse, Belgium
| | - Thomas Steckler
- Janssen Research & Development, Turnhoutseweg 30, 2340, Beerse, Belgium
| | - John Talpos
- Janssen Research & Development, Turnhoutseweg 30, 2340, Beerse, Belgium
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Li S, Wang SU, Guo ZG, Huang N, Zhao FR, Zhu ML, Ma LJ, Liang JY, Zhang YL, Huang ZL, Wan GR. Protective effect of Xingnaojia formulation on rats with brain and liver damage caused by chronic alcoholism. Exp Ther Med 2015; 10:1643-1652. [PMID: 26640531 PMCID: PMC4665616 DOI: 10.3892/etm.2015.2773] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Accepted: 07/31/2015] [Indexed: 01/08/2023] Open
Abstract
The aim of this study was to observe the effect of a formulation of traditional Chinese medicine extracts known as Xingnaojia (XNJ) on the liver function, learning ability and memory of rats with chronic alcoholism and to verify the mechanism by which it protects the brain and liver. A rat model of chronic alcoholism was used in the study. The spatial learning ability and memory of the rats were tested. The rats were then sacrificed and their brains and hepatic tissues were isolated. The activity of superoxide dismutase (SOD) and levels of glutamate (Glu), N-methyl D-aspartate receptor subtype 2B (NR2B), cyclin-dependent kinase 5 (CDK5) and cannabinoid receptor 1 (CB1) in the hippocampus were analyzed. The ultrastructure of the hepatic tissue was observed by electron microscopy. In addition, the activities of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) in serum were tested and the levels of low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglycerides (TG) and total cholesterol (TCHOL) were analyzed. XNJ enhanced the learning and memory of rats with chronic alcoholism. Treatment with XNJ increased the activity of SOD, and decreased the expression levels of NR2B mRNA and NR2B, CB1 and CDK5 proteins in the brain tissues compared with those in the model rats. It also increased the activity of ALDH in the serum and liver, decreased the serum levels of LDL, TG and TCHOL and increased the serum level of HDL. These results indicate that XNJ exhibited a protective effect against brain and liver damage in rats with chronic alcoholism.
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Affiliation(s)
- Shuang Li
- School of Basic Medical Sciences, Xinxiang Medical University, Xinxiang, Henan 453003, P.R. China
| | - S U Wang
- College of Pharmacy, The Third Affiliated Hospital, Xinxiang Medical University, Xinxiang, Henan 453003, P.R. China
| | - Zhi-Gang Guo
- School of Basic Medical Sciences, Xinxiang Medical University, Xinxiang, Henan 453003, P.R. China
| | - Ning Huang
- College of Pharmacy, Xinxiang Medical University, Xinxiang, Henan 453003, P.R. China
| | - Fan-Rong Zhao
- College of Pharmacy, Xinxiang Medical University, Xinxiang, Henan 453003, P.R. China
| | - Mo-Li Zhu
- College of Pharmacy, Xinxiang Medical University, Xinxiang, Henan 453003, P.R. China
| | - Li-Juan Ma
- College of Pharmacy, Xinxiang Medical University, Xinxiang, Henan 453003, P.R. China
| | - Jin-Ying Liang
- College of Pharmacy, Xinxiang Medical University, Xinxiang, Henan 453003, P.R. China
| | - Yu-Lin Zhang
- College of Pharmacy, Xinxiang Medical University, Xinxiang, Henan 453003, P.R. China
| | - Zhong-Lin Huang
- College of Pharmacy, Xinxiang Medical University, Xinxiang, Henan 453003, P.R. China
| | - Guang-Rui Wan
- School of Basic Medical Sciences, Xinxiang Medical University, Xinxiang, Henan 453003, P.R. China
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Gupta-Agarwal S, Jarome TJ, Fernandez J, Lubin FD. NMDA receptor- and ERK-dependent histone methylation changes in the lateral amygdala bidirectionally regulate fear memory formation. Learn Mem 2014; 21:351-62. [PMID: 24939839 PMCID: PMC4061426 DOI: 10.1101/lm.035105.114] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
It is well established that fear memory formation requires de novo gene transcription in the amygdala. We provide evidence that epigenetic mechanisms in the form of histone lysine methylation in the lateral amygdala (LA) are regulated by NMDA receptor (NMDAR) signaling and involved in gene transcription changes necessary for fear memory consolidation. Here we found increases in histone H3 lysine 9 dimethylation (H3K9me2) levels in the LA at 1 h following auditory fear conditioning, which continued to be temporally regulated up to 25 h following behavioral training. Additionally, we demonstrate that inhibiting the H3K9me2 histone lysine methyltransferase G9a (H/KMTs-G9a) in the LA impaired fear memory, while blocking the H3K9me2 histone lysine demethylase LSD1 (H/KDM-LSD1) enhanced fear memory, suggesting that H3K9me2 in the LA can bidirectionally regulate fear memory formation. Furthermore, we show that NMDAR activity differentially regulated the recruitment of H/KMT-G9a, H/KDM-LSD1, and subsequent H3K9me2 levels at a target gene promoter. This was largely regulated by GluN2B- but not GluN2A-containing NMDARs via ERK activation. Moreover, fear memory deficits associated with NMDAR or ERK blockade were successfully rescued through pharmacologically inhibiting LSD1, suggesting that enhancements of H3K9me2 levels within the LA can rescue fear memory impairments that result from hypofunctioning NMDARs or loss of ERK signaling. Together, the present study suggests that histone lysine methylation regulation in the LA via NMDAR-ERK-dependent signaling is involved in fear memory formation.
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Affiliation(s)
- Swati Gupta-Agarwal
- Department of Neurobiology, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
| | - Timothy J Jarome
- Department of Neurobiology, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
| | - Jordan Fernandez
- Department of Neurobiology, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
| | - Farah D Lubin
- Department of Neurobiology, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
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Redistribution of ionotropic glutamate receptors detected by laser microdissection of the rat dentate gyrus 48 h following LTP induction in vivo. PLoS One 2014; 9:e92972. [PMID: 24667777 PMCID: PMC3965487 DOI: 10.1371/journal.pone.0092972] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2013] [Accepted: 02/27/2014] [Indexed: 11/25/2022] Open
Abstract
The persistence and input specificity of long-term potentiation (LTP) make it attractive as a mechanism of information storage. In its initial phase, both in vivo and in vitro studies have shown that LTP is associated with increased membrane localization of AMPA receptor subunits, but the molecular basis of LTP maintenance over the long-term is still unclear. We have previously shown that expression of AMPA and NMDA receptor subunits is elevated in whole homogenates prepared from dentate gyrus 48 h after LTP induction in vivo. In the present study, we utilized laser microdissection (LMD) techniques to determine whether AMPA and NMDA receptor upregulation occurs specifically in the stimulated regions of the dentate gyrus dendritic arbor. Receptor proteins GluN1, GluA1 and GluA2, as well as postsynaptic density protein of 95 kDa and tubulin were detected by Western blot analysis in microdissected samples. Gradients of expression were observed for GluN1 and GluA2, decreasing from the inner to the outer zones of the molecular layer, and were independent of LTP. When induced at medial perforant path synapses, LTP was associated with an apparent specific redistribution of GluA1 and GluN1 to the middle molecular layer that contains these synapses. These data indicate that glutamate receptor proteins are delivered specifically to dendritic regions possessing LTP-expressing synapses, and that these changes are preserved for at least 48 h.
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Kunda S, Cheriyan J, Hur M, Balsara RD, Castellino FJ. Antagonist properties of Conus parius peptides on N-methyl-D-aspartate receptors and their effects on CREB signaling. PLoS One 2013; 8:e81405. [PMID: 24260577 PMCID: PMC3832412 DOI: 10.1371/journal.pone.0081405] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 10/22/2013] [Indexed: 02/05/2023] Open
Abstract
Three members of a family of small neurotoxic peptides from the venom of Conus parius, conantokins (Con) Pr1, Pr2, and Pr3, function as antagonists of N-methyl-D-aspartate receptors (NMDAR). We report structural characterizations of these synthetic peptides, and also demonstrate their antagonistic properties toward ion flow through NMDAR ion channels in primary neurons. ConPr1 and ConPr2 displayed moderate increases in α-helicity after addition of Mg2+. Native apo-ConPr3 possessed an α-helical conformation, and the helicity increased only slightly on addition of Mg2+. Additionally, these peptides diminished NMDA/Gly-mediated currents and intracellular Ca2+ (iCa2+) influx in mature rat primary hippocampal neurons. Electrophysiological data showed that these peptides displayed slower antagonistic properties toward the NMDAR than conantokins from other species of cone snails, e.g., ConT and ConG. Furthermore, to demonstrate selectivity of the C. parius-derived conantokins towards specific NMDAR subunits, cortical neurons from GluN2A-/- and GluN2B-/- mice were utilized. Robust inhibition of NMDAR-mediated stimulation in GluN2A-/--derived mouse neurons, as compared to those isolated from GluN2B-/--mouse brains, was observed, suggesting a greater selectivity of these antagonists towards the GluN2B subunit. These C. parius conantokins mildly inhibited NMDAR-induced phosphorylation of CREB at Ser133, suggesting that the peptides modulated iCa2+ entry and, thereby, activation of CREB, a transcription factor that is required for maintaining long-term synaptic activity. Our data mechanistically show that while these peptides effectively antagonize NMDAR-directed current and iCa2+ influx, receptor-coupled CREB signaling is maintained. The consequence of sustained CREB signaling is improved neuronal plasticity and survival during neuropathologies.
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Affiliation(s)
- Shailaja Kunda
- W.M. Keck Center for Transgene Research and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - John Cheriyan
- W.M. Keck Center for Transgene Research and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Michael Hur
- W.M. Keck Center for Transgene Research and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Rashna D. Balsara
- W.M. Keck Center for Transgene Research and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Francis J. Castellino
- W.M. Keck Center for Transgene Research and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, United States of America
- * E-mail:
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Abstract
Emerging data indicate that growth hormone (GH) therapy could have a role in improving cognitive function. GH replacement therapy in experimental animals and human patients counteracts the dysfunction of many behaviours related to the central nervous system (CNS). Various behaviours, such as cognitive behaviours related to learning and memory, are known to be induced by GH; the hormone might interact with specific receptors located in areas of the CNS that are associated with the functional anatomy of these behaviours. GH is believed to affect excitatory circuits involved in synaptic plasticity, which alters cognitive capacity. GH also has a protective effect on the CNS, as indicated by its beneficial effects in patients with spinal cord injury. Data collected from animal models indicates that GH might also stimulate neurogenesis. This Review discusses the mechanisms underlying the interactions between GH and the CNS, and the data emerging from animal and human studies on the relationship between GH and cognitive function. In this article, particular emphasis is given to the role of GH as a treatment for patients with cognitive impairment resulting from deficiency of the hormone.
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Affiliation(s)
- Fred Nyberg
- Department of Pharmaceutical Biosciences, Uppsala University, PO Box 591, S-751 24 Uppsala, Sweden
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Burnouf S, Martire A, Derisbourg M, Laurent C, Belarbi K, Leboucher A, Fernandez-Gomez FJ, Troquier L, Eddarkaoui S, Grosjean ME, Demeyer D, Muhr-Tailleux A, Buisson A, Sergeant N, Hamdane M, Humez S, Popoli P, Buée L, Blum D. NMDA receptor dysfunction contributes to impaired brain-derived neurotrophic factor-induced facilitation of hippocampal synaptic transmission in a Tau transgenic model. Aging Cell 2013; 12:11-23. [PMID: 23082852 DOI: 10.1111/acel.12018] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/20/2012] [Indexed: 12/24/2022] Open
Abstract
While the spatiotemporal development of Tau pathology has been correlated with occurrence of cognitive deficits in Alzheimer's patients, mechanisms underlying these deficits remain unclear. Both brain-derived neurotrophic factor (BDNF) and its tyrosine kinase receptor TrkB play a critical role in hippocampus-dependent synaptic plasticity and memory. When applied on hippocampal slices, BDNF is able to enhance AMPA receptor-dependent hippocampal basal synaptic transmission through a mechanism involving TrkB and N-methyl-d-Aspartate receptors (NMDAR). Using THY-Tau22 transgenic mice, we demonstrated that hippocampal Tau pathology is associated with loss of synaptic enhancement normally induced by exogenous BDNF. This defective response was concomitant to significant memory impairments. We show here that loss of BDNF response was due to impaired NMDAR function. Indeed, we observed a significant reduction of NMDA-induced field excitatory postsynaptic potential depression in the hippocampus of Tau mice together with a reduced phosphorylation of NR2B at the Y1472, known to be critical for NMDAR function. Interestingly, we found that both NR2B and Src, one of the NR2B main kinases, interact with Tau and are mislocalized to the insoluble protein fraction rich in pathological Tau species. Defective response to BDNF was thus likely related to abnormal interaction of Src and NR2B with Tau in THY-Tau22 animals. These are the first data demonstrating a relationship between Tau pathology and synaptic effects of BDNF and supporting a contribution of defective BDNF response and impaired NMDAR function to the cognitive deficits associated with Tauopathies.
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Affiliation(s)
| | - Alberto Martire
- Department of Therapeutic Research and Medicine Evaluation; Istituto Superiore di Sanità; I-00161; Rome; Italy
| | | | | | | | | | | | | | | | | | | | | | - Alain Buisson
- Grenoble Institute Neurosciences; U836 INSERM; Université J. Fourier; 38042; Grenoble; France
| | | | | | | | - Patrizia Popoli
- Department of Therapeutic Research and Medicine Evaluation; Istituto Superiore di Sanità; I-00161; Rome; Italy
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Zhou X, Zheng F, Moon C, Schlüter OM, Wang H. Bi-directional regulation of CaMKIIα phosphorylation at Thr286 by NMDA receptors in cultured cortical neurons. J Neurochem 2012; 122:295-307. [PMID: 22582824 DOI: 10.1111/j.1471-4159.2012.07787.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The N-methyl-D-aspartate (NMDA) receptor (NMDAR)-stimulated autophosphorylation of calmodulin-dependent kinase IIα at Thr286 may regulate many aspects of neuroplasticity. Here, we show that low NMDA concentration (20 μM) up-regulated Thr286 phosphorylation, and high concentration (100 μM) caused dephosphorylation. We next modulated the strength of NMDAR activation by manipulating NMDAR 2A subunit (NR2A) and NMDAR 2B subunit (NR2B), which represent the major NMDAR subtypes in forebrain regions. Pharmacological inhibition and molecular knockdown of NR2A or NR2B blocked 20 μM NMDA-induced phosphorylation. Conversely, over-expression of NR2A or NR2B enhanced phosphorylation by 20 μM NMDA. The 100 μM NMDA-induced dephosphorylation was suppressed by inhibition or knockdown of NR2A or NR2B, and enhanced by over-expression of NR2A or NR2B. Compared to NR2A, NR2B showed a higher impact on the NMDA-stimulated bi-directional regulation of Thr286 phosphorylation. We further found that activation of NR2A and NR2B by 100 μM NMDA-induced dephosphorylation through protein phosphatases (PP) that are inhibited by high concentration okadaic acid (1 μM), but not by PP2A and PP2B inhibitors. This novel function of NMDAR in dynamic regulation of calmodulin-dependent kinase IIα activity provides new evidence to support the current understanding that, depending on the degree of activation, NMDAR may lead to different and even opposing effects on intracellular signaling.
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Affiliation(s)
- Xianju Zhou
- Department of Physiology, Neuroscience Program, Michigan State University, East Lansing, Michigan, USA
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13
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Geddes AE, Huang XF, Newell KA. Reciprocal signalling between NR2 subunits of the NMDA receptor and neuregulin1 and their role in schizophrenia. Prog Neuropsychopharmacol Biol Psychiatry 2011; 35:896-904. [PMID: 21371516 DOI: 10.1016/j.pnpbp.2011.02.017] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Revised: 02/19/2011] [Accepted: 02/24/2011] [Indexed: 02/01/2023]
Abstract
Schizophrenia is a debilitating neurodevelopmental psychiatric disorder. Both the N-methyl-D-aspartate receptor (NMDAR) and neuregulin1 (NRG1) are key molecules involved in normal brain development that have been linked to schizophrenia pathology and aetiology. The NR2 proteins are critical structural and functional subunits of the NMDAR and are developmentally and spatially regulated. Altered NR2 gene and protein expression has been found in human post-mortem schizophrenia brain tissue together with changes in NRG1 and its receptor ErbB4. The NR2 subunits and ErbB4 share a common anchoring domain on the postsynaptic density and therefore a disruption to either of these molecules may influence the functioning of the other. It has been shown that NRG1 signalling can affect NMDAR levels and function, particularly phosphorylation of the NR2 subunits. However little is known about the possible effects of NMDAR dysfunction on NRG1 signalling, which is important with regards to schizophrenia aetiology as numerous risk factors for the disorder can alter NMDAR functioning during early brain development. This review focuses on the role of the NMDA receptor subunits and NRG1 signalling in schizophrenia and proposes a mechanism by which a disruption to the NMDAR, particularly via altering the balance of NR2 subunits during early development, could influence NRG1 signalling.
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Affiliation(s)
- Amy E Geddes
- Centre for Translational Neuroscience, Illawarra Health and Medical Research Institute, School of Health Sciences, University of Wollongong, Wollongong, NSW 2522, Australia
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Kristiansen LV, Patel SA, Haroutunian V, Meador-Woodruff JH. Expression of the NR2B-NMDA receptor subunit and its Tbr-1/CINAP regulatory proteins in postmortem brain suggest altered receptor processing in schizophrenia. Synapse 2010; 64:495-502. [PMID: 20175224 DOI: 10.1002/syn.20754] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Several lines of evidence implicate aberrant glutamate neurotransmission in the pathophysiology of schizophrenia. In particular, compromised signaling through the N-methyl-D-aspartate (NMDA) receptor has been linked to positive, negative, and cognitive symptoms of this illness. Studies in postmortem brain have identified altered expression of several structural and signaling molecules of the postsynaptic density (PSD), including the abundantly expressed protein PSD-95, which binds directly to NR2 subunits of the NMDA receptor and regulates its trafficking, membrane expression, and downstream signaling. Several mechanisms for functional regulation of the NR2B-containing NMDA receptor, which have been linked to cognitive dysfunction in schizophrenia, are well known. To analyze whether early events in NR2B processing are affected in schizophrenia, we have isolated a subcellular endoplasmic reticulum (ER)-enriched fraction from postmortem brain and analyzed expression of the NR1 and NR2B NMDA receptor subunits as well as PSD-95 in two areas of prefrontal cortex. We found significantly decreased ER expression of NR2B and PSD-95 in dorsolateral prefrontal cortex in schizophrenia. Analysis in total-cell homogenates from the same subjects of NR2B and PSD-95 expression, as well as of the CINAP and Tbr-1 transcription regulatory proteins, indicate that changes in NR2B processing in schizophrenia involve increased ER exit of NR2B containing NMDA receptors.
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Affiliation(s)
- Lars V Kristiansen
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, Alabama, USA.
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15
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Abstract
Previous exposure to a nonlethal ischemic insult protects the brain against subsequent harmful ischemia. N-methyl-D-aspartate (NMDA) receptors are a highly studied target of neuroprotection after ischemia. Recently, NMDA receptor subtypes were implicated in neuronal survival and death. We focused on the contribution of NR2A and cyclic-AMP response element (CRE)-binding protein (CREB) signaling to ischemic tolerance using primary cortical neurons. Ischemia in vitro was modeled by oxygen-glucose deprivation (OGD). Ischemic tolerance was induced by applying 45-mins OGD 24 h before 180-mins OGD. Sublethal OGD also induced cross-tolerance against lethal glutamate and hydrogen peroxide. After sublethal OGD, expression of phosphorylated CREB and CRE transcriptional activity were significantly increased. When CRE activity was inhibited by CREB-S133A, a mutant CREB, ischemic tolerance was abolished. Inhibiting NR2A using NVP-AAM077 attenuated preconditioning-induced neuroprotection and correlated with decreased CRE activity levels. Activating NR2A using bicuculline and 4-aminopiridine induced resistance to lethal ischemia accompanied by elevated CRE activity levels, and this effect was abolished by NVP-AAM077. Elevated brain-derived neurotrophic factor (BDNF) transcriptional activities were observed after sublethal OGD and administration of bicuculline and 4-aminopiridine. NR2A-containing NMDA receptors and CREB signaling have important functions in the induction of ischemic tolerance. This may provide potential novel therapeutic strategies to treat ischemic stroke.
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Biphasic effects of the cholinergic agonist carbachol on long-term potentiation in the dentate gyrus of the mammalian hippocampus. Neurosci Lett 2010; 479:157-60. [DOI: 10.1016/j.neulet.2010.05.056] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2010] [Revised: 04/20/2010] [Accepted: 05/19/2010] [Indexed: 11/21/2022]
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McElligott ZA, Winder DG. Modulation of glutamatergic synaptic transmission in the bed nucleus of the stria terminalis. Prog Neuropsychopharmacol Biol Psychiatry 2009; 33:1329-35. [PMID: 19524008 PMCID: PMC2783684 DOI: 10.1016/j.pnpbp.2009.05.022] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2009] [Revised: 05/12/2009] [Accepted: 05/14/2009] [Indexed: 11/27/2022]
Abstract
Glutamate, catecholamine and neuropeptide signaling within the bed nucleus of the stria terminalis (BNST) have all been identified as key participants in anxiety-like behaviors and behaviors related to withdrawal from exposure to substances of abuse. The BNST is thought to serve as a key relay between limbic cognitive centers and reward, stress and anxiety nuclei. Human studies and animal models have demonstrated that stressors and drugs of abuse can result in long term behavioral modifications that can culminate in psychological diseases such as addiction and post-traumatic stress disorder. The ability of catecholamines and neuropeptides to influence synaptic glutamatergic transmission (stemming from cognitive centers) within the BNST may have profound consequences over these behaviors. In this review we highlight studies examining synaptic plasticity and modulation of excitatory transmission within the BNST, emphasizing how such modulation may result in alterations in anxiety and reward related behavior.
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Affiliation(s)
| | - Danny G. Winder
- Vanderbilt Brain Institute, Vanderbilt University Medical Center, Nashville, TN, USA, Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN, USA, Kennedy Center For Human Development, Vanderbilt University Medical Center, Nashville, TN, USA
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Late phase of long-term potentiation induced by co-application of N-methyl-d-aspartic acid and the antagonist of NR2B-containing N-methyl-d-aspartic acid receptors in rat hippocampus. Neuroscience 2009; 159:127-35. [DOI: 10.1016/j.neuroscience.2008.10.037] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2008] [Revised: 10/06/2008] [Accepted: 10/23/2008] [Indexed: 11/19/2022]
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19
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Rammes G, Starker LK, Haseneder R, Berkmann J, Plack A, Zieglgänsberger W, Ohl F, Kochs EF, Blobner M. Isoflurane anaesthesia reversibly improves cognitive function and long-term potentiation (LTP) via an up-regulation in NMDA receptor 2B subunit expression. Neuropharmacology 2008; 56:626-36. [PMID: 19059421 DOI: 10.1016/j.neuropharm.2008.11.002] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2008] [Revised: 11/03/2008] [Accepted: 11/15/2008] [Indexed: 10/21/2022]
Abstract
Postoperative cognitive dysfunction (POCD) is a decline in cognitive performance after a surgery performed under anaesthesia. The exact roles of surgery and/or anaesthesia for facilitating POCD are unclear. This study investigates the effects of isoflurane anaesthesia on cognitive performance and cellular mechanisms involved in learning and memory function. Male C57BL6/J mice (age: 4-5 months) were anaesthetized with isoflurane in oxygen/air (FiO(2)=0.5) for 2h, non-anaesthetized mice served as controls. After 24h, neurocognitive function, in vitro long-term potentiation (LTP), or protein expression were evaluated. In a visuospatial test, anaesthetized mice showed better cognitive performance as they learned faster compared to controls. In hippocampal slices of anaesthetized mice, in vitro LTP was enhanced as reflected in an increased extracellular field potential (fEPSP) slope after 1h to 210.2+/-17% (control: 156.8+/-7.2%; n=14; p<0.05). NR2B subunits of the NMDA receptors were selectively up-regulated in hippocampal neurones after anaesthesia. Blocking these receptors either with the NR2B selective antagonists ifenprodil or RO25-6981 (R-(R,S)-alpha-(4-hydroxyphenyl)-beta-methyl-4-(phenylmethyl)-1-piperidine propranol), prevents the anaesthesia-induced improvement in cognitive function as well as enhancement of in vitro LTP. The anaesthesia-mediated effects on NR2B subunits were fully reversed to control levels seven days after anaesthesia. The present data suggests that isoflurane anaesthesia induces a hippocampus-specific elevation of NR2B subunit composition, enhances LTP in CA1 neurones, and produces hippocampal-dependent cognitive improvement.
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Affiliation(s)
- Gerhard Rammes
- Department of Anaesthesiology, Technische Universität München, D-81675 Munich, Germany.
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Kollen M, Dutar P, Jouvenceau A. The magnitude of hippocampal long term depression depends on the synaptic location of activated NR2-containing N-methyl-D-aspartate receptors. Neuroscience 2008; 154:1308-17. [PMID: 18538939 DOI: 10.1016/j.neuroscience.2008.04.045] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2008] [Revised: 04/21/2008] [Accepted: 04/22/2008] [Indexed: 10/22/2022]
Abstract
Activation of N-methyl-D-aspartate receptors (NMDARs) is the first step in the induction of certain forms of synaptic plasticity in the hippocampus. In the adult rat hippocampus, NMDARs are composed almost exclusively of NR1 and NR2 subunits with NR1 subunits being mainly associated with either NR2A and/or NR2B subunits. The role played by the different subunits in synaptic plasticity is still controversial. In the present study, we used two different long term depression (LTD) -inducing protocols (electrical and chemical stimulation) to show that activation of NR2A-containing NMDAR subunits leads to the induction of LTD. We also demonstrated that extrasynaptic NR2B-containing NMDARs regulate the magnitude of LTD by exerting a control over the function of synaptic NR2A-containing NMDARs while having no effect on plasticity in the absence of synaptic receptor activation. Taken as a whole, these experiments demonstrate that NMDAR subunits play different roles according to their nature (NR2A or NR2B) and location (synaptic versus extrasynaptic). This sheds new light on the functional role of extrasynaptic NR2B containing-NMDARs. These results are particularly important for a better understanding of certain pathological disorders associated with glutamatergic overactivity.
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Affiliation(s)
- M Kollen
- Faculté de médecine, Centre de Psychiatrie et de Neuroscience U894 INSERM, Université Paris Descartes, Paris, France
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21
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Kash TL, Matthews RT, Winder DG. Alcohol inhibits NR2B-containing NMDA receptors in the ventral bed nucleus of the stria terminalis. Neuropsychopharmacology 2008; 33:1379-90. [PMID: 17625498 PMCID: PMC2864636 DOI: 10.1038/sj.npp.1301504] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Components of the mesolimbic dopamine system, in particular dopaminergic cells in the ventral tegmental area (VTA), have been implicated in the acute reinforcing actions of ethanol. The ventral bed nucleus of the stria terminalis (vBNST) potently regulates dopaminergic cell firing in the VTA, and has been implicated in the behavioral actions of ethanol. The N-methyl-D-asparate receptor (NMDAR) is a major molecular target of ethanol, however, current evidence suggests that ethanol regulation of NMDAR function is widely variable and likely depends on a number of factors. Thus, it is critical to investigate ethanol regulation of NMDAR function at synapses relevant to ethanol-regulated behaviors, such as in the vBNST. Here we show, using multiple techniques, that ethanol inhibits NMDAR function in vBNST neurons in a postsynaptic fashion. Further, we demonstrate the functional presence of both NR2A and NR2B-containing NMDARs in the vBNST. While genetic removal of NR2A did not alter the magnitude of ethanol inhibition, pharmacological blockade of NR2B rendered synaptically activated NMDARs insensitive to ethanol inhibition. Finally, we demonstrate that ethanol inhibits NMDARs in cells in the vBNST that project to the VTA, providing a direct means by which ethanol in the vBNST can modulate the dopaminergic system.
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Affiliation(s)
- Thomas L Kash
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Robert T Matthews
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Danny G Winder
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA
- Center for Molecular Neuroscience, Vanderbilt University School of Medicine, Nashville, TN, USA
- JF Kennedy Center for Research on Human Development, Vanderbilt University School of Medicine, Nashville, TN, USA
- Correspondence: Dr DG Winder, Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, 23rd and Pierce Ave S, Room 724B, RRB, Nashville, TN 37232-0615, USA, Tel: +1 615 322 1144, Fax: +1 615 322 1462,
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Simões P, Silva A, Pereira F, Marques E, Grade S, Milhazes N, Borges F, Ribeiro C, Macedo T. Methamphetamine induces alterations on hippocampal NMDA and AMPA receptor subunit levels and impairs spatial working memory. Neuroscience 2007; 150:433-41. [DOI: 10.1016/j.neuroscience.2007.09.044] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2007] [Revised: 08/28/2007] [Accepted: 09/11/2007] [Indexed: 11/27/2022]
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Fantin M, Marti M, Auberson YP, Morari M. NR2A and NR2B subunit containing NMDA receptors differentially regulate striatal output pathways. J Neurochem 2007; 103:2200-11. [PMID: 17986236 DOI: 10.1111/j.1471-4159.2007.04966.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Triple probe microdialysis was employed to investigate whether striatal NR2A and NR2B subunit containing NMDA receptors regulate the activity of striato-pallidal and striato-nigral projection neurons. Probes were implanted in the striatum, ipsilateral globus pallidus and substantia nigra reticulata. Intrastriatal perfusion with the NR2A subunit selective antagonist (R)-[(S)-1-(4-bromo-phenyl)-ethylamino]-(2,3-dioxo-1,2,3,4-tetrahydroquinoxalin-5-yl)-methyl]-phosphonic acid (NVP-AAM077) reduced pallidal GABA and increased nigral glutamate (GLU) release whereas perfusion with the NR2B subunit selective antagonist (R-(R*,S*)-alpha-(4-hydroxyphenyl)-beta-methyl-4-(phenylmethyl)-1-piperidinepropanol (Ro 25-6981) reduced nigral GABA and elevated striatal and pallidal GLU release. To confirm that changes in GABA levels were because of blockade of (GLUergic-driven) tonic activity of striatofugal neurons, tetrodotoxin was perfused in the striatum. Tetrodotoxin reduced both pallidal and nigral GABA release without changing GLU levels. To investigate whether striatal NR2A and NR2B subunits were also involved in phasic activation of striatofugal neurons, NVP-AAM077 and Ro 25-6981 were challenged against a NMDA concentration able to evoke GABA release in the three areas. Both antagonists prevented the NMDA-induced striatal GABA release. NVP-AAM077 also prevented the NMDA-induced surge in GABA release in the globus pallidus, whereas Ro 25-6981 attenuated it in the substantia nigra. We conclude that striatal NMDA receptors containing NR2A and NR2B subunits preferentially regulate the striato-pallidal and striato-nigral projection neurons, respectively.
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Affiliation(s)
- Martina Fantin
- Department of Experimental and Clinical Medicine, Section of Pharmacology, and Istituto Nazionale di Neuroscience, University of Ferrara, Ferrara, Italy
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25
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Li R, Huang FS, Abbas AK, Wigström H. Role of NMDA receptor subtypes in different forms of NMDA-dependent synaptic plasticity. BMC Neurosci 2007; 8:55. [PMID: 17655746 PMCID: PMC1959237 DOI: 10.1186/1471-2202-8-55] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2007] [Accepted: 07/26/2007] [Indexed: 11/19/2022] Open
Abstract
Background The involvement of different NMDA receptor (NMDAR) subunits has been implicated in several forms of synaptic plasticity. However, it is still controversial to what extent the involvement is specific, and little is known about the role of NMDAR subunits in certain "non-conventional" forms of plasticity. In this study we used subunit-specific blockers to test the roles of NR2A- and NR2B-containing NMDARs in a type of chemical long-term depression (LTD) induced by brief bath application of the NMDAR agonist NMDA to hippocampal slices from 12–18 days old rats. For comparison, we also examined other forms of plasticity, including a "slow LTD" induced by 0.1 Hz stimulation under low Mg2+ conditions as well as long-term potentiation (LTP). Results A blocker of NR2A-containing NMDARs, NVP-AAM077 (NVP), substantially reduced the two forms of studied depression whereas blockers of NR2B-containing NMDARs, Ro25-6981 (Ro) or Ifenprodil (Ife), had no significant effect on them. LTP appeared to be more sensitive as it was fully blocked by NVP and partially blocked by Ro or Ife. However, the blocking effects of NVP could be counteracted by general amplification of NMDA responses by lowering Mg2+ concentration in the perfusion solution. Applying NVP or Ro/Ife on isolated NMDA-EPSPs recorded in low Mg2+ solution reduced responses to about 70% and 20% of initial size, respectively, whereas coapplication of both blockers almost completely abolished the responses. Additionally, NMDA application caused depotentiation of a pathway with prior tetanus-induced LTP, and NVP but not Ro/Ife substantially prevented that depotentiation as well as the chemical LTD of the control pathway. A second tetanus on the LTP pathway induced repotentiation which was fully blocked by NVP but partially blocked by Ro/Ife. Conclusion All of these results on hippocampal slices from young rats can be explained by a simple model, in which NR2A subunits dominate over NR2B subunits with respect to both plasticity and NMDAR-mediated responses. The model suggests that Ca2+ influx into the postsynaptic spine via different subtypes of NMDARs makes up a "final common pathway", controlling synaptic plasticity by its magnitude and temporal pattern regardless of the source.
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Affiliation(s)
- Rui Li
- Department of Medical Biophysics, Institute of Neuroscience and Physiology, Göteborg University, Box 433, 405 30 Göteborg, Sweden
| | - Fen-Sheng Huang
- Department of Medical Biophysics, Institute of Neuroscience and Physiology, Göteborg University, Box 433, 405 30 Göteborg, Sweden
| | - Abdul-Karim Abbas
- Department of Medical Biophysics, Institute of Neuroscience and Physiology, Göteborg University, Box 433, 405 30 Göteborg, Sweden
| | - Holger Wigström
- Department of Medical Biophysics, Institute of Neuroscience and Physiology, Göteborg University, Box 433, 405 30 Göteborg, Sweden
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26
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Sil'kis IG. What are the mechanisms underlying the involvement of different subtypes of NMDA receptors in inducing long-term potentiation and depression in the hippocampus? NEUROSCIENCE AND BEHAVIORAL PHYSIOLOGY 2007; 37:477-80. [PMID: 17505798 DOI: 10.1007/s11055-007-0038-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2005] [Accepted: 02/27/2006] [Indexed: 10/23/2022]
Abstract
It has been hypothesized that the sign (direction) of modification of the efficiency of synaptic transmission depends on the subtype of N-methyl-D-aspartate (NMDA)-sensitive receptors involved. Activation of NMDA receptors with 2A subunits facilitates the induction of long-term potentiation, while receptors with 2B subunits facilitate the induction of long-term depression. However, experimental data have been obtained which contradict this hypothesis. We suggest an alternative hypothesis to explain currently available data. According to this hypothesis, activation of NMDA receptors containing different subunits can lead both to long-term potentiation and long-term depression, depending on the post-tetanic increase in the postsynaptic Ca(2+) concentration relative to the increase induced by preceding stimulation. Activation of NMDA receptors containing 2B subunits can lead to long-term depression of the excitatory input to pyramidal neurons because of the presence of these receptors on inhibitory interneurons, with induction of long-term potentiation on the interneuron and potentiation of inhibitory transmission between interneurons and pyramidal cells.
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Affiliation(s)
- I G Sil'kis
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, Russia.
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27
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Modifications of plastic properties and metaplasticity of glutamatergic synapses in the rat cortex and hippocampus under conditions of reserpine-induced behavioral depression. NEUROPHYSIOLOGY+ 2007. [DOI: 10.1007/s11062-007-0025-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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28
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Wu LJ, Xu H, Ren M, Cao X, Zhuo M. Pharmacological isolation of postsynaptic currents mediated by NR2A- and NR2B-containing NMDA receptors in the anterior cingulate cortex. Mol Pain 2007; 3:11. [PMID: 17470281 PMCID: PMC1871573 DOI: 10.1186/1744-8069-3-11] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2007] [Accepted: 04/30/2007] [Indexed: 11/10/2022] Open
Abstract
NMDA receptors (NMDARs) are involved in excitatory synaptic transmission and plasticity associated with a variety of brain functions, from memory formation to chronic pain. Subunit-selective antagonists for NMDARs provide powerful tools to dissect NMDAR functions in neuronal activities. Recently developed antagonist for NR2A-containing receptors, NVP-AAM007, triggered debates on its selectivity and involvement of the NMDAR subunits in bi-directional synaptic plasticity. Here, we re-examined the pharmacological properties of NMDARs in the anterior cingulate cortex (ACC) using NVP-AAM007 as well as ifenprodil, a selective antagonist for NR2B-containing NMDARs. By alternating sequence of drug application and examining different concentrations of NVP-AAM007, we found that the presence of NVP-AAM007 did not significantly affect the effect of ifenprodil on NMDAR-mediated EPSCs. These results suggest that NVP-AAM007 shows great preference for NR2A subunit and could be used as a selective antagonist for NR2A-containing NMDARs in the ACC.
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Affiliation(s)
- Long-Jun Wu
- Department of Physiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Medical Science Building, Room 3342, Toronto, Canada
| | - Hui Xu
- Department of Physiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Medical Science Building, Room 3342, Toronto, Canada
| | - Ming Ren
- Department of Physiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Medical Science Building, Room 3342, Toronto, Canada
| | - Xiaoyan Cao
- Department of Physiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Medical Science Building, Room 3342, Toronto, Canada
| | - Min Zhuo
- Department of Physiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Medical Science Building, Room 3342, Toronto, Canada
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29
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Liu Y, Wong TP, Aarts M, Rooyakkers A, Liu L, Lai TW, Wu DC, Lu J, Tymianski M, Craig AM, Wang YT. NMDA receptor subunits have differential roles in mediating excitotoxic neuronal death both in vitro and in vivo. J Neurosci 2007; 27:2846-57. [PMID: 17360906 PMCID: PMC6672582 DOI: 10.1523/jneurosci.0116-07.2007] [Citation(s) in RCA: 586] [Impact Index Per Article: 34.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Well-documented experimental evidence from both in vitro and in vivo models of stroke strongly supports the critical involvement of NMDA receptor-mediated excitotoxicity in neuronal damage after stroke. Despite this, the results of clinical trials testing NMDA receptor antagonists as neuroprotectants after stroke and brain trauma have been discouraging. Here, we report that in mature cortical cultures, activation of either synaptic or extrasynaptic NR2B-containing NMDA receptors results in excitotoxicity, increasing neuronal apoptosis. In contrast, activation of either synaptic or extrasynaptic NR2A-containing NMDA receptors promotes neuronal survival and exerts a neuroprotective action against both NMDA receptor-mediated and non-NMDA receptor-mediated neuronal damage. A similar opposing action of NR2B and NR2A in mediating cell death and cell survival was also observed in an in vivo rat model of focal ischemic stroke. Moreover, we found that blocking NR2B-mediated cell death was effective in reducing infarct volume only when the receptor antagonist was given before the onset of stroke and not 4.5 h after stroke. In great contrast, activation of NR2A-mediated cell survival signaling with administration of either glycine alone or in the presence of NR2B antagonist significantly attenuated ischemic brain damage even when delivered 4.5 h after stroke onset. Together, the present work provides a molecular basis for the dual roles of NMDA receptors in promoting neuronal survival and mediating neuronal damage and suggests that selective enhancement of NR2A-containing NMDA receptor activation with glycine may constitute a promising therapy for stroke.
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Affiliation(s)
- Yitao Liu
- Brain Research Centre, Vancouver Coastal Health Research Institute and University of British Columbia, Vancouver, British Columbia, Canada V6T 2B5, and
| | - Tak Pan Wong
- Brain Research Centre, Vancouver Coastal Health Research Institute and University of British Columbia, Vancouver, British Columbia, Canada V6T 2B5, and
| | - Michelle Aarts
- Toronto Western Hospital Research Institute, Toronto, Ontario, Canada M5T 2S8
| | - Amanda Rooyakkers
- Brain Research Centre, Vancouver Coastal Health Research Institute and University of British Columbia, Vancouver, British Columbia, Canada V6T 2B5, and
| | - Lidong Liu
- Brain Research Centre, Vancouver Coastal Health Research Institute and University of British Columbia, Vancouver, British Columbia, Canada V6T 2B5, and
| | - Ted Weita Lai
- Brain Research Centre, Vancouver Coastal Health Research Institute and University of British Columbia, Vancouver, British Columbia, Canada V6T 2B5, and
| | - Dong Chuan Wu
- Brain Research Centre, Vancouver Coastal Health Research Institute and University of British Columbia, Vancouver, British Columbia, Canada V6T 2B5, and
| | - Jie Lu
- Brain Research Centre, Vancouver Coastal Health Research Institute and University of British Columbia, Vancouver, British Columbia, Canada V6T 2B5, and
| | - Michael Tymianski
- Toronto Western Hospital Research Institute, Toronto, Ontario, Canada M5T 2S8
| | - Ann Marie Craig
- Brain Research Centre, Vancouver Coastal Health Research Institute and University of British Columbia, Vancouver, British Columbia, Canada V6T 2B5, and
| | - Yu Tian Wang
- Brain Research Centre, Vancouver Coastal Health Research Institute and University of British Columbia, Vancouver, British Columbia, Canada V6T 2B5, and
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Alzoubi KH, Aleisa AM, Alkadhi KA. Adult-onset hypothyroidism facilitates and enhances LTD: Reversal by chronic nicotine treatment. Neurobiol Dis 2007; 26:264-72. [PMID: 17331737 DOI: 10.1016/j.nbd.2007.01.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2006] [Revised: 11/28/2006] [Accepted: 01/12/2007] [Indexed: 11/21/2022] Open
Abstract
Chronic nicotine treatment reverses hypothyroidism-induced impairment of hippocampus-dependent spatial memory and long-term potentiation (LTP). We investigated the effect of hypothyroidism on long-term depression (LTD) and possible protection by nicotine. Following paired pulse stimulation, LTD was expressed in hippocampal area CA1 of anesthetized thyroidectomized, euthyroid (sham control), nicotine-treated and nicotine-treated thyroidectomized (hypothyroid) rats. In hypothyroid rats, a significantly higher LTD magnitude was seen compared with that in control rats. A brief train of stimuli (5 pulses at 100 Hz), which did not affect synaptic transmission in control rats, induced a robust LTD in hypothyroid rats suggesting facilitation of LTD expression in these rats. Chronic nicotine treatment (1 mg/kg, 2x day) of hypothyroid rats reversed hypothyroidism-induced enhancement and facilitation of LTD. Western blot analysis of the NMDA receptor subunits in the membranous fractions of hippocampal area CA1 neurons revealed that hypothyroidism reduced NR1 and increased NR2B without affecting NR2A protein levels. These changes in NMDA receptors in hypothyroid rats were reversed by chronic nicotine treatment. Hypothyroidism did not alter BDNF or nicotinic acetylcholine receptor (nAChR) levels. However, nicotine treatment increased protein levels of these molecules in both euthyroid and hypothyroid rats. Our results suggest that alterations in the levels of NMDA receptor subunits may account for the facilitation and enhancement of LTD in hypothyroidism.
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Affiliation(s)
- K H Alzoubi
- Department of Clinical Pharmacy, College of Pharmacy, Jordan University of Science and Technology, Irbid, Jordan
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31
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Gerkin RC, Lau PM, Nauen DW, Wang YT, Bi GQ. Modular competition driven by NMDA receptor subtypes in spike-timing-dependent plasticity. J Neurophysiol 2007; 97:2851-62. [PMID: 17267756 DOI: 10.1152/jn.00860.2006] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
N-methyl-d-aspartate receptors (NMDARs) play a critical role in transducing neuronal activity patterns into changes in synaptic strength. However, how they mediate this transduction in response to physiological stimuli has remained elusive. In particular, it has been debated whether different NMDAR subtypes play opposing signaling roles in synaptic plasticity. Using perforated patch-clamp recordings from pairs of synaptically connected glutamatergic neurons in dissociated hippocampal culture, we found that spike-timing-dependent potentiation induced by pairing pre- and postsynaptic spikes required the activation of a fast component of NMDAR current that is likely to be mediated by NR2A-containing NMDARs (NR2A-NRs). In contrast, spike-timing-dependent depression required a slow component of NMDAR current carried by NR2B-containing NMDARs (NR2B-NRs). CV analysis showed that the locus of this depression was primarily presynaptic in pairs of cells making strong synaptic connections, whereas weaker synapses showed no clear preference for pre- or postsynaptic expression. This depression was not significantly reduced by antagonism of the CB1 receptor, in contrast to spike-timing-dependent depression in the neocortex that requires presynaptic CB1 signaling. With blockade of NR2B-NRs, spike triplets that contained both potentiating and depressing spike-timing components induced net potentiation. However, when the putative NR2A-NR population is inhibited, these spike triplets resulted in either depression or no net change, depending on the temporal order of the spike-timing components. These results imply a dynamic competition between signaling modules that can be biased by differentially antagonizing NMDAR subtypes during the induction of spike-timing-dependent plasticity. Using a simple model, we show that such a modular competition recapitulates our observations.
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Affiliation(s)
- Richard C Gerkin
- Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA
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32
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Bartlett TE, Bannister NJ, Collett VJ, Dargan SL, Massey PV, Bortolotto ZA, Fitzjohn SM, Bashir ZI, Collingridge GL, Lodge D. Differential roles of NR2A and NR2B-containing NMDA receptors in LTP and LTD in the CA1 region of two-week old rat hippocampus. Neuropharmacology 2007; 52:60-70. [PMID: 16904707 DOI: 10.1016/j.neuropharm.2006.07.013] [Citation(s) in RCA: 201] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2006] [Revised: 07/05/2006] [Accepted: 07/06/2006] [Indexed: 10/24/2022]
Abstract
The role of NMDA receptors in the induction of long-term potentiation (LTP) and long-term depression (LTD) is well established but which particular NR2 subunits are involved in these plasticity processes is still a matter of controversy. We have studied the effects of subtype selective NMDA receptor antagonists on LTP induced by high frequency stimulation (100 Hz for 1s) and LTD induced by low frequency stimulation (1 Hz for 15 min) in the CA1 region of hippocampal slices from 14 day old Wistar rats. Against recombinant receptors in HEK293 cells NVP-AAM077 (NVP) was approximately 14-fold selective for NR2A vs NR2B receptors, whilst Ro 25-6981 (Ro) was highly selective for NR2B receptors. On NMDA receptor-mediated EPSCs from Schaffer collaterals in CA1 neurones, NVP and Ro both reduced the amplitude but differentially affected the time constant of decay. The data are compatible with the selective effect of NVP (0.1 microM) and Ro (4 microM) on native NR2A and NBR2B receptors, respectively. NVP reduced both LTP and LTD whereas Ro reduced only LTP. Thus, LTP was reduced by 63% at 0.1 microM NVP and almost completely at 0.4 microM whereas 5 microM Ro reduced LTP by 45%. These data are consistent with a role for both NR2A and NR2B in the induction of LTP, under our experimental conditions. In comparison, LTD was unaffected by Ro (5 microM) even in the presence of a glutamate uptake inhibitor threo-beta-benzylaspartic acid (TBOA) to increase the concentration of glutamate at NR2B containing receptors. NVP (0.2-0.4 microM), however, produced a concentration dependent inhibition of LTD which was complete at 0.4 microM. The lack of effect of 0.1 microM NVP on LTD contrasts with its marked effect on LTP and raises the possibility that different NVP-sensitive NR2 subunit-containing NMDA receptors are required for LTP and LTD in this preparation.
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Affiliation(s)
- Thomas E Bartlett
- MRC Centre for Synaptic Plasticity, Department of Anatomy, University of Bristol, School of Medical Sciences, University Walk, Bristol, BS8 1TD, UK
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Li GQ, Su WK, Yao ZJ. An Efficient Synthesis of Selective Human NR2A Antagonist NVP-AAM077. CHINESE J CHEM 2006. [DOI: 10.1002/cjoc.200690333] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Smith CC, McMahon LL. Estradiol-induced increase in the magnitude of long-term potentiation is prevented by blocking NR2B-containing receptors. J Neurosci 2006; 26:8517-22. [PMID: 16914677 PMCID: PMC6674362 DOI: 10.1523/jneurosci.5279-05.2006] [Citation(s) in RCA: 161] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Estradiol, through activation of genomic estrogen receptors, induces changes in synaptic morphology and function in hippocampus, a brain region important for memory acquisition. Specifically, this hormone increases CA1 pyramidal cell dendritic spine density, NMDA receptor (NMDAR)-mediated transmission, and the magnitude of long-term potentiation (LTP) at CA3-CA1 synapses. We recently reported that the estradiol-induced increase in LTP magnitude occurs only when there is a simultaneous increase in the fractional contribution of NMDAR-mediated transmission relative to AMPA receptor transmission, suggesting a direct role for the increase in NMDAR transmission to the heightened LTP magnitude. Estradiol has been shown to increase expression of the NMDAR subunit NR2B, but whether this translates into an increase in function of NR2B-containing receptors remains to be determined. Here we show that not only is the estradiol-induced increase in NMDAR transmission mediated by NR2B-containing receptors, but blocking these receptors using RO25-6981 [R-(R,S)-alpha-(4-hydroxyphenyl)-beta-methyl-4-(phenylmethyl)-1-piperidine propranol] (0.5 microM), an NR2B selective antagonist, prevents the estradiol-induced increase in LTP magnitude. Thus, our data show a causal link between the estradiol-induced increase in transmission mediated by NR2B-containing NMDARs and the increase in LTP magnitude.
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35
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Frizelle PA, Chen PE, Wyllie DJA. Equilibrium Constants for (R)-[(S)-1-(4-Bromo-phenyl)-ethylamino]-(2,3-dioxo-1,2,3,4-tetrahydroquinoxalin-5-yl)-methyl]-phosphonic Acid (NVP-AAM077) Acting at Recombinant NR1/NR2A and NR1/NR2BN-Methyl-d-aspartate Receptors: Implications for Studies of Synaptic Transmission. Mol Pharmacol 2006; 70:1022-32. [PMID: 16778008 DOI: 10.1124/mol.106.024042] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We have quantified the effects of the N-methyl-d-aspartate (NMDA) receptor antagonist (R)-[(S)-1-(4-bromo-phenyl)-ethylamino]-(2,3-dioxo-1,2,3,4-tetrahydroquinoxalin-5-yl)-methyl]-phosphonic acid (NVP-AAM077) at rat recombinant N-methyl-D-aspartate receptor (NR)1/NR2A and NR1/NR2B NMDA receptors expressed in Xenopus laevis oocytes. We observed no difference in the steady-state levels of inhibition produced by NVP-AAM077 when it was either preapplied or coapplied with glutamate. The IC50 values for NVP-AAM077 acting at NR1/NR2A NMDA receptors were, as expected, dependent on the glutamate concentration used to evoke responses, being 31 +/- 2 nM (with glutamate at its EC50 concentration) and 214 +/- 10 nM (at 10 times the EC50 concentration). Schild analysis confirmed that the antagonism produced by NVP-AAM077 at NR1/NR2A NMDA receptors was competitive and gave an estimate of its equilibrium constant (K(B)) of 15 +/- 2 nM. Furthermore, Schild analysis of an NMDA receptor carrying a threonine-to-alanine point mutation in the NR2A ligand binding site indicated that NVP-AAM077 still acted in a competitive manner but with its K(B) increased by around 15-fold. At NR1/NR2B NMDA receptors, NVP-AAM077 displayed reduced potency. An IC50 value of 215 +/- 13 nM was obtained in the presence of the EC50 concentration of glutamate (1.5 microM), whereas a value of 2.2 +/- 0.14 microM was obtained with higher (15 microM) glutamate concentrations. Schild analysis gave a K(B) for NVP-AAM077 at NR2B-containing receptors of 78 +/- 3 nM. Finally, using a kinetic scheme to model "synaptic-like" activation of NMDA receptors, we show that the difference in the equilibrium constants for NVP-AAM077 is not sufficient to discriminate between NR2A-containing or NR2B-containing NMDA receptors.
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Affiliation(s)
- Pamela A Frizelle
- Centre for Neuroscience Research, University of Edinburgh, 1 George Square, Edinburgh EH8 9JZ, UK
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36
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Clarke RJ, Johnson JW. NMDA receptor NR2 subunit dependence of the slow component of magnesium unblock. J Neurosci 2006; 26:5825-34. [PMID: 16723541 PMCID: PMC6675262 DOI: 10.1523/jneurosci.0577-06.2006] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
NMDA receptor activity is important for many physiological functions, including synapse formation and alterations in synaptic strength. NMDA receptors are composed most commonly of NR1 and NR2 subunits. There are four NR2 subunits (NR2A-NR2D). NR2 subunit expression varies across both brain regions and developmental stages. The identity of the NR2 subunit within a functional NMDA receptor helps to determine many pharmacological and biophysical receptor properties, including strength of block by external Mg2+ (Mg(o)2+). Mg(o)2+ block confers strong voltage dependence to NMDA receptor-mediated responses and is critically important for many of the functions that the NMDA receptor plays within the CNS. Here we describe the NR2 subunit dependence of the kinetics of Mg(o)2+ unblock after rapid depolarizations. We find that Mg(o)2+ unblocks from NR1/2A and NR1/2B receptors with a prominent slow component similar to that previously described in native hippocampal and cortical NMDA receptors. Strikingly, this slow component of Mg(o)2+ unblock is completely absent from NR1/2C and NR1/2D receptors. Thus currents from NR1/2C and NR1/2D receptors respond more rapidly to fast depolarizations than currents from NR1/2A and NR1/2B receptors. In addition, the slow component of Mg(o)2+ unblock from NR1/2B receptors is consistently slower than from NR1/2A receptors. This makes rapid depolarizations, such as action potential waveforms, more efficacious at stimulating Mg(o)2+ unblock from NR1/2A than from NR1/2B receptors. These NR2 subunit differences in the kinetics of Mg(o)2+ unblock are likely to help determine the contribution of each NMDA receptor subtype to current flow during synaptic activity.
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37
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Weitlauf C, Honse Y, Auberson YP, Mishina M, Lovinger DM, Winder DG. Activation of NR2A-containing NMDA receptors is not obligatory for NMDA receptor-dependent long-term potentiation. J Neurosci 2006; 25:8386-90. [PMID: 16162920 PMCID: PMC6725680 DOI: 10.1523/jneurosci.2388-05.2005] [Citation(s) in RCA: 142] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Activation of NMDA receptors (NMDARs) within the CNS represents a major signal for persistent alterations in glutamatergic signaling, such as long-term potentiation (LTP) and long-term depression. NMDARs are composed of a combination of NR1 and NR2 subunits, with distinct NR2 subunits imparting distinct characteristics on the receptor. One particular NR2 subunit, NR2A (NRepsilon1), has been proposed to play an integral role in LTP induction in the hippocampus and cortex. Here, we report studies investigating the role of NR2A in LTP induction in the dorsolateral bed nucleus of the stria terminalis (dlBNST). The putative NR2A-specific inhibitor NVP-AAM077 (AAM077) has been used previously to demonstrate the dependence of cortical and hippocampal LTP on NMDARs containing NR2A subunits. We report here the same sensitivity of LTP to pretreatment with AAM077 (0.4 microm) in the dlBNST. However, inconsistent with the conclusion that LTP in the dlBNST is NR2A dependent, we see intact LTP in the dlBNST of NR2A knock-out mice. Because we also see blockade of this dlBNST LTP in NR2A knock-out mice after pretreatment with AAM077, we conclude that the antagonist is targeting non-NR2A subunit-containing receptors. Using a variety of cultured cell types, we find that AAM077 (0.4 microm) can attenuate transmission of NR2B subunit-containing NMDARs when preapplied rather than coapplied with an agonist. Therefore, we conclude that NR2A is not obligatory for the induction of LTP in the dlBNST. Furthermore, our data demonstrate that care must be exercised in the interpretation of data generated with AAM077 when the compound is applied before an agonist.
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Affiliation(s)
- Carl Weitlauf
- Center for Molecular Neuroscience, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0615, USA
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38
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Jouvenceau A, Dutar P. A role for the protein phosphatase 2B in altered hippocampal synaptic plasticity in the aged rat. ACTA ACUST UNITED AC 2006; 99:154-61. [PMID: 16442785 DOI: 10.1016/j.jphysparis.2005.12.009] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Synaptic plasticity following NMDA application on hippocampal slices from young (3-5 months) and aged (24-27 months) rats was compared. In young rats, NMDA (20 microM) induced opposite effects depending on the duration of the application. A short (1 min) or long (5 min) application induced a long-term depression of synaptic activity while a 3 min application induced a potentiation. In aged rats, however, NMDA application always induced depression, regardless of the duration. To identify mechanisms which could explain the difference observed between young and aged rats, we explored changes in NMDA receptor activation and changes in kinase/phosphatase balance. We first demonstrate that the potentiation present in slices from young rats was not restored in aged rats by exogenous application of the co-agonist of NMDA receptor d-serine (which compensates for the changes in NMDAR activation seen in aged rats). This suggested that alterations in synaptic plasticity activation mainly involve intracellular mechanisms. We next showed that the participation of the kinases PKA and CaMKII in the NMDA-induced potentiation in young rats is negligible. Finally, we determined the consequences of phosphatase inhibition in aged rats. Incubation of slices in okadaic acid (a PP1/PP2B antagonist) did not affect the depression induced by a 3min NMDA application in aged rats. The PP2B antagonist FK506 restored potentiation in aged rats (3 min NMDA application). In hippocampal neurons from aged rats, a depression is always observed, suggesting a preferential activation of PP2B by NMDA in these neurons.
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Affiliation(s)
- Anne Jouvenceau
- INSERM U549, Neurobiologie de la croissance et de la sénescence, 2 ter rue d'Alésia, 75014 Paris, France.
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39
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40
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Zhong WX, Dong ZF, Tian M, Cao J, Xu L, Luo JH. N-methyl-d-aspartate receptor-dependent long-term potentiation in CA1 region affects synaptic expression of glutamate receptor subunits and associated proteins in the whole hippocampus. Neuroscience 2006; 141:1399-413. [PMID: 16766131 DOI: 10.1016/j.neuroscience.2006.04.070] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2006] [Revised: 03/12/2006] [Accepted: 04/28/2006] [Indexed: 11/29/2022]
Abstract
Long term potentiation in hippocampus, evoked by high-frequency stimulation, is mediated by two major glutamate receptor subtypes, alpha-amino-3-hydroxyl-5-methyl-4-isoxazole propionate receptors and N-methyl-D-aspartate receptors. Receptor subunit composition and its interaction with cytoplasmic proteins constitute different pathways regulating synaptic plasticity. Here, we provide further evidence that N-methyl-D-aspartate receptor-mediated long term potentiation evoked at hippocampal CA1 region of rats induced by high-frequency stimulation of the Schaffer collateral-commissural pathway in vivo is not dependent on N-methyl-D-aspartate receptor subunit NR2B. Applying semi-quantitative immunoblotting, we found that in the whole tetanized hippocampus, synaptic expression of the N-methyl-D-aspartate and alpha-amino-3-hydroxyl-5-methyl-4-isoxazole propionate receptor subunits (NR1, NR2A, glutamate receptor 1) and their associated partners, e.g. synaptic associated protein 97, postsynaptic density protein 95, alpha subunit of Ca2+/calmodulin-dependent protein kinase II, neuronal nitricoxide synthase, increased 180 min post-high-frequency stimulation. Moreover, phosphorylation of Ca2+/calmodulin-dependent protein kinase II at thr286 and glutamate receptor 1 at ser831 was increased 30 min post-high-frequency stimulation and blocked by N-methyl-D-aspartate receptor antagonists (AP-5 and MK-801). In sham group and controls, these changes were not observed. The expression of several other synaptic proteins (NR2B, glutamate receptors 2/3, N-ethylmaleimide sensitive factor) was not affected by long term potentiation induction. In hippocampal homogenates, the level of these proteins remained unchanged. These data indicate that N-methyl-D-aspartate receptor-dependent long term potentiation in CA1 region in vivo mainly affects the synaptic expression of glutamate receptor subunits and associated proteins in the whole hippocampus. The alteration of molecular aspects can play a role in regulating the long-lasting synaptic modification in hippocampal long term potentiation in vivo.
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Affiliation(s)
- W X Zhong
- Department of Neurobiology, Zhejiang University School of Medicine, 353 Yanan Road, Hangzhou 310006, PR China
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41
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Izumi Y, Nagashima K, Murayama K, Zorumski CF. Acute effects of ethanol on hippocampal long-term potentiation and long-term depression are mediated by different mechanisms. Neuroscience 2005; 136:509-17. [PMID: 16216426 DOI: 10.1016/j.neuroscience.2005.08.002] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2005] [Revised: 07/22/2005] [Accepted: 08/01/2005] [Indexed: 12/26/2022]
Abstract
To determine potential mechanisms contributing to ethanol-induced cognitive impairment, we examined acute effects of ethanol on hippocampal N-methyl-d-aspartate receptors and forms of synaptic plasticity thought to underlie memory processing. In the CA1 region of rat hippocampal slices, ethanol partially inhibited N-methyl-d-aspartate receptor-mediated synaptic responses at concentrations up to 180 mM. The block of synaptic N-methyl-d-aspartate receptors by 60mM ethanol occluded the effects of 10 microM ifenprodil, an agent that has relative selectivity for N-methyl-D-aspartate receptors expressing NR1 and NR2B subunits. Ethanol did not occlude the effects of a low concentration of 2-amino-5-phosphonovalerate, an antagonist with less N-methyl-d-aspartate receptor subtype selectivity. Recent studies indicate that ifenprodil and other NR2B-selective antagonists inhibit N-methyl-D-aspartate receptor-dependent long-term depression but not long-term potentiation. We found that ethanol reversibly inhibited long-term depression in a manner consistent with its effects on synaptic N-methyl-D-aspartate receptors. Ethanol also inhibited the induction of N-methyl-D-aspartate receptor-dependent long-term potentiation, but the actions on long-term potentiation were complex and largely irreversible over the time course of our experiments. Furthermore, ethanol inhibited a form of long-term potentiation induced by very high frequency stimulation that does not depend on N-methyl-D-aspartate receptor activation. The effects of ethanol on both forms of long-term potentiation, but not on long-term depression, were at least partially reversed by block of GABA type A receptors with picrotoxin. These results indicate that pharmacologically relevant concentrations of ethanol exert preferential effects on a subtype of synaptic N-methyl-D-aspartate receptors in the CA1 hippocampal region. Inhibition of synaptic N-methyl-D-aspartate receptors appears to contribute strongly to ethanol-mediated long-term depression inhibition, but effects on long-term potentiation are complex, involving, at least partially, changes in GABAergic transmission.
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Affiliation(s)
- Y Izumi
- Department of Psychiatry, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA
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42
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Zhao MG, Toyoda H, Lee YS, Wu LJ, Ko SW, Zhang XH, Jia Y, Shum F, Xu H, Li BM, Kaang BK, Zhuo M. Roles of NMDA NR2B Subtype Receptor in Prefrontal Long-Term Potentiation and Contextual Fear Memory. Neuron 2005; 47:859-72. [PMID: 16157280 DOI: 10.1016/j.neuron.2005.08.014] [Citation(s) in RCA: 393] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2005] [Revised: 06/17/2005] [Accepted: 08/10/2005] [Indexed: 10/25/2022]
Abstract
Cortical plasticity is thought to be important for the establishment, consolidation, and retrieval of permanent memory. Hippocampal long-term potentiation (LTP), a cellular mechanism of learning and memory, requires the activation of glutamate N-methyl-D-aspartate (NMDA) receptors. In particular, it has been suggested that NR2A-containing NMDA receptors are involved in LTP induction, whereas NR2B-containing receptors are involved in LTD induction in the hippocampus. However, LTP in the prefrontal cortex is less well characterized than in the hippocampus. Here we report that the activation of the NR2B and NR2A subunits of the NMDA receptor is critical for the induction of cingulate LTP, regardless of the induction protocol. Furthermore, pharmacological or genetic blockade of the NR2B subunit in the cingulate cortex impaired the formation of early contextual fear memory. Our results demonstrate that the NR2B subunit of the NMDA receptor in the prefrontal cortex is critically involved in both LTP and contextual memory.
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Affiliation(s)
- Ming-Gao Zhao
- Laboratory of Higher Brain Functions, Institute of Neurobiology, Fudan University, 220 Han-Dan Road, Shanghai 200433, China
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43
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Waxman EA, Lynch DR. N-methyl-D-aspartate receptor subtype mediated bidirectional control of p38 mitogen-activated protein kinase. J Biol Chem 2005; 280:29322-33. [PMID: 15967799 DOI: 10.1074/jbc.m502080200] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
N-methyl-d-aspartate receptor (NMDAR) stimulation activates many downstream mechanisms involved in both cell survival and cell death. The manner in which the NMDAR regulates one of these pathways, the p38 mitogen-activated protein kinase (p38) pathway, is currently unknown. In the present study, we have defined a developmental-, concentration-, and time-dependent phosphorylation and subsequent dephosphorylation of p38. In cultured hippocampal neurons 7-8 days in vitro (DIV7-8), NMDAR stimulation leads to a concentration-dependent increase in p38 phosphorylation (phospho-p38). However, in more mature neurons (>DIV17) application of NMDA produces concentration-dependent effects, such that low concentrations result in sustained increases in phospho-p38 levels, and high concentrations dephosphorylate p38 within 5 min. Conantokin G, an antagonist of NR1/2A/2B and NR1/2B receptors, inhibits p38 phosphorylation, while NR1/2B-specific antagonists prevent the rapid dephosphorylation of p38 without affecting p38 activation. Furthermore, inhibition of calcineurin prevents the activation of p38, whereas inhibition of phosphoinositide 3-kinase (PI3K) prevents the rapid dephosphorylation of p38. Our results support the presence of subtype-dependent pathways regulating p38 activation and deactivation: one involves NR1/2A/2B receptors activating calcineurin and resulting in p38 phosphorylation, and the other utilizes NR1/2B receptors binding to and activating PI3K and leading to the dephosphorylation of p38 in a manner involving both NR1/2A/2B receptor activation and tyrosine phosphorylation of NR2B. The ability of NMDAR subtype-specific mechanisms to regulate p38 has implications for NMDAR-mediated synaptic plasticity, gene regulation, and excitotoxicity.
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Affiliation(s)
- Elisa A Waxman
- Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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