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Sample records for nmda receptor subunits

  1. Subunit Arrangement and Function in NMDA Receptors

    SciTech Connect

    Furukawa,H.; Singh, S.; Mancusso, R.; Gouaux, E.

    2005-01-01

    Excitatory neurotransmission mediated by NMDA (N-methyl-D-aspartate) receptors is fundamental to the physiology of the mammalian central nervous system. These receptors are heteromeric ion channels that for activation require binding of glycine and glutamate to the NR1 and NR2 subunits, respectively. NMDA receptor function is characterized by slow channel opening and deactivation, and the resulting influx of cations initiates signal transduction cascades that are crucial to higher functions including learning and memory. Here we report crystal structures of the ligand-binding core of NR2A with glutamate and that of the NR1-NR2A heterodimer with glutamate and glycine. The NR2A-glutamate complex defines the determinants of glutamate and NMDA recognition, and the NR1-NR2A heterodimer suggests a mechanism for ligand-induced ion channel opening. Analysis of the heterodimer interface, together with biochemical and electrophysiological experiments, confirms that the NR1-NR2A heterodimer is the functional unit in tetrameric NMDA receptors and that tyrosine 535 of NR1, located in the subunit interface, modulates the rate of ion channel deactivation.

  2. The receptor subunits generating NMDA receptor mediated currents in oligodendrocytes

    PubMed Central

    Burzomato, Valeria; Frugier, Guillaume; Pérez-Otaño, Isabel; Kittler, Josef T; Attwell, David

    2010-01-01

    NMDA receptors have been shown to contribute to glutamate-evoked currents in oligodendrocytes. Activation of these receptors damages myelin in ischaemia, in part because they are more weakly blocked by Mg2+ than are most neuronal NMDA receptors. This weak Mg2+ block was suggested to reflect an unusual subunit composition including the NR2C and NR3A subunits. Here we expressed NR1/NR2C and triplet NR1/NR2C/NR3A recombinant receptors in HEK cells and compared their currents with those of NMDA-evoked currents in rat cerebellar oligodendrocytes. NR1/NR2C/3A receptors were less blocked by 2 mm Mg2+ than were NR1/NR2C receptors (the remaining current was 30% and 18%, respectively, of that seen without added Mg2+) and showed less channel noise, suggesting a smaller single channel conductance. NMDA-evoked currents in oligodendrocytes showed a Mg2+ block (to 32%) similar to that observed for NR1/NR2C/NR3A and significantly different from that for NR1/NR2C receptors. Co-immunoprecipitation revealed interactions between NR1, NR2C and NR3A subunits in a purified myelin preparation from rat brain. These data are consistent with NMDA-evoked currents in oligodendrocytes reflecting the activation of receptors containing NR1, NR2C and NR3A subunits. PMID:20660562

  3. NMDA receptor structures reveal subunit arrangement and pore architecture

    PubMed Central

    Lee, Chia-Hsueh; Lü, Wei; Michel, Jennifer Carlisle; Goehring, April; Du, Juan; Song, Xianqiang; Gouaux, Eric

    2014-01-01

    Summary N-methyl-d-aspartate (NMDA) receptors are Hebbian-like coincidence detectors, requiring binding of glycine and glutamate in combination with the relief of voltage-dependent magnesium block to open an ion conductive pore across the membrane bilayer. Despite the importance of the NMDA receptor in the development and function of the brain, a molecular structure of an intact receptor has remained elusive. Here we present x-ray crystal structures of the GluN1/GluN2B NMDA receptor with the allosteric inhibitor, Ro25-6981, partial agonists and the ion channel blocker, MK-801. Receptor subunits are arranged in a 1-2-1-2 fashion, demonstrating extensive interactions between the amino terminal and ligand binding domains. The transmembrane domains harbor a closed-blocked ion channel, a pyramidal central vestibule lined by residues implicated in binding ion channel blockers and magnesium, and a ~2-fold symmetric arrangement of ion channel pore loops. These structures provide new insights into the architecture, allosteric coupling and ion channel function of NMDA receptors. PMID:25008524

  4. NR2C and NR2D subunits of NMDA receptors in frog and turtle retina.

    PubMed

    Vitanova, Lily Alexandrova

    2012-12-01

    Glutamate NMDA (N-methyl-D-aspartate) receptors are widely distributed in the central nervous system where they are involved in cognitive processes, motor control and many other functions. They are also well studied in the retina, which may be regarded as a biological model of the nervous system. However, little is known about NR2C and NR2D subunits of NMDA receptors, which have some specific features as compared to other subunits. Consequently the aim of the present study was to investigate their distribution in frog (Rana ridibunda) and turtle (Emys orbicularis) retinas which possess mixed and cone types of retina respectively. The experiments were performed using an indirect immunofluorescence method. Four antibodies directed to NR2C and NR2D subunits of NMDA receptor, as well as three antibodies directed to different splice variants of NR1 subunit, which is known to be obligatory for proper functioning of the receptor, were applied. All antibodies caused well expressed labeling in frog and turtle retinas. The NR2C and NR2D subunits were localized in glial Müller cells, while the NR1 subunit had both neuronal and glial localization. Our results show that glial NMDA receptors differ from neuronal ones in their subunit composition. The functional significance of the NMDA receptors and their NR2C and NR2D subunits, in particular for the neuron-glia interactions, is discussed. PMID:22386206

  5. DAPK1 Interaction with NMDA Receptor NR2B Subunits Mediates Brain Damage in Stroke

    PubMed Central

    Tu, Weihong; Xu, Xin; Peng, Lisheng; Zhong, Xiaofen; Zhang, Wenfeng; Soundarapandian, Mangala M.; Balel, Cherine; Wang, Manqi; Jia, Nali; Zhang, Wen; Lew, Frank; Chan, Sic Lung; Chen, Yanfang; Lu, Youming

    2010-01-01

    SUMMARY N-methyl-D-aspartate (NMDA) receptors constitute a major subtype of glutamate receptors at extra-synaptic sites that link multiple intracellular catabolic processes responsible for irreversible neuronal death. Here, we report that cerebral ischemia recruits death-associated protein kinase 1 (DAPK1) into the NMDA receptor NR2B protein complex in the cortex of adult mice. DAPK1 directly binds with the NMDA receptor NR2B C-terminal tail consisting of amino acid 1292–1304 (NR2BCT). A constitutively active DAPK1 phosphorylates NR2B subunit at Ser-1303 and in turn enhances the NR1/NR2B receptor channel conductance. Genetic deletion of DAPK1 or administration of NR2BCT that uncouples an activated DAPK1 from an NMDA receptor NR2B subunit in vivo in mice blocks injurious Ca2+ influx through NMDA receptor channels at extrasynaptic sites and protects neurons against cerebral ischemic insults. Thus, DAPK1 physically and functionally interacts with the NMDA receptor NR2B subunit at extra-synaptic sites and this interaction acts as a central mediator for stroke damage. PMID:20141836

  6. The NMDA receptor NR2A subunit regulates proliferation of MKN45 human gastric cancer cells

    SciTech Connect

    Watanabe, Kanako; Kanno, Takeshi; Oshima, Tadayuki; Miwa, Hiroto; Tashiro, Chikara; Nishizaki, Tomoyuki

    2008-03-07

    The present study investigated proliferation of MKN28 and MKN45 human gastric cancer cells regulated by the N-methyl-D-aspartate (NMDA) receptor subunit. The NMDA receptor antagonist DL-2-amino-5-phosphonovaleric acid (AP5) inhibited proliferation of MKN45 cells, but not MKN28 cells. Of the NMDA subunits such as NR1, NR2 (2A, 2B, 2C, and 2D), and NR3 (3A and 3B), all the NMDA subunit mRNAs except for the NR2B subunit mRNA were expressed in both MKN28 and MKN45 cells. MKN45 cells were characterized by higher expression of the NR2A subunit mRNA and lower expression of the NR1 subunit mRNA, but MKN28 otherwise by higher expression of the NR1 subunit mRNA and lower expression of the NR2A subunit mRNA. MKN45 cell proliferation was also inhibited by silencing the NR2A subunit-targeted gene. For MKN45 cells, AP5 or knocking-down the NR2A subunit increased the proportion of cells in the G{sub 1} phase of cell cycling and decreased the proportion in the S/G{sub 2} phase. The results of the present study, thus, suggest that blockage of NMDA receptors including the NR2A subunit suppresses MKN45 cell proliferation due to cell cycle arrest at the G{sub 1} phase; in other words, the NR2A subunit promotes MKN45 cell proliferation by accelerating cell cycling.

  7. Domain interaction between NMDA receptor subunits and the postsynaptic density protein PSD-95.

    PubMed

    Kornau, H C; Schenker, L T; Kennedy, M B; Seeburg, P H

    1995-09-22

    The N-methyl-D-aspartate (NMDA) receptor subserves synaptic glutamate-induced transmission and plasticity in central neurons. The yeast two-hybrid system was used to show that the cytoplasmic tails of NMDA receptor subunits interact with a prominent postsynaptic density protein PSD-95. The second PDZ domain in PSD-95 binds to the seven-amino acid, COOH-terminal domain containing the terminal tSXV motif (where S is serine, X is any amino acid, and V is valine) common to NR2 subunits and certain NR1 splice forms. Transcripts encoding PSD-95 are expressed in a pattern similar to that of NMDA receptors, and the NR2B subunit co-localizes with PSD-95 in cultured rat hippocampal neurons. The interaction of these proteins may affect the plasticity of excitatory synapses. PMID:7569905

  8. Rat intra-hippocampal NMDA infusion induces cell-specific damage and changes in expression of NMDA and GABAA receptor subunits.

    PubMed

    Rambousek, Lukas; Kleteckova, Lenka; Kubesova, Anna; Jirak, Daniel; Vales, Karel; Fritschy, Jean-Marc

    2016-06-01

    Excessive stimulation of NMDA receptors with glutamate or other potent agonists such as NMDA leads to excitotoxicity and neural injury. In this study, we aimed to provide insight into an animal model of brain excitotoxic damage; single unilateral infusion of NMDA at mild dose into the hippocampal formation. NMDA infusion induced chronic, focal neurodegeneration in the proximity of the injection site. The lesion was accompanied by severe and progressive neuroinflammation and affected preferentially principal neurons while sparing GABAergic interneurons. Furthermore, the unilateral lesion did not cause significant impairment of spatial learning abilities. Finally, GluN1 and GluN2B subunits of NMDA receptor were significantly upregulated up to 3 days after the NMDA infusion, while GABAA α5 subunit was downregulated at 30 days after the lesion. Taken together, a single infusion of NMDA into the hippocampal formation represents an animal model of excitotoxicity-induced chronic neurodegeneration of principal neurons accompanied by severe neuroinflammation and subunit specific changes in NMDA and GABAA receptors. PMID:26930443

  9. Structure of the Zinc-Bound Amino-Terminal Domain of the NMDA Receptor NR2B Subunit

    SciTech Connect

    Karakas, E.; Simorowski, N; Furukawa, H

    2009-01-01

    N-methyl-D-aspartate (NMDA) receptors belong to the family of ionotropic glutamate receptors (iGluRs) that mediate the majority of fast excitatory synaptic transmission in the mammalian brain. One of the hallmarks for the function of NMDA receptors is that their ion channel activity is allosterically regulated by binding of modulator compounds to the extracellular amino-terminal domain (ATD) distinct from the L-glutamate-binding domain. The molecular basis for the ATD-mediated allosteric regulation has been enigmatic because of a complete lack of structural information on NMDA receptor ATDs. Here, we report the crystal structures of ATD from the NR2B NMDA receptor subunit in the zinc-free and zinc-bound states. The structures reveal the overall clamshell-like architecture distinct from the non-NMDA receptor ATDs and molecular determinants for the zinc-binding site, ion-binding sites, and the architecture of the putative phenylethanolamine-binding site.

  10. NMDA Receptors Containing the GluN2D Subunit Control Neuronal Function in the Subthalamic Nucleus.

    PubMed

    Swanger, Sharon A; Vance, Katie M; Pare, Jean-François; Sotty, Florence; Fog, Karina; Smith, Yoland; Traynelis, Stephen F

    2015-12-01

    The GluN2D subunit of the NMDA receptor is prominently expressed in the basal ganglia and associated brainstem nuclei, including the subthalamic nucleus (STN), globus pallidus, striatum, and substantia nigra. However, little is known about how GluN2D-containing NMDA receptors contribute to synaptic activity in these regions. Using Western blotting of STN tissue punches, we demonstrated that GluN2D is expressed in the rat STN throughout development [age postnatal day 7 (P7)-P60] and in the adult (age P120). Immunoelectron microscopy of the adult rat brain showed that GluN2D is predominantly expressed in dendrites, unmyelinated axons, and axon terminals within the STN. Using subunit-selective allosteric modulators of NMDA receptors (TCN-201, ifenprodil, CIQ, and DQP-1105), we provide evidence that receptors containing the GluN2B and GluN2D subunits mediate responses to exogenously applied NMDA and glycine, as well as synaptic NMDA receptor activation in the STN of rat brain slices. EPSCs in the STN were mediated primarily by AMPA and NMDA receptors and GluN2D-containing NMDA receptors controlled the slow deactivation time course of EPSCs in the STN. In vivo recordings from the STN of anesthetized adult rats demonstrated that the spike firing rate was increased by the GluN2C/D potentiator CIQ and decreased by the GluN2C/D antagonist DQP-1105, suggesting that NMDA receptor activity can influence STN output. These data indicate that the GluN2B and GluN2D NMDA receptor subunits contribute to synaptic activity in the STN and may represent potential therapeutic targets for modulating subthalamic neuron activity in neurological disorders such as Parkinson's disease. PMID:26631477

  11. An alternating GluN1-2-1-2 subunit arrangement in mature NMDA receptors.

    PubMed

    Riou, Morgane; Stroebel, David; Edwardson, J Michael; Paoletti, Pierre

    2012-01-01

    NMDA receptors (NMDARs) form glutamate-gated ion channels that play a critical role in CNS physiology and pathology. Together with AMPA and kainate receptors, NMDARs are known to operate as tetrameric complexes with four membrane-embedded subunits associating to form a single central ion-conducting pore. While AMPA and some kainate receptors can function as homomers, NMDARs are obligatory heteromers composed of homologous but distinct subunits, most usually of the GluN1 and GluN2 types. A fundamental structural feature of NMDARs, that of the subunit arrangement around the ion pore, is still controversial. Thus, in a typical NMDAR associating two GluN1 and two GluN2 subunits, there is evidence for both alternating 1/2/1/2 and non-alternating 1/1/2/2 arrangements. Here, using a combination of electrophysiological and cross-linking experiments, we provide evidence that functional GluN1/GluN2A receptors adopt the 1/2/1/2 arrangement in which like subunits are diagonal to one another. Moreover, based on the recent crystal structure of an AMPA receptor, we show that in the agonist-binding and pore regions, the GluN1 subunits occupy a "proximal" position, closer to the central axis of the channel pore than that of GluN2 subunits. Finally, results obtained with reducing agents that differ in their membrane permeability indicate that immature (intracellular) and functional (plasma-membrane inserted) pools of NMDARs can adopt different subunit arrangements, thus stressing the importance of discriminating between the two receptor pools in assembly studies. Elucidating the quaternary arrangement of NMDARs helps to define the interface between the subunits and to understand the mechanism and pharmacology of these key signaling receptors. PMID:22493736

  12. Cisplatin induces neuronal activation and increases central AMPA and NMDA receptor subunit gene expression in mice.

    PubMed

    Holland, Ruby A; Leonard, John J; Kensey, Nicholas A; Hannikainen, Paavali A; De Jonghe, Bart C

    2014-09-01

    Although rats and mice do not vomit, these species are widely studied as models of energy balance and sickness behavior. Previous work has shown that rats exhibit similar neuroanatomical activation of brain and visceral afferent pathways following cisplatin chemotherapy compared to vomiting species. However, the neural response to cisplatin in mice is understudied. Here, food intake, body weight, and central c-Fos immunofluorescence were analyzed in the hindbrains of male C57BL/6 mice following IP saline or cisplatin (5mg/kg, and 20mg/kg doses). As glutamate receptor signaling is classically linked to inhibitory feeding pathways in the rodent, gene expression of selected α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and N-methyl-d-aspartic acid (NMDA) receptor subunits were assessed in the dorsal vagal complex (DVC), parabrachial nucleus (PBN), amygdala, and bed nucleus of the stria terminalis (BNST). Our results show dose-dependent reductions in food intake and body weight following cisplatin treatment, as well as increases in cisplatin-induced c-Fos in the PBN and throughout the DVC. Quantitative PCR analysis shows cisplatin-induced increases in NMDA receptor subunit expression, particularly NR2B, in the DVC, PBN, BNST, and amygdala. In addition, upregulation of AMPA receptor subunits (GluA1 and/or GluA2) were observed in all regions examined except the amygdala. Taken together, these results suggest similar neural pathways mediating cisplatin effects in mice compared to other well-studied species, which are likely mediated by central upregulation of AMPA and NMDA receptors. PMID:24582677

  13. NMDA Receptors Containing the GluN2D Subunit Control Neuronal Function in the Subthalamic Nucleus

    PubMed Central

    Swanger, Sharon A.; Vance, Katie M.; Pare, Jean-François; Sotty, Florence; Fog, Karina; Smith, Yoland

    2015-01-01

    The GluN2D subunit of the NMDA receptor is prominently expressed in the basal ganglia and associated brainstem nuclei, including the subthalamic nucleus (STN), globus pallidus, striatum, and substantia nigra. However, little is known about how GluN2D-containing NMDA receptors contribute to synaptic activity in these regions. Using Western blotting of STN tissue punches, we demonstrated that GluN2D is expressed in the rat STN throughout development [age postnatal day 7 (P7)–P60] and in the adult (age P120). Immunoelectron microscopy of the adult rat brain showed that GluN2D is predominantly expressed in dendrites, unmyelinated axons, and axon terminals within the STN. Using subunit-selective allosteric modulators of NMDA receptors (TCN-201, ifenprodil, CIQ, and DQP-1105), we provide evidence that receptors containing the GluN2B and GluN2D subunits mediate responses to exogenously applied NMDA and glycine, as well as synaptic NMDA receptor activation in the STN of rat brain slices. EPSCs in the STN were mediated primarily by AMPA and NMDA receptors and GluN2D-containing NMDA receptors controlled the slow deactivation time course of EPSCs in the STN. In vivo recordings from the STN of anesthetized adult rats demonstrated that the spike firing rate was increased by the GluN2C/D potentiator CIQ and decreased by the GluN2C/D antagonist DQP-1105, suggesting that NMDA receptor activity can influence STN output. These data indicate that the GluN2B and GluN2D NMDA receptor subunits contribute to synaptic activity in the STN and may represent potential therapeutic targets for modulating subthalamic neuron activity in neurological disorders such as Parkinson's disease. SIGNIFICANCE STATEMENT The subthalamic nucleus (STN) is a key component of the basal ganglia, a group of subcortical nuclei that control movement and are dysregulated in movement disorders such as Parkinson's disease. Subthalamic neurons receive direct excitatory input, but the pharmacology of excitatory

  14. GluN2B subunit-containing NMDA receptor antagonists prevent Abeta-mediated synaptic plasticity disruption in vivo.

    PubMed

    Hu, Neng-Wei; Klyubin, Igor; Anwyl, Roger; Anwy, Roger; Rowan, Michael J

    2009-12-01

    Currently, treatment with the relatively low-affinity NMDA receptor antagonist memantine provides limited benefit in Alzheimer's disease (AD). One probable dose-limiting factor in the use of memantine is the inhibition of NMDA receptor-dependent synaptic plasticity mechanisms believed to underlie certain forms of memory. Moreover, amyloid-beta protein (Abeta) oligomers that are implicated in causing the cognitive deficits of AD potently inhibit this form of plasticity. Here we examined if subtype-preferring NMDA receptor antagonists could preferentially protect against the inhibition of NMDA receptor-dependent plasticity of excitatory synaptic transmission by Abeta in the hippocampus in vivo. Using doses that did not affect control plasticity, antagonists selective for NMDA receptors containing GluN2B but not other GluN2 subunits prevented Abeta(1-42) -mediated inhibition of plasticity. Evidence that the proinflammatory cytokine TNFalpha mediates this deleterious action of Ass was provided by the ability of TNFalpha antagonists to prevent Abeta(1-42) inhibition of plasticity and the abrogation of a similar disruptive effect of TNFalpha using a GluN2B-selective antagonist. Moreover, at nearby synapses that were resistant to the inhibitory effect of TNFalpha, Abeta(1-42) did not significantly affect plasticity. These findings suggest that preferentially targeting GluN2B subunit-containing NMDARs may provide an effective means of preventing cognitive deficits in early Alzheimer's disease. PMID:19918059

  15. Role for the NR2B Subunit of the NMDA Receptor in Mediating Light Input to the Circadian System

    PubMed Central

    Wang, LM; Schroeder, A; Loh, D; Smith, D; Lin, K; Han, JH; Michel, S; Hummer, DL; Ehlen, JC; Albers, HE; Colwell, CS

    2008-01-01

    Light information reaches the suprachiasmatic nucleus (SCN) through a subpopulation of retinal ganglion cells that utilize glutamate as a neurotransmitter. A variety of evidence suggests that the release of glutamate then activates N-methyl-Daspartate (NMDA) receptors within the SCN and triggers a signaling cascade that ultimately leads to phase shifts in the circadian system. In this study, we first sought to explore the role of the NR2B subunit in mediating the effects of light on the circadian system. We found that localized microinjection of the NR2B subunit antagonist ifenprodil into the SCN region inhibits the magnitude of light-induced phase shifts of the circadian rhythm in wheel-running activity. Next, we found that the NR2B message and levels of phospho-NR2B levels vary with time of day in SCN tissue using semi-quantitative real-time PCR and Western blot analysis, respectively. Functionally, we found that blocking the NR2B subunit with ifenprodil significantly reduced the magnitude of NMDA currents recorded in SCN neurons. Ifenprodil also significantly reduced the magnitude of NMDA-induced calcium changes in SCN cells. Together, these results demonstrate that the NR2B subunit is an important component of NMDA receptor mediated responses within SCN neurons and that this subunit contributes to light-induced phase shifts of the mammalian circadian system. PMID:18380671

  16. Distribution of NMDA receptor subunit NR1 in Arctic ground squirrel central nervous system

    PubMed Central

    Zhao, Huiwen W.; Christian, Sherri L.; Castillo, Marina R.; Bult-Ito, Abel; Drew, Kelly L.

    2013-01-01

    Hibernation is a natural model of neuroprotection and adult synaptic plasticity. NMDA receptors (NMDAR), which play key roles in excitotoxicity and synaptic plasticity, have not been characterized in a hibernating species. Tolerance to excitotoxicity and cognitive enhancement in Arctic ground squirrels (AGS, Spermophilus parryii) suggests that NMDAR expression may decrease in hibernation and increase upon arousal. NMDAR consist of at least one NMDAR1 (NR1) subunit, which is required for receptor function. Localization of NR1 reflects localization of the majority, if not all, NMDAR complexes. The purpose of this study, therefore, was to characterize the distribution of NR1 subunits in AGS central nervous system using immunohistochemistry. In addition, we compare NR1 expression in hippocampus of hibernating AGS (hAGS) and inter-bout euthermic AGS (ibeAGS) and assess changes in cell somata size using NR1 stained sections in three hippocampal sub-regions (CA1, CA3, and dentate gyrus). For the first time, we report that immunoreactivity of anti-NR1 is widely distributed throughout the central nervous system in AGS and is similar to other species. No differences exist in the expression and distribution of NR1 in hAGS and ibeAGS. However, we report a significant decrease in size of hippocampal CA1 and dentate gyrus NR1-expressing neuronal somata during hibernation torpor. PMID:17097266

  17. Reduced levels of NR2A and NR2B subunits of NMDA receptor and PSD-95 in the prefrontal cortex in major depression

    PubMed Central

    Feyissa, Anteneh M.; Zyga, Agata; Stockmeier, Craig A.; Karolewicz, Beata

    2009-01-01

    Recent neuroimaging and postmortem studies have demonstrated abnormalities in glutamatergic transmission in major depression. Glutamate NMDA (N-methyl-D-aspartate) receptors are one of the major mediators of excitatory neurotransmission in the central nervous system. At synaptic sites, NMDA receptors are linked with postsynaptic density protein-95 (PSD-95) that plays a key role in mediating trafficking, clustering, and downstream signaling events, following receptor activation. In this study, we examined the expression of NMDA receptor subunits NR1, NR2A, and NR2B as well as PSD-95 in the anterior prefrontal cortex (PFC) using Western blot method. Cortical samples were obtained from age, gender and postmortem interval matched depressed and psychiatrically healthy controls. The results revealed that there was a reduced expression of the NMDA receptor subunits NR2A (−54%) and NR2B (−48%), and PSD-95 protein level (−40%) in the PFC of depressed subjects relative to controls, with no change in the NR1 subunit. The alterations in NMDA receptor subunits, especially the NR2A and NR2B, as well as PSD-95 suggest an abnormality in the NMDA receptor signaling in the PFC in major depression. Our findings in conjunction with recent clinical, cellular, and neuroimaging studies further implicate the involvement of glutamate neurotransmission in the pathophysiology of depression. This study provides additional evidence that NMDA receptor complex is a target for discovery of novel antidepressants. PMID:18992785

  18. Localization of a gene for a glutamate binding subunit of a NMDA receptor (GRINA) to 8q24

    SciTech Connect

    Lewis, T.B.; DuPont, B.R.; Leach, R.

    1996-02-15

    This article reports on the localization of a gene for a glutamate binding subunit of an N-methyl-D-aspartate (NMDA) receptor, called GRINA, to human chromosome 8q24 using fluorescence in situ hybridization and radiation hybridization mapping. This gene mapped outside the critical region for benign familial neonatal convulsions (BFNC), a rare form of epilepsy; however, GRINA could be the causative genetic factor inducing idiopathic generalized epilepsy. Further studies need to be conducted. 15 refs., 2 figs.

  19. [Beta]-Adrenergic Receptor Activation Rescues Theta Frequency Stimulation-Induced LTP Deficits in Mice Expressing C-Terminally Truncated NMDA Receptor GluN2A Subunits

    ERIC Educational Resources Information Center

    Moody, Teena D.; Watabe, Ayako M.; Indersmitten, Tim; Komiyama, Noboru H.; Grant, Seth G. N.; O'Dell, Thomas J.

    2011-01-01

    Through protein interactions mediated by their cytoplasmic C termini the GluN2A and GluN2B subunits of NMDA receptors (NMDARs) have a key role in the formation of NMDAR signaling complexes at excitatory synapses. Although these signaling complexes are thought to have a crucial role in NMDAR-dependent forms of synaptic plasticity such as long-term…

  20. Regulation of NMDA receptor subunit mRNA expression in the guinea pig vestibular nuclei following unilateral labyrinthectomy.

    PubMed

    Sans, N; Sans, A; Raymond, J

    1997-10-01

    The localization of neurons expressing mRNAs for the NR1 and NR2A-D subunits of the glutamatergic NMDA receptor was examined by non-radioactive in situ hybridization throughout the guinea pig vestibular nuclei. After deafferentation of the vestibular nuclei by unilateral labyrinthectomy, modifications of the mRNA distributions were followed for 30 days. A quantitative analysis was performed in the medial vestibular nucleus by comparison of the labelled neurons in the ipsi- and contra-lateral nuclei. In vestibular nuclei, the NR1 subunit mRNA was found in various populations of neurons. The NR2A and NR2C subunit mRNAs were less widely distributed, whereas little NR2D mRNA was detected and only rare cells contained NR2B mRNA. NR1 and NR2A-D mRNAs were colocalized in some but not other neuronal types. Twenty hours after the lesion, there was a transient ipsilateral increase of NR1 mRNA level in the medial vestibular nucleus, followed by a decrease 48 h after the lesion and, at 3 days, by recovery to the control level. An ipsilateral increase in the mRNA level of NR2C subunit was detected 20 h after lesion and maintained at 48 h. No significant changes were apparent in NR2A, NR2B and NR2D mRNA levels. The distributions and the differential signal intensities of NR2A-D mRNAs suggest various subunit organizations of the NMDA receptors in different neurons of the vestibular nuclei. Neuronal plasticity reorganizations in the vestibular nuclei following unilateral labyrinthectomy appear to include only changes in NR1 and NR2C mRNA levels modifying the functional diversity of the NMDA receptor in the ipsilateral medial vestibular nucleus neurons. The transient changes in NR1 and the NR2C subunit mRNA expressions in response to sensory deprivation are consistent with an active role for NMDA receptors in the appearance and development of the vestibular compensatory process. PMID:9421163

  1. Setdb1 histone methyltransferase regulates mood-related behaviors and expression of the NMDA receptor subunit NR2B.

    PubMed

    Jiang, Yan; Jakovcevski, Mira; Bharadwaj, Rahul; Connor, Caroline; Schroeder, Frederick A; Lin, Cong L; Straubhaar, Juerg; Martin, Gilles; Akbarian, Schahram

    2010-05-26

    Histone methyltransferases specific for the histone H3-lysine 9 residue, including Setdb1 (Set domain, bifurcated 1)/Eset/Kmt1e are associated with repressive chromatin remodeling and expressed in adult brain, but potential effects on neuronal function and behavior remain unexplored. Here, we report that transgenic mice with increased Setdb1 expression in adult forebrain neurons show antidepressant-like phenotypes in behavioral paradigms for anhedonia, despair, and learned helplessness. Chromatin immunoprecipitation in conjunction with DNA tiling arrays (ChIP-chip) revealed that genomic occupancies of neuronal Setdb1 are limited to <1% of annotated genes, which include the NMDA receptor subunit NR2B/Grin2B and other ionotropic glutamate receptor genes. Chromatin conformation capture and Setdb1-ChIP revealed a loop formation tethering the NR2B/Grin2b promoter to the Setdb1 target site positioned 30 kb downstream of the transcription start site. In hippocampus and ventral striatum, two key structures in the neuronal circuitry regulating mood-related behaviors, Setdb1-mediated repressive histone methylation at NR2B/Grin2b was associated with decreased NR2B expression and EPSP insensitivity to pharmacological blockade of NR2B, and accelerated NMDA receptor desensitization consistent with a shift in NR2A/B subunit ratios. In wild-type mice, systemic treatment with the NR2B antagonist, Ro25-6981 [R-(R,S)-alpha-(4-hydroxyphenyl)-beta-methyl-4-(phenylmethyl)-1-piperidine propranol], and hippocampal small interfering RNA-mediated NR2B/Grin2b knockdown resulted in behavioral changes similar to those elicited by the Setdb1 transgene. Together, these findings point to a role for neuronal Setdb1 in the regulation of affective and motivational behaviors through repressive chromatin remodeling at a select set of target genes, resulting in altered NMDA receptor subunit composition and other molecular adaptations. PMID:20505083

  2. NMDA receptor contributions to visual contrast coding

    PubMed Central

    Manookin, Michael B.; Weick, Michael; Stafford, Benjamin K.; Demb, Jonathan B.

    2010-01-01

    Summary In the retina, it is not well understood how visual processing depends on AMPA- and NMDA-type glutamate receptors. Here, we investigated how these receptors contribute to contrast coding in identified guinea pig ganglion cell types, in vitro. NMDA-mediated responses were negligible in ON α cells but substantial in OFF α and δ cells. OFF δ cell NMDA receptors were composed of GluN2B subunits. Using a novel deconvolution method, we determined the individual contributions of AMPA, NMDA and inhibitory currents to light responses of each cell type. OFF α and δ cells used NMDA receptors for encoding either the full contrast range (α), including near-threshold responses, or only a high range (δ). However, contrast sensitivity depended substantially on NMDA receptors only in OFF α cells. NMDA receptors contribute to visual contrast coding in a cell-type specific manner. Certain cell types generate excitatory responses using primarily AMPA receptors or disinhibition. PMID:20670835

  3. NMDA receptor subunits and associated signaling molecules mediating antidepressant-related effects of NMDA-GluN2B antagonism

    PubMed Central

    Kiselycznyk, Carly; Jury, Nicholas; Halladay, Lindsay; Nakazawa, Kazu; Mishina, Masayoshi; Sprengel, Rolf; Grant, Seth G.N.; Svenningsson, Per; Holmes, Andrew

    2015-01-01

    Drugs targeting the glutamate N-methyl-D-aspartate receptor (NMDAR) may be efficacious for treating mood disorders, as exemplified by the rapid antidepressant effects produced by single administration of the NMDAR antagonist ketamine. Though the precise mechanisms underlying the antidepressant-related effects of NMDAR antagonism remain unclear, recent studies implicate specific NMDAR subunits, including GluN2A and GluN2B, as well as the alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor (AMPAR) subunit glutamate receptor interacting molecule, PSD-95. Here, integrating mutant and pharmacological in mice, we investigated the contribution of these subunits and molecules to antidepressant-related behaviors and the antidepressant-related effects of the GluN2B blocker, Ro 25-6981. We found that global deletion of GluA1 or PSD-95 reduced forced swim test (FST) immobility, mimicking the antidepressant-related effect produced by systemically administered Ro 25-6981 in C57BL/6J mice. Moreover, the FST antidepressant-like effects of systemic Ro 25-6981 were intact in mutants with global GluA1 deletion or GluN1 deletion in forebrain interneurons, but were absent in mutants constitutively lacking GluN2A or PSD-95. Next, we found that microinfusing Ro 25-6981 into the medial prefrontal cortex (mPFC), but not basolateral amygdala, of C57BL/6J mice was sufficient to produce an antidepressant-like effect. Together, these findings extend and refine current understanding of the mechanisms mediating antidepressant-like effects produced by NMDAR-GluN2B antagonists, and may inform the development of a novel class of medications for treating depression that target the GluN2B subtype of NMDAR. PMID:25800971

  4. Brain-derived neurotrophic factor acutely enhances tyrosine phosphorylation of the AMPA receptor subunit GluR1 via NMDA receptor-dependent mechanisms.

    PubMed

    Wu, Kuo; Len, Guo-Wei; McAuliffe, Geoff; Ma, Chia; Tai, Jessica P; Xu, Fei; Black, Ira B

    2004-11-01

    Brain-derived growth factor (BDNF) acutely regulates synaptic transmission and modulates hippocampal long-term potentiation (LTP) and long-term depression (LTD), cellular models of plasticity associated with learning and memory. Our previous studies revealed that BDNF rapidly increases phosphorylation of NMDA receptor subunits NR1 and NR2B in the postsynaptic density (PSD), potentially linking receptor phosphorylation to synaptic plasticity. To further define molecular mechanisms governing BDNF actions, we examined tyrosine phosphorylation of GluR1, the most well-characterized subunit of AMPA receptors. Initially, we investigated synaptoneurosomes that contain intact pre- and postsynaptic elements. Incubation of synaptoneurosomes with BDNF for 5 min increased tyrosine phosphorylation of GluR1 in a dose-dependent manner, with a maximal, 4-fold enhancement at 10 ng/ml BDNF. NGF had no effects, suggesting the specificity of BDNF actions. Subsequently, we found that BDNF elicited a maximal, 2.5-fold increase in GluR1 phosphorylation in the PSD at 250 ng/ml BDNF within 5 min, suggesting that BDNF enhances the phosphorylation through postsynaptic mechanisms. Activation of trkB receptors was critical as k252-a, an inhibitor of trk receptor tyrosine kinase, blocked the BDNF-activated GluR1 phosphorylation. In addition, AP-5 and MK 801, NMDA receptor antagonists, blocked BDNF enhancement of phosphorylation in synaptoneurosomes or PSDs. Conversely, NMDA, the specific receptor agonist, evoked respective 3.8- and 2-fold increases in phosphorylation in synaptoneurosomes and PSDs within 5 min, mimicking the effects of BDNF. These findings raise the possibility that BDNF modulates GluR1 activity via changes in NMDA receptor function. Moreover, incubation of synaptoneurosomes or PSDs with BDNF and ifenprodil, a specific NR2B antagonist, reproduced the results of AP-5 and MK-801. Finally, coexposure of synaptoneurosomes or PSDs to BDNF and NMDA was not additive, suggesting that

  5. Nanoparticle-rich diesel exhaust affects hippocampal-dependent spatial learning and NMDA receptor subunit expression in female mice.

    PubMed

    Win-Shwe, Tin-Tin; Yamamoto, Shoji; Fujitani, Yuji; Hirano, Seishiro; Fujimaki, Hidekazu

    2012-08-01

    We investigated the effect of exposure to nanoparticle-rich diesel exhaust (NRDE) on hippocampal-dependent spatial learning and memory function-related gene expressions in female mice. Female BALB/c mice were exposed to clean air, middle-dose NRDE (M-NRDE), high-dose NRDE (H-NRDE) or filtered diesel exhaust (F-DE) for three months. A Morris water maze apparatus was used to examine spatial learning. The expression levels of the N-methyl-D-aspartate (NMDA) receptor subunit, proinflammatory cytokines and neurotrophin mRNAs in the hippocampus were then investigated using real-time RT-PCR. Mice exposed to H-NRDE required a longer time to reach the hidden platform and showed higher mRNA expression levels of the NMDA receptor subunit NR2A, the proinflammatory cytokine CCL3, and brain-derived neurotrophic factor (BDNF) in the hippocampus, compared with the findings in the control group. These results indicate that three months of exposure to NRDE affected spatial learning and memory function-related gene expressions in the female mouse hippocampus. PMID:21663545

  6. Unique domain anchoring of Src to synaptic NMDA receptors via the mitochondrial protein NADH dehydrogenase subunit 2.

    PubMed

    Gingrich, Jeffrey R; Pelkey, Kenneth A; Fam, Sami R; Huang, Yueqiao; Petralia, Ronald S; Wenthold, Robert J; Salter, Michael W

    2004-04-20

    Src is the prototypic protein tyrosine kinase and is critical for controlling diverse cellular functions. Regions in Src define structural and functional domains conserved in many cell signaling proteins. Src also contains a region of low sequence conservation termed the unique domain, the function of which has until now remained enigmatic. Here, we show that the unique domain of Src is a protein-protein interaction region and we identify NADH dehydrogenase subunit 2 (ND2) as a Src unique domain-interacting protein. ND2 is a subunit of complex I in mitochondria, but we find that ND2 interacts with Src outside this organelle at excitatory synapses in the brain. ND2 acts as an adapter protein anchoring Src to the N-methyl-d-aspartate (NMDA) receptor complex, and is crucial for Src regulation of synaptic NMDA receptor activity. By showing an extramitochondrial action for a protein encoded in the mitochondrial genome, we identify a previously unsuspected means by which mitochondria regulate cellular function, suggesting a new paradigm that may be of general relevance for control of Src signaling. PMID:15069201

  7. Impaired Discrimination Learning in Mice Lacking the NMDA Receptor NR2A Subunit

    ERIC Educational Resources Information Center

    Brigman, Jonathan L.; Feyder, Michael; Saksida, Lisa M.; Bussey, Timothy J.; Mishina, Masayoshi; Holmes, Andrew

    2008-01-01

    N-Methyl-D-aspartate receptors (NMDARs) mediate certain forms of synaptic plasticity and learning. We used a touchscreen system to assess NR2A subunit knockout mice (KO) for (1) pairwise visual discrimination and reversal learning and (2) acquisition and extinction of an instrumental response requiring no pairwise discrimination. NR2A KO mice…

  8. Identification of a new site in the S1 ligand binding region of the NMDA receptor NR2A subunit involved in receptor activation by glutamate.

    PubMed

    Lummis, Sarah C R; Fletcher, Elizabeth J; Green, Tim

    2002-03-01

    Activation of N-methyl-d-aspartate (NMDA) receptors requires the binding of both glutamate and glycine to independent sites on the receptor. These ligands bind to NR2 and NR1 subunits respectively. Ligand binding residues are located in two non-contiguous domains, S1 and S2, which have been implicated in glutamate binding in other ionotropic glutamate receptor subunits. To further define the amino acids through which glutamate activates the receptor, we generated single-site mutations to the NR2A subunit, and expressed them with wild type NR1 in HEK 293 cells. Using calcium imaging and whole cell patch clamp we determined glutamate and glycine potencies. Of the eight residues mutated we identified five (E413, K484, A508, G685 and G688), whose mutation leads to a large reduction (from 4- to 1000-fold) in glutamate potency, consistent with a role for these residues in receptor activation by glutamate. The potency of glycine was largely unchanged by these mutations. Thus our results extend the knowledge base of residues involved in NMDA receptor function and identifies a new site in S1, in the region of A508, that has a role in receptor activation by glutamate. PMID:11955515

  9. Functional contributions of synaptically localized NR2B subunits of the NMDA receptor to synaptic transmission and long-term potentiation in the adult mouse CNS

    PubMed Central

    Miwa, Hideki; Fukaya, Masahiro; Watabe, Ayako M; Watanabe, Masahiko; Manabe, Toshiya

    2008-01-01

    The NMDA-type glutamate receptor is a heteromeric complex composed of the NR1 and at least one of the NR2 subunits. Switching from the NR2B to the NR2A subunit is thought to underlie functional alteration of the NMDA receptor during synaptic maturation, and it is generally believed that it results in preferential localization of NR2A subunits on the synaptic site and that of NR2B subunits on the extracellular site in the mature brain. It has also been proposed that activation of the NR2A and NR2B subunits results in long-term potentiation (LTP) and long-term depression (LTD), respectively. Furthermore, recent reports suggest that synaptic and extrasynaptic receptors may have distinct roles in synaptic plasticity as well as in gene expression associated with neuronal death. Here, we have investigated whether NR2B subunit-containing receptors are present and functional at mature synapses in the lateral nucleus of the amygdala (LA) and the CA1 region of the hippocampus, comparing their properties between the two brain regions. We have found, in contrast to the above hypotheses, that the NR2B subunit significantly contributes to synaptic transmission as well as LTP induction. Furthermore, its contribution is greater in the LA than in the CA1 region, and biophysical properties of NMDA receptors and the NR2B/NR2A ratio are different between the two brain regions. These results indicate that NR2B subunit-containing NMDA receptors accumulate on the synaptic site and are responsible for the unique properties of synaptic function and plasticity in the amygdala. PMID:18372311

  10. GluN3A: An NMDA Receptor Subunit with Exquisite Properties and Functions

    PubMed Central

    Kehoe, Laura A.

    2013-01-01

    N-methyl-D-aspartate receptors (NMDAR) are pivotal for synaptic plasticity and memory formation. Conventional NMDAR consist of heterotetrameric structures composed of GluN1 and GluN2 subunits. A third subunit, GluN3, can also assemble with NMDAR subunits giving a remarkable modification of their heteromeric structure, forming a “nonconventional” NMDAR. As a consequence, the stoichiometry and kinetic properties of the receptors are dramatically changed. Among the GluN3 family, the GluN3A subunit has been the focus of a large amount of studies during recent years. These studies reveal that GluN3A is transiently expressed during development and could play a role in the fine tuning of neuronal networks as well as associated diseases. Moreover, GluN3A distribution outside the postsynaptic densities, including perisynaptic astrocytes, places it at a strategic position to play an important role in the interactions between neurons and glial cells. This review highlights GluN3A properties and addresses its role in neurophysiology and associated pathologies. PMID:24386575

  11. N-Methyl-d-aspartate (NMDA) Receptor NR2 Subunit Selectivity of a Series of Novel Piperazine-2,3-dicarboxylate Derivatives: Preferential Blockade of Extrasynaptic NMDA Receptors in the Rat Hippocampal CA3-CA1 Synapse

    PubMed Central

    Feng, Bihua; Tsintsadze, Timur S.; Morley, Richard M.; Irvine, Mark W.; Tsintsadze, Vera; Lozovaya, Natasha A.; Jane, David E.; Monaghan, Daniel T.

    2009-01-01

    N-Methyl-d-aspartate (NMDA) receptor antagonists that are highly selective for specific NMDA receptor 2 (NR2) subunits have several potential therapeutic applications; however, to date, only NR2B-selective antagonists have been described. Whereas most glutamate binding site antagonists display a common pattern of NR2 selectivity, NR2A > NR2B > NR2C > NR2D (high to low affinity), (2S*,3R*)-1-(phenanthrene-2-carbonyl)piperazine-2,3-dicarboxylic acid (PPDA) has a low selectivity for NR2C- and NR2D-containing NMDA receptors. A series of PPDA derivatives were synthesized and then tested at recombinant NMDA receptors expressed in Xenopus laevis oocytes. In addition, the optical isomers of PPDA were resolved; the (−) isomer displayed a 50- to 80-fold greater potency than the (+) isomer. Replacement of the phenanthrene moiety of PPDA with naphthalene or anthracene did not improve selectivity. However, phenylazobenzoyl (UBP125) or phenylethynylbenzoyl (UBP128) substitution significantly improved selectivity for NR2B-, NR2C-, and NR2D-containing receptors over NR2A-containing NMDA receptors. Phenanthrene attachment at the 3 position [(2R*,3S*)-1-(phenanthrene-3-carbonyl)piperazine-2,3-dicarboxylic acid (UBP141); (2R*,3S*)-1-(9-bromophenanthrene-3-carbonyl)piperazine-2,3-dicarboxylic acid (UBP145); (2R*,3S*)-1-(9-chlorophenanthrene-3-carbonyl)piperazine-2,3-dicarboxylic acid (UBP160); and (2R*,3S*)-1-(9-iodophenanthrene-3-carbonyl)piperazine-2,3-dicarboxylic acid (UBP161)] displayed improved NR2D selectivity. UBP141 and its 9-brominated homolog (UBP145) both display a 7- to 10- fold selectivity for NR2D-containing receptors over NR2B- or NR2A-containing receptors. Schild analysis indicates that these two compounds are competitive glutamate binding site antagonists. Consistent with a physiological role for NR2D-containing receptors in the hippocampus, UBP141 (5 μM) displayed greater selectivity than PPDA for inhibiting the slow-decaying component of the NMDA receptor

  12. Developmental origin dictates interneuron AMPA and NMDA receptor subunit composition and plasticity

    PubMed Central

    Matta, Jose A; Pelkey, Kenneth A; Craig, Michael T; Chittajallu, Ramesh; Jeffries, Brian W; McBain, Chris J

    2014-01-01

    Disrupted excitatory synapse maturation in GABAergic interneurons may promote neuropsychiatric disorders such as schizophrenia. However, establishing developmental programs for nascent synapses in GABAergic cells is confounded by their sparsity, heterogeneity and late acquisition of subtype-defining characteristics. We investigated synaptic development in mouse interneurons targeting cells by lineage from medial ganglionic eminence (MGE) or caudal ganglionic eminence (CGE) progenitors. MGE-derived interneuron synapses were dominated by GluA2-lacking AMPA-type glutamate receptors (AMPARs), with little contribution from NMDA-type receptors (NMDARs) throughout development. In contrast, CGE-derived cell synapses had large NMDAR components and used GluA2-containing AMPARs. In neonates, both MGE- and CGE-derived interneurons expressed primarily GluN2B subunit–containing NMDARs, which most CGE-derived interneurons retained into adulthood. However, MGE-derived interneuron NMDARs underwent a GluN2B-to-GluN2A switch that could be triggered acutely with repetitive synaptic activity. Our findings establish ganglionic eminence–dependent rules for early synaptic integration programs of distinct interneuron cohorts, including parvalbumin- and cholecystokinin-expressing basket cells. PMID:23852113

  13. Extracellular glutamate level and NMDA receptor subunit expression in mouse olfactory bulb following nanoparticle-rich diesel exhaust exposure.

    PubMed

    Win-Shwe, Tin-Tin; Mitsushima, Dai; Yamamoto, Shoji; Fujitani, Yuji; Funabashi, Toshiya; Hirano, Seishiro; Fujimaki, Hidekazu

    2009-08-01

    In this present study, we aimed to investigate the extracellular glutamate level and memory function-related gene expression in the mouse olfactory bulb after exposure of the animals to nanoparticle-rich diesel exhaust (NRDE) with or without bacterial cell wall component. Lipoteichoic acid (LTA), a cell wall component derived from Staphylococcus aureus, was used to induce systemic inflammation. Male BALB/c mice were exposed to clean air (particle concentration, 4.58 microg/m(3)) or NRDE (148.86 microg/m(3)) 5 h per day on 5 consecutive days of the week for 4 wk with or without weekly intraperitoneal injection of LTA. We examined the extracellular glutamate levels in the olfactory bulb using in vivo microdialysis and high-performance liquid chromatography assay. Then, we collected the olfactory bulb to examine the expression of N-methyl-D-aspartate (NMDA) receptor subunits (NR1, NR2A, and NR2B) and calcium/calmodulin-dependent protein kinase (CaMK) IV and cyclic AMP response element binding protein (CREB)-1 using real-time reverse-transcription polymerase chain reaction (RT-PCR). NRDE and/or LTA caused significantly increased extracellular glutamate levels in the olfactory bulb of mice. Moreover, the exposure of mice to NRDE upregulates NR1, NR2A, NR2B, and CaMKIV mRNAs in the olfactory bulb, while LTA upregulates only NR2B and CREB1 mRNAs. These findings suggest that NRDE and LTA cause glutamate-induced neurotoxicity separately and accompanied by changes in the expression of NMDA receptor subunits and related kinase and transcription factor in the mouse olfactory bulb. This is the first study to show the correlation between glutamate toxicity and memory function-related gene expressions in the mouse olfactory bulb following exposure to NRDE. PMID:19653804

  14. Bisphenol-A rapidly promotes dynamic changes in hippocampal dendritic morphology through estrogen receptor-mediated pathway by concomitant phosphorylation of NMDA receptor subunit NR2B

    SciTech Connect

    Xu Xiaohong Ye Yinping; Li Tao; Chen Lei; Tian Dong; Luo Qingqing; Lu Mei

    2010-12-01

    Bisphenol-A (BPA) is known to be a potent endocrine disrupter. Evidence is emerging that estrogen exerts a rapid influence on hippocampal synaptic plasticity and the dendritic spine density, which requires activation of NMDA receptors. In the present study, we investigated the effects of BPA (ranging from 1 to 1000 nM), focusing on the rapid dynamic changes in dendritic filopodia and the expressions of estrogen receptor (ER) {beta} and NMDA receptor, as well as the phosphorylation of NMDA receptor subunit NR2B in the cultured hippocampal neurons. A specific ER antagonist ICI 182,780 was used to examine the potential involvement of ERs. The results demonstrated that exposure to BPA (ranging from 10 to 1000 nM) for 30 min rapidly enhanced the motility and the density of dendritic filopodia in the cultured hippocampal neurons, as well as the phosphorylation of NR2B (pNR2B), though the expressions of NMDA receptor subunits NR1, NR2B, and ER{beta} were not changed. The antagonist of ERs completely inhibited the BPA-induced increases in the filopodial motility and the number of filopodia extending from dendrites. The increased pNR2B induced by BPA (100 nM) was also completely eliminated. Furthermore, BPA attenuated the effects of 17{beta}-estradiol (17{beta}-E{sub 2}) on the dendritic filopodia outgrowth and the expression of pNR2B when BPA was co-treated with 17{beta}-E{sub 2}. The present results suggest that BPA, like 17{beta}-E{sub 2}, rapidly results in the enhanced motility and density of dendritic filopodia in the cultured hippocampal neurons with the concomitant activation of NMDA receptor subunit NR2B via an ER-mediated signaling pathway. Meanwhile, BPA suppressed the enhancement effects of 17{beta}-E{sub 2} when it coexists with 17{beta}-E{sub 2}. These results provided important evidence suggesting the neurotoxicity of the low levels of BPA during the early postnatal development of the brain.

  15. SNARE Protein Syntaxin-1 Colocalizes Closely with NMDA Receptor Subunit NR2B in Postsynaptic Spines in the Hippocampus

    PubMed Central

    Hussain, Suleman; Ringsevjen, Håvard; Egbenya, Daniel L.; Skjervold, Torstein L.; Davanger, Svend

    2016-01-01

    Syntaxins are a family of membrane-integrated proteins that are instrumental in exocytosis of vesicles. Syntaxin-1 is an essential component of the presynaptic exocytotic fusion machinery in the brain and interacts with several other proteins. Syntaxin-1 forms a four-helical bundle complex with proteins SNAP-25 and VAMP2 that drives fusion of vesicles with the plasma membrane in the active zone (AZ). Little is known, however, about the ultrastructural localization of syntaxin-1 at the synapse. We have analyzed the intrasynaptic expression of syntaxin-1 in glutamatergic hippocampal synapses in detail by using quantitative postembedding immunogold labeling. Syntaxin-1 was present in highest concentrations at the presynaptic AZ, supporting its role in transmitter release. Presynaptic plasma membrane lateral to the AZ, as well as presynaptic cytoplasmic (PreCy) vesicles were also labeled. However, syntaxin-1 was also significantly expressed in postsynaptic spines, where it was localized at the postsynaptic density (PSD), at postsynaptic lateral membranes and in postsynaptic cytoplasm. Postsynaptically, syntaxin-1 colocalized in the nanometer range with the N-methyl-D-aspartate (NMDA) receptor subunit NR2B, but only weakly with the AMPA receptor subunits GluA2/3. This observation points to the possibility that syntaxin-1 may be involved with NR2B vesicular trafficking from cytoplasmic stores to the postsynaptic plasma membrane, thus facilitating synaptic plasticity. Confocal immunofluorescence double labeling with PSD-95 and ultrastructural fractionation of synaptosomes also confirm localization of syntaxin-1 at the PSD. PMID:26903802

  16. New advances in NMDA receptor pharmacology

    PubMed Central

    Ogden, Kevin K.; Traynelis, Stephen F.

    2011-01-01

    N-Methyl-D-aspartate (NMDA) receptors are tetrameric ion channels containing two of four possible GluN2 subunits. These receptors have been implicated for decades in neurological diseases such as stroke, traumatic brain injury, dementia, and schizophrenia. The GluN2 subunits contribute substantially to functional diversity of NMDA receptors and are distinctly expressed in development and among brain regions. Thus, subunit-selective antagonists and modulators that differentially target the GluN2 subunit might provide an opportunity to pharmacologically modify the function of select groups of neurons for therapeutic gain. A flurry of clinical, functional, and chemical studies have together reinvigorated efforts to identify subunit-selective modulators of NMDA receptor function, resulting in a handful of new compounds that appear to act at novel sites. Here we review the properties of new emerging classes of subunit-selective NMDA receptor modulators, which we predict will mark the beginning of a productive period of progress for NMDA receptor pharmacology. PMID:21996280

  17. A neuroligin-1-derived peptide stimulates phosphorylation of the NMDA receptor NR1 subunit and rescues MK-801-induced decrease in long-term potentiation and memory impairment.

    PubMed

    Korshunova, Irina; Gjørlund, Michelle D; Owczarek, Sylwia; Petersen, Anders V; Perrier, Jean-François; Gøtzsche, Casper René; Berezin, Vladimir

    2015-03-01

    Neuroligins (NLs) are postsynaptic adhesion molecules, interacting with presynaptic neurexins (NXs), which determine the differential formation of excitatory (glutamatergic, NL1) and inhibitory (GABAergic, NL2) synapses. We have previously demonstrated that treatment with a NL2-derived peptide, neurolide-2, reduces sociability and increase animal aggression. We hypothesized that interfering with NL1 function at the excitatory synapses might regulate synaptic plasticity and learning, and counteract memory deficits induced by N-methyl-d-aspartate (NMDA) receptor inhibition. First, neuronal NMDA receptor phosphorylation after treatment with NL1 or a mimetic peptide, neurolide-1, was quantified by immunoblotting. Subsequently, we investigated effects of neurolide-1 on long-term potentiation (LTP) induction in hippocampal slices compromised by NMDA receptor inhibitor MK-801. Finally, we investigated neurolide-1 effects on short- and long-term social and spatial memory in social recognition, Morris water-maze, and Y-maze tests. We found that subcutaneous neurolide-1 administration, restored hippocampal LTP compromised by NMDA receptor inhibitor MK-801. It counteracted MK-801-induced memory deficit in the water-maze and Y-maze tests after long-term treatment (24 h and 1-2 h before the test), but not after short-term exposure (1-2 h). Long-term exposure to neurolide-1 also facilitated social recognition memory. In addition, neurolide-1-induced phosphorylation of the NMDA receptor NR1 subunit on a site important for synaptic trafficking, potentially favoring synaptic receptor retention. Our findings emphasize the role of NL1-NMDA receptor interaction in cognition, and identify neurolide-1, as a valuable pharmacological tool to examine the in vivo role of postsynaptic NL1 in cognitive behavior in physiological and pathological conditions. PMID:26038702

  18. Differential expression of postsynaptic NMDA and AMPA receptor subunits in the hippocampus and prefrontal cortex of the flinders sensitive line rat model of depression.

    PubMed

    Treccani, Giulia; Gaarn du Jardin, Kristian; Wegener, Gregers; Müller, Heidi Kaastrup

    2016-11-01

    Glutamatergic abnormalities have recently been implicated in the pathophysiology of depression, and the ionotropic glutamate receptors in particular have been suggested as possible underlying molecular determinants. The Flinders Sensitive Line (FSL) rats constitute a validated model of depression with dysfunctional regulation of glutamate transmission relatively to their control strain Flinders Resistant Line (FRL). To gain insight into how signaling through glutamate receptors may be altered in the FSL rats, we investigated the expression and phosphorylation of AMPA and NMDA receptor subunits in an enriched postsynaptic fraction of the hippocampus and prefrontal cortex. Compared to the hippocampal postsynaptic fractions of FRL rats, FSL rats exhibited decreased and increased levels of the NMDA receptor subunits GluN2A and GluN2B, respectively, causing a lower ratio of GluN2A/GluN2B. The GluA2/GluA3 AMPA receptor subunit ratio was significantly decreased while the expression of the individual GluA1, GluA2, and GluA3 subunits were unaltered including phosphorylation levels of GluA1 at S831 and S845. There were no changes in the prefrontal cortex. These results support altered expression of postsynaptic glutamate receptors in the hippocampus of FSL rats, which may contribute to the depressive-like phenotype of these rats. PMID:27262028

  19. Changes in expression of splice cassettes of NMDA receptor GluN1 subunits within the frontal lobe and memory in mice during aging.

    PubMed

    Das, Siba R; Magnusson, Kathy R

    2011-09-12

    Age-related decline in memory has been associated with changes in mRNA and protein expression of different NMDA receptor subunits. The NMDA receptor GluN1 subunit appears to be necessary and sufficient for receptor function. There is evidence that the mRNA expressions of some splice forms of the subunit are influenced by aging and/or behavioral testing experience in old mice. The present study explored the relationships between behavioral testing experience and protein expression of different GluN1 subunit isoforms in the prefrontal/frontal cortex of the brain during aging. Aged C57BL/6 mice with behavioral testing experience showed declines in performance in both spatial working and reference memory tasks. Protein expression of GluN1 C-terminal cassettes C2 and C2', but not the C1 or N1 cassettes, was observed to decline with increasing age, regardless of experience. In middle-age animals, higher expressions of the GluN1 subunit and C2' cassette proteins were associated with good reference memory on initial search. Aged animals with a higher protein expression of GluN1 subunits containing C1 cassettes and the whole population of GluN1 subunits exhibited a closer proximity to the former platform location within the final phase of probe trials. However, the old mice with high expression of the C1 cassette did not show an accurate search during this phase. The old mice with lower expression of the C1 cassette protein more closely mimicked the performances of the young and middle-aged mice. These results indicate that there was heterogeneity in the effect of aging on the expression of the GluN1 subunits containing different splice cassettes. It also suggests that the GluN1 subunit might be most important for good reference memory during middle age, but this relationship may not be maintained into old age. PMID:21443909

  20. Okadaic acid induces epileptic seizures and hyperphosphorylation of the NR2B subunit of the NMDA receptor in rat hippocampus in vivo.

    PubMed

    Arias, Clorinda; Montiel, Teresa; Peña, Fernando; Ferrera, Patricia; Tapia, Ricardo

    2002-09-01

    Overactivation of N-methyl-D-aspartate (NMDA) glutamate receptors is closely related to epilepsy and excitotoxicity, and the phosphorylation of these receptors may facilitate glutamate-mediated synaptic transmission. Here we show that in awake rats the microinjection into the hippocampus of okadaic acid, a potent inhibitor of protein phosphatases 1 and 2A, induces in about 20 min intense electroencephalographic and behavioral limbic-type seizures, which are suppressed by the systemic administration of the NMDA receptor antagonist (+)-5-methyl-10,11-dihydro-5H-dibenzo-[a,d]cyclohepten-5,10-imine hydrogen maleate and by the intrahippocampal administration of 1-(5-isoquinolinesulfonyl)-2-methylpiperazine, an inhibitor of protein kinases. Two hours after okadaic acid, when the EEG seizures were intense, an increased serine phosphorylation of some hippocampal proteins, including an enhancement of the serine phosphorylation of the NMDA receptor subunit NR2B, was detected by immunoblotting. Twenty-four hours after okadaic acid a marked destruction of hippocampal CA1 region was observed, which was not prevented by the receptor antagonists. These findings suggest that hyperphosphorylation of glutamate receptors in vivo may result in an increased sensitivity to the endogenous transmitter and therefore induce neuronal hyperexcitability and epilepsy. PMID:12429230

  1. Postsynaptic density levels of the NMDA receptor NR1 subunit and PSD-95 protein in prefrontal cortex from people with schizophrenia

    PubMed Central

    Catts, Vibeke Sørensen; Derminio, Dominique Suzanne; Hahn, Chang-Gyu; Weickert, Cynthia Shannon

    2015-01-01

    Background: There is converging evidence of involvement of N-methyl-d-aspartate (NMDA) receptor hypofunction in the pathophysiology of schizophrenia. Our group recently identified a decrease in total NR1 mRNA and protein expression in the dorsolateral prefrontal cortex in a case-control study of individuals with schizophrenia (n=37/group). The NR1 subunit is critical to NMDA receptor function at the postsynaptic density, a cellular structure rich in the scaffolding protein, PSD-95. The extent to which the NMDA receptor NR1 subunit is altered at the site of action, in the postsynaptic density, is not clear. Aims: To extend our previous results by measuring levels of NR1 and PSD-95 protein in postsynaptic density-enriched fractions of prefrontal cortex from the same individuals in the case-control study noted above. Methods: Postsynaptic density-enriched fractions were isolated from fresh-frozen prefrontal cortex (BA10) and subjected to western blot analysis for NR1 and PSD-95. Results: We found a 20% decrease in NR1 protein (t(66)=−2.874, P=0.006) and a 30% decrease in PSD-95 protein (t(63)=−2.668, P=0.010) in postsynaptic density-enriched fractions from individuals with schizophrenia relative to unaffected controls. Conclusions: Individuals with schizophrenia have less NR1 protein, and therefore potentially fewer functional NMDA receptors, at the postsynaptic density. The associated decrease in PSD-95 protein at the postsynaptic density suggests that not only are glutamate receptors compromised in individuals with schizophrenia, but the overall spine architecture and downstream signaling supported by PSD-95 may also be deficient. PMID:27336043

  2. Association of the Small GTPase Rheb with the NMDA Receptor Subunit NR3A

    PubMed Central

    Sucher, Nikolaus J.; Yu, Eric; Chan, Shing Fai; Miri, Mitra; Lee, Benjamin J.; Xiao, Bo; Worley, Paul F.; Jensen, Frances E.

    2011-01-01

    The NMDAR subunit NR3A is most highly expressed during the second postnatal week, when synaptogenesis reaches peak levels. Genetic ablation or overexpression of the NR3A subunit negatively interferes with the maturation of cortical synapses and leads to changes in the shape and number of dendritic spines, the density of which is increased in NR3A knock-out mice and decreased in NR3A-overexpressing transgenic mice. Alterations in spine density have been linked to dysregulation of mTOR signaling and synaptic protein translation. Using a yeast two-hybrid system, we identified the mTOR-activating GTPase Rheb as an interacting protein of the NMDAR subunit NR3A. We confirmed the interaction in mammalian cells by expressing recombinant Rheb and NR3A and showed that Rheb and NR3A could be co-immunoprecipitated from synaptic plasma membranes from the developing rat brain. These data suggest that NR3A sequesters synaptic Rheb and might thus function as a break of the mTOR-dependent synaptic translation of protein. PMID:21135540

  3. Novel approach to probe subunit-specific contributions to N-methyl-D-aspartate (NMDA) receptor trafficking reveals a dominant role for NR2B in receptor recycling.

    PubMed

    Tang, Tina Tze-Tsang; Badger, John D; Roche, Paul A; Roche, Katherine W

    2010-07-01

    N-Methyl-d-aspartate (NMDA) receptors are expressed at excitatory synapses throughout the brain and are essential for neuronal development and synaptic plasticity. Functional NMDA receptors are tetramers, typically composed of NR1 and NR2 subunits (NR2A-D). NR2A and NR2B are expressed in the forebrain and are thought to assemble as diheteromers (NR1/NR2A, NR1/NR2B) and triheteromers (NR1/NR2A/NR2B). NR2A and NR2B contain cytosolic domains that regulate distinct postendocytic sorting events, with NR2A sorting predominantly into the degradation pathway, and NR2B preferentially trafficking through the recycling pathway. However, the interplay between these two subunits remains an open question. We have now developed a novel approach based on the dimeric feature of the alpha- and beta-chains of the human major histocompatibility complex class II molecule. We created chimeras of alpha- and beta-chains with the NR2A and NR2B C termini and evaluated endocytosis of dimers. Like chimeric proteins containing only a single NR2A or NR2B C-terminal domain, major histocompatibility complex class II-NR2A homodimers sort predominantly to late endosomes, whereas NR2B homodimers traffic to recycling endosomes. Interestingly, NR2A/NR2B heterodimers traffic preferentially through the recycling pathway, and NR2B is dominant in regulating dimer trafficking in both heterologous cells and neurons. In addition, the recycling of NR2B-containing NMDARs in wild-type neurons is not significantly different from NR2A(-/-) neurons. These data support a dominant role for NR2B in regulating the trafficking of triheteromeric NMDARs in vivo. Furthermore, our molecular approach allows for the direct and selective evaluation of dimeric assemblies and can be used to define dominant trafficking domains in other multisubunit protein complexes. PMID:20427279

  4. Conantokins Derived from the Asprella Clade Impart ConRl-B, an NMDA Receptor Antagonist with a Unique Selectivity Profile for NR2B Subunits

    PubMed Central

    Gowd, Konkallu Hanumae; Han, Tiffany S.; Twede, Vernon; Gajewiak, Joanna; Smith, Misty D.; Watkins, Maren; Platt, Randall J.; Toledo, Gabriela; White, H. Steve; Olivera, Baldomero M.; Bulaj, Grzegorz

    2014-01-01

    Using molecular phylogeny has accelerated the discovery of peptidic ligands targeted to ion channels and receptors. One clade of venomous cone snails, Asprella, appears to be significantly enriched in conantokins, antagonists of N-Methyl D-Asparate receptors (NMDARs). Here, we describe the characterization of two novel conantokins from Conus rolani, including conantokin conRl-B that has shown an unprecedented selectivity for blocking NMDARs that contain NR2B subunits. ConRl-B shares only some sequence similarity to the most studied NR2B-selective conantokin, conG. The divergence between conRl-B and conG in the second inter-Gla loop was used to design analogs for structure-activity studies; the presence of Pro10 was found to be key to the high potency of conRl-B for NR2B, whereas the ε-amino group of Lys8 contributed to discrimination in blocking NR2B- and NR2A-containing NMDARs. In contrast to previous findings from Tyr5 substitutions in other conantokins, conRl-B [L5Y] showed potencies on the four NR2 NMDA receptor subtypes that were similar to those of the native conRl-B. When delivered into the brain, conRl-B was active in suppressing seizures in the model of epilepsy in mice, consistent with NR2B-containing NMDA receptors being potential targets for antiepileptic drugs. Circular dichroism experiments confirmed that the helical conformation of conRl-B is stabilized by divalent metal ions. Given the clinical applications of NMDA antagonists, conRl-B provides a potentially important pharmacological tool for understanding the differential roles of NMDA receptor subtypes in the nervous system. This work shows the effectiveness of coupling molecular phylogeny, chemical synthesis and pharmacology for discovering new bioactive natural products. PMID:22594498

  5. Novel NMDA Receptor Modulators: An Update

    PubMed Central

    Santangelo, Rose M.; Acker, Timothy M.; Zimmerman, Sommer S.; Katzman, Brooke M.; Strong, Katie L.; Traynelis, Stephen F.; Liotta, Dennis C.

    2013-01-01

    Summary Introduction The NMDA receptor is a ligand-gated ion channel that plays a critical role in higher level brain processes and has been implicated in a range of neurological and psychiatric conditions. Although initial studies for the use of NMDA receptor antagonists in neuroprotection were unsuccessful, more recently, NMDA receptor antagonists have shown clinical promise in other indications such as Alzheimer’s disease, Parkinson’s disease, pain and depression. Based on the clinical observations and more recent insights into receptor pharmacology, new modulatory approaches are beginning to emerge, with potential therapeutic benefit. Areas Covered The article covers the known pharmacology and important features regarding NMDA receptors and their function. A discussion of pre-clinical and clinical relevance is included, as well. The subsequent patent literature review highlights the current state of the art targeting the receptor since the last review in 2010. Expert Opinion The complex nature of the NMDA receptor structure and function is becoming better understood. As knowledge about this receptor increases, it opens up new opportunities for targeting the receptor for many therapeutic indications. New strategies and advances in older technologies will need to be further developed before clinical success can be achieved. First-in-class potentiators and subunit-selective agents form the basis for most new strategies, complemented by efforts to limit off-target liability and fine-tune on-target properties. PMID:23009122

  6. Differential contribution of the NR1- and NR2A-subunits to the selectivity filter of recombinant NMDA receptor channels.

    PubMed Central

    Wollmuth, L P; Kuner, T; Seeburg, P H; Sakmann, B

    1996-01-01

    1. The molecular determinants for the narrow constriction of recombinant N-methyl-D-aspartate (NMDA) receptor channels composed of wild-type and mutant NR1- and NR2A-subunits were studied in Xenopus oocytes. 2. The relative permeability of differently sized organic cations was used as an indicator of the size of the narrow constriction. From measured reversal potentials under bi-ionic conditions with K+ as the reference solution, permeability ratios were calculated with the Lewis equation. 3. For wild-type NMDA receptor channels, five organic cations showed clear reversal potentials, with permeability ratios (PX/PK): ammonium, 1.28; methylammonium, 0.48; dimethylammonium (DMA), 0.20; diethylammonium, 0.07; and dimethylethanol-ammonium, 0.02. 4. Mutation of the N-site asparagine (N) to glutamine (Q) at homologous positions in either NR1 (position 598) or NR2A (position 595) increased the permeability of DMA relative to wild-type channels about equally. However, for larger sized organic cations, the NR1(N598Q) mutation had stronger effects on increasing their permeability whereas the NR2A(N595Q) mutation was without effect. These changes in organic cation permeability suggest that the NR1(N598Q) mutation increases the pore size while the NR2A(N595Q) mutation does not. 5. Channels in which the NR1 N-site asparagine was replaced by the smaller glycine (G), NR1(N598G)-NR2A, showed the largest increase in pore size of all sites examined in either subunit. In contrast, in the NR2A-subunit the same N-site substitution to glycine produced only small effects on pore size. 6. For the NR2A-subunit, an asparagine residue (position 596) on the C-terminal side of the N-site, when mutated to larger or smaller sized amino acids, produced large, volume-specific effects on pore size. The mutant channel NR1-NR2A(N596G) had the largest increase in pore size of all sites examined in the NR2A-subunit. In contrast, mutation of the homologous position in the NR1-subunit had no effect on

  7. NMDA receptors and memory encoding.

    PubMed

    Morris, Richard G M

    2013-11-01

    It is humbling to think that 30 years have passed since the paper by Collingridge, Kehl and McLennan showing that one of Jeff Watkins most interesting compounds, R-2-amino-5-phosphonopentanoate (d-AP5), blocked the induction of long-term potentiation in vitro at synapses from area CA3 of the hippocampus to CA1 without apparent effect on baseline synaptic transmission (Collingridge et al., 1983). This dissociation was one of the key triggers for an explosion of interest in glutamate receptors, and much has been discovered since that collectively contributes to our contemporary understanding of glutamatergic synapses - their biophysics and subunit composition, of the agonists and antagonists acting on them, and their diverse functions in different networks of the brain and spinal cord. It can be fairly said that Collingridge et al.'s (1983) observation was the stimulus that has led, on the one hand, to structural biological work at the atomic scale describing the key features of NMDA receptors that enables their coincidence function to happen; and, on the other, to work with whole animals investigating the contributions that calcium signalling via this receptor can have on rhythmical activities controlled by spinal circuits, memory encoding in the hippocampus (the topic of this article), visual cortical plasticity, sensitization in pain, and other functions. In this article, I lay out how my then interest in long-term potentiation (LTP) as a model of memory enabled me to recognise the importance of Collingridge et al.'s discovery - and how I and my colleagues endeavoured to take things forward in the area of learning and memory. This is in some respects a personal story, and I tell it as such. The idea that NMDA receptor activation is essential for memory encoding, though not for storage, took time to develop and to be accepted. Along the way, there have been confusions, challenges, and surprises surrounding the idea that activation of NMDA receptors can

  8. NMDA Receptor Subunits in the Adult Rat Hippocampus Undergo Similar Changes after 5 Minutes in an Open Field and after LTP Induction

    PubMed Central

    Baez, Maria Veronica; Oberholzer, Maria Victoria; Aguirre, Alejandra Ines; Jerusalinsky, Diana Alicia

    2013-01-01

    NMDA receptor subunits change during development and their synaptic expression is modified rapidly after synaptic plasticity induction in hippocampal slices. However, there is scarce information on subunits expression after synaptic plasticity induction or memory acquisition, particularly in adults. GluN1, GluN2A and GluN2B NMDA receptor subunits were assessed by western blot in 1) adult rats that had explored an open field (OF) for 5 minutes, a time sufficient to induce habituation, 2) mature rat hippocampal neuron cultures depolarized by KCl and 3) hippocampal slices from adult rats where long term potentiation (LTP) was induced by theta-burst stimulation (TBS). GluN1 and GluN2A, though not GluN2B, were significantly higher 70 minutes –but not 30 minutes- after a 5 minutes session in an OF. GluN1 and GluN2A total immunofluorescence and puncta in neurites increased in cultures, as evaluated 70 minutes after KCl stimulation. Similar changes were found in hippocampal slices 70 minutes after LTP induction. To start to explore underlying mechanisms, hippocampal slices were treated either with cycloheximide (a translation inhibitor) or actinomycin D (a transcription inhibitor) during electrophysiological assays. It was corroborated that translation was necessary for LTP induction and expression. The rise in GluN1 depends on transcription and translation, while the increase in GluN2A appears to mainly depend on translation, though a contribution of some remaining transcriptional activity during actinomycin D treatment could not be rouled out. LTP effective induction was required for the subunits to increase. Although in the three models same subunits suffered modifications in the same direction, within an apparently similar temporal course, further investigation is required to reveal if they are related processes and to find out whether they are causally related with synaptic plasticity, learning and memory. PMID:23383317

  9. Expression of the NMDA receptor subunit GluN3A (NR3A) in the olfactory system and its regulatory role on olfaction in the adult mouse.

    PubMed

    Lee, Jin Hwan; Wei, Ling; Deveau, Todd C; Gu, Xiaohuan; Yu, Shan Ping

    2016-07-01

    Glutamate is an excitatory neurotransmitter in the olfactory system and its N-methyl-D-aspartate-(NMDA) receptor subunits [GluN1 (NR1), GluN2A (NR2A), and GluN2B (NR2B)] are expressed at synapses in the olfactory bulb and olfactory epithelium. Thus, glutamatergic neurons and NMDA receptors play key roles in olfaction. GluN3A (NR3A) is a unique inhibitory subunit in the NMDA receptor complex; however, the expression and functional role of GluN3A in the olfactory bulb and epithelium remain unclear. The present study examined the expression patterns of GluN3A in the olfactory bulb and epithelium and explored its functional role in the olfactory system. Immunohistochemical and Western blot analyses revealed that GluN3A is abundantly expressed in different cellular layers of the olfactory bulb and epithelium of the adult wild type (WT) mice. In littermate GluN3A knockout (GluN3A(-/-); KO) mice, the expression of olfactory marker protein normally found in mature olfactory sensory neurons was significantly reduced in the olfactory bulb and epithelium. A butyl alcohol stimulus increased immediate-early gene c-Fos expression in the olfactory system of WT mice, while this response was absent in GluN3A KO mice. The level of phosphorylated Ca(2+)/calmodulin-dependent kinase II was significantly lower in GluN3A KO mice compared to WT mice. In buried food finding test, GluN3A mice took significantly longer time to find food compared to WT mice. Consistently, impaired odor distinguishing ability was seen in GluN3A KO mice. These findings suggest that GluN3A, expressed in the adult olfactory system, plays a significant regulatory role in olfactory development and functional activity. PMID:26334321

  10. Differential effects of insufflated, subcutaneous, and intravenous growth hormone on bone growth, cognitive function, and NMDA receptor subunit expression.

    PubMed

    Park, Sung Won; Shin, Sooyoung; Kim, Chi Hwa; Ko, Ah-ra; Kwak, Min Jung; Nam, Mi Hyun; Park, So Young; Kim, Su Jin; Sohn, Young Bae; Galinsky, Raymond E; Kim, Hojoong; Yeo, Yoon; Jin, Dong-Kyu

    2010-09-01

    The objective of this study was to characterize the effect of inhalable growth hormone (GH) delivered by an insufflator to the lungs of hypophysectomized Sprague Dawley rats. In the first cohort, the safety and efficacy of the insufflated GH were evaluated. Three experimental groups (n = 7 per group) were treated with GH for 15 d: One group received sc injection of GH daily at 200 microg/kg (SC200). Two other groups received GH by insufflation daily: 200 microg/kg (INS 200) and 600 microg/kg (INS 600). In the second set of experiments, GH was administered in three routes [SC200, INS200, intravenous (IV200)] (n=10) for 5 d, and escape latency and N-methyl D-aspartate (NMDA) receptor expression were evaluated. In the first cohort, INS200 showed similar bioactivity as SC200 in growth promotion, tibial growth, as well as escape latency on the 12th day of treatment. Insufflated GH was well tolerated without significant inflammatory responses. In the second cohort, expression of the NMDA receptor 1 and 2B in hippocampus measured after 3 or 6 d of daily treatments were significantly higher in INS200 as compared to IV200, consistent with the improvement of the escape latency. In summary, the inhalable form of GH delivered by intratracheal insufflation was safe, and its bioactivity was comparable to sc injection both in promotion of growth and acquisition of learning ability. If applied properly to human, inhalable GH would be effective for growth promotion and possibly for several disorders caused by underexpression of NMDA receptors. PMID:20610568

  11. The N-terminal domain of the GluN3A subunit determines the efficacy of glycine-activated NMDA receptors.

    PubMed

    Mesic, Ivana; Madry, Christian; Geider, Kirsten; Bernhard, Max; Betz, Heinrich; Laube, Bodo

    2016-06-01

    N-methyl-d-aspartate (NMDA) receptors composed of glycine-binding GluN1 and GluN3 subunits function as excitatory glycine receptors that respond to agonist application only with a very low efficacy. Binding of glycine to the high-affinity GluN3 subunits triggers channel opening, whereas glycine binding to the low-affinity GluN1 subunits causes an auto-inhibition of the maximal glycine-inducible receptor current (Imax). Hence, competitive antagonists of the GluN1 subunit strongly potentiate glycine responses of wild type (wt) GluN1/GluN3 receptors. Here, we show that co-expression of N-terminal domain (NTD) deleted GluN1 (GluN1(ΔNTD)) and GluN3 (GluN3(ΔNTD)) subunits in Xenopus oocytes generates GluN1/GluN3 receptors with a large increase in the glycine-inducible Imax accompanied by a strongly impaired GluN1 antagonist-mediated potentiation. Affinity purification after metabolic or surface labeling revealed no differences in subunit stoichiometry and surface expression between wt GluN1/GluN3A and mutant GluN1(ΔNTD)/GluN3A(ΔNTD) receptors, indicating a specific effect of NTD deletions on the efficacy of receptor opening. Notably, GluN1/GluN3A(ΔNTD) receptors showed a similar increase in Imax and a greatly reduced GluN1 antagonist-mediated current potentiation as GluN1(ΔNTD)/GluN3A(ΔNTD) receptors, whereas the glycine-induced currents of GluN1(ΔNTD)/GluN3A receptors resembled those of wt GluN1/GluN3A receptors. Furthermore, oxidative crosslinking of the homophilic GluN3A NTD intersubunit interface in mutant GluN1/GluN3A(R319C) receptors caused both a decrease in the glycine-induced Imax concomitantly with a marked increase in GluN1 antagonist-mediated current potentiation, whilst mutations within the intrasubunit region linking the GluN3A NTD to the ligand binding domain had opposite effects. Together these results show that the GluN3A NTD constitutes a crucial regulatory determinant of GluN1/GluN3A receptor function. PMID:26777280

  12. MPX-004 and MPX-007: New Pharmacological Tools to Study the Physiology of NMDA Receptors Containing the GluN2A Subunit

    PubMed Central

    Volkmann, Robert A.; Fanger, Christopher M.; Anderson, David R.; Sirivolu, Venkata Ramana; Paschetto, Kathy; Gordon, Earl; Virginio, Caterina; Gleyzes, Melanie; Buisson, Bruno; Steidl, Esther; Mierau, Susanna B.; Fagiolini, Michela; Menniti, Frank S.

    2016-01-01

    GluN2A is the most abundant of the GluN2 NMDA receptor subunits in the mammalian CNS. Physiological and genetic evidence implicate GluN2A-containing receptors in susceptibility to autism, schizophrenia, childhood epilepsy and neurodevelopmental disorders such as Rett Syndrome. However, GluN2A-selective pharmacological probes to explore the therapeutic potential of targeting these receptors have been lacking. Here we disclose a novel series of pyrazine-containing GluN2A antagonists exemplified by MPX-004 (5-(((3-chloro-4-fluorophenyl)sulfonamido)methyl)-N-((2-methylthiazol-5-yl)methyl)pyrazine-2-carboxamide) and MPX-007 (5-(((3-fluoro-4-fluorophenyl)sulfonamido)methyl)-N-((2-methylthiazol-5-yl)methyl)methylpyrazine-2-carboxamide). MPX-004 and MPX-007 inhibit GluN2A-containing NMDA receptors expressed in HEK cells with IC50s of 79 nM and 27 nM, respectively. In contrast, at concentrations that completely inhibited GluN2A activity these compounds have no inhibitory effect on GluN2B or GluN2D receptor-mediated responses in similar HEK cell-based assays. Potency and selectivity were confirmed in electrophysiology assays in Xenopus oocytes expressing GluN2A-D receptor subtypes. Maximal concentrations of MPX-004 and MPX-007 inhibited ~30% of the whole-cell current in rat pyramidal neurons in primary culture and MPX-004 inhibited ~60% of the total NMDA receptor-mediated EPSP in rat hippocampal slices. GluN2A-selectivity at native receptors was confirmed by the finding that MPX-004 had no inhibitory effect on NMDA receptor mediated synaptic currents in cortical slices from GRIN2A knock out mice. Thus, MPX-004 and MPX-007 offer highly selective pharmacological tools to probe GluN2A physiology and involvement in neuropsychiatric and developmental disorders. PMID:26829109

  13. MPX-004 and MPX-007: New Pharmacological Tools to Study the Physiology of NMDA Receptors Containing the GluN2A Subunit.

    PubMed

    Volkmann, Robert A; Fanger, Christopher M; Anderson, David R; Sirivolu, Venkata Ramana; Paschetto, Kathy; Gordon, Earl; Virginio, Caterina; Gleyzes, Melanie; Buisson, Bruno; Steidl, Esther; Mierau, Susanna B; Fagiolini, Michela; Menniti, Frank S

    2016-01-01

    GluN2A is the most abundant of the GluN2 NMDA receptor subunits in the mammalian CNS. Physiological and genetic evidence implicate GluN2A-containing receptors in susceptibility to autism, schizophrenia, childhood epilepsy and neurodevelopmental disorders such as Rett Syndrome. However, GluN2A-selective pharmacological probes to explore the therapeutic potential of targeting these receptors have been lacking. Here we disclose a novel series of pyrazine-containing GluN2A antagonists exemplified by MPX-004 (5-(((3-chloro-4-fluorophenyl)sulfonamido)methyl)-N-((2-methylthiazol-5-yl)methyl)pyrazine-2-carboxamide) and MPX-007 (5-(((3-fluoro-4-fluorophenyl)sulfonamido)methyl)-N-((2-methylthiazol-5-yl)methyl)methylpyrazine-2-carboxamide). MPX-004 and MPX-007 inhibit GluN2A-containing NMDA receptors expressed in HEK cells with IC50s of 79 nM and 27 nM, respectively. In contrast, at concentrations that completely inhibited GluN2A activity these compounds have no inhibitory effect on GluN2B or GluN2D receptor-mediated responses in similar HEK cell-based assays. Potency and selectivity were confirmed in electrophysiology assays in Xenopus oocytes expressing GluN2A-D receptor subtypes. Maximal concentrations of MPX-004 and MPX-007 inhibited ~30% of the whole-cell current in rat pyramidal neurons in primary culture and MPX-004 inhibited ~60% of the total NMDA receptor-mediated EPSP in rat hippocampal slices. GluN2A-selectivity at native receptors was confirmed by the finding that MPX-004 had no inhibitory effect on NMDA receptor mediated synaptic currents in cortical slices from GRIN2A knock out mice. Thus, MPX-004 and MPX-007 offer highly selective pharmacological tools to probe GluN2A physiology and involvement in neuropsychiatric and developmental disorders. PMID:26829109

  14. Retention of NMDA receptor NR2 subunits in the lumen of endoplasmic reticulum in targeted NR1 knockout mice

    PubMed Central

    Fukaya, Masahiro; Kato, Akira; Lovett, Chanel; Tonegawa, Susumu; Watanabe, Masahiko

    2003-01-01

    Glutamate is a major excitatory neurotransmitter in the mammalian central nervous system, and the N-methyl-d-aspartate-selective glutamate receptor (NR) consisting of the NR1 subunit and an NR2 or NR3 subunit plays crucial roles in synaptic transmission, plasticity, and learning and memory. By using a knockout mouse strain, in which the NR1 gene deletion is primarily targeted to the CA1 pyramidal cells of the hippocampus, we investigated the in vivo effect of the loss of the NR1 subunit on the cellular expression and intracellular distribution of the NR2 subunits. The NR1 gene deletion had no apparent effect on the levels of NR2A or NR2B mRNA but led to severe reductions of NR2A and NR2B protein in dendrites of CA1 pyramidal cells. This reduced dendritic distribution of the NR2 subunits accompanied their robust accumulation in perikarya, where they were condensed in the lumen of the endoplasmic reticulum as electron-dense granules. These granules were also observed in CA1 pyramidal cells of the control mice but they were much fewer and contained no detectable levels of the NR2 subunit. The effect of the NR1 knockout on intracellular localization of the NR2 subunits was specific in that no such effect was observed for the GluR1 and PSD-95, two other major postsynaptic proteins. These results suggest that the NR1 subunit plays a crucial role in the release of the NR2 subunit from the endoplasmic reticulum in hippocampal pyramidal cells in vivo, and when the NR1 subunit is unavailable, the NR2 subunits are retained and aggregate into intracisternal granules. PMID:12676993

  15. Loss of F-box Only Protein 2 (Fbxo2) Disrupts Levels and Localization of Select NMDA Receptor Subunits, and Promotes Aberrant Synaptic Connectivity

    PubMed Central

    Atkin, Graham; Moore, Shannon; Lu, Yuan; Nelson, Rick F.; Tipper, Nathan; Rajpal, Gautam; Hunt, Jack; Tennant, William; Hell, Johannes W.; Murphy, Geoffrey G.

    2015-01-01

    NMDA receptors (NMDARs) play an essential role in some forms of synaptic plasticity, learning, and memory. Therefore, these receptors are highly regulated with respect to their localization, activation, and abundance both within and on the surface of mammalian neurons. Fundamental questions remain, however, regarding how this complex regulation is achieved. Using cell-based models and F-box Only Protein 2 (Fbxo2) knock-out mice, we found that the ubiquitin ligase substrate adaptor protein Fbxo2, previously reported to facilitate the degradation of the NMDAR subunit GluN1 in vitro, also functions to regulate GluN1 and GluN2A subunit levels in the adult mouse brain. In contrast, GluN2B subunit levels are not affected by the loss of Fbxo2. The loss of Fbxo2 results in greater surface localization of GluN1 and GluN2A, together with increases in the synaptic markers PSD-95 and Vglut1. These synaptic changes do not manifest as neurophysiological differences or alterations in dendritic spine density in Fbxo2 knock-out mice, but result instead in increased axo-dendritic shaft synapses. Together, these findings suggest that Fbxo2 controls the abundance and localization of specific NMDAR subunits in the brain and may influence synapse formation and maintenance. PMID:25878288

  16. Dopamine receptor D5 deficiency results in a selective reduction of hippocampal NMDA receptor subunit NR2B expression and impaired memory.

    PubMed

    Moraga-Amaro, Rodrigo; González, Hugo; Ugalde, Valentina; Donoso-Ramos, Juan Pablo; Quintana-Donoso, Daisy; Lara, Marcelo; Morales, Bernardo; Rojas, Patricio; Pacheco, Rodrigo; Stehberg, Jimmy

    2016-04-01

    Pharmacological evidence associates type I dopamine receptors, including subtypes D1 and D5, with learning and memory. Analyses using genetic approaches have determined the relative contribution of dopamine receptor D1 (D1R) in cognitive tasks. However, the lack of drugs that can discriminate between D1R and D5R has made the pharmacological distinction between the two receptors difficult. Here, we aimed to determine the role of D5R in learning and memory. In this study we tested D5R knockout mice and wild-type littermates in a battery of behavioral tests, including memory, attention, locomotion, anxiety and motivational evaluations. Our results show that genetic deficiency of D5R significantly impairs performance in the Morris water maze paradigm, object location and object recognition memory, indicating a relevant role for D5R in spatial memory and recognition memory. Moreover, the lack of D5R resulted in decreased exploration and locomotion. In contrast, D5R deficiency had no impact on working memory, anxiety and depressive-like behavior, measured using the spontaneous alternation, open-field, tail suspension test, and forced swimming test. Electrophysiological analyses performed on hippocampal slices showed impairment in long-term-potentiation in mice lacking D5R. Further analyses at the molecular level showed that genetic deficiency of D5R results in a strong and selective reduction in the expression of the NMDA receptor subunit NR2B in the hippocampus. These findings demonstrate the relevant contribution of D5R in memory and suggest a functional interaction of D5R with hippocampal glutamatergic pathways. PMID:26714288

  17. Leptin reverses corticosterone-induced inhibition of neural stem cell proliferation through activating the NR2B subunits of NMDA receptors

    SciTech Connect

    Shi, Wen-Zhu; Miao, Yu-Liang; Guo, Wen-Zhi; Wu, Wei; Li, Bao-Wei; An, Li-Na; Fang, Wei-Wu; Mi, Wei-Dong

    2014-04-25

    Highlights: • Leptin promotes the proliferation of neural stem cells isolated from embryonic mouse hippocampus. • Leptin reverses corticosterone-induced inhibition of neural stem cell proliferation. • The effects of leptin are partially mediated by upregulating NR2B subunits. - Abstract: Corticosterone inhibits the proliferation of hippocampal neural stem cells (NSCs). The removal of corticosterone-induced inhibition of NSCs proliferation has been reported to contribute to neural regeneration. Leptin has been shown to regulate brain development, improve angiogenesis, and promote neural regeneration; however, its effects on corticosterone-induced inhibition of NSCs proliferation remain unclear. Here we reported that leptin significantly promoted the proliferation of hippocampal NSCs in a concentration-dependent pattern. Also, leptin efficiently reversed the inhibition of NSCs proliferation induced by corticosterone. Interestingly, pre-treatment with non-specific NMDA antagonist MK-801, specific NR2B antagonist Ro 25-6981, or small interfering RNA (siRNA) targeting NR2B, significantly blocked the effect of leptin on corticosterone-induced inhibition of NSCs proliferation. Furthermore, corticosterone significantly reduced the protein expression of NR2B, whereas pre-treatment with leptin greatly reversed the attenuation of NR2B expression caused by corticosterone in cultured hippocampal NSCs. Our findings demonstrate that leptin reverses the corticosterone-induced inhibition of NSCs proliferation. This process is, at least partially mediated by increased expression of NR2B subunits of NMDA receptors.

  18. GluN2A and GluN2B subunit-containing NMDA receptors in hippocampal plasticity

    PubMed Central

    Shipton, Olivia A.; Paulsen, Ole

    2014-01-01

    N-Methyl-d-aspartate receptor (NMDAR)-dependent synaptic plasticity is a strong candidate to mediate learning and memory processes that require the hippocampus. This plasticity is bidirectional, and how the same receptor can mediate opposite changes in synaptic weights remains a conundrum. It has been suggested that the NMDAR subunit composition could be involved. Specifically, one subunit composition of NMDARs would be responsible for the induction of long-term potentiation (LTP), whereas NMDARs with a different subunit composition would be engaged in the induction of long-term depression (LTD). Unfortunately, the results from studies that have investigated this hypothesis are contradictory, particularly in relation to LTD. Nevertheless, current evidence does suggest that the GluN2B subunit might be particularly important for plasticity and may make a synapse bidirectionally malleable. In particular, we conclude that the presence of GluN2B subunit-containing NMDARs at the postsynaptic density might be a necessary, though not a sufficient, condition for the strengthening of individual synapses. This is owing to the interaction of GluN2B with calcium/calmodulin-dependent protein kinase II (CaMKII) and is distinct from its contribution as an ion channel. PMID:24298164

  19. Hunger States Control the Directions of Synaptic Plasticity via Switching Cell Type-Specific Subunits of NMDA Receptors.

    PubMed

    Qi, Yong; Yang, Yunlei

    2015-09-23

    It remains largely unknown whether and how hunger states control activity-dependent synaptic plasticity, such as long-term potentiation (LTP) and long-term depression (LTD). We here report that both LTP and LTD of excitatory synaptic strength within the appetite control circuits residing in hypothalamic arcuate nucleus (ARC) behave in a manner of hunger states dependence and cell type specificity. For instance, we find that tetanic stimulation induces LTP at orexigenic agouti-related protein (AgRP) neurons in ad libitum fed mice, whereas it induces LTD in food-deprived mice. In an opposite direction, the same induction protocol induces LTD at anorexigenic pro-opiomelanocortin (POMC) neurons in fed mice but weak LTP in deprived mice. Mechanistically, we also find that food deprivation increases the expressions of NR2C/NR2D/NR3-containing NMDA receptors (NMDARs) at AgRP neurons that contribute to the inductions of LTD, whereas it decreases their expressions at POMC neurons. Collectively, our data reveal that hunger states control the directions of activity-dependent synaptic plasticity by switching NMDA receptor subpopulations in a cell type-specific manner, providing insights into NMDAR-mediated interactions between energy states and associative memory. Significance statement: Based on the experiments performed in this study, we demonstrate that activity-dependent synaptic plasticity is also under the control of energy states by regulating NMDAR subpopulations in a cell type-specific manner. We thus propose a reversible memory configuration constructed from energy states-dependent cell type-specific bidirectional conversions of LTP and LTD. Together with the distinct functional roles played by NMDAR signaling in the control of food intake and energy states, these findings reveal a new reciprocal interaction between energy states and associative memory, one that might serve as a target for therapeutic treatments of the energy-related memory disorders or vice versa

  20. NMDA Receptor Function During Senescence: Implication on Cognitive Performance

    PubMed Central

    Kumar, Ashok

    2015-01-01

    N-methyl-D-aspartate (NMDA) receptors, a family of L-glutamate receptors, play an important role in learning and memory, and are critical for spatial memory. These receptors are tetrameric ion channels composed of a family of related subunits. One of the hallmarks of the aging human population is a decline in cognitive function; studies in the past couple of years have demonstrated deterioration in NMDA receptor subunit expression and function with advancing age. However, a direct relationship between impaired memory function and a decline in NMDA receptors is still ambiguous. Recent studies indicate a link between an age-associated NMDA receptor hypofunction and memory impairment and provide evidence that age-associated enhanced oxidative stress might be contributing to the alterations associated with senescence. However, clear evidence is still deficient in demonstrating the underlying mechanisms and a relationship between age-associated impaired cognitive faculties and NMDA receptor hypofunction. The current review intends to present an overview of the research findings regarding changes in expression of various NMDA receptor subunits and deficits in NMDA receptor function during senescence and its implication in age-associated impaired hippocampal-dependent memory function. PMID:26732087

  1. Spinal D1-like dopamine receptors modulate NMDA receptor-induced hyperexcitability and NR1 subunit phosphorylation at serine 889.

    PubMed

    Aira, Zigor; Barrenetxea, Teresa; Buesa, Itsaso; Martínez, Endika; Azkue, Jon Jatsu

    2016-04-01

    Activation of the N-methyl-d-aspartate receptor (NMDAR) in dorsal horn neurons is recognized as a fundamental mechanism of central sensitization and pathologic pain. This study assessed the influence of dopaminergic, D1-like receptor-mediated input to the spinal dorsal horn on NMDAR function. PMID:26957228

  2. NMDA Receptors Mediate Synaptic Competition in Culture

    PubMed Central

    She, Kevin; Craig, Ann Marie

    2011-01-01

    Background Activity through NMDA type glutamate receptors sculpts connectivity in the developing nervous system. This topic is typically studied in the visual system in vivo, where activity of inputs can be differentially regulated, but in which individual synapses are difficult to visualize and mechanisms governing synaptic competition can be difficult to ascertain. Here, we develop a model of NMDA-receptor dependent synaptic competition in dissociated cultured hippocampal neurons. Methodology/Principal Findings GluN1 -/- (KO) mouse hippocampal neurons lacking the essential NMDA receptor subunit were cultured alone or cultured in defined ratios with wild type (WT) neurons. The absence of functional NMDA receptors did not alter neuron survival. Synapse development was assessed by immunofluorescence for postsynaptic PSD-95 family scaffold and apposed presynaptic vesicular glutamate transporter VGlut1. Synapse density was specifically enhanced onto minority wild type neurons co-cultured with a majority of GluN1 -/- neighbour neurons, both relative to the GluN1 -/- neighbours and relative to sister pure wild type cultures. This form of synaptic competition was dependent on NMDA receptor activity and not conferred by the mere physical presence of GluN1. In contrast to these results in 10% WT and 90% KO co-cultures, synapse density did not differ by genotype in 50% WT and 50% KO co-cultures or in 90% WT and 10% KO co-cultures. Conclusions/Significance The enhanced synaptic density onto NMDA receptor-competent neurons in minority coculture with GluN1 -/- neurons represents a cell culture paradigm for studying synaptic competition. Mechanisms involved may include a retrograde ‘reward’ signal generated by WT neurons, although in this paradigm there was no ‘punishment’ signal against GluN1 -/- neurons. Cell culture assays involving such defined circuits may help uncover the rules and mechanisms of activity-dependent synaptic competition in the developing nervous

  3. Developmental Changes in NMDA Receptor Subunit Composition at ON and OFF Bipolar Cell Synapses onto Direction-Selective Retinal Ganglion Cells

    PubMed Central

    Stafford, Benjamin K.; Park, Silvia J. H.; Wong, Kwoon Y.

    2014-01-01

    In the developing mouse retina, spontaneous and light-driven activity shapes bipolar→ganglion cell glutamatergic synapse formation, beginning around the time of eye-opening (P12–P14) and extending through the first postnatal month. During this time, glutamate release can spill outside the synaptic cleft and possibly stimulate extrasynaptic NMDA-type glutamate receptors (NMDARs) on ganglion cells. Furthermore, the role of NMDARs during development may differ between ON and OFF bipolar synapses as in mature retina, where ON synapses reportedly include extrasynaptic NMDARs with GluN2B subunits. To better understand the function of glutamatergic synapses during development, we made whole-cell recordings of NMDAR-mediated responses, in vitro, from two types of genetically identified direction-selective ganglion cells (dsGCs): TRHR (thyrotropin-releasing hormone receptor) and Drd4 (dopamine receptor 4). Both dsGC types responded to puffed NMDA between P7 and P28; and both types exhibited robust light-evoked NMDAR-mediated responses at P14 and P28 that were quantified by conductance analysis during nicotinic and GABAA receptor blockade. For a given cell type and at a given age, ON and OFF bipolar cell inputs evoked similar NMDAR-mediated responses, suggesting that ON-versus-OFF differences in mature retina do not apply to the cell types or ages studied here. At P14, puff- and light-evoked NMDAR-mediated responses in both dsGCs were partially blocked by the GluN2B antagonist ifenprodil, whereas at P28 only TRHR cells remained ifenprodil-sensitive. NMDARs contribute at both ON and OFF bipolar cell synapses during a period of robust activity-dependent synaptic development, with declining GluN2B involvement over time in specific ganglion cell types. PMID:24478373

  4. Fyn Kinase regulates GluN2B subunit-dominant NMDA receptors in human induced pluripotent stem cell-derived neurons

    PubMed Central

    Zhang, Wen-Bo; Ross, P. Joel; Tu, YuShan; Wang, Yongqian; Beggs, Simon; Sengar, Ameet S.; Ellis, James; Salter, Michael W.

    2016-01-01

    NMDA receptor (NMDAR)-mediated fast excitatory neurotransmission is implicated in a broad range of physiological and pathological processes in the mammalian central nervous system. The function and regulation of NMDARs have been extensively studied in neurons from rodents and other non-human species, and in recombinant expression systems. Here, we investigated human NMDARs in situ by using neurons produced by directed differentiation of human induced pluripotent stem cells (iPSCs). The resultant cells showed electrophysiological characteristics demonstrating that they are bona fide neurons. In particular, human iPSC-derived neurons expressed functional ligand-gated ion channels, including NMDARs, AMPA receptors, GABAA receptors, as well as glycine receptors. Pharmacological and electrophysiological properties of NMDAR-mediated currents indicated that these were dominated by receptors containing GluN2B subunits. The NMDAR currents were suppressed by genistein, a broad-spectrum tyrosine kinase inhibitor. The NMDAR currents were also inhibited by a Fyn-interfering peptide, Fyn(39–57), but not a Src-interfering peptide, Src(40–58). Together, these findings are the first evidence that tyrosine phosphorylation regulates the function of NMDARs in human iPSC-derived neurons. Our findings provide a basis for utilizing human iPSC-derived neurons in screening for drugs targeting NMDARs in neurological disorders. PMID:27040756

  5. NMDA receptor antibodies

    PubMed Central

    Ramberger, Melanie; Bsteh, Gabriel; Schanda, Kathrin; Höftberger, Romana; Rostásy, Kevin; Baumann, Matthias; Aboulenein-Djamshidian, Fahmy; Lutterotti, Andreas; Deisenhammer, Florian; Berger, Thomas

    2015-01-01

    Objectives: To analyze the frequency of NMDA receptor (NMDAR) antibodies in patients with various inflammatory demyelinating diseases of the CNS and to determine their clinical correlates. Methods: Retrospective case-control study from 2005 to 2014 with the detection of serum IgG antibodies to NMDAR, aquaporin-4, and myelin oligodendrocyte glycoprotein by recombinant live cell-based immunofluorescence assays. Fifty-one patients with acute disseminated encephalomyelitis, 41 with neuromyelitis optica spectrum disorders, 34 with clinically isolated syndrome, and 89 with multiple sclerosis (MS) were included. Due to a known association of NMDAR antibodies with seizures and behavioral symptoms, patients with those clinical manifestations were preferentially included and are therefore overrepresented in our cohort. Nine patients with NMDAR encephalitis, 94 patients with other neurologic diseases, and 48 healthy individuals were used as controls. Results: NMDAR antibodies were found in all 9 patients with NMDAR encephalitis but in only 1 of 215 (0.5%) patients with inflammatory demyelination and in none of the controls. This patient had relapsing-remitting MS with NMDAR antibodies present at disease onset, with an increase in NMDAR antibody titer with the onset of psychiatric symptoms and cognitive deficits. Conclusion: In demyelinating disorders, NMDAR antibodies are uncommon, even in those with symptoms seen in NMDAR encephalitis. PMID:26309901

  6. Bisphenol-A rapidly enhanced passive avoidance memory and phosphorylation of NMDA receptor subunits in hippocampus of young rats

    SciTech Connect

    Xu Xiaohong Li Tao; Luo Qingqing; Hong Xing; Xie Lingdan; Tian Dong

    2011-09-01

    Bisphenol-A (BPA), an endocrine disruptor, is found to influence development of brain and behaviors in rodents. The previous study indicated that perinatal exposure to BPA impaired learning-memory and inhibited N-methyl-D-aspartate receptor (NMDAR) subunits expressions in hippocampus during the postnatal development in rats; and in cultured hippocampal neurons, BPA rapidly promotes dynamic changes in dendritic morphology through estrogen receptor-mediated pathway by concomitant phosphorylation of NMDAR subunit NR2B. In the present study, we examined the rapid effect of BPA on passive avoidance memory and NMDAR in the developing hippocampus of Sprague-Dawley rats at the age of postnatal day 18. The results showed that BPA or estradiol benzoate (EB) rapidly extended the latency to step down from the platform 1 h after footshock and increased the phosphorylation levels of NR1, NR2B, and mitogen-activated extracellular signal-regulated kinase (ERK) in hippocampus within 1 h. While 24 h after BPA or EB treatment, the improved memory and the increased phosphorylation levels of NR1, NR2B, ERK disappeared. Furthermore, pre-treatment with an estrogen receptors (ERs) antagonist, ICI182,780, or an ERK-activating kinase inhibitor, U0126, significantly attenuated EB- or BPA-induced phosphorylations of NR1, NR2B, and ERK within 1 h. These data suggest that BPA rapidly enhanced short-term passive avoidance memory in the developing rats. A non-genomic effect via ERs may mediate the modulation of the phosphorylation of NMDAR subunits NR1 and NR2B through ERK signaling pathway. - Highlights: > BPA rapidly extended the latency to step down from platform 1 h after footshock. > BPA rapidly increased pNR1, pNR2B, and pERK in hippocampus within 1 h. > ERs antagonist or MEK inhibitor attenuated BPA-induced pNR1, pNR2B, and pERK.

  7. Morphine-Induced Analgesic Tolerance Effect on Gene Expression of the NMDA Receptor Subunit 1 in Rat Striatum and Prefrontal Cortex

    PubMed Central

    Ahmadi, Shamseddin; Rafieenia, Fatemeh; Rostamzadeh, Jalal

    2016-01-01

    Introduction: Morphine is a potent analgesic but its continual use results in analgesic tolerance. Mechanisms of this tolerance remain to be clarified. However, changes in the functions of μ-opioid and N-Methyl-D-aspartate (NMDA) receptors have been proposed in morphine tolerance. We examined changes in gene expression of the NMDA receptor subunit 1 (NR1) at mRNA levels in rat striatum and prefrontal cortex (PFC) after induction of morphine tolerance. Methods: Morphine (10 mg/kg, IP) was injected in male Wistar rats for 7 consecutive days (intervention group), but control rats received just normal saline (1 mL/kg, IP). We used a hotplate test of analgesia to assess induction of tolerance to analgesic effects of morphine on days 1 and 8 of injections. Later, two groups of rats were sacrificed one day after 7 days of injections, their whole brains removed, and the striatum and PFC immediately dissected. Then, the NR1 gene expression was examined with a semi-quantitative RT-PCR method. Results: The results showed that long-term morphine a administration induces tolerance to analgesic effect of the opioid, as revealed by a significant decrease in morphine-induced analgesia on day 8 compared to day 1 of the injections (P<0.001). The results also showed that the NR1 gene expression at mRNA level in rats tolerant to morphine was significantly increased in the striatum (P<0.01) but decreased in the PFC (P<0.001). Conclusion: Therefore, changes in the NR1 gene expression in rat striatum and PFC have a region-specific association with morphine-induced analgesic tolerance. PMID:27563417

  8. A family of photoswitchable NMDA receptors

    PubMed Central

    Berlin, Shai; Szobota, Stephanie; Reiner, Andreas; Carroll, Elizabeth C; Kienzler, Michael A; Guyon, Alice; Xiao, Tong; Tauner, Dirk; Isacoff, Ehud Y

    2016-01-01

    NMDA receptors, which regulate synaptic strength and are implicated in learning and memory, consist of several subtypes with distinct subunit compositions and functional properties. To enable spatiotemporally defined, rapid and reproducible manipulation of function of specific subtypes, we engineered a set of photoswitchable GluN subunits ('LiGluNs'). Photo-agonism of GluN2A or GluN2B elicits an excitatory drive to hippocampal neurons that can be shaped in time to mimic synaptic activation. Photo-agonism of GluN2A at single dendritic spines evokes spine-specific calcium elevation and expansion, the morphological correlate of LTP. Photo-antagonism of GluN2A alone, or in combination with photo-antagonism of GluN1a, reversibly blocks excitatory synaptic currents, prevents the induction of long-term potentiation and prevents spine expansion. In addition, photo-antagonism in vivo disrupts synaptic pruning of developing retino-tectal projections in larval zebrafish. By providing precise and rapidly reversible optical control of NMDA receptor subtypes, LiGluNs should help unravel the contribution of specific NMDA receptors to synaptic transmission, integration and plasticity. DOI: http://dx.doi.org/10.7554/eLife.12040.001 PMID:26929991

  9. A family of photoswitchable NMDA receptors.

    PubMed

    Berlin, Shai; Szobota, Stephanie; Reiner, Andreas; Carroll, Elizabeth C; Kienzler, Michael A; Guyon, Alice; Xiao, Tong; Tauner, Dirk; Isacoff, Ehud Y

    2016-01-01

    NMDA receptors, which regulate synaptic strength and are implicated in learning and memory, consist of several subtypes with distinct subunit compositions and functional properties. To enable spatiotemporally defined, rapid and reproducible manipulation of function of specific subtypes, we engineered a set of photoswitchable GluN subunits ('LiGluNs'). Photo-agonism of GluN2A or GluN2B elicits an excitatory drive to hippocampal neurons that can be shaped in time to mimic synaptic activation. Photo-agonism of GluN2A at single dendritic spines evokes spine-specific calcium elevation and expansion, the morphological correlate of LTP. Photo-antagonism of GluN2A alone, or in combination with photo-antagonism of GluN1a, reversibly blocks excitatory synaptic currents, prevents the induction of long-term potentiation and prevents spine expansion. In addition, photo-antagonism in vivo disrupts synaptic pruning of developing retino-tectal projections in larval zebrafish. By providing precise and rapidly reversible optical control of NMDA receptor subtypes, LiGluNs should help unravel the contribution of specific NMDA receptors to synaptic transmission, integration and plasticity. PMID:26929991

  10. Conserved Expression of the Glutamate NMDA Receptor 1 Subunit Splice Variants during the Development of the Siberian Hamster Suprachiasmatic Nucleus

    PubMed Central

    Duffield, Giles E.; Mikkelsen, Jens D.; Ebling, Francis J. P.

    2012-01-01

    Glutamate neurotransmission and the N-methyl-D-aspartate receptor (NMDAR) are central to photic signaling to the master circadian pacemaker located in the hypothalamic suprachiasmatic nucleus (SCN). NMDARs also play important roles in brain development including visual input circuits. The functional NMDAR is comprised of multiple subunits, but each requiring the NR1 subunit for normal activity. The NR1 can be alternatively spliced to produce isoforms that confer different functional properties on the NMDAR. The SCN undergoes extensive developmental changes during postnatal life, including synaptogenesis and acquisition of photic signaling. These changes are especially important in the highly photoperiodic Siberian hamster, in which development of sensitivity to photic cues within the SCN could impact early physiological programming. In this study we examined the expression of NR1 isoforms in the hamster at different developmental ages. Gene expression in the forebrain was quantified by in situ hybridization using oligonucleotide probes specific to alternatively spliced regions of the NR1 heteronuclear mRNA, including examination of anterior hypothalamus, piriform cortex, caudate-putamen, thalamus and hippocampus. Gene expression analysis within the SCN revealed the absence of the N1 cassette, the presence of the C2 cassette alone and the combined absence of C1 and C2 cassettes, indicating that the dominant splice variants are NR1-2a and NR1-4a. Whilst we observe changes at different developmental ages in levels of NR1 isoform probe hybridization in various forebrain structures, we find no significant changes within the SCN. This suggests that a switch in NR1 isoform does not underlie or is not produced by developmental changes within the hamster SCN. Consistency of the NR1 isoforms would ensure that the response of the SCN cells to photic signals remains stable throughout life, an important aspect of the function of the SCN as a responder to environmental changes

  11. Neonatal seizures alter NMDA glutamate receptor GluN2A and 3A subunit expression and function in hippocampal CA1 neurons.

    PubMed

    Zhou, Chengwen; Sun, Hongyu; Klein, Peter M; Jensen, Frances E

    2015-01-01

    Neonatal seizures are commonly caused by hypoxic and/or ischemic injury during birth and can lead to long-term epilepsy and cognitive deficits. In a rodent hypoxic seizure (HS) model, we have previously demonstrated a critical role for seizure-induced enhancement of the AMPA subtype of glutamate receptor (GluA) in epileptogenesis and cognitive consequences, in part due to GluA maturational upregulation of expression. Similarly, as the expression and function of the N-Methyl-D-aspartate (NMDA) subtype of glutamate receptor (GluN) is also developmentally controlled, we examined how early life seizures during the critical period of synaptogenesis could modify GluN development and function. In a postnatal day (P)10 rat model of neonatal seizures, we found that seizures could alter GluN2/3 subunit composition of GluNs and physiological function of synaptic GluNs. In hippocampal slices removed from rats within 48-96 h following seizures, the amplitudes of synaptic GluN-mediated evoked excitatory postsynaptic currents (eEPSCs) were elevated in CA1 pyramidal neurons. Moreover, GluN eEPSCs showed a decreased sensitivity to GluN2B selective antagonists and decreased Mg(2+) sensitivity at negative holding potentials, indicating a higher proportion of GluN2A and GluN3A subunit function, respectively. These physiological findings were accompanied by a concurrent increase in GluN2A phosphorylation and GluN3A protein. These results suggest that altered GluN function and expression could potentially contribute to future epileptogenesis following neonatal seizures, and may represent potential therapeutic targets for the blockade of future epileptogenesis in the developing brain. PMID:26441533

  12. Reducing expression of GluN1(0XX) subunit splice variants of the NMDA receptor interferes with spatial reference memory.

    PubMed

    Das, Siba R; Jensen, Ross; Kelsay, Rian; Shumaker, Michelle; Bochart, Rachele; Brim, Brenna; Zamzow, Daniel; Magnusson, Kathy R

    2012-05-01

    The GluN1 subunit of the N-methyl-D-aspartate (NMDA) receptor shows age-related changes in its expression pattern, some of which correlate with spatial memory performance in mice. Aged C57BL/6 mice show an age-related increase in mRNA expression of GluN1 subunit splice variants that lack the N terminal splice cassette, GluN1(0XX) (GluN1-a). This increase in expression is associated with good performance in reference and working memory tasks. The present study was undertaken to determine if GluN1(0XX) splice variants are required for good performance in reference memory tasks in young mice. Mice were bilaterally injected with either siRNA specific for GluN1(0XX) splice variants, control siRNA or vehicle alone into ventro-lateral orbital cortices. A fourth group of mice did not receive any injections. Starting five days post-injection, mice were tested for their performance in spatial reference memory, associative memory and cognitive flexibility tasks over four days in the Morris water maze. There was a 10-19% reduction in mRNA expression for GluN1(0XX) splice variants within the ventro-lateral orbital cortices in mice following GluN1(0XX) siRNA treatment. Declines in performance within the first half of reference memory testing were seen in the mice receiving siRNA against the GluN1(0XX) splice variants, as compared to the mice injected with control siRNA, vehicle and/or no treatment. These results suggest a role for the GluN1(0XX) splice variants in orbital regions for early acquisition and/or consolidation of spatial reference memory. PMID:22360858

  13. Chronic brain inflammation causes a reduction in GluN2A and GluN2B subunits of NMDA receptors and an increase in the phosphorylation of mitogen-activated protein kinases in the hippocampus

    PubMed Central

    2014-01-01

    Neuroinflammation plays a key role in the initiation and progression of neurodegeneration in Alzheimer’s disease (AD). Chronic neuroinflammation results in diminished synaptic plasticity and loss of GluN1 N-methyl-D-aspartate (NMDA) receptors in the hippocampus, leading to the cognitive deficits that are the most common symptoms of AD. Therefore, it is suggested that chronic inflammation may alter expression levels of GluN2A and GluN2B subunits of NMDA receptors and associated intracellular signalling. Chronic neuroinflammation was induced by chronic infusion of lipopolysaccharide (LPS) into the fourth ventricle in Fischer-344 rats. The status of hippocampus-dependent memory was evaluated in control rats and rats chronically infused with LPS. Microglial activation in the hippocampus was examined using immunohistochemical staining. Western blot analysis was used to measure membrane levels of GluN2A and GluN2B subunits of NMDA receptors and mitogen-activated protein kinase (MAPK) in the hippocampi of these rats, and immunofluorescent double labeling was used to assess the cellular location of MAPK. Microglial activation was observed in the hippocampi of rats that showed memory impairments with chronic LPS infusion. Chronic LPS infusion reduced the levels of GluN2A and GluN2B and increased the levels of phosphorylated MAPKs in the hippocampus. MAPK-positive immunoreactivity was observed mostly in the neurons and also in non-neuronal cells. Reductions in GluN2A and GluN2B subunits of NMDA receptors coupled with altered MAPK signaling, in response to inflammatory stimuli may be related to the cognitive deficits observed in AD. PMID:24761931

  14. Amyloid β peptide oligomers directly activate NMDA receptors.

    PubMed

    Texidó, Laura; Martín-Satué, Mireia; Alberdi, Elena; Solsona, Carles; Matute, Carlos

    2011-03-01

    Amyloid beta (Aβ) oligomers accumulate in the brain tissue of Alzheimer disease patients and are related to disease pathogenesis. The precise mechanisms by which Aβ oligomers cause neurotoxicity remain unknown. We recently reported that Aβ oligomers cause intracellular Ca(2+) overload and neuronal death that can be prevented by NMDA receptor antagonists. This study investigated whether Aβ oligomers directly activated NMDA receptors (NMDARs) using NR1/NR2A and NR1/NR2B receptors that were heterologously expressed in Xenopus laevis oocytes. Indeed, Aβ oligomers induced inward non-desensitizing currents that were blocked in the presence of the NMDA receptor antagonists memantine, APV, and MK-801. Intriguingly, the amplitude of the responses to Aβ oligomers was greater for NR1/NR2A heteromers than for NR1/NR2B heteromers expressed in oocytes. Consistent with these findings, we observed that the increase in the cytosolic concentration of Ca(2+) induced by Aβ oligomers in cortical neurons is prevented by AP5, a broad spectrum NMDA receptor antagonist, but slightly attenuated by ifenprodil which blocks receptors with the NR2B subunit. Together, these results indicate that Aβ oligomers directly activate NMDA receptors, particularly those with the NR2A subunit, and further suggest that drugs that attenuate the activity of such receptors may prevent Aβ damage to neurons in Alzheimeŕs disease. PMID:21349580

  15. Nuclear respiratory factor 2 regulates the expression of the same NMDA receptor subunit genes as NRF-1: Both factors act by a concurrent and parallel mechanism to couple energy metabolism and synaptic transmission

    PubMed Central

    Priya, Anusha; Johar, Kaid; Wong-Riley, Margaret

    2012-01-01

    Neuronal activity and energy metabolism are tightly coupled processes. Previously, we found that nuclear respiratory factor 1 (NRF-1) transcriptionally co-regulates energy metabolism and neuronal activity by regulating all 13 subunits of the critical energy generating enzyme, cytochrome c oxidase (COX), as well as GluN1 (Grin1) and GluN2B (Grin2b) subunits of NMDA receptors. We also found that another transcription factor, nuclear respiratory factor 2 (NRF-2 or GA-binding protein) regulates all subunits of COX as well. The goal of the present study was to test our hypothesis that NRF-2 also regulates specific subunits of NMDA receptors, and that it functions with NRF-1 via one of three mechanisms: complementary, concurrent and parallel, or a combination of complementary and concurrent/parallel. By means of multiple approaches, including in silico analysis, electrophoretic mobility shift and supershift assays, in vivo chromatin immunoprecipitation of mouse neuroblastoma cells and rat visual cortical tissue, promoter mutations, real-time quantitative PCR, and western blot analysis, NRF-2 was found to functionally regulate Grin1 and Grin2b genes, but not any other NMDA subunit genes. Grin1 and Grin2b transcripts were up-regulated by depolarizing KCl, but silencing of NRF-2 prevented this up-regulation. On the other hand, over-expression of NRF-2 rescued the down-regulation of these subunits by the impulse blocker TTX. NRF-2 binding sites on Grin1 and Grin2b are conserved among species. Our data indicate that NRF-2 and NRF-1 operate in a concurrent and parallel manner in mediating the tight coupling between energy metabolism and neuronal activity at the molecular level. PMID:23085505

  16. Nuclear respiratory factor 2 regulates the expression of the same NMDA receptor subunit genes as NRF-1: both factors act by a concurrent and parallel mechanism to couple energy metabolism and synaptic transmission.

    PubMed

    Priya, Anusha; Johar, Kaid; Wong-Riley, Margaret T T

    2013-01-01

    Neuronal activity and energy metabolism are tightly coupled processes. Previously, we found that nuclear respiratory factor 1 (NRF-1) transcriptionally co-regulates energy metabolism and neuronal activity by regulating all 13 subunits of the critical energy generating enzyme, cytochrome c oxidase (COX), as well as N-methyl-d-aspartate (NMDA) receptor subunits 1 and 2B, GluN1 (Grin1) and GluN2B (Grin2b). We also found that another transcription factor, nuclear respiratory factor 2 (NRF-2 or GA-binding protein) regulates all subunits of COX as well. The goal of the present study was to test our hypothesis that NRF-2 also regulates specific subunits of NMDA receptors, and that it functions with NRF-1 via one of three mechanisms: complementary, concurrent and parallel, or a combination of complementary and concurrent/parallel. By means of multiple approaches, including in silico analysis, electrophoretic mobility shift and supershift assays, in vivo chromatin immunoprecipitation of mouse neuroblastoma cells and rat visual cortical tissue, promoter mutations, real-time quantitative PCR, and western blot analysis, NRF-2 was found to functionally regulate Grin1 and Grin2b genes, but not any other NMDA subunit genes. Grin1 and Grin2b transcripts were up-regulated by depolarizing KCl, but silencing of NRF-2 prevented this up-regulation. On the other hand, over-expression of NRF-2 rescued the down-regulation of these subunits by the impulse blocker TTX. NRF-2 binding sites on Grin1 and Grin2b are conserved among species. Our data indicate that NRF-2 and NRF-1 operate in a concurrent and parallel manner in mediating the tight coupling between energy metabolism and neuronal activity at the molecular level. PMID:23085505

  17. [Anti-NMDA-receptor encephalitis].

    PubMed

    Engen, Kristine; Agartz, Ingrid

    2016-06-01

    BACKGROUND In 2007 a clinical disease caused by autoantibodies directed against the N-methyl-D-aspartate (NMDA) receptor was described for the first time. Anti-NMDA-receptor encephalitis is a subacute, autoimmune neurological disorder with psychiatric manifestations. The disease is a form of limbic encephalitis and is often paraneoplastic. The condition is also treatable. In this review article we examine the development of the disease, clinical practice, diagnostics and treatment.MATERIAL AND METHOD The article is based on references retrieved from searches in PubMed, and a discretionary selection of articles from the authors' own literature archive.RESULTS The disease most frequently affects young women. It may initially be perceived as a psychiatric condition, as it usually presents in the form of delusions, hallucinations or mania. The diagnosis should be suspected in patients who later develop neurological symptoms such as various movement disorders, epileptic seizures and autonomic instability. Examination of serum or cerebrospinal fluid for NMDA receptor antibodies should be included in the assessment of patients with suspected encephalitis. MRI, EEG and assessment for tumours are important tools in diagnosing the condition and any underlying malignancy.INTERPRETATION If treatment is initiated early, the prognosis is good. Altogether 75 % of patients will fully recover or experience significant improvement. Apart from surgical resection of a possible tumour, the treatment consists of immunotherapy. Because of good possibilities for treatment, it is important that clinicians, particularly those in acute psychiatry, are aware of and alert to this condition. PMID:27325034

  18. Effects of sex and chronic neonatal nicotine treatment on Na²⁺/K⁺/Cl⁻ co-transporter 1, K⁺/Cl⁻ co-transporter 2, brain-derived neurotrophic factor, NMDA receptor subunit 2A and NMDA receptor subunit 2B mRNA expression in the postnatal rat hippocampus.

    PubMed

    Damborsky, J C; Winzer-Serhan, U H

    2012-12-01

    Chronic exposure to nicotine during the first postnatal week in rats, a developmental period that corresponds to the third trimester of human gestation, results in sexually dimorphic long-term functional defects in the adult hippocampus. One potential cause could be the sex-specific differences in the maturation of GABA(A) receptor-mediated responses from excitatory to inhibitory, which depends on the expression of the Na(2+)/K(+)/Cl(-) co-transporter 1 (NKCC1) and the K(+)/Cl(-) co-transporter 2 (KCC2). In the rat hippocampus, this switch occurs during the first and second postnatal week in females and males, respectively, and is regulated by nicotinic receptor activation. Excitatory GABAergic signaling can increase brain-derived neurotrophic factor (BDNF) expression, which might exacerbate sex differences by impacting synaptogenesis. We hypothesized that chronic neonatal nicotine (CNN) exposure differentially regulates the expression of these co-transporters and BDNF in males and females. We use quantitative isotopic in situ hybridization to examine the expression of mRNAs for NKCC1, KCC2, BDNF, and NMDA receptor subunit 2A (NR2A) and NMDA receptor subunit 2B (NR2B) in the postnatal day (P) 5 and 8 rat hippocampi in both sexes that were either control-treated or with 6mg/kg/day nicotine in milk formula (CNN) via gastric intubation starting at P1. In line with prolonged GABAergic excitation, we found that at P5 males had significantly higher mRNA expression of NKCC1 and BDNF than females. CNN treatment resulted in a significant increase in KCC2 and BDNF mRNA expression in male but not female hippocampus (p<0.05). Males also had higher expression of NR2A and lower expression of NR2B at P5 compared to females (p<0.05). At P8, there were neither sex nor treatment effects on mRNA expression, indicating the end of a critical period for sensitivity to nicotine. These results suggest that differential maturation of GABA(A)R-mediated responses result in sex

  19. Hepatic encephalopathy induces site-specific changes in gene expression of GluN1 subunit of NMDA receptor in rat brain.

    PubMed

    Ahmadi, Shamseddin; Poureidi, Mahsa; Rostamzadeh, Jalal

    2015-08-01

    We investigate changes in gene expression of GluN1 subunit of N-Methyl-D-Aspartate (NMDA) receptor in the prefrontal cortex (PFC), hippocampus and striatum in a rat model of hepatic encephalopathy (HE). We used male Wistar rats in which HE was induced after a common bile duct ligation (BDL). The animals were divided into three sets, and each set included three groups of control, sham operated and BDL. In the first set of animals, blood samples collected for biochemical analysis on day 21 of BDL. In the second set, changes in nociception threshold was assessed on day 21 of BDL using a hotplate test. In the third set, whole brain extracted, and the PFC, the hippocampus and the striatum in each rat were immediately dissected. We used a semi-quantitative RT-PCR method for evaluating the GluN1 gene expression. The biochemical analyses showed that plasma levels of ammonia and bilirubin in BDL rats were significantly increased compared to the sham control group on day 21 of BDL (P < 0.01). Nociception threshold was also increased in rats with BDL compared to sham group (P < 0.001). The results revealed that the GluN1 gene expression at mRNA levels in BDL group was decreased by 19 % in the PFC (P < 0.05) but increased by 82 % in the hippocampus (P < 0.01) compared to the sham control group; however, no significant change was observed in the striatum. It can be concluded that HE affects the GluN1 gene expression in rat brain with a site-specific pattern, and the PFC and hippocampus are more sensitive areas than striatum. PMID:25896221

  20. Developmental changes in NMDA receptor expression in the platyfish brain

    NASA Technical Reports Server (NTRS)

    Flynn, K. M.; Schreibman, M. P.; Magliulo-Cepriano, L.

    1997-01-01

    We have examined the distribution of the N-methyl-D-aspartate (NMDA) receptor in the brain of a freshwater teleost using an antibody against the R1 subunit of the receptor (NMDAR1). The primary site of localization was the nucleus olfactoretinalis (NOR), a significant gonadotropin releasing hormone (GnRH)-containing brain nucleus. The number of cells expressing NMDAR1 in this nucleus was dependent upon developmental stage, with pubescent and mature animals displaying significantly more stained cells than immature and senescent animals. This is the first reported observation of age- and maturity-related NMDA receptor association with GnRH-containing brain areas.

  1. Dual contribution of NR2B subunit of NMDA receptor and SK3 Ca(2+)-activated K+ channel to genetic predisposition to anorexia nervosa.

    PubMed

    Koronyo-Hamaoui, Maya; Frisch, Amos; Stein, Daniel; Denziger, Yardena; Leor, Shani; Michaelovsky, Elena; Laufer, Neil; Carel, Cynthia; Fennig, Silvana; Mimouni, Mark; Ram, Anca; Zubery, Eynat; Jeczmien, Pablo; Apter, Alan; Weizman, Abraham; Gak, Eva

    2007-01-01

    Since identification of the genetic component in anorexia nervosa (AN), genes that partake in serotonergic and dopaminergic systems and in hormonal and weight regulation have been suggested as potential candidates for AN susceptibility. We propose another set of candidate genes. Those are genes that are involved in the signaling pathway using NMDA-R and SK channels and have been suggested as possible effectors of NMDA-R driven signaling. The role of NMDA-R in the etiology of schizophrenia has already been substantiated on various levels. Several studies based on population and family groups have implicated SK3 in schizophrenia and more recently in AN as well. Our study group consisted of 90 AN family trios. We examined the transmission of two potentially functional polymorphisms, 5073T>G polymorphism in the gene encoding the NR2B subunit of NMDA-R and CAG repeats in the coding region of SK3 channel gene. Using HHRR and TDT approaches, we found that both polymorphisms were preferentially transmitted to AN offspring (TDT yielded chi(2)=5.01, p=0.025 for NR2B 5073G alleles and chi(2)=11.75, p<0.001 for SK3 L alleles including >19 repeats). Distribution analysis of the combined NR2B/SK3 genotypes suggests that the contribution of both polymorphisms to AN risk is independent and cumulative (OR=2.44 for NR2B GG genotype and OR=3.01 for SK3 SL and LL genotypes, and OR=6.8 for the combined NR2B/SK3 genotypes including high-risk alleles). These findings point to the contribution of genes associated with the NMDA-R signaling pathway to predisposition and development of AN. PMID:16157352

  2. Molecular determinants of NMDA receptor internalization.

    PubMed

    Roche, K W; Standley, S; McCallum, J; Dune Ly, C; Ehlers, M D; Wenthold, R J

    2001-08-01

    Although synaptic AMPA receptors have been shown to rapidly internalize, synaptic NMDA receptors are reported to be static. It is not certain whether NMDA receptor stability at synaptic sites is an inherent property of the receptor, or is due to stabilization by scaffolding proteins. In this study, we demonstrate that NMDA receptors are internalized in both heterologous cells and neurons, and we define an internalization motif, YEKL, on the distal C-terminus of NR2B. In addition, we show that the synaptic protein PSD-95 inhibits NR2B-mediated internalization, and that deletion of the PDZ-binding domain of NR2B increases internalization in neurons. This suggests an involvement for PSD-95 in NMDA receptor regulation and an explanation for NMDA receptor stability at synaptic sites. PMID:11477425

  3. Physiology and pathology of NMDA receptors.

    PubMed

    Petrović, M; Horák, M; Sedlácek, M; Vyklický, L

    2005-01-01

    Ionotropic glutamate receptors of the N-methyl-D-aspartate (NMDA) subtype are highly expressed in the central nervous system and are involved in excitatory synaptic transmission and synaptic plasticity. Prolonged activation of NMDA receptors can lead to excitotoxicity, which is implicated in the pathogenesis of neurodegeneration occurring in various acute and chronic disorders of the central nervous system. Recent advances in understanding the function, pharmacology, genetics and structure of NMDA receptors has promoted a search for new compounds that could be therapeutically used. These compounds act on agonist binding sites, either apart from them or directly within the ion channel pore. Members of the last group are called open channel blockers, and some of them, such as memantine and ketamine, are already clinically used. Kinetic modeling of NMDA receptor activity was employed to define the effects of various groups of modulators. Quantifying the action of these substances by kinetic parameters can help us to reveal the molecular mechanism of action at the receptor and to characterize the dependence of its action on the mode of NMDA receptor activation. Two modes are considered: phasic activation, induced by synaptically released glutamate, and tonic activation, which is expected to occur under pathological conditions when low, but sustained levels of glutamate activate NMDA receptors. The aim of our review is to summarize the recent data about the structural and functional properties of NMDA receptors and their role in long-term potentiation and excitotoxicity. PMID:16315761

  4. Differential Expression of AMPA Subunits Induced by NMDA Intrahippocampal Injection in Rats

    PubMed Central

    Fachim, Helene A.; Pereira, Adriana C.; Iyomasa-Pilon, Melina M.; Rosa, Maria L. N. M.

    2016-01-01

    Glutamate is involved in excitotoxic mechanisms by interacting with different receptors. Such interactions result in neuronal death associated with several neurodegenerative disorders of the central nervous system (CNS). The aim of this work was to study the time course of changes in the expression of GluR1 and GluR2 subunits of glutamate amino-acid-3-hydroxy-5-methyl-isoxazol-4-propionic acid (AMPA) receptors in rat hippocampus induced by NMDA intrahippocampal injection. Rats were submitted to stereotaxic surgery for NMDA or saline (control) microinjection into dorsal hippocampus and the parameters were evaluated 24 h, 1, 2, and 4 weeks after injection. The extension and efficacy of the NMDA-induced injury were evaluated by Morris water maze (MWM) behavioral test and Nissl staining. The expression of GluR1 and GluR2 receptors, glial fibrillary acidic protein (GFAP), and neuronal marker (NeuN) was analyzed by immunohistochemistry. It was observed the impairment of learning and memory functions, loss of neuronal cells, and glial proliferation in CA1 area of NMDA compared with control groups, confirming the injury efficacy. In addition, NMDA injection induced distinct changes in GluR1 and GluR2 expression over the time. In conclusion, such changes may be related to the complex mechanism triggered in response to NMDA injection resulting in a local injury and in the activation of neuronal plasticity. PMID:26912994

  5. Human neuroepithelial cells express NMDA receptors.

    PubMed

    Sharp, Christopher D; Fowler, M; Jackson, T H; Houghton, J; Warren, A; Nanda, A; Chandler, I; Cappell, B; Long, A; Minagar, A; Alexander, J S

    2003-11-13

    L-glutamate, an excitatory neurotransmitter, binds to both ionotropic and metabotropic glutamate receptors. In certain parts of the brain the BBB contains two normally impermeable barriers: 1) cerebral endothelial barrier and 2) cerebral epithelial barrier. Human cerebral endothelial cells express NMDA receptors; however, to date, human cerebral epithelial cells (neuroepithelial cells) have not been shown to express NMDA receptor message or protein. In this study, human hypothalamic sections were examined for NMDA receptors (NMDAR) expression via immunohistochemistry and murine neuroepithelial cell line (V1) were examined for NMDAR via RT-PCR and Western analysis. We found that human cerebral epithelium express protein and cultured mouse neuroepithelial cells express both mRNA and protein for the NMDA receptor. These findings may have important consequences for neuroepithelial responses during excitotoxicity and in disease. PMID:14614784

  6. Oxidative stress upregulates the NMDA receptor on cerebrovascular endothelium.

    PubMed

    Betzen, Christian; White, Robin; Zehendner, Christoph M; Pietrowski, Eweline; Bender, Bianca; Luhmann, Heiko J; Kuhlmann, Christoph R W

    2009-10-15

    N-methyl-d-aspartate receptor (NMDA-R)-mediated oxidative stress has been implicated in blood-brain barrier (BBB) disruption in a variety of neuropathological diseases. Although some interactions between both phenomena have been elucidated, possible influences of reactive oxygen species (ROS) on the NMDA-R itself have so far been neglected. The objective of this study was to examine how the cerebroendothelial NMDA-R is affected by exposure to oxidative stress and to assess possible influences on BBB integrity. RT-PCR confirmed several NMDA-R subunits (NR1, NR2B-D) expressed in the bEnd3 cell line (murine cerebrovascular endothelial cells). NR1 protein expression after exposure to ROS was observed via in-cell Western. The functionality of the expressed NMDA-R was determined by measuring DiBAC fluorescence in ROS-preexposed cells upon stimulation with the specific agonist NMDA. Finally, the effects on barrier integrity were evaluated using the ECIS system to detect changes in monolayer impedance upon NMDA-R stimulation after exposure to ROS. The expression of NR1 significantly (p<0.001) increased 72 h after 30 min exposure to superoxide (+33.8+/-7.5%), peroxynitrite (+84.9+/-10.7%), or hydrogen peroxide (+92.8+/-7.6%), resulting in increased cellular response to NMDA-R stimulation and diminished monolayer impedance. We conclude that oxidative stress upregulates NMDA-R on cerebrovascular endothelium and thus heightens susceptibility to glutamate-induced BBB disruption. PMID:19660541

  7. Acute hypoxia differentially affects the NMDA receptor NR1, NR2A and NR2B subunit mRNA levels in the developing chick optic tectum: stage-dependent plasticity in the 2B-2A ratio.

    PubMed

    Vacotto, Marina; Rapacioli, Melina; Flores, Vladimir; de Plazas, Sara Fiszer

    2010-10-01

    It is known that the NMDA-R NR1 subunit is needed for the receptor activity and that under hypoxia the evolution toward apoptosis or neuronal survival depends on the balance NR2A/NR2B subunits. This paper analyzes the effect of acute hypoxia on the above mentioned subunits mRNAs during development. The mean percentage of NR1+ neurons displayed the higher plasticity during development while the NR2A+ neurons the higher stability. Acute hypoxia increased the mean percentage of NR1+ and NR2B+ neurons at ED12 but only that of NR1+ neurons at ED18. Acute hypoxia increased the levels of expression of NR1 and NR2B mRNAs at ED12 without changes in the NR2A mRNA. During early stages there is a higher sensitivity to change the subunits mRNA levels under a hypoxic treatment. At ED12 acute hypoxia increased the probability of co-expression of the NR1-NR2A and NR1-NR2B subunits combinations, the level of NR1 and NR2B and the ratio NR2B/NR2A. These conditions facilitate the evolution towards apoptosis. PMID:20596770

  8. NMDA receptors in hyperammonemia and hepatic encephalopathy.

    PubMed

    Llansola, Marta; Rodrigo, Regina; Monfort, Pilar; Montoliu, Carmina; Kosenko, Elena; Cauli, Omar; Piedrafita, Blanca; El Mlili, Nisrin; Felipo, Vicente

    2007-12-01

    The NMDA type of glutamate receptors modulates learning and memory. Excessive activation of NMDA receptors leads to neuronal degeneration and death. Hyperammonemia and liver failure alter the function of NMDA receptors and of some associated signal transduction pathways. The alterations are different in acute and chronic hyperammonemia and liver failure. Acute intoxication with large doses of ammonia (and probably acute liver failure) leads to excessive NMDA receptors activation, which is responsible for ammonia-induced death. In contrast, chronic hyperammonemia induces adaptive responses resulting in impairment of signal transduction associated to NMDA receptors. The function of the glutamate-nitric oxide-cGMP pathway is impaired in brain in vivo in animal models of chronic liver failure or hyperammonemia and in homogenates from brains of patients died in hepatic encephalopathy. The impairment of this pathway leads to reduced cGMP and contributes to impaired cognitive function in hepatic encephalopathy. Learning ability is reduced in animal models of chronic liver failure and hyperammonemia and is restored by pharmacological manipulation of brain cGMP by administering phosphodiesterase inhibitors (zaprinast or sildenafil) or cGMP itself. NMDA receptors are therefore involved both in death induced by acute ammonia toxicity (and likely by acute liver failure) and in cognitive impairment in hepatic encephalopathy. PMID:17701332

  9. Developmental expression of N-methyl-D-aspartate (NMDA) receptor subunits in human white and gray matter: potential mechanism of increased vulnerability in the immature brain.

    PubMed

    Jantzie, Lauren L; Talos, Delia M; Jackson, Michele C; Park, Hyun-Kyung; Graham, Dionne A; Lechpammer, Mirna; Folkerth, Rebecca D; Volpe, Joseph J; Jensen, Frances E

    2015-02-01

    The pathophysiology of perinatal brain injury is multifactorial and involves hypoxia-ischemia (HI) and inflammation. N-methyl-d-aspartate receptors (NMDAR) are present on neurons and glia in immature rodents, and NMDAR antagonists are protective in HI models. To enhance clinical translation of rodent data, we examined protein expression of 6 NMDAR subunits in postmortem human brains without injury from 20 postconceptional weeks through adulthood and in cases of periventricular leukomalacia (PVL). We hypothesized that the developing brain is intrinsically vulnerable to excitotoxicity via maturation-specific NMDAR levels and subunit composition. In normal white matter, NR1 and NR2B levels were highest in the preterm period compared with adult. In gray matter, NR2A and NR3A expression were highest near term. NR2A was significantly elevated in PVL white matter, with reduced NR1 and NR3A in gray matter compared with uninjured controls. These data suggest increased NMDAR-mediated vulnerability during early brain development due to an overall upregulation of individual receptors subunits, in particular, the presence of highly calcium permeable NR2B-containing and magnesium-insensitive NR3A NMDARs. These data improve understanding of molecular diversity and heterogeneity of NMDAR subunit expression in human brain development and supports an intrinsic prenatal vulnerability to glutamate-mediated injury; validating NMDAR subunit-specific targeted therapies for PVL. PMID:24046081

  10. Developmental Expression of N-Methyl-d-Aspartate (NMDA) Receptor Subunits in Human White and Gray Matter: Potential Mechanism of Increased Vulnerability in the Immature Brain

    PubMed Central

    Jantzie, Lauren L.; Talos, Delia M.; Jackson, Michele C.; Park, Hyun-Kyung; Graham, Dionne A.; Lechpammer, Mirna; Folkerth, Rebecca D.; Volpe, Joseph J.; Jensen, Frances E.

    2015-01-01

    The pathophysiology of perinatal brain injury is multifactorial and involves hypoxia-ischemia (HI) and inflammation. N-methyl-d-aspartate receptors (NMDAR) are present on neurons and glia in immature rodents, and NMDAR antagonists are protective in HI models. To enhance clinical translation of rodent data, we examined protein expression of 6 NMDAR subunits in postmortem human brains without injury from 20 postconceptional weeks through adulthood and in cases of periventricular leukomalacia (PVL). We hypothesized that the developing brain is intrinsically vulnerable to excitotoxicity via maturation-specific NMDAR levels and subunit composition. In normal white matter, NR1 and NR2B levels were highest in the preterm period compared with adult. In gray matter, NR2A and NR3A expression were highest near term. NR2A was significantly elevated in PVL white matter, with reduced NR1 and NR3A in gray matter compared with uninjured controls. These data suggest increased NMDAR-mediated vulnerability during early brain development due to an overall upregulation of individual receptors subunits, in particular, the presence of highly calcium permeable NR2B-containing and magnesium-insensitive NR3A NMDARs. These data improve understanding of molecular diversity and heterogeneity of NMDAR subunit expression in human brain development and supports an intrinsic prenatal vulnerability to glutamate-mediated injury; validating NMDAR subunit-specific targeted therapies for PVL. PMID:24046081

  11. Subunit-selective N-Methyl-d-aspartate (NMDA) Receptor Signaling through Brefeldin A-resistant Arf Guanine Nucleotide Exchange Factors BRAG1 and BRAG2 during Synapse Maturation.

    PubMed

    Elagabani, Mohammad Nael; Briševac, Dušica; Kintscher, Michael; Pohle, Jörg; Köhr, Georg; Schmitz, Dietmar; Kornau, Hans-Christian

    2016-04-22

    The maturation of glutamatergic synapses in the CNS is regulated by NMDA receptors (NMDARs) that gradually change from a GluN2B- to a GluN2A-dominated subunit composition during postnatal development. Here we show that NMDARs control the activity of the small GTPase ADP-ribosylation factor 6 (Arf6) by consecutively recruiting two related brefeldin A-resistant Arf guanine nucleotide exchange factors, BRAG1 and BRAG2, in a GluN2 subunit-dependent manner. In young cortical cultures, GluN2B and BRAG1 tonically activated Arf6. In mature cultures, Arf6 was activated through GluN2A and BRAG2 upon NMDA treatment, whereas the tonic Arf6 activation was not detectable any longer. This shift in Arf6 regulation and the associated drop in Arf6 activity were reversed by a knockdown of BRAG2. Given their sequential recruitment during development, we examined whether BRAG1 and BRAG2 influence synaptic currents in hippocampal CA1 pyramidal neurons using patch clamp recordings in acute slices from mice at different ages. The number of AMPA receptor (AMPAR) miniature events was reduced by depletion of BRAG1 but not by depletion of BRAG2 during the first 2 weeks after birth. In contrast, depletion of BRAG2 during postnatal weeks 4 and 5 reduced the number of AMPAR miniature events and compromised the quantal sizes of both AMPAR and NMDAR currents evoked at Schaffer collateral synapses. We conclude that both Arf6 activation through GluN2B-BRAG1 during early development and the transition from BRAG1- to BRAG2-dependent Arf6 signaling induced by the GluN2 subunit switch are critical for the development of mature glutamatergic synapses. PMID:26884337

  12. Neuroprotection by NMDA receptor antagonists in a variety of neuropathologies.

    PubMed

    Palmer, G C

    2001-09-01

    Because of adverse reactions, early efforts to introduce high affinity competitive or use-dependent NMDA receptor antagonists into patients suffering from stroke, head trauma or epilepsy met with failure. Later it was discovered that both low affinity use-dependent NMDA receptor antagonists and compounds with selective affinity for the NR2B receptor subunit met the criteria for safe administration into patients. Furthermore, these low affinity antagonists exhibit significant mechanistic differences from their higher affinity counterparts. Success of the latter is attested to the ability of the following low affinity compounds to be marketed: 1) Cough suppressant-dextromethorphan (available for decades); 2) Parkinson's disease--amantadine, memantine and budipine; 3) Dementia--memantine; and 4) Epilepsy--felbamate. Moreover, Phase III clinical trials are ongoing with remacemide for epilepsy and Huntington's disease and head trauma for HU-211. A host of compounds are or were under evaluation for the possible treatment of stroke, head trauma, hyperalgesia and various neurodegenerative disorders. Despite the fact that other drugs with associated NMDA receptor mechanisms have reached clinical status, this review focuses only on those competitive and use-dependent NMDA receptor antagonists that reached clinical trails. The ensuing discussions link the in vivo pharmacological investigations that led to the success/mistakes/ failures for eventual testing of promising compounds in the clinic. PMID:11554551

  13. Testing NMDA receptor block as a therapeutic strategy for reducing ischaemic damage to CNS white matter.

    PubMed

    Bakiri, Yamina; Hamilton, Nicola B; Káradóttir, Ragnhildur; Attwell, David

    2008-01-15

    Damage to oligodendrocytes caused by glutamate release contributes to mental or physical handicap in periventricular leukomalacia, spinal cord injury, multiple sclerosis, and stroke, and has been attributed to activation of AMPA/kainate receptors. However, glutamate also activates unusual NMDA receptors in oligodendrocytes, which can generate an ion influx even at the resting potential in a physiological [Mg2+]. Here, we show that the clinically licensed NMDA receptor antagonist memantine blocks oligodendrocyte NMDA receptors at concentrations achieved therapeutically. Simulated ischaemia released glutamate which activated NMDA receptors, as well as AMPA/kainate receptors, on mature and precursor oligodendrocytes. Although blocking AMPA/kainate receptors alone during ischaemia had no effect, combining memantine with an AMPA/kainate receptor blocker, or applying the NMDA blocker MK-801 alone, improved recovery of the action potential in myelinated axons after the ischaemia. These data suggest NMDA receptor blockers as a potentially useful treatment for some white matter diseases and define conditions under which these blockers may be useful therapeutically. Our results highlight the importance of developing new antagonists selective for oligodendrocyte NMDA receptors based on their difference in subunit structure from most neuronal NMDA receptors. PMID:18046734

  14. Functional Interaction Between Na/K-ATPase and NMDA Receptor in Cerebellar Neurons.

    PubMed

    Akkuratov, Evgeny E; Lopacheva, Olga M; Kruusmägi, Markus; Lopachev, Alexandr V; Shah, Zahoor A; Boldyrev, Alexander A; Liu, Lijun

    2015-12-01

    NMDA receptors play a crucial role in regulating synaptic plasticity and memory. Activation of NMDA receptors changes intracellular concentrations of Na(+) and K(+), which are subsequently restored by Na/K-ATPase. We used immunochemical and biochemical methods to elucidate the potential mechanisms of interaction between these two proteins. We observed that NMDA receptor and Na/K-ATPase interact with each other and this interaction was shown for both isoforms of α subunit (α1 and α3) of Na/K-ATPase expressed in neurons. Using Western blotting, we showed that long-term exposure of the primary culture of cerebellar neurons to nanomolar concentrations of ouabain (a cardiotonic steroid, a specific ligand of Na/K-ATPase) leads to a decrease in the levels of NMDA receptors which is likely mediated by the α3 subunit of Na/K-ATPase. We also observed a decrease in enzymatic activity of the α1 subunit of Na/K-ATPase caused by NMDA receptor activation. This effect is mediated by an increase in intracellular Ca(2+). Thus, Na/K-ATPase and NMDA receptor can interact functionally by forming a macromolecular complex which can be important for restoring ionic balance after neuronal excitation. Furthermore, this interaction suggests that NMDA receptor function can be regulated by endogenous cardiotonic steroids which recently have been found in cerebrospinal fluid or by pharmacological drugs affecting Na/K-ATPase function. PMID:25381029

  15. Crystal structure of a heterotetrameric NMDA receptor ion channel

    PubMed Central

    Karakas, Erkan; Furukawa, Hiro

    2014-01-01

    N -methyl-D-aspartate (NMDA) receptors belong to the family of ionotropic glutamate receptors, which mediate most excitatory synaptic transmission in mammalian brains. Calcium permeation triggered by activation of NMDA receptors is the pivotal event for initiation of neuronal plasticity. Here we show the crystal structure of the intact heterotetrameric GluN1/GluN2B NMDA receptor ion channel at 4 Å. The NMDA receptors are arranged as a dimer of GluN1-GluN2B heterodimers with the two-fold symmetry axis running through the entire molecule composed of an amino terminal domain (ATD), a ligand-binding domain (LBD), and a transmembrane domain (TMD). The ATD and LBD are much more highly packed in the NMDA receptors than non-NMDA receptors, which may explain why ATD regulates ion channel activity in NMDA receptors but not in non-NMDA receptors. PMID:24876489

  16. GABA-A and NMDA receptor subunit mRNA expression is altered in the caudate but not the putamen of the postmortem brains of alcoholics

    PubMed Central

    Bhandage, Amol K.; Jin, Zhe; Bazov, Igor; Kononenko, Olga; Bakalkin, Georgy; Korpi, Esa R.; Birnir, Bryndis

    2014-01-01

    Chronic consumption of alcohol by humans has been shown to lead to impairment of executive and cognitive functions. Here, we have studied the mRNA expression of ion channel receptors for glutamate and GABA in the dorsal striatum of post-mortem brains from alcoholics (n = 29) and normal controls (n = 29), with the focus on the caudate nucleus that is associated with the frontal cortex executive functions and automatic thinking and on the putamen area that is linked to motor cortices and automatic movements. The results obtained by qPCR assay revealed significant changes in the expression of specific excitatory ionotropic glutamate and inhibitory GABA-A receptor subunit genes in the caudate but not the putamen. Thus, in the caudate we found reduced levels of mRNAs encoding the GluN2A glutamate receptor and the δ, ε, and ρ2 GABA-A receptor subunits, and increased levels of the mRNAs encoding GluD1, GluD2, and GABA-A γ1 subunits in the alcoholics as compared to controls. Interestingly in the controls, 11 glutamate and 5 GABA-A receptor genes were more prominently expressed in the caudate than the putamen (fold-increase varied from 1.24 to 2.91). Differences in gene expression patterns between the striatal regions may underlie differences in associated behavioral outputs. Our results suggest an altered balance between caudate-mediated voluntarily controlled and automatic behaviors in alcoholics, including diminished executive control on goal-directed alcohol-seeking behavior. PMID:25538565

  17. NMDA Receptor Activity in Neuropsychiatric Disorders

    PubMed Central

    Lakhan, Shaheen E.; Caro, Mario; Hadzimichalis, Norell

    2013-01-01

    N-Methyl-d-aspartate (NMDA) receptors play a variety of physiologic roles and their proper signaling is essential for cellular homeostasis. Any disruption in this pathway, leading to either enhanced or decreased activity, may result in the manifestation of neuropsychiatric pathologies such as schizophrenia, mood disorders, substance induced psychosis, Huntington’s disease, Alzheimer’s disease, and neuropsychiatric systemic lupus erythematosus. Here, we explore the notion that the overlap in activity of at least one biochemical pathway, the NMDA receptor pathway, may be the link to understanding the overlap in psychotic symptoms between diseases. This review intends to present a broad overview of those neuropsychiatric disorders for which alternations in NMDA receptor activity is prominent thus suggesting that continued direction of pharmaceutical intervention to this pathway may present a viable option for managing symptoms. PMID:23772215

  18. Multiple domains in the C-terminus of NMDA receptor GluN2B subunit contribute to neuronal death following in vitro ischemia.

    PubMed

    Vieira, Marta M; Schmidt, Jeannette; Ferreira, Joana S; She, Kevin; Oku, Shinichiro; Mele, Miranda; Santos, Armanda E; Duarte, Carlos B; Craig, Ann Marie; Carvalho, Ana Luísa

    2016-05-01

    Global cerebral ischemia induces selective degeneration of specific subsets of neurons throughout the brain, particularly in the hippocampus and cortex. One of the major hallmarks of cerebral ischemia is excitotoxicity, characterized by overactivation of glutamate receptors leading to intracellular Ca(2+) overload and ultimately neuronal demise. N-methyl-d-aspartate receptors (NMDARs) are considered to be largely responsible for excitotoxic injury due to their high Ca(2+) permeability. In the hippocampus and cortex, these receptors are most prominently composed of combinations of two GluN1 subunits and two GluN2A and/or GluN2B subunits. Due to the controversy regarding the differential role of GluN2A and GluN2B subunits in excitotoxic cell death, we investigated the role of GluN2B in the activation of pro-death signaling following an in vitro model of global ischemia, oxygen and glucose deprivation (OGD). For this purpose, we used GluN2B(-/-) mouse cortical cultures and observed that OGD-induced damage was reduced in these neurons, and partially prevented in wild-type rat neurons by a selective GluN2B antagonist. Notably, we found a crucial role of the C-terminal domain of the GluN2B subunit in triggering excitotoxic signaling. Indeed, expression of YFP-GluN2B C-terminus mutants for the binding sites to post-synaptic density protein 95 (PSD95), Ca(2+)-calmodulin kinase IIα (CaMKIIα) or clathrin adaptor protein 2 (AP2) failed to mediate neuronal death in OGD conditions. We focused on the GluN2B-CaMKIIα interaction and found a determinant role of this interaction in OGD-induced death. Inhibition or knock-down of CaMKIIα exerted a neuroprotective effect against OGD-induced death, whereas overexpression of this kinase had a detrimental effect. Importantly, in comparison with neurons overexpressing wild-type CaMKIIα, neurons overexpressing a mutant form of the kinase (CaMKII-I205K), unable to interact with GluN2B, were partially protected against OGD-induced damage

  19. NMDA receptors mediate calcium accumulation in myelin during chemical ischaemia.

    PubMed

    Micu, I; Jiang, Q; Coderre, E; Ridsdale, A; Zhang, L; Woulfe, J; Yin, X; Trapp, B D; McRory, J E; Rehak, R; Zamponi, G W; Wang, W; Stys, P K

    2006-02-23

    Central nervous system myelin is a specialized structure produced by oligodendrocytes that ensheaths axons, allowing rapid and efficient saltatory conduction of action potentials. Many disorders promote damage to and eventual loss of the myelin sheath, which often results in significant neurological morbidity. However, little is known about the fundamental mechanisms that initiate myelin damage, with the assumption being that its fate follows that of the parent oligodendrocyte. Here we show that NMDA (N-methyl-d-aspartate) glutamate receptors mediate Ca2+ accumulation in central myelin in response to chemical ischaemia in vitro. Using two-photon microscopy, we imaged fluorescence of the Ca2+ indicator X-rhod-1 loaded into oligodendrocytes and the cytoplasmic compartment of the myelin sheath in adult rat optic nerves. The AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid)/kainate receptor antagonist NBQX completely blocked the ischaemic Ca2+ increase in oligodendroglial cell bodies, but only modestly reduced the Ca2+ increase in myelin. In contrast, the Ca2+ increase in myelin was abolished by broad-spectrum NMDA receptor antagonists (MK-801, 7-chlorokynurenic acid, d-AP5), but not by more selective blockers of NR2A and NR2B subunit-containing receptors (NVP-AAM077 and ifenprodil). In vitro ischaemia causes ultrastructural damage to both axon cylinders and myelin. NMDA receptor antagonism greatly reduced the damage to myelin. NR1, NR2 and NR3 subunits were detected in myelin by immunohistochemistry and immunoprecipitation, indicating that all necessary subunits are present for the formation of functional NMDA receptors. Our data show that the mature myelin sheath can respond independently to injurious stimuli. Given that axons are known to release glutamate, our finding that the Ca2+ increase was mediated in large part by activation of myelinic NMDA receptors suggests a new mechanism of axo-myelinic signalling. Such a mechanism may represent a

  20. Activation of NMDA receptors and the mechanism of inhibition by ifenprodil.

    PubMed

    Tajima, Nami; Karakas, Erkan; Grant, Timothy; Simorowski, Noriko; Diaz-Avalos, Ruben; Grigorieff, Nikolaus; Furukawa, Hiro

    2016-06-01

    The physiology of N-methyl-d-aspartate (NMDA) receptors is fundamental to brain development and function. NMDA receptors are ionotropic glutamate receptors that function as heterotetramers composed mainly of GluN1 and GluN2 subunits. Activation of NMDA receptors requires binding of neurotransmitter agonists to a ligand-binding domain (LBD) and structural rearrangement of an amino-terminal domain (ATD). Recent crystal structures of GluN1-GluN2B NMDA receptors bound to agonists and an allosteric inhibitor, ifenprodil, represent the allosterically inhibited state. However, how the ATD and LBD move to activate the NMDA receptor ion channel remains unclear. Here we applied X-ray crystallography, single-particle electron cryomicroscopy and electrophysiology to rat NMDA receptors to show that, in the absence of ifenprodil, the bi-lobed structure of GluN2 ATD adopts an open conformation accompanied by rearrangement of the GluN1-GluN2 ATD heterodimeric interface, altering subunit orientation in the ATD and LBD and forming an active receptor conformation that gates the ion channel. PMID:27135925

  1. BDNF released during neuropathic pain potentiates NMDA receptors in primary afferent terminals.

    PubMed

    Chen, Wenling; Walwyn, Wendy; Ennes, Helena S; Kim, Hyeyoung; McRoberts, James A; Marvizón, Juan Carlos G

    2014-05-01

    NMDA receptors in primary afferent terminals can contribute to hyperalgesia by increasing neurotransmitter release. In rats and mice, we found that the ability of intrathecal NMDA to induce neurokinin 1 receptor (NK1R) internalization (a measure of substance P release) required a previous injection of BDNF. Selective knock-down of NMDA receptors in primary afferents decreased NMDA-induced NK1R internalization, confirming the presynaptic location of these receptors. The effect of BDNF was mediated by tropomyosin-related kinase B (trkB) receptors and not p75 neurotrophin receptors (p75(NTR) ), because it was not produced by proBDNF and was inhibited by the trkB antagonist ANA-12 but not by the p75(NTR) inhibitor TAT-Pep5. These effects are probably mediated through the truncated form of the trkB receptor as there is little expression of full-length trkB in dorsal root ganglion (DRG) neurons. Src family kinase inhibitors blocked the effect of BDNF, suggesting that trkB receptors promote the activation of these NMDA receptors by Src family kinase phosphorylation. Western blots of cultured DRG neurons revealed that BDNF increased Tyr(1472) phosphorylation of the NR2B subunit of the NMDA receptor, known to have a potentiating effect. Patch-clamp recordings showed that BDNF, but not proBDNF, increased NMDA receptor currents in cultured DRG neurons. NMDA-induced NK1R internalization was also enabled in a neuropathic pain model or by activating dorsal horn microglia with lipopolysaccharide. These effects were decreased by a BDNF scavenger, a trkB receptor antagonist and a Src family kinase inhibitor, indicating that BDNF released by microglia potentiates NMDA receptors in primary afferents during neuropathic pain. PMID:24611998

  2. NMDA Receptors: Power Switches for Oligodendrocytes.

    PubMed

    Krasnow, Anna M; Attwell, David

    2016-07-01

    The role of NMDA receptors in oligodendrocytes has been controversial. A new paper (Saab et al., 2016) suggests they play a key role in regulating glucose uptake in response to axonal glutamate release, thus controlling metabolic cooperation between oligodendrocytes and axons. PMID:27387644

  3. Phosphorylation of NMDA NR1 subunits in the myenteric plexus during TNBS induced colitis.

    PubMed

    Zhou, QiQi; Caudle, Robert M; Moshiree, Baharak; Price, Donald D; Verne, G Nicholas

    2006-10-01

    N-Methyl-d-aspartic acid (NMDA) receptors are known to function in the mediation of pain and have a significant role in the development of hyperalgesia following inflammation. Serine phosphorylation regulation of NMDA receptor function occurs in a variety of conditions. No studies have demonstrated a change in phosphorylation of enteric NMDA receptors following colonic inflammation. We examined the levels of NMDA NR1 phosphorylation in trinitrobenzene sulfonic acid (TNBS) induced colitis in rats and compared it to protein translation and the development of visceral hypersensitivity. We have previously, demonstrated an increase in the C1 cassette of NR1 mRNA expression at 14, 21, and 28 days following TNBS administration. In this study, we examined the NR1 serine phosphorylation at 14 days following TNBS injection. Male Sprague-Dawley rats (200-250 g) were treated with TNBS (20mg per rat) diluted in 50% ethanol (n=3) and vehicle controls of 50% ethanol (n=3). TNBS and vehicle controls were administered with a 24 gauge catheter inserted into the lumen of the rat colon. The animals were sacrificed at 14 days after induction of the colitis and their distal colon was retrieved for two-dimensional (2D) western blot analysis. Serine phosphorylation of the NR1 subunit with C1 cassette appears at 14 days after TNBS injection. In contrast, there was no NR1-C1 expression in the vehicle controls and untreated normal controls. These results suggest a role for colonic-NMDA receptor phosphorylation in the development of neuronal plasticity following colonic inflammation. Phosphorylation of NR1 may partially explain visceral hypersensitivity present during colonic inflammation. PMID:16942839

  4. A neuroprotective role of the NMDA receptor subunit GluN3A (NR3A) in ischemic stroke of the adult mouse

    PubMed Central

    Wei, Zheng Z.; Chen, Dongdong; Gu, Xiaohuan; Wei, Ling

    2015-01-01

    GluN3A or NR3A is a developmentally regulated N-methyl-d-aspartate receptor (NMDAR) subunit, showing a unique inhibitory role that decreases NMDAR current and the receptor-mediated Ca2+ influx. In the neonatal brain, GluN3A is shown to associate with synaptic maturation and spine formation and plays a neuroprotective role. Its functional role in the adult brain, however, is largely unknown. We tested the hypothesis that, disrespecting the relatively lower expression level of GluN3A in the adult brain, this inhibitory NMDAR subunit shows a protective action against ischemia-induced brain injury. In littermate wild-type (WT) and GluN3A knockout (KO) mice, focal cerebral ischemia was induced by permanent occlusion of right distal branches of the middle cerebral artery (MCA) plus 10-min ligation of both common carotid arteries (CCAs). Twenty-four hours after focal cerebral ischemia, the infarction volume assessed using 2,3,5-triphenyltetrazolium chloride (TTC) staining was significantly larger in GluN3A KO mice compared with WT mice. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining demonstrated enhanced cell death in GluN3A KO mice. Moreover, the deletion of GluN3A hindered sensorimotor functional recovery after stroke. It is suggested that, although the expression level is relatively lower in the adult brain, GluN3A is still a noteworthy regulator in ischemia-induced excitotoxicity and brain injury. PMID:25652449

  5. PSD-95 regulates NMDA receptors in developing cerebellar granule neurons of the rat

    PubMed Central

    Losi, Gabriele; Prybylowski, Kate; Fu, Zhanyan; Luo, Jianhong; Wenthold, Robert J; Vicini, Stefano

    2003-01-01

    We transfected a green fluorescent protein-tagged PSD-95 (PSD-95gfp) into cultured rat cerebellar granule cells (CGCs) to investigate the role of PSD-95 in excitatory synapse maturation. Cells were grown in low potassium to favour functional synapse formation in vitro. Transfected cells displayed clear clusters of PSD-95gfp, often at the extremities of the short dendritic trees. We recorded NMDA and AMPA miniature excitatory postsynaptic currents (NMDA- and AMPA-mESPCs) in the presence of TTX and bicuculline. At days in vitro (DIV) 7–8 PSD-95gfp-transfected cells had NMDA-mEPSCs with faster decay and smaller amplitudes than matching controls. In contrast, AMPA-mEPSC frequencies and amplitudes were increased. Whole-cell current density and ifenprodil sensitivity were reduced in PSD-95gfp cells, indicating a reduction of NR2B subunits containing NMDA receptors. No changes were observed compared to control when cells were transfected with cDNA for PSD-95gfp with palmitoylation site mutations that prevent targeting to the synapse. Overexpression of the NMDA receptor NR2A subunit, but not the NR2B subunit, prevented NMDA-mEPSC amplitude reduction when cotransfected with PSD-95gfp. PSD-95gfp overexpression produced faster NMDA-mEPSC decay when transfected alone or with either NR2 subunit. Surface staining of the epitope-tagged NR2 subunits revealed that colocalization with PSD-95gfp was higher for flag-tagged NR2A subunit clusters than for flag-tagged NR2B subunit clusters. These data suggest that PSD-95 overexpression in CGCs favours synaptic maturation by allowing synaptic insertion of NR2A and depressing expression of NR2B subunits. PMID:12576494

  6. Dicholine succinate, the neuronal insulin sensitizer, normalizes behavior, REM sleep, hippocampal pGSK3 beta and mRNAs of NMDA receptor subunits in mouse models of depression

    PubMed Central

    Cline, Brandon H.; Costa-Nunes, Joao P.; Cespuglio, Raymond; Markova, Natalyia; Santos, Ana I.; Bukhman, Yury V.; Kubatiev, Aslan; Steinbusch, Harry W. M.; Lesch, Klaus-Peter; Strekalova, Tatyana

    2015-01-01

    Central insulin receptor-mediated signaling is attracting the growing attention of researchers because of rapidly accumulating evidence implicating it in the mechanisms of plasticity, stress response, and neuropsychiatric disorders including depression. Dicholine succinate (DS), a mitochondrial complex II substrate, was shown to enhance insulin-receptor mediated signaling in neurons and is regarded as a sensitizer of the neuronal insulin receptor. Compounds enhancing neuronal insulin receptor-mediated transmission exert an antidepressant-like effect in several pre-clinical paradigms of depression; similarly, such properties for DS were found with a stress-induced anhedonia model. Here, we additionally studied the effects of DS on several variables which were ameliorated by other insulin receptor sensitizers in mice. Pre-treatment with DS of chronically stressed C57BL6 mice rescued normal contextual fear conditioning, hippocampal gene expression of NMDA receptor subunit NR2A, the NR2A/NR2B ratio and increased REM sleep rebound after acute predation. In 18-month-old C57BL6 mice, a model of elderly depression, DS restored normal sucrose preference and activated the expression of neural plasticity factors in the hippocampus as shown by Illumina microarray. Finally, young naïve DS-treated C57BL6 mice had reduced depressive- and anxiety-like behaviors and, similarly to imipramine-treated mice, preserved hippocampal levels of the phosphorylated (inactive) form of GSK3 beta that was lowered by forced swimming in pharmacologically naïve animals. Thus, DS can ameliorate behavioral and molecular outcomes under a variety of stress- and depression-related conditions. This further highlights neuronal insulin signaling as a new factor of pathogenesis and a potential pharmacotherapy of affective pathologies. PMID:25767439

  7. Dicholine succinate, the neuronal insulin sensitizer, normalizes behavior, REM sleep, hippocampal pGSK3 beta and mRNAs of NMDA receptor subunits in mouse models of depression.

    PubMed

    Cline, Brandon H; Costa-Nunes, Joao P; Cespuglio, Raymond; Markova, Natalyia; Santos, Ana I; Bukhman, Yury V; Kubatiev, Aslan; Steinbusch, Harry W M; Lesch, Klaus-Peter; Strekalova, Tatyana

    2015-01-01

    Central insulin receptor-mediated signaling is attracting the growing attention of researchers because of rapidly accumulating evidence implicating it in the mechanisms of plasticity, stress response, and neuropsychiatric disorders including depression. Dicholine succinate (DS), a mitochondrial complex II substrate, was shown to enhance insulin-receptor mediated signaling in neurons and is regarded as a sensitizer of the neuronal insulin receptor. Compounds enhancing neuronal insulin receptor-mediated transmission exert an antidepressant-like effect in several pre-clinical paradigms of depression; similarly, such properties for DS were found with a stress-induced anhedonia model. Here, we additionally studied the effects of DS on several variables which were ameliorated by other insulin receptor sensitizers in mice. Pre-treatment with DS of chronically stressed C57BL6 mice rescued normal contextual fear conditioning, hippocampal gene expression of NMDA receptor subunit NR2A, the NR2A/NR2B ratio and increased REM sleep rebound after acute predation. In 18-month-old C57BL6 mice, a model of elderly depression, DS restored normal sucrose preference and activated the expression of neural plasticity factors in the hippocampus as shown by Illumina microarray. Finally, young naïve DS-treated C57BL6 mice had reduced depressive- and anxiety-like behaviors and, similarly to imipramine-treated mice, preserved hippocampal levels of the phosphorylated (inactive) form of GSK3 beta that was lowered by forced swimming in pharmacologically naïve animals. Thus, DS can ameliorate behavioral and molecular outcomes under a variety of stress- and depression-related conditions. This further highlights neuronal insulin signaling as a new factor of pathogenesis and a potential pharmacotherapy of affective pathologies. PMID:25767439

  8. Alcohol and NMDA receptor: current research and future direction

    PubMed Central

    Chandrasekar, Raman

    2013-01-01

    The brain is one of the major targets of alcohol actions. Most of the excitatory synaptic transmission in the central nervous system is mediated by N-methyl-D-aspartate (NMDA) receptors. However, one of the most devastating effects of alcohol leads to brain shrinkage, loss of nerve cells at specific regions through a mechanism involving excitotoxicity, oxidative stress. Earlier studies have indicated that chronic exposure to ethanol both in vivo and in vitro, increases NR1 and NR2B gene expression and their polypeptide levels. The effect of alcohol and molecular changes on the regulatory process, which modulates NMDAR functions including factors altering transcription, translation, post-translational modifications, and protein expression, as well as those influencing their interactions with different regulatory proteins (downstream effectors) are incessantly increasing at the cellular level. Further, I discuss the various genetically altered mice approaches that have been used to study NMDA receptor subunits and their functional implication. In a recent countable review, epigenetic dimension (i.e., histone modification-induced chromatin remodeling and DNA methylation, in the process of alcohol related neuroadaptation) is one of the key molecular mechanisms in alcohol mediated NMDAR alteration. Here, I provide a recount on what has already been achieved, current trends and how the future research/studies of the NMDA receptor might lead to even greater engagement with many possible new insights into the neurobiology and treatment of alcoholism. PMID:23754976

  9. Enhancement of GluN2B Subunit-Containing NMDA Receptor Underlies Serotonergic Regulation of Long-Term Potentiation after Critical Period in the Rat Visual Cortex

    PubMed Central

    Joo, Kayoung; Rhie, Duck-Joo

    2015-01-01

    Serotonin [5-hydroxytryptamine (5-HT)] regulates synaptic plasticity in the visual cortex. Although the effects of 5-HT on plasticity showed huge diversity depending on the ages of animals and species, it has been unclear how 5-HT can show such diverse effects. In the rat visual cortex, 5-HT suppressed long-term potentiation (LTP) at 5 weeks but enhanced LTP at 8 weeks. We speculated that this difference may originate from differential regulation of neurotransmission by 5-HT between the age groups. Thus, we investigated the effects of 5-HT on apha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR)-, γ-aminobutyric acid receptor type A (GABAAR)-, and N-methyl-D-aspartic acid receptor (NMDAR)-mediated neurotransmissions and their involvement in the differential regulation of plasticity between 5 and 8 weeks. AMPAR-mediated currents were not affected by 5-HT at both 5 and 8 weeks. GABAAR-mediated currents were enhanced by 5-HT at both age groups. However, 5-HT enhanced NMDAR-mediated currents only at 8 weeks. The enhancement of NMDAR-mediated currents appeared to be mediated by the enhanced function of GluN2B subunit-containing NMDAR. The enhanced GABAAR- and NMDAR-mediated neurotransmissions were responsible for the suppression of LTP at 5 weeks and the facilitation of LTP at 8 weeks, respectively. These results indicate that the effects of 5-HT on neurotransmission change with development, and the changes may underlie the differential regulation of synaptic plasticity between different age groups. Thus, the developmental changes in 5-HT function should be carefully considered while investigating the 5-HT-mediated metaplastic control of the cortical network. PMID:26557019

  10. Modulation of the NMDA receptor by polyamines

    SciTech Connect

    Williams, K.; Romano, C.; Dichter, M.A.; Molinoff, P.B. )

    1991-01-01

    Results of recent biochemical and electrophysiological studies have suggested that a recognition site for polyamines exists as part of the NMDA receptor complex. The endogenous polyamines spermine and spermidine increase the binding of open-channel blockers and increase NMDA-elicited currents in cultured neutrons. These polyamines have been termed agonists at the polyamine recognition site. Studies of the effects of natural and synthetic polyamines on the binding of ({sup 3}H)MK-801 and on NMDA-elicited currents in cultured neurons have led to the identification of compounds classified as partial agonists, antagonists, and inverse agonists at the polyamine recognition site. Polyamines have also been found to affect the binding of ligands to the recognition sites for glutamate and glycine. However, these effects may be mediated at a site distinct from that at which polyamines act to modulate the binding of open-channel blockers. Endogenous polyamines may modulate excitatory synaptic transmission by acting at the polyamine recognition site of the NMDA receptor. This site could represent a novel therapeutic target for the treatment of ischemia-induced neurotoxicity, epilepsy, and neurodegenerative diseases.

  11. Anti-NMDA Receptor Encephalitis in the Polar Bear (Ursus maritimus) Knut

    PubMed Central

    Prüss, H.; Leubner, J.; Wenke, N. K.; Czirják, G. Á.; Szentiks, C. A.; Greenwood, A. D.

    2015-01-01

    Knut the polar bear of the Berlin Zoological Garden drowned in 2011 following seizures and was diagnosed as having suffered encephalitis of unknown etiology after exhaustive pathogen screening. Using the diagnostic criteria applied to human patients, we demonstrate that Knut’s encephalitis is almost identical to anti-NMDA receptor encephalitis which is a severe autoimmune disease representing the most common non-infectious encephalitis in humans. High concentrations of antibodies specific against the NR1 subunit of the NMDA receptor were detected in Knut’s cerebrospinal fluid. Histological examination demonstrated very similar patterns of plasma cell infiltration and minimal neuronal loss in affected brain areas. We conclude that Knut suffered anti-NMDA receptor encephalitis making his the first reported non-human case of this treatable disease. The results suggest that anti-NMDA receptor encephalitis may be a disease of broad relevance to mammals that until now has remained undiagnosed. PMID:26313569

  12. Anti-NMDA Receptor Encephalitis in the Polar Bear (Ursus maritimus) Knut.

    PubMed

    Prüss, H; Leubner, J; Wenke, N K; Czirják, G Á; Szentiks, C A; Greenwood, A D

    2015-01-01

    Knut the polar bear of the Berlin Zoological Garden drowned in 2011 following seizures and was diagnosed as having suffered encephalitis of unknown etiology after exhaustive pathogen screening. Using the diagnostic criteria applied to human patients, we demonstrate that Knut's encephalitis is almost identical to anti-NMDA receptor encephalitis which is a severe autoimmune disease representing the most common non-infectious encephalitis in humans. High concentrations of antibodies specific against the NR1 subunit of the NMDA receptor were detected in Knut's cerebrospinal fluid. Histological examination demonstrated very similar patterns of plasma cell infiltration and minimal neuronal loss in affected brain areas. We conclude that Knut suffered anti-NMDA receptor encephalitis making his the first reported non-human case of this treatable disease. The results suggest that anti-NMDA receptor encephalitis may be a disease of broad relevance to mammals that until now has remained undiagnosed. PMID:26313569

  13. Prolonged activation of NMDA receptors promotes dephosphorylation and alters postendocytic sorting of GABAB receptors

    PubMed Central

    Terunuma, Miho; Vargas, Karina J.; Wilkins, Megan E.; Ramírez, Omar A.; Jaureguiberry-Bravo, Matías; Pangalos, Menelas N.; Smart, Trevor G.; Moss, Stephen J.; Couve, Andrés

    2010-01-01

    Slow and persistent synaptic inhibition is mediated by metabotropic GABAB receptors (GABABRs). GABABRs are responsible for the modulation of neurotransmitter release from presynaptic terminals and for hyperpolarization at postsynaptic sites. Postsynaptic GABABRs are predominantly found on dendritic spines, adjacent to excitatory synapses, but the control of their plasma membrane availability is still controversial. Here, we explore the role of glutamate receptor activation in regulating the function and surface availability of GABABRs in central neurons. We demonstrate that prolonged activation of NMDA receptors (NMDA-Rs) leads to endocytosis, a diversion from a recycling route, and subsequent lysosomal degradation of GABABRs. These sorting events are paralleled by a reduction in GABABR-dependent activation of inwardly rectifying K+ channel currents. Postendocytic sorting is critically dependent on phosphorylation of serine 783 (S783) within the GABABR2 subunit, an established substrate of AMP-dependent protein kinase (AMPK). NMDA-R activation leads to a rapid increase in phosphorylation of S783, followed by a slower dephosphorylation, which results from the activity of AMPK and protein phosphatase 2A, respectively. Agonist activation of GABABRs counters the effects of NMDA. Thus, NMDA-R activation alters the phosphorylation state of S783 and acts as a molecular switch to decrease the abundance of GABABRs at the neuronal plasma membrane. Such a mechanism may be of significance during synaptic plasticity or pathological conditions, such as ischemia or epilepsy, which lead to prolonged activation of glutamate receptors. PMID:20643948

  14. Defining the role of NMDA receptors in anesthesia: are we there yet?

    PubMed

    Petrenko, Andrey B; Yamakura, Tomohiro; Sakimura, Kenji; Baba, Hiroshi

    2014-01-15

    N-methyl-d-aspartate (NMDA) receptors are important in mediating excitatory neurotransmission in the nervous system. They are preferentially inhibited by some general anesthetics and have, therefore, been implied in the mediation of their effects. This review summarizes the main research findings available related to NMDA receptors and their role in anesthesia. The contribution of NMDA receptors to the anesthetized state is discussed separately for each of its components: amnesia, analgesia, unconsciousness and immobility. Anesthetic-induced unconsciousness and immobility have received the most attention in the research community and are the main focus of this review. In the overall perspective, however, studies using pharmacological or electrophysiological approaches have failed to reach definitive conclusions regarding the contribution of NMDA receptors to these anesthetic endpoints. None of the studies have specifically addressed the role of NMDA receptors in the amnestic effect of general anesthetics, and the few available data are (at best) only indirect. NMDA receptor antagonism by general anesthetics may have a preventive anti-hyperalgesic effect. The only and most extensively used genetic tool to examine the role of NMDA receptors in anesthesia is global knockout of the GluN2A subunit of the NMDA receptor. These animals are resistant to many intravenous and inhalational anesthetics, but the interpretation of their phenotype is hindered by the secondary changes occurring in these animals after GluN2A knockout, which are themselves capable of altering anesthetic sensitivity. Generation of more sophisticated conditional knockout models targeting NMDA receptors is required to finally define their role in the mechanisms of anesthesia. PMID:24333550

  15. Alcohol Related Changes in Regulation of NMDA Receptor Functions

    PubMed Central

    Nagy, József

    2008-01-01

    Long-term alcohol exposure may lead to development of alcohol dependence in consequence of altered neurotransmitter functions. Accumulating evidence suggests that the N-methyl-D-aspartate (NMDA) type of glutamate receptors is a particularly important site of ethanol’s action. Several studies showed that ethanol potently inhibits NMDA receptors (NMDARs) and prolonged ethanol exposition leads to a compensatory “up-regulation” of NMDAR mediated functions. Therefore, alterations in NMDAR function are supposed to contribute to the development of ethanol tolerance, dependence as well as to the acute and late signs of ethanol withdrawal. A number of publications report alterations in the expression and phosphorylation states of NMDAR subunits, in their interaction with scaffolding proteins or other receptors in consequence of chronic ethanol treatment. Our knowledge on the regulatory processes, which modulate NMDAR functions including factors altering transcription, protein expression and post-translational modifications of NMDAR subunits, as well as those influencing their interactions with different regulatory proteins or other downstream signaling elements are incessantly increasing. The aim of this review is to summarize the complex chain of events supposedly playing a role in the up-regulation of NMDAR functions in consequence of chronic ethanol exposure. PMID:19305787

  16. Bacopa monnieri Extract (CDRI-08) Modulates the NMDA Receptor Subunits and nNOS-Apoptosis Axis in Cerebellum of Hepatic Encephalopathy Rats

    PubMed Central

    Mondal, Papia; Trigun, Surendra Kumar

    2015-01-01

    Hepatic encephalopathy (HE), characterized by impaired cerebellar functions during chronic liver failure (CLF), involves N-methyl-D-aspartate receptor (NMDAR) overactivation in the brain cells. Bacopa monnieri (BM) extract is a known neuroprotectant. The present paper evaluates whether BM extract is able to modulate the two NMDAR subunits (NR2A and NR2B) and its downstream mediators in cerebellum of rats with chronic liver failure (CLF), induced by administration of 50 mg/kg bw thioacetamide (TAA) i.p. for 14 days, and in the TAA group rats orally treated with 200 mg/kg bw BM extract from days 8 to 14. NR2A is known to impart neuroprotection and that of NR2B induces neuronal death during NMDAR activation. Neuronal nitric oxide synthase- (nNOS-) apoptosis pathway is known to mediate NMDAR led excitotoxicity. The level of NR2A was found to be significantly reduced with a concomitant increase of NR2B in cerebellum of the CLF rats. This was consistent with significantly enhanced nNOS expression, nitric oxide level, and reduced Bcl2/Bax ratio. Moreover, treatment with BM extract reversed the NR2A/NR2B ratio and also normalized the levels of nNOS-apoptotic factors in cerebellum of those rats. The findings suggest modulation of NR2A and NR2B expression by BM extract to prevent neurochemical alterations associated with HE. PMID:26413124

  17. A Naturally Occurring Null Variant of the NMDA Type Glutamate Receptor NR3B Subunit Is a Risk Factor of Schizophrenia

    PubMed Central

    Hashimoto, Ryota; Yamamori, Hidenaga; Yasuda, Yuka; Fujimoto, Michiko; Yano-Umeda, Satomi; Saneyoshi, Takeo; Takeda, Masatoshi; Hayashi, Yasunori

    2015-01-01

    Hypofunction of the N-methyl-D-aspartate type glutamate receptor (NMDAR) has been implicated in the pathogenesis of schizophrenia. Here, we investigated the significance of a common human genetic variation of the NMDAR NR3B subunit that inserts 4 bases within the coding region (insCGTT) in the pathogenesis of schizophrenia. The cDNA carrying this polymorphism generates a truncated protein, which is electrophysiologically non-functional in heterologous expression systems. Among 586 schizophrenia patients and 754 healthy controls, insCGTT was significantly overrepresented in patients compared to controls (odds ratio = 1.37, p = 0.035). Among 121 schizophrenia patients and 372 healthy controls, genetic analyses of normal individuals revealed that those carrying insCGTT have a predisposition to schizotypal personality traits (F1,356 = 4.69, p = 0.031). Furthermore, pre-pulse inhibition, a neurobiological trait disturbed in patients with schizophrenia, was significantly impaired in patients carrying insCGTT compared with those with the major allele (F1,116 = 5.72, p = 0.018, F1,238 = 4.46, p = 0.036, respectively). These results indicate that a naturally occurring null variant in NR3B could be a risk factor of schizophrenia. PMID:25768306

  18. The role of GluN2A and GluN2B NMDA receptor subunits in AgRP and POMC neurons on body weight and glucose homeostasis

    PubMed Central

    Üner, Aykut; Gonçalves, Gabriel H.M.; Li, Wenjing; Porceban, Matheus; Caron, Nicole; Schönke, Milena; Delpire, Eric; Sakimura, Kenji; Bjørbæk, Christian

    2015-01-01

    Objective Hypothalamic agouti-related peptide (AgRP) and pro-opiomelanocortin (POMC) expressing neurons play critical roles in control of energy balance. Glutamatergic input via n-methyl-d-aspartate receptors (NMDARs) is pivotal for regulation of neuronal activity and is required in AgRP neurons for normal body weight homeostasis. NMDARs typically consist of the obligatory GluN1 subunit and different GluN2 subunits, the latter exerting crucial differential effects on channel activity and neuronal function. Currently, the role of specific GluN2 subunits in AgRP and POMC neurons on whole body energy and glucose balance is unknown. Methods We used the cre-lox system to genetically delete GluN2A or GluN2B only from AgRP or POMC neurons in mice. Mice were then subjected to metabolic analyses and assessment of AgRP and POMC neuronal function through morphological studies. Results We show that loss of GluN2B from AgRP neurons reduces body weight, fat mass, and food intake, whereas GluN2B in POMC neurons is not required for normal energy balance control. GluN2A subunits in either AgRP or POMC neurons are not required for regulation of body weight. Deletion of GluN2B reduces the number of AgRP neurons and decreases their dendritic length. In addition, loss of GluN2B in AgRP neurons of the morbidly obese and severely diabetic leptin-deficient Lepob/ob mice does not affect body weight and food intake but, remarkably, leads to full correction of hyperglycemia. Lepob/ob mice lacking GluN2B in AgRP neurons are also more sensitive to leptin's anti-obesity actions. Conclusions GluN2B-containing NMDA receptors in AgRP neurons play a critical role in central control of body weight homeostasis and blood glucose balance via mechanisms that likely involve regulation of AgRP neuronal survival and structure, and modulation of hypothalamic leptin action. PMID:26500840

  19. NMDA receptor properties in rat supraoptic magnocellular neurons: characterization and postnatal development.

    PubMed

    Hussy, N; Boissin-Agasse, L; Richard, P; Desarménien, M G

    1997-07-01

    Hypothalamo-neurohypophysial magnocellular neurons display specific electrical activities in relation to the mode of release of their hormonal content (vasopressin or oxytocin). These activities are under strong glutamatergic excitatory control. The implication of NMDA receptors in the control of vasopressinergic and oxytocinergic neurons is still a matter of debate. We here report the first detailed characterization of functional properties of NMDA receptors in voltage-clamped magnocellular neurons acutely dissociated from the supraoptic nucleus. All cells responded to NMDA with currents that reversed polarity around 0 mV and were inhibited by D-2-amino-5-phosphonovalerate (D-APV) and by 100 microM extracellular Mg2+ (at -80 mV). Sensitivity to the co-agonist glycine (EC50, 2 microM) was low compared with most other neuronal preparations. The receptors displayed low sensitivity to ifenprodil, were insensitive to glycine-independent potentiation by spermine, and had a unitary conductance of 50 pS. No evidence was found for two distinct cell populations, suggesting that oxytocinergic and vasopressinergic neurons express similar NMDA receptors. Characterization of NMDA receptors at different postnatal ages revealed a transient increase in density of NMDA currents during the second postnatal week. This was accompanied by a specific decrease in sensitivity to D-APV, with no change in NMDA sensitivity or any other properties studied. Supraoptic NMDA receptors thus present characteristics that strikingly resemble those of reconstituted receptors composed of NR1 and NR2A subunits. Understanding the functional significance of the development of NMDA receptors in the supraoptic nucleus will require further knowledge about the maturation of neuronal excitability, synaptic connections and neurohormone release mechanisms. PMID:9240401

  20. Traxoprodil, a selective antagonist of the NR2B subunit of the NMDA receptor, potentiates the antidepressant-like effects of certain antidepressant drugs in the forced swim test in mice.

    PubMed

    Poleszak, Ewa; Stasiuk, Weronika; Szopa, Aleksandra; Wyska, Elżbieta; Serefko, Anna; Oniszczuk, Anna; Wośko, Sylwia; Świąder, Katarzyna; Wlaź, Piotr

    2016-08-01

    One of the newest substances, whose antidepressant activity was shown is traxoprodil, which is a selective antagonist of the NR2B subunit of the NMDA receptor. The main goal of the present study was to evaluate the effect of traxoprodil on animals' behavior using the forced swim test (FST), as well as the effect of traxoprodil (10 mg/kg) on the activity of antidepressants, such as imipramine (15 mg/kg), fluoxetine (5 mg/kg), escitalopram (2 mg/kg) and reboxetine (2.5 mg/kg). Serotonergic lesion and experiment using the selective agonists of serotonin receptors 5-HT1A and 5-HT2 was conducted to evaluate the role of the serotonergic system in the antidepressant action of traxoprodil. Brain concentrations of tested agents were determined using HPLC. The results showed that traxoprodil at a dose of 20 and 40 mg/kg exhibited antidepressant activity in the FST and it was not related to changes in animals' locomotor activity. Co-administration of traxoprodil with imipramine, fluoxetine or escitalopram, each in subtherapeutic doses, significantly affected the animals' behavior in the FST and, what is important, these changes were not due to the severity of locomotor activity. The observed effect of traxoprodil is only partially associated with serotonergic system and is independent of the effect on the 5-HT1A and 5-HT2 serotonin receptors. The results of an attempt to assess the nature of the interaction between traxoprodil and the tested drugs show that in the case of joint administration of traxoprodil and fluoxetine, imipramine or escitalopram, there were interactions in the pharmacokinetic phase. PMID:26924124

  1. Modulation of protein tyrosine phosphatase activity alters the subunit assembly in native N-methyl-D-aspartate receptor complex.

    PubMed

    Ferrani-Kile, Karima; Leslie, Steven W

    2005-07-01

    The N-methyl-D-aspartate (NMDA) receptor is crucial for development and neuroplasticity as well as excitotoxicity. The biochemical basis of the disassembly and reassembly of NMDA receptor has never been reported. Using coimmunoprecipitation, Western blotting, and mass spectrometry, we show that inhibition of tyrosine phosphatases triggers disassembly of NR1, NR2A, and NR2B in cortical NMDA receptor complexes. Furthermore, the disassembly of the NMDA receptor subunits is immediate, dose-dependent, and reversible and seems to occur through mechanisms linked to Src kinases. Together, these results define a novel role for tyrosine phosphatases in the complex mechanism of NMDA receptor regulation. PMID:15837820

  2. Evolution of NMDA receptor cytoplasmic interaction domains: implications for organisation of synaptic signalling complexes

    PubMed Central

    Ryan, Tomás J; Emes, Richard D; Grant, Seth GN; Komiyama, Noboru H

    2008-01-01

    Background Glutamate gated postsynaptic receptors in the central nervous system (CNS) are essential for environmentally stimulated behaviours including learning and memory in both invertebrates and vertebrates. Though their genetics, biochemistry, physiology, and role in behaviour have been intensely studied in vitro and in vivo, their molecular evolution and structural aspects remain poorly understood. To understand how these receptors have evolved different physiological requirements we have investigated the molecular evolution of glutamate gated receptors and ion channels, in particular the N-methyl-D-aspartate (NMDA) receptor, which is essential for higher cognitive function. Studies of rodent NMDA receptors show that the C-terminal intracellular domain forms a signalling complex with enzymes and scaffold proteins, which is important for neuronal and behavioural plasticity Results The vertebrate NMDA receptor was found to have subunits with C-terminal domains up to 500 amino acids longer than invertebrates. This extension was specific to the NR2 subunit and occurred before the duplication and subsequent divergence of NR2 in the vertebrate lineage. The shorter invertebrate C-terminus lacked vertebrate protein interaction motifs involved with forming a signaling complex although the terminal PDZ interaction domain was conserved. The vertebrate NR2 C-terminal domain was predicted to be intrinsically disordered but with a conserved secondary structure. Conclusion We highlight an evolutionary adaptation specific to vertebrate NMDA receptor NR2 subunits. Using in silico methods we find that evolution has shaped the NMDA receptor C-terminus into an unstructured but modular intracellular domain that parallels the expansion in complexity of an NMDA receptor signalling complex in the vertebrate lineage. We propose the NR2 C-terminus has evolved to be a natively unstructured yet flexible hub organising postsynaptic signalling. The evolution of the NR2 C-terminus and its

  3. Signaling Cascades Regulating NMDA Receptor Sensitivity to Ethanol

    PubMed Central

    RON, DORIT

    2005-01-01

    One of the major targets for ethanol (alcohol) in the brain is the N-methyl-d-aspartate (NMDA) receptor, a glutamate-gated ion channel. Intriguingly, the effects of ethanol on the NMDA receptor are not homogeneous throughout the brain. This review focuses on recent studies revealing molecular mechanisms that mediate the actions of ethanol on the NMDA receptor in different brain regions via changes in NMDA receptor phosphorylation and compartmentalization. Specifically, the role of the scaffolding protein RACK1 and the regulatory protein DARPP-32 in mediating the distinct effects of ethanol is presented. PMID:15271260

  4. NMDA receptor binding in focal epilepsies

    PubMed Central

    McGinnity, C J; Koepp, M J; Hammers, A; Riaño Barros, D A; Pressler, R M; Luthra, S; Jones, P A; Trigg, W; Micallef, C; Symms, M R; Brooks, D J; Duncan, J S

    2015-01-01

    Objective To demonstrate altered N-methyl-d-aspartate (NMDA) receptor availability in patients with focal epilepsies using positron emission tomography (PET) and [18F]GE-179, a ligand that selectively binds to the open NMDA receptor ion channel, which is thought to be overactive in epilepsy. Methods Eleven patients (median age 33 years, 6 males) with known frequent interictal epileptiform discharges had an [18F]GE-179 PET scan, in a cross-sectional study. MRI showed a focal lesion but discordant EEG changes in two, was non-localising with multifocal EEG abnormalities in two, and was normal in the remaining seven patients who all had multifocal EEG changes. Individual patient [18F]GE-179 volume-of-distribution (VT) images were compared between individual patients and a group of 10 healthy controls (47 years, 7 males) using Statistical Parametric Mapping. Results Individual analyses revealed a single cluster of focal VT increase in four patients; one with a single and one with multifocal MRI lesions, and two with normal MRIs. Post hoc analysis revealed that, relative to controls, patients not taking antidepressants had globally increased [18F]GE-179 VT (+28%; p<0.002), and the three patients taking an antidepressant drug had globally reduced [18F]GE-179 VT (−29%; p<0.002). There were no focal abnormalities common to the epilepsy group. Conclusions In patients with focal epilepsies, we detected primarily global increases of [18F]GE-179 VT consistent with increased NMDA channel activation, but reduced availability in those taking antidepressant drugs, consistent with a possible mode of action of this class of drugs. [18F]GE-179 PET showed focal accentuations of NMDA binding in 4 out of 11 patients, with difficult to localise and treat focal epilepsy. PMID:25991402

  5. Role of motor cortex NMDA receptors in learning-dependent synaptic plasticity of behaving mice.

    PubMed

    Hasan, Mazahir T; Hernández-González, Samuel; Dogbevia, Godwin; Treviño, Mario; Bertocchi, Ilaria; Gruart, Agnès; Delgado-García, José M

    2013-01-01

    The primary motor cortex has an important role in the precise execution of learned motor responses. During motor learning, synaptic efficacy between sensory and primary motor cortical neurons is enhanced, possibly involving long-term potentiation and N-methyl-D-aspartate (NMDA)-specific glutamate receptor function. To investigate whether NMDA receptor in the primary motor cortex can act as a coincidence detector for activity-dependent changes in synaptic strength and associative learning, here we generate mice with deletion of the Grin1 gene, encoding the essential NMDA receptor subunit 1 (GluN1), specifically in the primary motor cortex. The loss of NMDA receptor function impairs primary motor cortex long-term potentiation in vivo. Importantly, it impairs the synaptic efficacy between the primary somatosensory and primary motor cortices and significantly reduces classically conditioned eyeblink responses. Furthermore, compared with wild-type littermates, mice lacking NMDA receptors in the [corrected] primary motor cortex show slower learning in Skinner-box tasks. Thus, primary motor cortex NMDA receptors are necessary for activity-dependent synaptic strengthening and associative learning. PMID:23978820

  6. Both NR2A and NR2B Subunits of the NMDA Receptor Are Critical for Long-Term Potentiation and Long-Term Depression in the Lateral Amygdala of Horizontal Slices of Adult Mice

    ERIC Educational Resources Information Center

    Muller, Tobias; Albrecht, Doris; Gebhardt, Christine

    2009-01-01

    The lateral nucleus of the amygdala (LA) is implicated in emotional and social behaviors. We recently showed that in horizontal brain slices, activation of NMDA receptors (NMDARs) is a requirement for persistent synaptic alterations in the LA, such as long-term potentiation (LTP) and long-term depression (LTD). In the LA, NR2A- and NR2B-type NMDRs…

  7. Neonatal NMDA Receptor Blockade Disrupts Spike Timing and Glutamatergic Synapses in Fast Spiking Interneurons in a NMDA Receptor Hypofunction Model of Schizophrenia

    PubMed Central

    Jones, Kevin S.; Corbin, Joshua G.; Huntsman, Molly M.

    2014-01-01

    The dysfunction of parvalbumin-positive, fast-spiking interneurons (FSI) is considered a primary contributor to the pathophysiology of schizophrenia (SZ), but deficits in FSI physiology have not been explicitly characterized. We show for the first time, that a widely-employed model of schizophrenia minimizes first spike latency and increases GluN2B-mediated current in neocortical FSIs. The reduction in FSI first-spike latency coincides with reduced expression of the Kv1.1 potassium channel subunit which provides a biophysical explanation for the abnormal spiking behavior. Similarly, the increase in NMDA current coincides with enhanced expression of the GluN2B NMDA receptor subunit, specifically in FSIs. In this study mice were treated with the NMDA receptor antagonist, MK-801, during the first week of life. During adolescence, we detected reduced spike latency and increased GluN2B-mediated NMDA current in FSIs, which suggests transient disruption of NMDA signaling during neonatal development exerts lasting changes in the cellular and synaptic physiology of neocortical FSIs. Overall, we propose these physiological disturbances represent a general impairment to the physiological maturation of FSIs which may contribute to schizophrenia-like behaviors produced by this model. PMID:25290690

  8. NAAG, NMDA receptor and psychosis.

    PubMed

    Bergeron, Richard; Coyle, Joseph T

    2012-01-01

    At central synapses, glutamate is the main excitatory neurotransmitter. Once released from presynaptic terminals, glutamate activates a number of different glutamatergic receptors one of which is the ligand gated ionophore glutamatergic subtype N-methyl-D-aspartate receptors (NMDARs). NMDARs play a crucial role in controlling various determinants of synaptic function. N-acetylaspartylglutamate (NAAG) is the most prevalent peptide transmitter in the mammalian central nervous system. NAAG is released upon neuronal depolarization by a calcium-dependent process from glutamatergic and GABAergic neurons. It is cleaved by a specific peptidase located on astrocytes, glutamate carboxypeptidase type II (GCP-II), to N-acetylaspartate (NAA) and glutamate. Current evidence supports the hypothesis that NAAG is an endogenous agonist at G protein coupled mGluR3 receptors and an antagonist at NMDAR. In several disorders and animal models of human diseases, the levels of NAAG and the activity of GCP-II are altered in ways that are consistent with NAAG's role in regulation of glutamatergic neurotransmission. Several lines of evidence suggest that a dysfunction in glutamatergic via the NMDAR might be involved in schizophrenia. This hypothesis has evolved from findings that NMDAR antagonists such as phencyclidine (PCP or "angel dust"), produces a syndrome in normal individuals that closely resembles schizophrenia and exacerbates psychotic symptoms in patients with chronic schizophrenia. Recent postmortem, metabolic and genetic studies have provided evidence that hypofunction of discrete populations of NMDAR can contribute to the symptoms of schizophrenia, at least in some patients. The review outlines the role of endogenous NAAG at NMDAR neurotransmission and its putative role in the pathophysiology of schizophrenia. PMID:22304714

  9. An NMDA receptor-dependent mechanism underlies inhibitory synapse development

    PubMed Central

    Gu, Xinglong; Zhou, Liang; Lu, Wei

    2016-01-01

    Summary In the mammalian brain GABAergic synaptic transmission provides inhibitory balance to glutamatergic excitatory drive and controls neuronal output. The molecular mechanisms underlying the development of GABAergic synapses remain largely unclear. Here we report that NMDA-type ionotropic glutamate receptors (NMDARs) in individual immature neurons are the upstream signaling molecules essential for GABAergic synapse development, which requires signaling via Calmodulin binding motif in the C0 domain of the NMDAR GluN1 subunit. Interestingly, in neurons lacking NMDARs, while GABAergic synaptic transmission is strongly reduced, the tonic inhibition mediated by extrasynaptic GABAA receptors is increased, suggesting a compensatory mechanism for the lack of synaptic inhibition. These results demonstrate a crucial role for NMDARs in specifying the development of inhibitory synapses, and suggest an important mechanism for controlling the establishment of the balance between synaptic excitation and inhibition in the developing brain. PMID:26774487

  10. Noncompetitive, Voltage-Dependent NMDA Receptor Antagonism by Hydrophobic Anions

    PubMed Central

    Linsenbardt, Andrew J.; Chisari, Mariangela; Yu, Andrew; Shu, Hong-Jin; Zorumski, Charles F.

    2013-01-01

    NMDA receptor (NMDAR) antagonists are dissociative anesthetics, drugs of abuse, and are of therapeutic interest in neurodegeneration and neuropsychiatric disease. Many well-known NMDAR antagonists are positively charged, voltage-dependent channel blockers. We recently showed that the hydrophobic anion dipicrylamine (DPA) negatively regulates GABAA receptor function by a mechanism indistinguishable from that of sulfated neurosteroids. Because sulfated neurosteroids also modulate NMDARs, here we examined the effects of DPA on NMDAR function. In rat hippocampal neurons DPA inhibited currents gated by 300 µM NMDA with an IC50 of 2.3 µM. Neither onset nor offset of antagonism exhibited dependence on channel activation but exhibited a noncompetitive profile. DPA antagonism was independent of NMDAR subunit composition and was similar at extrasynaptic and total receptor populations. Surprisingly, similar to cationic channel blockers but unlike sulfated neurosteroids, DPA antagonism was voltage dependent. Onset and offset of DPA antagonism were nearly 10-fold faster than DPA-induced increases in membrane capacitance, suggesting that membrane interactions do not directly explain antagonism. Furthermore, voltage dependence did not derive from association of DPA with a site on NMDARs directly accessible to the outer membrane leaflet, assessed by DPA translocation experiments. Consistent with the expected lack of channel block, DPA antagonism did not interact with permeant ions. Therefore, we speculate that voltage dependence may arise from interactions of DPA with the inherent voltage dependence of channel gating. Overall, we conclude that DPA noncompetitively inhibits NMDA-induced current by a novel voltage-dependent mechanism and represents a new class of anionic NMDAR antagonists. PMID:23144238

  11. NMDA Receptor Modulators in the Treatment of Drug Addiction

    PubMed Central

    Tomek, Seven E.; LaCrosse, Amber L.; Nemirovsky, Natali E.; Olive, M. Foster

    2013-01-01

    Glutamate plays a pivotal role in drug addiction, and the N-methyl-d-aspartate (NMDA) glutamate receptor subtype serves as a molecular target for several drugs of abuse. In this review, we will provide an overview of NMDA receptor structure and function, followed by a review of the mechanism of action, clinical efficacy, and side effect profile of NMDA receptor ligands that are currently in use or being explored for the treatment of drug addiction. These ligands include the NMDA receptor modulators memantine and acamprosate, as well as the partial NMDA agonist d-Cycloserine. Data collected to date suggest that direct NMDA receptor modulators have relatively limited efficacy in the treatment of drug addiction, and that partial agonism of NMDA receptors may have some efficacy with regards to extinction learning during cue exposure therapy. However, the lack of consistency in results to date clearly indicates that additional studies are needed, as are studies examining novel ligands with indirect mechanisms for altering NMDA receptor function. PMID:24275950

  12. Three-dimensional models of non-NMDA glutamate receptors.

    PubMed Central

    Sutcliffe, M J; Wo, Z G; Oswald, R E

    1996-01-01

    Structural models have been produced for three types of non-NMDA inotropic glutamate receptors: an AMPA receptor, GluR1, a kainate receptor, GluR6; and a low-molecular-weight kainate receptor from goldfish, GFKAR alpha. Modeling was restricted to the domains of the proteins that bind the neurotransmitter glutamate and that form the ion channel. Model building combined homology modeling, distance geometry, molecular mechanics, interactive modeling, and known constraints. The models indicate new potential interactions in the extracellular domain between protein and agonists, and suggest that the transition from the "closed" to the "open" state involves the movement of a conserved positive residue away from, and two conserved negative residues into, the extracellular entrance to the pore upon binding. As a first approximation, the ion channel domain was modeled with a structure comprising a central antiparallel beta-barrel that partially crosses the membrane, and against which alpha-helices from each subunit are packed; a third alpha-helix packs against these two helices in each subunit. Much, but not all, of the available data were consistent with this structure. Modifying the beta-barrel to a loop-like topology produced a model consistent with available data. Images FIGURE 1 FIGURE 2 FIGURE 3 FIGURE 4 FIGURE 5 FIGURE 7 PMID:8785317

  13. Neutrophil depletion after subarachnoid hemorrhage improves memory via NMDA receptors.

    PubMed

    Provencio, Jose Javier; Swank, Valerie; Lu, Haiyan; Brunet, Sylvain; Baltan, Selva; Khapre, Rohini V; Seerapu, Himabindu; Kokiko-Cochran, Olga N; Lamb, Bruce T; Ransohoff, Richard M

    2016-05-01

    Cognitive deficits after aneurysmal subarachnoid hemorrhage (SAH) are common and disabling. Patients who experience delayed deterioration associated with vasospasm are likely to have cognitive deficits, particularly problems with executive function, verbal and spatial memory. Here, we report neurophysiological and pathological mechanisms underlying behavioral deficits in a murine model of SAH. On tests of spatial memory, animals with SAH performed worse than sham animals in the first week and one month after SAH suggesting a prolonged injury. Between three and six days after experimental hemorrhage, mice demonstrated loss of late long-term potentiation (L-LTP) due to dysfunction of the NMDA receptor. Suppression of innate immune cell activation prevents delayed vasospasm after murine SAH. We therefore explored the role of neutrophil-mediated innate inflammation on memory deficits after SAH. Depletion of neutrophils three days after SAH mitigates tissue inflammation, reverses cerebral vasoconstriction in the middle cerebral artery, and rescues L-LTP dysfunction at day 6. Spatial memory deficits in both the short and long-term are improved and associated with a shift of NMDA receptor subunit composition toward a memory sparing phenotype. This work supports further investigating suppression of innate immunity after SAH as a target for preventative therapies in SAH. PMID:26872422

  14. Oligodendroglial NMDA Receptors Regulate Glucose Import and Axonal Energy Metabolism.

    PubMed

    Saab, Aiman S; Tzvetavona, Iva D; Trevisiol, Andrea; Baltan, Selva; Dibaj, Payam; Kusch, Kathrin; Möbius, Wiebke; Goetze, Bianka; Jahn, Hannah M; Huang, Wenhui; Steffens, Heinz; Schomburg, Eike D; Pérez-Samartín, Alberto; Pérez-Cerdá, Fernando; Bakhtiari, Davood; Matute, Carlos; Löwel, Siegrid; Griesinger, Christian; Hirrlinger, Johannes; Kirchhoff, Frank; Nave, Klaus-Armin

    2016-07-01

    Oligodendrocytes make myelin and support axons metabolically with lactate. However, it is unknown how glucose utilization and glycolysis are adapted to the different axonal energy demands. Spiking axons release glutamate and oligodendrocytes express NMDA receptors of unknown function. Here we show that the stimulation of oligodendroglial NMDA receptors mobilizes glucose transporter GLUT1, leading to its incorporation into the myelin compartment in vivo. When myelinated optic nerves from conditional NMDA receptor mutants are challenged with transient oxygen-glucose deprivation, they show a reduced functional recovery when returned to oxygen-glucose but are indistinguishable from wild-type when provided with oxygen-lactate. Moreover, the functional integrity of isolated optic nerves, which are electrically silent, is extended by preincubation with NMDA, mimicking axonal activity, and shortened by NMDA receptor blockers. This reveals a novel aspect of neuronal energy metabolism in which activity-dependent glutamate release enhances oligodendroglial glucose uptake and glycolytic support of fast spiking axons. PMID:27292539

  15. Treadmill exercise enhances NMDA receptor expression in schizophrenia mice

    PubMed Central

    Park, Joon-Ki; Lee, Sam-Jun; Kim, Tae-Won

    2014-01-01

    Schizophrenia is a serious psychiatric disorder with several symptoms including cognitive dysfunction. Although the causes of schizophrenia are still unclear, there is a strong suspicion that the abnormality in N-methyl-D-aspartate (NMDA) receptor may contribute to schizophrenia symptoms. In the present study, the effect of treadmill exercise on the NMDA receptor expression was evaluated using MK-801-induced schizophrenia mice. Immunohistochemistry for expressions of NMDA receptor tyrosine hydroxylase (TH) was conducted. Western blot for brain-derived neurotrophic factor (BDNF) was also performed. In the present results, the mice in the MK-801-treated group displayed reduced NMDA receptor expression. Enhanced TH expression and suppressed BDNF expression were also observed in the MK-801-treated mice. Treadmill exercise improved NMDA receptor expression in the MK-801-induced schizophrenia mice. Treadmill exercise also suppressed TH expression and enhanced BDNF expression in the MK-801-induced schizophrenia mice. The present study showed that down-regulation of NMDA receptor demonstrated schizophrenia-like parameters, meanwhile treadmill running improved schizophrenia-related parameters through enhancing NMDA receptor expression. PMID:24678500

  16. Actions of Bupivacaine, a Widely Used Local Anesthetic, on NMDA Receptor Responses

    PubMed Central

    Paganelli, Meaghan A.

    2015-01-01

    NMDA receptors mediate excitatory neurotransmission in brain and spinal cord and play a pivotal role in the neurological disease state of chronic pain, which is caused by central sensitization. Bupivacaine is the indicated local anesthetic in caudal, epidural, and spinal anesthesia and is widely used clinically to manage acute and chronic pain. In addition to blocking Na+ channels, bupivacaine affects the activity of many other channels, including NMDA receptors. Importantly, bupivacaine inhibits NMDA receptor-mediated synaptic transmission in the dorsal horn of the spinal cord, an area critically involved in central sensitization. We used recombinant NMDA receptors expressed in HEK293 cells and found that increasing concentrations of bupivacaine decreased channel open probability in GluN2 subunit- and pH-independent manner by increasing the mean duration of closures and decreasing the mean duration of openings. Using kinetic modeling of one-channel currents, we attributed the observed current decrease to two main mechanisms: a voltage-dependent “foot-in-the-door” pore block and an allosteric gating effect. Further, the inhibition was state-independent because it occurred to the same degree whether the drug was applied before or after glutamate stimulation and was mediated by extracellular and intracellular inhibitory sites, via hydrophilic and hydrophobic pathways. These results predict that clinical doses of bupivacaine would decrease the peak and accelerate the decay of synaptic NMDA receptor currents during normal synaptic transmission. These quantitative predictions inform possible applications of bupivacaine as preventative and therapeutic approaches in chronic pain. PMID:25589775

  17. Role of motor cortex NMDA receptors in learning-dependent synaptic plasticity of behaving mice

    PubMed Central

    Hasan, Mazahir T.; Hernández-González, Samuel; Dogbevia, Godwin; Treviño, Mario; Bertocchi, Ilaria; Gruart, Agnès; Delgado-García, José M.

    2013-01-01

    The primary motor cortex has an important role in the precise execution of learned motor responses. During motor learning, synaptic efficacy between sensory and primary motor cortical neurons is enhanced, possibly involving long-term potentiation and N-methyl-D-aspartate (NMDA)-specific glutamate receptor function. To investigate whether NMDA receptor in the primary motor cortex can act as a coincidence detector for activity-dependent changes in synaptic strength and associative learning, here we generate mice with deletion of the Grin1 gene, encoding the essential NMDA receptor subunit 1 (GluN1), specifically in the primary motor cortex. The loss of NMDA receptor function impairs primary motor cortex long-term potentiation in vivo. Importantly, it impairs the synaptic efficacy between the primary somatosensory and primary motor cortices and significantly reduces classically conditioned eyeblink responses. Furthermore, compared with wild-type littermates, mice lacking primary motor cortex show slower learning in Skinner-box tasks. Thus, primary motor cortex NMDA receptors are necessary for activity-dependent synaptic strengthening and associative learning. PMID:23978820

  18. NMDA receptor antagonists attenuate the proconvulsant effect of juvenile social isolation in male mice.

    PubMed

    Amiri, Shayan; Haj-Mirzaian, Arya; Amini-Khoei, Hossein; Momeny, Majid; Shirzadian, Armin; Balaei, Maryam Rahimi; Zarrinrad, Ghazaleh; Ghazi-Khansari, Mahmoud; Azizi, Romina; Dehpour, Ahmad Reza; Mehr, Shahram Ejtemaei

    2016-03-01

    Experiencing psychosocial stress in early life, such as social isolation stress (SIS), is known to have negative enduring effects on the development of the brain and behavior. In addition to anxiety and depressive-like behaviors, we previously showed that juvenile SIS increases susceptibility to pentylenetetrazole (PTZ)-induced seizures in mice through enhancing the nitrergic system activity in the hippocampus. In this study, we investigated the possible involvement of N-methyl-d-aspartate (NMDA) receptors in proconvulsant effects of juvenile SIS. Applying 4 weeks of SIS to juvenile male mice at postnatal day 21-23, we observed an increased susceptibility to PTZ as well as anxiety and depressive-like behaviors in adult mice. Intraperitoneal (i.p.) administration of NMDA receptor antagonists, MK-801 (0.05mg/kg) and ketamine (0.5mg/kg), reversed the proconvulsant effects of SIS in Isolated (and not social) housed animals. Co-administration of non-effective doses of nitric oxide synthase (NOS) inhibitors, 7NI (25mg/kg) and L-NAME (10mg/kg), with NMDA receptor antagonists, MK-801 (0.01mg/kg) and ketamine (0.1mg/kg) attenuated the proconvulsant effects of juvenile SIS only in isolated housed mice. Also, using real time RT-PCR, we showed that hippocampal upregulation of NR2B subunit of NMDA receptor may play a critical role in proconvulsant effects of juvenile SIS by dysregulation of NMDA/NO pathway. In conclusion, results of present study revealed that experiencing SIS during adolescence predisposes the co-occurrence of seizure disorders with psychiatric comorbidities and also, alteration of NMDA receptor structure and function in hippocampus plays a role in proconvulsant effects of juvenile SIS through enhancing the NMDA/NO pathway. PMID:26836272

  19. NMDA and non-NMDA glutamate receptors in auditory transmission in the barn owl inferior colliculus.

    PubMed

    Feldman, D E; Knudsen, E I

    1994-10-01

    The pharmacology of auditory responses in the inferior colliculus (IC) of the barn owl was investigated by iontophoresis of excitatory amino acid receptor antagonists into two different functional subdivisions of the IC, the external nucleus (ICx) and the lateral shell of the central nucleus (lateral shell), both of which carry out important computations in the processing of auditory spatial information. Combined application of the NMDA receptor antagonist 2-amino-5-phosphonovaleric acid (AP5) and the non-NMDA receptor antagonist 6-cyano-5-nitroquinoxaline-2,3-dione (CNQX) significantly reduced auditory-evoked spikes at all sites in these two subdivisions, and completely eliminated responses at many locations. This suggests that excitatory amino acid receptors mediate the bulk, if not all, of auditory responses in the ICx and lateral shell. NMDA and non-NMDA receptors contributed differently to auditory responses in the two subdivisions. In the ICx, AP5 significantly reduced the number of auditory-evoked spikes at every site tested. On average, AP5 eliminated 55% of auditory-evoked spikes at multiunit sites and 64% at single-unit sites in this structure. In contrast, in the lateral shell, AP5 significantly reduced responses at less than half the sites tested, and, on average, AP5 eliminated only 19% of spikes at multiunit sites and 25% at single-unit sites. When the magnitude of response blockade produced by AP5 at individual multiunit sites was normalized to adjust for site-to-site differences in the efficacy of iontophoresed AP5 and CNQX, AP5 blockade was still significantly greater in the ICx than the lateral shell. CNQX application strongly reduced responses in both subdivisions. These data suggest that NMDA receptor currents make a major contribution to auditory responses in the ICx, while they make only a small contribution to auditory responses in the lateral shell. Non-NMDA receptor currents, on the other hand, contribute to auditory responses in both

  20. A conserved structural mechanism of NMDA receptor inhibition: A comparison of ifenprodil and zinc

    PubMed Central

    Sirrieh, Rita E.; MacLean, David M.

    2015-01-01

    N-methyl-d-aspartate (NMDA) receptors, one of the three main types of ionotropic glutamate receptors (iGluRs), are involved in excitatory synaptic transmission, and their dysfunction is implicated in various neurological disorders. NMDA receptors, heterotetramers typically composed of GluN1 and GluN2 subunits, are the only members of the iGluR family that bind allosteric modulators at their amino-terminal domains (ATDs). We used luminescence resonance energy transfer to characterize the conformational changes the receptor undergoes upon binding ifenprodil, a synthetic compound that specifically inhibits activation of NMDA receptors containing GluN2B. We found that ifenprodil induced an overall closure of the GluN2B ATD without affecting conformation of the GluN1 ATD or the upper lobes of the ATDs, the same mechanism whereby zinc inhibits GluN2A. These data demonstrate that the conformational changes induced by zinc and ifenprodil represent a conserved mechanism of NMDA receptor inhibition. Additionally, we compared the structural mechanism of zinc inhibition of GluN1–GluN2A receptors to that of ifenprodil inhibition of GluN1–GluN2B. The similarities in the conformational changes induced by inhibitor binding suggest a conserved structural mechanism of inhibition independent of the binding site of the modulator. PMID:26170175

  1. The NMDA receptor functions independently and as an LRP1 co-receptor to promote Schwann cell survival and migration.

    PubMed

    Mantuano, Elisabetta; Lam, Michael S; Shibayama, Masataka; Campana, W Marie; Gonias, Steven L

    2015-09-15

    NMDA receptors (NMDA-Rs) are ionotropic glutamate receptors, which associate with LDL-receptor-related protein-1 (LRP1) to trigger cell signaling in response to protein ligands in neurons. Here, we demonstrate for the first time that the NMDA-R is expressed by rat Schwann cells and functions independently and with LRP1 to regulate Schwann cell physiology. The NR1 (encoded by GRIN1) and NR2b (encoded by GRIN2B) NMDA-R subunits were expressed by cultured Schwann cells and upregulated in sciatic nerves following crush injury. The ability of LRP1 ligands to activate ERK1/2 (also known as MAPK3 and MAPK1, respectively) and promote Schwann cell migration required the NMDA-R. NR1 gene silencing compromised Schwann cell survival. Injection of the LRP1 ligands tissue-type plasminogen activator (tPA, also known as PLAT) or MMP9-PEX into crush-injured sciatic nerves activated ERK1/2 in Schwann cells in vivo, and the response was blocked by systemic treatment with the NMDA-R inhibitor MK801. tPA was unique among the LRP1 ligands examined because tPA activated cell signaling and promoted Schwann cell migration by interacting with the NMDA-R independently of LRP1, albeit with delayed kinetics. These results define the NMDA-R as a Schwann cell signaling receptor for protein ligands and a major regulator of Schwann cell physiology, which may be particularly important in peripheral nervous system (PNS) injury. PMID:26272917

  2. Potencies and unblocking kinetic properties of antagonists at recombinant human NMDA receptors in a Xenopus oocytes model.

    PubMed

    Heusler, Peter; Tourette, Amélie; Cussac, Didier

    2015-05-01

    N-methyl-D-aspartate (NMDA) receptor channels are implicated in a wide range of physiological and pathophysiological processes, and a large number of pharmacological agents have been introduced that target the receptor via diverse mechanisms of action. Amongst others, subunit selectivity (in particular for the NR2B receptor subunit) and rapid unblocking kinetics have been put forward as favourable pharmacological properties of NMDA receptor-targeting drugs. Here, we describe a pharmacological characterization of human recombinant NMDA receptors expressed in Xenopus oocytes in an electrophysiological set-up. Using this approach, we compare inhibitor potencies of several known NMDA receptor ligands as well as unblocking kinetic properties of selected compounds. All compounds tested had similar potencies at receptors containing NR2A or NR2B receptors with the exception of traxoprodil, which was selective for NR2B. The rank order of potency was (+)MK-801 > phencyclidine (PCP) ≈ traxoprodil > memantine ≈ ketamine > duloxetine. In line with its proposed rapid dissociation properties, the relatively well-tolerated drug memantine exhibits markedly faster unblocking than ketamine and PCP, similar to the low-affinity compound, duloxetine. Electrophysiological recording in Xenopus oocytes thus allows a relatively convenient comparison of key pharmacological parameters at recombinant human NMDA receptors. PMID:25604077

  3. Non-NMDA receptor antagonist-induced drinking in rat

    NASA Technical Reports Server (NTRS)

    Xu, Z.; Johnson, A. K.

    1998-01-01

    Glutamate has been implicated in the central control of mechanisms that maintain body fluid homeostasis. The present studies demonstrate that intracerebroventricular (i.c.v.) injections of the non-N-methyl-d-aspartate (NMDA) receptor antagonists 6, 7-dinitroquinoxaline-2,3-dione (DNQX) and 6-cyano-7-nitroquinoxaline-2,3 dione (CNQX) induce drinking in rats. The dipsogenic effect of i.c.v. DNQX was antagonized by the non-NMDA receptor agonist alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA). The water intake induced by DNQX was also blocked by pretreatment with a NMDA receptor antagonist, MK-801, but not by angiotensin type 1 (AT1) or acetylcholine muscarinic receptor antagonists (losartan and atropine). The results indicate that non-NMDA receptors may exert a tonic inhibitory effect within brain circuits that control dipsogenic activity and that functional integrity of NMDA receptors may be required for the non-NMDA receptor antagonists to induce water intake. Copyright 1998 Published by Elsevier Science B.V.

  4. Pharmacological characterization of NMDA-like receptors in the single-celled organism Paramecium primaurelia.

    PubMed

    Ramoino, Paola; Candiani, Simona; Pittaluga, Anna Maria; Usai, Cesare; Gallus, Lorenzo; Ferrando, Sara; Milanese, Marco; Faimali, Marco; Bonanno, Giambattista

    2014-02-01

    Paramecium primaurelia is a unicellular eukaryote that moves in freshwater by ciliary beating and responds to environmental stimuli by altering motile behaviour. The movements of the cilia are controlled by the electrical changes of the cell membrane: when the intraciliary Ca(2+) concentration associated with plasma membrane depolarization increases, the ciliary beating reverses its direction, and consequently the swimming direction changes. The ciliary reversal duration is correlated with the amount of Ca(2+) influx. Here, we evaluated the effects due to the activation or blockade of N-methyl-d-aspartic acid (NMDA) receptors on swimming behaviour in Paramecium. Paramecia normally swim forward, drawing almost linear tracks. We observed that the simultaneous administration of NMDA and glycine induced a partial ciliary reversal (PaCR) leading to a continuous spiral-like swim. Furthermore, the duration of continuous ciliary reversal (CCR), triggered by high external KCl concentrations, was longer in NMDA+glycine-treated cells. NMDA action required the presence of Ca(2+), as the normal forward swimming was restored when the ion was omitted from the extracellular milieu. The PaCR and the enhancement of CCR duration significantly decreased when the antagonists of the glutamate site D-AP5 or CGS19755, the NMDA channel blocker MK-801 or the glycine site antagonist DCKA was added. The action of NMDA+glycine was also abolished by Zn(2+) or ifenprodil, the GluN2A and the GluN2B NMDA-containing subunit blockers, respectively. Searches of the Paramecium genome database currently available indicate that the NMDA-like receptor with ligand-binding characteristics of an NMDA receptor-like complex, purified from rat brain synaptic membranes and found in some metazoan genomes, is also present in Paramecium. These results provide evidence that functional NMDA receptors similar to those typical of mammalian neuronal cells are present in the single-celled organism Paramecium and thus

  5. Anti-NMDA-receptor antibody encephalitis in infants

    PubMed Central

    Matoq, Amr A.; Rappoport, Adam S.; Yang, Yiting; O'Babatunde, Jessica; Bakerywala, Rubina; Sheth, Raj D.

    2015-01-01

    Purpose Anti-N-methyl-d-aspartate (NMDA) receptor antibody encephalitis is an autoimmune disorder manifesting subacutely with prominent aberrant movements and psychiatric symptoms. The clinical course is one of progressive clinical deterioration that can be halted and often reversed by early diagnosis and treatment. Patterns of presentation and etiology of anti-NMDA-receptor antibody encephalitis are dependent on age and can be challenging to recognize in very young children. Reports Sequential clinical case observations of anti-NMDA-receptor antibody encephalitis presenting in very young children were examined over a year at a single tertiary pediatric institution. Cerebrospinal fluid confirmed anti-NMDA-receptor antibodies in two cases (a 21-month-old boy and a 29-month-old girl) that demonstrated either bizarre behavioral patterns or status epilepticus both associated with progressive deterioration. Once recognized, the clinical course was arrested and reversed by aggressive treatment with plasma exchange, immunoglobulin, and high dose IV steroids. Conclusion Infants with anti-NMDA-receptor antibody encephalitis can present with frank seizures or seizure mimics. Regardless, prompt recognition and aggressive treatment of anti-NMDA-receptor antibody encephalitis, while challenging, can quickly arrest deterioration and hasten recovery, thereby, limiting neurological morbidity. PMID:26744696

  6. Overexpression of α-synuclein simultaneously increases glutamate NMDA receptor phosphorylation and reduces glucocerebrosidase activity.

    PubMed

    Yang, Junfeng; Hertz, Ellen; Zhang, Xiaoqun; Leinartaité, Lina; Lundius, Ebba Gregorsson; Li, Jie; Svenningsson, Per

    2016-01-12

    Progressive accumulation of α-synuclein (α-syn)-containing protein aggregates throughout the nervous system is a pathological hallmark of Parkinson's disease (PD). The mechanisms whereby α-syn exerts neurodegeneration remain to be fully understood. Here we show that overexpression of α-syn in transgenic mice leads to increased phosphorylation of glutamate NMDA receptor (NMDAR) subunits NR1 and NR2B in substantia nigra and striatum as well as reduced glucocerebrosidase (GCase) levels. Similarly, molecular studies performed in mouse N2A cells stably overexpressing human α-syn ((α-syn)N2A) showed that phosphorylation states of the same NMDAR subunits were increased, whereas GCase levels and lysosomal GCase activity were reduced. (α-syn)N2A cells showed an increased sensitivity to neurotoxicity towards 6-hydroxydopamine and NMDA. However, wildtype N2A, but not (α-syn)N2A cells, showed a further reduction in viability when co-incubated with 6-hydroxydopamine and the lysosomal inhibitors NH4Cl and leupeptin, suggesting that α-syn per se perturbs lysosomal functions. NMDA treatment reduced lysosomal GCase activity to the same extent in (α-syn)N2A cells as in wildtype N2A cells, indicating that the α-syn-dependent difference in NMDA neurotoxicity is unrelated to an altered GCase activity. Nevertheless, these data provide molecular evidence that overexpression of α-syn simultaneously induces two potential neurotoxic hits by increasing glutamate NMDA receptor phosphorylation, consistent with increased NMDA receptors functionality, and reducing GCase activity. PMID:26610904

  7. Dendritic NMDA receptors activate axonal calcium channels

    PubMed Central

    Christie, Jason M.; Jahr, Craig E.

    2008-01-01

    Summary NMDA receptor (NMDAR) activation can alter synaptic strength by regulating transmitter release from a variety of neurons in the CNS. As NMDARs are permeable to Ca2+ and monovalent cations, they could alter release directly by increasing presynaptic Ca2+ or indirectly by axonal depolarization sufficient to activate voltage-sensitive Ca2+ channels (VSCCs). Using two-photon microscopy to measure Ca2+ excursions, we found that somatic depolarization or focal activation of dendritic NMDARs elicited small Ca2+ transients in axon varicosities of cerebellar stellate cell interneurons. These axonal transients resulted from Ca2+ entry through VSCCs that were opened by the electrotonic spread of the NMDAR-mediated depolarization elicited in the dendrites. In contrast, we were unable to detect direct activation of NMDARs on axons indicating an exclusive somatodendritic expression of functional NMDARs. In cerebellar stellate cells, dendritic NMDAR activation masquerades as a presynaptic phenomenon and may influence Ca2+-dependent forms of presynaptic plasticity and release. PMID:18957221

  8. Scribble1/AP2 complex coordinates NMDA receptor endocytic recycling.

    PubMed

    Piguel, Nicolas H; Fievre, Sabine; Blanc, Jean-Michel; Carta, Mario; Moreau, Maïté M; Moutin, Enora; Pinheiro, Vera L; Medina, Chantal; Ezan, Jerome; Lasvaux, Léa; Loll, François; Durand, Christelle M; Chang, Kai; Petralia, Ronald S; Wenthold, Robert J; Stephenson, F Anne; Vuillard, Laurent; Darbon, Hervé; Perroy, Julie; Mulle, Christophe; Montcouquiol, Mireille; Racca, Claudia; Sans, Nathalie

    2014-10-23

    The appropriate trafficking of glutamate receptors to synapses is crucial for basic synaptic function and synaptic plasticity. It is now accepted that NMDA receptors (NMDARs) internalize and are recycled at the plasma membrane but also exchange between synaptic and extrasynaptic pools; these NMDAR properties are also key to governing synaptic plasticity. Scribble1 is a large PDZ protein required for synaptogenesis and synaptic plasticity. Herein, we show that the level of Scribble1 is regulated in an activity-dependent manner and that Scribble1 controls the number of NMDARs at the plasma membrane. Notably, Scribble1 prevents GluN2A subunits from undergoing lysosomal trafficking and degradation by increasing their recycling to the plasma membrane following NMDAR activation. Finally, we show that a specific YxxR motif on Scribble1 controls these mechanisms through a direct interaction with AP2. Altogether, our findings define a molecular mechanism to control the levels of synaptic NMDARs via Scribble1 complex signaling. PMID:25310985

  9. Olfactory Bulb Glomerular NMDA Receptors Mediate Olfactory Nerve Potentiation and Odor Preference Learning in the Neonate Rat

    PubMed Central

    Harley, Carolyn W.; Yuan, Qi

    2012-01-01

    Rat pup odor preference learning follows pairing of bulbar beta-adrenoceptor activation with olfactory input. We hypothesize that NMDA receptor (NMDAR)-mediated olfactory input to mitral cells is enhanced during training, such that increased calcium facilitates and shapes the critical cAMP pattern. Here, we demonstrate, in vitro, that olfactory nerve stimulation, at sniffing frequencies, paired with beta-adrenoceptor activation, potentiates olfactory nerve-evoked mitral cell firing. This potentiation is blocked by a NMDAR antagonist and by increased inhibition. Glomerular dishinhibtion also induces NMDAR-sensitive potentiation. In vivo, in parallel, behavioral learning is prevented by glomerular infusion of an NMDAR antagonist or a GABAA receptor agonist. A glomerular GABAA receptor antagonist paired with odor can induce NMDAR-dependent learning. The NMDA GluN1 subunit is phosphorylated in odor-specific glomeruli within 5 min of training suggesting early activation, and enhanced calcium entry, during acquisition. The GluN1 subunit is down-regulated 3 h after learning; and at 24 h post-training the GluN2B subunit is down-regulated. These events may assist memory stability. Ex vivo experiments using bulbs from trained rat pups reveal an increase in the AMPA/NMDA EPSC ratio post-training, consistent with an increase in AMPA receptor insertion and/or the decrease in NMDAR subunits. These results support a model of a cAMP/NMDA interaction in generating rat pup odor preference learning. PMID:22496886

  10. Chronic hyperammonemia induces tonic activation of NMDA receptors in cerebellum.

    PubMed

    ElMlili, Nisrin; Boix, Jordi; Ahabrach, Hanan; Rodrigo, Regina; Errami, Mohammed; Felipo, Vicente

    2010-02-01

    Reduced function of the glutamate--nitric oxide (NO)--cGMP pathway is responsible for some cognitive alterations in rats with hyperammonemia and hepatic encephalopathy. Hyperammonemia impairs the pathway in cerebellum by increasing neuronal nitric oxide synthase (nNOS) phosphorylation in Ser847 by calcium-calmodulin-dependent protein kinase II (CaMKII), reducing nNOS activity, and by reducing nNOS amount in synaptic membranes, which reduces its activation following NMDA receptors activation. The reason for increased CaMKII activity in hyperammonemia remains unknown. We hypothesized that it would be as a result of increased tonic activation of NMDA receptors. The aims of this work were to assess: (i) whether tonic NMDA activation receptors is increased in cerebellum in chronic hyperammonemia in vivo; and (ii) whether this tonic activation is responsible for increased CaMKII activity and reduced activity of nNOS and of the glutamate--NO--cGMP pathway. Blocking NMDA receptors with MK-801 increases cGMP and NO metabolites in cerebellum in vivo and in slices from hyperammonemic rats. This is because of reduced phosphorylation and activity of CaMKII, leading to normalization of nNOS phosphorylation and activity. MK-801 also increases nNOS in synaptic membranes and reduces it in cytosol. This indicates that hyperammonemia increases tonic activation of NMDA receptors leading to reduced activity of nNOS and of the glutamate--NO--cGMP pathway. PMID:20002515

  11. Access of inhibitory neurosteroids to the NMDA receptor

    PubMed Central

    Borovska, Jirina; Vyklicky, Vojtech; Stastna, Eva; Kapras, Vojtech; Slavikova, Barbora; Horak, Martin; Chodounska, Hana; Vyklicky Jr, Ladislav

    2012-01-01

    BACKGROUND AND PURPOSE NMDA receptors are glutamatergic ionotropic receptors involved in excitatory neurotransmission, synaptic plasticity and excitotoxic cell death. Many allosteric modulators can influence the activity of these receptors positively or negatively, with behavioural consequences. 20-Oxo-5β-pregnan-3α-yl sulphate (pregnanolone sulphate; PA-6) is an endogenous neurosteroid that inhibits NMDA receptors and is neuroprotective. We tested the hypothesis that the interaction of PA-6 with the plasma membrane is critical for its inhibitory effect at NMDA receptors. EXPERIMENTAL APPROACH Electrophysiological recordings and live microscopy were performed on heterologous HEK293 cells expressing GluN1/GluN2B receptors and cultured rat hippocampal neurons. KEY RESULTS Our experiments showed that the kinetics of the steroid inhibition were slow and not typical of drug-receptor interaction in an aqueous solution. In addition, the recovery from steroid inhibition was accelerated by β- and γ-cyclodextrin. Values of IC50 assessed for novel synthetic C3 analogues of PA-6 differed by more than 30-fold and were positively correlated with the lipophilicity of the PA-6 analogues. Finally, the onset of inhibition induced by C3 analogues of PA-6 ranged from use-dependent to use-independent. The onset and offset of cell staining by fluorescent analogues of PA-6 were slower than those of steroid-induced inhibition of current responses mediated by NMDA receptors. CONCLUSION AND IMPLICATIONS We conclude that steroid accumulation in the plasma membrane is the route by which it accesses a binding site on the NMDA receptor. Thus, our results provide a possible structural framework for pharmacologically targeting the transmembrane domains of the receptor. PMID:22188257

  12. Subtype selective NMDA receptor antagonists induce recovery of synapses lost following exposure to HIV-1 Tat

    PubMed Central

    Shin, AH; Kim, HJ; Thayer, SA

    2012-01-01

    BACKGROUND AND PURPOSE Neurocognitive disorders afflict approximately 20% of HIV-infected patients. HIV-1-infected cells in the brain shed viral proteins such as transactivator of transcription (Tat). Tat elicits cell death and synapse loss via processes initiated by NMDA receptor activation but mediated by separate downstream signalling pathways. Subunit selective NMDA receptor antagonists may differentially modulate survival relative to synaptic changes. EXPERIMENTAL APPROACH Tat-evoked cell death was quantified by measuring propidium iodide uptake into rat hippocampal neurons in culture. The effects of Tat on synaptic changes were measured using an imaging-based assay that quantified clusters of the scaffolding protein postsynaptic density 95 fused to green fluorescent protein. KEY RESULTS Dizocilpine, a non-competitive NMDA receptor antagonist, inhibited Tat-induced synapse loss, subsequent synapse recovery and Tat-induced cell death with comparable potencies. Memantine (10 µM) and ifenprodil (10 µM), which preferentially inhibit GluN2B-containing NMDA receptors, protected from Tat-induced cell death with no effect on synapse loss. Surprisingly, memantine and ifenprodil induced synapse recovery in the presence of Tat. In contrast, the GluN2A-prefering antagonist TCN201 prevented synapse loss and recovery with no effect on cell death. CONCLUSIONS AND IMPLICATIONS Synapse loss is a protective mechanism that enables the cell to cope with excess excitatory input. Thus, memantine and ifenprodil are promising neuroprotective drugs because they spare synaptic changes and promote survival. These GluN2B-preferring drugs induced recovery from Tat-evoked synapse loss, suggesting that synaptic pharmacology changed during the neurotoxic process. NMDA receptor subtypes differentially participate in the adaptation and death induced by excitotoxic insult. PMID:22142193

  13. Basal Levels of AMPA Receptor GluA1 Subunit Phosphorylation at Threonine 840 and Serine 845 in Hippocampal Neurons

    ERIC Educational Resources Information Center

    Babiec, Walter E.; Guglietta, Ryan; O'Dell, Thomas J.

    2016-01-01

    Dephosphorylation of AMPA receptor (AMPAR) GluA1 subunits at two sites, serine 845 (S845) and threonine 840 (T840), is thought to be involved in NMDA receptor-dependent forms of long-term depression (LTD). Importantly, the notion that dephosphorylation of these sites contributes to LTD assumes that a significant fraction of GluA1 subunits are…

  14. EVALUATING THE NMDA-GLUTAMATE RECEPTOR AS A SITE OF ACTION FOR TOLUENE, IN VIVO

    EPA Science Inventory

    In vitro, toluene disrupts the function of NMDA-glutamate receptors, indicating that effects on NMDA receptor function may contribute to toluene neurotoxicity. NMDA-glutamate receptors are widely present in the visual system and contribute to pattern-elicited visual evoked potent...

  15. Amygdala Infusions of an NR2B-Selective or an NR2A-Preferring NMDA Receptor Antagonist Differentially Influence Fear Conditioning and Expression in the Fear-Potentiated Startle Test

    ERIC Educational Resources Information Center

    Walker, David L.; Davis, Michael

    2008-01-01

    Within the amygdala, most N-methyl-D-aspartic acid (NMDA) receptors consist of NR1 subunits in combination with either NR2A or NR2B subunits. Because the particular subunit composition greatly influences the receptors' properties, we investigated the contribution of both subtypes to fear conditioning and expression. To do so, we infused the…

  16. Receptor mechanisms and circuitry underlying NMDA antagonist neurotoxicity.

    PubMed

    Farber, N B; Kim, S H; Dikranian, K; Jiang, X P; Heinkel, C

    2002-01-01

    NMDA glutamate receptor antagonists are used in clinical anesthesia, and are being developed as therapeutic agents for preventing neurodegeneration in stroke, epilepsy, and brain trauma. However, the ability of these agents to produce neurotoxicity in adult rats and psychosis in adult humans compromises their clinical usefulness. In addition, an NMDA receptor hypofunction (NRHypo) state might play a role in neurodegenerative and psychotic disorders, like Alzheimer's disease and schizophrenia. Thus, understanding the mechanism underlying NRHypo-induced neurotoxicity and psychosis could have significant clinically relevant benefits. NRHypo neurotoxicity can be prevented by several classes of agents (e.g. antimuscarinics, non-NMDA glutamate antagonists, and alpha(2) adrenergic agonists) suggesting that the mechanism of neurotoxicity is complex. In the present study a series of experiments was undertaken to more definitively define the receptors and complex neural circuitry underlying NRHypo neurotoxicity. Injection of either the muscarinic antagonist scopolamine or the non-NMDA antagonist NBQX directly into the cortex prevented NRHypo neurotoxicity. Clonidine, an alpha(2) adrenergic agonist, protected against the neurotoxicity when injected into the basal forebrain. The combined injection of muscarinic and non-NMDA Glu agonists reproduced the neurotoxic reaction. Based on these and other results, we conclude that the mechanism is indirect, and involves a complex network disturbance, whereby blockade of NMDA receptors on inhibitory neurons in multiple subcortical brain regions, disinhibits glutamatergic and cholinergic projections to the cerebral cortex. Simultaneous excitotoxic stimulation of muscarinic (m(3)) and glutamate (AMPA/kainate) receptors on cerebrocortical neurons appears to be the proximal mechanism by which the neurotoxic and psychotomimetic effects of NRHypo are mediated. PMID:11803444

  17. Pregnenolone sulfate and its enantiomer: differential modulation of memory in a spatial discrimination task using forebrain NMDA receptor deficient mice

    PubMed Central

    Petit, Géraldine H.; Tobin, Christine; Krishnan, Kathiresan; Moricard, Yves; Covey, Douglas F.; Rondi-Reig, Laure; Akwa, Yvette

    2010-01-01

    This study examined the role of forebrain N-methyl-D-aspartate receptors (NMDA-Rs) in the promnesiant effects of natural (+) pregnenolone sulfate (PREGS) and its synthetic (−) enantiomer ent-PREGS in young adult mice. Using the two-trial arm discrimination task in a Y-maze, PREGS and ent-PREGS administration to control mice increased memory performances. In mice with a knock-out of the NR1 subunit of NMDA-Rs in the forebrain, the promnesiant effect of ent-PREGS was maintained whereas the activity of PREGS was lost. Memory enhancement by PREGS involves the NMDA-R activity in the hippocampal CA1 area and possibly in some locations of the cortical layers, whereas ent-PREGS acts independently of NMDA-R function. PMID:21036556

  18. Molecular interactions of the type 1 human immunodeficiency virus transregulatory protein Tat with N-methyl-d-aspartate receptor subunits.

    PubMed

    Chandra, T; Maier, W; König, H-G; Hirzel, K; Kögel, D; Schüler, T; Chandra, A; Demirhan, I; Laube, B

    2005-01-01

    We investigated the effect of type 1 human immunodeficiency virus (HIV-1) regulatory protein Tat on N-methyl-d-aspartate (NMDA) receptors expressed in Xenopus oocytes by voltage-clamp recording and its role in NMDA-mediated neurotoxicity using cultured rat hippocampal neurons. Tat (0.01-1muM) potentiated NMDA-induced currents of recombinant NMDA receptors. However, in the presence of Zn(2+), the potentiating effect of Tat was much more pronounced, indicating an additional Zn(2+)-related effect on NMDA receptors. Consistently, Tat potentiated currents of the particularly Zn(2+)-sensitive NR1/NR2A NMDA receptor with a higher efficacy, whereas currents from a Zn(2+)-insensitive mutant were only marginally augmented. In addition, chemical-modified Tat, deficient for metal binding, did not reverse Zn(2+)-mediated inhibition of NMDA responses, demonstrating that Tat disinhibits NMDA receptors from Zn(2+)-mediated antagonism by complexing the cation. We therefore investigated the interplay of Tat and Zn(2+) in NMDA-mediated neurotoxicity using cultures of rat hippocampal neurons. Zn(2+) exhibited a prominent rescuing effect when added together with the excitotoxicant NMDA, which could be reverted by the Zn(2+)-chelator tricine. Similar to tricine, Tat enhanced NMDA-mediated neurotoxicity in the presence of neuroprotective Zn(2+) concentrations. Double-staining with antibodies against Tat and the NR1 subunit of the NMDA receptor revealed partial colocalization of the immunoreactivities in membrane patches of hippocampal neurons, supporting the idea of a direct interplay between Tat and glutamatergic transmission. We therefore propose that release of Zn(2+)-mediated inhibition of NMDA receptors by HIV-1 Tat contributes to the neurotoxic effect of glutamate and may participate in the pathogenesis of AIDS-associated dementia. PMID:15964699

  19. FROM MOLECULAR PHYLOGENY TOWARDS DIFFERENTIATING PHARMACOLOGY FOR NMDA RECEPTOR SUBTYPES

    PubMed Central

    Platt, Randall J.; Curtice, Kigen J.; Twede, Vernon D.; Watkins, Maren; Gruszczyński, Paweł; Bulaj, Grzegorz; Horvath, Martin P.; Olivera, Baldomero M.

    2014-01-01

    In order to decode the roles that N-methyl-D-aspartate (NMDA) receptors play in excitatory neurotransmission, synaptic plasticity, and neuropathologies, there is need for ligands that differ in their subtype selectivity. The conantokin family of Conus peptides is the only group of peptidic natural products known to target NMDA receptors. Using a search that was guided by phylogeny, we identified new conantokins from the marine snail Conus bocki that complement the current repertoire of NMDA receptor pharmacology. Channel currents measured in Xenopus oocytes demonstrate conantokins conBk-A, conBk-B, and conBk-C have highest potencies for NR2D containing receptors, in contrast to previously characterized conantokins that preferentially block NR2B containing NMDA receptors. Conantokins are rich in γ-carboxyglutamate, typically 17–34 residues, and adopt helical structure in a calcium-dependent manner. As judged by CD spectroscopy, conBk-C adopts significant helical structure in a calcium ion-dependent manner, while calcium, on its own, appears insufficient to stabilize helical conformations of conBk-A or conBk-B. Molecular dynamics simulations help explain the differences in calcium-stabilized structures. Two-dimensional NMR spectroscopy shows that the 9-residue conBk-B is relatively unstructured but forms a helix in the presence of TFE and calcium ions that is similar to other conantokin structures. These newly discovered conantokins hold promise that further exploration of small peptidic antagonists will lead to a set of pharmacological tools that can be used to characterize the role of NMDA receptors in nervous system function and disease. PMID:24508768

  20. NMDA Receptors on Dopaminoceptive Neurons Are Essential for Drug-Induced Conditioned Place Preference123

    PubMed Central

    Tokarski, Krzysztof; Bobula, Bartosz; Zygmunt, Magdalena; Smutek, Magdalena; Kamińska, Katarzyna; Gołembiowska, Krystyna; Hess, Grzegorz; Przewlocki, Ryszard

    2016-01-01

    Abstract Plasticity of the brain’s dopamine system plays a crucial role in adaptive behavior by regulating appetitive motivation and the control of reinforcement learning. In this study, we investigated drug- and natural-reward conditioned behaviors in a mouse model in which the NMDA receptor-dependent plasticity of dopaminoceptive neurons was disrupted. We generated a transgenic mouse line with inducible selective inactivation of the NR1 subunit in neurons expressing dopamine D1 receptors (the NR1D1CreERT2 mice). Whole-cell recordings of spontaneous EPSCs on neurons in the nucleus accumbens confirmed that a population of neurons lacked the NMDA receptor-dependent component of the current. This effect was accompanied by impaired long-term potentiation in the nucleus accumbens and in the CA1 area of the ventral, but not the dorsal, hippocampus. Mutant mice did not differ from control animals when tested for pavlovian or instrumental conditioning. However, NR1D1CreERT2 mice acquired no preference for a context associated with administration of drugs of abuse. In the conditioned place preference paradigm, mutant mice did not spend more time in the context paired with cocaine, morphine, or ethanol, although these mice acquired a preference for sucrose jelly and an aversion to naloxone injections, as normal. Thus, we observed that the selective inducible ablation of the NMDA receptors specifically blocks drug-associated context memory with no effect on positive reinforcement in general. PMID:27294197

  1. NMDA Receptors on Dopaminoceptive Neurons Are Essential for Drug-Induced Conditioned Place Preference.

    PubMed

    Sikora, Magdalena; Tokarski, Krzysztof; Bobula, Bartosz; Zajdel, Joanna; Jastrzębska, Kamila; Cieślak, Przemysław Eligiusz; Zygmunt, Magdalena; Sowa, Joanna; Smutek, Magdalena; Kamińska, Katarzyna; Gołembiowska, Krystyna; Engblom, David; Hess, Grzegorz; Przewlocki, Ryszard; Rodriguez Parkitna, Jan

    2016-01-01

    Plasticity of the brain's dopamine system plays a crucial role in adaptive behavior by regulating appetitive motivation and the control of reinforcement learning. In this study, we investigated drug- and natural-reward conditioned behaviors in a mouse model in which the NMDA receptor-dependent plasticity of dopaminoceptive neurons was disrupted. We generated a transgenic mouse line with inducible selective inactivation of the NR1 subunit in neurons expressing dopamine D1 receptors (the NR1(D1CreERT2) mice). Whole-cell recordings of spontaneous EPSCs on neurons in the nucleus accumbens confirmed that a population of neurons lacked the NMDA receptor-dependent component of the current. This effect was accompanied by impaired long-term potentiation in the nucleus accumbens and in the CA1 area of the ventral, but not the dorsal, hippocampus. Mutant mice did not differ from control animals when tested for pavlovian or instrumental conditioning. However, NR1(D1CreERT2) mice acquired no preference for a context associated with administration of drugs of abuse. In the conditioned place preference paradigm, mutant mice did not spend more time in the context paired with cocaine, morphine, or ethanol, although these mice acquired a preference for sucrose jelly and an aversion to naloxone injections, as normal. Thus, we observed that the selective inducible ablation of the NMDA receptors specifically blocks drug-associated context memory with no effect on positive reinforcement in general. PMID:27294197

  2. Paradoxical proepileptic response to NMDA receptor blockade linked to cortical interneuron defect in stargazer mice.

    PubMed

    Maheshwari, Atul; Nahm, Walter K; Noebels, Jeffrey L

    2013-01-01

    Paradoxical seizure exacerbation by anti-epileptic medication is a well-known clinical phenomenon in epilepsy, but the cellular mechanisms remain unclear. One possibility is enhanced network disinhibition by unintended suppression of inhibitory interneurons. We investigated this hypothesis in the stargazer mouse model of absence epilepsy, which bears a mutation in stargazin, an AMPA receptor trafficking protein. If AMPA signaling onto inhibitory GABAergic neurons is impaired, their activation by glutamate depends critically upon NMDA receptors. Indeed, we find that stargazer seizures are exacerbated by NMDA receptor blockade with CPP (3-[(R)-2-carboxypiperazin-4-yl]-prop-2-enyl-1-phosphonic acid) and MK-801, whereas other genetic absence epilepsy models are sensitive to these antagonists. To determine how an AMPA receptor trafficking defect could lead to paradoxical network activation, we analyzed stargazin and AMPA receptor localization and found that stargazin is detected exclusively in parvalbumin-positive (PV (+)) fast-spiking interneurons in somatosensory cortex, where it is co-expressed with the AMPA receptor subunit GluA4. PV (+) cortical interneurons in stargazer show a near twofold decrease in the dendrite:soma GluA4 expression ratio compared to wild-type (WT) littermates. We explored the functional consequence of this trafficking defect on network excitability in neocortical slices. Both NMDA receptor antagonists suppressed 0 Mg (2) (+)-induced network discharges in WT but augmented bursting in stargazer cortex. Interneurons mediate this paradoxical response, since the difference between genotypes was masked by GABA receptor blockade. Our findings provide a cellular locus for AMPA receptor-dependent signaling defects in stargazer cortex and define an interneuron-dependent mechanism for paradoxical seizure exacerbation in absence epilepsy. PMID:24065886

  3. Coupling of energy metabolism and synaptic transmission at the transcriptional level: Role of nuclear respiratory factor 1 in regulating both cytochrome c oxidase and NMDA glutamate receptor subunit genes

    PubMed Central

    Dhar, Shilpa S.; Wong-Riley, Margaret T. T.

    2009-01-01

    Neuronal activity and energy metabolism are tightly coupled processes. Regions high in neuronal activity, especially of the glutamatergic type, have high levels of cytochrome c oxidase (COX). Perturbations in neuronal activity affect the expressions of COX and glutamatergic N-methyl-D-aspartate receptor subunit 1 (NR1). The present study sought to test our hypothesis that the coupling extends to the transcriptional level, whereby NR1 and possibly other NR subunits and COX are co-regulated by the same transcription factor, nuclear respiratory factor 1 (NRF-1), which regulates all COX subunit genes. By means of multiple approaches, including in silico analysis, electrophoretic mobility shift and supershift assays, in vivo chromatin immunoprecipitation, promoter mutations, and real-time quantitative PCR, NRF-1 was found to functionally bind to the promoters of Grin 1 (NR1), Grin 2b (NR2b) and COX subunit genes, but not of Grin2a and Grin3a genes. These transcripts were up-regulated by KCl and down-regulated by TTX in cultured primary neurons. However, silencing of NRF-1 with small interference RNA blocked the up-regulation of Grin1, Grin2b, and COX induced by KCl, and over-expression of NRF-1 rescued these transcripts that were suppressed by TTX. NRF-1 binding sites on Grin1 and Grin2b genes are also highly conserved among mice, rats, and humans. Thus, NRF-1 is an essential transcription factor critical in the co-regulation of NR1, NR2b, and COX, and coupling exists at the transcriptional level to ensure coordinated expressions of proteins important for synaptic transmission and energy metabolism. PMID:19144849

  4. Roles of subunit phosphorylation in regulating glutamate receptor function

    PubMed Central

    Wang, John Q.; Guo, Ming-Lei; Jin, Dao-Zhong; Xue, Bing; Fibuch, Eugene E.; Mao, Li-Min

    2014-01-01

    Protein phosphorylation is an important mechanism for regulating ionotropic glutamate receptors (iGluRs). Early studies have established that major iGluR subtypes, including α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptors and N-methyl-D-aspartate (NMDA) receptors, are subject to phosphorylation. Multiple serine, threonine, and tyrosine residues predominantly within the C-terminal regions of AMPA receptor and NMDA receptor subunits have been identified as sensitive phosphorylation sites. These distinct sites undergo either constitutive phosphorylation or activity-dependent phosphorylation induced by changing cellular and synaptic inputs as reversible events. An increasing number of synapse-enriched protein kinases have been found to phosphorylate iGluR. The common kinases include protein kinase A, protein kinase C, Ca2+/calmodulin-dependent protein kinase II, Src/Fyn non-receptor tyrosine kinases, and cyclin dependent kinase-5. Regulated phosphorylation plays a well-documented role in modulating the biochemical, biophysical, and functional properties of the receptor. In the future, identifying the precise mechanisms how phosphorylation regulates iGluR activities and finding the link between iGluR phosphorylation and the pathogenesis of various brain diseases, including psychiatric and neurodegenerative diseases, chronic pain, stroke, Alzheimer’s disease and substance addiction, will be hot topics and could contribute to the development of novel pharmacotherapies, by targeting the defined phosphorylation process, for suppressing iGluR-related disorders. PMID:24291102

  5. Endocytosis and degradative sorting of NMDA receptors by conserved membrane-proximal signals.

    PubMed

    Scott, Derek B; Michailidis, Ioannis; Mu, Yuanyue; Logothetis, Diomedes; Ehlers, Michael D

    2004-08-11

    Regulation of the abundance of NMDA receptors (NMDARs) at excitatory synapses is critical during changes in synaptic efficacy underlying learning and memory as well as during synapse formation throughout neural development. However, the molecular signals that govern NMDAR delivery, maintenance, and internalization remain unclear. In this study, we identify a conserved family of membrane-proximal endocytic signals, two within the NMDAR type 1 (NR1) subunit and one within the NR2A and NR2B subunits, necessary and sufficient to drive the internalization of NMDARs. These endocytic motifs reside in the region of NMDAR subunits immediately after the fourth membrane segment, a region implicated in use-dependent rundown and NMDA channel inactivation. Although endocytosis driven by the distal C-terminal domain of NR2B is followed by rapid recycling, internalization mediated by membrane-proximal motifs selectively targets receptors to late endosomes and accelerates degradation. These results define a novel conserved signature of NMDARs regulating internalization and postendocytic trafficking. PMID:15306643

  6. Altered zinc sensitivity of NMDA receptors harboring clinically-relevant mutations.

    PubMed

    Serraz, Benjamin; Grand, Teddy; Paoletti, Pierre

    2016-10-01

    Recent human genetic studies have identified a surprisingly high number of alterations in genes encoding NMDA receptor (NMDAR) subunits in several common brain diseases. Among NMDAR subunits, the widely-expressed GluN2A subunit appears particularly affected, with tens of de novo or inherited mutations associated with neurodevelopmental conditions including childhood epilepsies and cognitive deficits. Despite the increasing identification of NMDAR mutations of clinical interest, there is still little information about the effects of the mutations on receptor and network function. Here we analyze the impact on receptor expression and function of nine GluN2A missense (i.e. single-point) mutations targeting the N-terminal domain, a large regulatory region involved in subunit assembly and allosteric signaling. While several mutations produced no or little apparent effect on receptor expression, gating and pharmacology, two showed a drastic expression phenotype and two resulted in marked alterations in the sensitivity to zinc, a potent allosteric inhibitor of GluN1/GluN2A receptors and modulator of excitatory synaptic transmission. Surprisingly, both increase (GluN2A-R370W) and decrease (GluN2A-P79R) of zinc sensitivity were observed on receptors containing either one or two copies of the mutated subunits. Overexpression of the mutant subunits in cultured rat neurons confirmed the results from heterologous expression. These results, together with previously published data, indicate that disease-causing mutations in NMDARs produce a wide spectrum of receptor alterations, at least in vitro. They also point to a critical role of the zinc-NMDAR interaction in neuronal function and human health. PMID:27288002

  7. Differential effects of N-acetyl-aspartyl-glutamate on synaptic and extrasynaptic NMDA receptors are subunit- and pH-dependent in the CA1 region of the mouse hippocampus.

    PubMed

    Khacho, Pamela; Wang, Boyang; Ahlskog, Nina; Hristova, Elitza; Bergeron, Richard

    2015-10-01

    Ischemic strokes cause excessive release of glutamate, leading to overactivation of N-methyl-d-aspartate receptors (NMDARs) and excitotoxicity-induced neuronal death. For this reason, inhibition of NMDARs has been a central focus in identifying mechanisms to avert this extensive neuronal damage. N-acetyl-aspartyl-glutamate (NAAG), the most abundant neuropeptide in the brain, is neuroprotective in ischemic conditions in vivo. Despite this evidence, the exact mechanism underlying its neuroprotection, and more specifically its effect on NMDARs, is currently unknown due to conflicting results in the literature. Here, we uncover a pH-dependent subunit-specific action of NAAG on NMDARs. Using whole-cell electrophysiological recordings on acute hippocampal slices from adult mice and on HEK293 cells, we found that NAAG increases synaptic GluN2A-containing NMDAR EPSCs, while effectively decreasing extrasynaptic GluN2B-containing NMDAR EPSCs in physiological pH. Intriguingly, the results of our study further show that in low pH, which is a physiological occurrence during ischemia, NAAG depresses GluN2A-containing NMDAR EPSCs and amplifies its inhibitory effect on GluN2B-containing NMDAR EPSCs, as well as upregulates the surface expression of the GluN2A subunit. Altogether, our data demonstrate that NAAG has differential effects on NMDAR function based on subunit composition and pH. These findings suggest that the role of NAAG as a neuroprotective agent during an ischemic stroke is likely mediated by its ability to reduce NMDAR excitation. The inhibitory effect of NAAG on NMDARs and its enhanced function in acidic conditions make NAAG a prime therapeutic agent for the treatment of ischemic events. PMID:26303888

  8. Phosphorylation of Tyrosine 1070 at the GluN2B Subunit Is Regulated by Synaptic Activity and Critical for Surface Expression of N-Methyl-D-aspartate (NMDA) Receptors.

    PubMed

    Lu, Wen; Fang, Weiqing; Li, Jian; Zhang, Bin; Yang, Qian; Yan, Xunyi; Peng, Lin; Ai, Heng; Wang, Jie-jie; Liu, Xiao; Luo, Jianhong; Yang, Wei

    2015-09-18

    The number and subunit composition of synaptic N-methyl-d-aspartate receptors (NMDARs) play critical roles in synaptic plasticity, learning, and memory and are implicated in neurological disorders. Tyrosine phosphorylation provides a powerful means of regulating NMDAR function, but the underling mechanism remains elusive. In this study we identified a tyrosine site on the GluN2B subunit, Tyr-1070, which was phosphorylated by a proto-oncogene tyrosine-protein (Fyn) kinase and critical for the surface expression of GluN2B-containing NMDARs. The phosphorylation of GluN2B at Tyr-1070 was required for binding of Fyn kinase to GluN2B, which up-regulated the phosphorylation of GluN2B at Tyr-1472. Moreover, our results revealed that the phosphorylation change of GluN2B at Tyr-1070 accompanied the Tyr-1472 phosphorylation and Fyn associated with GluN2B in synaptic plasticity induced by both chemical and contextual fear learning. Taken together, our findings provide a new mechanism for regulating the surface expression of NMDARs with implications for synaptic plasticity. PMID:26229100

  9. Presynaptic NMDA receptors – dynamics and distribution in developing axons in vitro and in vivo

    PubMed Central

    Gill, Ishwar; Droubi, Sammy; Giovedi, Silvia; Fedder, Karlie N.; Bury, Luke A. D.; Bosco, Federica; Sceniak, Michael P.; Benfenati, Fabio; Sabo, Shasta L.

    2015-01-01

    ABSTRACT During cortical development, N-methyl-D-aspartate (NMDA) receptors (NMDARs) facilitate presynaptic terminal formation, enhance neurotransmitter release and are required in presynaptic neurons for spike-timing-dependent long-term depression (tLTD). However, the extent to which NMDARs are found within cortical presynaptic terminals has remained controversial, and the sub-synaptic localization and dynamics of axonal NMDARs are unknown. Here, using live confocal imaging and biochemical purification of presynaptic membranes, we provide strong evidence that NMDARs localize to presynaptic terminals in vitro and in vivo in a developmentally regulated manner. The NR1 and NR2B subunits (also known as GRIN1 and GRIN2B, respectively) were found within the active zone membrane, where they could respond to synaptic glutamate release. Surprisingly, NR1 also appeared in glutamatergic and GABAergic synaptic vesicles. During synaptogenesis, NR1 was mobile throughout axons – including growth cones and filopodia, structures that are involved in synaptogenesis. Upon synaptogenic contact, NMDA receptors were quickly recruited to terminals by neuroligin-1 signaling. Unlike dendrites, the trafficking and distribution of axonal NR1 were insensitive to activity changes, including NMDA exposure, local glutamate uncaging or action potential blockade. These results support the idea that presynaptic NMDARs play an early role in presynaptic development. PMID:25526735

  10. Synapses, NMDA receptor activity and neuronal Aβ production in Alzheimer's disease.

    PubMed

    Bordji, Karim; Becerril-Ortega, Javier; Buisson, Alain

    2011-01-01

    A direct relationship has been established between synaptic activity and amyloid-β secretion. Dysregulation of neuronal calcium homeostasis was shown to increase production of amyloid-β, contributing to the initiation of Alzheimer's disease. Among the different routes of Ca(2+) entry, N-methyl-d-aspartate (NMDA) receptors, a subtype of ionotropic glutamate receptors, are especially involved in this process because of their ability to gate high levels of Ca(2+) influx. These receptors have been extensively studied for their crucial roles in synaptic plasticity that underlies learning and memory but also in neurotoxicity occurring during acute brain injuries and neurodegenerative diseases. For one decade, several studies provided evidence that NMDA receptor activation could have distinct consequences on neuronal fate, depending on their location. Synaptic NMDA receptor activation is neuroprotective, whereas extrasynaptic NMDA receptors trigger neuronal death and/or neurodegenerative processes. Recent data suggest that chronic activation of extrasynaptic NMDA receptors leads to a sustained neuronal amyloid-β release and could be involved in the pathogenesis of Alzheimer's disease. Thus, as for other neurological diseases, therapeutic targeting of extrasynaptic NMDA receptors could be a promising strategy. Following this concept, memantine, unlike other NMDA receptor antagonists was shown, to preferentially target the extrasynaptic NMDA receptor signaling pathways, while relatively sparing normal synaptic activity. This molecular mechanism could therefore explain why memantine is, to date, the only clinically approved NMDA receptor antagonist for the treatment of dementia. PMID:21568789

  11. Changes in NMDA receptor-induced cyclic nucleotide synthesis regulate the age-dependent increase in PDE4A expression in primary cortical cultures

    PubMed Central

    Hajjhussein, Hassan; Suvarna, Neesha U.; Gremillion, Carmen; Judson Chandler, L.; O’Donnell, James M.

    2007-01-01

    NMDA receptor-induced cAMP and cGMP are selectively hydrolyzed by PDE4 and PDE2, respectively, in rat primary cerebral cortical and hippocampal cultures. Because cAMP levels regulate the expression of PDE4 in rat primary cortical cultures, we examined the manner in which NMDA receptor activity regulates the age-dependent increase in the expression of PDE4A observed in vivo and in vitro. Inhibiting the activity of NR2B subunit with ifenprodil blocked NMDA receptor-induced cGMP synthesis and increased NMDA receptor-induced cAMP levels in a manner that reduced PDE4 activity. Therefore, NR1/NR2B receptor-induced cGMP signaling is involved in an acute cross-talk regulation of NR1/NR2A receptor-induced cAMP levels, mediated by PDE4. Chronic inhibition of NMDA receptor activity with MK-801 reduced PDE4A1 and PDE4A5 expression and activity in a time-dependent manner; this effect was reversed by adding the PKA activator dbr-cAMP. Inhibiting GABA receptors with bicuculline increased NMDA receptor-induced cAMP synthesis and PDE4A expression in cultures treated between DIV 16 and DIV 21 but not in cultures treated between DIV 8 and DIV 13. This effect was due to a high tone of NMDA receptor-induced cGMP in younger cultures, which negatively regulated the expression of PDE4A by a PKG-mediated process. The present results are consistent with behavioral data showing that both PDE4 and PDE2 are involved in NMDA receptor-mediated memory processes. PMID:17407767

  12. The selectivity of conantokin-G for ion channel inhibition of NR2B subunit-containing NMDA receptors is regulated by amino acid residues in the S2 region of NR2B.

    PubMed

    Sheng, Zhenyu; Liang, Zhong; Geiger, James H; Prorok, Mary; Castellino, Francis J

    2009-08-01

    The conantokins are short, naturally occurring peptides that inhibit ion flow through N-methyl-d-aspartate receptor (NMDAR) channels. One member of this peptide family, conantokin-G (con-G), shows high selectivity for antagonism of NR2B-containing NMDAR channels, whereas other known conantokins are less selective inhibitors with regard to the nature of the NR2 subunit of the NMDAR complex. In order to define the molecular determinants of NR2B that govern con-G selectivity, we evaluated the ability of con-G to inhibit NMDAR ion channels expressed in human embryonic kidney (HEK)293 cells transfected with NR1, in combination with various NR2A/2B chimeras and point mutants, by electrophysiology using cells voltage-clamped in the whole-cell configuration. We found that a variant of the con-G-insensitive subunit, NR2A, in which the 158 residues comprising the S2 peptide segment (E(657)-I(814)) were replaced by the corresponding S2 region of NR2B (E(658)-I(815)), results in receptors that are highly sensitive to inhibition by con-G. Of the 22 amino acids that are different between the NR2A-S2 and the NR2B-S2 regions, exchange of one of these, M(739) of NR2B for the equivalent K(738) of NR2A, was sufficient to completely import the inhibitory activity of con-G into NR1b/NR2A-containing NMDARs. Some reinforcement of this effect was found by substitution of a second amino acid, K(755) of NR2B for Y(754) of NR2A. The discovery of the molecular determinants of NR2B selectivity with con-G has implications for the design of subunit-selective neurobiological probes and drug therapies, in addition to advancing our understanding of NR2B- versus NR2A-mediated neurological processes. PMID:19427876

  13. PSD-95 and PKC converge in regulating NMDA receptor trafficking and gating

    PubMed Central

    Lin, Ying; Jover-Mengual, Teresa; Wong, Judy; Bennett, Michael V. L.; Zukin, R. Suzanne

    2006-01-01

    Neuronal NMDA receptors (NMDARs) colocalize with postsynaptic density protein-95 (PSD-95), a putative NMDAR anchoring protein and core component of the PSD, at excitatory synapses. PKC activation and PSD-95 expression each enhance NMDAR channel opening rate and number of functional channels at the cell surface. Here we show in Xenopus oocytes that PSD-95 and PKC potentiate NMDA gating and trafficking in a nonadditive manner. PSD-95 and PKC each enhance NMDA channel activity, with no change in single-channel conductance, reversal potential or mean open time. PSD-95 and PKC each potentiate NMDA channel opening rate (kβ) and number of functional channels at the cell surface (N), as indicated by more rapid current decay and enhanced charge transfer in the presence of the open channel blocker MK-801. PSD-95 and PKC each increase NMDAR surface expression, as indicated by immunofluorescence. PKC potentiates NMDA channel function and NMDAR surface expression to the same final absolute values in the absence or presence of PSD-95. Thus, PSD-95 partially occludes PKC potentiation. We further show that Ser-1462, a putative phosphorylation target within the PDZ-binding motif of the NR2A subunit, is required for PSD-95-induced potentiation and partial occlusion of PKC potentiation. Coimmunoprecipitation experiments with cortical neurons in culture indicate that PKC activation promotes assembly of NR2 with NR1, and that the newly assembled NMDARs are not associated with PSD-95. These findings predict that synaptic scaffolding proteins and protein kinases convergently modulate NMDAR gating and trafficking at synaptic sites. PMID:17179037

  14. Catatonic Syndrome in Anti-NMDA Receptor Encephalitis.

    PubMed

    Mythri, Starlin Vijay; Mathew, Vivek

    2016-01-01

    Anti-N-methyl-D-aspartate (NMDA) receptor encephalitis is a newly recognised autoimmune condition. With its typical clinical pattern, consistent association with the presence of auto antibodies and rapid improvement with immunotherapy, this condition is giving insights into the boundaries between psychiatry and other neurosciences, and is opening avenues for future research. In a young lady who presented with catatonia, we considered anti-NMDA receptor encephalitis, after ruling out other aetiologies. After a positive antibody test we treated her with immunotherapy. She showed gradual improvement in her psychotic and catatonic symptoms. Knowledge regarding the nature and function of NMDA receptors and pathophysiology of this particular encephalitis is important for psychiatric practice. The great opportunity for research in this area due to its association with psychotic disorders is evident but an appeal to temper the enthusiasm by considering the historical lessons learnt from Karl Jaspers' critique of General Paresis of Insane, is in place. Catatonic syndrome has to be conceptualised broadly and should be recognised with a separate nosological position. PMID:27114630

  15. Catatonic Syndrome in Anti-NMDA Receptor Encephalitis

    PubMed Central

    Mythri, Starlin Vijay; Mathew, Vivek

    2016-01-01

    Anti-N-methyl-D-aspartate (NMDA) receptor encephalitis is a newly recognised autoimmune condition. With its typical clinical pattern, consistent association with the presence of auto antibodies and rapid improvement with immunotherapy, this condition is giving insights into the boundaries between psychiatry and other neurosciences, and is opening avenues for future research. In a young lady who presented with catatonia, we considered anti-NMDA receptor encephalitis, after ruling out other aetiologies. After a positive antibody test we treated her with immunotherapy. She showed gradual improvement in her psychotic and catatonic symptoms. Knowledge regarding the nature and function of NMDA receptors and pathophysiology of this particular encephalitis is important for psychiatric practice. The great opportunity for research in this area due to its association with psychotic disorders is evident but an appeal to temper the enthusiasm by considering the historical lessons learnt from Karl Jaspers’ critique of General Paresis of Insane, is in place. Catatonic syndrome has to be conceptualised broadly and should be recognised with a separate nosological position. PMID:27114630

  16. NMDA receptor antagonist ketamine impairs feature integration in visual perception.

    PubMed

    Meuwese, Julia D I; van Loon, Anouk M; Scholte, H Steven; Lirk, Philipp B; Vulink, Nienke C C; Hollmann, Markus W; Lamme, Victor A F

    2013-01-01

    Recurrent interactions between neurons in the visual cortex are crucial for the integration of image elements into coherent objects, such as in figure-ground segregation of textured images. Blocking N-methyl-D-aspartate (NMDA) receptors in monkeys can abolish neural signals related to figure-ground segregation and feature integration. However, it is unknown whether this also affects perceptual integration itself. Therefore, we tested whether ketamine, a non-competitive NMDA receptor antagonist, reduces feature integration in humans. We administered a subanesthetic dose of ketamine to healthy subjects who performed a texture discrimination task in a placebo-controlled double blind within-subject design. We found that ketamine significantly impaired performance on the texture discrimination task compared to the placebo condition, while performance on a control fixation task was much less impaired. This effect is not merely due to task difficulty or a difference in sedation levels. We are the first to show a behavioral effect on feature integration by manipulating the NMDA receptor in humans. PMID:24223927

  17. NMDA Receptor Antagonist Ketamine Impairs Feature Integration in Visual Perception

    PubMed Central

    Meuwese, Julia D. I.; van Loon, Anouk M.; Scholte, H. Steven; Lirk, Philipp B.; Vulink, Nienke C. C.; Hollmann, Markus W.; Lamme, Victor A. F.

    2013-01-01

    Recurrent interactions between neurons in the visual cortex are crucial for the integration of image elements into coherent objects, such as in figure-ground segregation of textured images. Blocking N-methyl-D-aspartate (NMDA) receptors in monkeys can abolish neural signals related to figure-ground segregation and feature integration. However, it is unknown whether this also affects perceptual integration itself. Therefore, we tested whether ketamine, a non-competitive NMDA receptor antagonist, reduces feature integration in humans. We administered a subanesthetic dose of ketamine to healthy subjects who performed a texture discrimination task in a placebo-controlled double blind within-subject design. We found that ketamine significantly impaired performance on the texture discrimination task compared to the placebo condition, while performance on a control fixation task was much less impaired. This effect is not merely due to task difficulty or a difference in sedation levels. We are the first to show a behavioral effect on feature integration by manipulating the NMDA receptor in humans. PMID:24223927

  18. Interplay between non-NMDA and NMDA receptor activation during oscillatory wave propagation: Analyses of caffeine-induced oscillations in the visual cortex of rats.

    PubMed

    Yoshimura, Hiroshi; Sugai, Tokio; Kato, Nobuo; Tominaga, Takashi; Tominaga, Yoko; Hasegawa, Takahiro; Yao, Chenjuan; Akamatsu, Tetsuya

    2016-07-01

    Generation and propagation of oscillatory activities in cortical networks are important features of the brain. However, many issues related to oscillatory phenomena are unclear. We previously reported neocortical oscillation following caffeine treatment of rat brain slices. Input to the primary visual cortex (Oc1) generates N-methyl-d-aspartate (NMDA) receptor-dependent oscillations, and we proposed that the oscillatory signals originate in the secondary visual cortex (Oc2). Because non-NMDA and NMDA receptors cooperate in synaptic transmission, non-NMDA receptors may also play an important role in oscillatory activities. Here we investigated how non-NMDA receptor activities contribute to NMDA receptor-dependent oscillations by using optical recording methods. After induction of stable oscillations with caffeine application, blockade of NMDA receptors abolished the late stable oscillatory phase, but elicited 'hidden' non-NMDA receptor-dependent oscillation during the early depolarizing phase. An interesting finding is that the origin of the non-NMDA receptor-dependent oscillation moved from the Oc1, during the early phase, toward the origin of the NMDA receptor-dependent oscillation that is fixed in the Oc2. In addition, the frequency of the non-NMDA receptor-dependent oscillation was higher than that of the NMDA receptor-dependent oscillation. Thus, in one course of spatiotemporal oscillatory activities, the relative balance in receptor activities between non-NMDA and NMDA receptors gradually changes, and this may be due to the different kinetics of the two receptor types. These results suggest that interplay between the two receptor types in the areas of Oc1 and Oc2 may play an important role in oscillatory signal communication. PMID:27136667

  19. Differential regulation of AMPA receptor subunit trafficking by palmitoylation of two distinct sites.

    PubMed

    Hayashi, Takashi; Rumbaugh, Gavin; Huganir, Richard L

    2005-09-01

    Modification of AMPA receptor function is a major mechanism for the regulation of synaptic transmission and underlies several forms of synaptic plasticity. Post-translational palmitoylation is a reversible modification that regulates localization of many proteins. Here, we report that palmitoylation of the AMPA receptor regulates receptor trafficking. All AMPA receptor subunits are palmitoylated on two cysteine residues in their transmembrane domain (TMD) 2 and in their C-terminal region. Palmitoylation on TMD 2 is upregulated by the palmitoyl acyl transferase GODZ and leads to an accumulation of the receptor in the Golgi and a reduction of receptor surface expression. C-terminal palmitoylation decreases interaction of the AMPA receptor with the 4.1N protein and regulates AMPA- and NMDA-induced AMPA receptor internalization. Moreover, depalmitoylation of the receptor is regulated by activation of glutamate receptors. These data suggest that regulated palmitoylation of AMPA receptor subunits modulates receptor trafficking and may be important for synaptic plasticity. PMID:16129400

  20. Low Density Lipoprotein Receptor-related Protein 1 (LRP1) Modulates N-Methyl-d-aspartate (NMDA) Receptor-dependent Intracellular Signaling and NMDA-induced Regulation of Postsynaptic Protein Complexes*

    PubMed Central

    Nakajima, Chikako; Kulik, Akos; Frotscher, Michael; Herz, Joachim; Schäfer, Michael; Bock, Hans H.; May, Petra

    2013-01-01

    The lipoprotein receptor LRP1 is essential in neurons of the central nervous system, as was revealed by the analysis of conditional Lrp1-deficient mouse models. The molecular basis of its neuronal functions, however, is still incompletely understood. Here we show by immunocytochemistry, electron microscopy, and postsynaptic density preparation that LRP1 is located postsynaptically. Basal and NMDA-induced phosphorylation of the transcription factor cAMP-response element-binding protein (CREB) as well as NMDA target gene transcription are reduced in LRP1-deficient neurons. In control neurons, NMDA promotes γ-secretase-dependent release of the LRP1 intracellular domain (LRP1-ICD). However, pull-down and chromatin immunoprecipitation (ChIP) assays showed no direct interaction between the LRP1-ICD and either CREB or target gene promoters. On the other hand, NMDA-induced degradation of the postsynaptic scaffold protein PSD-95 was impaired in the absence of LRP1, whereas its ubiquitination was increased, indicating that LRP1 influences the composition of postsynaptic protein complexes. Accordingly, NMDA-induced internalization of the AMPA receptor subunit GluA1 was impaired in LRP1-deficient neurons. These results show a role of LRP1 in the regulation and turnover of synaptic proteins, which may contribute to the reduced dendritic branching and to the neurological phenotype observed in the absence of LRP1. PMID:23760271

  1. Memantine, an NMDA receptor antagonist, improves working memory deficits in DGKβ knockout mice.

    PubMed

    Kakefuda, Kenichi; Ishisaka, Mitsue; Tsuruma, Kazuhiro; Shimazawa, Masamitsu; Hara, Hideaki

    2016-09-01

    Diacylglycerol kinase (DGK) β is a type 1 isozyme of the DGK family. We previously reported that DGKβ was deeply involved in neurite spine formation, and DGKβ knockout (KO) mice exhibited behavioral abnormalities concerning spine formation, such as cognitive, emotional, and attentional impairment. Moreover, some of these abnormalities were ameliorated by the administration of a mood stabilizer. However, there is no data about how memory-improving drugs used in the treatment of Alzheimer's disease affect DGKβ KO mice. In the present study, we evaluated the effect of an anti-Alzheimer's drug, memantine on the working memory deficit observed in DGKβ KO mice. In the Y-maze test, the administration of memantine significantly improved working memory of DGKβ KO mice. We also found that the expression levels of the NR2A and NR2B N-methyl-d-aspartate (NMDA) receptor subunits were increased in the prefrontal cortex, but decreased in the hippocampus of DGKβ KO mice. These altered expression levels of NR2 subunits might be related to the effect of an NMDA receptor antagonist, memantine. Taken together, these findings may support the hypothesis that DGKβ has a pivotal role in cognitive function. PMID:27495014

  2. Inhibition of Morphine Tolerance and Dependence by the NMDA Receptor Antagonist MK-801

    NASA Astrophysics Data System (ADS)

    Trujillo, Keith A.; Akil, Huda

    1991-01-01

    The N-methyl-D-aspartate (NMDA) subtype of the glutamate receptor is an important mediator of several forms of neural and behavioral plasticity. The present studies examined whether NMDA receptors might be involved in the development of opiate tolerance and dependence, two examples of behavioral plasticity. The noncompetitive NMDA receptor antagonist MK-801 attenuated the development of tolerance to the analgesic effect of morphine without affecting acute morphine analgesia. In addition, MK-801 attenuated the development of morphine dependence as assessed by naloxone-precipitated withdrawal. These results suggest that NMDA receptors may be important in the development of opiate tolerance and dependence.

  3. NMDA receptors and fear extinction: implications for cognitive behavioral therapy.

    PubMed

    Davis, Michael

    2011-01-01

    Based primarily on studies that employ Pavlovian fear conditioning, extinction of conditioned fear has been found to be mediated by N-methyi-D-aspartate (NMDA) receptors in the amygdala and medial prefrontal cortex. This led to the discovery that an NMDA partial agonist, D-cycloserine, could facilitate fear extinction when given systemically or locally into the amygdala. Because many forms of cognitive behavioral therapy depend on fear extinction, this led to the successful use of D-cycloserine as an adjunct to psychotherapy in patients with so-called simple phobias (fear of heights), social phobia, obsessive-compulsive behavior, and panic disorder. Data in support of these conclusions are reviewed, along with some of the possible limitations of D-cycloserine as an adjunct to psychotherapy. PMID:22275851

  4. Agonist binding to the NMDA receptor drives movement of its cytoplasmic domain without ion flow.

    PubMed

    Dore, Kim; Aow, Jonathan; Malinow, Roberto

    2015-11-24

    The NMDA receptor (R) plays important roles in brain physiology and pathology as an ion channel. Here we examine the ion flow-independent coupling of agonist to the NMDAR cytoplasmic domain (cd). We measure FRET between fluorescently tagged cytoplasmic domains of GluN1 subunits of NMDARs expressed in neurons. Different neuronal compartments display varying levels of FRET, consistent with different NMDARcd conformations. Agonist binding drives a rapid and transient ion flow-independent reduction in FRET between GluN1 subunits within individual NMDARs. Intracellular infusion of an antibody targeting the GluN1 cytoplasmic domain blocks agonist-driven FRET changes in the absence of ion flow, supporting agonist-driven movement of the NMDARcd. These studies indicate that extracellular ligand binding to the NMDAR can transmit conformational information into the cell in the absence of ion flow. PMID:26553997

  5. Agonist binding to the NMDA receptor drives movement of its cytoplasmic domain without ion flow

    PubMed Central

    Dore, Kim; Aow, Jonathan; Malinow, Roberto

    2015-01-01

    The NMDA receptor (R) plays important roles in brain physiology and pathology as an ion channel. Here we examine the ion flow-independent coupling of agonist to the NMDAR cytoplasmic domain (cd). We measure FRET between fluorescently tagged cytoplasmic domains of GluN1 subunits of NMDARs expressed in neurons. Different neuronal compartments display varying levels of FRET, consistent with different NMDARcd conformations. Agonist binding drives a rapid and transient ion flow-independent reduction in FRET between GluN1 subunits within individual NMDARs. Intracellular infusion of an antibody targeting the GluN1 cytoplasmic domain blocks agonist-driven FRET changes in the absence of ion flow, supporting agonist-driven movement of the NMDARcd. These studies indicate that extracellular ligand binding to the NMDAR can transmit conformational information into the cell in the absence of ion flow. PMID:26553997

  6. Tissue plasminogen activator inhibits NMDA-receptor-mediated increases in calcium levels in cultured hippocampal neurons

    PubMed Central

    Robinson, Samuel D.; Lee, Tet Woo; Christie, David L.; Birch, Nigel P.

    2015-01-01

    NMDA receptors (NMDARs) play a critical role in neurotransmission, acting as essential mediators of many forms of synaptic plasticity, and also modulating aspects of development, synaptic transmission and cell death. NMDAR-induced responses are dependent on a range of factors including subunit composition and receptor location. Tissue-type plasminogen activator (tPA) is a serine protease that has been reported to interact with NMDARs and modulate NMDAR activity. In this study we report that tPA inhibits NMDAR-mediated changes in intracellular calcium levels in cultures of primary hippocampal neurons stimulated by low (5 μM) but not high (50 μM) concentrations of NMDA. tPA also inhibited changes in calcium levels stimulated by presynaptic release of glutamate following treatment with bicucculine/4-aminopyridine (4-AP). Inhibition was dependent on the proteolytic activity of tPA but was unaffected by α2-antiplasmin, an inhibitor of the tPA substrate plasmin, and receptor-associated protein (RAP), a pan-ligand blocker of the low-density lipoprotein receptor, two proteins previously reported to modulate NMDAR activity. These findings suggest that tPA can modulate changes in intracellular calcium levels in a subset of NMDARs expressed in cultured embryonic hippocampal neurons through a mechanism that involves the proteolytic activity of tPA and synaptic NMDARs. PMID:26500501

  7. Sexually dimorphic development and binding characteristics of NMDA receptors in the brain of the platyfish

    NASA Technical Reports Server (NTRS)

    Flynn, K. M.; Schreibman, M. P.; Yablonsky-Alter, E.; Banerjee, S. P.

    1999-01-01

    This study investigated age- and gender-specific variations in properties of the glutamate N-methyl-d-aspartate receptor (NMDAR) in a freshwater teleost, the platyfish (Xiphophorus maculatus). Prior localization of the immunoreactive (ir)-R1 subunit of the NMDAR protein (R1) in cells of the nucleus olfactoretinalis (NOR), a primary gonadotropin-releasing hormone (GnRH)-containing brain nucleus in the platyfish, suggests that NMDAR, as in mammals, is involved in modulation of the platyfish brain-pituitary-gonad (BPG) axis. The current study shows that the number of cells in the NOR displaying ir-R1 is significantly increased in pubescent and mature female platyfish when compared to immature and senescent animals. In males, there is no significant change in ir-R1 expression in the NOR at any time in their lifespan. The affinity of the noncompetitive antagonist ((3)H)MK-801 for the NMDAR is significantly increased in pubescent females while maximum binding of ((3)H)MK-801 to the receptor reaches a significant maximum in mature females. In males, both MK-801 affinity and maximum binding remain unchanged throughout development. This is the first report of gender differences in the association of NMDA receptors with neuroendocrine brain areas during development. It is also the first report to suggest NMDA receptor involvement in the development of the BPG axis in a nonmammalian vertebrate. Copyright 1999 Academic Press.

  8. Anti-NMDA Receptor Encephalitis in a Patient with Previous Psychosis and Neurological Abnormalities: A Diagnostic Challenge

    PubMed Central

    Heekin, R. David; Catalano, Maria C.; Frontera, Alfred T.; Catalano, Glenn

    2015-01-01

    Anti-N-methyl-D-aspartate (NMDA) receptor encephalitis is an autoimmune disorder characterized by IgG autoantibodies directed against the NR1 subunit of the NMDA glutamate receptor. Psychiatric symptoms are common and include psychosis, mania, depressed mood, aggression, and speech abnormalities. Neurological symptoms such as seizures, decreased responsiveness, dyskinesias, and other movement abnormalities and/or autonomic instability are frequently seen as well. We present the case of a woman who was followed up at our facility for over 14 years for the treatment of multiple neuropsychiatric symptoms. Initially, she presented with paresthesias, memory loss, and manic symptoms. Nine years later, she presented to our facility again, this time with left sided numbness, left eyelid droop, and word finding difficulties. Finally, five years later, she presented with manic symptoms, hallucinations, and memory impairment. During her hospitalization, she subsequently developed catatonic symptoms and seizures. During her stay, it was discovered that she was positive for anti-NMDA receptor antibodies and her symptoms responded well to appropriate therapy. This case demonstrates that it may be useful for clinicians to consider screening for anti-NMDA receptor antibodies in long-term patients with neuropsychiatric symptoms that have not adequately responded to therapy. PMID:26199781

  9. Differential sensitivity of medium- and large-sized striatal neurons to NMDA but not kainate receptor activation in the rat.

    PubMed

    Cepeda, C; Itri, J N; Flores-Hernández, J; Hurst, R S; Calvert, C R; Levine, M S

    2001-11-01

    Infrared videomicroscopy and differential interference contrast optics were used to identify medium- and large-sized neurons in striatal slices from young rats. Whole-cell patch-clamp recordings were obtained to compare membrane currents evoked by application of N-methyl-d-aspartate (NMDA) and kainate. Inward currents and current densities induced by NMDA were significantly smaller in large- than in medium-sized striatal neurons. The negative slope conductance for NMDA currents was greater in medium- than in large-sized neurons and more depolarization was required to remove the Mg2+ blockade. In contrast, currents induced by kainate were significantly greater in large-sized neurons whilst current densities were approximately equal in both cell types. Spontaneous excitatory postsynaptic currents occurred frequently in medium-sized neurons but were relatively infrequent in large-sized neurons. Excitatory postsynaptic currents evoked by electrical stimulation were smaller in large- than in medium-sized neurons. A final set of experiments assessed a functional consequence of the differential sensitivity of medium- and large-sized neurons to NMDA. Cell swelling was used to examine changes in somatic area in both neuronal types after prolonged application of NMDA or kainate. NMDA produced a time-dependent increase in somatic area in medium-sized neurons whilst it produced only minimal changes in large interneurons. In contrast, application of kainate produced significant swelling in both medium- and large-sized cells. We hypothesize that reduced sensitivity to NMDA may be due to variations in receptor subunit composition and/or the relative density of receptors in the two cell types. These findings help define the conditions that put neurons at risk for excitotoxic damage in neurological disorders. PMID:11860453

  10. The levels of the GluN2A NMDA receptor subunit are modified in both the neonatal and adult rat brain by an early experience involving denial of maternal contact.

    PubMed

    Manatos, V; Stylianopoulou, F; Stamatakis, A

    2016-01-26

    The composition of the N-methyl-d-aspartate receptor receptor in GluN2A/GluN2B subunits is important in determining its characteristics and its role in plasticity, a property of the brain which is known to be critically affected by early experiences. In the present work we employed an early experience model involving either receipt (RER) or denial (DER) of the expected reward of maternal contact within the context of learning by the pups of a T-maze on postnatal days (PND) 10-13. We investigated the effects of the RER and DER early experiences on GluN1, GluN2A and GluN2B levels in the prefrontal cortex (PFC), hippocampus and amygdala of the rat. We show that on PND13 the DER animals had lower GluN2A levels in the PFC. In adulthood DER males had higher GluN2A levels in the hippocampus, both under basal conditions and after exposure to a novel environment. The early experiences did not affect the response to the novelty. After exposure to a novel environment animals of all three groups (DER, RER, Control) responded with an increase in GluN2A levels in the brain areas examined. We did not detect any effects on GluN1 or GluN2B levels. The alterations in GluN2A levels observed in the DER animals could in part be responsible for their behavioral phenotype, described previously, which includes an increased susceptibility for the expression of depressive-like behavior. PMID:26679226

  11. ER to synapse trafficking of NMDA receptors

    PubMed Central

    Horak, Martin; Petralia, Ronald S.; Kaniakova, Martina; Sans, Nathalie

    2014-01-01

    Glutamate is the major excitatory neurotransmitter in the mammalian central nervous system. There are three distinct subtypes of ionotropic glutamate receptors (GluRs) that have been identified including 2-amino-3-(5-methyl-3-oxo-1,2-oxazol-4-yl)propanoic acid receptors (AMPARs), N-methyl-D-aspartate receptors (NMDARs) and kainate receptors. The most common GluRs in mature synapses are AMPARs that mediate the fast excitatory neurotransmission and NMDARs that mediate the slow excitatory neurotransmission. There have been large numbers of recent reports studying how a single neuron regulates synaptic numbers and types of AMPARs and NMDARs. Our current research is centered primarily on NMDARs and, therefore, we will focus in this review on recent knowledge of molecular mechanisms occurring (1) early in the biosynthetic pathway of NMDARs, (2) in the transport of NMDARs after their release from the endoplasmic reticulum (ER); and (3) at the plasma membrane including excitatory synapses. Because a growing body of evidence also indicates that abnormalities in NMDAR functioning are associated with a number of human psychiatric and neurological diseases, this review together with other chapters in this issue may help to enhance research and to gain further knowledge of normal synaptic physiology as well as of the etiology of many human brain diseases. PMID:25505872

  12. ER to synapse trafficking of NMDA receptors.

    PubMed

    Horak, Martin; Petralia, Ronald S; Kaniakova, Martina; Sans, Nathalie

    2014-01-01

    Glutamate is the major excitatory neurotransmitter in the mammalian central nervous system. There are three distinct subtypes of ionotropic glutamate receptors (GluRs) that have been identified including 2-amino-3-(5-methyl-3-oxo-1,2-oxazol-4-yl)propanoic acid receptors (AMPARs), N-methyl-D-aspartate receptors (NMDARs) and kainate receptors. The most common GluRs in mature synapses are AMPARs that mediate the fast excitatory neurotransmission and NMDARs that mediate the slow excitatory neurotransmission. There have been large numbers of recent reports studying how a single neuron regulates synaptic numbers and types of AMPARs and NMDARs. Our current research is centered primarily on NMDARs and, therefore, we will focus in this review on recent knowledge of molecular mechanisms occurring (1) early in the biosynthetic pathway of NMDARs, (2) in the transport of NMDARs after their release from the endoplasmic reticulum (ER); and (3) at the plasma membrane including excitatory synapses. Because a growing body of evidence also indicates that abnormalities in NMDAR functioning are associated with a number of human psychiatric and neurological diseases, this review together with other chapters in this issue may help to enhance research and to gain further knowledge of normal synaptic physiology as well as of the etiology of many human brain diseases. PMID:25505872

  13. Non-ionotropic signaling by the NMDA receptor: controversy and opportunity.

    PubMed

    Gray, John A; Zito, Karen; Hell, Johannes W

    2016-01-01

    Provocative emerging evidence suggests that the N-methyl-d-aspartate (NMDA) receptor can signal in the absence of ion flux through the receptor. This non-ionotropic signaling is thought to be due to agonist-induced conformational changes in the receptor, independently of channel opening. Non-ionotropic NMDA receptor signaling has been proposed to be sufficient to induce synaptic long-term depression (LTD), directly challenging the decades-old model that prolonged low-level calcium influx is required to induce LTD. Here, we briefly review these recent findings, focusing primarily on the potential role of non-ionotropic signaling in NMDA receptor-mediated LTD. Further reports concerning additional roles of non-ionotropic NMDA receptor signaling are also discussed. If validated, this new view of NMDA receptor-mediated signaling will usher in an exciting new era of exploring synapse function and dysfunction. PMID:27303637

  14. Non-ionotropic signaling by the NMDA receptor: controversy and opportunity

    PubMed Central

    Gray, John A.; Zito, Karen; Hell, Johannes W.

    2016-01-01

    Provocative emerging evidence suggests that the N-methyl-d-aspartate (NMDA) receptor can signal in the absence of ion flux through the receptor. This non-ionotropic signaling is thought to be due to agonist-induced conformational changes in the receptor, independently of channel opening. Non-ionotropic NMDA receptor signaling has been proposed to be sufficient to induce synaptic long-term depression (LTD), directly challenging the decades-old model that prolonged low-level calcium influx is required to induce LTD. Here, we briefly review these recent findings, focusing primarily on the potential role of non-ionotropic signaling in NMDA receptor-mediated LTD. Further reports concerning additional roles of non-ionotropic NMDA receptor signaling are also discussed. If validated, this new view of NMDA receptor-mediated signaling will usher in an exciting new era of exploring synapse function and dysfunction. PMID:27303637

  15. Cholesterol modulates open probability and desensitization of NMDA receptors

    PubMed Central

    Korinek, Miloslav; Vyklicky, Vojtech; Borovska, Jirina; Lichnerova, Katarina; Kaniakova, Martina; Krausova, Barbora; Krusek, Jan; Balik, Ales; Smejkalova, Tereza; Horak, Martin; Vyklicky, Ladislav

    2015-01-01

    NMDA receptors (NMDARs) are glutamate-gated ion channels that mediate excitatory neurotransmission in the CNS. Although these receptors are in direct contact with plasma membrane, lipid–NMDAR interactions are little understood. In the present study, we aimed at characterizing the effect of cholesterol on the ionotropic glutamate receptors. Whole-cell current responses induced by fast application of NMDA in cultured rat cerebellar granule cells (CGCs) were almost abolished (reduced to 3%) and the relative degree of receptor desensitization was increased (by seven-fold) after acute cholesterol depletion by methyl-β-cyclodextrin. Both of these effects were fully reversible by cholesterol repletion. By contrast, the responses mediated by AMPA/kainate receptors were not affected by cholesterol depletion. Similar results were obtained in CGCs after chronic inhibition of cholesterol biosynthesis by simvastatin and acute enzymatic cholesterol degradation to 4-cholesten-3-one by cholesterol oxidase. Fluorescence anisotropy measurements showed that membrane fluidity increased after methyl-β-cyclodextrin pretreatment. However, no change in fluidity was observed after cholesterol enzymatic degradation, suggesting that the effect of cholesterol on NMDARs is not mediated by changes in membrane fluidity. Our data show that diminution of NMDAR responses by cholesterol depletion is the result of a reduction of the open probability, whereas the increase in receptor desensitization is the result of an increase in the rate constant of entry into the desensitized state. Surface NMDAR population, agonist affinity, single-channel conductance and open time were not altered in cholesterol-depleted CGCs. The results of our experiments show that cholesterol is a strong endogenous modulator of NMDARs. Key points NMDA receptors (NMDARs) are tetrameric cation channels permeable to calcium; they mediate excitatory synaptic transmission in the CNS and their excessive activation can lead to

  16. Time and space profiling of NMDA receptor co-agonist functions.

    PubMed

    Mothet, Jean-Pierre; Le Bail, Matildé; Billard, Jean-Marie

    2015-10-01

    The N-Methyl D-Aspartic acid (NMDA) receptors (NMDAR) are key tetrameric ionotropic glutamate receptors that transduce glutamatergic signals throughout the central nervous system (CNS) and spinal cord. Although NMDARs are diverse in their subunit composition, subcellular localization, and biophysical and pharmacological properties, their activation always requires the binding of a co-agonist that has long been thought to be glycine. However, intense research over the last decade has challenged this classical model by showing that another amino acid, d-serine, is the preferential co-agonist for a subset of synaptic NMDARs in many areas of the adult brain. Nowadays, a totally new picture of glutamatergic synapses at work is emerging where both glycine and d-serine are involved in a complex interplay to regulate NMDAR functions in the CNS following time and space constraints. The purpose of this review was to highlight the particular role of each co-agonist in modulating NMDAR-dependent activities in healthy and diseased brains. We have herein integrated our most advanced knowledge of how glycine and d-serine may orchestrate synapse dynamics and drive neuronal network activity in a time- and synapse-specific manner and how changes in synaptic availability of these amino acids may contribute to cognitive impairments such as those associated with healthy aging, epilepsy, and schizophrenia. The N-Methyl D-Aspartic acid (NMDA) subtype of glutamate receptors are central to many physiological functions and are linked to brain disorders. Their functions require glutamate and a co-agonist d-serine or glycine. After years of intense research and controversy on the identity of the amino acid that serves as the right co-agonist, we are just entering a new era of consensus where glycine and d-serine are teaming up to regulate the function of different subsets of NMDA receptors and at different synapses during different time windows of brain development. PMID:26088787

  17. Behavioral Deficits and Subregion-Specific Suppression of LTP in Mice Expressing a Population of Mutant NMDA Receptors throughout the Hippocampus

    ERIC Educational Resources Information Center

    Chen, Philip E.; Errington, Michael L.; Kneussel, Matthias; Chen, Guiquan; Annala, Alexander J.; Rudhard, York H.; Rast, Georg F.; Specht, Christian G.; Tigaret, Cezar M.; Nassar, Mohammed A.; Morris, Richard G.M.; Bliss, Timothy V. P.; Schoepfer, Ralf

    2009-01-01

    The NMDA receptor (NMDAR) subunit GluN1 is an obligatory component of NMDARs without a known functional homolog and is expressed in almost every neuronal cell type. The NMDAR system is a coincidence detector with critical roles in spatial learning and synaptic plasticity. Its coincidence detection property is crucial for the induction of…

  18. Toxicological Differences Between NMDA Receptor Antagonists and Cholinesterase Inhibitors.

    PubMed

    Shi, Xiaodong; Lin, Xiaotian; Hu, Rui; Sun, Nan; Hao, Jingru; Gao, Can

    2016-08-01

    Cholinesterase inhibitors (ChEIs), represented by donepezil, rivastigmine, and galantamine, used to be the only approved class of drugs for the treatment of Alzheimer's disease. After the approval of memantine by the Food and Drug Administration (FDA), N-methyl-d-aspartic acid (NMDA) receptor antagonists have been recognized by authorities and broadly used in the treatment of Alzheimer's disease. Along with complementary mechanisms of action, NMDA antagonists and ChEIs differ not only in therapeutic effects but also in adverse reactions, which is an important consideration in clinical drug use. And the number of patients using NMDA antagonists and ChEIs concomitantly has increased, making the matter more complicated. Here we used the FDA Adverse Event Reporting System for statistical analysis , in order to compare the adverse events of memantine and ChEIs. In general, the clinical evidence confirmed the safety advantages of memantine over ChEIs, reiterating the precautions of clinical drug use and the future direction of antidementia drug development. PMID:26769920

  19. Cell-type Specific Development of NMDA Receptors in the Interneurons of Rat Prefrontal Cortex

    PubMed Central

    Wang, Huai-Xing; Gao, Wen-Jun

    2009-01-01

    In the prefrontal cortex, N-methyl-D-aspartic acid (NMDA) receptors are critical not only for normal prefrontal functions but also for the pathological processes of schizophrenia. Little is known, however, about the developmental properties of NMDA receptors in the functionally diverse subpopulations of interneurons. We investigated the developmental changes of NMDA receptors in rat prefrontal interneurons using patch clamp recording in cortical slices. We found that fast-spiking (FS) interneurons exhibited properties of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and NMDA currents distinct from those in regular spiking (RS) and low-threshold spiking (LTS) interneurons, particularly during the adolescent period. In juvenile animals, most (73%) of the FS cells demonstrated both AMPA and NMDA currents. The NMDA currents, however, gradually became undetectable during cortical development, with most (74%) of the FS cells exhibiting no NMDA current in adults. In contrast, AMPA and NMDA currents in RS and LTS interneurons were relatively stable, without significant changes from juveniles to adults. Moreover, even in FS cells with NMDA currents, the NMDA/AMPA ratio dramatically decreased during the adolescent period but returned to juvenile level in adults, compared to the relatively stable ratios in RS and LTS interneurons. These data suggest that FS interneurons in the PFC undergo dramatic changes in glutamatergic receptors during the adolescent period. These properties may make FS cells particularly sensitive and vulnerable to epigenetic stimulation, thus contributing to the onset of many psychiatric disorders, including schizophrenia. PMID:19242405

  20. Benzimidazolone bioisosteres of potent GluN2B selective NMDA receptor antagonists.

    PubMed

    Lütnant, Ines; Schepmann, Dirk; Wünsch, Bernhard

    2016-06-30

    Overactivation of the NMDA receptor is associated with excitotoxic events leading to neurodegenerative processes as observed during the development of Alzheimer's disease, ParFnson's disease, Chorea Huntington and epilepsy. Negative allosteric modulators addressing selectively the ifenprodil binding site of GluN2B subunit containing NMDA receptors are of major interest due to their neuroprotective potential accompanied by few side effects. Herein benzimidazolone bioisosteres of potent GluN2B antagonists 1-5 were designed and synthesized. A seven step sequence provided the central intermediate 19 in 28% yield. Elimination of water, methylation, epoxidation, epoxide rearrangement and finally reductive amination afforded the [7]annulenobenzimidazolone 30 with a 3-phenylpropylamino substituent in 6-position. Although 30 fits nicely into the pharmacophore of potent GluN2B antagonists, the gluN2B binding affinity of 30 was only moderate (Ki = 697 nM). Additionally, 30 shows low selectivity over the σ2 receptor (Ki = 549 nM). The moderate GluN2B affinity was explained by the rigid tricyclic structure of the [7]annulenobenzimidazolone 30. PMID:27061977

  1. Anti-NMDA Receptor Encephalitis During Pregnancy

    PubMed Central

    Mathis, Stéphane; Pin, Jean-Christophe; Pierre, Fabrice; Ciron, Jonathan; Iljicsov, Anna; Lamy, Matthias; Neau, Jean-Philippe

    2015-01-01

    Abstract Anti-N-methyl-D-aspartate receptor (anti-MMDAR) encephalitis is an immune-mediated encephalitis mainly affecting young women. We describe the case of a 21-year-old woman who developed a classical form of anti-NMDAR encephalitis during the 10th week of gestation. The patient had been treated with methylpredinsolone and intravenous immunoglobulins. Birth history of the child was normal, with normal APGAR score. The clinical symptoms of the patient have improved after a few months. This rare occurrence during pregnancy (only 9 other cases described) presents an opportunity to highlight the importance of making the earliest possible diagnosis of this treatable and potentially reversible encephalitis, and to educate gynecologists, psychiatrists, anesthetists, and neurologists on this potential cause of psychiatric and neurological manifestations during pregnancy. PMID:26131809

  2. PSD-95 Uncouples Dopamine-Glutamate Interaction in the D1/PSD-95/NMDA Receptor Complex

    PubMed Central

    Zhang, Jingping; Xu, Tai-Xiang; Hallett, Penelope J.; Watanabe, Masahiko; Grant, Seth G. N.; Isacson, Ole; Yao, Wei-Dong

    2008-01-01

    Classical dopaminergic signaling paradigms and emerging studies on direct physical interactions between the D1 dopamine (DA) receptor and the N-Methyl-D-Aspartate (NMDA) glutamate receptor predict a reciprocally facilitating, positive feedback loop. This loop, if not controlled, may cause concomitant overactivation of both D1 and NMDA receptors, triggering neurotoxicity. Endogenous protective mechanisms must exist. Here we show that PSD-95, a prototypical structural and signaling scaffold in the postsynaptic density, inhibits D1-NMDA receptor association and uncouples NMDA receptor-dependent enhancement of D1 signaling. This uncoupling is achieved, at least in part, via a disinhibition mechanism by which PSD-95 abolishes NMDA receptor-dependent inhibition of D1 internalization. Knockdown of PSD-95 immobilizes D1 receptors on the cell surface and escalates NMDA receptor-dependent D1 cAMP signaling in neurons. Thus, in addition to its role in receptor stabilization and synaptic plasticity, PSD-95 acts as a brake on the D1-NMDA receptor complex and dampens the interaction between them. PMID:19261890

  3. Essential involvement of the NMDA receptor in ethanol preconditioning-dependent neuroprotection from amyloid-betain vitro.

    PubMed

    Mitchell, Robert M; Neafsey, Edward J; Collins, Michael A

    2009-10-01

    In several epidemiological studies, moderate ethanol consumption has been associated with reduced risks of cognitive decline or Alzheimer's dementia. Of potential relevance is that brain cultures preconditioned with moderate ethanol concentrations are resistant to neurotoxic Alzheimer's amyloid-beta (Abeta) peptides. Using rat cerebellar mixed cultures we investigated whether certain membrane receptors were early 'sensors' in moderate ethanol preconditioning (MEP). In a 6-day MEP protocol (30 mM ethanol), neuroprotection from Abeta25-35 was undiminished by antagonism during the first 3 days of either adenosine A(1) or Galpha(i/o) protein-coupled receptors. However, similar cotreatment with memantine or DL-2-amino-5-phosphono-pentanoic acid (AP-5), antagonists of NMDA receptors (NMDAR), abolished neuroprotection, indicating key early involvement of this ionotropic glutamate receptor. Also in these cultures, directly activating NMDAR using subexcitotoxic NMDA preconditioning prevented Abeta neurotoxicity. By day 2 of MEP, we observed increased levels of NMDAR subunits NR1, NR2B, and NR2C that persisted through day 6. Interestingly, memantine co-exposure blocked elevations in the obligatory NR1 subunit. Furthermore, 2 days of MEP significantly increased two indicators of synaptic NMDAR localization, NR2B phospho-Tyr1472, and post-synaptic density 95 scaffolding protein. The results indicate that ethanol preconditioning-dependent neuroprotection is associated with early increases in NR subunits concomitant with enhancement of synaptic localization and activity of NMDAR. PMID:19694907

  4. Enhanced Polyubiquitination of Shank3 and NMDA receptor in a mouse model of Autism

    PubMed Central

    Bangash, M Ali; Park, Joo Min; Melnikova, Tatiana; Wang, Dehua; Jeon, Soo Kyeong; Lee, Deidre; Syeda, Sbaa; Kim, Juno; Kouser, Mehreen; Schwartz, Joshua; Cui, Yiyuan; Zhao, Xia; Speed, Haley E.; Kee, Sara E.; Tu, Jian Cheng; Hu, Jia-Hua; Petralia, Ronald S.; Linden, David J.; Powell, Craig M.; Savonenko, Alena; Xiao, Bo; Worley, Paul F.

    2011-01-01

    Summary We have created a mouse genetic model that mimics a human mutation of Shank3 that deletes the C-terminus and is associated with autism. Expressed as a single copy [Shank3(+/ΔC) mice], Shank3ΔC protein interacts with the WT gene product and results in >90 % reduction of Shank3 at synapses. This “gain of function” phenotype is linked to increased polyubiquitination of WT Shank3 and its redistribution into proteasomes. Similarly, the NR1 subunit of the NMDA receptor is reduced at synapses with increased polyubiquitination. Assays of post-synaptic density proteins, spine morphology and synapse number are unchanged in Shank3(+/ΔC) mice, but the amplitude of NMDAR responses is reduced together with reduced NMDAR-dependent LTP and LTD. Reciprocally, mGluR-dependent LTD is markedly enhanced. Shank3(+/ΔC) mice show behavioral deficits suggestive of autism and reduced NMDA receptor function. These studies reveal a mechanism distinct from haploinsufficiency by which mutations of Shank3 can evoke an autism-like disorder. PMID:21565394

  5. PSD-95 and Calcineurin Control the Sensitivity of NMDA Receptors to Calpain Cleavage in Cortical Neurons

    PubMed Central

    Yuen, Eunice Y.; Ren, Yi; Yan, Zhen

    2010-01-01

    The N-methyl-D-aspartate receptor (NMDAR) is a Ca2+-permeable glutamate receptor mediating many neuronal functions under normal and pathological conditions. Ca2+-influx via NMDARs activates diverse intracellular targets, including Ca2+-dependent protease calpain. Biochemical studies suggest that NR2A and NR2B subunits of NMDARs are substrates of calpain. Our physiological data showed that calpain, activated by prolonged NMDA treatment (100 µM, 5 min) of cultured cortical neurons, irreversibly decreased the whole-cell currents mediated by extrasynaptic NMDARs. Animals exposed to transient forebrain ischemia, a condition that activates calpain, exhibited the reduced NMDAR current density and the lower full-length NR2A/B level in a calpain-dependent manner. Disruption of the association between NMDARs and the scaffolding protein PSD-95 facilitated the calpain regulation of synaptic NMDAR responses and NR2 cleavage in cortical slices, while inhibition of calcineurin activity blocked the calpain effect on NMDAR currents and NR2 cleavage. Calpain-cleaved NR2B subunits were removed from the cell surface. Moreover, cell viability assays showed that calpain, by targeting NMDARs, provided a negative feedback to dampen neuronal excitability in excitotoxic conditions. These data suggest that calpain activation suppresses NMDAR function via proteolytic cleavage of NR2 subunits in vitro and in vivo, and the susceptibility of NMDARs to calpain cleavage is controlled by PSD-95 and calcineurin. PMID:18445709

  6. The Emergence of NMDA Receptor Metabotropic Function: Insights from Imaging

    PubMed Central

    Dore, Kim; Aow, Jonathan; Malinow, Roberto

    2016-01-01

    The NMDA receptor (R) participates in many important physiological and pathological processes. For example, its activation is required for both long-term potentiation (LTP) and long-term depression (LTD) of synaptic transmission, cellular models of learning and memory. Furthermore, it may play a role in the actions of amyloid-beta on synapses as well as in the signaling leading to cell death following stroke. Until recently, these processes were thought to be mediated by ion-flux through the receptor. Using a combination of imaging and electrophysiological approaches, ion-flux independent functions of the NMDAR were recently examined. In this review, we will discuss the role of metabotropic NMDAR function in LTD and synaptic dysfunction. PMID:27516738

  7. The Emergence of NMDA Receptor Metabotropic Function: Insights from Imaging.

    PubMed

    Dore, Kim; Aow, Jonathan; Malinow, Roberto

    2016-01-01

    The NMDA receptor (R) participates in many important physiological and pathological processes. For example, its activation is required for both long-term potentiation (LTP) and long-term depression (LTD) of synaptic transmission, cellular models of learning and memory. Furthermore, it may play a role in the actions of amyloid-beta on synapses as well as in the signaling leading to cell death following stroke. Until recently, these processes were thought to be mediated by ion-flux through the receptor. Using a combination of imaging and electrophysiological approaches, ion-flux independent functions of the NMDAR were recently examined. In this review, we will discuss the role of metabotropic NMDAR function in LTD and synaptic dysfunction. PMID:27516738

  8. Serotonin and NMDA receptors in respiratory long-term facilitation

    PubMed Central

    Ling, Liming

    2008-01-01

    Some have postulated that long-term facilitation (LTF), a persistent augmentation of respiratory activity after episodic hypoxia, may play a beneficial role in helping stabilize upper airway patency in obstructive sleep apnea (OSA) patients. However, the neuronal and cellular mechanisms underlying this plasticity of respiratory motor behavior are still poorly understood. The main purpose of this review is to summarize recent findings about serotonin and NMDA receptors involved in both LTF and its enhancement after chronic intermittent hypoxia (CIH). The potential roles of these receptors in the initiation, formation and/or maintenance of LTF, as well as the CIH effect on LTF, will be discussed. As background, different paradigms for the stimulus protocol, different patterns of LTF expression and their mechanistic implications in LTF will also be discussed. PMID:18606575

  9. Multiple effects of copper on NMDA receptor currents.

    PubMed

    Marchetti, Carla; Baranowska-Bosiacka, Irena; Gavazzo, Paola

    2014-01-13

    Copper (Cu) is an essential metal present in the human brain and released from synaptic vesicles following neuronal depolarization. Cu is known to reduce the NMDA receptor (NR) current with IC50≈20 µM. We have studied the effect of Cu on the NR current in cultured neonatal rat cerebellum granule cells (CGC) and in transiently transfected HEK293 cells (HEK), expressing either GluN1/GLUN2A or GluN1/GluN2B receptors. In CGCs, Cu causes a potentiation of the NR current at concentrations <30 µM (EC50=4.6 µM) and a block at higher concentrations (IC50=24 µM). In Fura2 loaded CGCs, Cu (≤30 µM) caused an increase of NMDA-driven calcium influx. This facilitating effect was prevented by pre-treatment with the reducing agent DTT. Cu also caused an increase of the NR current in GluN1/GluN2A receptors (EC50=2 µM) and a block at higher concentrations (IC50=26 µM). Both facilitation and inhibition were independent of voltage. The effect of Cu was quantitatively similar in GluN1/GluN2B receptors, which were potentiated by 10 µM and inhibited by 100 µM Cu. Potentiation was absent in mutants deleted of their entire amino terminal domain (ATD) of the protein, suggesting an involvement of this region in the interaction. These results indicate that Cu can facilitate the NR current at lower concentrations than those required for blocking it; this effect can have consequences on the activity of the metal at synaptic and extrasynaptic sites. PMID:24161827

  10. Effects of NMDA receptor inhibition by phencyclidine on the neuronal differentiation of PC12 cells.

    PubMed

    Lee, Eunsook; Williams, Zakia; Goodman, Carl B; Oriaku, Ebenezer T; Harris, Cynthia; Thomas, Mathews; Soliman, Karam F A

    2006-07-01

    Phencyclidine (PCP) is a non-competitive N-methyl-d-aspartate (NMDA) receptor antagonist and exposing the developing brain to PCP has been shown to cause deficits in neurobehavioral functions. In the present study we tested the effects of PCP, as an NMDA receptor inhibitor, on the neuronal differentiation and biogenic amines levels including norepinephrine (NE), epinephrine, dopamine, 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), serotonin (5-HT), and 5-hydroxyindole-3-acetic acid (5-HIAA) in the rat pheochromocytoma (PC12) cells. After PC12 cells were differentiated with nerve growth factor (NGF) in the presence of PCP, NMDA binding kinetics, biogenic amines analysis and NMDA receptor protein expression assay were conducted. The results showed that NMDA receptor binding activities were significantly increased after differentiated with NGF in PC12 cells. B(max) values were increased in differentiated cells by four-folds, whereas K(d) values were not changed. All of biogenic amines were significantly increased in differentiated cells. On the other hand, PCP at 50 and 100 microM inhibited neuronal differentiation in a dose-dependent manner in NGF-stimulated PC12 cells without affecting cell viability. PCP treatment during differentiation significantly reduced NMDA binding activity and biogenic amine levels. Western blotting analysis revealed that NMDA receptor protein expression was significantly higher in NGF-differentiated cells and PCP treatment decreased the expression of NMDA receptor proteins. These results indicate that NMDA receptor functions and monoaminergic nervous systems are significantly stimulated during NGF-induced differentiation. PCP suppresses neuronal outgrowth and hampers neuronal functions possibly by inhibiting NMDA receptor functions and biogenic amine production, implying the suppressive effects of PCP exposure on neuronal developments. PMID:16580729

  11. Kinetic contributions to gating by interactions unique to N-methyl-D-aspartate (NMDA) receptors.

    PubMed

    Borschel, William F; Cummings, Kirstie A; Tindell, LeeAnn K; Popescu, Gabriela K

    2015-10-30

    Among glutamate-gated channels, NMDA receptors produce currents that subside with unusually slow kinetics, and this feature is essential to the physiology of central excitatory synapses. Relative to the homologous AMPA and kainate receptors, NMDA receptors have additional intersubunit contacts in the ligand binding domain that occur at both conserved and non-conserved sites. We examined GluN1/GluN2A single-channel currents with kinetic analyses and modeling to probe these class-specific intersubunit interactions for their role in glutamate binding and receptor gating. We found that substitutions that eliminate such interactions at non-conserved sites reduced stationary gating, accelerated deactivation, and imparted sensitivity to aniracetam, an AMPA receptor-selective positive modulator. Abolishing unique contacts at conserved sites also reduced stationary gating and accelerated deactivation. These results show that contacts specific to NMDA receptors, which brace the heterodimer interface within the ligand binding domain, stabilize actively gating receptor conformations and result in longer bursts and slower deactivations. They support the view that the strength of the heterodimer interface modulates gating in both NMDA and non-NMDA receptors and that unique interactions at this interface are responsible in part for basic differences between the kinetics of NMDA and non-NMDA currents at glutamatergic synapses. PMID:26370091

  12. The role of non-receptor protein tyrosine kinases in the excitotoxicity induced by the overactivation of NMDA receptors.

    PubMed

    Sun, Yongjun; Chen, You; Zhan, Liying; Zhang, Linan; Hu, Jie; Gao, Zibin

    2016-04-01

    Protein tyrosine phosphorylation is one of the primary modes of regulation of N-methyl-d-aspartate (NMDA) receptors. The non-receptor tyrosine kinases are one of the two types of protein tyrosine kinases that are involved in this process. The overactivation of NMDA receptors is a primary reason for neuron death following cerebral ischemia. Many studies have illustrated the important role of non-receptor tyrosine kinases in ischemia insults. This review introduces the roles of Src, Fyn, focal adhesion kinase, and proline-rich tyrosine kinase 2 in the excitotoxicity induced by the overactivation of NMDA receptors following cerebral ischemia. PMID:26540220

  13. The Role of NMDA Receptor Subtypes in Short-Term Plasticity in the Rat Entorhinal Cortex

    PubMed Central

    Chamberlain, Sophie E. L.; Yang, Jian; Jones, Roland S. G.

    2008-01-01

    We have previously shown that spontaneous release of glutamate in the entorhinal cortex (EC) is tonically facilitated via activation of presynaptic NMDA receptors (NMDAr) containing the NR2B subunit. Here we show that the same receptors mediate short-term plasticity manifested by frequency-dependent facilitation of evoked glutamate release at these synapses. Whole-cell patch-clamp recordings were made from layer V pyramidal neurones in rat EC slices. Evoked excitatory postsynaptic currents showed strong facilitation at relatively low frequencies (3 Hz) of activation. Facilitation was abolished by an NR2B-selective blocker (Ro 25-6981), but unaffected by NR2A-selective antagonists (Zn2+, NVP-AAM077). In contrast, postsynaptic NMDAr-mediated responses could be reduced by subunit-selective concentrations of all three antagonists. The data suggest that NMDAr involved in presynaptic plasticity in layer V are exclusively NR1/NR2B diheteromers, whilst postsynaptically they are probably a mixture of NR1/NR2A, NR1/NR2B diheteromers and NR1/NR2A/NR2B triheteromeric receptors. PMID:18989370

  14. NAAG fails to antagonize synaptic and extrasynaptic NMDA receptors in cerebellar granule neurons.

    PubMed

    Losi, G; Vicini, S; Neale, J

    2004-03-01

    The peptide transmitter N-acetylaspartylglutamate (NAAG) selectively activates the group II metabotropic glutamate receptors. Several reports also suggest that this peptide acts as a partial agonist at N-methyl-D-aspartate (NMDA) receptors but its putative antagonist effects have not been directly tested. To do this, we used whole cell recordings from cerebellar granule cells (CGC) in culture that allow the highest possible resolution of NMDA channel activation. When CGC were activated with equimolar concentrations of NMDA and NAAG, the peptide failed to alter the peak current elicited by NMDA. Very high concentrations of NAAG (100-200 microM) did not significantly reduce the current elicited by 10 microM NMDA or 0.1 microM glutamate, while 400 microM NAAG produced only a very small (less than 15%) reduction in these whole cell currents. Similarly, NAAG (400 microM) failed to significantly alter the average decay time constant or the peak amplitude of NMDA receptor-mediated miniature excitatory post-synaptic currents (mEPSCs). We conclude that high concentrations of the peptide do not exert physiologically relevant antagonist actions on synaptic NMDA receptor activation following vesicular release of glutamate. As an agonist, purified NAAG was found to be at least 10,000-fold less potent than glutamate in increasing "background" current via NMDA receptors on CGC. Inasmuch as it is difficult to confirm that NAAG preparations are completely free from contamination with glutamate at the 0.01% level, the peptide itself appears unlikely to have a direct agonist activity at the NMDA receptor subtypes found in CGC. Recent reports indicate that enhancing the activity of endogenous NAAG may be an important therapeutic approach to excitotoxicity and chronic pain perception. These effects are likely mediated by group II mGluRs, not NMDA receptors. PMID:14975672

  15. Ring finger protein 10 is a novel synaptonuclear messenger encoding activation of NMDA receptors in hippocampus

    PubMed Central

    Dinamarca, Margarita C; Guzzetti, Francesca; Karpova, Anna; Lim, Dmitry; Mitro, Nico; Musardo, Stefano; Mellone, Manuela; Marcello, Elena; Stanic, Jennifer; Samaddar, Tanmoy; Burguière, Adeline; Caldarelli, Antonio; Genazzani, Armando A; Perroy, Julie; Fagni, Laurent; Canonico, Pier Luigi; Kreutz, Michael R; Gardoni, Fabrizio; Luca, Monica Di

    2016-01-01

    Synapses and nuclei are connected by bidirectional communication mechanisms that enable information transfer encoded by macromolecules. Here, we identified RNF10 as a novel synaptonuclear protein messenger. RNF10 is activated by calcium signals at the postsynaptic compartment and elicits discrete changes at the transcriptional level. RNF10 is enriched at the excitatory synapse where it associates with the GluN2A subunit of NMDA receptors (NMDARs). Activation of synaptic GluN2A-containing NMDARs and induction of long term potentiation (LTP) lead to the translocation of RNF10 from dendritic segments and dendritic spines to the nucleus. In particular, we provide evidence for importin-dependent long-distance transport from synapto-dendritic compartments to the nucleus. Notably, RNF10 silencing prevents the maintenance of LTP as well as LTP-dependent structural modifications of dendritic spines. DOI: http://dx.doi.org/10.7554/eLife.12430.001 PMID:26977767

  16. Nr3a-containing NMDA receptors promote neurotransmitter release and spike timing-dependent plasticity

    PubMed Central

    Larsen, Rylan S.; Corlew, Rebekah J.; Henson, Maile A.; Roberts, Adam C.; Mishina, Masayoshi; Watanabe, Masahiko; Lipton, Stuart A.; Nakanishi, Nobuki; Pérez-Otaño, Isabel; Weinberg, Richard J.; Philpot, Benjamin D.

    2012-01-01

    Recent evidence suggests that presynaptic-acting NMDA receptors (preNMDARs) are important for neocortical synaptic transmission and plasticity. We found that unique properties of the Nr3a subunit enable preNMDARs to enhance spontaneous and evoked glutamate release and that Nr3a is required for spike timing–dependent long-term depression in the juvenile mouse visual cortex. In the mature cortex, Nr2b-containing preNMDARs enhanced neurotransmission in the absence of magnesium, indicating that presynaptic NMDARs may function under depolarizing conditions throughout life. Our findings indicate that Nr3a relieves preNMDARs from the dual-activation requirement of ligand-binding and depolarization; the developmental removal of Nr3a limits preNMDAR functionality by restoring this associative property. PMID:21297630

  17. NMDA Receptor Plasticity in the Hypothalamic Paraventricular Nucleus Contributes to the Elevated Blood Pressure Produced by Angiotensin II

    PubMed Central

    Wang, Gang; Coleman, Christal G.; Chan, June; Ogorodnik, Evgeny; Van Kempen, Tracey A.; Milner, Teresa A.; Butler, Scott D.; Young, Colin N.; Davisson, Robin L.; Iadecola, Costantino; Pickel, Virginia M.

    2015-01-01

    Hypertension induced by angiotensin II (Ang II) is associated with glutamate-dependent dysregulation of the hypothalamic paraventricular nucleus (PVN). Many forms of glutamate-dependent plasticity are mediated by NMDA receptor GluN1 subunit expression and the distribution of functional receptor to the plasma membrane of dendrites. Here, we use a combined ultrastructural and functional analysis to examine the relationship between PVN NMDA receptors and the blood pressure increase induced by chronic infusion of a low dose of Ang II. We report that the increase in blood pressure produced by a 2 week administration of a subpressor dose of Ang II results in an elevation in plasma membrane GluN1 in dendrites of PVN neurons in adult male mice. The functional implications of these observations are further demonstrated by the finding that GluN1 deletion in PVN neurons attenuated the Ang II-induced increases in blood pressure. These results indicate that NMDA receptor plasticity in PVN neurons significantly contributes to the elevated blood pressure mediated by Ang II. PMID:26134639

  18. A specific role for NR2A-containing NMDA receptors in the maintenance of parvalbumin and GAD67 immunoreactivity in cultured interneurons.

    PubMed

    Kinney, Jefferson W; Davis, Christopher N; Tabarean, Iustin; Conti, Bruno; Bartfai, Tamas; Behrens, M Margarita

    2006-02-01

    Several lines of evidence suggest that a hypoglutamatergic condition may induce a phenotypic loss of cortical parvalbumin (PV)-positive GABAergic interneurons, such as that observed in brain tissue of schizophrenic subjects. However, it is not known whether the loss of PV interneurons is a consequence of the hypoglutamatergic condition or a secondary aspect of the disease. We characterized the signaling and subunit expression of NMDA receptors in cultured cortical PV interneurons and determined whether a hypoglutamatergic condition, created by direct application of sublethal concentrations of ketamine or subunit-selective NMDA receptor antagonists, can affect the expression of the GABAergic markers as observed in vivo. Real-time PCR performed on mRNA isolated from single neurons showed that PV interneurons present a fivefold higher NR2A/NR2B ratio than pyramidal neurons. Brief, nontoxic, exposure to NMDA led to an increase in ERK1/2 (extracellular signal-regulated kinase 1/2) and cAMP response element-binding protein phosphorylation in PV interneurons, and this increase was blocked by the NR2A-selective antagonist NVP-AAM077. Application of the nonselective NMDA receptor antagonist ketamine, at sublethal concentrations, induced a time and dose-dependent decrease in parvalbumin and GAD67 immunoreactivity specifically in PV interneurons. These effects were reversible and were also observed with the NR2A-selective antagonist, whereas the NR2B-selective antagonist Ro-25-6981 only partially reduced GAD67 immunoreactivity. Coexposure to the calcium channel opener BayK, or the group I metabotropic glutamate receptor agonist DHPG [(RS)-3,5-dihydroxyphenylglycine] attenuated the decrease in GAD67 and parvalbumin induced by the NMDA receptor antagonists. These results suggest that the activity of NR2A-containing NMDA receptors play a pivotal role in the maintenance of the GABAergic function of PV interneurons. PMID:16452684

  19. The relationship between NMDA receptor function and the high ammonia tolerance of anoxia-tolerant goldfish.

    PubMed

    Wilkie, Michael P; Pamenter, Matthew E; Duquette, Stephanie; Dhiyebi, Hadi; Sangha, Navjeet; Skelton, Geoffrey; Smith, Matthew D; Buck, Leslie T

    2011-12-15

    survival time by 1.5-2.0-fold during exposure to 2 mmol l(-1) ammonia, suggesting that excitotoxic cell death contributes to ammonia toxicity in this species. In contrast, similar doses of MK801 or ethanol had no effect on ammonia-challenged (8-9.5 mmol l(-1) T(Amm)) goldfish survival times, suggesting that greater resistance to excitotoxic cell death contributes to the high ammonia-tolerance of the goldfish. Whole-cell recordings measured in isolated brain slices of goldfish telencephalon during in vitro exposure to 5 mmol l(-1) or 10 mmol l(-1) T(Amm) reversibly potentiated NMDA receptor currents. This observation suggested that goldfish neurons may not be completely resistant to ammonia-induced excitotoxicity. Subsequent western blot and densitometric analyses revealed that NMDA receptor NR1 subunit abundance was 40-60% lower in goldfish exposed to 3-5 mmol l(-1) T(Amm) for 5 days, which was followed by a restoration of NR1 subunit abundance after 3 days recovery in ammonia-free water. We conclude that the goldfish brain may be protected from excitotoxicity by downregulating the abundance of functional NMDA receptors during periods when it experiences increased internal ammonia. PMID:22116753

  20. Reduction in Ventral Midbrain NMDA Receptors Reveals Two Opposite Modulatory Roles for Glutamate on Reward

    PubMed Central

    Hernandez, Giovanni; Khodami-Pour, Ali; Lévesque, Daniel; Rompré, Pierre-Paul

    2015-01-01

    Glutamate is a major component of the reward circuitry and recent clinical studies suggest that new molecules that would target glutamate neurotransmission are most likely to constitute more effective medications for mood disorders. It is well known that activation of N-methyl-D-aspartate glutamate receptors (NMDARs) initiates dopamine burst firing, a mode associated with reward signaling; but NMDARs also contribute to the maintenance of an inhibitory drive to dopamine neurons. Such opposite modulatory functions imply that different subtypes of NMDARs are expressed on different ventral midbrain (VM) neurons and/or afferent inputs to dopamine neurons. By using the small interfering RNA (siRNA) technique, we studied the effects of VM downregulation of NMDAR subunits GluN1, GluN2A, and GluN2D on reward induced by dorsal raphe electrical stimulation. Reward thresholds were measured before and 24 h after each of three consecutive daily bilateral microinjections of siRNA for the targeted receptor subunit(s) or non-active RNA sequence. After the last measurement, reward thresholds were reassessed following a bilateral microinjection of the preferred GluN2A-NMDA antagonist, (2R,4S)-4-(3-Phosphopropyl)-2-piperidinecarboxylic acid (PPPA). Western-blot analysis showed that siRNAs reduced GluN1- and GluN2A-containing receptors whereas behavioral tests showed that only a reduction in GluN1 produced reward attenuation. Despite NMDAR reduction, reward-enhancing effect of PPPA remained unchanged. We conclude that VM glutamate relays the reward signal initiated by dorsal raphe electrical stimulation by acting on NMDARs devoid of GluN2A/2D subunits and exerts an inhibition on this reward signal by acting on GluN2A-containing NMDARs most likely located on afferent terminals. PMID:25578795

  1. Reduction in Ventral Midbrain NMDA Receptors Reveals Two Opposite Modulatory Roles for Glutamate on Reward.

    PubMed

    Hernandez, Giovanni; Khodami-Pour, Ali; Lévesque, Daniel; Rompré, Pierre-Paul

    2015-06-01

    Glutamate is a major component of the reward circuitry and recent clinical studies suggest that new molecules that would target glutamate neurotransmission are most likely to constitute more effective medications for mood disorders. It is well known that activation of N-methyl-D-aspartate glutamate receptors (NMDARs) initiates dopamine burst firing, a mode associated with reward signaling; but NMDARs also contribute to the maintenance of an inhibitory drive to dopamine neurons. Such opposite modulatory functions imply that different subtypes of NMDARs are expressed on different ventral midbrain (VM) neurons and/or afferent inputs to dopamine neurons. By using the small interfering RNA (siRNA) technique, we studied the effects of VM downregulation of NMDAR subunits GluN1, GluN2A, and GluN2D on reward induced by dorsal raphe electrical stimulation. Reward thresholds were measured before and 24 h after each of three consecutive daily bilateral microinjections of siRNA for the targeted receptor subunit(s) or non-active RNA sequence. After the last measurement, reward thresholds were reassessed following a bilateral microinjection of the preferred GluN2A-NMDA antagonist, (2R,4S)-4-(3-Phosphopropyl)-2-piperidinecarboxylic acid (PPPA). Western-blot analysis showed that siRNAs reduced GluN1- and GluN2A-containing receptors whereas behavioral tests showed that only a reduction in GluN1 produced reward attenuation. Despite NMDAR reduction, reward-enhancing effect of PPPA remained unchanged. We conclude that VM glutamate relays the reward signal initiated by dorsal raphe electrical stimulation by acting on NMDARs devoid of GluN2A/2D subunits and exerts an inhibition on this reward signal by acting on GluN2A-containing NMDARs most likely located on afferent terminals. PMID:25578795

  2. Hippocampus NMDA receptors selectively mediate latent extinction of place learning.

    PubMed

    Goodman, Jarid; Gabriele, Amanda; Packard, Mark G

    2016-09-01

    Extinction of maze learning may be achieved with or without the animal performing the previously acquired response. In typical "response extinction," animals are given the opportunity to make the previously acquired approach response toward the goal location of the maze without reinforcement. In "latent extinction," animals are not given the opportunity to make the previously acquired response and instead are confined to the previous goal location without reinforcement. Previous evidence indicates that the effectiveness of these protocols may depend on the type of memory being extinguished. Thus, one aim of the present study was to further examine the effectiveness of response and latent extinction protocols across dorsolateral striatum (DLS)-dependent response learning and hippocampus-dependent place learning tasks. In addition, previous neural inactivation experiments indicate a selective role for the hippocampus in latent extinction, but have not investigated the precise neurotransmitter mechanisms involved. Thus, the present study also examined whether latent extinction of place learning might depend on NMDA receptor activity in the hippocampus. In experiment 1, adult male Long-Evans rats were trained in a response learning task in a water plus-maze, in which animals were reinforced to make a consistent body-turn response to reach an invisible escape platform. Results indicated that response extinction, but not latent extinction, was effective at extinguishing memory in the response learning task. In experiment 2, rats were trained in a place learning task, in which animals were reinforced to approach a consistent spatial location containing the hidden escape platform. In experiment 2, animals also received intra-hippocampal infusions of the NMDA receptor antagonist 2-amino-5-phosphopentanoic acid (AP5; 5.0 or 7.5 ug/0.5 µg) or saline vehicle immediately before response or latent extinction training. Results indicated that both extinction protocols were

  3. A dual mechanism for impairment of GABAA receptor activity by NMDA receptor activation in rat cerebellum granule cells.

    PubMed

    Robello, M; Amico, C; Cupello, A

    1997-01-01

    The function of the GABAA receptor has been studied using the whole cell voltage clamp recording technique in rat cerebellum granule cells in culture. Activation of NMDA-type glutamate receptors causes a reduction in the effect of GABA. Full GABAA receptor activity was recovered after washing out NMDA and NMDA action was prevented in a Mg+2 containing medium. The NMDA effect was also absent when extracellular Ca+2 was replaced by Ba+2 and when 10 mM Bapta was present in the intracellular solution. Charge accumulations via voltage activated Ca+2 channels greater than the ones via NMDA receptors do not cause any reduction in GABAA receptor function, suggesting that Ca+2 influx through NMDA receptor channels is critical for the effect. The NMDA effect was reduced by including adenosine-5'-O-3-thiophosphate (ATP-gamma-S) in the internal solution and there was a reduction in the NMDA effect caused by deltamethrin, a calcineurin inhibitor. Part of the NMDA induced GABAA receptor impairment was prevented by prior treatment with L-arginine. Analogously, part of the NMDA effect was prevented by blockage of NO-synthase activity by N omega-nitro-L-arginine. A combination of NO-synthase and calcineurin inhibitors completely eliminated the NMDA action. An analogous result was obtained by combining the NO-synthase inhibitor with the addition of ATP-gamma-S to the pipette medium. The additivity of the prevention of the NMDA impairment of GABAA receptor by blocking the L-arginine/NO pathway and inhibiting calcineurin activity suggests an independent involvement of these two pathways in the interaction between NMDA and the GABAA receptor. On the one hand Ca+2 influx across NMDA channels activates calcineurin and dephosphorylates the GABAA receptor complex directly or dephosphorylates proteins critical for the function of the receptor. On the other hand, Ca+2 influx activates NO-synthase and induces nitric oxide production, which regulates such receptors via protein kinase G

  4. A Special Extract of Bacopa monnieri (CDRI-08) Restores Learning and Memory by Upregulating Expression of the NMDA Receptor Subunit GluN2B in the Brain of Scopolamine-Induced Amnesic Mice

    PubMed Central

    Rai, Rakesh; Singh, Hemant K.; Prasad, S.

    2015-01-01

    In the present communication, we have investigated effects of the CDRI-08, a well characterized extract of Bacopa monnieri, on expression of the GluN2B subunit of NMDAR in various brain regions of the scopolamine-induced amnesic mice. Our behavioral data reveal that scopolamine-treated amnesic mice exhibit significant decline in the spatial memory compared to the normal control mice. Our RT-PCR and immunoblotting data revealed that the scopolamine treatment resulted in a significant downregulation of the NMDAR GluN2B subunit expression in prefrontal cortex and hippocampus. Our enzyme assay data revealed that scopolamine caused a significant increase in the acetylcholinesterase activity in both the brain regions. Further, oral administration of the CDRI-08 to scopolamine-treated amnesic mice restored the spatial memory which was found to be associated with significant upregulation of the GluN2B subunit expression and decline in the acetylcholinesterase activity in prefrontal cortex as well as hippocampus towards their levels in the normal control mice. Our study provides the evidence for the mechanism underlying role of the Bacopa monnieri extract (CDRI-08) in restoring spatial memory in amnesic mice, which may have therapeutic implications. PMID:26413117

  5. The Role of Hippocampal NMDA Receptors in Long-Term Emotional Responses following Muscarinic Receptor Activation

    PubMed Central

    Hoeller, Alexandre A.; Costa, Ana Paula R.; Bicca, Maíra A.; Matheus, Filipe C.; Lach, Gilliard; Spiga, Francesca; Lightman, Stafford L.; Walz, Roger; Collingridge, Graham L.; Bortolotto, Zuner A.; de Lima, Thereza C. M.

    2016-01-01

    Extensive evidence indicates the influence of the cholinergic system on emotional processing. Previous findings provided new insights into the underlying mechanisms of long-term anxiety, showing that rats injected with a single systemic dose of pilocarpine—a muscarinic receptor (mAChR) agonist—displayed persistent anxiogenic-like responses when evaluated in different behavioral tests and time-points (24 h up to 3 months later). Herein, we investigated whether the pilocarpine-induced long-term anxiogenesis modulates the HPA axis function and the putative involvement of NMDA receptors (NMDARs) following mAChRs activation. Accordingly, adult male Wistar rats presented anxiogenic-like behavior in the elevated plus-maze (EPM) after 24 h or 1 month of pilocarpine injection (150 mg/kg, i.p.). In these animals, mAChR activation disrupted HPA axis function inducing a long-term increase of corticosterone release associated with a reduced expression of hippocampal GRs, as well as consistently decreased NMDAR subunits expression. Furthermore, in another group of rats injected with memantine–an NMDARs antagonist (4 mg/kg, i.p.)–prior to pilocarpine, we found inhibition of anxiogenic-like behaviors in the EPM but no further alterations in the pilocarpine-induced NMDARs downregulation. Our data provide evidence that behavioral anxiogenesis induced by mAChR activation effectively yields short- and long-term alterations in hippocampal NMDARs expression associated with impairment of hippocampal inhibitory regulation of HPA axis activity. This is a novel mechanism associated with anxiety-like responses in rats, which comprise a putative target to future translational studies. PMID:26795565

  6. Control of N-methyl-D-aspartate Receptor Function by the NR2 Subunit Amino-Terminal Domain

    PubMed Central

    Yuan, Hongjie; Hansen, Kasper B.; Vance, Katie M.; Ogden, Kevin K.; Traynelis, Stephen F.

    2009-01-01

    NMDA receptors comprised of different NR2 subunits exhibit strikingly unique biophysical and pharmacological properties. Here we report that the extracellular amino-terminal domain (ATD) of the NR2 subunit controls pharmacological and kinetic properties of recombinant NMDA receptors, such as agonist potency, deactivation time course, open probability (POPEN), and mean open/shut duration. Using ATD deletion mutants of NR2A, NR2B, NR2C, NR2D and chimeras of NR2A and NR2D with interchanged ATD (NR2A-(2D-ATD) and NR2D-(2A-ATD)), we show that the ATD contributes to the low glutamate potency of NR2A-containing NMDA receptors and the high glutamate potency of NR2D-containing receptors. The ATD influences the deactivation time courses of NMDA receptors, as removal of the ATD from NR2A slows the deactivation rate, while removal of the ATD from NR2B, NR2C and NR2D accelerates the deactivation rate. Open probability also is influenced by the ATD. Removal of the ATD from NR2A or replacement of the NR2A-ATD with that of NR2D decreases POPEN in single channel recordings from outside-out patches of HEK 293 cells. By contrast, deletion of the ATD from NR2D or replacement of the NR2D ATD with that of NR2A increases POPEN and mean open duration. These data demonstrate the modular nature of NMDA receptors and show that the ATD of the different NR2 subunits plays an important role in fine-tuning the functional properties of the individual NMDA receptor subtypes. PMID:19793963

  7. Repeated ketamine administration alters N-methyl-D-aspartic acid receptor subunit gene expression: Implication of genetic vulnerability for ketamine abuse and ketamine psychosis in humans

    PubMed Central

    Xu, Ke; Lipsky, Robert H

    2015-01-01

    For more than 40 years following its approval by the Food and Drug Administration (FDA) as an anesthetic, ketamine, a non-competitive N-methyl-D-aspartic acid (NMDA) receptor antagonist, has been used as a tool of psychiatric research. As a psychedelic drug, ketamine induces psychotic symptoms, cognitive impairment, and mood elevation, which resemble some symptoms of schizophrenia. Recreational use of ketamine has been increasing in recent years. However, little is known of the underlying molecular mechanisms responsible for ketamine-associated psychosis. Recent animal studies have shown that repeated ketamine administration significantly increases NMDA receptor subunit gene expression, in particular subunit 1 (NR1 or GluN1) levels. This results in neurodegeneration, supporting a potential mechanism where up-regulation of NMDA receptors could produce cognitive deficits in chronic ketamine abuse patients. In other studies, NMDA receptor gene variants are associated with addictive behavior. Here, we focus on the roles of NMDA receptor gene subunits in ketamine abuse and ketamine psychosis and propose that full sequencing of NMDA receptor genes may help explain individual vulnerability to ketamine abuse and ketamine-associated psychosis. PMID:25245072

  8. NMDA receptors are expressed in human ovarian cancer tissues and human ovarian cancer cell lines.

    PubMed

    North, William G; Liu, Fuli; Tian, Ruiyang; Abbasi, Hamza; Akerman, Bonnie

    2015-01-01

    We have earlier demonstrated that breast cancer and small-cell lung cancer express functional NMDA receptors that can be targeted to promote cancer cell death. Human ovarian cancer tissues and human ovarian cancer cell lines (SKOV3, A2008, and A2780) have now been shown to also express NMDA-receptor subunit 1 (GluN1) and subunit 2B (GluN2B). Seventeen ovarian cancers in two arrays were screened by immunohistochemistry using polyclonal antibodies that recognize an extracellular moiety on GluN1 and on GluN2B. These specimens comprised malignant tissue with pathology diagnoses of serous papillary cystadenocarcinoma, endometrioid adenocarcinoma, and clear-cell carcinoma. Additionally, archival tissues defined as ovarian adenocarcinoma from ten patients treated at this institute were also evaluated. All of the cancerous tissues demonstrated positive staining patterns with the NMDA-receptor antibodies, while no staining was found for tumor-adjacent normal tissues or sections of normal ovarian tissue. Human ovarian adenocarcinoma cell lines (A2008, A2780, SKOV3) were demonstrated to express GluN1 by Western blotting, but displayed different levels of expression. Through immunocytochemistry utilizing GluN1 antibodies and imaging using a confocal microscope, we were able to demonstrate that GluN1 protein is expressed on the surface of these cells. In addition to these findings, GluN2B protein was demonstrated to be expressed using polyclonal antibodies against this protein. Treatment of all ovarian cell lines with antibodies against GluN1 was found to result in decreased cell viability (P<0.001), with decreases to 10%-25% that of untreated cells. Treatment of control HEK293 cells with various dilutions of GluN1 antibodies had no effect on cell viability. The GluN1 antagonist MK-801 (dizocilpine maleate) and the GluN2B antagonist ifenprodil, like antibodies, dramatically decreased the viability of A2780 ovarian tumor cells (P<0.01). Treatment of A2780 tumor xenografts with

  9. NMDA receptors are expressed in human ovarian cancer tissues and human ovarian cancer cell lines

    PubMed Central

    North, William G; Liu, Fuli; Tian, Ruiyang; Abbasi, Hamza; Akerman, Bonnie

    2015-01-01

    We have earlier demonstrated that breast cancer and small-cell lung cancer express functional NMDA receptors that can be targeted to promote cancer cell death. Human ovarian cancer tissues and human ovarian cancer cell lines (SKOV3, A2008, and A2780) have now been shown to also express NMDA-receptor subunit 1 (GluN1) and subunit 2B (GluN2B). Seventeen ovarian cancers in two arrays were screened by immunohistochemistry using polyclonal antibodies that recognize an extracellular moiety on GluN1 and on GluN2B. These specimens comprised malignant tissue with pathology diagnoses of serous papillary cystadenocarcinoma, endometrioid adenocarcinoma, and clear-cell carcinoma. Additionally, archival tissues defined as ovarian adenocarcinoma from ten patients treated at this institute were also evaluated. All of the cancerous tissues demonstrated positive staining patterns with the NMDA-receptor antibodies, while no staining was found for tumor-adjacent normal tissues or sections of normal ovarian tissue. Human ovarian adenocarcinoma cell lines (A2008, A2780, SKOV3) were demonstrated to express GluN1 by Western blotting, but displayed different levels of expression. Through immunocytochemistry utilizing GluN1 antibodies and imaging using a confocal microscope, we were able to demonstrate that GluN1 protein is expressed on the surface of these cells. In addition to these findings, GluN2B protein was demonstrated to be expressed using polyclonal antibodies against this protein. Treatment of all ovarian cell lines with antibodies against GluN1 was found to result in decreased cell viability (P<0.001), with decreases to 10%–25% that of untreated cells. Treatment of control HEK293 cells with various dilutions of GluN1 antibodies had no effect on cell viability. The GluN1 antagonist MK-801 (dizocilpine maleate) and the GluN2B antagonist ifenprodil, like antibodies, dramatically decreased the viability of A2780 ovarian tumor cells (P<0.01). Treatment of A2780 tumor xenografts with

  10. The Rac1 Inhibitor NSC23766 Suppresses CREB Signaling by Targeting NMDA Receptor Function

    PubMed Central

    Hou, Hailong; Chávez, Andrés E.; Wang, Chih-Chieh; Yang, Hongtian; Gu, Hua; Siddoway, Benjamin A.; Hall, Benjamin J.; Castillo, Pablo E.

    2014-01-01

    NMDA receptor signaling plays a complex role in CREB activation and CREB-mediated gene transcription, depending on the subcellular location of NMDA receptors, as well as how strongly they are activated. However, it is not known whether Rac1, the prototype of Rac GTPase, plays a role in neuronal CREB activation induced by NMDA receptor signaling. Here, we report that NSC23766, a widely used specific Rac1 inhibitor, inhibits basal CREB phosphorylation at S133 (pCREB) and antagonizes changes in pCREB levels induced by NMDA bath application in rat cortical neurons. Unexpectedly, we found that NSC23766 affects the levels of neuronal pCREB in a Rac1-independent manner. Instead, our results indicate that NSC23766 can directly regulate NMDA receptors as indicated by their strong effects on both exogenous and synaptically evoked NMDA receptor-mediated currents in mouse and rat neurons, respectively. Our findings strongly suggest that Rac1 does not affect pCREB signaling in cortical neurons and reveal that NSC23766 could be a novel NMDA receptor antagonist. PMID:25319697

  11. The involvement of NMDA receptors in acute and chronic effects of ethanol.

    PubMed

    Danysz, W; Dyr, W; Jankowska, E; Glazewski, S; Kostowski, W

    1992-06-01

    Recent evidence indicates involvement of excitatory amino acid receptors sensitive to N-methyl-d-aspartate (NMDA) in the action of ethanol (EtOH). Pronounced inhibition of NMDA receptor function is seen in vitro with concentrations of EtOH corresponding to those present during alcohol intoxication in humans. The present study was devoted to investigate the role of NMDA receptors in the action of EtOH in rats. Acute experiments showed antagonism by EtOH of convulsions induced by intracerebroventricular injection of NMDA. A similar effect was seen with a high dose of diazepam. Convulsions induced by an agonist of another excitatory amino acid receptor subtype, kainate, were also inhibited by EtOH. An uncompetitive antagonist of NMDA receptors, 5-methyl-10,11-dihydro-5H-dibenzocyclohepten-5,10-imine maleate (MK-801), potentiated EtOH-induced loss of righting, but attenuated the hypothermic action of EtOH. Moreover, MK-801 inhibited audiogenic convulsions in EtOH withdrawn rats. At the same time the effect of a proconvulsive dose of NMDA was not enhanced. Tolerance to the myorelaxant action of both EtOH and MK-801 upon repetitive administration was seen. Also some degree of cross-tolerance was observed. Moreover, MK-801 failed to modify EtOH preference in rats. The present results support involvement of NMDA receptors in expression of some acute and subchronic actions of EtOH and in expression of EtOH withdrawal. PMID:1385679

  12. Whole-Cell Patch-Clamp Analysis of Recombinant NMDA Receptor Pharmacology Using Brief Glutamate Applications

    PubMed Central

    Glasgow, Nathan G.; Johnson, Jon W.

    2015-01-01

    Summary NMDA receptors (NMDARs) are ionotropic glutamate receptors that are essential for synaptic plasticity, learning and memory. Dysfunction of NMDARs has been implicated in many nervous system disorders; therefore, pharmacological modulation of NMDAR activity has great therapeutic potential. However, given the broad physiological importance of NMDARs, modulating their activity often has detrimental side effects precluding pharmaceutical use of many NMDAR modulators. One approach to possibly improve the therapeutic potential of NMDAR modulators is to identify compounds that modulate subsets of NMDARs. An obvious target for modulating NMDAR subsets are the many NMDAR subtypes produced through different combinations of NMDAR subunits. With seven identified genes that encode NMDAR subunits, there are many neuronal NMDAR subtypes with distinct properties and potentially differential pharmacological sensitivities. Study of NMDAR subtype-specific pharmacology is complicated in neurons, however, because most neurons express at least three NMDAR subtypes. Thus, use of an approach that permits study in isolation of a single receptor subtype is preferred. Additionally, the effects of drugs on agonist-activated responses typically depend on duration of agonist exposure. To evaluate drug effects on synaptic transmission, an approach should be used that allows activation of receptor responses as brief as those observed during synaptic transmission, both in the absence and presence of drug. To address these issues, we designed a fast perfusion system capable of (1) delivering brief (~5 ms) and consistent applications of glutamate to recombinant NMDARs of known subunit composition, and (2) easily and quickly (~5 seconds) changing between glutamate applications in the absence and presence of drug. PMID:25023300

  13. Phosphorylation of NR2B NMDA subunits by protein kinase C in arcuate nucleus contributes to inflammatory pain in rats

    PubMed Central

    Bu, Fan; Tian, Huiyu; Gong, Shan; Zhu, Qi; Xu, Guang-Yin; Tao, Jin; Jiang, Xinghong

    2015-01-01

    The arcuate nucleus (ARC) of the hypothalamus plays a key role in pain processing. Although it is well known that inhibition of NMDA receptor (NMDAR) in ARC attenuates hyperalgesia induced by peripheral inflammation, the underlying mechanism of NMDAR activation in ARC remains unclear. Protein kinase C (PKC) is involved in several signalling cascades activated in physiological and pathological conditions. Therefore, we hypothesised that upregulation of PKC activates NMDARs in the ARC, thus contributing to inflammatory hyperalgesia. Intra-ARC injection of chelerythrine (CC), a specific PKC inhibitor, attenuated complete Freund’s adjuvant (CFA) induced thermal and mechanical hyperalgesia in a dose-dependent manner. In vivo extracellular recordings showed that microelectrophoresis of CC or MK-801 (a NMDAR antagonist) significantly reduced the enhancement of spontaneous discharges and pain-evoked discharges of ARC neurons. In addition, CFA injection greatly enhanced the expression of total and phosphorylated PKCγ in the ARC. Interestingly, CFA injection also remarkably elevated the level of phosphorylated NR2B (Tyr1472) without affecting the expression of total NR2B. Importantly, intra-ARC injection of CC reversed the upregulation of phosphorylated NR2B subunits in the ARC. Taken together, peripheral inflammation leads to an activation of NMDARs mediated by PKC activation in the ARC, thus producing thermal and mechanical hyperalgesia. PMID:26515544

  14. PDZ protein interactions underlying NMDA receptor-mediated excitotoxicity and neuroprotection by PSD-95 inhibitors.

    PubMed

    Cui, Hong; Hayashi, Amy; Sun, Hong-Shuo; Belmares, Michael P; Cobey, Carolyn; Phan, Thuymy; Schweizer, Johannes; Salter, Michael W; Wang, Yu Tian; Tasker, R Andrew; Garman, David; Rabinowitz, Joshua; Lu, Peter S; Tymianski, Michael

    2007-09-12

    In neuronal synapses, PDZ domains [postsynaptic density-95 (PSD-95)/Discs large/zona occludens-1] of PSD-95 proteins interact with C termini of NMDA receptor [NMDAR (NR)] subunits, linking them to downstream neurotoxic signaling molecules. Perturbing NMDAR/PSD-95 interactions with a Tat peptide comprising the nine C-terminal residues of the NR2B subunit (Tat-NR2B9c) reduces neurons' vulnerability to excitotoxicity and ischemia. However, NR subunit C termini may bind many of >240 cellular PDZs, any of which could mediate neurotoxic signaling independently of PSD-95. Here, we performed a proteomic and biochemical analysis of the interactions of all known human PDZs with synaptic signaling proteins including NR1, NR2A-NR2D, and neuronal nitric oxide synthase (nNOS). Tat-NR2B9c, whose interactions define PDZs involved in neurotoxic signaling, was also used. NR2A-NR2D subunits and Tat-NR2B9c had similar, highly specific, PDZ protein interactions, of which the strongest were with the PSD-95 family members (PSD-95, PSD-93, SAP97, and SAP102) and Tax interaction protein 1 (TIP1). The PSD-95 PDZ2 domain bound NR2A-NR2C subunits most strongly (EC50, approximately 1 microM), and fusing the NR2B C terminus to Tat enhanced its affinity for PSD-95 PDZ2 by >100-fold (EC50, approximately 7 nM). IC50 values for Tat-NR2B9c inhibiting NR2A-NR2C/PSD-95 interactions (approximately 1-10 microM) and nNOS/PSD-95 interactions (200 nM) confirmed the feasibility of such inhibition. To determine which of the PDZ interactions of Tat-NR2B9c mediate neuroprotection, one of PSD-95, PSD-93, SAP97, SAP102, TIP1, or nNOS expression was inhibited in cortical neurons exposed to NMDA toxicity. Only neurons lacking PSD-95 or nNOS but not PSD-93, SAP97, SAP102, or TIP1 exhibited reduced excitotoxic vulnerability. Thus, despite the ubiquitousness of PDZ domain-containing proteins, PSD-95 and nNOS above any other PDZ proteins are keys in effecting NMDAR-dependent excitotoxicity. Consequently, PSD-95

  15. Kynurenic acid amides as novel NR2B selective NMDA receptor antagonists.

    PubMed

    Borza, István; Kolok, Sándor; Galgóczy, Kornél; Gere, Anikó; Horváth, Csilla; Farkas, Sándor; Greiner, István; Domány, György

    2007-01-15

    A novel series of kynurenic acid amides, ring-enlarged derivatives of indole-2-carboxamides, was prepared and identified as in vivo active NR2B subtype selective NMDA receptor antagonists. The synthesis and SAR studies are discussed. PMID:17074483

  16. Effects of pharmacological manipulations of NMDA-receptors on deliberation in the Multiple-T task

    PubMed Central

    Blumenthal, Anna; Steiner, Adam; Seeland, Kelsey

    2011-01-01

    Both humans and non-human animals have the ability to navigate and make decisions within complex environments. This ability is largely dependent upon learning and memory processes, many of which are known to depend on NMDA-sensitive receptors. When humans come to difficult decisions they often pause to deliberate over their choices. Similarly, rats pause at difficult choice points. This behavior, known as vicarious trial and error (VTE), is hippocampally dependent and entails neurophysiological representations of expectations of future outcomes in hippocampus and downstream structures. In order to determine the dependence of VTE behaviors on NMDA-sensitive receptors, we tested rats on a Multiple-T choice task with a reward-delivery reversal known to elicit VTE. Rats under the influence of NMDA-receptor antagonists (CPP) showed a significant reduction in VTE, particularly at the reward reversal, implying a role for NMDA-sensitive receptors in the generation of vicarious trial and error behaviors. PMID:21296174

  17. Discrimination reversal conditioning of an eyeblink response is impaired by NMDA receptor blockade.

    PubMed

    Churchill, J D; Green, J T; Voss, S E; Manley, E; Steinmetz, J E; Garraghty, P E

    2001-01-01

    In the present study we examined the effects of the specific NMDA receptor antagonist CPP on discrimination reversal learning in rabbits. We report two primary findings. First, the institution of NMDA receptor blockade had no effect on a learned discrimination. Second, after stimulus reversal, CPP treatment impaired acquisition of the discrimination reversal. This impairment manifested itself early in training as a retardation in acquisition of a CR to the new CS+ and late in training as an inability to suppress responsiveness to the new CS-. Given the comparability of the present results with previously published results for phenytoin-treated rabbits, we suggest that the effects of phenytoin on learning in this paradigm is at least in part mediated by its effects on NMDA receptors. We further suggest that these findings emphasize the need to better define the role of NMDA receptor activation and hippocampally-mediated circuits in a variety of associative learning paradigms. PMID:11484997

  18. Expression of ionotropic glutamate receptors, AMPA, kainite and NMDA, in the pigeon retina.

    PubMed

    Atoji, Yasuro

    2015-07-01

    Glutamate is an excitatory neurotransmitter in the vertebrate retina. A previous study found vesicular glutamate transporter 2 (vGluT2) mRNA in the pigeon retina, suggesting that bipolar and ganglion cells are glutamatergic. The present study examined the localization of ionotropic glutamate receptors to identify receptor cells in the pigeon retina using in situ hybridization histochemistry. Nine subunits of AMPA receptor (GluA1, GluA2, GluA3, and GluA4), kainate receptor (GluK1, GluK2, and GluK4), and NMDA receptor (GluN1 and GluN2A) were found to be expressed in the inner nuclear layer (INL) and ganglion cell layers. GluA1, GluA2, GluA3, and GluA4 were primarily expressed in the inner half of INL, and the signal intensity was strong for GluA2, GluA3, and GluA4. GluK1 was intensely expressed in the outer half of INL, whereas GluK2 and GluK4 were mainly localized in the inner half of INL. GluN1 and GluN2A were moderately expressed in the inner half of INL. Horizontal cells expressed GluA3 and GluA4, and ganglion cells expressed all subunits examined. These results suggest that the glutamatergic neurotransmission in the pigeon retina is similar to that in mammals. PMID:25983186

  19. Surface expression of NMDA receptor changes during memory consolidation in the crab Neohelice granulata.

    PubMed

    Hepp, Yanil; Salles, Angeles; Carbo-Tano, Martin; Pedreira, Maria Eugenia; Freudenthal, Ramiro

    2016-08-01

    The aim of the present study was to analyze the surface expression of the NMDA-like receptors during the consolidation of contextual learning in the crab Neohelice granulata Memory storage is based on alterations in the strength of synaptic connections between neurons. The glutamatergic synapses undergo various forms of N-methyl-D aspartate receptor (NMDAR)-dependent changes in strength, a process that affects the abundance of other receptors at the synapse and underlies some forms of learning and memory. Here we propose a direct regulation of the NMDAR. Changes in NMDAR's functionality might be induced by the modification of the subunit's expression or cellular trafficking. This trafficking does not only include NMDAR's movement between synaptic and extra-synaptic localizations but also the cycling between intracellular compartments and the plasma membrane, a process called surface expression. Consolidation of contextual learning affects the surface expression of the receptor without affecting its general expression. The surface expression of the GluN1 subunit of the NMDAR is down-regulated immediately after training, up-regulated 3 h after training and returns to naïve and control levels 24 h after training. The changes in NMDAR surface expression observed in the central brain are not seen in the thoracic ganglion. A similar increment in surface expression of GluN1 in the central brain is observed 3 h after administration of the competitive GABAA receptor antagonist, bicuculline. These consolidation changes are part of a plasticity event that first, during the down-regulation, stabilizes the trace and later, at 3-h post-training, changes the threshold for synapse activation. PMID:27421895

  20. NMDA receptor mediates chronic visceral pain induced by neonatal noxious somatic stimulation

    PubMed Central

    Miranda, Adrian; Mickle, Aaron; Bruckert, Mitchell; Kannampalli, Pradeep; Banerjee, Banani; Sengupta, Jyoti N.

    2014-01-01

    NMDA receptors (NMDAR) are important in the development and maintenance of central sensitization. Our objective was to investigate the role of spinal neurons and NMDAR in the maintenance of chronic visceral pain. Neonatal rats were injected with acidic saline adjusted to pH4.0 in the gastrocnemius muscle every other day for 12 days. In adult rats, NR1 and NR2B subunits were examined in the lumbo-sacral (LS) spinal cord. A baseline, visceromotor response (VMR) to graded colorectal distension (CRD) was recorded before and after administration of the NMDA antagonist, CGS-19755. Extracellular recordings were performed from CRD-sensitive LS spinal neurons and pelvic nerve afferents (PNA) before and after CGS-19755. Rats that received pH 4.0 saline injections demonstrated a significant increase in the expression NR2B subunits and VMR response to CRD >20mmHg. CGS-19755 (i.v. or i.t.) had no effect in naïve rats, but significantly decreased the response to CRD in pH4.0 saline injected rats. CGS-19755 had no effect on the spontaneous firing of SL-A, but decreased that of SL-S. Similarly, CGS-19755 attenuates the responses of SL-S neurons to CRD, but had no effect on SL-A neurons or on the response characteristics of PNA fibers. Neonatal noxious somatic stimulation results in chronic visceral hyperalgesia and sensitizes a specific subpopulation of CRD-sensitive spinal neurons. The sensitization of these SL-S spinal neurons is attenuated by the NMDAR antagonist. The results of this study suggest that spinal NMDARs play an important role in the development of hyperalgesia early in life. PMID:25281204

  1. Dopamine D1 receptor inhibition of NMDA receptor currents mediated by tyrosine kinase-dependent receptor trafficking in neonatal rat striatum

    PubMed Central

    Tong, Huaxia; Gibb, Alasdair J

    2008-01-01

    NMDA receptors are of particular importance in the control of synaptic strength and integration of synaptic activity. Dopamine receptor modulation of NMDA receptors in neonatal striatum may influence the efficacy of synaptic transmission in the cortico-striatal pathway and if so, this modulation will affect the behaviour of the basal ganglia network. Here, we show that in acute brain slices of neonatal (P7) rat striatum the dopamine D1 receptor agonist SKF-82958 significantly decreases NMDA receptor currents in patch-clamp whole-cell recordings. This inhibition is not abolished by application of a G protein inhibitor (GDP-β-S) or irreversible G protein activator (GTP-γ-S) suggesting a G protein-independent mechanism. In addition, intracellular application of protein tyrosine kinase inhibitors (lavendustin A or PP2) abolished D1 inhibition of NMDA currents. In contrast, in older animals (P28) D1 receptor activation produces a potentiation of the NMDA response which suggests there is a developmental switch in D1 modulation of striatal NMDA receptors. Single-channel recordings show that direct D1 receptor inhibition of NMDA receptors cannot be observed in isolated membrane patches. We hypothesize that D1 inhibition in whole-cell recordings from neonatal rats may be mediated by a change in NMDA receptor trafficking. Consistent with this hypothesis, intracellular application of a dynamin inhibitory peptide (QVPSRPNRAP) abolished D1 inhibition of NMDA receptor currents. We therefore conclude that a tyrosine kinase-dependent alteration of NMDA receptor trafficking underlies D1 dopamine receptor-mediated down-regulation of NMDA receptor currents in medium spiny neurons of neonatal rat striatum. PMID:18703578

  2. In vitro neuronal network activity in NMDA receptor encephalitis

    PubMed Central

    2013-01-01

    Background Anti-NMDA-encephalitis is caused by antibodies against the N-methyl-D-aspartate receptor (NMDAR) and characterized by a severe encephalopathy with psychosis, epileptic seizures and autonomic disturbances. It predominantly occurs in young women and is associated in 59% with an ovarian teratoma. Results We describe effects of cerebrospinal fluid (CSF) from an anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis patient on in vitro neuronal network activity (ivNNA). In vitro NNA of dissociated primary rat cortical populations was recorded by the microelectrode array (MEA) system. The 23-year old patient was severely affected but showed an excellent recovery following multimodal immunomodulatory therapy and removal of an ovarian teratoma. Patient CSF (pCSF) taken during the initial weeks after disease onset suppressed global spike- and burst rates of ivNNA in contrast to pCSF sampled after clinical recovery and decrease of NMDAR antibody titers. The synchrony of pCSF-affected ivNNA remained unaltered during the course of the disease. Conclusion Patient CSF directly suppresses global activity of neuronal networks recorded by the MEA system. In contrast, pCSF did not regulate the synchrony of ivNNA suggesting that NMDAR antibodies selectively regulate distinct parameters of ivNNA while sparing their functional connectivity. Thus, assessing ivNNA could represent a new technique to evaluate functional consequences of autoimmune encephalitis-related CSF changes. PMID:23379293

  3. NMDA receptor hypofunction produces concomitant firing rate potentiation and burst activity reduction in the prefrontal cortex

    PubMed Central

    Jackson, Mark E.; Homayoun, Houman; Moghaddam, Bita

    2004-01-01

    Cognitive deficits associated with frontal lobe dysfunction are a determinant of long-term disability in schizophrenia and are not effectively treated with available medications. Clinical studies show that many aspects of these deficits are transiently induced in healthy individuals treated with N-methyl-d-aspartate (NMDA) antagonists. These findings and recent genetic linkage studies strongly implicate NMDA receptor deficiency in schizophrenia and suggest that reversing this deficiency is pertinent to treating the cognitive symptoms of schizophrenia. Despite the wealth of behavioral data on the effects of NMDA antagonist treatment in humans and laboratory animals, there is a fundamental lack of understanding about the mechanisms by which a general state of NMDA deficiency influences the function of cortical neurons. Using ensemble recording in freely moving rats, we found that NMDA antagonist treatment, at doses that impaired working memory, potentiated the firing rate of most prefrontal cortex neurons. This potentiation, which correlated with expression of behavioral stereotypy, resulted from an increased number of irregularly discharged single spikes. Concurrent with the increase in spike activity, there was a significant reduction in organized bursting activity. These results identify two distinct mechanisms by which NMDA receptor deficiency may disrupt frontal lobe function: an increase in disorganized spike activity, which may enhance cortical noise and transmission of disinformation; and a decrease in burst activity, which reduces transmission efficacy of cortical neurons. These findings provide a physiological basis for the NMDA receptor deficiency model of schizophrenia and may clarify the nature of cortical dysfunction in this disease. PMID:15159546

  4. NMDA receptors are upregulated and trafficked to the plasma membrane after sigma-1 receptor activation in the rat hippocampus.

    PubMed

    Pabba, Mohan; Wong, Adrian Y C; Ahlskog, Nina; Hristova, Elitza; Biscaro, Dante; Nassrallah, Wissam; Ngsee, Johnny K; Snyder, Melissa; Beique, Jean-Claude; Bergeron, Richard

    2014-08-20

    Sigma-1 receptors (σ-1Rs) are endoplasmic reticulum resident chaperone proteins implicated in many physiological and pathological processes in the CNS. A striking feature of σ-1Rs is their ability to interact and modulate a large number of voltage- and ligand-gated ion channels at the plasma membrane. We have reported previously that agonists for σ-1Rs potentiate NMDA receptor (NMDAR) currents, although the mechanism by which this occurs is still unclear. In this study, we show that in vivo administration of the selective σ-1R agonists (+)-SKF 10,047 [2S-(2α,6α,11R*]-1,2,3,4,5,6-hexahydro-6,11-dimethyl-3-(2-propenyl)-2,6-methano-3-benzazocin-8-ol hydrochloride (N-allylnormetazocine) hydrochloride], PRE-084 (2-morpholin-4-ylethyl 1-phenylcyclohexane-1-carboxylate hydrochloride), and (+)-pentazocine increases the expression of GluN2A and GluN2B subunits, as well as postsynaptic density protein 95 in the rat hippocampus. We also demonstrate that σ-1R activation leads to an increased interaction between GluN2 subunits and σ-1Rs and mediates trafficking of NMDARs to the cell surface. These results suggest that σ-1R may play an important role in NMDAR-mediated functions, such as learning and memory. It also opens new avenues for additional studies into a multitude of pathological conditions in which NMDARs are involved, including schizophrenia, dementia, and stroke. PMID:25143613

  5. Integrative role for serotonergic and glutamatergic receptor mechanisms in the action of NMDA antagonists: potential relationships to antipsychotic drug actions on NMDA antagonist responsiveness.

    PubMed

    Breese, George R; Knapp, Darin J; Moy, Sheryl S

    2002-06-01

    NMDA receptor antagonists worsen symptoms in schizophrenia and induce schizophrenic-like symptoms in normal individuals. In animals, NMDA antagonist-induced behavioral responses include increased activity, head weaving, deficits in paired pulse inhibition and social interaction, and increased forced swim immobility. Repeated exposure to NMDA antagonists in animals results in behavioral sensitization-a phenomenon accentuated in rats with dopaminergic neurons lesioned during development. In keeping with an involvement of serotonin and glutamate release in NMDA antagonist action, selected behaviors induced by NMDA antagonists are minimized by 5-HT(2A) receptor antagonists and mGLU2 receptor agonists. These observations provide promising new approaches for treating acute NMDA antagonist-induced psychosis. Further, acute atypical antipsychotic drugs also minimize NMDA antagonist actions to a greater degree than typical antipsychotics. However, because knowledge concerning acute versus chronic effectiveness of various antipsychotic drugs against NMDA antagonist neuropathology is limited, future studies to define more fully the basis of their differences in efficacy after chronic treatment could provide an understanding of their actions on neural mechanisms responsible for the core pathogenesis of schizophrenia. PMID:12204191

  6. Contribution of Primary Afferent Input to Trigeminal Astroglial Hyperactivity, Cytokine Induction and NMDA Receptor Phosphorylation.

    PubMed

    Wang, H; Guo, W; Yang, K; Wei, F; Dubner, R; Ren, K

    2010-03-01

    We tested the hypothesis that primary afferent inputs play a role in astroglial hyperactivity after tissue injury. We first injected complete Freund's adjuvant (CFA, 0.05 ml, 1:1 oil/saline) into the masseter muscle, which upregulated glial fibrillary acidic protein (GFAP), a marker of astrocytes, interleukin (IL)-1β an inflammatory cytokine, and phosphorylation of serine896 of the NR1 subunit (P-NR1) of the NMDA receptor in the subnuclei interpolaris/caudalis (Vi/Vc) transition zone, an important structure for processing trigeminal nociceptive input. Local anesthetic block with lidocaine (2%) of the masseter muscle at 10 min prior to injection of CFA into the same site significantly reduced the CFA-induced increase in GFAP, IL-1β and P-NR1 (p<0.05, n=4/group). We then tested the effect of peripheral electrical stimulation (ES). The ES protocol was burst stimulation consisting of trains of 4 square pulses (10-100 Hz, 0.1-3 mA, 0.5 ms pulse width). Under pentobarbital anesthesia, an ES was delivered every 0.2 s for a total of 30 min. The Vi/Vc tissues were processed for immunohistochemistry or western blot analysis at 10-120 min after ES. Compared to naive and SHAM-treated rats, there was increased immunoreactivity against GFAP, IL-1β and P-NR1 in the Vi/Vc in rats receiving ES. Double staining showed that IL-1β was selectively localized in GFAP-positive astroglia, and P-NR1-immunoreactivity was localized to neurons. These findings indicate that primary afferent inputs are necessary and sufficient to induce astroglial hyperactivity and upregulation of IL-1β, as well as neuronal NMDA receptor phosphorylation. PMID:21170295

  7. Activity-dependent mRNA splicing controls ER export and synaptic delivery of NMDA receptors.

    PubMed

    Mu, Yuanyue; Otsuka, Takeshi; Horton, April C; Scott, Derek B; Ehlers, Michael D

    2003-10-30

    Activity-dependent targeting of NMDA receptors (NMDARs) is a key feature of synapse formation and plasticity. Although mechanisms for rapid trafficking of glutamate receptors have been identified, the molecular events underlying chronic accumulation or loss of synaptic NMDARs have remained unclear. Here we demonstrate that activity controls NMDAR synaptic accumulation by regulating forward trafficking at the endoplasmic reticulum (ER). ER export is accelerated by the alternatively spliced C2' domain of the NR1 subunit and slowed by the C2 splice cassette. This mRNA splicing event at the C2/C2' site is activity dependent, with C2' variants predominating upon activity blockade and C2 variants abundant with increased activity. The switch to C2' accelerates NMDAR forward trafficking by enhancing recruitment of nascent NMDARs to ER exit sites via binding of a divaline motif within C2' to COPII coats. These results define a novel pathway underlying activity-dependent targeting of glutamate receptors, providing an unexpected mechanistic link between activity, mRNA splicing, and membrane trafficking during excitatory synapse modification. PMID:14642281

  8. Interaction between positive allosteric modulators and trapping blockers of the NMDA receptor channel

    PubMed Central

    Emnett, Christine M; Eisenman, Lawrence N; Mohan, Jayaram; Taylor, Amanda A; Doherty, James J; Paul, Steven M; Zorumski, Charles F; Mennerick, Steven

    2015-01-01

    Background and Purpose Memantine and ketamine are clinically used, open-channel blockers of NMDA receptors exhibiting remarkable pharmacodynamic similarities despite strikingly different clinical profiles. Although NMDA channel gating constitutes an important difference between memantine and ketamine, it is unclear how positive allosteric modulators (PAMs) might affect the pharmacodynamics of these NMDA blockers. Experimental Approach We used two different PAMs: SGE-201, an analogue of an endogenous oxysterol, 24S-hydroxycholesterol, along with pregnenolone sulphate (PS), to test on memantine and ketamine responses in single cells (oocytes and cultured neurons) and networks (hippocampal slices), using standard electrophysiological techniques. Key Results SGE-201 and PS had no effect on steady-state block or voltage dependence of a channel blocker. However, both PAMs increased the actions of memantine and ketamine on phasic excitatory post-synaptic currents, but neither revealed underlying pharmacodynamic differences. SGE-201 accelerated the re-equilibration of blockers during voltage jumps. SGE-201 also unmasked differences among the blockers in neuronal networks – measured either by suppression of activity in multi-electrode arrays or by neuroprotection against a mild excitotoxic insult. Either potentiating NMDA receptors while maintaining the basal activity level or increasing activity/depolarization without potentiating NMDA receptor function is sufficient to expose pharmacodynamic blocker differences in suppressing network function and in neuroprotection. Conclusions and Implications Positive modulation revealed no pharmacodynamic differences between NMDA receptor blockers at a constant voltage, but did expose differences during spontaneous network activity. Endogenous modulator tone of NMDA receptors in different brain regions may underlie differences in the effects of NMDA receptor blockers on behaviour. PMID:25377730

  9. Acute liver failure-induced death of rats is delayed or prevented by blocking NMDA receptors in brain.

    PubMed

    Cauli, Omar; Rodrigo, Regina; Boix, Jordi; Piedrafita, Blanca; Agusti, Ana; Felipo, Vicente

    2008-09-01

    Developing procedures to delay the mechanisms of acute liver failure-induced death would increase patients' survival by allowing time for liver regeneration or to receive a liver for transplantation. Hyperammonemia is a main contributor to brain herniation and mortality in acute liver failure (ALF). Acute ammonia intoxication in rats leads to N-methyl-D-aspartate (NMDA) receptor activation in brain. Blocking these receptors prevents ammonia-induced death. Ammonia-induced activation of NMDA receptors could contribute to ALF-induced death. If this were the case, blocking NMDA receptors could prevent or delay ALF-induced death. The aim of this work was to assess 1) whether ALF leads to NMDA receptors activation in brain in vivo and 2) whether blocking NMDA receptors prevents or delays ALF-induced death of rats. It is shown, by in vivo brain microdialysis, that galactosamine-induced ALF leads to NMDA receptors activation in brain. Blocking NMDA receptors by continuous administration of MK-801 or memantine through miniosmotic pumps affords significant protection against ALF-induced death, increasing the survival time approximately twofold. Also, when liver injury is not 100% lethal (1.5 g/kg galactosamine), blocking NMDA receptors increases the survival rate from 23 to 62%. This supports that blocking NMDA receptors could have therapeutic utility to improve survival of patients with ALF. PMID:18599589

  10. Activation of type 5 metabotropic glutamate receptors attenuates deficits in cognitive flexibility induced by NMDA receptor blockade

    PubMed Central

    Stefani, Mark R.; Moghaddam, Bita

    2010-01-01

    Metabotropic glutamate (mGlu) receptors provide a mechanism by which the function of NMDA glutamate receptors can be modulated. As NMDA receptor hypofunction is implicated in the etiology of psychiatric disorders, including schizophrenia, the pharmacological regulation of mGlu receptor activity represents a promising therapeutic approach. We examined the effects of the positive allosteric mGlu5 receptor modulator 3- cyano-N-(1,3-diphenyl-1H-pyrazol-5-yl)benzamide (CDPPB), alone and in combination with the NMDA receptor antagonist MK-801, on a task measuring cognitive set-shifting ability. This task measures NMDA receptor-dependent cognitive abilities analogous to those impaired in schizophrenia. Systemic administration of CDPPB (10 & 30 mg/kg i.p) blocked MK-801 (0.1 mg/kg, i.p.)-induced impairments in set-shifting ability. The effect on learning was dose-dependent, with the 30 mg/kg dose having a greater effect than the 10 mg/kg dose across all trials. This ameliorative effect of CDPPB reflected a reduction in MK-801-induced perseverative responding. These results add to the evidence that mGlu5 receptors interact functionally with NMDA receptors to regulate behavior, and suggest that positive modulators of mGlu5 receptors may have therapeutic potential in the treatment of disorders, like schizophrenia, characterized by impairments in cognitive flexibility and memory. PMID:20371234

  11. NMDA receptor antibodies associated with distinct white matter syndromes

    PubMed Central

    Hacohen, Yael; Absoud, Michael; Hemingway, Cheryl; Jacobson, Leslie; Lin, Jean-Pierre; Pike, Mike; Pullaperuma, Sunil; Siddiqui, Ata; Wassmer, Evangeline; Waters, Patrick; Irani, Sarosh R.; Buckley, Camilla

    2014-01-01

    Objective: To report the clinical and radiologic findings of children with NMDA receptor (NMDAR) antibodies and white matter disorders. Method: Ten children with significant white matter involvement, with or without anti-NMDAR encephalitis, were identified from 46 consecutive NMDAR antibody–positive pediatric patients. Clinical and neuroimaging features were reviewed and the treatment and outcomes of the neurologic syndromes evaluated. Results: Three distinct clinicoradiologic phenotypes were recognized: brainstem encephalitis (n = 3), leukoencephalopathy following herpes simplex virus encephalitis (HSVE) (n = 2), and acquired demyelination syndromes (ADS) (n = 5); 3 of the 5 with ADS had myelin oligodendrocyte glycoprotein as well as NMDAR antibodies. Typical NMDAR antibody encephalitis was seen in 3 patients remote from the first neurologic syndrome (2 brainstem, 1 post-HSVE). Six of the 7 patients (85%) who were treated acutely, during the original presentation with white matter involvement, improved following immunotherapy with steroids, IV immunoglobulin, and plasma exchange, either individually or in combination. Two patients had escalation of immunotherapy at relapse resulting in clinical improvement. The time course of clinical features, treatments, and recoveries correlated broadly with available serum antibody titers. Conclusion: Clinicoradiologic evidence of white matter involvement, often distinct, was identified in 22% of children with NMDAR antibodies and appears immunotherapy responsive, particularly when treated in the acute phase of neurologic presentation. When observed, this clinical improvement is often mirrored by reduction in NMDAR antibody levels, suggesting that these antibodies may mediate the white matter disease. PMID:25340058

  12. NMDA Receptor Involvement in Spatial Delayed Alternation in Developing Rats

    PubMed Central

    Watson, Deborah J.; Herbert, Mariel R.; Stanton, Mark E.

    2014-01-01

    Two experiments examined the effect of the non-competitive NMDA receptor antagonist, dizocilpine maleate (MK-801), on spatial working memory during development. Rats were trained on spatial delayed alternation (SDA) in a T-maze following i.p. administration of 0.06 mg/kg MK-801, 0.1 mg/kg MK-801, or saline on postnatal days (P) P23 and P33 (Experiment 1), or following bilateral intrahippocampal administration of 2.5 or 5.0 micro-g per side MK-801 or saline on P26 (Experiment 2). In Experiment 1, MK-801 dose-dependently impaired SDA learning at both ages. Because the same doses of systemic MK-801 have no effect on T-maze position discrimination learning, impairment of SDA by MK-801 likely reflects disruption of spatial working memory. Both doses of MK-801 abolished acquisition of SDA performance in Experiment 2. Disruption of hippocampal plasticity may account for the effects produced by systemic MK-801 administration. These results confirm and extend earlier lesion studies by implicating plasticity of hippocampal neurons in the ontogeny of spatial delayed alternation. PMID:19170429

  13. Differential reelin-induced enhancement of NMDA and AMPA receptor activity in the adult hippocampus.

    PubMed

    Qiu, Shenfeng; Zhao, Lisa F; Korwek, Kimberly M; Weeber, Edwin J

    2006-12-13

    The developmental lamination of the hippocampus and other cortical structures requires a signaling cascade initiated by reelin and its receptors, apoER2 (apolipoprotein E receptor 2) and VLDLR (very-low-density lipoprotein receptor). However, the functional significance of continued reelin expression in the postnatal brain remains poorly understood. Here, we show that reelin application to adult mice hippocampal slices leads to enhanced glutamatergic transmission mediated by NMDA receptors (NMDARs) and AMPA receptors (AMPARs) through distinct mechanisms. Application of recombinant reelin enhanced NMDAR-mediated currents through postsynaptic mechanisms, as revealed by the variance-mean analysis of synaptic NMDAR currents, assessment of spontaneous miniature events, and the levels of NMDAR subunits at synaptic surface. In comparison, nonstationary fluctuation analysis of miniature AMPAR currents and quantification of synaptic surface proteins revealed that reelin-induced enhancement of AMPAR responses was mediated by increased AMPAR numbers. Reelin enhancement of synaptic NMDAR currents was abolished when receptor-associated protein (RAP) or the Src inhibitor 4-amino-5-(4-methylphenyl)-7-(t-butyl)pyrazolo[3,4-d]-pyrimidine (PP1) was bath applied and was abrogated by including PP1 in the recording electrodes. In comparison, including RAP or an inactive PP1 analog PP3 in the recording electrode was without effect. Interestingly, the increased AMPAR response after reelin application was not blocked by PP1 but was blocked by the phosphoinositide-3' kinase (PI3K) inhibitors wortmannin and LY294002 [2-(4-morpholinyl)-8-phenyl-1(4H)-benzopyran-4-one hydrochloride]. Furthermore, reelin-induced, PI3K-dependent AMPAR surface insertion was also observed in cultured hippocampal neurons. Together, these results reveal a differential functional coupling of reelin signaling with NMDAR and AMPAR function and define a novel mechanism for controlling synaptic strength and plasticity

  14. Neuroendothelial NMDA receptors as therapeutic targets in experimental autoimmune encephalomyelitis.

    PubMed

    Macrez, Richard; Ortega, Maria C; Bardou, Isabelle; Mehra, Anupriya; Fournier, Antoine; Van der Pol, Susanne M A; Haelewyn, Benoit; Maubert, Eric; Lesept, Flavie; Chevilley, Arnaud; de Castro, Fernando; De Vries, Helga E; Vivien, Denis; Clemente, Diego; Docagne, Fabian

    2016-09-01

    Multiple sclerosis is among the most common causes of neurological disability in young adults. Here we provide the preclinical proof of concept of the benefit of a novel strategy of treatment for multiple sclerosis targeting neuroendothelial N-methyl-D-aspartate glutamate receptors. We designed a monoclonal antibody against N-methyl-D-aspartate receptors, which targets a regulatory site of the GluN1 subunit of N-methyl-D-aspartate receptor sensitive to the protease tissue plasminogen activator. This antibody reverted the effect of tissue plasminogen activator on N-methyl-D-aspartate receptor function without affecting basal N-methyl-D-aspartate receptor activity (n = 21, P < 0.01). This antibody bound N-methyl-D-aspartate receptors on the luminal surface of neurovascular endothelium in human tissues and in mouse, at the vicinity of tight junctions of the blood-spinal cord barrier. Noteworthy, it reduced human leucocyte transmigration in an in vitro model of the blood-brain barrier (n = 12, P < 0.05). When injected during the effector phase of MOG-induced experimental autoimmune encephalomyelitis (n = 24), it blocked the progression of neurological impairments, reducing cumulative clinical score (P < 0.001) and mean peak score (P < 0.001). This effect was observed in wild-type animals but not in tissue plasminogen activator knock-out animals (n = 10). This therapeutic effect was associated to a preservation of the blood-spinal cord barrier (n = 6, P < 0.001), leading to reduced leucocyte infiltration (n = 6, P < 0.001). Overall, this study unveils a critical function of endothelial N-methyl-D-aspartate receptor in multiple sclerosis, and highlights the therapeutic potential of strategies targeting the protease-regulated site of N-methyl-D-aspartate receptor. PMID:27435092

  15. Presynaptic c-Jun N-terminal Kinase 2 regulates NMDA receptor-dependent glutamate release

    PubMed Central

    Nisticò, Robert; Florenzano, Fulvio; Mango, Dalila; Ferraina, Caterina; Grilli, Massimo; Di Prisco, Silvia; Nobili, Annalisa; Saccucci, Stefania; D'Amelio, Marcello; Morbin, Michela; Marchi, Mario; Mercuri, Nicola B.; Davis, Roger J.; Pittaluga, Anna; Feligioni, Marco

    2015-01-01

    Activation of c-Jun N-terminal kinase (JNK) signaling pathway is a critical step for neuronal death occurring in several neurological conditions. JNKs can be activated via receptor tyrosine kinases, cytokine receptors, G-protein coupled receptors and ligand-gated ion channels, including the NMDA glutamate receptors. While JNK has been generally associated with postsynaptic NMDA receptors, its presynaptic role remains largely unexplored. Here, by means of biochemical, morphological and functional approaches, we demonstrate that JNK and its scaffold protein JIP1 are also expressed at the presynaptic level and that the NMDA-evoked glutamate release is controlled by presynaptic JNK-JIP1 interaction. Moreover, using knockout mice for single JNK isoforms, we proved that JNK2 is the essential isoform in mediating this presynaptic event. Overall the present findings unveil a novel JNK2 localization and function, which is likely to play a role in different physiological and pathological conditions. PMID:25762148

  16. Stargazin is an AMPA receptor auxiliary subunit.

    PubMed

    Vandenberghe, Wim; Nicoll, Roger A; Bredt, David S

    2005-01-11

    AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) receptors mediate fast excitatory synaptic transmission in brain and underlie aspects of synaptic plasticity. Numerous AMPA receptor-binding proteins have been implicated in AMPA receptor trafficking and anchoring. However, the relative contributions of these proteins to the composition of native AMPA receptor complexes in brain remain uncertain. Here, we use blue native gel electrophoresis to analyze the composition of native AMPA receptor complexes in cerebellar extracts. We identify two receptor populations: a functional form that contains the transmembrane AMPA receptor-regulatory protein stargazin and an apo-form that lacks stargazin. Limited proteolysis confirms assembly of stargazin with a large proportion of native AMPA receptors. In contrast, other AMPA receptor-interacting proteins, such as synapse-associated protein 97, glutamate receptor-interacting protein 1, protein kinase Calpha binding protein, N-ethylmaleimide-sensitive fusion protein, AP2, and protein 4.1N, do not show significant association with AMPA receptor complexes on native gels. These data identify stargazin as an auxiliary subunit for a neurotransmitter-gated ion channel. PMID:15630087

  17. Cell type-specific pharmacology of NMDA receptors using masked MK801

    PubMed Central

    Yang, Yunlei; Lee, Peter; Sternson, Scott M

    2015-01-01

    N-Methyl-D-aspartate receptors (NMDA-Rs) are ion channels that are important for synaptic plasticity, which is involved in learning and drug addiction. We show enzymatic targeting of an NMDA-R antagonist, MK801, to a molecularly defined neuronal population with the cell-type-selectivity of genetic methods and the temporal control of pharmacology. We find that NMDA-Rs on dopamine neurons are necessary for cocaine-induced synaptic potentiation, demonstrating that cell type-specific pharmacology can be used to dissect signaling pathways within complex brain circuits. DOI: http://dx.doi.org/10.7554/eLife.10206.001 PMID:26359633

  18. Principal role of NR3 subunits in NR1/NR3 excitatory glycine receptor function.

    PubMed

    Madry, Christian; Mesic, Ivana; Bartholomäus, Ingo; Nicke, Annette; Betz, Heinrich; Laube, Bodo

    2007-03-01

    Calcium-permeable N-methyl-d-aspartate (NMDA) receptors are tetrameric cation channels composed of glycine-binding NR1 and glutamate-binding NR2 subunits, which require binding of both glutamate and glycine for efficient channel gating. In contrast, receptors assembled from NR1 and NR3 subunits function as calcium-impermeable excitatory glycine receptors that respond to agonist application only with low efficacy. Here, we show that antagonists of and substitutions within the glycine-binding site of NR1 potentiate NR1/NR3 receptor function up to 25-fold, but inhibition or mutation of the NR3 glycine binding site reduces or abolishes receptor activation. Thus, glycine bound to the NR1 subunit causes auto-inhibition of NR1/NR3 receptors whereas glycine binding to the NR3 subunits is required for opening of the ion channel. Our results establish differential roles of the high-affinity NR3 and low-affinity NR1 glycine-binding sites in excitatory glycine receptor function. PMID:17214961

  19. Inhibition of in vivo [(3)H]MK-801 binding by NMDA receptor open channel blockers and GluN2B antagonists in rats and mice.

    PubMed

    Fernandes, Alda; Wojcik, Trevor; Baireddy, Praveena; Pieschl, Rick; Newton, Amy; Tian, Yuan; Hong, Yang; Bristow, Linda; Li, Yu-Wen

    2015-11-01

    N-methyl-D-aspartate (NMDA) receptor antagonists, including open channel blockers and GluN2B receptor subtype selective antagonists, have been developed for the treatment of depression. The current study investigated effects of systemically administered NMDA channel blockers and GluN2B receptor antagonists on NMDA receptor activity in rodents using in vivo [(3)H]MK-801 binding. The receptor occupancy of GluN2B antagonists was measured using ex vivo [(3)H]Ro 25-6981 binding. Ketamine, a NMDA receptor channel blocker, produced a dose/exposure- and time-dependent inhibition of in vivo [(3)H]MK-801 binding that was maximal at ~100%. The complete inhibition of in vivo [(3)H]MK-801 binding was also observed with NMDA receptor channel blockers, AZD6765 (Lanicemine) and MK-801 (Dizocilpine). CP-101,606 (Traxoprodil), a GluN2B antagonist, produced a dose/exposure- and time-dependent inhibition of in vivo [(3)H]MK-801 binding that was maximal at ~60%. Partial inhibition was also observed with other GluN2B antagonists including MK-0657 (CERC-301), EVT-101, Ro 25-6981 and radiprodil. For all GluN2B antagonists tested, partial [(3)H]MK-801 binding inhibition was achieved at doses saturating GluN2B receptor occupancy. Combined treatment with ketamine (10mg/kg, i.p.) and Ro 25-6981(10mg/kg, i.p.) produced a level of inhibition of in vivo [(3)H]MK-801 binding that was similar to treatment with either agent alone. In conclusion, this in vivo [(3)H]MK-801 binding study shows that NMDA receptor activity in the rodent forebrain can be inhibited completely by channel blockers, but only partially (~60%) by GluN2B receptor antagonists. At doses effective in preclinical models of depression, ketamine may preferentially inhibit the same population of NMDA receptors as Ro 25-6981, namely those containing the GluN2B subunit. PMID:26325093

  20. Key Amino Acid Residues within the Third Membrane Domains of NR1 and NR2 Subunits Contribute to the Regulation of the Surface Delivery of N-methyl-d-aspartate Receptors*

    PubMed Central

    Kaniakova, Martina; Krausova, Barbora; Vyklicky, Vojtech; Korinek, Miloslav; Lichnerova, Katarina; Vyklicky, Ladislav; Horak, Martin

    2012-01-01

    N-methyl-d-aspartate (NMDA) receptors are glutamate ionotropic receptors that play critical roles in synaptic transmission, plasticity, and excitotoxicity. The functional NMDA receptors, heterotetramers composed mainly of two NR1 and two NR2 subunits, likely pass endoplasmic reticulum quality control before they are released from the endoplasmic reticulum and trafficked to the cell surface. However, the mechanism underlying this process is not clear. Using truncated and mutated NMDA receptor subunits expressed in heterologous cells, we found that the M3 domains of both NR1 and NR2 subunits contain key amino acid residues that contribute to the regulation of the number of surface functional NMDA receptors. These key residues are critical neither for the interaction between the NR1 and NR2 subunits nor for the formation of the functional receptors, but rather they regulate the early trafficking of the receptors. We also found that the identified key amino acid residues within both NR1 and NR2 M3 domains contribute to the regulation of the surface expression of unassembled NR1 and NR2 subunits. Thus, our data identify the unique role of the membrane domains in the regulation of the number of surface NMDA receptors. PMID:22711533

  1. Synaptic and extrasynaptic NMDA receptors are gated by different endogenous coagonists.

    PubMed

    Papouin, Thomas; Ladépêche, Laurent; Ruel, Jérôme; Sacchi, Silvia; Labasque, Marilyne; Hanini, Marwa; Groc, Laurent; Pollegioni, Loredano; Mothet, Jean-Pierre; Oliet, Stéphane H R

    2012-08-01

    N-methyl-d-aspartate receptors (NMDARs) are located in neuronal cell membranes at synaptic and extrasynaptic locations, where they are believed to mediate distinct physiological and pathological processes. Activation of NMDARs requires glutamate and a coagonist whose nature and impact on NMDAR physiology remain elusive. We report that synaptic and extrasynaptic NMDARs are gated by different endogenous coagonists, d-serine and glycine, respectively. The regionalized availability of the coagonists matches the preferential affinity of synaptic NMDARs for d-serine and extrasynaptic NMDARs for glycine. Furthermore, glycine and d-serine inhibit NMDAR surface trafficking in a subunit-dependent manner, which is likely to influence NMDARs subcellular location. Taking advantage of this coagonist segregation, we demonstrate that long-term potentiation and NMDA-induced neurotoxicity rely on synaptic NMDARs only. Conversely, long-term depression requires both synaptic and extrasynaptic receptors. Our observations provide key insights into the operating mode of NMDARs, emphasizing functional distinctions between synaptic and extrasynaptic NMDARs in brain physiology. PMID:22863013

  2. Glycine activated ion channel subunits encoded by ctenophore glutamate receptor genes

    PubMed Central

    Alberstein, Robert; Grey, Richard; Zimmet, Austin; Simmons, David K.; Mayer, Mark L.

    2015-01-01

    Recent genome projects for ctenophores have revealed the presence of numerous ionotropic glutamate receptors (iGluRs) in Mnemiopsis leidyi and Pleurobrachia bachei, among our earliest metazoan ancestors. Sequence alignments and phylogenetic analysis show that these form a distinct clade from the well-characterized AMPA, kainate, and NMDA iGluR subtypes found in vertebrates. Although annotated as glutamate and kainate receptors, crystal structures of the ML032222a and PbiGluR3 ligand-binding domains (LBDs) reveal endogenous glycine in the binding pocket, whereas ligand-binding assays show that glycine binds with nanomolar affinity; biochemical assays and structural analysis establish that glutamate is occluded from the binding cavity. Further analysis reveals ctenophore-specific features, such as an interdomain Arg-Glu salt bridge, present only in subunits that bind glycine, but also a conserved disulfide in loop 1 of the LBD that is found in all vertebrate NMDA but not AMPA or kainate receptors. We hypothesize that ctenophore iGluRs are related to an early ancestor of NMDA receptors, suggesting a common evolutionary path for ctenophores and bilaterian species, and suggest that future work should consider both glycine and glutamate as candidate neurotransmitters in ctenophore species. PMID:26460032

  3. Glycine activated ion channel subunits encoded by ctenophore glutamate receptor genes.

    PubMed

    Alberstein, Robert; Grey, Richard; Zimmet, Austin; Simmons, David K; Mayer, Mark L

    2015-11-01

    Recent genome projects for ctenophores have revealed the presence of numerous ionotropic glutamate receptors (iGluRs) in Mnemiopsis leidyi and Pleurobrachia bachei, among our earliest metazoan ancestors. Sequence alignments and phylogenetic analysis show that these form a distinct clade from the well-characterized AMPA, kainate, and NMDA iGluR subtypes found in vertebrates. Although annotated as glutamate and kainate receptors, crystal structures of the ML032222a and PbiGluR3 ligand-binding domains (LBDs) reveal endogenous glycine in the binding pocket, whereas ligand-binding assays show that glycine binds with nanomolar affinity; biochemical assays and structural analysis establish that glutamate is occluded from the binding cavity. Further analysis reveals ctenophore-specific features, such as an interdomain Arg-Glu salt bridge, present only in subunits that bind glycine, but also a conserved disulfide in loop 1 of the LBD that is found in all vertebrate NMDA but not AMPA or kainate receptors. We hypothesize that ctenophore iGluRs are related to an early ancestor of NMDA receptors, suggesting a common evolutionary path for ctenophores and bilaterian species, and suggest that future work should consider both glycine and glutamate as candidate neurotransmitters in ctenophore species. PMID:26460032

  4. Early Use of the NMDA Receptor Antagonist Ketamine in Refractory and Superrefractory Status Epilepticus

    PubMed Central

    Zeiler, F. A.

    2015-01-01

    Refractory status epilepticus (RSE) and superrefractory status epilepticus (SRSE) pose a difficult clinical challenge. Multiple cerebral receptor and transporter changes occur with prolonged status epilepticus leading to pharmacoresistance patterns unfavorable for conventional antiepileptics. In particular, n-methyl-d-aspartate (NMDA) receptor upregulation leads to glutamate mediated excitotoxicity. Targeting these NMDA receptors may provide a novel approach to otherwise refractory seizures. Ketamine has been utilized in RSE. Recent systematic review indicates 56.5% and 63.5% cessation in seizures in adults and pediatrics, respectively. No complications were described. We should consider earlier implementation of ketamine or other NMDA receptor antagonists, for RSE. Prospective study of early implementation of ketamine should shed light on the role of such medications in RSE. PMID:25649724

  5. The function of the NMDA-receptor during normal brain aging.

    PubMed

    Müller, W E; Stoll, S; Scheuer, K; Meichelböck, A

    1994-01-01

    Age-related changes of N-methyl-D-aspartate (NMDA) receptors have been found in cortical areas and in the hippocampus of many species. On the basis of a variety of experimental observations it has been suggested that the decrease of NMDA-receptor density might be one of the causative factors of the cognitive decline with aging. Based on these findings several strategies have been developed to improve cognition by compensating the NMDA-receptor deficits in aging. The most promising approaches are the indirect activation of glutamatergic neurotransmission by agonists of the glycine site or the restoration of the age-related deficit of receptor density by several nootropics. PMID:7897387

  6. Enantiopure Indolo[2,3-a]quinolizidines: Synthesis and Evaluation as NMDA Receptor Antagonists.

    PubMed

    Pereira, Nuno A L; Sureda, Francesc X; Pérez, Maria; Amat, Mercedes; Santos, Maria M M

    2016-01-01

    Enantiopure tryptophanol is easily obtained from the reduction of its parent natural amino acid trypthophan (available from the chiral pool), and can be used as chiral auxiliary/inductor to control the stereochemical course of a diastereoselective reaction. Furthermore, enantiopure tryptophanol is useful for the syntheses of natural products or biological active molecules containing the aminoalcohol functionality. In this communication, we report the development of a small library of indolo[2,3-a]quinolizidines and evaluation of their activity as N-Methyl d-Aspartate (NMDA) receptor antagonists. The indolo[2,3-a]quinolizidine scaffold was obtained using the following key steps: (i) a stereoselective cyclocondensation of (S)- or (R)-tryptophanol with appropriate racemic δ-oxoesters; (ii) a stereocontrolled cyclization on the indole nucleus. The synthesized enantiopure indolo[2,3-a]quinolizidines were evaluated as NMDA receptor antagonists and one compound was identified to be 2.9-fold more potent as NMDA receptor blocker than amantadine (used in the clinic for Parkinson's disease). This compound represents a hit compound for the development of novel NMDA receptor antagonists with potential applications in neurodegenerative disorders associated with overactivation of NMDA receptors. PMID:27509489

  7. Current Evidence of Chinese Herbal Constituents with Effects on NMDA Receptor Blockade

    PubMed Central

    Liang, Willmann; Lam, Wai Ping; Tang, Hong Chai; Leung, Ping Chung; Yew, David T.

    2013-01-01

    NMDA receptor (NMDA-R) is an important molecular entity governing a wide range of functions in the central nervous system. For example, the NMDA-R is involved in memory and cognition, and impairment of both (as in Alzheimer’s Disease) is attributed to NMDA-mediated neurotoxicity. With greater understanding of the NMDA-R structure, antagonists with varying degrees of binding-site and subtype selectivity have been developed and put into clinical use. Discovery of target-specific Chinese herbs have also been made in parallel. This article provides an overview of the known active sites on the NMDA-R, followed by a discussion of the relevant herbs and their constituents. Experimental evidence supporting the inhibitory role of the herbal compounds on the NMDA-R is highlighted. For some of the compounds, potential research directions are also proposed to further elucidate the underlying mechanisms of the herbs. It is envisaged that future investigations based on the present data will allow more clinically relevant herbs to be identified. PMID:24276380

  8. A Metabotropic-Like Flux-Independent NMDA Receptor Regulates Ca2+ Exit from Endoplasmic Reticulum and Mitochondrial Membrane Potential in Cultured Astrocytes

    PubMed Central

    Montes de Oca Balderas, Pavel; Aguilera, Penélope

    2015-01-01

    Astrocytes were long thought to be only structural cells in the CNS; however, their functional properties support their role in information processing and cognition. The ionotropic glutamate N-methyl D-aspartate (NMDA) receptor (NMDAR) is critical for CNS functions, but its expression and function in astrocytes is still a matter of research and debate. Here, we report immunofluorescence (IF) labeling in rat cultured cortical astrocytes (rCCA) of all NMDAR subunits, with phenotypes suggesting their intracellular transport, and their mRNA were detected by qRT-PCR. IF and Western Blot revealed GluN1 full-length synthesis, subunit critical for NMDAR assembly and transport, and its plasma membrane localization. Functionally, we found an iCa2+ rise after NMDA treatment in Fluo-4-AM labeled rCCA, an effect blocked by the NMDAR competitive inhibitors D(-)-2-amino-5-phosphonopentanoic acid (APV) and Kynurenic acid (KYNA) and dependent upon GluN1 expression as evidenced by siRNA knock down. Surprisingly, the iCa2+ rise was not blocked by MK-801, an NMDAR channel blocker, or by extracellular Ca2+ depletion, indicating flux-independent NMDAR function. In contrast, the IP3 receptor (IP3R) inhibitor XestosponginC did block this response, whereas a Ryanodine Receptor inhibitor did so only partially. Furthermore, tyrosine kinase inhibition with genistein enhanced the NMDA elicited iCa2+ rise to levels comparable to those reached by the gliotransmitter ATP, but with different population dynamics. Finally, NMDA depleted the rCCA mitochondrial membrane potential (mΔψ) measured with JC-1. Our results demonstrate that rCCA express NMDAR subunits which assemble into functional receptors that mediate a metabotropic-like, non-canonical, flux-independent iCa2+ increase. PMID:25954808

  9. Potentiation of GluN2C/D NMDA receptor subtypes in the amygdala facilitates the retention of fear and extinction learning in mice.

    PubMed

    Ogden, Kevin K; Khatri, Alpa; Traynelis, Stephen F; Heldt, Scott A

    2014-02-01

    NMDA receptors are glutamate receptor ion channels that contribute to synaptic plasticity and are important for many forms of learning and memory. In the amygdala, NMDA receptors are critical for the acquisition, retention, and extinction of classically conditioned fear responses. Although the GluN2B subunit has been implicated in both the acquisition and extinction of conditioned fear, GluN2C-knockout mice show reduced conditioned fear responses. Moreover, D-cycloserine (DCS), which facilitates fear extinction, selectively enhances the activity of GluN2C-containing NMDA receptors. To further define the contribution of GluN2C receptors to fear learning, we infused the GluN2C/GluN2D-selective potentiator CIQ bilaterally into the basolateral amygdala (3, 10, or 30 μg/side) following either fear conditioning or fear extinction training. CIQ both increased the expression of conditioned fear 24 h later and enhanced the extinction of the previously conditioned fear response. These results support a critical role for GluN2C receptors in the amygdala in the consolidation of learned fear responses and suggest that increased activity of GluN2C receptors may underlie the therapeutic actions of DCS. PMID:24008353

  10. Synthesis of 4-(aminoalkyl) substituted 1,3-dioxanes as potent NMDA and σ receptor antagonists.

    PubMed

    Utech, Tina; Köhler, Jens; Wünsch, Bernhard

    2011-06-01

    Elongation of the distance between the oxygen heterocycle and the basic amino moiety or ring expansion of the oxygen heterocycle of the NMDA receptor antagonists dexoxadrol and etoxadrol led to compounds with promising NMDA receptor affinity. Herein the combination of both structural features, i.e. elongation of the O-heterocycle--amine distance with a 1,3-dioxane ring is envisaged. The synthesis of aminoethyl-1,3-dioxanes 13, 22, 23 and 29 was performed by transacetalization of various acetals with pentane-1,3,5-triol, activation of the remaining free OH moiety with tosyl chloride and subsequent nucleophilic substitution. The corresponding 3-aminopropyl derivatives 33-35 were prepared by substitution of the tosylates with KCN and LiAlH4 reduction. The highest NMDA receptor affinity was found for 1,3-dioxanes with a phenyl and an ethyl residue at the acetalic position (23) followed by diphenyl (22) and monophenyl derivatives (13). Generally the NMDA affinity of primary amines is higher than the NMDA affinity of secondary and tertiary amines. Altogether the primary amine 23a (Ki=24 nM) represents the most promising NMDA receptor antagonist of this series exceeding the NMDA affinity of the mono-homologues (2-aminoethyl)-1,3-dioxolanes (3,4) and (aminomethyl)-1,3-dioxanes (5,6). Whereas the primary amine 23a turned out to be selective against σ1 and σ2 receptors the benzylamine 13d was identified as potent (Ki=19 nM) and selective σ1 antagonist, which showed extraordinarily high antiallodynic activity in the capsaicin assay. PMID:21444132

  11. Gene Expression Switching of Receptor Subunits in Human Brain Development

    PubMed Central

    Bar-Shira, Ossnat; Maor, Ronnie; Chechik, Gal

    2015-01-01

    Synaptic receptors in the human brain consist of multiple protein subunits, many of which have multiple variants, coded by different genes, and are differentially expressed across brain regions and developmental stages. The brain can tune the electrophysiological properties of synapses to regulate plasticity and information processing by switching from one protein variant to another. Such condition-dependent variant switch during development has been demonstrated in several neurotransmitter systems including NMDA and GABA. Here we systematically detect pairs of receptor-subunit variants that switch during the lifetime of the human brain by analyzing postmortem expression data collected in a population of donors at various ages and brain regions measured using microarray and RNA-seq. To further detect variant pairs that co-vary across subjects, we present a method to quantify age-corrected expression correlation in face of strong temporal trends. This is achieved by computing the correlations in the residual expression beyond a cubic-spline model of the population temporal trend, and can be seen as a nonlinear version of partial correlations. Using these methods, we detect multiple new pairs of context dependent variants. For instance, we find a switch from GLRA2 to GLRA3 that differs from the known switch in the rat. We also detect an early switch from HTR1A to HTR5A whose trends are negatively correlated and find that their age-corrected expression is strongly positively correlated. Finally, we observe that GRIN2B switch to GRIN2A occurs mostly during embryonic development, presumably earlier than observed in rodents. These results provide a systematic map of developmental switching in the neurotransmitter systems of the human brain. PMID:26636753

  12. Opposite Roles of NMDA Receptors in Relapsing and Primary Progressive Multiple Sclerosis

    PubMed Central

    Rossi, Silvia; Studer, Valeria; Moscatelli, Alessandro; Motta, Caterina; Coghe, Giancarlo; Fenu, Giuseppe; Caillier, Stacy; Buttari, Fabio; Mori, Francesco; Barbieri, Francesca; Castelli, Maura; De Chiara, Valentina; Monteleone, Fabrizia; Mancino, Raffaele; Bernardi, Giorgio; Baranzini, Sergio E.; Marrosu, Maria G.; Oksenberg, Jorge R.; Centonze, Diego

    2013-01-01

    Synaptic transmission and plasticity mediated by NMDA receptors (NMDARs) could modulate the severity of multiple sclerosis (MS). Here the role of NMDARs in MS was first explored in 691 subjects carrying specific allelic variants of the NR1 subunit gene or of the NR2B subunit gene of this glutamate receptor. The analysis was replicated for significant SNPs in an independent sample of 1548 MS subjects. The C allele of rs4880213 was found to be associated with reduced NMDAR-mediated cortical excitability, and with increased probability of having more disability than the CT/TT MS subjects. MS severity was higher in the CC group among relapsing-remitting MS (RR-MS) patients, while primary progressive MS (PP-MS) subjects homozygous for the T allele had more pronounced clinical worsening. Mean time to first relapse, but not to an active MRI scan, was lower in the CC group of RR-MS patients, and the number of subjects with two or more clinical relapses in the first two years of the disease was higher in CC compared to CT/TT group. Furthermore, the percentage of relapses associated with residual disability was lower in subjects carrying the T allele. Lesion load at the MRI was conversely unaffected by the C or T allele of this SNP in RR-MS patients. Axonal and neuronal degeneration at the optical coherence tomography was more severe in the TT group of PP-MS patients, while reduced retinal nerve fiber thickness had less consequences on visual acuity in RR-MS patients bearing the T allele. Finally, the T allele was associated with preserved cognitive abilities at the Rao’s brief repeatable neuropsychological battery in RR-MS. Signaling through glutamate NMDARs enhances both compensatory synaptic plasticity and excitotoxic neurodegeneration, impacting in opposite ways on RR-MS and PP-MS pathophysiological mechanisms. PMID:23840674

  13. NMDA receptors regulate nicotine-enhanced brain reward function and intravenous nicotine self-administration: role of the ventral tegmental area and central nucleus of the amygdala.

    PubMed

    Kenny, Paul J; Chartoff, Elena; Roberto, Marisa; Carlezon, William A; Markou, Athina

    2009-01-01

    Nicotine is considered an important component of tobacco responsible for the smoking habit in humans. Nicotine increases glutamate-mediated transmission throughout brain reward circuitries. This action of nicotine could potentially contribute to its intrinsic rewarding and reward-enhancing properties, which motivate consumption of the drug. Here we show that the competitive N-methyl-D-aspartate (NMDA) receptor antagonist LY235959 (0.5-2.5 mg per kg) abolished nicotine-enhanced brain reward function, reflected in blockade of the lowering of intracranial self-stimulation (ICSS) thresholds usually observed after experimenter-administered (0.25 mg per kg) or intravenously self-administered (0.03 mg per kg per infusion) nicotine injections. The highest LY235959 dose (5 mg per kg) tested reversed the hedonic valence of nicotine from positive to negative, reflected in nicotine-induced elevations of ICSS thresholds. LY235959 doses that reversed nicotine-induced lowering of ICSS thresholds also markedly decreased nicotine self-administration without altering responding for food reinforcement, whereas the alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor antagonist NBQX had no effects on nicotine intake. In addition, nicotine self-administration upregulated NMDA receptor subunit expression in the central nucleus of the amygdala (CeA) and ventral tegmental area (VTA), suggesting important interactions between nicotine and the NMDA receptor. Furthermore, nicotine (1 microM) increased NMDA receptor-mediated excitatory postsynaptic currents in rat CeA slices, similar to its previously described effects in the VTA. Finally, infusion of LY235959 (0.1-10 ng per side) into the CeA or VTA decreased nicotine self-administration. Taken together, these data suggest that NMDA receptors, including those in the CeA and VTA, gate the magnitude and valence of the effects of nicotine on brain reward systems, thereby regulating motivation to consume the drug. PMID:18418357

  14. Activity and protein kinase C regulate synaptic accumulation of N-methyl-D-aspartate (NMDA) receptors independently of GluN1 splice variant.

    PubMed

    Ferreira, Joana S; Rooyakkers, Amanda; She, Kevin; Ribeiro, Luis; Carvalho, Ana Luísa; Craig, Ann Marie

    2011-08-12

    NMDA receptors are calcium-permeable ionotropic receptors that detect coincident glutamate binding and membrane depolarization and are essential for many forms of synaptic plasticity in the mammalian brain. The obligatory GluN1 subunit of NMDA receptors is alternatively spliced at multiple sites, generating forms that vary in N-terminal N1 and C-terminal C1, C2, and C2' cassettes. Based on expression of GluN1 constructs in heterologous cells and in wild type neurons, the prevalent view is that the C-terminal cassettes regulate synaptic accumulation and its modulation by homeostatic activity blockade and by protein kinase C (PKC). Here, we tested the role of GluN1 splicing in regulated synaptic accumulation of NMDA receptors by lentiviral expression of individual GluN1 splice variants in hippocampal neurons cultured from GluN1 (-/-) mice. High efficiency transduction of GluN1 at levels similar to endogenous was achieved. Under control conditions, the C2' cassette mediated enhanced synaptic accumulation relative to the alternate C2 cassette, whereas the presence or absence of N1 or C1 had no effect. Surprisingly all GluN1 splice variants showed >2-fold increased synaptic accumulation with chronic blockade of NMDA receptor activity. Furthermore, in this neuronal rescue system, all GluN1 splice variants were equally rapidly dispersed upon activation of PKC. These results indicate that the major mechanisms mediating homeostatic synaptic accumulation and PKC dispersal of NMDA receptors occur independently of GluN1 splice isoform. PMID:21676872

  15. ROLE OF NMDA, NICOTINIC, AND GABA RECEPTORS IN THE STEADY STATE VISUAL EVOKED POTENTIAL IN RATS.

    EPA Science Inventory

    This manuscript characterizes the receptor pathways involved in pattern-evoked potential generation in rats

    " NMDA and nicotinic acetylcholine receptors appear to be involved in the generation of the steady-state pattern evoked response in vivo.

    " The pattern evok...

  16. Tyrosine phosphorylation regulates the endocytosis and surface expression of GluN3A-containing NMDA receptors.

    PubMed

    Chowdhury, Dhrubajyoti; Marco, Sonia; Brooks, Ian M; Zandueta, Aitor; Rao, Yijian; Haucke, Volker; Wesseling, John F; Tavalin, Steven J; Pérez-Otaño, Isabel

    2013-02-27

    Selective control of receptor trafficking provides a mechanism for remodeling the receptor composition of excitatory synapses, and thus supports synaptic transmission, plasticity, and development. GluN3A (formerly NR3A) is a nonconventional member of the NMDA receptor (NMDAR) subunit family, which endows NMDAR channels with low calcium permeability and reduced magnesium sensitivity compared with NMDARs comprising only GluN1 and GluN2 subunits. Because of these special properties, GluN3A subunits act as a molecular brake to limit the plasticity and maturation of excitatory synapses, pointing toward GluN3A removal as a critical step in the development of neuronal circuitry. However, the molecular signals mediating GluN3A endocytic removal remain unclear. Here we define a novel endocytic motif (YWL), which is located within the cytoplasmic C-terminal tail of GluN3A and mediates its binding to the clathrin adaptor AP2. Alanine mutations within the GluN3A endocytic motif inhibited clathrin-dependent internalization and led to accumulation of GluN3A-containing NMDARs at the cell surface, whereas mimicking phosphorylation of the tyrosine residue promoted internalization and reduced cell-surface expression as shown by immunocytochemical and electrophysiological approaches in recombinant systems and rat neurons in primary culture. We further demonstrate that the tyrosine residue is phosphorylated by Src family kinases, and that Src-activation limits surface GluN3A expression in neurons. Together, our results identify a new molecular signal for GluN3A internalization that couples the functional surface expression of GluN3A-containing receptors to the phosphorylation state of GluN3A subunits, and provides a molecular framework for the regulation of NMDAR subunit composition with implications for synaptic plasticity and neurodevelopment. PMID:23447623

  17. Nitric oxide modulates blood pressure through NMDA receptors in the rostral ventrolateral medulla of conscious rats.

    PubMed

    Machado, Natalia L S; Silva, Fernanda C S; Chianca, Deoclecio A; de Menezes, Rodrigo C

    2016-07-15

    The rostral ventrolateral medulla (RVLM) is an important site of cardiovascular control related to the tonic excitation and regulating the sympathetic vasomotor tone through local presympathetic neurons. Nitric oxide (NO) has been implicated in the modulation of neurotransmission by several areas of the central nervous system including the RVLM. However the pathways driving NO affects and the correlation between NO and glutamate-induced mechanisms are not well established. Here, we investigate the influence of NO on the cardiovascular response evoked by the activation of NMDA and non-NMDA glutamatergic receptors in the RVLM in conscious rats. For that, we examined the influence of acute inhibition of the NO production within the RVLM, by injecting the nonselective constitutive NOS inhibitor, l-NAME, on responses evoked by the microinjection of excitatory amino acids l-glutamate, NMDA or AMPA agonists into RVLM. Our results show that the injection of l-glutamate, NMDA or AMPA agonists into RVLM, unilaterally, induced a marked increase in the mean arterial pressure (MAP). Pretreatment with l-NAME reduced the hypertensive response evoked by the glutamate injection, and also abolished the pressor response induced by the injection of NMDA into the RVLM. However, blocking the NO synthesis did not alter the response produced by the injection of AMPA agonist. These data provide evidence that the glutamatergic neurotransmission within the RVLM depends on excitatory effects exerted by NO on NMDA receptors, and that this mechanism might be essential to regulate systemic blood pressure. PMID:27150817

  18. NR2B-containing NMDA receptors promote neural progenitor cell proliferation through CaMKIV/CREB pathway

    SciTech Connect

    Li, Mei; Zhang, Dong-Qing; Wang, Xiang-Zhen; Xu, Tie-Jun

    2011-08-12

    Highlights: {yields} The NR2B component of the NMDARs is important for the NSPC proliferation. {yields} pCaMKIV and pCREB exist in NSPCs. {yields} The CaMKIV/CREB pathway mediates NSPC proliferation. -- Abstract: Accumulating evidence indicates the involvement of N-methyl-D-aspartate receptors (NMDARs) in regulating neural stem/progenitor cell (NSPC) proliferation. Functional properties of NMDARs can be markedly influenced by incorporating the regulatory subunit NR2B. Here, we aim to analyze the effect of NR2B-containing NMDARs on the proliferation of hippocampal NSPCs and to explore the mechanism responsible for this effect. NSPCs were shown to express NMDAR subunits NR1 and NR2B. The NR2B selective antagonist, Ro 25-6981, prevented the NMDA-induced increase in cell proliferation. Moreover, we demonstrated that the phosphorylation levels of calcium/calmodulin-dependent protein kinase IV (CaMKIV) and cAMP response element binding protein (CREB) were increased by NMDA treatment, whereas Ro 25-6981 decreased them. The role that NR2B-containing NMDARs plays in NSPC proliferation was abolished when CREB phosphorylation was attenuated by CaMKIV silencing. These results suggest that NR2B-containing NMDARs have a positive role in regulating NSPC proliferation, which may be mediated through CaMKIV phosphorylation and subsequent induction of CREB activation.

  19. Anti-NMDA receptor encephalitis presenting as atypical anorexia nervosa: an adolescent case report.

    PubMed

    Mechelhoff, David; van Noort, Betteke Maria; Weschke, Bernhard; Bachmann, Christian J; Wagner, Christiane; Pfeiffer, Ernst; Winter, Sibylle

    2015-11-01

    Since 2007, more than 600 patients have been diagnosed with anti-N-methyl-D-aspartate (NMDA) receptor encephalitis, with almost 40 % of those affected being children or adolescents. In early phases of the illness, this life-threatening disease is characterized by psychiatric symptoms, such as depression, anxiety, obsessions, hallucinations or delusions. Consequently, a high percentage of patients receive psychiatric diagnoses at first, hindering the crucial early diagnosis and treatment of the anti-NMDA receptor encephalitis. We report on a 15-year-old girl initially presenting with pathological eating behaviour and significant weight loss resulting in an (atypical) anorexia nervosa (AN) diagnosis. Her early course of illness, diagnostic process, treatment and short-term outcome are described. This case report aims to raise awareness about the association between anorectic behaviour and anti-NMDA receptor encephalitis and highlight the importance of multidisciplinary teams in child and adolescent services. PMID:25663428

  20. IRSp53/BAIAP2 in dendritic spine development, NMDA receptor regulation, and psychiatric disorders.

    PubMed

    Kang, Jaeseung; Park, Haram; Kim, Eunjoon

    2016-01-01

    IRSp53 (also known as BAIAP2) is a multi-domain scaffolding and adaptor protein that has been implicated in the regulation of membrane and actin dynamics at subcellular structures, including filopodia and lamellipodia. Accumulating evidence indicates that IRSp53 is an abundant component of the postsynaptic density at excitatory synapses and an important regulator of actin-rich dendritic spines. In addition, IRSp53 has been implicated in diverse psychiatric disorders, including autism spectrum disorders, schizophrenia, and attention deficit/hyperactivity disorder. Mice lacking IRSp53 display enhanced NMDA (N-methyl-d-aspartate) receptor function accompanied by social and cognitive deficits, which are reversed by pharmacological suppression of NMDA receptor function. These results suggest the hypothesis that defective actin/membrane modulation in IRSp53-deficient dendritic spines may lead to social and cognitive deficits through NMDA receptor dysfunction. This article is part of the Special Issue entitled 'Synaptopathy--from Biology to Therapy'. PMID:26275848

  1. Differential involvement of amygdala and cortical NMDA receptors activation upon encoding in odor fear memory.

    PubMed

    Hegoburu, Chloé; Parrot, Sandrine; Ferreira, Guillaume; Mouly, Anne-Marie

    2014-12-01

    Although the basolateral amygdala (BLA) plays a crucial role for the acquisition of fear memories, sensory cortices are involved in their long-term storage in rats. However, the time course of their respective involvement has received little investigation. Here we assessed the role of the glutamatergic N-methyl-d-aspartate (NMDA) receptors in the BLA and olfactory cortex at discrete moments of an odor fear conditioning session. We showed that NMDA receptors in BLA are critically involved in odor fear acquisition during the first association but not during the next ones. In the cortex, NMDA receptor activation at encoding is not necessary for recent odor fear memory while its role in remote memory storage needs further investigation. PMID:25403452

  2. The opioid peptide dynorphin directly blocks NMDA receptor channels in the rat.

    PubMed Central

    Chen, L; Gu, Y; Huang, L Y

    1995-01-01

    1. The actions of dynorphin on N-methyl-D-aspartate (NMDA) responses were examined in acutely dissociated trigeminal neurons in rat. Whole-cell and single-channel currents were recorded using the patch clamp technique. 2. Dynorphins reduced NMDA-activated currents (INMDA). The IC50 was 0.25 microM for dynorphin (1-32), 1.65 microM for dynorphin (1-17) and 1.8 microM for dynorphin (1-13). 3. The blocking action of dynorphin is voltage independent. 4. The inhibitory action of dynorphin cannot be blocked by high concentration of the non-selective opioid receptor antagonist naloxone, nor by the specific kappa-opioid receptor antagonist nor-Binaltorphimine (nor-BNI). 5. Single-channel analyses indicate that dynorphin reduces the fraction of time the channel is open without altering the channel conductance. 6. We propose that dynorphin acts directly on NMDA receptors. PMID:7537820

  3. EVALUATING THE NMDA-GLUTAMATE RECEPTOR AS A SITE OF ACTION FOR TOLUENE USING PATTERN ELICITED VISUAL EVOKED POTENTIALS.

    EPA Science Inventory

    In vitro studies have demonstrated that toluene disrupts the function of NMDA-glutamate receptors, as well as other channels. This has led to the hypothesis that effects on NMDA receptor function may contribute to toluene neurotoxicity, CNS depression, and altered visual evoked ...

  4. The N-terminal domains of both NR1 and NR2 subunits determine allosteric Zn2+ inhibition and glycine affinity of N-methyl-D-aspartate receptors.

    PubMed

    Madry, Christian; Mesic, Ivana; Betz, Heinrich; Laube, Bodo

    2007-12-01

    The N-methyl-D-aspartate (NMDA) subtype of ionotropic glutamate receptors (iGluRs) is a tetrameric protein composed of homologous NR1 and NR2 subunits, which require the binding of glycine and glutamate, respectively, for efficient channel gating. The extracellular N-terminal domains (NTDs) of iGluR subunits show sequence homology to the bacterial periplasmic leucine/isoleucine/valine binding protein (LIVBP) and have been implicated in iGluR assembly, trafficking, and function. Here, we investigated how deletion of the NR1- and NR2-NTDs affects the expression and function of NMDA receptors. Both proteolytic cleavage of the NR1-NTD from assembled NR1/NR2 receptors and coexpression of the NTD-deleted NR1 subunit with wild-type or NTD-deleted NR2 subunits resulted in agonist-gated channels that closely resembled wild-type receptors. This indicates that the NTDs of both NMDA receptor subunits are not essential for receptor assembly and function. However, deletion of either the NR1 or the NR2 NTD eliminated high-affinity, allosteric inhibition of agonist-induced currents by Zn2+ and ifenprodil, consistent with the idea that interdomain interactions between these domains are important for allosteric receptor modulation. Furthermore, by replacing the NR2A-NTD with the NR2B NTD, and vice versa, the different glycine affinities of NR1/NR2A and NR1/NR2B receptors were found to be determined by their respective NR2-NTDs. Together, these data show that the NTDs of both the NR1 and NR2 subunits determine allosteric inhibition and glycine potency but are not required for NMDA receptor assembly. PMID:17878266

  5. Dexras1 a unique ras-GTPase interacts with NMDA receptor activity and provides a novel dissociation between anxiety, working memory and sensory gating.

    PubMed

    Carlson, G C; Lin, R E; Chen, Y; Brookshire, B R; White, R S; Lucki, I; Siegel, S J; Kim, S F

    2016-05-13

    Dexras1 is a novel GTPase that acts at a confluence of signaling mechanisms associated with psychiatric and neurological disease including NMDA receptors, NOS1AP and nNOS. Recent work has shown that Dexras1 mediates iron trafficking and NMDA-dependent neurodegeneration but a role for Dexras1 in normal brain function or psychiatric disease has not been studied. To test for such a role, mice with germline knockout (KO) of Dexras1 were assayed for behavioral abnormalities as well as changes in NMDA receptor subunit protein expression. Because Dexras1 is up-regulated during stress or by dexamethasone treatment, we included measures associated with emotion including anxiety and depression. Baseline anxiety-like measures (open field and zero maze) were not altered, nor were depression-like behavior (tail suspension). Measures of memory function yielded mixed results, with no changes in episodic memory (novel object recognition) but a significant decrement on working memory (T-maze). Alternatively, there was an increase in pre-pulse inhibition (PPI), without concomitant changes in either startle amplitude or locomotor activity. PPI data are consistent with the direction of change seen following exposure to dopamine D2 antagonists. An examination of NMDA subunit expression levels revealed an increased expression of the NR2A subunit, contrary to previous studies demonstrating down-regulation of the receptor following antipsychotic exposure (Schmitt et al., 2003) and up-regulation after exposure to isolation rearing (Turnock-Jones et al., 2009). These findings suggest a potential role for Dexras1 in modulating a selective subset of psychiatric symptoms, possibly via its interaction with NMDARs and/or other disease-related binding-partners. Furthermore, data suggest that modulating Dexras1 activity has contrasting effects on emotional, sensory and cognitive domains. PMID:26946266

  6. NMDA-Receptor Activation but Not Ion Flux Is Required for Amyloid-Beta Induced Synaptic Depression

    PubMed Central

    Tamburri, Albert; Dudilot, Anthony; Licea, Sara; Bourgeois, Catherine; Boehm, Jannic

    2013-01-01

    Alzheimer disease is characterized by a gradual decrease of synaptic function and, ultimately, by neuronal loss. There is considerable evidence supporting the involvement of oligomeric amyloid-beta (Aβ) in the etiology of Alzheimer’s disease. Historically, AD research has mainly focused on the long-term changes caused by Aβ rather than analyzing its immediate effects. Here we show that acute perfusion of hippocampal slice cultures with oligomeric Aβ depresses synaptic transmission within 20 minutes. This depression is dependent on synaptic stimulation and the activation of NMDA-receptors, but not on NMDA-receptor mediated ion flux. It, therefore, appears that Aβ dependent synaptic depression is mediated through a use-dependent metabotropic-like mechanism of the NMDA-receptor, but does not involve NMDA-receptor mediated synaptic transmission, i.e. it is independent of calcium flux through the NMDA-receptor. PMID:23750255

  7. Effects of N-methyl-D-aspartate (NMDA) receptor blockade on breathing pattern in newborn cat.

    PubMed

    Schweitzer, P; Pierrefiche, O; Foutz, A S; Denavit-Saubié, M

    1990-11-01

    We gave newborn kittens the N-methyl-D-aspartate (NMDA) receptor blocker MK-801 systemically while recording their breathing patterns by the barometric method. Unlike pentobarbital, MK-801 at an anaesthetic dose increased the relative length of inspiration within the respiratory cycle. The section of both vagus nerves under MK-801 produced apneustic breathing, whereas vagotomy under pentobarbital had no such effect. We conclude that the central inspiratory-termination mechanism mediated through NMDA receptors and the vagally-mediated mechanism that independently 'switches off' inspiration are both functional at birth. PMID:2148125

  8. Anti-N-methyl-D-aspartate (NMDA) receptor encephalitis in a young Lebanese girl.

    PubMed

    Safadieh, Layal; Dabbagh, Omar

    2013-10-01

    Anti-N-methyl-D-aspartate (NMDA) receptor encephalitis is a recently recognized autoimmune neurologic disorder that presents with severe neuropsychiatric symptoms in previously healthy children. A 4-year-old Lebanese girl presented with new-onset behavioral changes, orofacial dyskinesias, fluctuation in consciousness, inability to walk, and mutism. Antibodies directed against NMDA receptors were detected in the patient's serum and cerebrospinal fluid. Prompt treatment with a single course of intravenous immunoglobulin resulted in early complete recovery. This is the first case report of a Middle Eastern child affected with this condition. PMID:22992990

  9. Quinazolin-4-one derivatives: A novel class of non-competitive NR2C/D subunit-selective N-methyl-D-aspartate receptor antagonists

    PubMed Central

    Mosley, Cara A.; Acker, Timothy M.; Hansen, Kasper B.; Mullasseril, Praseeda; Andersen, Karen T.; Le, Phuong; Vellano, Kimberly M.; Bräuner-Osborne, Hans; Liotta, Dennis C.; Traynelis, Stephen F.

    2010-01-01

    We describe a new class of subunit-selective antagonists of N-methyl D-Aspartate (NMDA)-selective ionotropic glutamate receptors that contain the (E)-3-phenyl-2-styrylquinazolin-4(3H)-one backbone. The inhibition of recombinant NMDA receptor function induced by these quinazolin-4-one derivatives is non-competitive and voltage-independent, suggesting that this family of compounds does not exert action on the agonist binding site of the receptor or block the channel pore. The compounds described here resemble CP-465,022 ((S)-3-(2-chlorophenyl)-2-[2-(6-diethylaminomethyl-pyridin-2-yl)-vinyl]-6-fluoro-3H-quinazolin-4-one), a non-competitive antagonist of AMPA-selective glutamate receptors. However, modification of ring substituents resulted in analogues with greater than 100-fold selectivity for recombinant NMDA receptors over AMPA and kainate receptors. Furthermore, within this series of compounds, analogues were identified with 50-fold selectivity for recombinant NR2C/D-containing receptors over NR2A/B containing receptors. These compounds represent a new class of non-competitive subunit-selective NMDA receptor antagonists. PMID:20684595

  10. Dietary n-3 polyunsaturated fatty acid depletion activates caspases and decreases NMDA receptors in the brain of a transgenic mouse model of Alzheimer's disease.

    PubMed

    Calon, Frédéric; Lim, Giselle P; Morihara, Takashi; Yang, Fusheng; Ubeda, Oliver; Salem, Norman; Frautschy, Sally A; Cole, Greg M

    2005-08-01

    Epidemiological data indicate that low n-3 polyunsaturated fatty acids (PFA) intake is a readily manipulated dietary risk factor for Alzheimer's disease (AD). Studies in animals confirm the deleterious effect of n-3 PFA depletion on cognition and on dendritic scaffold proteins. Here, we show that in transgenic mice overexpressing the human AD gene APPswe (Tg2576), safflower oil-induced n-3 PFA deficiency caused a decrease in N-methyl-D-aspartate (NMDA) receptor subunits, NR2A and NR2B, in the cortex and hippocampus with no loss of the presynaptic markers, synaptophysin and synaptosomal-associated protein 25 (SNAP-25). n-3 PFA depletion also decreased the NR1 subunit in the hippocampus and Ca2+/calmodulin-dependent protein kinase (CaMKII) in the cortex of Tg2576 mice. These effects of dietary n-3 PFA deficiency were greatly amplified in Tg2576 mice compared to nontransgenic mice. Loss of the NR2B receptor subunit was not explained by changes in mRNA expression, but correlated with p85alpha phosphatidylinositol 3-kinase levels. Most interestingly, n-3 PFA deficiency dramatically increased levels of protein fragments, corresponding to caspase/calpain-cleaved fodrin and gelsolin in Tg2576 mice. This effect was minimal in nontransgenic mice suggesting that n-3 PFA depletion potentiated caspase activation in the Tg2576 mouse model of AD. Dietary supplementation with docosahexaenoic acid (DHA; 22 : 6n-3) partly protected from NMDA receptor subunit loss and accumulation of fodrin and gelsolin fragments but fully prevented CaMKII decrease. The marked effect of dietary n-3 PFA on NMDA receptors and caspase/calpain activation in the cortex of an animal model of AD provide new insights into how dietary essential fatty acids may influence cognition and AD risk. PMID:16101743

  11. Potentiation of NMDA receptor-mediated transmission in striatal cholinergic interneurons.

    PubMed

    Oswald, Manfred J; Schulz, Jan M; Kelsch, Wolfgang; Oorschot, Dorothy E; Reynolds, John N J

    2015-01-01

    Pauses in the tonic firing of striatal cholinergic interneurons (CINs) emerge during reward-related learning in response to conditioning of a neutral cue. We have previously reported that augmenting the postsynaptic response to cortical afferents in CINs is coupled to the emergence of a cell-intrinsic afterhyperpolarization (AHP) underlying pauses in tonic activity. Here we investigated in a bihemispheric rat-brain slice preparation the mechanisms of synaptic plasticity of excitatory afferents to CINs and the association with changes in the AHP. We found that high frequency stimulation (HFS) of commissural corticostriatal afferents from the contralateral hemisphere induced a robust long-term depression (LTD) of postsynaptic potentials (PSP) in CINs. Depression of the PSP of smaller magnitude and duration was observed in response to HFS of the ipsilateral white matter or cerebral cortex. In Mg(2+)-free solution HFS induced NMDA receptor-dependent potentiation of the PSP, evident in both the maximal slope and amplitude of the PSP. The increase in maximal slope corroborates previous findings, and was blocked by antagonism of either D1-like dopamine receptors with SCH23390 or D2-like dopamine receptors with sulpiride during HFS in Mg(2+)-free solution. Potentiation of the slower PSP amplitude component was due to augmentation of the NMDA receptor-mediated potential as this was completely reversed on subsequent application of the NMDA receptor antagonist AP5. HFS similarly potentiated NMDA receptor currents isolated by blockade of AMPA/kainate receptors with CNQX. The plasticity-induced increase in the slow PSP component was directly associated with an increase in the subsequent AHP. Thus plasticity of cortical afferent synapses is ideally suited to influence the cue-induced firing dynamics of CINs, particularly through potentiation of NMDA receptor-mediated synaptic transmission. PMID:25914618

  12. Methylphenidate Enhances NMDA-Receptor Response in Medial Prefrontal Cortex via Sigma-1 Receptor: A Novel Mechanism for Methylphenidate Action

    PubMed Central

    Liu, Yue; Ji, Xiao-Hua; Peng, Ji-Yun; Zhang, Xue-Han; Zhen, Xue-Chu; Li, Bao-Ming

    2012-01-01

    Methylphenidate (MPH), commercially called Ritalin or Concerta, has been widely used as a drug for Attention Deficit Hyperactivity Disorder (ADHD). Noteworthily, growing numbers of young people using prescribed MPH improperly for pleasurable enhancement, take high risk of addiction. Thus, understanding the mechanism underlying high level of MPH action in the brain becomes an important goal nowadays. As a blocker of catecholamine transporters, its therapeutic effect is explained as being due to proper modulation of D1 and α2A receptor. Here we showed that higher dose of MPH facilitates NMDA-receptor mediated synaptic transmission via a catecholamine-independent mechanism, in layer V∼VI pyramidal cells of the rat medial prefrontal cortex (PFC). To indicate its postsynaptic action, we next found that MPH facilitates NMDA-induced current and such facilitation could be blocked by σ1 but not D1/5 and α2 receptor antagonists. And this MPH eliciting enhancement of NMDA-receptor activity involves PLC, PKC and IP3 receptor mediated intracellular Ca2+ increase, but does not require PKA and extracellular Ca2+ influx. Our additional pharmacological studies confirmed that higher dose of MPH increases locomotor activity via interacting with σ1 receptor. Together, the present study demonstrates for the first time that MPH facilitates NMDA-receptor mediated synaptic transmission via σ1 receptor, and such facilitation requires PLC/IP3/PKC signaling pathway. This novel mechanism possibly explains the underlying mechanism for MPH induced addictive potential and other psychiatric side effects. PMID:23284812

  13. State-dependent changes in astrocyte regulation of extrasynaptic NMDA receptor signalling in neurosecretory neurons.

    PubMed

    Fleming, Tiffany M; Scott, Victoria; Naskar, Krishna; Joe, Natalie; Brown, Colin H; Stern, Javier E

    2011-08-15

    Despite the long-established presence of glutamate NMDA receptors at extrasynaptic sites (eNMDARs), their functional roles remain poorly understood. Factors influencing the concentration and time course of glutamate in the extrasynaptic space, such as the topography of the neuronal–glial microenvironment, as well as glial glutamate transporters, are expected to affect eNMDAR-mediated signalling strength. In this study, we used in vitro and in vivo electrophysiological recordings to assess the properties, functional relevance and modulation of a persistent excitatory current mediated by activation of eNMDARs in hypothalamic supraoptic nucleus (SON) neurons. We found that ambient glutamate of a non-synaptic origin activates eNMDARs to mediate a persistent excitatory current (termed tonic I(NMDA)), which tonically stimulates neuronal activity. Pharmacological blockade of GLT1 astrocyte glutamate transporters, as well as the gliotoxin α-aminodadipic acid, enhanced tonic I(NMDA) and neuronal activity, supporting an astrocyte regulation of tonic I(NMDA) strength. Dehydration, a physiological challenge known to increase SON firing activity and to induce neuroglial remodelling, including reduced neuronal ensheathment by astrocyte processes, resulted in blunted GLT1 efficacy, enhanced tonic I(NMDA) strength, and increased neuronal activity. Taken together, our studies support the view that glial modulation of tonic I(NMDA) activation contributes to regulation of SON neuronal activity, contributing in turn to neuronal homeostatic responses during a physiological challenge. PMID:21690192

  14. Blueberry-enriched diet ameliorates age-related declines in NMDA receptor-dependent LTP

    PubMed Central

    Bickford, Paula C.; Browning, Michael D.

    2008-01-01

    NMDA receptor-dependent long-term potentiation (LTP) in the hippocampus is widely accepted as a cellular substrate for memory formation. Age-related declines in the expression of both NMDAR-dependent LTP and NMDAR subunit proteins in the CA1 region of the hippocampus have been well characterized and likely underlie age-related memory impairment. In the current study, we examined NMDAR-dependent LTP in young Fischer 344 rats (4 months old) and aged rats (24 months old) given either a control diet or a diet supplemented with blueberry extract for 6–8 weeks. NMDAR-dependent LTP was evoked by high-frequency stimulation (HFS) in the presence of nifedipine, to eliminate voltage-gated calcium channel LTP. Field excitatory postsynaptic potentials (fEPSPs) were increased by 57% 1 h after HFS in young animals, but this potentiation was reduced to 31% in aged animals. Supplementation of the diet with blueberry extract elevated LTP (63%) in aged animals to levels seen in young. The normalization of LTP may be due to the blueberry diet preventing a decline in synaptic strength, as measured by the slope of the fEPSP for a given fiber potential. The blueberry diet did not prevent age-related declines in NMDAR protein expression. However, phosphorylation of a key tyrosine residue on the NR2B subunit, important for increasing NMDAR function, was enhanced by the diet, suggesting that an increase in NMDAR function might overcome the loss in protein. This report provides evidence that dietary alterations later in life may prevent or postpone the cognitive declines associated with aging. PMID:19424850

  15. Relief learning is dependent on NMDA receptor activation in the nucleus accumbens

    PubMed Central

    Mohammadi, Milad; Fendt, Markus

    2015-01-01

    Background and Purpose Recently, we demonstrated that the nucleus accumbens (NAC) is required for the acquisition and expression of relief memory. The purpose of this study was to investigate the role of NMDA receptors within the NAC in relief learning. Experimental Approach The NMDA receptor antagonist 2-amino-5-phosphonopentanoic acid (AP-5) was injected into the NAC. The effects of these injections on the acquisition and expression of relief memory, as well as on the reactivity to aversive electric stimuli, were tested. Key Results Intra-accumbal AP-5 injections blocked the acquisition but not the expression of relief memory. Furthermore, reactivity to aversive electric stimuli was not affected by the AP-5 injections. Conclusion and Implication The present data indicate that NMDA-dependent plasticity within the NAC is crucial for the acquisition of relief memory. PMID:25572550

  16. Mechanisms for Antagonistic Regulation of AMPA and NMDA-D1 Receptor Complexes at Postsynaptic Sites

    NASA Technical Reports Server (NTRS)

    Schumann, Johann; Scheler, Gabriele

    2004-01-01

    From the analysis of these pathways we conclude that postsynaptic processes that regulate synaptic transmission undergo significant cross-talk with respect to glutamatergic and neuromodulatory (dopamine) signals. The main hypothesis is that of a compensatory regulation, a competitive switch between the induction of increased AMPA conductance by CaMKII-dependent phosphorylation and reduced expression of PP2A, and increased D1 receptor sensitivity and expression by increased PKA, PP2A and decreased PP-1/calcineurin expression. Both types of plasticity are induced by NMDA receptor activation and increased internal calcium, they require different internal conditions to become expressed. Specifically we propose that AMPA regulation and D1 regulation are inversely coupled;The net result may be a bifurcation of synaptic state into predominantly AMPA or NMDA-D1 synapses. This could have functional consequences: stable connections for AMPA and conditional gating for NMDA-D1 synapses.

  17. Synergy of AMPA and NMDA Receptor Currents in Dopaminergic Neurons: A Modeling Study.

    PubMed

    Zakharov, Denis; Lapish, Christopher; Gutkin, Boris; Kuznetsov, Alexey

    2016-01-01

    Dopaminergic (DA) neurons display two modes of firing: low-frequency tonic and high-frequency bursts. The high frequency firing within the bursts is attributed to NMDA, but not AMPA receptor activation. In our models of the DA neuron, both biophysical and abstract, the NMDA receptor current can significantly increase their firing frequency, whereas the AMPA receptor current is not able to evoke high-frequency activity and usually suppresses firing. However, both currents are produced by glutamate receptors and, consequently, are often co-activated. Here we consider combined influence of AMPA and NMDA synaptic input in the models of the DA neuron. Different types of neuronal activity (resting state, low frequency, or high frequency firing) are observed depending on the conductance of the AMPAR and NMDAR currents. In two models, biophysical and reduced, we show that the firing frequency increases more effectively if both receptors are co-activated for certain parameter values. In particular, in the more quantitative biophysical model, the maximal frequency is 40% greater than that with NMDAR alone. The dynamical mechanism of such frequency growth is explained in the framework of phase space evolution using the reduced model. In short, both the AMPAR and NMDAR currents flatten the voltage nullcline, providing the frequency increase, whereas only NMDA prevents complete unfolding of the nullcline, providing robust firing. Thus, we confirm a major role of the NMDAR in generating high-frequency firing and conclude that AMPAR activation further significantly increases the frequency. PMID:27252643

  18. Synergy of AMPA and NMDA Receptor Currents in Dopaminergic Neurons: A Modeling Study

    PubMed Central

    Zakharov, Denis; Lapish, Christopher; Gutkin, Boris; Kuznetsov, Alexey

    2016-01-01

    Dopaminergic (DA) neurons display two modes of firing: low-frequency tonic and high-frequency bursts. The high frequency firing within the bursts is attributed to NMDA, but not AMPA receptor activation. In our models of the DA neuron, both biophysical and abstract, the NMDA receptor current can significantly increase their firing frequency, whereas the AMPA receptor current is not able to evoke high-frequency activity and usually suppresses firing. However, both currents are produced by glutamate receptors and, consequently, are often co-activated. Here we consider combined influence of AMPA and NMDA synaptic input in the models of the DA neuron. Different types of neuronal activity (resting state, low frequency, or high frequency firing) are observed depending on the conductance of the AMPAR and NMDAR currents. In two models, biophysical and reduced, we show that the firing frequency increases more effectively if both receptors are co-activated for certain parameter values. In particular, in the more quantitative biophysical model, the maximal frequency is 40% greater than that with NMDAR alone. The dynamical mechanism of such frequency growth is explained in the framework of phase space evolution using the reduced model. In short, both the AMPAR and NMDAR currents flatten the voltage nullcline, providing the frequency increase, whereas only NMDA prevents complete unfolding of the nullcline, providing robust firing. Thus, we confirm a major role of the NMDAR in generating high-frequency firing and conclude that AMPAR activation further significantly increases the frequency. PMID:27252643

  19. Brain-derived neurotrophic factor rapidly increases NMDA receptor channel activity through Fyn-mediated phosphorylation.

    PubMed

    Xu, Fei; Plummer, Mark R; Len, Guo-Wei; Nakazawa, Takanobu; Yamamoto, Tadashi; Black, Ira B; Wu, Kuo

    2006-11-22

    Brain-derived neurotrophic factor (BDNF) is a potent modulator of hippocampal synaptic plasticity. Previously, we found that one of the targets of BDNF modulation is NR2B-containing NMDA receptors. Furthermore, exposure to the trophin rapidly increases NMDA receptor activity and enhances tyrosine phosphorylation of NR2B in cortical and hippocampal postsynaptic densities (PSDs), potentially linking receptor phosphorylation to synaptic plasticity. To define the specific NR2B residue(s) regulated by BDNF, we focused on tyrosine 1472, phosphorylation of which increases after LTP. BDNF rapidly increased phosphorylation in cortical PSDs. The tyrosine kinase Fyn is critical since BDNF-dependent phosphorylation was abolished in Fyn knockout mice. Single-channel patch clamp recordings showed that Fyn is required for the increase in NMDA receptor activity elicited by BDNF. Collectively, our results suggest that BDNF enhances phosphorylation of NR2B tyrosine 1472 through activation of Fyn, leading to alteration of NMDA receptor activity and increased synaptic transmission. PMID:17045972

  20. The HIV coat protein gp120 promotes forward trafficking and surface clustering of NMDA receptors in membrane microdomains

    PubMed Central

    Xu, Hangxiu; Bae, Mihyun; Tovar-y-Romo, Luis B.; Patel, Neha; Bandaru, Veera Venkata Ratnam; Pomerantz, Daniel; Steiner, Joseph; Haughey, Norman J.

    2011-01-01

    Infection by the Human immunodeficiency virus (HIV) can result in debilitating neurological syndromes collectively known as HIV associated neurocognitive disorders (HAND). While the HIV coat protein gp120 has been identified as a potent neurotoxin that enhances NMDA receptor function, the exact mechanisms for effect are not known. Here we provide evidence that gp120 activates two separate signaling pathways that converge to enhance NMDA-evoked calcium flux by clustering NMDA receptors in modified membrane microdomains. HIV gp120 enlarged, and stabilized the structure of lipid rafts on neuronal dendrites by mechanisms that involved a redox-regulated translocation of a sphingomyelin hydrolase (neutral sphingomyelinase-2; nSMase2) to the plasma membrane. A concurrent pathway was activated that enhanced the forward traffic of NMDA receptors by promoting a PKA-dependent phopshorylation of the NR1 C-terminal serine 897 (that masks an ER retention signal), followed by a PKC-dependent phosphorylation of serine 896 (important for surface expression). NMDA receptors were preferentially targeted to synapses, and clustered in modified membrane microdomains. In these conditions, NMDA receptors were unable to laterally disperse, and did not internalize, even in response to strong agonist induction. Focal NMDA-evoked calcium bursts were enhanced three-fold in these regions. Inhibiting membrane modification or NR1 phosphorylation prevented gp120 from enhancing the surface localization and clustering of NMDA receptors, while disrupting the structure of membrane microdomains restored the ability of NMDA receptors to disperse and internalize following gp120. These findings demonstrate that gp120 contributes to synaptic dysfunction in the setting of HIV-infection by interfering with the traffic of NMDA receptors. PMID:22114277

  1. NMDA Receptors in Clinical Neurology: Excitatory Times Ahead

    PubMed Central

    Kalia, Lorraine V.; Kalia, Suneil K.; Salter, Michael W.

    2013-01-01

    Since the N-methyl-D-aspartate receptor (NMDAR) subunits were first cloned less than two decades ago, a substantial amount of research has been invested into understanding the physiological function of NMDARs in the healthy CNS and their pathological roles in a variety of neurological diseases. These include conditions resulting from acute excitotoxic insults (e.g. ischemic stroke, traumatic brain injury), diseases due to chronic neurodegeneration (e.g. Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, amyotrophic lateral sclerosis), disorders arising from sensitization of neurons (e.g. epilepsy, neuropathic pain), as well as neurodevelopmental disorders associated with NMDAR hypofunction (e.g. schizophrenia). There has been much focus on selective NMDAR antagonists which have not produced positive results in clinical trials. However, there are other NMDAR-targeted therapies used in current practice which are effective for treating certain neurological disorders. In this review, we describe the evidence for the use of these therapies and provide an overview of drugs being investigated in clinical trials. We also discuss novel NMDAR-based strategies which are emerging in clinical neurology. PMID:18635022

  2. Role of NMDA receptors in acute liver failure and ammonia toxicity: therapeutical implications.

    PubMed

    Rodrigo, Regina; Cauli, Omar; Boix, Jordi; ElMlili, Nisrin; Agusti, Ana; Felipo, Vicente

    2009-01-01

    Acute liver failure (ALF) may lead to rapid death unless the patients receive a liver for transplantation. However, the number of livers available is not enough and a number of patients die before a suitable liver is available for transplantation. The liver has a high capacity for regeneration which may allow complete recovery even in patients with severe liver failure. It would be therefore very useful to have procedures to prevent or delay the mechanisms by which ALF leads to death. These mechanisms are no well understood. Progression of ALF leads to multi-organ failure, systemic inflammatory response, hepatic encephalopathy, cerebral oedema and increased intracranial pressure, which seem the most important immediate causes of mortality in patients with ALF. A main contributor to these events is hyperammonemia, due to impaired ammonia detoxification in the liver. Acute hyperammonemia per se leads to death, which is mediated by activation of the NMDA type of glutamate receptors in brain and may be prevented by antagonists blocking these receptors. Acute liver failure also leads to hyperammonemia and excessive activation of NMDA receptors in brain which contributes to ALF-induced death. Sustained blocking of NMDA receptors by continuous administration of the antagonists MK-801 or memantine increases about twice the survival time of rats with severe ALF due to injection of 2.5g/kg of galactosamine. In rats with milder ALF due to injection of 1.5g/kg of galactosamine, blocking NMDA receptors increases the percentage of surviving rats from 23% to 62% and increases about twice the survival time of the rats which die. These data strongly support that blocking NMDA receptors would improve survival of patients with ALF, either by allowing more time for liver regeneration or to get a liver suitable for transplantation. PMID:19428814

  3. Differential Modulation of Reinforcement Learning by D2 Dopamine and NMDA Glutamate Receptor Antagonism

    PubMed Central

    Klein, Tilmann A.; Ullsperger, Markus

    2014-01-01

    The firing pattern of midbrain dopamine (DA) neurons is well known to reflect reward prediction errors (PEs), the difference between obtained and expected rewards. The PE is thought to be a crucial signal for instrumental learning, and interference with DA transmission impairs learning. Phasic increases of DA neuron firing during positive PEs are driven by activation of NMDA receptors, whereas phasic suppression of firing during negative PEs is likely mediated by inputs from the lateral habenula. We aimed to determine the contribution of DA D2-class and NMDA receptors to appetitively and aversively motivated reinforcement learning. Healthy human volunteers were scanned with functional magnetic resonance imaging while they performed an instrumental learning task under the influence of either the DA D2 receptor antagonist amisulpride (400 mg), the NMDA receptor antagonist memantine (20 mg), or placebo. Participants quickly learned to select (“approach”) rewarding and to reject (“avoid”) punishing options. Amisulpride impaired both approach and avoidance learning, while memantine mildly attenuated approach learning but had no effect on avoidance learning. These behavioral effects of the antagonists were paralleled by their modulation of striatal PEs. Amisulpride reduced both appetitive and aversive PEs, while memantine diminished appetitive, but not aversive PEs. These data suggest that striatal D2-class receptors contribute to both approach and avoidance learning by detecting both the phasic DA increases and decreases during appetitive and aversive PEs. NMDA receptors on the contrary appear to be required only for approach learning because phasic DA increases during positive PEs are NMDA dependent, whereas phasic decreases during negative PEs are not. PMID:25253860

  4. Differential modulation of reinforcement learning by D2 dopamine and NMDA glutamate receptor antagonism.

    PubMed

    Jocham, Gerhard; Klein, Tilmann A; Ullsperger, Markus

    2014-09-24

    The firing pattern of midbrain dopamine (DA) neurons is well known to reflect reward prediction errors (PEs), the difference between obtained and expected rewards. The PE is thought to be a crucial signal for instrumental learning, and interference with DA transmission impairs learning. Phasic increases of DA neuron firing during positive PEs are driven by activation of NMDA receptors, whereas phasic suppression of firing during negative PEs is likely mediated by inputs from the lateral habenula. We aimed to determine the contribution of DA D2-class and NMDA receptors to appetitively and aversively motivated reinforcement learning. Healthy human volunteers were scanned with functional magnetic resonance imaging while they performed an instrumental learning task under the influence of either the DA D2 receptor antagonist amisulpride (400 mg), the NMDA receptor antagonist memantine (20 mg), or placebo. Participants quickly learned to select ("approach") rewarding and to reject ("avoid") punishing options. Amisulpride impaired both approach and avoidance learning, while memantine mildly attenuated approach learning but had no effect on avoidance learning. These behavioral effects of the antagonists were paralleled by their modulation of striatal PEs. Amisulpride reduced both appetitive and aversive PEs, while memantine diminished appetitive, but not aversive PEs. These data suggest that striatal D2-class receptors contribute to both approach and avoidance learning by detecting both the phasic DA increases and decreases during appetitive and aversive PEs. NMDA receptors on the contrary appear to be required only for approach learning because phasic DA increases during positive PEs are NMDA dependent, whereas phasic decreases during negative PEs are not. PMID:25253860

  5. New benzoyl urea derivatives as novel NR2B selective NMDA receptor antagonists.

    PubMed

    Borza, I; Greiner, I; Kolok, S; Galgóczy, K; Ignácz-Szendrei, Gy; Horváth, Cs; Farkas, S; Gáti, T; Háda, V; Domány, Gy

    2006-09-01

    A novel series of benzoyl urea derivatives was prepared and identified as NR2B selective NMDA receptor antagonists. The influence of the substitution of the piperidine ring on the biological activity of the compounds was studied. Compound 9 was active in the formalin test in mice. PMID:17020160

  6. Reconsolidation after Remembering an Odor-Reward Association Requires NMDA Receptors

    ERIC Educational Resources Information Center

    Torras-Garcia, Meritxell; Tronel, Sophie; Sara, Susan J.; Lelong, Julien

    2005-01-01

    A rapidly learned odor discrimination task based on spontaneous foraging behavior of the rat was used to evaluate the role of N-methyl-D-aspartate (NMDA) receptors (NMDARs) in ongoing memory consolidation. Rats were trained in a single session to discriminate among three odors, one of which was associated with palatable food reward. Previous…

  7. Differential Involvement of Amygdala and Cortical NMDA Receptors Activation upon Encoding in Odor Fear Memory

    ERIC Educational Resources Information Center

    Hegoburu, Chloé; Parrot, Sandrine; Ferreira, Guilaume; Mouly, Anne-Marie

    2014-01-01

    Although the basolateral amygdala (BLA) plays a crucial role for the acquisition of fear memories, sensory cortices are involved in their long-term storage in rats. However, the time course of their respective involvement has received little investigation. Here we assessed the role of the glutamatergic N-methyl-D-aspartate (NMDA) receptors in the…

  8. Involvement of ERK in NMDA receptor-independent cortical neurotoxicity of hydrogen sulfide

    SciTech Connect

    Kurokawa, Yuko; Sekiguchi, Fumiko; Kubo, Satoko; Yamasaki, Yoshiko; Matsuda, Sachi; Okamoto, Yukari; Sekimoto, Teruki; Fukatsu, Anna; Nishikawa, Hiroyuki; Kume, Toshiaki; Fukushima, Nobuyuki; Akaike, Akinori; Kawabata, Atsufumi

    2011-11-04

    Highlights: Black-Right-Pointing-Pointer Hydrogen sulfide causes NMDA receptor-independent neurotoxicity in mouse fetal cortical neurons. Black-Right-Pointing-Pointer Activation of ERK mediates the toxicity of hydrogen sulfide. Black-Right-Pointing-Pointer Apoptotic mechanisms are involved in the hydrogen-induced cell death. -- Abstract: Hydrogen sulfide (H{sub 2}S), a gasotransmitter, exerts both neurotoxicity and neuroprotection, and targets multiple molecules including NMDA receptors, T-type calcium channels and NO synthase (NOS) that might affect neuronal viability. Here, we determined and characterized effects of NaHS, an H{sub 2}S donor, on cell viability in the primary cultures of mouse fetal cortical neurons. NaHS caused neuronal death, as assessed by LDH release and trypan blue staining, but did not significantly reduce the glutamate toxicity. The neurotoxicity of NaHS was resistant to inhibitors of NMDA receptors, T-type calcium channels and NOS, and was blocked by inhibitors of MEK, but not JNK, p38 MAP kinase, PKC and Src. NaHS caused prompt phosphorylation of ERK and upregulation of Bad, followed by translocation of Bax to mitochondria and release of mitochondrial cytochrome c, leading to the nuclear condensation/fragmentation. These effects of NaHS were suppressed by the MEK inhibitor. Our data suggest that the NMDA receptor-independent neurotoxicity of H{sub 2}S involves activation of the MEK/ERK pathway and some apoptotic mechanisms.

  9. Inhibition of Acetylcholinesterase Modulates NMDA Receptor Antagonist Mediated Alterations in the Developing Brain

    PubMed Central

    Bendix, Ivo; Serdar, Meray; Herz, Josephine; von Haefen, Clarissa; Nasser, Fatme; Rohrer, Benjamin; Endesfelder, Stefanie; Felderhoff-Mueser, Ursula; Spies, Claudia D.; Sifringer, Marco

    2014-01-01

    Exposure to N-methyl-d-aspartate (NMDA) receptor antagonists has been demonstrated to induce neurodegeneration in newborn rats. However, in clinical practice the use of NMDA receptor antagonists as anesthetics and sedatives cannot always be avoided. The present study investigated the effect of the indirect cholinergic agonist physostigmine on neurotrophin expression and the extracellular matrix during NMDA receptor antagonist induced injury to the immature rat brain. The aim was to investigate matrix metalloproteinase (MMP)-2 activity, as well as expression of tissue inhibitor of metalloproteinase (TIMP)-2 and brain-derived neurotrophic factor (BDNF) after co-administration of the non-competitive NMDA receptor antagonist MK801 (dizocilpine) and the acetylcholinesterase (AChE) inhibitor physostigmine. The AChE inhibitor physostigmine ameliorated the MK801-induced reduction of BDNF mRNA and protein levels, reduced MK801-triggered MMP-2 activity and prevented decreased TIMP-2 mRNA expression. Our results indicate that AChE inhibition may prevent newborn rats from MK801-mediated brain damage by enhancing neurotrophin-associated signaling pathways and by modulating the extracellular matrix. PMID:24595240

  10. NMDA and non-NMDA glutamate receptors in the paraventricular nucleus of the hypothalamus modulate different stages of hemorrhage-evoked cardiovascular responses in rats.

    PubMed

    Busnardo, C; Crestani, C C; Fassini, A; Resstel, L B M; Corrêa, F M A

    2016-04-21

    Here we report the involvement of N-Methyl-d-Aspartate (NMDA) and non-NMDA glutamate receptors from the paraventricular nucleus of the hypothalamus (PVN) in the mediation of cardiovascular changes observed during hemorrhage and post-bleeding periods. In addition, the present study provides further evidence of the involvement of circulating vasopressin and cardiac sympathetic activity in cardiovascular responses to hemorrhage. Systemic treatment with the V1-vasopressin receptor antagonist dTyr(CH2)5(Me)AVP (50 μg/kg, i.v.) increased the latency to the onset of hypotension during hemorrhage and slowed post-bleeding recovery of blood pressure. Systemic treatment with the β1-adrenergic receptor antagonist atenolol (1 mg/kg, i.v.) also increased the latency to the onset of hypotension during hemorrhage. Moreover, atenolol reversed the hemorrhage-induced tachycardia into bradycardia. Bilateral microinjection of the selective NMDA glutamate receptor antagonist LY235959 (2 nmol/100 nL) into the PVN blocked the hypotensive response to hemorrhage and reduced the tachycardia during the post-hemorrhage period. Systemic treatment with dTyr(CH2)5(Me)AVP inhibited the effect of LY235959 on hemorrhage-induced hypotension, without affecting the post-bleeding tachycardia. PVN treatment with the selective non-NMDA receptor antagonist NBQX (2 nmol/100 nL) reduced the recovery of blood pressure to normal levels in the post-bleeding phase and reduced hemorrhage-induced tachycardia. Combined blockade of both NMDA and non-NMDA glutamate receptors in the PVN completely abolished the hypotensive response in the hemorrhage period and reduced the tachycardiac response in the post-hemorrhage period. These results indicate that local PVN glutamate neurotransmission is involved in the neural pathway mediating cardiovascular responses to hemorrhage, via an integrated control involving autonomic nervous system activity and vasopressin release into the circulation. PMID:26861418

  11. Short-term sleep deprivation impairs spatial working memory and modulates expression levels of ionotropic glutamate receptor subunits in hippocampus.

    PubMed

    Xie, Meilan; Yan, Jie; He, Chao; Yang, Li; Tan, Gang; Li, Chao; Hu, Zhian; Wang, Jiali

    2015-06-01

    Hippocampus-dependent learning memory is sensitive to sleep deprivation (SD). Although the ionotropic glutamate receptors play a vital role in synaptic plasticity and learning and memory, however, whether the expression of these receptor subunits is modulated by sleep loss remains unclear. In the present study, western blotting was performed by probing with specific antibodies against the ionotropic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor subunits GluA1, GluA2, GluA3, and against the N-methyl-d-aspartate (NMDA) glutamate receptor subunits GluN1, GluN2A, GluN2B. In hippocampus, down regulation of surface GluA1 and GluN2A surface expression were observed in both SD groups. However, surface expression level of GluA2, GluA3, GluN1 and GluN2B was significantly up-regulated in 8h-SD rats when compared to the 4h-SD rats. In parallel with the complex changes in AMPA and NMDA receptor subunit expressions, we found the 8h-SD impaired rat spatial working memory in 30-s-delay T-maze task, whereas no impairment of spatial learning was observed in 4h-SD rats. These results indicate that sleep loss alters the relative expression levels of the AMPA and NMDA receptors, thus affects the synaptic strength and capacity for plasticity and partially contributes to spatial memory impairment. PMID:25732956

  12. Recent Progress in Understanding Subtype Specific Regulation of NMDA Receptors by G Protein Coupled Receptors (GPCRs)

    PubMed Central

    Yang, Kai; Jackson, Michael F.; MacDonald, John F.

    2014-01-01

    G Protein Coupled Receptors (GPCRs) are the largest family of receptors whose ligands constitute nearly a third of prescription drugs in the market. They are widely involved in diverse physiological functions including learning and memory. NMDA receptors (NMDARs), which belong to the ionotropic glutamate receptor family, are likewise ubiquitously expressed in the central nervous system (CNS) and play a pivotal role in learning and memory. Despite its critical contribution to physiological and pathophysiological processes, few pharmacological interventions aimed directly at regulating NMDAR function have been developed to date. However, it is well established that NMDAR function is precisely regulated by cellular signalling cascades recruited downstream of G protein coupled receptor (GPCR) stimulation. Accordingly, the downstream regulation of NMDARs likely represents an important determinant of outcome following treatment with neuropsychiatric agents that target selected GPCRs. Importantly, the functional consequence of such regulation on NMDAR function varies, based not only on the identity of the GPCR, but also on the cell type in which relevant receptors are expressed. Indeed, the mechanisms responsible for regulating NMDARs by GPCRs involve numerous intracellular signalling molecules and regulatory proteins that vary from one cell type to another. In the present article, we highlight recent findings from studies that have uncovered novel mechanisms by which selected GPCRs regulate NMDAR function and consequently NMDAR-dependent plasticity. PMID:24562329

  13. Knockdown of BNST GluN2B-containing NMDA receptors mimics the actions of ketamine on novelty-induced hypophagia

    PubMed Central

    Louderback, K M; Wills, T A; Muglia, L J; Winder, D G

    2013-01-01

    Administration of a single low dose of the N-methyl-D-aspartate (NMDA) receptor antagonist ketamine has been demonstrated to elicit long-lasting antidepressant effects in humans with depression, as well as in rodent models of depression. Although pharmacological studies have implicated the GluN2B subunit of the NMDA receptor in these effects, drugs targeting this subunit have off-target actions, and systemic administration of these compounds does not allow for delineation of specific brain regions involved. In this study, we assessed the role of GluN2B in the bed nucleus of the stria terminalis (BNST) in novelty-induced hypophagia (NIH) in mice. First, we verified that ketamine, as well as the GluN2B antagonist Ro25–6981, decreased the latency to consume food in a novel environment in a version of the NIH test. We then hypothesized that GluN2B-containing receptors within the BNST may be a target of systemic ketamine and contribute to behavioral effects. Through the combination of a GluN2B-floxed mouse line and stereotaxic delivery of lentiviral Cre recombinase, we found that targeted knockdown of this subunit within the BNST mimicked the reduction in affective behavior observed with systemic ketamine or Ro25–6981 in the NIH test. These data suggest a role for GluN2B-containing NMDARs within the BNST in the affective effects of systemic ketamine. PMID:24301649

  14. Expression of specific ionotropic glutamate and GABA-A receptor subunits is decreased in central amygdala of alcoholics

    PubMed Central

    Jin, Zhe; Bhandage, Amol K.; Bazov, Igor; Kononenko, Olga; Bakalkin, Georgy; Korpi, Esa R.; Birnir, Bryndis

    2014-01-01

    The central amygdala (CeA) has a role for mediating fear and anxiety responses. It is also involved in emotional imbalance caused by alcohol abuse and dependence and in regulating relapse to alcohol abuse. Growing evidences suggest that excitatory glutamatergic and inhibitory γ-aminobutyric acid-ergic (GABAergic) transmissions in the CeA are affected by chronic alcohol exposure. Human post-mortem CeA samples from male alcoholics (n = 9) and matched controls (n = 9) were assayed for the expression level of ionotropic glutamate and GABA-A receptors subunit mRNAs using quantitative real-time reverse transcription-PCR (RT-qPCR). Our data revealed that out of the 16 ionotropic glutamate receptor subunits, mRNAs encoding two AMPA [2-amino-3-(3-hydroxy-5-methyl-isoxazol-4-yl)propanoic acid] receptor subunits GluA1 and GluA4; one kainate receptor subunit GluK2; one NMDA (N-methyl-D-aspartate) receptor subunit GluN2D and one delta receptor subunit GluD2 were significantly decreased in the CeA of alcoholics. In contrast, of the 19 GABA-A receptor subunits, only the mRNA encoding the α2 subunit was significantly down-regulated in the CeA of the alcoholics as compared with control subjects. Our findings imply that the down-regulation of specific ionotropic glutamate and GABA-A receptor subunits in the CeA of alcoholics may represent one of the molecular substrates underlying the new balance between excitatory and inhibitory neurotransmission in alcohol dependence. PMID:25278838

  15. NMDA receptors are the basis for persistent network activity in neocortex slices

    PubMed Central

    Favero, Morgana

    2015-01-01

    During behavioral quiescence the neocortex generates spontaneous slow oscillations that consist of Up and Down states. Up states are short epochs of persistent activity, but their underlying source is unclear. In neocortex slices of adult mice, we monitored several cellular and network variables during the transition between a traditional buffer, which does not cause Up states, and a lower-divalent cation buffer, which leads to the generation of Up states. We found that the resting membrane potential and input resistance of cortical cells did not change with the development of Up states. The synaptic efficacy of excitatory postsynaptic potentials mediated by non-NMDA receptors was slightly reduced, but this is unlikely to facilitate the generation of Up states. On the other hand, we identified two variables that are associated with the generation of Up states: an enhancement of the intrinsic firing excitability of cortical cells and an enhancement of NMDA-mediated responses evoked by electrical or optogenetic stimulation. The fact that blocking NMDA receptors abolishes Up states indicates that the enhancement in intrinsic firing excitability alone is insufficient to generate Up states. NMDA receptors have a crucial role in the generation of Up states in neocortex slices. PMID:25878152

  16. Mutations in GABAA receptor subunits associated with genetic epilepsies.

    PubMed

    Macdonald, Robert L; Kang, Jing-Qiong; Gallagher, Martin J

    2010-06-01

    Mutations in inhibitory GABAA receptor subunit genes (GABRA1, GABRB3, GABRG2 and GABRD) have been associated with genetic epilepsy syndromes including childhood absence epilepsy (CAE), juvenile myoclonic epilepsy (JME), pure febrile seizures (FS), generalized epilepsy with febrile seizures plus (GEFS+), and Dravet syndrome (DS)/severe myoclonic epilepsy in infancy (SMEI). These mutations are found in both translated and untranslated gene regions and have been shown to affect the GABAA receptors by altering receptor function and/or by impairing receptor biogenesis by multiple mechanisms including reducing subunit mRNA transcription or stability, impairing subunit folding, stability, or oligomerization and by inhibiting receptor trafficking. PMID:20308251

  17. Modulation of NMDA receptor function by inhibition of D-amino acid oxidase in rodent brain.

    PubMed

    Strick, Christine A; Li, Cheryl; Scott, Liam; Harvey, Brian; Hajós, Mihály; Steyn, Stefanus J; Piotrowski, Mary A; James, Larry C; Downs, James T; Rago, Brian; Becker, Stacey L; El-Kattan, Ayman; Xu, Youfen; Ganong, Alan H; Tingley, F David; Ramirez, Andres D; Seymour, Patricia A; Guanowsky, Victor; Majchrzak, Mark J; Fox, Carol B; Schmidt, Christopher J; Duplantier, Allen J

    2011-01-01

    Observations that N-Methyl-D-Aspartate (NMDA) antagonists produce symptoms in humans that are similar to those seen in schizophrenia have led to the current hypothesis that schizophrenia might result from NMDA receptor hypofunction. Inhibition of D-amino acid oxidase (DAAO), the enzyme responsible for degradation of D-serine, should lead to increased levels of this co-agonist at the NMDA receptor, and thereby provide a therapeutic approach to schizophrenia. We have profiled some of the preclinical biochemical, electrophysiological, and behavioral consequences of administering potent and selective inhibitors of DAAO to rodents to begin to test this hypothesis. Inhibition of DAAO activity resulted in a significant dose and time dependent increase in D-serine only in the cerebellum, although a time delay was observed between peak plasma or brain drug concentration and cerebellum D-serine response. Pharmacokinetic/pharmacodynamic (PK/PD) modeling employing a mechanism-based indirect response model was used to characterize the correlation between free brain drug concentration and D-serine accumulation. DAAO inhibitors had little or no activity in rodent models considered predictive for antipsychotic activity. The inhibitors did, however, affect cortical activity in the Mescaline-Induced Scratching model, produced a modest but significant increase in NMDA receptor-mediated synaptic currents in primary neuronal cultures from rat hippocampus, and resulted in a significant increase in evoked hippocampal theta rhythm, an in vivo electrophysiological model of hippocampal activity. These findings demonstrate that although DAAO inhibition did not cause a measurable increase in D-serine in forebrain, it did affect hippocampal and cortical activity, possibly through augmentation of NMDA receptor-mediated currents. PMID:21763704

  18. Heterogeneity of clinical features and corresponding antibodies in seven patients with anti-NMDA receptor encephalitis

    PubMed Central

    SÜHS, KURT-WOLFRAM; WEGNER, FLORIAN; SKRIPULETZ, THOMAS; TREBST, CORINNA; TAYEB, SAID BEN; RAAB, PETER; STANGEL, MARTIN

    2015-01-01

    Anti-N-methyl D-aspartate (NMDA) receptor encephalitis is the most common type of encephalitis in the spectrum of autoimmune encephalitis defined by antibodies targeting neuronal surface antigens. In the present study, the clinical spectrum of this disease is presented using instructive cases in correlation with the anti-NMDA receptor antibody titers in the cerebrospinal fluid (CSF) and serum. A total of 7 female patients admitted to the hospital of Hannover Medical School (Hannover, Germany) between 2008 and 2014 were diagnosed with anti-NMDA receptor encephalitis. Among these patients, 3 cases were selected to illustrate the range of similar and distinct clinical features across the spectrum of the disease and to compare anti-NMDA antibody levels throughout the disease course. All patients received immunosuppressive treatment with methylprednisolone, intravenous immunoglobulin and/or plasmapheresis, followed in the majority of patients by second-line therapy with rituximab and cyclophosphamide. The disease course correlated with NMDA receptor antibody titers, and to a greater extent with the ratio between antibody titer and protein concentration. A favorable clinical outcome with a modified Rankin Scale (mRS) score of ≤1 was achieved in 4 patients, 1 patient had an mRS score of 2 after 3 months of observation only, whereas 2 patients remained severely impaired (mRS score 4). Early and aggressive immunosuppressive treatment appears to support a good clinical outcome; however, the clinical signs and symptoms differ distinctively and treatment decisions have to be made on an individual basis. PMID:26622479

  19. Nuclear respiratory factor 2 regulates the transcription of AMPA receptor subunit GluA2 (Gria2).

    PubMed

    Priya, Anusha; Johar, Kaid; Nair, Bindu; Wong-Riley, Margaret T T

    2014-12-01

    Neuronal activity is highly dependent on energy metabolism. Nuclear respiratory factor 2 (NRF-2) tightly couples neuronal activity and energy metabolism by transcriptionally co-regulating all 13 subunits of an important energy-generating enzyme, cytochrome c oxidase (COX), as well as critical subunits of excitatory NMDA receptors. AMPA receptors are another major class of excitatory glutamatergic receptors that mediate most of the fast excitatory synaptic transmission in the brain. They are heterotetrameric proteins composed of various combinations of GluA1-4 subunits, with GluA2 being the most common one. We have previously shown that GluA2 (Gria2) is transcriptionally regulated by nuclear respiratory factor 1 (NRF-1) and specificity protein 4 (Sp4), which also regulate all subunits of COX. However, it was not known if NRF-2 also couples neuronal activity and energy metabolism by regulating subunits of the AMPA receptors. By means of multiple approaches, including electrophoretic mobility shift and supershift assays, chromatin immunoprecipitation, promoter mutations, real-time quantitative PCR, and western blot analysis, NRF-2 was found to functionally regulate the expression of Gria2, but not of Gria1, Gria3, or Gria4 genes in neurons. By regulating the GluA2 subunit of the AMPA receptor, NRF-2 couples energy metabolism and neuronal activity at the transcriptional level through a concurrent and parallel mechanism with NRF-1 and Sp4. PMID:25245478

  20. Quantifying the cooperative subunit action in a multimeric membrane receptor

    PubMed Central

    Wongsamitkul, Nisa; Nache, Vasilica; Eick, Thomas; Hummert, Sabine; Schulz, Eckhard; Schmauder, Ralf; Schirmeyer, Jana; Zimmer, Thomas; Benndorf, Klaus

    2016-01-01

    In multimeric membrane receptors the cooperative action of the subunits prevents exact knowledge about the operation and the interaction of the individual subunits. We propose a method that permits quantification of ligand binding to and activation effects of the individual binding sites in a multimeric membrane receptor. The power of this method is demonstrated by gaining detailed insight into the subunit action in olfactory cyclic nucleotide-gated CNGA2 ion channels. PMID:26858151

  1. NMDA receptor desensitization regulated by direct binding to PDZ1-2 domains of PSD-95

    PubMed Central

    Sornarajah, Lavan; Vasuta, Oana Cristina; Zhang, Lily; Sutton, Christine; Li, Bo; El-Husseini, Alaa; Raymond, Lynn A.

    2010-01-01

    Regulation of NMDA receptor (NMDAR) activity by desensitization is important in physiological and pathological states; NMDAR desensitization contributes in shaping synaptic responses and may be protective by limiting calcium influx during sustained glutamate insults. We previously reported that glycine-independent desensitization decreases during hippocampal neuronal development, correlating with NMDAR synaptic localization and association with post-synaptic density 95 (PSD-95). PSD-95/Discs large/zona occludens (PDZ)-1,2 domains of PSD-95 bind to the C-terminus of NMDAR NR2 subunits. The role of PSD-95 in anchoring signaling proteins near NMDARs is well documented. To determine if PSD-95-induced changes in NMDAR desensitization occur because of direct binding to NR2 or due to recruitment of regulatory proteins, we tested the effects of various PSD-95 constructs on NMDAR currents in human embryonic kidney 293 (HEK293) cells and neurons. In HEK cells, wild-type PSD-95 significantly reduced wild-type NMDAR desensitization without altering currents of NMDARs containing NR2A-S1462A, a mutation that abolishes PSD-95 binding. The PSD-95 N-terminus truncated after the PDZ1-2 domains was sufficient for this effect in neurons with low endogenous PSD-95 levels; in NMDAR-expressing HEK cells, the effect persisted when PSD-95 multimerization was eliminated. Moreover, other PSD-95 family members with highly homologous PDZ1-2 domains significantly reduced NMDAR desensitization. In mature neurons, disruption of PSD-95/NMDAR interaction through protein kinase C (PKC) activation increased desensitization to levels found in immature neurons, and this effect was not due to PKC direct regulation of NMDAR activity. We conclude that direct binding of PSD-95 increases stability of NMDAR responses to agonist exposure in neuronal and non-neuronal cells. PMID:18400955

  2. Polygalasaponin F induces long-term potentiation in adult rat hippocampus via NMDA receptor activation

    PubMed Central

    Sun, Feng; Sun, Jian-dong; Han, Ning; Li, Chuang-jun; Yuan, Yu-he; Zhang, Dong-ming; Chen, Nai-hong

    2012-01-01

    Aim: To investigate the effect and underlying mechanisms of polygalasaponin F (PGSF), a triterpenoid saponin isolated from Polygala japonica, on long-term potentiation (LTP) in hippocampus dentate gyrus (DG) of anesthetized rats. Methods: Population spike (PS) of hippocampal DG was recorded in anesthetized male Wistar rats. PGSF, the NMDAR inhibitor MK801 and the CaMKII inhibitor KN93 were intracerebroventricularly administered. Western blotting analysis was used to examine the phosphorylation expressions of NMDA receptor subunit 2B (NR2B), Ca2+/calmodulin-dependent kinase II (CaMKII), extracellular signal-regulated kinase (ERK), and cAMP response element-binding protein (CREB). Results: Intracerebroventricular administration of PGSF (1 and 10 μmol/L) produced long-lasting increase of PS amplitude in hippocampal DG in a dose-dependent manner. Pre-injection of MK801 (100 μmol/L) or KN93 (100 μmol/L) completely blocked PGSF-induced LTP. Furthermore, the phosphorylation of NR2B, CaMKII, ERK, and CREB in hippocampus was significantly increased 5–60 min after LTP induction. The up-regulation of p-CaMKII expression could be completely abolished by pre-injection of MK801. The up-regulation of p-ERK and p-CREB expressions could be partially blocked by pre-injection of KN93. Conclusion: PGSF could induce LTP in hippocampal DG in anesthetized rats via NMDAR activation mediated by CaMKII, ERK and CREB signaling pathway. PMID:22286914

  3. Frequency-dependent facilitation of synaptic throughput via postsynaptic NMDA receptors in the nucleus of the solitary tract.

    PubMed

    Zhao, Huan; Peters, James H; Zhu, Mingyan; Page, Stephen J; Ritter, Robert C; Appleyard, Suzanne M

    2015-01-01

    Hindbrain NMDA receptors play important roles in reflexive and behavioural responses to vagal activation. NMDA receptors have also been shown to contribute to the synaptic responses of neurons in the nucleus of the solitary tract (NTS), but their exact role remains unclear. In this study we used whole cell patch-clamping techniques in rat horizontal brain slice to investigate the role of NMDA receptors in the fidelity of transmission across solitary tract afferent-NTS neuron synapses. Results show that NMDA receptors contribute up to 70% of the charge transferred across the synapse at high (>5 Hz) firing rates, but have little contribution at lower firing frequencies. Results also show that NMDA receptors critically contribute to the fidelity of transmission across these synapses during high frequency (>5 Hz) afferent discharge rates. This novel role of NMDA receptors may explain in part how primary visceral afferents, including vagal afferents, can maintain fidelity of transmission across a broad range of firing frequencies. Neurons within the nucleus of the solitary tract (NTS) receive vagal afferent innervations that initiate gastrointestinal and cardiovascular reflexes. Glutamate is the fast excitatory neurotransmitter released in the NTS by vagal afferents, which arrive there via the solitary tract (ST). ST stimulation elicits excitatory postsynaptic currents (EPSCs) in NTS neurons mediated by both AMPA- and NMDA-type glutamate receptors (-Rs). Vagal afferents exhibit a high probability of vesicle release and exhibit robust frequency-dependent depression due to presynaptic vesicle depletion. Nonetheless, synaptic throughput is maintained even at high frequencies of afferent activation. Here we test the hypothesis that postsynaptic NMDA-Rs are essential in maintaining throughput across ST-NTS synapses. Using patch clamp electrophysiology in horizontal brainstem slices, we found that NMDA-Rs, including NR2B subtypes, carry up to 70% of the charge transferred

  4. Phrenic long-term facilitation requires NMDA receptors in the phrenic motonucleus in rats

    PubMed Central

    McGuire, Michelle; Zhang, Yi; White, David P; Ling, Liming

    2005-01-01

    Exposure to episodic hypoxia induces a persistent augmentation of respiratory activity, known as long-term facilitation (LTF). LTF of phrenic nerve activity has been reported to require serotonin receptor activation and protein syntheses. However, the underlying cellular mechanism still remains poorly understood. NMDA receptors play key roles in synaptic plasticity (e.g. some forms of hippocampal long-term potentiation). The present study was designed to examine the role of NMDA receptors in phrenic LTF and test if the relevant receptors are located in the phrenic motonucleus. Integrated phrenic nerve activity was measured in anaesthetized, vagotomized, neuromuscularly blocked and artificially ventilated rats before, during and after three episodes of 5 min isocapnic hypoxia (Pa,O2= 30–45 mmHg), separated by 5 min hyperoxia (50% O2). Either saline (as control) or the NMDA receptor antagonist MK-801 (0.2 mg kg−1, i.p.) was systemically injected ∼1 h before hypoxia. Phrenic LTF was eliminated by the MK-801 injection (vehicle, 32.8 ± 3.7% above baseline in phrenic amplitude at 60 min post-hypoxia; MK-801, −0.5 ± 4.1%, means ± s.e.m.), with little change in both the CO2-apnoeic threshold and the hypoxic phrenic response (HPR). Vehicle (saline, 5 × 100 nl) or MK-801 (10 μm; 5 × 100 nl) was also microinjected into the phrenic motonucleus region in other groups. Phrenic LTF was eliminated by the MK-801 microinjection (vehicle, 34.2 ± 3.4%; MK-801, −2.5 ± 2.8%), with minimal change in HPR. Collectively, these results suggest that the activation of NMDA receptors in the phrenic motonucleus is required for the episodic hypoxia-induced phrenic LTF. PMID:15932891

  5. GluN2B-selective N-methyl-D-aspartate (NMDA) receptor antagonists derived from 3-benzazepines: synthesis and pharmacological evaluation of benzo[7]annulen-7-amines.

    PubMed

    Benner, Andre; Bonifazi, Alessandro; Shirataki, Chikako; Temme, Louisa; Schepmann, Dirk; Quaglia, Wilma; Shoji, Osami; Watanabe, Yoshihito; Daniliuc, Constantin; Wünsch, Bernhard

    2014-04-01

    Given their high neuroprotective potential, ligands that block GluN2B-containing N-methyl-D-aspartate (NMDA) receptors by interacting with the ifenprodil binding site located on the GluN2B subunit are of great interest for the treatment of various neuronal disorders. In this study, a novel class of GluN2B-selective NMDA receptor antagonists with the benzo[7]annulene scaffold was prepared and pharmacologically evaluated. The key intermediate, N-(2-methoxy-5-oxo-6,7,8,9-tetrahydro-5H-benzo[7]annulen-7-yl)acetamide (11), was obtained by cyclization of 3-acetamido-5-(3-methoxyphenyl)pentanoic acid (10 b). The final reaction steps comprise hydrolysis of the amide, reduction of the ketone, and reductive alkylation, leading to cis- and trans-configured 7-(ω-phenylalkylamino)benzo[7]annulen-5-ols. High GluN2B affinity was observed with cis-configured γ-amino alcohols substituted with a 3-phenylpropyl moiety at the amino group. Removal of the benzylic hydroxy moiety led to the most potent GluN2B antagonists of this series: 2-methoxy-N-(3-phenylpropyl)-6,7,8,9-tetrahydro-5H-benzo[7]annulen-7-amine (20 a, Ki =10 nM) and 2-methoxy-N-methyl-N-(3-phenylpropyl)-6,7,8,9-tetrahydro-5H-benzo[7]annulen-7-amine (23 a, Ki =7.9 nM). The selectivity over related receptors (phencyclidine binding site of the NMDA receptor, σ1 and σ2 receptors) was recorded. In a functional assay measuring the cytoprotective activity of the benzo[7]annulenamines, all tested compounds showed potent NMDA receptor antagonistic activity. Cytotoxicity induced via GluN2A subunit-containing NMDA receptors was not inhibited by the new ligands. PMID:24677663

  6. Age-related hearing loss: GABA, nicotinic acetylcholine and NMDA receptor expression changes in spiral ganglion neurons of the mouse.

    PubMed

    Tang, X; Zhu, X; Ding, B; Walton, J P; Frisina, R D; Su, J

    2014-02-14

    Age-related hearing loss - presbycusis - is the number one communication disorder and most prevalent neurodegenerative condition of our aged population. Although speech understanding in background noise is quite difficult for those with presbycusis, there are currently no biomedical treatments to prevent, delay or reverse this condition. A better understanding of the cochlear mechanisms underlying presbycusis will help lead to future treatments. Objectives of the present study were to investigate GABAA receptor subunit α1, nicotinic acetylcholine (nACh) receptor subunit β2, and N-methyl-d-aspartate (NMDA) receptor subunit NR1 mRNA and protein expression changes in spiral ganglion neurons (SGN) of the CBA/CaJ mouse cochlea, that occur in age-related hearing loss, utilizing quantitative immunohistochemistry and semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) techniques. We found that auditory brainstem response (ABR) thresholds shifted over 40dB from 3 to 48kHz in old mice compared to young adults. DPOAE thresholds also shifted over 40dB from 6 to 49kHz in old mice, and their amplitudes were significantly decreased or absent in the same frequency range. SGN density decreased with age in basal, middle and apical turns, and SGN density of the basal turn declined the most. A positive correlation was observed between SGN density and ABR wave 1amplitude. mRNA and protein expression of GABAAR α1 and AChR β2 decreased with age in SGNs in the old mouse cochlea. mRNA and protein expression of NMDAR NR1 increased with age in SGNs of the old mice. These findings demonstrate that there are functionally-relevant age-related changes of GABAAR, nAChR, NMDAR expression in CBA mouse SGNs reflecting their degeneration, which may be related to functional changes in cochlear synaptic transmission with age, suggesting biological mechanisms for peripheral age-related hearing loss. PMID:24316061

  7. Experience-Dependent Changes in Excitatory and Inhibitory Receptor Subunit Expression in Visual Cortex

    PubMed Central

    Beston, Brett R.; Jones, David G.; Murphy, Kathryn M.

    2010-01-01

    Experience-dependent development of visual cortex depends on the balance between excitatory and inhibitory activity. This activity is regulated by key excitatory (NMDA, AMPA) and inhibitory (GABAA) receptors. The composition of these receptors changes developmentally, affecting the excitatory–inhibitory (E/I) balance and synaptic plasticity. Until now, it has been unclear how abnormal visual experience affects this balance. To examine this question, we measured developmental changes in excitatory and inhibitory receptor subunits in visual cortex following normal visual experience and monocular deprivation. We used Western blot analysis to quantify expression of excitatory (NR1, NR2A, NR2B, GluR2) and inhibitory (GABAAα1, GABAAα3) receptor subunits. Monocular deprivation promoted a complex pattern of changes in receptor subunit expression that varied with age and was most severe in the region of visual cortex representing the central visual field. To characterize the multidimensional pattern of experience-dependent change in these synaptic mechanisms, we applied a neuroinformatics approach using principal component analysis. We found that monocular deprivation (i) causes a large portion of the normal developmental trajectory to be bypassed, (ii) shifts the E/I balance in favor of more inhibition, and (iii) accelerates the maturation of receptor subunits. Taken together, these results show that monocularly deprived animals have an abnormal balance of the synaptic machinery needed for functional maturation of cortical circuits and for developmental plasticity. This raises the possibility that interventions intended to treat amblyopia may need to address multiple synaptic mechanisms to produce optimal recovery. PMID:21423524

  8. Genetic NMDA receptor deficiency disrupts acute and chronic effects of cocaine but not amphetamine.

    PubMed

    Ramsey, Amy J; Laakso, Aki; Cyr, Michel; Sotnikova, Tatyana D; Salahpour, Ali; Medvedev, Ivan O; Dykstra, Linda A; Gainetdinov, Raul R; Caron, Marc G

    2008-10-01

    NMDA receptor-mediated glutamate transmission is required for several forms of neuronal plasticity. Its role in the neuronal responses to addictive drugs is an ongoing subject of investigation. We report here that the acute locomotor-stimulating effect of cocaine is absent in NMDA receptor-deficient mice (NR1-KD). In contrast, their acute responses to amphetamine and to direct dopamine receptor agonists are not significantly altered. The striking attenuation of cocaine's acute effects is not likely explained by alterations in the dopaminergic system of NR1-KD mice, since most parameters of pre- and postsynaptic dopamine function are unchanged. Consistent with the behavioral findings, cocaine induces less c-Fos expression in the striatum of these mice, while amphetamine-induced c-Fos expression is intact. Furthermore, chronic cocaine-induced sensitization and conditioned place preference are attenuated and develop more slowly in mutant animals, but amphetamine's effects are not altered significantly. Our results highlight the importance of NMDA receptor-mediated glutamatergic transmission specifically in cocaine actions, and support a hypothesis that cocaine and amphetamine elicit their effects through differential actions on signaling pathways. PMID:18185498

  9. Abnormal dephosphorylation effect on NMDA receptor regulation in ALS spinal cord.

    PubMed

    Wagey, R; Krieger, C; Shaw, C A

    1997-01-01

    Previous studies have demonstrated a significant reduction of N-methyl-D-aspartate (NMDA) receptor binding in spinal cord sections from patients who died with amyotrophic lateral sclerosis (ALS) compared to that in control patients. The reduction in NMDA receptor binding in ALS could be increased toward control values by treatment with phorbol ester, suggesting a role for receptor protein phosphorylation in this disorder. In the present study we have evaluated the time course of recovery of [3H]MK-801 binding following phorbol ester treatment to assess protein phosphatase activity in spinal cord sections from ALS and control subjects. Phorbol ester-stimulated changes in [3H]MK-801 binding returned to untreated values significantly faster in ALS tissue compared to control and could not be blocked by the coapplication of the protein phosphatase inhibitors sodium vanadate or sodium beta-D-glycerol phosphate. Okadaic acid coapplication blocked recovery in both ALS and control tissue at a concentration range at which phosphatase 2B (calcineurin) would likely be inhibited. The results suggest that abnormal levels or activity of protein phosphatases, including calcineurin, may be involved in the abnormal levels of NMDA receptors in ALS and may play some role in the pathogenesis of the disease. PMID:9440123

  10. Age- and Hormone-Regulation of N-Methyl-d-Aspartate Receptor Subunit NR2b in the Anteroventral Periventricular Nucleus of the Female Rat

    PubMed Central

    Maffucci, J. A.; Noel, M. L.; Gillette, R.; Wu, D.; Gore, A. C.

    2009-01-01

    Glutamate, acting through its N-methyl-d-aspartate (NMDA) and non-NMDA receptors in the hypothalamus, regulates reproductive neuroendocrine functions via direct and indirect actions upon gonadotrophin-releasing hormone (GnRH) neurones. Previous studies indicate that the NMDA receptor subunit NR2b undergoes changes in protein and gene expression in the hypothalamus in general, and on GnRH neurones in particular, during reproductive ageing. In the present study, we examined whether the NR2b-expressing cell population, both alone and in association with the NR1 subunit (i.e. the latter subunit is necessary for a functional NMDA receptor), is altered as a function of age and/or steroid hormone treatment. Studies focused on the anteroventral periventricular (AVPV) nucleus of the hypothalamus, a region critically involved in the control of reproduction. Young (3-5 months), middle-aged (9-12 months), and aged (approximately 22 months) female rats were ovariectomised and, 1 month later, they were treated sequentially with oestradiol plus progesterone, oestradiol plus vehicle, or vehicle plus vehicle, then perfused. Quantitative stereologic analysis of NR2b-immunoreactive cell numbers in the AVPV showed an age-associated decrease in the density of NR2b-immunoreactive cells, but no effect of hormone treatment. In a second study, immunofluorescent double labelling of NR2b and NR1 was analysed by confocal microscopy of fraction volume, a semi-quantitative measure of fluorescence intensity. No effect of ageing was detected for immunofluorescent NR1 or NR2b alone, whereas the NR2b fraction volume increased in the oestradiol plus vehicle group. With ageing, the fraction volume of the NR2b/NR1-colocalised subunits increased. Together with the stereology results, this suggests that, although fewer cells express the NR2b subunit in the ageing AVPV, a greater percentage of these subunits are co-expressed with NR1. Our results suggest that the subunit composition of NMDA receptors in

  11. A novel substituted aminoquinoline selectively targets voltage-sensitive sodium channel isoforms and NMDA receptor subtypes and alleviates chronic inflammatory and neuropathic pain.

    PubMed

    Tabakoff, Boris; Ren, Wenhua; Vanderlinden, Lauren; Snell, Lawrence D; Matheson, Christopher J; Wang, Ze-Jun; Levinson, Rock; Smothers, C Thetford; Woodward, John J; Honse, Yumiko; Lovinger, David; Rush, Anthony M; Sather, William A; Gustafson, Daniel L; Hoffman, Paula L

    2016-08-01

    Recent understanding of the systems that mediate complex disease states, has generated a search for molecules that simultaneously modulate more than one component of a pathologic pathway. Chronic pain syndromes are etiologically connected to functional changes (sensitization) in both peripheral sensory neurons and in the central nervous system (CNS). These functional changes involve modifications of a significant number of components of signal generating, signal transducing and signal propagating pathways. Our analysis of disease-related changes which take place in sensory neurons during sensitization led to the design of a molecule that would simultaneously inhibit peripheral NMDA receptors and voltage sensitive sodium channels. In the current report, we detail the selectivity of N,N-(diphenyl)-4-ureido-5,7-dichloro-2-carboxy-quinoline (DCUKA) for action at NMDA receptors composed of different subunit combinations and voltage sensitive sodium channels having different α subunits. We show that DCUKA is restricted to the periphery after oral administration, and that circulating blood levels are compatible with its necessary concentrations for effects at the peripheral cognate receptors/channels that were assayed in vitro. Our results demonstrate that DCUKA, at concentrations circulating in the blood after oral administration, can modulate systems which are upregulated during peripheral sensitization, and are important for generating and conducting pain information to the CNS. Furthermore, we demonstrate that DCUKA ameliorates the hyperalgesia of chronic pain without affecting normal pain responses in neuropathic and inflammation-induced chronic pain models. PMID:27158117

  12. Ethanol withdrawal hyper-responsiveness mediated by NMDA receptors in spinal cord motor neurons

    PubMed Central

    Li, Hui-Fang; Kendig, Joan J

    2003-01-01

    is necessary for withdrawal hyper-responsiveness. Both tyrosine kinase and PKC, but not PKA, appear to be essential for EtOH withdrawal hyper-responsiveness mediated by postsynaptic NMDA receptors in spinal cord motor neurons. PMID:12746225

  13. On the Role of Glutamate in Presynaptic Development: Possible Contributions of Presynaptic NMDA Receptors

    PubMed Central

    Fedder, Karlie N.; Sabo, Shasta L.

    2015-01-01

    Proper formation and maturation of synapses during development is a crucial step in building the functional neural circuits that underlie perception and behavior. It is well established that experience modifies circuit development. Therefore, understanding how synapse formation is controlled by synaptic activity is a key question in neuroscience. In this review, we focus on the regulation of excitatory presynaptic terminal development by glutamate, the predominant excitatory neurotransmitter in the brain. We discuss the evidence that NMDA receptor activation mediates these effects of glutamate and present the hypothesis that local activation of presynaptic NMDA receptors (preNMDARs) contributes to glutamate-dependent control of presynaptic development. Abnormal glutamate signaling and aberrant synapse development are both thought to contribute to the pathogenesis of a variety of neurodevelopmental disorders, including autism spectrum disorders, intellectual disability, epilepsy, anxiety, depression, and schizophrenia. Therefore, understanding how glutamate signaling and synapse development are linked is important for understanding the etiology of these diseases. PMID:26694480

  14. NMDA Receptor-Dependent Synaptic Reinforcement as a Crucial Process for Memory Consolidation

    NASA Astrophysics Data System (ADS)

    Shimizu, Eiji; Tang, Ya-Ping; Rampon, Claire; Tsien, Joe Z.

    2000-11-01

    The hippocampal CA1 region is crucial for converting new memories into long-term memories, a process believed to continue for week(s) after initial learning. By developing an inducible, reversible, and CA1-specific knockout technique, we could switch N-methyl-D-aspartate (NMDA) receptor function off or on in CA1 during the consolidation period. Our data indicate that memory consolidation depends on the reactivation of the NMDA receptor, possibly to reinforce site-specific synaptic modifications to consolidate memory traces. Such a synaptic reinforcement process may also serve as a cellular means by which the new memory is transferred from the hippocampus to the cortex for permanent storage.

  15. The effect of the NMDA receptor blocker, dextromethorphan, on cribbing in horses.

    PubMed

    Rendon, R A; Shuster, L; Dodman, N H

    2001-01-01

    Stereotypic cribbing in horses is thought to involve excess dopaminergic activity within the striatum. Various models of stress-induced stereotypies including cribbing in horses postulate that stress stimulates the release of endorphins, triggering the release of striatal dopamine. Dopamine in turn activates basal ganglia motor programs, reinforcing behavior via a reward mechanism. Furthermore, the release of dopamine by endorphins has been shown to depend on activation of NMDA receptors. In the present study, horses identified as cribbers and volunteered by their owners were treated with the NMDA receptor antagonist dextromethorphan (DM). When DM was administered via jugular injection (1 mg/kg), eight of nine horses responded with reductions in cribbing rate (CR) compared to baseline, and cribbing was suppressed completely for a period of time in almost half of the horses tested. PMID:11274707

  16. On the Role of Glutamate in Presynaptic Development: Possible Contributions of Presynaptic NMDA Receptors.

    PubMed

    Fedder, Karlie N; Sabo, Shasta L

    2015-01-01

    Proper formation and maturation of synapses during development is a crucial step in building the functional neural circuits that underlie perception and behavior. It is well established that experience modifies circuit development. Therefore, understanding how synapse formation is controlled by synaptic activity is a key question in neuroscience. In this review, we focus on the regulation of excitatory presynaptic terminal development by glutamate, the predominant excitatory neurotransmitter in the brain. We discuss the evidence that NMDA receptor activation mediates these effects of glutamate and present the hypothesis that local activation of presynaptic NMDA receptors (preNMDARs) contributes to glutamate-dependent control of presynaptic development. Abnormal glutamate signaling and aberrant synapse development are both thought to contribute to the pathogenesis of a variety of neurodevelopmental disorders, including autism spectrum disorders, intellectual disability, epilepsy, anxiety, depression, and schizophrenia. Therefore, understanding how glutamate signaling and synapse development are linked is important for understanding the etiology of these diseases. PMID:26694480

  17. Mobility of NMDA autoreceptors but not postsynaptic receptors at glutamate synapses in the rat entorhinal cortex

    PubMed Central

    Yang, Jian; Chamberlain, Sophie E L; Woodhall, Gavin L; Jones, Roland S G

    2008-01-01

    NMDA receptors (NMDAr) are known to undergo recycling and lateral diffusion in postsynaptic spines and dendrites. However, NMDAr are also present as autoreceptors on glutamate terminals, where they act to facilitate glutamate release, but it is not known whether these receptors are also mobile. We have used functional pharmacological approaches to examine whether NMDA receptors at excitatory synapses in the rat entorhinal cortex are mobile at either postsynaptic sites or in presynaptic terminals. When NMDAr-mediated evoked EPSCs (eEPSCs) were blocked by MK-801, they showed no evidence of recovery when the irreversible blocker was removed, suggesting that postsynaptic NMDAr were relatively stably anchored at these synapses. However, using frequency-dependent facilitation of AMPA receptor (AMPAr)-mediated eEPSCs as a reporter of presynaptic NMDAr activity, we found that when facilitation was blocked with MK-801 there was a rapid (∼30–40 min) anomalous recovery upon removal of the antagonist. This was not observed when global NMDAr blockade was induced by combined perfusion with MK-801 and NMDA. Anomalous recovery was accompanied by an increase in frequency of spontaneous EPSCs, and a variable increase in frequency-facilitation. Following recovery from blockade of presynaptic NMDAr with a competitive antagonist, frequency-dependent facilitation of AMPAr-mediated eEPSCs was also transiently enhanced. Finally, an increase in frequency of miniature EPSCs induced by NMDA was succeeded by a persistent decrease. Our data provide the first evidence for mobility of NMDAr in the presynaptic terminals, and may point to a role of this process in activity-dependent control of glutamate release. PMID:18718983

  18. Benzimidazole-2-carboxamides as novel NR2B selective NMDA receptor antagonists.

    PubMed

    Borza, István; Kolok, Sándor; Gere, Anikó; Nagy, József; Fodor, László; Galgóczy, Kornél; Fetter, József; Bertha, Ferenc; Agai, Béla; Horváth, Csilla; Farkas, Sándor; Domány, György

    2006-09-01

    A novel series of benzimidazole-2-carboxamide derivatives was prepared and identified as NR2B selective NMDA receptor antagonists. The influence of some structural elements, like H-bond donor groups placed on the benzimidazole skeleton and the substitution pattern of the piperidine ring, on the biological activity was studied. Compound 6a showed excellent analgetic activity in the mouse formalin test following po administration. PMID:16782335

  19. NMDA Receptor-Mediated Activation of NADPH Oxidase and Glomerulosclerosis in Hyperhomocysteinemic Rats

    PubMed Central

    Zhang, Chun; Yi, Fan; Xia, Min; Boini, Krishna M.; Zhu, Qing; Laperle, Laura A.; Abais, Justine M.; Brimson, Christopher A.

    2010-01-01

    Abstract This study investigated the role of NMDA receptor in hyperhomocyteinemia (hHcys)-induced NADPH oxidase (Nox) activation and glomerulosclerosis. Sprague–Dawley rats were fed a folate-free (FF) diet to produce hHcys, and a NMDA receptor antagonist, MK-801, was administrated. Rats fed the FF diet exhibited significantly increased plasma homocysteine levels, upregulated NMDA receptor expression, enhanced Nox activity and Nox-dependent O2.− production in the glomeruli, which were accompanied by remarkable glomerulosclerosis. MK-801 treatment significantly inhibited Nox-dependent O2.− production induced by hHcys and reduced glomerular damage index as compared with vehicle-treated hHcys rats. Correspondingly, glomerular deposition of extracellular matrix components in hHcys rats was ameliorated by the administration of MK-801. Additionally, hHcys induced an increase in tissue inhibitor of metalloproteinase-1 (TIMP-1) expression and a decrease in matrix metalloproteinase (MMP)-1 and MMP-9 activities, all of which were abolished by MK-801 treatment. In vitro studies showed that homocysteine increased Nox-dependent O2.− generation in rat mesangial cells, which was blocked by MK-801. Pretreatment with MK-801 also reversed homocysteine-induced decrease in MMP-1 activity and increase in TIMP-1 expression. These results support the view that the NMDA receptor may mediate Nox activation in the kidney during hHcys and thereby play a critical role in the development of hHcys-induced glomerulosclerosis. Antioxid. Redox Signal. 13, 975–986. PMID:20406136

  20. The Impact of NMDA Receptor Blockade on Human Working Memory-Related Prefrontal Function and Connectivity

    PubMed Central

    Driesen, Naomi R; McCarthy, Gregory; Bhagwagar, Zubin; Bloch, Michael H; Calhoun, Vincent D; D'Souza, Deepak C; Gueorguieva, Ralitza; He, George; Leung, Hoi-Chung; Ramani, Ramachandran; Anticevic, Alan; Suckow, Raymond F; Morgan, Peter T; Krystal, John H

    2013-01-01

    Preclinical research suggests that N-methyl-D-aspartate glutamate receptors (NMDA-Rs) have a crucial role in working memory (WM). In this study, we investigated the role of NMDA-Rs in the brain activation and connectivity that subserve WM. Because of its importance in WM, the lateral prefrontal cortex, particularly the dorsolateral prefrontal cortex and its connections, were the focus of analyses. Healthy participants (n=22) participated in a single functional magnetic resonance imaging session. They received saline and then the NMDA-R antagonist ketamine while performing a spatial WM task. Time-course analysis was used to compare lateral prefrontal activation during saline and ketamine administration. Seed-based functional connectivity analysis was used to compare dorsolateral prefrontal connectivity during the two conditions and global-based connectivity was used to test for laterality in these effects. Ketamine reduced accuracy on the spatial WM task and brain activation during the encoding and early maintenance (EEM) period of task trials. Decrements in task-related activation during EEM were related to performance deficits. Ketamine reduced connectivity in the DPFC network bilaterally, and region-specific reductions in connectivity were related to performance. These results support the hypothesis that NMDA-Rs are critical for WM. The knowledge gained may be helpful in understanding disorders that might involve glutamatergic deficits such as schizophrenia and developing better treatments. PMID:23856634

  1. Characterising seizures in anti-NMDA-receptor encephalitis with dynamic causal modelling

    PubMed Central

    Cooray, Gerald K.; Sengupta, Biswa; Douglas, Pamela; Englund, Marita; Wickstrom, Ronny; Friston, Karl

    2015-01-01

    We characterised the pathophysiology of seizure onset in terms of slow fluctuations in synaptic efficacy using EEG in patients with anti-N-methyl-d-aspartate receptor (NMDA-R) encephalitis. EEG recordings were obtained from two female patients with anti-NMDA-R encephalitis with recurrent partial seizures (ages 19 and 31). Focal electrographic seizure activity was localised using an empirical Bayes beamformer. The spectral density of reconstructed source activity was then characterised with dynamic causal modelling (DCM). Eight models were compared for each patient, to evaluate the relative contribution of changes in intrinsic (excitatory and inhibitory) connectivity and endogenous afferent input. Bayesian model comparison established a role for changes in both excitatory and inhibitory connectivity during seizure activity (in addition to changes in the exogenous input). Seizures in both patients were associated with a sequence of changes in inhibitory and excitatory connectivity; a transient increase in inhibitory connectivity followed by a transient increase in excitatory connectivity and a final peak of excitatory–inhibitory balance at seizure offset. These systematic fluctuations in excitatory and inhibitory gain may be characteristic of (anti NMDA-R encephalitis) seizures. We present these results as a case study and replication to motivate analyses of larger patient cohorts, to see whether our findings generalise and further characterise the mechanisms of seizure activity in anti-NMDA-R encephalitis. PMID:26032883

  2. A randomized placebo-controlled trial of an NMDA receptor antagonist in sleep-disordered breathing.

    PubMed

    Torvaldsson, Stefan; Grote, Ludger; Peker, Yüksel; Basun, Hans; Hedner, Jan

    2005-06-01

    Hypoxemia is a powerful stimulus of glutamate release in the central nervous system (CNS) and a hallmark phenomenon in sleep disordered breathing (SDB). Glutamate effects that include neuronal damage and apoptosis following hypoxemia and apnea following microinjections in animal models are in part mediated via postjunctional N-methyl-D-aspartate (NMDA) receptors. This was a double blind, randomized, placebo-controlled single dose cross-over study of the NMDA receptor antagonist AR-R15896AR in 15 male patients with moderate to severe SDB. Seven patients received 120 mg and eight patients received 350 mg AR-R15896AR or corresponding placebo (given by 2 h infusion) starting half an hour before estimated sleep onset. AR-R15896AR concentrations were in line with the predicting kinetic model. A standard polysomnographic montage was applied. Repeated plasma samples were obtained in nine patients for analysis of plasma glutamate. Glutamate concentration in plasma did not change overnight and was unrelated to severity of SDB. Overall AHI (apnea-hypopnea index; primary efficacy variable) or investigated oxygen saturation variables were not significantly changed after AR-R15896AR at either dosage level. Side effects were mostly confined to the higher dose level and included vivid dreams, nightmares as well as in two cases mild hallucinations. The previously postulated role of glutamate in SDB could not be confirmed after AR-R15896AR induced NMDA-receptor blockade. PMID:15910512

  3. Opposite effects of GABAA and NMDA receptor antagonists on ethanol-induced behavioral sleep in rats.

    PubMed

    Beleslin, D B; Djokanović, N; Jovanović Mićić, D; Samardzić, R

    1997-01-01

    The effects of the GABAA receptor antagonists, pentylenetetrazol, bicuculline, and picrotoxin, the glycine antagonist, strychnine, and the NMDA receptor antagonist, memantine, on ethanol-induced behavioral sleep and body temperature were investigated. Pentylenetetrazol, bicuculline, and picrotoxin given prior and following ethanol reduced the behavioral sleep and potentiated the hypothermia caused by ethanol. However, convulsions appeared when bicuculline, but not pentylenetetrazol and picrotoxin, were given following ethanol. After the reversal of unconsciousness in rats without convulsions the animals remained awake throughout the experiments without motor incoordination, hyperexcitability, and sedation, but they were in hypothermia within 12 h. The glycine antagonist, strychnine, given prior or after ethanol had virtually no effect on ethanol-induced behavioral sleep and hypothermia. Ethanol given prior or following strychnine failed to antagonize strychnine-induced convulsions. The NMDA receptor antagonist, memantine, given following ethanol potentiated the behavioral sleep and had virtually no effect on hypothermia induced by ethanol. It is suggested that the ethanol-induced behavioral sleep may be attributed to its ability to enhance the GABAergic mechanisms and to inhibit NMDA-mediated excitatory responses. However, the ethanol-induced hypothermia may be ascribed solely to the facilitation of GABAergic transmission. Further, it is postulated that a bidirectional inhibitory system subserves the regulation of behavioral sleep and convulsions. However, one-way inhibitory system underlies the ethanol-induced hypothermia. PMID:9085718

  4. A role for the cytoplasmic polyadenylation element in NMDA receptor-regulated mRNA translation in neurons.

    PubMed

    Wells, D G; Dong, X; Quinlan, E M; Huang, Y S; Bear, M F; Richter, J D; Fallon, J R

    2001-12-15

    The ability of neurons to modify synaptic connections based on activity is essential for information processing and storage in the brain. The induction of long-lasting changes in synaptic strength requires new protein synthesis and is often mediated by NMDA-type glutamate receptors (NMDARs). We used a dark-rearing paradigm to examine mRNA translational regulation in the visual cortex after visual experience-induced synaptic plasticity. In this model system, we demonstrate that visual experience induces the translation of mRNA encoding the alpha-subunit of calcium/calmodulin-dependent kinase II in the visual cortex. Furthermore, this increase in translation is NMDAR dependent. One potential source for newly synthesized proteins is the translational activation of dormant cytoplasmic mRNAs. To examine this possibility, we developed a culture-based assay system to study translational regulation in neurons. Cultured hippocampal neurons were transfected with constructs encoding green fluorescent protein (GFP). At 6 hr after transfection, approximately 35% of the transfected neurons (as determined by in situ hybridization) expressed detectable GFP protein. Glutamate stimulation of the cultures at this time induced an increase in the number of neurons expressing GFP protein that was NMDAR dependent. Importantly, the glutamate-induced increase was only detected when the 3'-untranslated region of the GFP constructs contained intact cytoplasmic polyadenylation elements (CPEs). Together, these findings define a molecular mechanism for activity-dependent synaptic plasticity that is mediated by the NMDA receptor and requires the CPE-dependent translation of an identified mRNA. PMID:11739565

  5. The hippocampal NMDA receptors may be involved in acquisition, but not expression of ACPA-induced place preference.

    PubMed

    Nasehi, Mohammad; Sharaf-Dolgari, Elmira; Ebrahimi-Ghiri, Mohaddeseh; Zarrindast, Mohammad-Reza

    2015-12-01

    Numerous studies have investigated the functional interactions between the endocannabinoid and glutamate systems in the hippocampus. The present study was made to test whether N-methyl-D-aspartate (NMDA) receptors of the CA1 region of the dorsal hippocampus (CA1) are implicated in ACPA (a selective cannabinoid CB1 receptor agonist)-induced place preference. Using a 3-day schedule of conditioning, it was found that intraperitoneal (i.p.) administration of ACPA (0.02mg/kg) caused a significant conditioned place preference (CPP) in male albino NMRI mice. Intra-CA1 microinjection of the NMDA or D-[1]-2-amino-7-Phosphonoheptanoic acid (D-AP7, NMDA receptor antagonist), failed to induce CPP or CPA (condition place aversion), while NMDA (0.5μg/mouse) potentiated the ACPA (0.01mg/kg)-induced CPP; and D-AP7 (a specific NMDA receptor antagonist; 0.5 and 1μg/mouse) reversed the ACPA (0.02mg/kg)-induced CPP. Moreover, microinjection of different doses of glutamatergic agents on the testing day did not alter the expression of ACPA-induced place preference. None of the treatments, with the exception of ACPA (0.04mg/kg), had an effect on locomotor activity. In conclusion, these observations provide evidence that glutamate NMDA receptors of the CA1 may be involved in the potentiation of ACPA rewarding properties in the acquisition, but not expression, of CPP in mice. PMID:26072736

  6. The Rac1-GEF Tiam1 couples the NMDA receptor to the activity-dependent development of dendritic arbors and spines.

    PubMed

    Tolias, Kimberley F; Bikoff, Jay B; Burette, Alain; Paradis, Suzanne; Harrar, Dana; Tavazoie, Sohail; Weinberg, Richard J; Greenberg, Michael E

    2005-02-17

    NMDA-type glutamate receptors play a critical role in the activity-dependent development and structural remodeling of dendritic arbors and spines. However, the molecular mechanisms that link NMDA receptor activation to changes in dendritic morphology remain unclear. We report that the Rac1-GEF Tiam1 is present in dendrites and spines and is required for their development. Tiam1 interacts with the NMDA receptor and is phosphorylated in a calcium-dependent manner in response to NMDA receptor stimulation. Blockade of Tiam1 function with RNAi and dominant interfering mutants of Tiam1 suggests that Tiam1 mediates effects of the NMDA receptor on dendritic development by inducing Rac1-dependent actin remodeling and protein synthesis. Taken together, these findings define a molecular mechanism by which NMDA receptor signaling controls the growth and morphology of dendritic arbors and spines. PMID:15721239

  7. The AMPA receptor subunit GluR1 regulates dendritic architecture of motor neurons

    NASA Technical Reports Server (NTRS)

    Inglis, Fiona M.; Crockett, Richard; Korada, Sailaja; Abraham, Wickliffe C.; Hollmann, Michael; Kalb, Robert G.

    2002-01-01

    The morphology of the mature motor neuron dendritic arbor is determined by activity-dependent processes occurring during a critical period in early postnatal life. The abundance of the AMPA receptor subunit GluR1 in motor neurons is very high during this period and subsequently falls to a negligible level. To test the role of GluR1 in dendrite morphogenesis, we reintroduced GluR1 into rat motor neurons at the end of the critical period and quantitatively studied the effects on dendrite architecture. Two versions of GluR1 were studied that differed by the amino acid in the "Q/R" editing site. The amino acid occupying this site determines single-channel conductance, ionic permeability, and other essential electrophysiologic properties of the resulting receptor channels. We found large-scale remodeling of dendritic architectures in a manner depending on the amino acid occupying the Q/R editing site. Alterations in the distribution of dendritic arbor were not prevented by blocking NMDA receptors. These observations suggest that the expression of GluR1 in motor neurons modulates a component of the molecular substrate of activity-dependent dendrite morphogenesis. The control of these events relies on subunit-specific properties of AMPA receptors.

  8. NMDA receptors are involved in the antidepressant-like effects of capsaicin following amphetamine withdrawal in male mice.

    PubMed

    Amiri, Shayan; Alijanpour, Sakineh; Tirgar, Fatemeh; Haj-Mirzaian, Arya; Amini-Khoei, Hossein; Rahimi-Balaei, Maryam; Rastegar, Mojgan; Ghaderi, Marzieh; Ghazi-Khansari, Mahmoud; Zarrindast, Mohammad-Reza

    2016-08-01

    Amphetamine withdrawal (AW) is accompanied by diminished pleasure and depression which plays a key role in drug relapse and addictive behaviors. There is no efficient treatment for AW-induced depression and underpinning mechanisms were not well determined. Considering both transient receptor potential cation channel, subfamily V, member 1 (TRPV1) and N-Methyl-d-aspartate (NMDA) receptors contribute to pathophysiology of mood and addictive disorders, in this study, we investigated the role of TRPV1 and NMDA receptors in mediating depressive-like behaviors following AW in male mice. Results revealed that administration of capsaicin, TRPV1 agonist, (100μg/mouse, i.c.v.) and MK-801, NMDA receptor antagonist (0.005mg/kg, i.p.) reversed AW-induced depressive-like behaviors in forced swimming test (FST) and splash test with no effect on animals' locomotion. Co-administration of sub-effective doses of MK-801 (0.001mg/kg, i.p.) and capsaicin (10μg/mouse, i.c.v) exerted antidepressant-like effects in behavioral tests. Capsazepine, TRPV1 antagonist, (100μg/mouse, i.c.v) and NMDA, NMDA receptor agonist (7.5mg/kg, i.p.) abolished the effects of capsaicin and MK-801, respectively. None of aforementioned treatments had any effect on behavior of control animals. Collectively, our findings showed that activation of TRPV1 and blockade of NMDA receptors produced antidepressant-like effects in male mice following AW, and these receptors are involved in AW-induced depressive-like behaviors. Further, we found that rapid antidepressant-like effects of capsaicin in FST and splash test are partly mediated by NMDA receptors. PMID:27167081

  9. NMDA Receptor Agonism and Antagonism within the Amygdaloid Central Nucleus Suppresses Pain Affect: Differential Contribution of the Ventrolateral Periaqueductal Gray

    PubMed Central

    Spuz, Catherine A.; Tomaszycki, Michelle L.; Borszcz, George S.

    2015-01-01

    The amygdala contributes to the generation of pain affect and the amygdaloid central nucleus (CeA) receives nociceptive input that is mediated by glutamatergic neurotransmission. The present study compared the contribution of N-methyl-D-aspartate (NMDA) receptor agonism and antagonism in CeA to generation of the affective response of rats to an acute noxious stimulus. Vocalizations that occur following a brief tail shock (vocalization afterdischarges) are a validated rodent model of pain affect, and were preferentially suppressed, in a dose dependent manner, by bilateral injection into CeA of NMDA (.1 µg, .25 µg, .5 µg, or 1 µg/side), or the NMDA receptor antagonist D-2-amino-5-phosphonovalerate (AP5, 1 µg, 2 µg, or 4 µg/side). Vocalizations that occur during tail shock were suppressed to a lesser degree, whereas, spinal motor reflexes (tail flick and hind limb movements) were unaffected by injection of NMDA or AP5 into CeA. Injection of NMDA, but not AP5, into CeA increased c-Fos immunoreactivity in the ventrolateral periaqueductal gray (vlPAG), and unilateral injection of the µ-opiate receptor antagonist H-D-Phe-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH2 (CTAP, 0.25 µg) into vlPAG prevented the antinociception generated by injection of NMDA into CeA. These findings demonstrate that although NMDA receptor agonism and antagonism in CeA produce similar suppression of pain behaviors they do so via different neurobiological mechanisms. Perspective The amygdala contributes to production of the emotional dimension of pain. NMDA receptor agonism and antagonism within the central nucleus of the amygdala suppressed rats’ emotional response to acute painful stimulation. Understanding the neurobiology underlying emotional responses to pain will provide insights into new treatments for pain and its associated affective disorders. PMID:25261341

  10. Cholinergic, but not NMDA, receptors in the lateral entorhinal cortex mediate acquisition in trace eyeblink conditioning.

    PubMed

    Tanninen, Stephanie E; Yu, XiaoTian; Giritharan, Thamy; Tran, Lina; Bakir, Rami; Volle, Julien; Morrissey, Mark D; Takehara-Nishiuchi, Kaori

    2015-11-01

    Anatomical and electrophysiological studies collectively suggest that the entorhinal cortex consists of several subregions, each of which is involved in the processing of different types of information. Consistent with this idea, we previously reported that the dorsolateral portion of the entorhinal cortex (DLE), but not the caudomedial portion, is necessary for the expression of a memory association between temporally discontiguous stimuli in trace eyeblink conditioning (Morrissey et al. (2012) J Neurosci 32:5356-5361). The present study examined whether memory acquisition depends on the DLE and what types of local neurotransmitter mechanisms are involved in memory acquisition and expression. Male Long-Evans rats experienced trace eyeblink conditioning, in which an auditory conditioned stimulus (CS) was paired with a mildly aversive electric shock to the eyelid (US) with a stimulus-free interval of 500 ms. Immediately before the conditioning, the rats received a microinfusion of neuroreactive substances into the DLE. We found that reversible inactivation of the DLE with GABAA receptor agonist, muscimol impaired memory acquisition. Furthermore, blockade of local muscarinic acetylcholine receptors (mACh) with scopolamine retarded memory acquisition while blockade of local NMDA receptors with APV had no effect. Memory expression was not impaired by either type of receptor blocker. These results suggest that the DLE is necessary for memory acquisition, and that acquisition depends on the integrity of local mACh receptor-dependent firing modulation, but not NMDA receptor-dependent synaptic plasticity. PMID:25865030

  11. Gestational nicotine exposure regulates expression of AMPA and NMDA receptors and their signaling apparatus in developing and adult rat hippocampus

    PubMed Central

    Wang, Hong; Dávila-García, Martha I.; Yarl, Weonpo; Gondré-Lewis, Marjorie C.

    2011-01-01

    Untimely activation of nicotinic acetylcholine receptor (nAChR) by nicotine results in short- and long-term consequences on learning and behavior. In this study, the aim was to determine how prenatal nicotine exposure affects components of glutamatergic signaling in the hippocampus during postnatal development. We investigated regulation of both nAChRs and glutamate receptors for α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) and N-methyl-D-aspartate (NMDA), from postnatal day (P) 1 to P63 after a temporally restricted exposure to saline or nicotine for 14 days in utero. We analyzed postsynaptic density components associated with AMPAR and NMDAR signaling: Calcium/calmodulin-dependent protein kinase II α (CaMKIIα), Calmodulin (CaM), and postsynaptic density-95 (PSD95), as well as presynaptically localized synaptosomal-associated protein 25 (SNAP25). At P1, there was significantly heightened expression of AMPAR subunit GluR1 but not GluR2, and of NMDAR subunits NR1, NR2a and NR2d but not NR2b. NR2c was not detectable. At P1, the postsynaptic proteins CaMKIIα, CaM, and PSD95 were also significantly upregulated, together with presynaptic SNAP25. This enhanced expression of glutamate receptors and signaling proteins was concomitant with elevated levels of [3H] Epibatidine (EB) binding in prenatal nicotine-exposed hippocampus, indicating that α4β2 nAChR may influence glutamatergic function in the hippocampus at P1. By P14, neither [3H]EB binding nor the expression levels of subunits GluR1, GluR2, NR1, NR2a, NR2b, NR2c, or NR2d seemed changed with prenatal nicotine. However, CaMKIIα was significantly upregulated with nicotine treatment while CaM showed downregulation at P14. The effects of nicotine persisted in young adult brains at P63. They exhibited significantly downregulated GluR2, NR1, and NR2c expression levels in hippocampal homogenates and a considerably muted overall distribution of [3H]AMPA binding in areas CA1, CA2, CA3, and the dentate

  12. A negative feedback loop controls NMDA receptor function in cortical interneurons via neuregulin 2/ErbB4 signalling

    PubMed Central

    Vullhorst, Detlef; Mitchell, Robert M.; Keating, Carolyn; Roychowdhury, Swagata; Karavanova, Irina; Tao-Cheng, Jung-Hwa; Buonanno, Andres

    2015-01-01

    The neuregulin receptor ErbB4 is an important modulator of GABAergic interneurons and neural network synchronization. However, little is known about the endogenous ligands that engage ErbB4, the neural processes that activate them or their direct downstream targets. Here we demonstrate, in cultured neurons and in acute slices, that the NMDA receptor is both effector and target of neuregulin 2 (NRG2)/ErbB4 signalling in cortical interneurons. Interneurons co-express ErbB4 and NRG2, and pro-NRG2 accumulates on cell bodies atop subsurface cisternae. NMDA receptor activation rapidly triggers shedding of the signalling-competent NRG2 extracellular domain. In turn, NRG2 promotes ErbB4 association with GluN2B-containing NMDA receptors, followed by rapid internalization of surface receptors and potent downregulation of NMDA but not AMPA receptor currents. These effects occur selectively in ErbB4-positive interneurons and not in ErbB4-negative pyramidal neurons. Our findings reveal an intimate reciprocal relationship between ErbB4 and NMDA receptors with possible implications for the modulation of cortical microcircuits associated with cognitive deficits in psychiatric disorders. PMID:26027736

  13. Effects of blockade of NMDA receptors on cerebral oxygen consumption during hyperosmolar BBB disruption in rats.

    PubMed

    Chi, Oak Z; Barsoum, Sylviana; Grayson, Jeremy; Hunter, Christine; Liu, Xia; Weiss, Harvey R

    2013-03-15

    Hyperosmolar blood-brain barrier (BBB) disruption has been reported to increase cerebral O2 consumption. This study was performed to test whether blockade of N-methyl-d-aspartate (NMDA) receptor would affect cerebral O2 consumption during hyperosmolar BBB disruption. A competitive NMDA receptor antagonist CGS-19755 10mg/kg was injected iv 15min before intracarotid infusion of 25% mannitol. Twelve min after BBB disruption, the BBB transfer coefficient (Ki) of (14)C-α-aminoisobutyric acid ((14)C-AIB) was measured. Regional cerebral blood flow (rCBF), regional arteriolar and venular O2 saturation (SaO2 and SvO2 respectively), and O2 consumption were determined using (14)C-iodoantipyrine autoradiography and cryomicrospectrophotometry in alternate slices of the brain tissue. The Ki of (14)C-AIB was markedly increased with hyperosmolar mannitol in both the control (5.8×) and the CGS treated rats (5.2×). With BBB disruption, the O2 consumption was significantly increased (+39%) only in the control but not in the CGS treated rats and was significantly lower (-29%) in the CGS treated than the control rats. The distribution of SvO2 was significantly shifted to the higher concentrations with CGS treatment. Our data demonstrated an increase of O2 consumption by hyperosmolar BBB disruption and attenuation of the increase with NMDA blockade without affecting the degree of BBB disruption. PMID:23357315

  14. NMDA Receptor Antagonist Ketamine Distorts Object Recognition by Reducing Feedback to Early Visual Cortex.

    PubMed

    van Loon, Anouk M; Fahrenfort, Johannes J; van der Velde, Bauke; Lirk, Philipp B; Vulink, Nienke C C; Hollmann, Markus W; Scholte, H Steven; Lamme, Victor A F

    2016-05-01

    It is a well-established fact that top-down processes influence neural representations in lower-level visual areas. Electrophysiological recordings in monkeys as well as theoretical models suggest that these top-down processes depend on NMDA receptor functioning. However, this underlying neural mechanism has not been tested in humans. We used fMRI multivoxel pattern analysis to compare the neural representations of ambiguous Mooney images before and after they were recognized with their unambiguous grayscale version. Additionally, we administered ketamine, an NMDA receptor antagonist, to interfere with this process. Our results demonstrate that after recognition, the pattern of brain activation elicited by a Mooney image is more similar to that of its easily recognizable grayscale version than to the pattern evoked by the identical Mooney image before recognition. Moreover, recognition of Mooney images decreased mean response; however, neural representations of separate images became more dissimilar. So from the neural perspective, unrecognizable Mooney images all "look the same", whereas recognized Mooneys look different. We observed these effects in posterior fusiform part of lateral occipital cortex and in early visual cortex. Ketamine distorted these effects of recognition, but in early visual cortex only. This suggests that top-down processes from higher- to lower-level visual areas might operate via an NMDA pathway. PMID:25662715

  15. Glossopharyngeal long-term facilitation requires serotonin 5-HT2 and NMDA receptors in rats

    PubMed Central

    Cao, Ying; Liu, Chun; Ling, Liming

    2009-01-01

    Although the glossopharyngeal nerve (IX) is mainly a sensory nerve, it innervates stylopharyngeus and some other pharyngeal muscles, whose excitations would likely improve upper airway patency since electrical IX stimulation increases pharyngeal airway size. As acute intermittent hypoxia (AIH) induces hypoglossal and genioglossal long-term facilitation (LTF), we hypothesized that AIH induces glossopharyngeal LTF, which requires serotonin 5-HT2 and NMDA receptors. Integrated IX activity was recorded in anesthetized, vagotomized, paralyzed and ventilated rats before, during and after 5 episodes of 3-min isocapnic 12% O2 with 3-min intervals of 50% O2. Either saline, ketanserin (5-HT2 antagonist, 2 mg/kg) or MK-801 (NMDA antagonist, 0.2 mg/kg) was (i.v.) injected 30–60 min before AIH. Both phasic and tonic IX activities were persistently increased (both P<0.05) after AIH in vehicle, but not ketanserin or MK-801, rats. Hypoxic glossopharyngeal responses were minimally changed after either drug. These data suggest that AIH induces both phasic and tonic glossopharyngeal LTF, which requires activation of 5-HT2 and NMDA receptors. PMID:20026287

  16. Silent NMDA receptor-mediated synapses are developmentally regulated in the dorsal horn of the rat spinal cord.

    PubMed

    Baba, H; Doubell, T P; Moore, K A; Woolf, C J

    2000-02-01

    In vitro whole cell patch-clamp recording techniques were utilized to study silent pure-N-methyl-D-aspartate (NMDA) receptor-mediated synaptic responses in lamina II (substantia gelatinosa, SG) and lamina III of the spinal dorsal horn. To clarify whether these synapses are present in the adult and contribute to neuropathic pain, transverse lumbar spinal cord slices were prepared from neonatal, naive adult and adult sciatic nerve transected rats. In neonatal rats, pure-NMDA receptor-mediated excitatory postsynaptic currents (EPSCs) were elicited in SG neurons either by focal intraspinal stimulation (n = 15 of 20 neurons) or focal stimulation of the dorsal root (n = 2 of 7 neurons). In contrast, in slices from naive adult rats, no silent pure-NMDA EPSCs were recorded in SG neurons following focal intraspinal stimulation (n = 27), and only one pure-NMDA EPSC was observed in lamina III (n = 23). Furthermore, in rats with chronic sciatic nerve transection, pure-NMDA EPSCs were elicited by focal intraspinal stimulation in only 2 of 45 SG neurons. Although a large increase in Abeta fiber evoked mixed alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and NMDA receptor-mediated synapses was detected after sciatic nerve injury, Abeta fiber-mediated pure-NMDA EPSCs were not evoked in SG neurons by dorsal root stimulation. Pure-NMDA receptor-mediated EPSCs are therefore a transient, developmentally regulated phenomenon, and, although they may have a role in synaptic refinement in the immature dorsal horn, they are unlikely to be involved in receptive field plasticity in the adult. PMID:10669507

  17. Prenatal NMDA Receptor Antagonism Impaired Proliferation of Neuronal Progenitor, Leading to Fewer Glutamatergic Neurons in the Prefrontal Cortex

    PubMed Central

    Toriumi, Kazuya; Mouri, Akihiro; Narusawa, Shiho; Aoyama, Yuki; Ikawa, Natsumi; Lu, Lingling; Nagai, Taku; Mamiya, Takayoshi; Kim, Hyoung-Chun; Nabeshima, Toshitaka

    2012-01-01

    N-methyl--aspartate (NMDA) receptor is a glutamate receptor which has an important role on mammalian brain development. We have reported that prenatal treatment with phencyclidine (PCP), a NMDA receptor antagonist, induces long-lasting behavioral deficits and neurochemical changes. However, the mechanism by which the prenatal antagonism of NMDA receptor affects neurodevelopment, resulting in behavioral deficits, has remained unclear. Here, we report that prenatal NMDA receptor antagonism impaired the proliferation of neuronal progenitors, leading to a decrease in the progenitor pool in the ventricular and the subventricular zone. Furthermore, using a PCR array focused on neurogenesis and neuronal stem cells, we evaluated changes in gene expression causing the impairment of neuronal progenitor proliferation and found aberrant gene expression, such as Notch2 and Ntn1, in prenatal PCP-treated mice. Consequently, the density of glutamatergic neurons in the prefrontal cortex was decreased, probably resulting in glutamatergic hypofunction. Prenatal PCP-treated mice displayed behavioral deficits in cognitive memory and sensorimotor gating until adulthood. These findings suggest that NMDA receptors regulate the proliferation and maturation of progenitor cells for glutamatergic neuron during neurodevelopment, probably via the regulation of gene expression. PMID:22257896

  18. Physiological Roles of Non-Neuronal NMDA Receptors.

    PubMed

    Hogan-Cann, Adam D; Anderson, Christopher M

    2016-09-01

    Glutamate serves as the dominant central nervous system (CNS) excitatory neurotransmitter, in part by activating N-methyl-D-aspartate receptors (NMDARs). While the structure, function, and distribution of neuronal NMDARs have been extensively elucidated, NMDARs are also expressed across a wide spectrum of non-neuronal cells, including central and peripheral glial cells, endothelium, kidney, bone, pancreas, and others. These receptors are poorly understood compared to neuronal receptors, but there is a developing consensus that they have distinct structural and functional properties when activated by glutamate, NMDAR co-agonists, and in some cases by metabolites of tryptophan and methionine. It is also clear that non-neuronal NMDARs may participate in an array of physiological and pathophysiological processes, including but not limited to bone deposition, wound healing, insulin secretion, blood-brain barrier integrity, and myelination. These developing lines of evidence are stimulating exploration of non-neuronal NMDARs as a therapeutic target in several disorders. PMID:27338838

  19. Region-selective effects of neuroinflammation and antioxidant treatment on peripheral benzodiazepine receptors and NMDA receptors in the rat brain

    SciTech Connect

    Biegon, A.; Alvarado, M.; Budinger, T.F.; Grossman, R.; Hensley, K.; West, M.S.; Kotake, Y.; Ono, M.; Floyd, R.A.

    2001-12-10

    Following induction of acute neuroinflammation by intracisternal injection of endotoxin (lipopolysaccharide) in rats, quantitative autoradiography was used to assess the regional level of microglial activation and glutamate (NMDA) receptor binding. The possible protective action of the antioxidant phenyl-tert-butyl nitrone in this model was tested by administering the drug in the drinking water for 6 days starting 24 hours after endotoxin injection. Animals were killed 7 days post-injection and consecutive cryostat brain sections labeled with [3H]PK11195 as a marker of activated microglia and [125I]iodoMK801 as a marker of the open-channel, activated state of NMDA receptors. Lipopolysaccharide increased [3H]PK11195 binding in the brain, with the largest increases (2-3 fold) in temporal and entorhinal cortex, hippocampus, and substantia innominata. A significant (>50 percent) decrease in [125I]iodoMK801 binding was found in the same brain regions. Phenyl-tert-butyl nitrone treatment resulted in a partial inhibition ({approx}25 percent decrease) of the lipopolysaccharide-induced increase in [3H]PK11195 binding but completely reversed the lipopolysaccharide-induced decrease in [125I]iodoMK80 binding in the entorhinal cortex, hippocampus, and substantia innominata. Loss of NMDA receptor function in cortical and hippocampal regions may contribute to the cognitive deficits observed in diseases with a neuroinflammatory component, such as meningitis or Alzheimer's disease.

  20. Functional NMDA receptors are expressed by both AII and A17 amacrine cells in the rod pathway of the mammalian retina.

    PubMed

    Zhou, Yifan; Tencerová, Barbora; Hartveit, Espen; Veruki, Margaret L

    2016-01-01

    At many glutamatergic synapses, non-N-methyl-d-aspartate (NMDA) and NMDA receptors are coexpressed postsynaptically. In the mammalian retina, glutamatergic rod bipolar cells are presynaptic to two rod amacrine cells (AII and A17) that constitute dyad postsynaptic partners opposite each presynaptic active zone. Whereas there is strong evidence for expression of non-NMDA receptors by both AII and A17 amacrines, the expression of NMDA receptors by the pre- and postsynaptic neurons in this microcircuit has not been resolved. In this study, using patch-clamp recording from visually identified cells in rat retinal slices, we investigated the expression and functional properties of NMDA receptors in these cells with a combination of pharmacological and biophysical methods. Pressure application of NMDA did not evoke a response in rod bipolar cells, but for both AII and A17 amacrines, NMDA evoked responses that were blocked by a competitive antagonist (CPP) applied extracellularly and an open channel blocker (MK-801) applied intracellularly. NMDA-evoked responses also displayed strong Mg(2+)-dependent voltage block and were independent of gap junction coupling. With low-frequency application (60-s intervals), NMDA-evoked responses remained stable for up to 50 min, but with higher-frequency stimulation (10- to 20-s intervals), NMDA responses were strongly and reversibly suppressed. We observed strong potentiation when NMDA was applied in nominally Ca(2+)-free extracellular solution, potentially reflecting Ca(2+)-dependent NMDA receptor inactivation. These results indicate that expression of functional (i.e., conductance-increasing) NMDA receptors is common to both AII and A17 amacrine cells and suggest that these receptors could play an important role for synaptic signaling, integration, or plasticity in the rod pathway. PMID:26561610

  1. Effects of single prolonged stress and D-cycloserine on contextual fear extinction and hippocampal NMDA receptor expression in a rat model of PTSD.

    PubMed

    Yamamoto, Shigeto; Morinobu, Shigeru; Fuchikami, Manabu; Kurata, Akiko; Kozuru, Toshiro; Yamawaki, Shigeto

    2008-08-01

    Although the impaired extinction of traumatic memory is one of the hallmark symptoms of posttraumatic stress disorder (PTSD), the underlying mechanisms of impaired extinction are unclear and effective pharmacological interventions have not yet been developed. Single prolonged stress (SPS) has been proposed as an animal model of PTSD, since rats subjected to SPS (SPS rats) show enhanced negative feedback of the HPA axis and increased contextual fear, which are characteristics similar to those observed in patients with PTSD. In this study, using SPS rats, we examined (a) the ability of SPS to impair fear extinction, (b) whether D-cycloserine (DCS) can alleviate impaired fear extinction in SPS rats, and (c) the effect of SPS and/or DCS on the levels of N-methyl-D-aspartate (NMDA) receptor subunit mRNAs in the rat hippocampus during extinction training. SPS rats exhibited impaired fear extinction in the contextual fear test, which was alleviated by the repeated administration of DCS. The effect of enhanced extinction, induced by the administration of DCS to SPS rats, was maintained for one week following extinction training. SPS induced significant upregulation of the levels of NMDA receptor subunit mRNAs before and during the period of extinction training, while repeated administration of DCS eliminated the enhanced mRNA levels of NMDARs. Behavioral analyses indicated that SPS is an appropriate animal model of PTSD and that DCS may be effective in the treatment of PTSD. These findings suggest that DCS, irrespective of its mechanistic involvement in the enhancement of fear extinction, may help to reverse hippocampal plasticity, and thus reverse the NMDA compensatory alterations. PMID:17957211

  2. Identification and characterization of the NMDA receptor and its role in regulating reproduction in the cockroach Diploptera punctata.

    PubMed

    Huang, Juan; Hult, Ekaterina F; Marchal, Elisabeth; Tobe, Stephen S

    2015-04-01

    The NMDA receptor (NMDAR) plays important roles in excitatory neurotransmission and in the regulation of reproduction in mammals. NMDAR in insects comprises two subunits, NR1 and NR2. In this study, we identified two NR1 paralogs and eleven NR2 alternatively spliced variants in the cockroach Diploptera punctata. This is the first report of NR1 paralogs in insects. The tissue distributions and expression profiles of DpNR1A, DpNR1B and DpNR2 in different tissues were also investigated. Previous studies have demonstrated NMDA-stimulated biosynthesis of juvenile hormone (JH) in the corpora allata through the influx of extracellular Ca(2+) in Diploptera punctata. However, our data show that the transcript levels of DpNR1A, DpNR1B and DpNR2 were low in the corpora allata. MK-801, a high-affinity antagonist of NMDAR, did not show any effect on JH biosynthesis in vitro. In addition, neither partial knockdown of DpNR2 nor in vivo treatment with a physiologically relevant dose of MK-801 resulted in any significant change in JH biosynthesis or basal oocyte growth. Injection of animals with a high dose of MK-801 (30 µg per animal per injection), which paralyzed the animals for 4-5 h, resulted in a significant decrease in JH biosynthesis on days 4 and 5. However, the reproductive events during the first gonadotrophic cycle in female D. punctata were unaffected. Thus, NMDAR does not appear to play important roles in the regulation of JH biosynthesis or mediate reproduction of female D. punctata. PMID:25657209

  3. Association between the NMDA glutamate receptor GRIN2B gene and obsessive–compulsive disorder

    PubMed Central

    Alonso, Pino; Gratacós, Mónica; Segalàs, Cinto; Escaramís, Georgia; Real, Eva; Bayés, Mónica; Labad, Javier; López-Solà, Clara; Estivill, Xavier; Menchón, José M.

    2012-01-01

    Background Recent data from neuroimaging, genetic and clinical trials and animal models suggest a role for altered glutamatergic neurotransmission in the pathogenesis of obsessive–compulsive disorder (OCD). The aim of this study was to investigate whether variants in the GRIN2B gene, the gene encoding the NR2 subunit of the N-methyl-d-aspartate (NMDA) glutamate receptor, may contribute to genetic susceptibility to OCD or to different OCD subphenotypes. Methods Between 2003 and 2008, we performed a case–control association study in which we genotyped 10 tag single-nucleotide polymorphisms (SNPs) in the 3′ untranslated region (3′ UTR) of GRIN2B. We performed SNP association and haplotype analysis considering the OCD diagnosis and different OCD subphenotypes: early-onset OCD, comorbid tic disorders and OCD clinical symptom dimensions. Results We enrolled 225 patients with OCD and 279 controls recruited from the OCD Clinic at Bellvitge Hospital (Barcelona, Spain). No significant difference in the distribution of alleles or genotypes was detected between patients with OCD and controls. Nonetheless, on analyzing OCD subphenotypes, the rs1805476 SNP in male patients (95% confidence interval [CI] 1.37–4.22, p = 0.002) and a 4-SNP haplotype in the whole sample (rs1805476, rs1805501, rs1805502 and rs1805477; odds ratio 1.92, 95% CI 1.22–3.01; permutation p = 0.023) were significantly associated with the presence of contamination obsessions and cleaning compulsions. Limitations Study limitations included the risk of population stratification associated with the case–control design, use of psychiatrically unscreened blood donors as the control group, reduced sample size of participants with certain OCD subphenotypes and tested polymorphisms limited to 3′ UTR and exon 13 of GRIN2B. Conclusion Our results converge with recent data suggesting a possible contribution of glutamatergic variants to the genetic vulnerability to OCD or at least to certain OCD

  4. Involvement of hippocampal NMDA receptors in retrieval of spontaneous object recognition memory in rats.

    PubMed

    Iwamura, Etsushi; Yamada, Kazuo; Ichitani, Yukio

    2016-07-01

    The involvement of hippocampal N-methyl-d-aspartate (NMDA) receptors in the retrieval process of spontaneous object recognition memory was investigated. The spontaneous object recognition test consisted of three phases. In the sample phase, rats were exposed to two identical objects several (2-5) times in the arena. After the sample phase, various lengths of delay intervals (24h-6 weeks) were inserted (delay phase). In the test phase in which both the familiar and the novel objects were placed in the arena, rats' novel object exploration behavior under the hippocampal treatment of NMDA receptor antagonist, AP5, or vehicle was observed. With 5 exposure sessions in the sample phase (experiment 1), AP5 treatment in the test phase significantly decreased discrimination ratio when the delay was 3 weeks but not when it was one week. On the other hand, with 2 exposure sessions in the sample phase (experiment 2) in which even vehicle-injected control animals could not discriminate the novel object from the familiar one with a 3 week delay, AP5 treatment significantly decreased discrimination ratio when the delay was one week, but not when it was 24h. Additional experiment (experiment 3) showed that the hippocampal treatment of an α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor antagonist, NBQX, decreased discrimination ratio with all delay intervals tested (24h-3 weeks). Results suggest that hippocampal NMDA receptors play an important role in the retrieval of spontaneous object recognition memory especially when the memory trace weakens. PMID:27036649

  5. Metabotropic glutamate receptor 5, but not 1, modulates NMDA receptor-mediated activation of neuronal nitric oxide synthase.

    PubMed

    Llansola, Marta; Felipo, Vicente

    2010-03-01

    In cerebellar neurons in culture, activation of group I metabotropic glutamate receptors (mGluRs) prevents glutamate and NMDA-induced neuronal death, indicating that it interferes with the excitotoxic mechanisms leading to death. However, it is not known which step of these mechanisms is affected by mGluRs. The aims of this work were to assess: (a) whether activation of group I mGluRs (mGluR1 or mGluR5) impairs NMDA-induced activation of the glutamate-nitric oxide-cGMP pathway; (b) which mGluR (1 or 5) is responsible for this impairment and (c) whether impairment of the pathway occurs at the level of activation of soluble guanylate cyclase by nitric oxide or of activation of neuronal nitric oxide synthase (nNOS) by NMDA. It is shown that activation of mGluR1 enhances the function of the glutamate-nitric oxide-cGMP pathway by increasing activation of soluble guanylate cyclase by nitric oxide. In contrast, mGluR5 activation inhibits the glutamate-nitric oxide-cGMP pathway by reducing NMDA-induced activation of nNOS. This is due to reduced NMDA-induced increase in cAMP, reduced activation of Akt by cAMP and of nNOS by Akt. The impairment of activation of the glutamate-NO-cGMP pathway by activation of mGluR5 would contribute to its neuroprotective effect against excitotoxicity in cerebellar neurons in culture. PMID:20043967

  6. Modulation of the NMDA Receptor Through Secreted Soluble Factors.

    PubMed

    Cerpa, Waldo; Ramos-Fernández, Eva; Inestrosa, Nibaldo C

    2016-01-01

    Synaptic activity is a critical determinant in the formation and development of excitatory synapses in the central nervous system (CNS). The excitatory current is produced and regulated by several ionotropic receptors, including those that respond to glutamate. These channels are in turn regulated through several secreted factors that function as synaptic organizers. Specifically, Wnt, brain-derived neurotrophic factor (BDNF), fibroblast growth factor (FGF), and transforming growth factor (TGF) particularly regulate the N-methyl-D-aspartate receptor (NMDAR) glutamatergic channel. These factors likely regulate early embryonic development and directly control key proteins in the function of important glutamatergic channels. Here, we review the secreted molecules that participate in synaptic organization and discuss the cell signaling behind of this fine regulation. Additionally, we discuss how these factors are dysregulated in some neuropathologies associated with glutamatergic synaptic transmission in the CNS. PMID:25429903

  7. Antipsychotic treatment modulates glutamate transport and NMDA receptor expression.

    PubMed

    Zink, Mathias; Englisch, Susanne; Schmitt, Andrea

    2014-11-01

    Schizophrenia patients often suffer from treatment-resistant cognitive and negative symptoms, both of which are influenced by glutamate neurotransmission. Innovative therapeutic strategies such as agonists at metabotropic glutamate receptors or glycin reuptake inhibitors try to modulate the brain's glutamate network. Interactions of amino acids with monoamines have been described on several levels, and first- and second-generation antipsychotic agents (FGAs, SGAs) are known to exert modulatory effects on the glutamatergic system. This review summarizes the current knowledge on effects of FGAs and SGAs on glutamate transport and receptor expression derived from pharmacological studies. Such studies serve as a control for molecular findings in schizophrenia brain tissue and are clinically relevant. Moreover, they may validate animal models for psychosis, foster basic research on antipsychotic substances and finally lead to a better understanding of how monoaminergic and amino acid neurotransmissions are intertwined. In the light of these results, important differences dependent on antipsychotic substances, dosage and duration of treatment became obvious. While some post-mortem findings might be confounded with multifold drug effects, others are unlikely to be influenced by antipsychotic treatment and could represent important markers of schizophrenia pathophysiology. In similarity to the convergence of toxic and psychotomimetic effects of dopaminergic, serotonergic and anti-glutamatergic substances, the therapeutic mechanisms of SGAs might merge on a yet to be defined molecular level. In particular, serotonergic effects of SGAs, such as an agonism at 5HT1A receptors, represent important targets for further clinical research. PMID:25214389

  8. Ethanol enhances neurosteroidogenesis in hippocampal pyramidal neurons by paradoxical NMDA receptor activation.

    PubMed

    Tokuda, Kazuhiro; Izumi, Yukitoshi; Zorumski, Charles F

    2011-07-01

    Using an antibody against 5α-reduced neurosteroids, predominantly allopregnanolone, we found that immunostaining in the CA1 region of rat hippocampal slices was confined to pyramidal neurons. This neurosteroid staining was increased following 15 min administration of 60 mm but not 20 mm ethanol, and the enhancement was blocked by finasteride and dutasteride, selective inhibitors of 5α-reductase, a key enzyme required for allopregnanolone synthesis. Consistent with a prior report indicating that N-methyl-D-aspartate (NMDA) receptor (NMDAR) activation can promote steroid production, we observed that D-2-amino-5-phosphonovalerate (APV), a competitive NMDAR antagonist, blocked the effects of 60 mm ethanol on staining. We previously reported that 60 mm ethanol inhibits the induction of long-term potentiation (LTP), a cellular model for memory formation, in the CA1 region. In the present study, LTP inhibition by 60 mm ethanol was also overcome by both the 5α-reductase inhibitors and by APV. Furthermore, the effects of ethanol on neurosteroid production and LTP were mimicked by a low concentration of NMDA (1 μm), and the ability of NMDA to inhibit LTP and to enhance neurosteroid staining was reversed by finasteride and dutasteride, as well as by APV. These results indicate that ethanol paradoxically enhances GABAergic neurosteroid production by activation of unblocked NMDARs and that acute LTP inhibition by ethanol represents a form of NMDAR-mediated metaplasticity. PMID:21734282

  9. SNAP-25 Is a Target of Protein Kinase C Phosphorylation Critical to NMDA Receptor Trafficking

    PubMed Central

    Lau, C. Geoffrey; Takayasu, Yukihiro; Rodenas-Ruano, Alma; Paternain, Ana V.; Lerma, Juan; Bennett, Michael V. L.

    2010-01-01

    Protein kinase C (PKC) enhances NMDA receptor (NMDAR)-mediated currents and promotes NMDAR delivery to the cell surface via SNARE-dependent exocytosis. Although the mechanisms of PKC potentiation are established, the molecular target of PKC is unclear. Here we show that synaptosomal-associated protein of 25 kDa (SNAP-25), a SNARE protein, is functionally relevant to PKC-dependent NMDAR insertion, and identify serine residue-187 as the molecular target of PKC phosphorylation. Constitutively active PKC delivered via the patch pipette potentiated NMDA (but not AMPA) whole-cell currents in hippocampal neurons. Expression of RNAi targeting SNAP-25 or mutant SNAP-25(S187A) and/or acute disruption of the SNARE complex by treatment with BoNT A, BoNT B or SNAP-25 C-terminal blocking peptide abolished NMDAR potentiation. A SNAP-25 peptide and function-blocking antibody suppressed PKC potentiation of NMDA EPSCs at mossy fiber-CA3 synapses. These findings identify SNAP-25 as the target of PKC phosphorylation critical to PKC-dependent incorporation of synaptic NMDARs and document a postsynaptic action of this major SNARE protein relevant to synaptic plasticity. PMID:20053906

  10. Tandem Subunits Effectively Constrain GABAA Receptor Stoichiometry and Recapitulate Receptor Kinetics But Are Insensitive to GABAA Receptor-Associated Protein

    PubMed Central

    Boileau, Andrew J.; Pearce, Robert A.; Czajkowski, Cynthia

    2008-01-01

    GABAergic synapses likely contain multiple GABAA receptor subtypes, making postsynaptic currents difficult to dissect. However, even in heterologous expression systems, analysis of receptors composed of α, β, and γ subunits can be confounded by receptors expressed from α and β subunits alone. To produce recombinant GABAA receptors containing fixed subunit stoichiometry, we coexpressed individual subunits with a “tandem” α1 subunit linked to a β2 subunit. Cotransfection of the γ2 subunit with αβ-tandem subunits in human embryonic kidney 293 cells produced currents that were similar in their macroscopic kinetics, single-channel amplitudes, and pharmacology to overexpression of the γ subunit with nonlinked α1 and β2 subunits. Similarly, expression of α subunits together with αβ-tandem subunits produced receptors having physiological and pharmacological characteristics that closely matched cotransfection of α with β subunits. In this first description of tandem GABAA subunits measured with patch-clamp and rapid agonist application techniques, we conclude that incorporation of αβ-tandem subunits can be used to fix stoichiometry and to establish the intrinsic kinetic properties of α1β2 and α1β2γ2 receptors. We used this method to test whether the accessory protein GABAA receptor-associated protein (GABARAP) alters GABAA receptor properties directly or influences subunit composition. In recombinant receptors with fixed stoichiometry, coexpression of GABARAP-enhanced green fluorescent protein (EGFP) fusion protein had no effect on desensitization, deactivation, or diazepam potentiation of GABA-mediated currents. However, in α1β2γ2S transfections in which stoichiometry was not fixed, GABARAP-EGFP altered desensitization, deactivation, and diazepam potentiation of GABA-mediated currents. The data suggest that GABARAP does not alter receptor kinetics directly but by facilitating surface expression of αβγ receptors. PMID:16339017

  11. Anti-NMDA receptor encephalitis, autoimmunity, and psychosis.

    PubMed

    Kayser, Matthew S; Dalmau, Josep

    2016-09-01

    Anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis is a recently-discovered synaptic autoimmune disorder in which auto-antibodies target NMDARs in the brain, leading to their removal from the synapse. Patients manifest with prominent psychiatric symptoms - and in particular psychosis - early in the disease course. This presentation converges with long-standing evidence on multiple fronts supporting the glutamatergic model of schizophrenia. We review mechanisms underlying disease in anti-NMDAR encephalitis, and discuss its role in furthering our understanding of neural circuit dysfunction in schizophrenia. PMID:25458857

  12. Frequent rhabdomyolysis in anti-NMDA receptor encephalitis.

    PubMed

    Lim, Jung-Ah; Lee, Soon-Tae; Kim, Tae-Joon; Moon, Jangsup; Sunwoo, Jun-Sang; Byun, Jung-Ick; Jung, Keun-Hwa; Jung, Ki-Young; Chu, Kon; Lee, Sang Kun

    2016-09-15

    The aim of this study was to analyze the clinical presentation and provocation factors of rhabdomyolysis in anti-NMDAR encephalitis. Among the 16 patients with anti-NMDAR encephalitis in our institutional cohort, nine patients had elevated CK enzyme levels and clinical evidence of rhabdomyolysis. Rhabdomyolysis was more frequent after immunotherapy. The use of dopamine receptor blocker (DRB) increased the risk of rhabdomyolysis. None of the patients without rhabdomyolysis received DRBs. Rhabdomyolysis is a frequent complication in anti-NMDAR encephalitis and more common after immunotherapy and the use of DRBs increases the risk. Therefore, DRBs should be administered carefully in patients with anti-NMDAR encephalitis. PMID:27609293

  13. Venlafaxine increases cell proliferation and regulates DISC1, PDE4B and NMDA receptor 2B expression in the hippocampus in chronic mild stress mice.

    PubMed

    Zhang, Xinxin; Li, Xiaobai; Li, Min; Ren, Jintao; Yun, Ke; An, Yan; Lin, Lei; Zhang, Hailong

    2015-05-15

    Recent evidence has identified disrupted in schizophrenia-1 (DISC1) as an important genetic risk factor for the development of many psychiatric disorders, including major depressive disorders. In addition, studies using animal models have demonstrated that chronic stress affects hippocampal structure and function. However, the functional effects of chronic stress on DISC1 remain unknown. Using a chronic mild stress (CMS) paradigm, we investigated the effects of CMS on depressive-like behaviors, hippocampal cell proliferation, and hippocampal protein expression of DISC1, phosphodiesterase 4B (PDE4B) and N-methyl-d-aspartate receptor 2B subunit (NMDA receptor 2B), which may be involved in the regulation of DISC1 and neurogenesis. We also examined the effects and possible mechanisms of the antidepressant venlafaxine in CMS mice. CMS increased the expression of DISC1 and PDE4B. Chronic treatment with venlafaxine blocked the increases in these proteins, and also reversed the CMS-induced decrease in neurogenesis and NMDA receptor 2B protein in the hippocampus. These results suggest that DISC1 may play an important role in the etiology of depression and in the action of antidepressants. PMID:25769842

  14. Enhancement of postsynaptic GABAA and extrasynaptic NMDA receptor-mediated responses in the barrel cortex of Mecp2-null mice.

    PubMed

    Lo, Fu-Sun; Blue, Mary E; Erzurumlu, Reha S

    2016-03-01

    Rett syndrome (RTT) is a neurodevelopmental disorder that results from mutations in the X-linked gene for methyl-CpG-binding protein 2 (MECP2). The underlying cellular mechanism for the sensory deficits in patients with RTT is largely unknown. This study used the Bird mouse model of RTT to investigate sensory thalamocortical synaptic transmission in the barrel cortex of Mecp2-null mice. Electrophysiological results showed an excitation/inhibition imbalance, biased toward inhibition, due to an increase in efficacy of postsynaptic GABAA receptors rather than alterations in inhibitory network and presynaptic release properties. Enhanced inhibition impaired the transmission of tonic sensory signals from the thalamus to the somatosensory cortex. Previous morphological studies showed an upregulation of NMDA receptors in the neocortex of both RTT patients and Mecp2-null mice at early ages [Blue ME, Naidu S, Johnston MV. Ann Neurol 45: 541-545, 1999; Blue ME, Kaufmann WE, Bressler J, Eyring C, O'Driscoll C, Naidu S, Johnston MV. Anat Rec (Hoboken) 294: 1624-1634, 2011]. Although AMPA and NMDA receptor-mediated excitatory synaptic transmission was not altered in the barrel cortex of Mecp2-null mice, extrasynaptic NMDA receptor-mediated responses increased markedly. These responses were blocked by memantine, suggesting that extrasynaptic NMDA receptors play an important role in the pathogenesis of RTT. The results suggest that enhancement of postsynaptic GABAA and extrasynaptic NMDA receptor-mediated responses may underlie impaired somatosensation and that pharmacological blockade of extrasynaptic NMDA receptors may have therapeutic value for RTT. PMID:26683074

  15. A patient with encephalitis associated with NMDA receptor antibodies

    PubMed Central

    Sansing, Lauren H; Tüzün, Erdem; Ko, Melissa W; Baccon, Jennifer; Lynch, David R; Dalmau, Josep

    2007-01-01

    SUMMARY Background A 34-year-old woman presented with headache, feverish sensation and anxiety, rapidly followed by homicidal ideation, aggressive agitation, seizures, hypoventilation, hyperthermia and prominent autonomic instability requiring intubation and sedation. She developed episodes of hypotension and bradycardia with periods of asystole lasting up to 15 seconds. Upon weaning off sedation, her eyes opened but she was unresponsive to stimuli. There was muscle rigidity, frequent facial grimacing, rhythmic abdominal contractions, kicking motions of the legs, and intermittent dystonic postures of the right arm. Investigations Routine laboratory testing, toxicology screening, studies for autoimmune and infectious etiologies, brain MRI scan, lumbar puncture, electroencephalogram, whole-body CT scan, abdominal ultrasound, paraneoplastic and voltage-gated potassium channel antibody serologies, analysis of N-methyl-D-aspartate receptor antibodies. Diagnosis Paraneoplastic encephalitis associated with immature teratoma of the ovary and N-methyl-D-aspartate receptor antibodies. Management Intensive care, mechanical ventilation, antiepileptics, laparotomy and left salpingo-oophorectomy, corticosteroids, plasma exchange, intravenous immunoglobulin, cyclophosphamide, physical therapy, and chemotherapy. PMID:17479076

  16. Nicotinic α7 receptors enhance NMDA cognitive circuits in dorsolateral prefrontal cortex

    PubMed Central

    Yang, Yang; Paspalas, Constantinos D.; Jin, Lu E.; Picciotto, Marina R.; Arnsten, Amy F. T.; Wang, Min

    2013-01-01

    The cognitive function of the highly evolved dorsolateral prefrontal cortex (dlPFC) is greatly influenced by arousal state, and is gravely afflicted in disorders such as schizophrenia, where there are genetic insults in α7 nicotinic acetylcholine receptors (α7-nAChRs). A recent behavioral study indicates that ACh depletion from dlPFC markedly impairs working memory [Croxson PL, Kyriazis DA, Baxter MG (2011) Nat Neurosci 14(12):1510–1512]; however, little is known about how α7-nAChRs influence dlPFC cognitive circuits. Goldman-Rakic [Goldman-Rakic (1995) Neuron 14(3):477–485] discovered the circuit basis for working memory, whereby dlPFC pyramidal cells excite each other through glutamatergic NMDA receptor synapses to generate persistent network firing in the absence of sensory stimulation. Here we explore α7-nAChR localization and actions in primate dlPFC and find that they are enriched in glutamate network synapses, where they are essential for dlPFC persistent firing, with permissive effects on NMDA receptor actions. Blockade of α7-nAChRs markedly reduced, whereas low-dose stimulation selectively enhanced, neuronal representations of visual space. These findings in dlPFC contrast with the primary visual cortex, where nAChR blockade had no effect on neuronal firing [Herrero JL, et al. (2008) Nature 454(7208):1110–1114]. We additionally show that α7-nAChR stimulation is needed for NMDA actions, suggesting that it is key for the engagement of dlPFC circuits. As ACh is released in cortex during waking but not during deep sleep, these findings may explain how ACh shapes differing mental states during wakefulness vs. sleep. The results also explain why genetic insults to α7-nAChR would profoundly disrupt cognitive experience in patients with schizophrenia. PMID:23818597

  17. Opposite function of dopamine D1 and NMDA receptors in striatal cannabinoid-mediated signaling

    PubMed Central

    Daigle, Tanya L.; Wetsel, William C.; Caron, Marc G.

    2011-01-01

    It is well established that the cannabinoid and dopamine systems interact at various levels to regulate basal ganglia function. While it is well known that acute administration of cannabinoids to mice can modify dopamine-dependent behaviors, an understanding of the intraneuronal signaling pathways employed by these agents in the striatum is not well understood. Here we use knockout (KO) mouse models to examine the regulation of striatal ERK1/2 signaling by behaviorally relevant doses of cannabinoids. This cellular pathway has been implicated as a central mediator of drug reward and synaptic plasticity. In C57BL/6J mice, acute administration of cannabinoid agonists, HU-210 and Δ9-THC, promotes a dose- and time-dependent decrease in the phosphorylation of ERK1/2 in dorsal striatum. Co-administration of the CB1 cannabinoid receptor (CB1R) antagonist AM251 with HU-210 prevents ERK1/2 inactivation, indicating a requirement for activation of this receptor. In dopamine D1 receptor (D1R) KO animals treated with HU-210, the magnitude of the HU-210-dependent decrease in striatal ERK1/2 signaling is greater than in wild-type controls. In contrast, the HU-210 administration to NMDA receptor knockdown mice (NR1-Kd) was ineffective at promoting striatal ERK1/2 inactivation. Genetic deletion of other potential ERK1/2 mediators, the dopamine D2 receptors (D2R)s or βarrestin-1 or -2, did not affect HU-210-induced modulation of ERK1/2 signaling in the striatum. These results support the hypothesis that dopamine D1 receptors and NMDA receptors act in an opposite manner to regulate striatal CB1R signal transduction. PMID:22034973

  18. Chronic alcohol remodels prefrontal neurons and disrupts NMDA receptor-mediated fear extinction encoding

    PubMed Central

    Holmes, Andrew; Fitzgerald, Paul J.; MacPherson, Kathryn P.; DeBrouse, Lauren; Colacicco, Giovanni; Flynn, Shaun M.; Masneuf, Sophie; Pleil, Kristen E.; Li, Chia; Marcinkiewcz, Catherine A.; Kash, Thomas L.; Gunduz-Cinar, Ozge; Camp, Marguerite

    2012-01-01

    Alcoholism is frequently co-morbid with posttraumatic stress disorder (PTSD) but it is unclear how alcohol impacts neural circuits mediating recovery from trauma. We found that chronic intermittent ethanol (CIE) impaired fear extinction and remodeled the dendritic arbor of medial prefrontal cortical (mPFC) neurons in mice. CIE impaired extinction encoding by infralimbic (IL) mPFC neurons in vivo, and functionally downregulated burst-mediating NMDA GluN1 receptors. These findings suggest alcohol may increase risk for trauma-related anxiety disorders by disrupting mPFC-mediated extinction of fear. PMID:22941108

  19. Optical control of NMDA receptors with a diffusible photoswitch.

    PubMed

    Laprell, Laura; Repak, Emilienne; Franckevicius, Vilius; Hartrampf, Felix; Terhag, Jan; Hollmann, Michael; Sumser, Martin; Rebola, Nelson; DiGregorio, David A; Trauner, Dirk

    2015-01-01

    N-methyl-D-aspartate receptors (NMDARs) play a central role in synaptic plasticity, learning and memory, and are implicated in various neuronal disorders. We synthesized a diffusible photochromic glutamate analogue, azobenzene-triazole-glutamate (ATG), which is specific for NMDARs and functions as a photoswitchable agonist. ATG is inactive in its dark-adapted trans-isoform, but can be converted into its active cis-isoform using one-photon (near UV) or two-photon (740 nm) excitation. Irradiation with violet light photo-inactivates ATG within milliseconds, allowing agonist removal on the timescale of NMDAR deactivation. ATG is compatible with Ca(2+) imaging and can be used to optically mimic synaptic coincidence detection protocols. Thus, ATG can be used like traditional caged glutamate compounds, but with the added advantages of NMDAR specificity, low antagonism of GABAR-mediated currents, and precise temporal control of agonist delivery. PMID:26311290

  20. Optical control of NMDA receptors with a diffusible photoswitch

    PubMed Central

    Laprell, Laura; Repak, Emilienne; Franckevicius, Vilius; Hartrampf, Felix; Terhag, Jan; Hollmann, Michael; Sumser, Martin; Rebola, Nelson; DiGregorio, David A.; Trauner, Dirk

    2015-01-01

    N-methyl-D-aspartate receptors (NMDARs) play a central role in synaptic plasticity, learning and memory, and are implicated in various neuronal disorders. We synthesized a diffusible photochromic glutamate analogue, azobenzene-triazole-glutamate (ATG), which is specific for NMDARs and functions as a photoswitchable agonist. ATG is inactive in its dark-adapted trans-isoform, but can be converted into its active cis-isoform using one-photon (near UV) or two-photon (740 nm) excitation. Irradiation with violet light photo-inactivates ATG within milliseconds, allowing agonist removal on the timescale of NMDAR deactivation. ATG is compatible with Ca2+ imaging and can be used to optically mimic synaptic coincidence detection protocols. Thus, ATG can be used like traditional caged glutamate compounds, but with the added advantages of NMDAR specificity, low antagonism of GABAR-mediated currents, and precise temporal control of agonist delivery. PMID:26311290

  1. Reverse Translation of Clinical Electrophysiological Biomarkers in Behaving Rodents under Acute and Chronic NMDA Receptor Antagonism

    PubMed Central

    Sullivan, Elyse M; Timi, Patricia; Hong, L Elliot; O'Donnell, Patricio

    2015-01-01

    Electroencephalogram (EEG) stands out as a highly translational tool for psychiatric research, yet rodent and human EEG are not typically obtained in the same way. In this study we developed a tool to record skull EEG in awake-behaving rats in a similar manner to how human EEG are obtained and then used this technique to test whether acute NMDA receptor antagonism alters rodent EEG signals in a similar manner as in humans. Acute MK-801 treatment elevated gamma power and reduced beta band power, which closely mirrored EEG data from healthy volunteers receiving acute ketamine. To explore the mechanisms behind these oscillatory changes, we examined the effects of GABA-A receptor blockade, finding that picrotoxin (PTX) recapitulated the decrease in sound-evoked beta oscillations observed with acute MK-801, but did not produce changes in gamma band power. Chronic treatment with either PTX or MK-801 did not affect frequency-specific oscillatory activity when tested 24 h after the last drug injection, but decreased total broadband oscillatory power. Overall, this study validated a novel platform for recording rodent EEG and demonstrated similar oscillatory changes after acute NMDA receptor antagonism in both humans and rodents, suggesting that skull EEG may be a powerful tool for further translational studies. PMID:25176166

  2. Pharmacological Intervention of Hippocampal CA3 NMDA Receptors Impairs Acquisition and Long-Term Memory Retrieval of Spatial Pattern Completion Task

    ERIC Educational Resources Information Center

    Fellini, Laetitia; Florian, Cedrick; Courtey, Julie; Roullet, Pascal

    2009-01-01

    Pattern completion is the ability to retrieve complete information on the basis of incomplete retrieval cues. Although it has been demonstrated that this cognitive capacity depends on the NMDA receptors (NMDA-Rs) of the hippocampal CA3 region, the role played by these glutamatergic receptors in the pattern completion process has not yet been…

  3. Nucleus accumbens NMDA receptor activation regulates amphetamine cross-sensitization and deltaFosB expression following sexual experience in male rats.

    PubMed

    Beloate, Lauren N; Weems, Peyton W; Casey, Graham R; Webb, Ian C; Coolen, Lique M

    2016-02-01

    Sexual experience in male rats followed by a period of abstinence causes sensitization to d-Amphetamine (Amph) reward, evidenced by an increased conditioned place preference (CPP) for low doses of Amph. Moreover, sexual experience induces neural plasticity within the nucleus accumbens (NAc), including induction of deltaFosB, which plays a key role in Amph reward cross-sensitization. The NMDA receptor subunit NR1 is also upregulated by mating, but the functional relevance of NMDA receptors in sex experience-induced effects is unknown. Here, we examined the influence of intra-NAc MK 801 infusions on sex experience-induced NAc deltaFosB and cFos expression, as well as mating- and Amph-induced CPP in adult male rats. In experiment 1, males received MK 801 or saline into the NAc during each of 4 consecutive days of mating or handling and were tested for Amph CPP and experience-induced deltaFosB 10 days later. Intra-NAc MK 801 during sexual behavior prevented experience-induced increases in Amph CPP and NAc deltaFosB expression without affecting sexual behavior. In experiment 2, the effects of intra-NAc MK 801 on mating-induced CPP were examined by intra-NAc infusion of MK 801 or saline prior to mating on conditioning days. Intra-NAc MK 801 did not affect mating-induced CPP. Next, effects of intra-NAc MK 801 on mating-induced cFos immunoreactivity were examined. MK 801 prevented mating-induced cFos expression in NAc shell and core. Together, these results provide evidence that NAc NMDA receptor activation during sexual behavior plays a key role in mating-induced cFos and deltaFosB expression and subsequent experience-induced cross-sensitization to Amph reward. PMID:26391065

  4. Blocking NMDA receptors delays death in rats with acute liver failure by dual protective mechanisms in kidney and brain.

    PubMed

    Cauli, Omar; González-Usano, Alba; Cabrera-Pastor, Andrea; Gimenez-Garzó, Carla; López-Larrubia, Pilar; Ruiz-Sauri, Amparo; Hernández-Rabaza, Vicente; Duszczyk, Malgorzata; Malek, Michal; Lazarewicz, Jerzy W; Carratalá, Arturo; Urios, Amparo; Miguel, Alfonso; Torregrosa, Isidro; Carda, Carmen; Montoliu, Carmina; Felipo, Vicente

    2014-06-01

    Treatment of patients with acute liver failure (ALF) is unsatisfactory and mortality remains unacceptably high. Blocking NMDA receptors delays or prevents death of rats with ALF. The underlying mechanisms remain unclear. Clarifying these mechanisms will help to design more efficient treatments to increase patient's survival. The aim of this work was to shed light on the mechanisms by which blocking NMDA receptors delays rat's death in ALF. ALF was induced by galactosamine injection. NMDA receptors were blocked by continuous MK-801 administration. Edema and cerebral blood flow were assessed by magnetic resonance. The time course of ammonia levels in brain, muscle, blood, and urine; of glutamine, lactate, and water content in brain; of glomerular filtration rate and kidney damage; and of hepatic encephalopathy (HE) and intracranial pressure was assessed. ALF reduces kidney glomerular filtration rate (GFR) as reflected by reduced inulin clearance. GFR reduction is due to both reduced renal perfusion and kidney tubular damage as reflected by increased Kim-1 in urine and histological analysis. Blocking NMDA receptors delays kidney damage, allowing transient increased GFR and ammonia elimination which delays hyperammonemia and associated changes in brain. Blocking NMDA receptors does not prevent cerebral edema or blood-brain barrier permeability but reduces or prevents changes in cerebral blood flow and brain lactate. The data show that dual protective effects of MK-801 in kidney and brain delay cerebral alterations, HE, intracranial pressure increase and death. NMDA receptors antagonists may increase survival of patients with ALF by providing additional time for liver transplantation or regeneration. PMID:24338618

  5. Blockade of NMDA receptors reverses the depressant, but not anxiogenic effect of adolescence social isolation in mice.

    PubMed

    Haj-Mirzaian, Arya; Amiri, Shayan; Kordjazy, Nastaran; Rahimi-Balaei, Maryam; Haj-Mirzaian, Arvin; Marzban, Hassan; Aminzadeh, Azadeh; Dehpour, Ahmad Reza; Mehr, Shahram Ejtemaei

    2015-03-01

    Early life social isolation stress (SIS), a well-known chronic stress paradigm, is contributed to a number of pathophysiological and neurochemical changes including depression and anxiety. The underlying mechanisms for these disorders in socially isolated animals have not been fully cleared. Previous studies have shown that N-Methyl-d-aspartate (NMDA) receptor function is changed by social isolation condition. It is now well recognized that NMDA receptor blockade can exhibit antidepressant and anxiolytic actions. In our study, postnatal day 21-25 mice were randomly housed for 4 weeks under either social condition (SC) or isolated condition (IC). Then, animals were subjected to different behavioral experiments to investigate whether blockade of NMDA receptor resulted in behavioral alterations in animals. Social isolation stress induced depressive and anxiety-like behaviors in IC animals in comparison with SC mice. Also, we applied subeffective doses of antagonists including ketamine (1mg/kg), MK-801 (0.05mg/kg), and magnesium sulfate (10mg/kg) to both SC and IC mice prior to behavioral experiments. Administration of a single dose of all mentioned drugs did not affect the SC mice but modulated the depressant effects of SIS on IC mice. Administration of NMDA receptor antagonists decreased the immobility time in the forced swimming test as well as an increase in grooming behavior in splash test. However, anxiety-like behaviors in IC animals remained unchanged in hole-board test and open field test after blockade of NMDA receptors. Taken together, our results showed the possible involvement of the NMDA receptors in the depressive, but not anxiety-like behaviors induced by SIS. PMID:25592321

  6. Effects of NMDA-receptor antagonist treatment on c-fos expression in rat brain areas implicated in schizophrenia.

    PubMed

    Väisänen, Jussi; Ihalainen, Jouni; Tanila, Heikki; Castrén, Eero

    2004-12-01

    1. The noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonists produce behavioral responses that closely resemble both positive and negative symptoms of schizophrenia. These drugs also induce excitatory and neurotoxic effects in limbic cortical areas. 2. We have here mapped the brain areas which show increased activity in response to noncompetitive NMDA-receptor antagonist administration concentrating especially to those brain areas that have been suggested to be relevant in the pathophysiology of schizophrenia. 3. Rats were treated intraperitoneally with a NMDA-receptor antagonist MK801 and activation of brain areas was detected by monitoring the expression of c-fos mRNA by using in situ hybridization. 4. MK801 induced c-fos mRNA expression of in the retrosplenial, entorhinal, and prefrontal cortices. Lower c-fos expression was observed in the layer IV of the parietal and frontal cortex. In the thalamus, c-fos mRNA expression was detected in the midline nuclei and in the reticular nucleus but not in the dorsomedial nucleus. In addition, c-fos mRNA was expressed in the anterior olfactory nucleus, the ventral tegmental area, and in cerebellar granule neurons. 5. NMDA-receptor antagonist ketamine increased dopamine release in the parietal cortex, in the region where NMDA-receptor antagonist increased c-fos mRNA expression. 6. Thus, the psychotropic NMDA-receptor antagonist induced c-fos mRNA expression in most, but not all, brain areas implicated in the pathophysiology of schizophrenia. The high spatial resolution of in situ hybridization may help to define regions of interest for human imaging studies. PMID:15672679

  7. Concomitant manipulation of murine NMDA- and AMPA-receptors to produce pro-cognitive drug effects in mice.

    PubMed

    Vignisse, Julie; Steinbusch, Harry W M; Grigoriev, Vladimir; Bolkunov, Alexei; Proshin, Alexey; Bettendorff, Lucien; Bachurin, Sergey; Strekalova, Tatyana

    2014-02-01

    Bifunctional drug therapy targeting distinct receptor signalling systems can generate increased efficacy at lower concentrations compared to monofunctional therapy. Non-competitive blockade of the NMDA receptors or the potentiation of AMPA receptors is well documented to result in memory enhancement. Here, we compared the efficacy of the low-affinity NMDA receptor blocker memantine or the positive modulator of AMPA receptor QXX (in C57BL/6J at 1 or 5mg/kg, ip) with new derivatives of isothiourea (0.5-1 mg/kg, ip) that have bifunctional efficacy. Low-affinity NMDA blockade by these derivatives was achieved by introducing greater flexibility into the molecule, and AMPA receptor stimulation was produced by a sulfamide-containing derivative of isothiourea. Contextual learning was examined in a step-down avoidance task and extinction of contextual memory was studied in a fear-conditioning paradigm. Memantine enhanced contextual learning while QXX facilitated memory extinction; both drugs were effective at 5 mg/kg. The new derivative IPAC-5 elevated memory scores in both tasks at the dose 0.5 mg/kg and exhibited the lowest IC₅₀ values of NMDA receptor blockade and highest potency of AMPA receptor stimulation. Thus, among the new drugs tested, IPAC-5 replicated the properties of memantine and QXX in one administration with increased potency. Our data suggest that a concomitant manipulation of NMDA- and AMPA-receptors results in pro-cognitive effects and supports the concept bifunctional drug therapy as a promising strategy to replace monofunctional therapies with greater efficacy and improved compliance. PMID:23993168

  8. Septin 9 interacts with kinesin KIF17 and interferes with the mechanism of NMDA receptor cargo binding and transport.

    PubMed

    Bai, Xiaobo; Karasmanis, Eva P; Spiliotis, Elias T

    2016-03-15

    Intracellular transport involves the regulation of microtubule motor interactions with cargo, but the underlying mechanisms are not well understood. Septins are membrane- and microtubule-binding proteins that assemble into filamentous, scaffold-like structures. Septins are implicated in microtubule-dependent transport, but their roles are unknown. Here we describe a novel interaction between KIF17, a kinesin 2 family motor, and septin 9 (SEPT9). We show that SEPT9 associates directly with the C-terminal tail of KIF17 and interacts preferentially with the extended cargo-binding conformation of KIF17. In developing rat hippocampal neurons, SEPT9 partially colocalizes and comigrates with KIF17. We show that SEPT9 interacts with the KIF17 tail domain that associates with mLin-10/Mint1, a cargo adaptor/scaffold protein, which underlies the mechanism of KIF17 binding to the NMDA receptor subunit 2B (NR2B). Significantly, SEPT9 interferes with binding of the PDZ1 domain of mLin-10/Mint1 to KIF17 and thereby down-regulates NR2B transport into the dendrites of hippocampal neurons. Measurements of KIF17 motility in live neurons show that SEPT9 does not affect the microtubule-dependent motility of KIF17. These results provide the first evidence of an interaction between septins and a nonmitotic kinesin and suggest that SEPT9 modulates the interactions of KIF17 with membrane cargo. PMID:26823018

  9. Septin 9 interacts with kinesin KIF17 and interferes with the mechanism of NMDA receptor cargo binding and transport

    PubMed Central

    Bai, Xiaobo; Karasmanis, Eva P.; Spiliotis, Elias T.

    2016-01-01

    Intracellular transport involves the regulation of microtubule motor interactions with cargo, but the underlying mechanisms are not well understood. Septins are membrane- and microtubule-binding proteins that assemble into filamentous, scaffold-like structures. Septins are implicated in microtubule-dependent transport, but their roles are unknown. Here we describe a novel interaction between KIF17, a kinesin 2 family motor, and septin 9 (SEPT9). We show that SEPT9 associates directly with the C-terminal tail of KIF17 and interacts preferentially with the extended cargo-binding conformation of KIF17. In developing rat hippocampal neurons, SEPT9 partially colocalizes and comigrates with KIF17. We show that SEPT9 interacts with the KIF17 tail domain that associates with mLin-10/Mint1, a cargo adaptor/scaffold protein, which underlies the mechanism of KIF17 binding to the NMDA receptor subunit 2B (NR2B). Significantly, SEPT9 interferes with binding of the PDZ1 domain of mLin-10/Mint1 to KIF17 and thereby down-regulates NR2B transport into the dendrites of hippocampal neurons. Measurements of KIF17 motility in live neurons show that SEPT9 does not affect the microtubule-dependent motility of KIF17. These results provide the first evidence of an interaction between septins and a nonmitotic kinesin and suggest that SEPT9 modulates the interactions of KIF17 with membrane cargo. PMID:26823018

  10. Psychotic symptoms in anti-N-methyl-d-aspartate (NMDA) receptor encephalitis: A case report and challenges.

    PubMed

    Sharma, Pawan; Sagar, Rajesh; Patra, Bichitrananda; Saini, Lokesh; Gulati, Sheffali; Chakrabarty, Biswaroop

    2016-08-01

    Anti-N-methyl-d-aspartate (NMDA) receptor encephalitis, only recently first described, is an increasingly well-recognized inflammatory encephalitis that is seen in children and adults. An 11-year old girl admitted to the psychiatry ward with a presentation of acute psychosis was diagnosed with NMDA receptor encephalitis following neurology referral and was treated accordingly. This case highlights psychiatric manifestations in encephalitis and the need for the psychiatrist to have high index of suspicion when atypical symptoms (e.g., dyskinesia, seizure, fever etc.) present in acutely psychotic patients. PMID:27520914

  11. Overlapping demyelinating syndromes and anti-NMDA receptor encephalitis

    PubMed Central

    Titulaer, Maarten J.; Höftberger, Romana; Iizuka, Takahiro; Leypoldt, Frank; McCracken, Lindsey; Cellucci, Tania; Benson, Leslie A.; Shu, Huidy; Irioka, Takashi; Hirano, Makito; Singh, Gagandeep; Calvo, Alvaro Cobo; Kaida, Kenichi; Morales, Pamela S.; Wirtz, Paul W.; Yamamoto, Tomotaka; Reindl, Markus; Rosenfeld, Myrna R.; Graus, Francesc; Saiz, Albert; Dalmau, Josep

    2014-01-01

    Objective To report the clinical, radiological, and immunological association of demyelinating disorders with anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis. Methods Clinical and radiological analysis of a cohort of 691 patients with anti-NMDAR encephalitis. Determination of antibodies to NMDAR, aquaporin-4 (AQP4) and myelin oligodendrocyte glycoprotein (MOG) was performed using brain immunohistochemistry and cell-based assays. Results Twenty-three of 691 patients with anti-NMDAR encephalitis had prominent MRI and/or clinical features of demyelination. Group 1 included 12 patients in whom anti-NMDAR encephalitis was preceded or followed by independent episodes of NMO-spectrum disorder (5 cases, 4 anti-AQP4-positive), or brainstem or multifocal demyelinating syndromes (7 cases, all anti-MOG-positive). Group 2 included 11 patients in whom anti-NMDAR encephalitis occurred simultaneously with MRI and symptoms compatible with demyelination (5 AQ4-positive, 2 MOG-positive). Group 3 (136 controls) included 50 randomly selected patients with typical anti-NMDAR encephalitis, 56 with NMO, and 30 with multiple sclerosis: NMDAR-antibodies were detected only in the 50 anti-NMDAR patients, MOG-antibodies in 3/50 anti-NMDAR and 1/56 NMO patients, and AQP4-antibodies in 48/56 NMO and 1/50 anti-NMDAR patients (p<0.0001 for all comparisons with Groups 1 and 2). Most patients improved with immunotherapy, but compared with anti-NMDAR encephalitis the demyelinating episodes required more intensive therapy and resulted in more residual deficits. Only 1/23 NMDAR patients with signs of demyelination had ovarian teratoma compared with 18/50 anti-NMDAR controls (p=0.011) Interpretation Patients with anti-NMDAR encephalitis may develop concurrent or separate episodes of demyelinating disorders, and conversely patients with NMO or demyelinating disorders with atypical symptoms (e.g., dyskinesias, psychosis) may have anti-NMDAR encephalitis. PMID:24700511

  12. GABAB(1) receptor subunit isoforms differentially regulate stress resilience.

    PubMed

    O'Leary, Olivia F; Felice, Daniela; Galimberti, Stefano; Savignac, Hélène M; Bravo, Javier A; Crowley, Tadhg; El Yacoubi, Malika; Vaugeois, Jean-Marie; Gassmann, Martin; Bettler, Bernhard; Dinan, Timothy G; Cryan, John F

    2014-10-21

    Stressful life events increase the susceptibility to developing psychiatric disorders such as depression; however, many individuals are resilient to such negative effects of stress. Determining the neurobiology underlying this resilience is instrumental to the development of novel and more effective treatments for stress-related psychiatric disorders. GABAB receptors are emerging therapeutic targets for the treatment of stress-related disorders such as depression. These receptors are predominantly expressed as heterodimers of a GABAB(2) subunit with either a GABAB(1a) or a GABAB(1b) subunit. Here we show that mice lacking the GABAB(1b) receptor isoform are more resilient to both early-life stress and chronic psychosocial stress in adulthood, whereas mice lacking GABAB(1a) receptors are more susceptible to stress-induced anhedonia and social avoidance compared with wild-type mice. In addition, increased hippocampal expression of the GABAB(1b) receptor subunit is associated with a depression-like phenotype in the helpless H/Rouen genetic mouse model of depression. Stress resilience in GABAB(1b)(-/-) mice is coupled with increased proliferation and survival of newly born cells in the adult ventral hippocampus and increased stress-induced c-Fos activation in the hippocampus following early-life stress. Taken together, the data suggest that GABAB(1) receptor subunit isoforms differentially regulate the deleterious effects of stress and, thus, may be important therapeutic targets for the treatment of depression. PMID:25288769

  13. Differential antagonism of tetramethylenedisulfotetramine-induced seizures by agents acting at NMDA and GABAA receptors

    PubMed Central

    Shakarjian, Michael P.; Velíšková, Jana; Stanton, Patric K.; Velíšek, Libor

    2012-01-01

    Tetramethylenedisulfotetramine (TMDT) is a highly lethal neuroactive rodenticide responsible for many accidental and intentional poisonings in mainland China. Ease of synthesis, water solubility, potency, and difficulty to treat make TMDT a potential weapon for terrorist activity. We characterized TMDT-induced convulsions and mortality in male C57BL/6 mice. TMDT (ip) produced a continuum of twitches, clonic, and tonic-clonic seizures decreasing in onset latency and increasing in severity with increasing dose; 0.4 mg/kg was 100% lethal. The NMDA antagonist, ketamine (35 mg/kg) injected ip immediately after the first TMDT-induced seizure, did not change number of tonic-clonic seizures or lethality, but increased the number of clonic seizures. Doubling the ketamine dose decreased tonic-clonic seizures and eliminated lethality through a 60 min observation period. Treating mice with another NMDA antagonist, MK-801, 0.5 or 1 mg/kg ip, showed similar effects as low and high doses of ketamine, respectively, and prevented lethality, converting status epilepticus EEG activity to isolated interictal discharges. Treatment with these agents 15 min prior to TMDT administration did not increase their effectiveness. Post-treatment with the GABAA receptor allosteric enhancer diazepam (5 mg/kg) greatly reduced seizure manifestations and prevented lethality 60 min post-TMDT, but ictal events were evident in EEG recordings and, hours post-treatment, mice experienced status epilepticus and died. Thus, TMDT is a highly potent and lethal convulsant for which single-dose benzodiazepine treatment is inadequate in managing electrographic seizures or lethality. Repeated benzodiazepine dosing or combined application of benzodiazepines and NMDA receptor antagonists are more likely to be effective in treating TMDT poisoning. PMID:23022509

  14. Mutant GABA(A) receptor subunits in genetic (idiopathic) epilepsy.

    PubMed

    Hirose, Shinichi

    2014-01-01

    The γ-aminobutyric acid receptor type A (GABAA receptor) is a ligand-gated chloride channel that mediates major inhibitory functions in the central nervous system. GABAA receptors function mainly as pentamers containing α, β, and either γ or δ subunits. A number of antiepileptic drugs have agonistic effects on GABAA receptors. Hence, dysfunctions of GABAA receptors have been postulated to play important roles in the etiology of epilepsy. In fact, mutations or genetic variations of the genes encoding the α1, α6, β2, β3, γ2, or δ subunits (GABRA1, GABRA6, GABRB2, GABRB3, GABRG2, and GABRD, respectively) have been associated with human epilepsy, both with and without febrile seizures. Epilepsy resulting from mutations is commonly one of following, genetic (idiopathic) generalized epilepsy (e.g., juvenile myoclonic epilepsy), childhood absence epilepsy, genetic epilepsy with febrile seizures, or Dravet syndrome. Recently, mutations of GABRA1, GABRB2, and GABRB3 were associated with infantile spasms and Lennox-Gastaut syndrome. These mutations compromise hyperpolarization through GABAA receptors, which is believed to cause seizures. Interestingly, most of the insufficiencies are not caused by receptor gating abnormalities, but by complex mechanisms, including endoplasmic reticulum (ER)-associated degradation, nonsense-mediated mRNA decay, intracellular trafficking defects, and ER stress. Thus, GABAA receptor subunit mutations are now thought to participate in the pathomechanisms of epilepsy, and an improved understanding of these mutations should facilitate our understanding of epilepsy and the development of new therapies. PMID:25194483

  15. CaV3.2 calcium channels control NMDA receptor-mediated transmission: a new mechanism for absence epilepsy.

    PubMed

    Wang, Guangfu; Bochorishvili, Genrieta; Chen, Yucai; Salvati, Kathryn A; Zhang, Peng; Dubel, Steve J; Perez-Reyes, Edward; Snutch, Terrance P; Stornetta, Ruth L; Deisseroth, Karl; Erisir, Alev; Todorovic, Slobodan M; Luo, Jian-Hong; Kapur, Jaideep; Beenhakker, Mark P; Zhu, J Julius

    2015-07-15

    CaV3.2 T-type calcium channels, encoded by CACNA1H, are expressed throughout the brain, yet their general function remains unclear. We discovered that CaV3.2 channels control NMDA-sensitive glutamatergic receptor (NMDA-R)-mediated transmission and subsequent NMDA-R-dependent plasticity of AMPA-R-mediated transmission at rat central synapses. Interestingly, functional CaV3.2 channels primarily incorporate into synapses, replace existing CaV3.2 channels, and can induce local calcium influx to control NMDA transmission strength in an activity-dependent manner. Moreover, human childhood absence epilepsy (CAE)-linked hCaV3.2(C456S) mutant channels have a higher channel open probability, induce more calcium influx, and enhance glutamatergic transmission. Remarkably, cortical expression of hCaV3.2(C456S) channels in rats induces 2- to 4-Hz spike and wave discharges and absence-like epilepsy characteristic of CAE patients, which can be suppressed by AMPA-R and NMDA-R antagonists but not T-type calcium channel antagonists. These results reveal an unexpected role of CaV3.2 channels in regulating NMDA-R-mediated transmission and a novel epileptogenic mechanism for human CAE. PMID:26220996

  16. CaV3.2 calcium channels control NMDA receptor-mediated transmission: a new mechanism for absence epilepsy

    PubMed Central

    Wang, Guangfu; Bochorishvili, Genrieta; Chen, Yucai; Salvati, Kathryn A.; Zhang, Peng; Dubel, Steve J.; Perez-Reyes, Edward; Snutch, Terrance P.; Stornetta, Ruth L.; Deisseroth, Karl; Erisir, Alev; Todorovic, Slobodan M.; Luo, Jian-Hong; Kapur, Jaideep; Beenhakker, Mark P.; Zhu, J. Julius

    2015-01-01

    CaV3.2 T-type calcium channels, encoded by CACNA1H, are expressed throughout the brain, yet their general function remains unclear. We discovered that CaV3.2 channels control NMDA-sensitive glutamatergic receptor (NMDA-R)-mediated transmission and subsequent NMDA-R-dependent plasticity of AMPA-R-mediated transmission at rat central synapses. Interestingly, functional CaV3.2 channels primarily incorporate into synapses, replace existing CaV3.2 channels, and can induce local calcium influx to control NMDA transmission strength in an activity-dependent manner. Moreover, human childhood absence epilepsy (CAE)-linked hCaV3.2(C456S) mutant channels have a higher channel open probability, induce more calcium influx, and enhance glutamatergic transmission. Remarkably, cortical expression of hCaV3.2(C456S) channels in rats induces 2- to 4-Hz spike and wave discharges and absence-like epilepsy characteristic of CAE patients, which can be suppressed by AMPA-R and NMDA-R antagonists but not T-type calcium channel antagonists. These results reveal an unexpected role of CaV3.2 channels in regulating NMDA-R-mediated transmission and a novel epileptogenic mechanism for human CAE. PMID:26220996

  17. Target-Specific Expression of Presynaptic NMDA Receptors in Neocortical Microcircuits

    PubMed Central

    Buchanan, Katherine A.; Blackman, Arne V.; Moreau, Alexandre W.; Elgar, Dale; Costa, Rui P.; Lalanne, Txomin; Tudor Jones, Adam A.; Oyrer, Julia; Sjöström, P. Jesper

    2012-01-01

    Summary Traditionally, NMDA receptors are located postsynaptically; yet, putatively presynaptic NMDA receptors (preNMDARs) have been reported. Although implicated in controlling synaptic plasticity, their function is not well understood and their expression patterns are debated. We demonstrate that, in layer 5 of developing mouse visual cortex, preNMDARs specifically control synaptic transmission at pyramidal cell inputs to other pyramidal cells and to Martinotti cells, while leaving those to basket cells unaffected. We also reveal a type of interneuron that mediates ascending inhibition. In agreement with synapse-specific expression, we find preNMDAR-mediated calcium signals in a subset of pyramidal cell terminals. A tuned network model predicts that preNMDARs specifically reroute information flow in local circuits during high-frequency firing, in particular by impacting frequency-dependent disynaptic inhibition mediated by Martinotti cells, a finding that we experimentally verify. We conclude that postsynaptic cell type determines presynaptic terminal molecular identity and that preNMDARs govern information processing in neocortical columns. PMID:22884329

  18. SP-8203 shows neuroprotective effects and improves cognitive impairment in ischemic brain injury through NMDA receptor.

    PubMed

    Noh, Su-Jin; Lee, Jong Min; Lee, Ki Sung; Hong, Hyun Su; Lee, Chul Kyu; Cho, Il Hwan; Kim, Hye-Sun; Suh, Yoo-Hun

    2011-11-01

    The extracts of earth worms, Eisenia andrei, have been used as a therapeutic agent for stroke in the traditional medicine. It is also reported that the protease fraction separated from the extracts has strong anti-thrombotic activity. Besides anti-thrombotic actions, we found that SP-8203, N-[3-(2,4-dioxo-1,4-dihydro-2H-quinazolin-3-yl)propyl]-N-{4-[3-(2,4-dioxo-1,4-dihydro-2H-quinazolin-3-yl)propylamino]butyl}acetamide, derived from the extracts of earth worms blocked N-methyl-(D)-aspartate (NMDA) receptor-mediated excitotoxicity in a competitive manner. The neuroprotective effects of SP-8203 were attributable to prevention of Ca(2+) influx through NMDA receptors. The systemic administration of SP-8203 markedly reduced neuronal death following middle cerebral artery occlusion in rats. SP-8203 significantly improved spatial learning and memory in the water maze test. These results provided strong pharmacological basis for its potential therapeutic roles in cerebral ischemia. PMID:21835192

  19. Synaptic NMDA receptor stimulation activates PP1 by inhibiting its phosphorylation by Cdk5

    PubMed Central

    Hou, Hailong; Sun, Lu; Siddoway, Benjamin A.; Petralia, Ronald S.; Yang, Hongtian; Gu, Hua; Nairn, Angus C.

    2013-01-01

    The serine/threonine protein phosphatase protein phosphatase 1 (PP1) is known to play an important role in learning and memory by mediating local and downstream aspects of synaptic signaling, but how PP1 activity is controlled in different forms of synaptic plasticity remains unknown. We find that synaptic N-methyl-d-aspartate (NMDA) receptor stimulation in neurons leads to activation of PP1 through a mechanism involving inhibitory phosphorylation at Thr320 by Cdk5. Synaptic stimulation led to proteasome-dependent degradation of the Cdk5 regulator p35, inactivation of Cdk5, and increased auto-dephosphorylation of Thr320 of PP1. We also found that neither inhibitor-1 nor calcineurin were involved in the control of PP1 activity in response to synaptic NMDA receptor stimulation. Rather, the PP1 regulatory protein, inhibitor-2, formed a complex with PP1 that was controlled by synaptic stimulation. Finally, we found that inhibitor-2 was critical for the induction of long-term depression in primary neurons. Our work fills a major gap regarding the regulation of PP1 in synaptic plasticity. PMID:24189275

  20. The NMDA Receptor Promotes Sleep in the Fruit Fly, Drosophila melanogaster.

    PubMed

    Tomita, Jun; Ueno, Taro; Mitsuyoshi, Madoka; Kume, Shoen; Kume, Kazuhiko

    2015-01-01

    Considerable evidence indicates that sleep is essential for learning and memory. Drosophila melanogaster has emerged as a novel model for studying sleep. We previously found a short sleeper mutant, fumin (fmn), and identified its mutation in the dopamine transporter gene. We reported similarities in the molecular basis of sleep and arousal regulation between mammals and Drosophila. In aversive olfactory learning tasks, fmn mutants demonstrate defective memory retention, which suggests an association between sleep and memory. In an attempt to discover additional sleep related genes in Drosophila, we carried out a microarray analysis comparing mRNA expression in heads of fmn and control flies and found that 563 genes are differentially expressed. Next, using the pan-neuronal Gal4 driver elav-Gal4 and UAS-RNA interference (RNAi) to knockdown individual genes, we performed a functional screen. We found that knockdown of the NMDA type glutamate receptor channel gene (Nmdar1) (also known as dNR1) reduced sleep. The NMDA receptor (NMDAR) plays an important role in learning and memory both in Drosophila and mammals. The application of the NMDAR antagonist, MK-801, reduced sleep in control flies, but not in fmn. These results suggest that NMDAR promotes sleep regulation in Drosophila. PMID:26023770

  1. The NMDA Receptor Promotes Sleep in the Fruit Fly, Drosophila melanogaster

    PubMed Central

    Tomita, Jun; Ueno, Taro; Mitsuyoshi, Madoka; Kume, Shoen; Kume, Kazuhiko

    2015-01-01

    Considerable evidence indicates that sleep is essential for learning and memory. Drosophila melanogaster has emerged as a novel model for studying sleep. We previously found a short sleeper mutant, fumin (fmn), and identified its mutation in the dopamine transporter gene. We reported similarities in the molecular basis of sleep and arousal regulation between mammals and Drosophila. In aversive olfactory learning tasks, fmn mutants demonstrate defective memory retention, which suggests an association between sleep and memory. In an attempt to discover additional sleep related genes in Drosophila, we carried out a microarray analysis comparing mRNA expression in heads of fmn and control flies and found that 563 genes are differentially expressed. Next, using the pan-neuronal Gal4 driver elav-Gal4 and UAS-RNA interference (RNAi) to knockdown individual genes, we performed a functional screen. We found that knockdown of the NMDA type glutamate receptor channel gene (Nmdar1) (also known as dNR1) reduced sleep. The NMDA receptor (NMDAR) plays an important role in learning and memory both in Drosophila and mammals. The application of the NMDAR antagonist, MK-801, reduced sleep in control flies, but not in fmn. These results suggest that NMDAR promotes sleep regulation in Drosophila. PMID:26023770

  2. Involvement of normalized NMDA receptor and mTOR-related signaling in rapid antidepressant effects of Yueju and ketamine on chronically stressed mice

    PubMed Central

    Tang, Juanjuan; Xue, Wenda; Xia, Baomei; Ren, Li; Tao, Weiwei; Chen, Chang; Zhang, Hailou; Wu, Ruyan; Wang, Qisheng; Wu, Haoxin; Duan, Jinao; Chen, Gang

    2015-01-01

    Yueju, a Traditional Chinese Medicine formula, exhibited fast-onset antidepressant responses similar to ketamine. This study focused on assessing the rapid and persistent antidepressant efficacy of Yueju and ketamine in chronically stressed mice and its association with alternations in prefrontal N-methyl-D-aspartate (NMDA) receptor and mammalian target of rapamycin (mTOR)-related activity. Chronic mild stress (CMS) led to deficits in sucrose preference test (SPT), forced swim test, tail suspension test, and novelty-suppressed feeding test, which were improved differently by acute Yueju or ketamine administration. The improvement in SPT started as soon as 2 hours post Yueju and ketamine but lasted for 6 days only by Yueju. Body weight was regained by Yueju more than ketamine at post-drug administration day (PAD) 6. CMS decreased phosphorylation of the mTOR effectors 4E-BP1 and p70S6K, their upstream regulators ERK and Akt, and downstream targets including synaptic protein GluR1. Yueju or ketamine reversed these changes at PAD 2, but only Yueju reversed phosphor-Akt at PAD 6. CMS selectively and lastingly increased NMDA receptor subunit NR1 expression, which was reversed by ketamine or Yueju at PAD 2 but only by Yueju at PAD 6. These findings suggest that NR1 and Akt/mTOR signaling are important therapeutic targets for depression. PMID:26315757

  3. Stereotactic injection of cerebrospinal fluid from anti-NMDA receptor encephalitis into rat dentate gyrus impairs NMDA receptor function.

    PubMed

    Würdemann, Till; Kersten, Maxi; Tokay, Tursonjan; Guli, Xiati; Kober, Maria; Rohde, Marco; Porath, Katrin; Sellmann, Tina; Bien, Christian G; Köhling, Rüdiger; Kirschstein, Timo

    2016-02-15

    Autoimmune encephalitis is increasingly recognized in patients with otherwise unexplained encephalopathy with epilepsy. Among these, patients with anti-N-methyl D-aspartate receptor (NMDAR) encephalitis present epileptic seizures, memory deficits, and psychiatric symptoms. However, the functional consequences of such autoantibodies are poorly understood. In order to investigate the pathophysiology of this disease, we stereotactically injected either cerebrospinal fluid (CSF) from three anti-NMDAR encephalitis patients or commercially available anti-NMDAR1 into the dentate gyrus of adult female rats. Control animals were injected with either CSF obtained from three epilepsy patients (ganglioglioma, posttraumatic epilepsy, focal cortical dysplasia) lacking anti-NMDAR or saline. Intracellular recordings from dentate gyrus granule cells showed a significant reduction of the NMDAR-evoked excitatory postsynaptic potentials (NMDAR-EPSPs) in animals treated with anti-NMDAR. As a consequence of this, action potential firing in these cells by NMDAR-EPSPs was significantly impaired. Long-term potentiation in the dentate gyrus was also significantly reduced in rats injected with anti-NMDAR as compared to control animals. This was accompanied by a significantly impaired learning performance in the Morris water maze hidden platform task when the animals had been injected with anti-NMDAR antibody-containing CSF. Our findings suggest that anti-NMDAR lead to reduced NMDAR function in vivo which could contribute to the memory impairment found in patients with anti-NMDAR encephalitis. PMID:26721688

  4. Diurnal inhibition of NMDA-EPSCs at rat hippocampal mossy fibre synapses through orexin-2 receptors

    PubMed Central

    Perin, Martina; Longordo, Fabio; Massonnet, Christine; Welker, Egbert; Lüthi, Anita

    2014-01-01

    Diurnal release of the orexin neuropeptides orexin-A (Ox-A, hypocretin-1) and orexin-B (Ox-B, hypocretin-2) stabilises arousal, regulates energy homeostasis and contributes to cognition and learning. However, whether cellular correlates of brain plasticity are regulated through orexins, and whether they do so in a time-of-day-dependent manner, has never been assessed. Immunohistochemically we found sparse but widespread innervation of hippocampal subfields through Ox-A- and Ox-B-containing fibres in young adult rats. The actions of Ox-A were studied on NMDA receptor (NMDAR)-mediated excitatory synaptic transmission in acute hippocampal slices prepared around the trough (Zeitgeber time (ZT) 4–8, corresponding to 4–8 h into the resting phase) and peak (ZT 23) of intracerebroventricular orexin levels. At ZT 4–8, exogenous Ox-A (100 nm in bath) inhibited NMDA receptor-mediated excitatory postsynaptic currents (NMDA-EPSCs) at mossy fibre (MF)–CA3 (to 55.6 ± 6.8% of control, P = 0.0003) and at Schaffer collateral–CA1 synapses (70.8 ± 6.3%, P = 0.013), whereas it remained ineffective at non-MF excitatory synapses in CA3. Ox-A actions were mediated postsynaptically and blocked by the orexin-2 receptor (OX2R) antagonist JNJ10397049 (1 μm), but not by orexin-1 receptor inhibition (SB334867, 1 μm) or by adrenergic and cholinergic antagonists. At ZT 23, inhibitory effects of exogenous Ox-A were absent (97.6 ± 2.9%, P = 0.42), but reinstated (87.2 ± 3.3%, P = 0.002) when endogenous orexin signalling was attenuated for 5 h through i.p. injections of almorexant (100 mg kg−1), a dual orexin receptor antagonist. In conclusion, endogenous orexins modulate hippocampal NMDAR function in a time-of-day-dependent manner, suggesting that they may influence cellular plasticity and consequent variations in memory performance across the sleep–wake cycle. PMID:25085886

  5. Ethanol (EtOH) inhibition of NMDA-activated ion current is not voltage-dependent and EtOH does not interact with other binding sites on the NMDA receptor/ionophore complex

    SciTech Connect

    Lovinger, D.M.; White, G.; Weight, F.F. )

    1990-02-26

    Recent studies indicate that intoxicating concentrations of EtOH inhibit neuronal responses to activation of NMDA-type glutamate receptors. The authors have observed that the potency of different alcohols for inhibiting NMDA-activated ion current in hippocampal neurons increases as a function of increasing hydrophobicity, suggesting that EtOH acts at a hydrophobic site. To further characterize the mechanisms of this effect, the authors examined the voltage-dependence of the EtOH inhibition of NMDA-activated ion current as well as potential interactions of EtOH with other effectors of the NMDA receptor/ionophore complex. The amount of inhibition of peak NMDA-activated current by 50 mM EtOH did not differ over a range of membrane potentials from {minus}60 to +60 mV, and EtOH did not alter the reversal potential of NMDA-activated current. The percent inhibition observed in the presence of 10-100 mM EtOH did not differ with NMDA concentrations from 10-100 {mu}M. The percent inhibition by 50 mM EtOH (30-48%) did not differ in the absence or presence of the channel blockers Mg{sup 2+} (50-500 {mu}M), Zn{sup 2+} (5 and 20 {mu}M) or ketamine (2 and 10 {mu}M), or with increasing concentrations of the NMDA receptor cofactor glycine (0.01-1 {mu}M). These data indicate that: (i) EtOH does not change the ion selectivity of the ionophore, and (ii) EtOH does not appear to interact with previously described binding sites on the NMDA receptor/ionophore complex.

  6. Interferon-gamma potentiates NMDA receptor signaling in spinal dorsal horn neurons via microglia–neuron interaction

    PubMed Central

    Sonekatsu, Mayumi; Yamanaka, Manabu; Nishio, Naoko; Tsutsui, Shunji; Yamada, Hiroshi; Yoshida, Munehito; Nakatsuka, Terumasa

    2016-01-01

    Background Glia–neuron interactions play an important role in the development of neuropathic pain. Expression of the pro-inflammatory cytokne →cytokine Interferon-gamma (IFNγ) is upregulated in the dorsal horn after peripheral nerve injury, and intrathecal IFNγ administration induces mechanical allodynia in rats. A growing body of evidence suggests that IFNγ might be involved in the mechanisms of neuropathic pain, but its effects on the spinal dorsal horn are unclear. We performed blind whole-cell patch-clamp recording to investigate the effect of IFNγ on postsynaptic glutamate-induced currents in the substantia gelatinosa neurons of spinal cord slices from adult male rats. Results IFNγ perfusion significantly enhanced the amplitude of NMDA-induced inward currents in substantia gelatinosa neurons, but did not affect AMPA-induced currents. The facilitation of NMDA-induced current by IFNγ was inhibited by bath application of an IFNγ receptor-selective antagonist. Adding the Janus activated kinase inhibitor tofacitinib to the pipette solution did not affect the IFNγ-induced facilitation of NMDA-induced currents. However, the facilitatory effect of IFNγ on NMDA-induced currents was inhibited by perfusion of the microglial inhibitor minocycline. These results suggest that IFNγ binds the microglial IFNγ receptor and enhances NMDA receptor activity in substantia gelatinosa neurons. Next, to identify the effector of signal transmission from microglia to dorsal horn neurons, we added an inhibitor of G proteins, GDP-β-S, to the pipette solution. In a GDP-β-S–containing pipette solution, IFNγ-induced potentiation of the NMDA current was significantly suppressed after 30 min. In addition, IFNγ-induced potentiation of NMDA currents was blocked by application of a selective antagonist of CCR2, and its ligand CCL2 increased NMDA-induced currents. Conclusion Our findings suggest that IFNγ enhance the amplitude of NMDA-induced inward currents in substantia

  7. Synaptic commitment: developmentally regulated reciprocal changes in hippocampal granule cell NMDA and AMPA receptors over the lifespan.

    PubMed

    Yang, Zhiyong; Krause, Michael; Rao, Geeta; McNaughton, Bruce L; Barnes, C A

    2008-06-01

    Synaptic transmission in hippocampal field CA1 is largely N-methyl-d-aspartate receptor (NMDA(R)) dependent during the early postnatal period. It becomes increasingly mediated by alpha-amino-3-hydroxy-5-methylisoxazole-4-proprionate (AMPA) receptors until an adult ratio of AMPA to NMDA receptors is achieved. It is shown here that increases in the AMPA receptor (AMPA(R))-mediated field potential response continue over the life span of the F-344 rat at the perforant path-granule cell synapse in the dentate gyrus. In contrast, the NMDA(R)-dependent component of the response decreases with age between 1 and 27 mo, leading to an increase of AMPA(R)/NMDA(R) ratio with age. One possible explanation of this age difference is that the AMPA(R)/NMDA(R) ratio can be modified by experience. To test the idea that the changed ratio is caused by the old rats' longer lives, an intensive 10-mo period of enrichment treatment was given to a group of animals, beginning at 3 mo of age. Compared with animals housed in standard cages, the enrichment treatment did not alter the glutamatergic response ratio measured with field potential recording methods. These data provide support for the conclusion that the observed change with age is developmentally regulated rather than experience dependent. Given the role of the NMDA(R) in synaptic plasticity, these changes suggest a progressive commitment of perforant path synapses to particular weights over the life span. One possible implication of this effect includes preservation of selected memories, ultimately at the expense of a reduced capacity to store new information. PMID:18417629

  8. Overactivation of NR2B-containing NMDA receptors through entorhinal-hippocampal connection initiates accumulation of hyperphosphorylated tau in rat hippocampus after transient middle cerebral artery occlusion.

    PubMed

    Xu, Cheng-Shi; Liu, An-Chun; Chen, Juan; Pan, Zhi-Yong; Wan, Qi; Li, Zhi-Qiang; Wang, Ze-Fen

    2015-08-01

    Middle cerebral artery occlusion (MCAO) induces secondary damages in the hippocampus that is remote from primary ischemic regions. Tau hyperphosphorylation is an important risk for neurodegenerative diseases. Increased tau phosphorylation has been identified in ischemic cortex, but little is known regarding the changes in the hippocampus. We showed that unilateral transient MCAO induced accumulation of hyperphosphorylated tau and concurrent dephosphorylation of glycogen synthase kinase-3β at Ser 9 in the ipsilateral hippocampus. These MCAO-induced changes were not reproduced when glutamatergic inputs from the entorhinal cortex to the hippocampus were transected; however, the changes were mimicked by intrahippocampal N-methyl-d-aspartate (NMDA) administration. Inhibition of NMDA receptor (NMDAR) subunit NR2B, but not NR2A activity in the hippocampus attenuated the accumulation of hyperphosphorylated tau and spatial cognitive impairment in MCAO rats. Together, our data suggest that overactivation of NR2B-containing NMDARs through entorhinal-hippocampal connection plays an important role in the accumulation of hyperphosphorylated tau in the hippocampus following MCAO. Glycogen synthase kinase-3β is an important protein kinase involved in NMDARs-mediated tau hyperphosphorylation. This study indicates that early inhibition of NR2B-containing NMDARs may represent a potential strategy to prevent or delay the occurrence of post-stroke dementia. Middle cerebral artery occlusion induces secondary damage in the hippocampus that is remote from primary ischemic regions. We propose that excessive activation of NR2B-containing NMDA receptors through entorhinal-hippocampal connection initiated the accumulation of hyperphosphorylated tau in the hippocampus, which subsequently induced cognitive deficit. This study provides new insights into the prospects of NR2B inhibition in stoke therapy. PMID:25903928

  9. Combined stimulation of the glycine and polyamine sites of the NMDA receptor attenuates NMDA blockade-induced learning deficits of rats in a 14-unit T-maze.

    PubMed

    Meyer, R C; Knox, J; Purwin, D A; Spangler, E L; Ingram, D K

    1998-02-01

    The present study examined the effects of multi-site activation of the glycine and polyamine sites of the NMDA receptor on memory formation in rats learning a 14-unit T-maze task. The competitive NMDA receptor antagonist, (+/-)-3-(2-carboxypiperazine-4-yl)-propyl-1-phosphonic acid (CPP, 9 mg/kg), was used to impair learning. The objectives were two-fold: (1) to investigate the effects of independent stimulation of the strychnine-insensitive glycine site or the polyamine site; (2) to investigate the effects of simultaneous activation of these two sites. Male, Fischer-344 rats were pretrained to a criterion of 13 out of 15 shock avoidances in a straight runway, and 24 h later were trained in a 14-unit T-maze that also required shock avoidance. Prior to maze training, rats received intraperitoneal (i.p.) injections of saline, saline plus CPP, CPP plus the glycine agonist, D-cycloserine (DCS, 30 or 40 mg/kg), CPP plus the polyamine agonist, spermine (SPM, 2.5 or 5 mg/kg), or CPP plus a combination of DCS (7.5 mg/kg) and SPM (0.625 mg/kg). Individual administration of either DCS or SPM attenuated the CPP-induced maze learning impairment in a dose-dependent manner. However, the combined treatment with both DCS and SPM completely reversed the learning deficit at doses five-fold less than either drug given alone. These findings provide additional evidence that the glycine and polyamine modulatory sites of the NMDA receptor are involved in memory formation. Furthermore, the potent synergistic effect resulting from combined activation of the glycine and polyamine sites would suggest a stronger interaction between these two sites than previously considered, and might provide new therapeutic approaches for enhancing glutamatergic function. PMID:9498733

  10. Slow-pressor angiotensin II hypertension and concomitant dendritic NMDA receptor trafficking in estrogen receptor β-containing neurons of the mouse hypothalamic paraventricular nucleus are sex and age dependent.

    PubMed

    Marques-Lopes, Jose; Van Kempen, Tracey; Waters, Elizabeth M; Pickel, Virginia M; Iadecola, Costantino; Milner, Teresa A

    2014-09-01

    The incidence of hypertension increases after menopause. Similar to humans, "slow-pressor" doses of angiotensin II (AngII) increase blood pressure in young males, but not in young female mice. However, AngII increases blood pressure in aged female mice, paralleling reproductive hormonal changes. These changes could influence receptor trafficking in central cardiovascular circuits and contribute to hypertension. Increased postsynaptic N-methyl-D-aspartate (NMDA) receptor activity in the hypothalamic paraventricular nucleus (PVN) is crucial for the sympathoexcitation driving AngII hypertension. Estrogen receptors β (ERβs) are present in PVN neurons. We tested the hypothesis that changes in ovarian hormones with age promote susceptibility to AngII hypertension, and influence NMDA receptor NR1 subunit trafficking in ERβ-containing PVN neurons. Transgenic mice expressing enhanced green fluorescent protein (EGFP) in ERβ-containing cells were implanted with osmotic minipumps delivering AngII (600 ng/kg/min) or saline for 2 weeks. AngII increased blood pressure in 2-month-old males and 18-month-old females, but not in 2-month-old females. By electron microscopy, NR1-silver-intensified immunogold (SIG) was mainly in ERβ-EGFP dendrites. At baseline, NR1-SIG density was greater in 2-month-old females than in 2-month-old males or 18-month-old females. After AngII infusion, NR1-SIG density was decreased in 2-month-old females, but increased in 2-month-old males and 18-month-old females. These findings suggest that, in young female mice, NR1 density is decreased in ERβ-PVN dendrites thus reducing NMDA receptor activity and preventing hypertension. Conversely, in young males and aged females, NR1 density is upregulated in ERβ-PVN dendrites and ultimately leads to the neurohumoral dysfunction driving hypertension. PMID:24639345

  11. NMDA receptor activation and calpain contribute to disruption of dendritic spines by the stress neuropeptide CRH.

    PubMed

    Andres, Adrienne L; Regev, Limor; Phi, Lucas; Seese, Ronald R; Chen, Yuncai; Gall, Christine M; Baram, Tallie Z

    2013-10-23

    The complex effects of stress on learning and memory are mediated, in part, by stress-induced changes in the composition and structure of excitatory synapses. In the hippocampus, the effects of stress involve several factors including glucocorticoids and the stress-released neuropeptide corticotropin-releasing hormone (CRH), which influence the integrity of dendritic spines and the structure and function of the excitatory synapses they carry. CRH, at nanomolar, presumed-stress levels, rapidly abolishes short-term synaptic plasticity and destroys dendritic spines, yet the mechanisms for these effects are not fully understood. Here we tested the hypothesis that glutamate receptor-mediated processes, which shape synaptic structure and function, are engaged by CRH and contribute to spine destabilization. In cultured rat hippocampal neurons, CRH application reduced dendritic spine density in a time- and dose-dependent manner, and this action depended on the CRH receptor type 1. CRH-mediated spine loss required network activity and the activation of NMDA, but not of AMPA receptors; indeed GluR1-containing dendritic spines were resistant to CRH. Downstream of NMDA receptors, the calcium-dependent enzyme, calpain, was recruited, resulting in the breakdown of spine actin-interacting proteins including spectrin. Pharmacological approaches demonstrated that calpain recruitment contributed critically to CRH-induced spine loss. In conclusion, the stress hormone CRH co-opts mechanisms that contribute to the plasticity and integrity of excitatory synapses, leading to selective loss of dendritic spines. This spine loss might function as an adaptive mechanism preventing the consequences of adverse memories associated with severe stress. PMID:24155300

  12. NMDA Receptor Activation and Calpain Contribute to Disruption of Dendritic Spines by the Stress Neuropeptide CRH

    PubMed Central

    Andres, Adrienne L.; Regev, Limor; Phi, Lucas; Seese, Ronald R.; Chen, Yuncai; Gall, Christine M.

    2013-01-01

    The complex effects of stress on learning and memory are mediated, in part, by stress-induced changes in the composition and structure of excitatory synapses. In the hippocampus, the effects of stress involve several factors including glucocorticoids and the stress-released neuropeptide corticotropin-releasing hormone (CRH), which influence the integrity of dendritic spines and the structure and function of the excitatory synapses they carry. CRH, at nanomolar, presumed-stress levels, rapidly abolishes short-term synaptic plasticity and destroys dendritic spines, yet the mechanisms for these effects are not fully understood. Here we tested the hypothesis that glutamate receptor-mediated processes, which shape synaptic structure and function, are engaged by CRH and contribute to spine destabilization. In cultured rat hippocampal neurons, CRH application reduced dendritic spine density in a time- and dose-dependent manner, and this action depended on the CRH receptor type 1. CRH-mediated spine loss required network activity and the activation of NMDA, but not of AMPA receptors; indeed GluR1-containing dendritic spines were resistant to CRH. Downstream of NMDA receptors, the calcium-dependent enzyme, calpain, was recruited, resulting in the breakdown of spine actin-interacting proteins including spectrin. Pharmacological approaches demonstrated that calpain recruitment contributed critically to CRH-induced spine loss. In conclusion, the stress hormone CRH co-opts mechanisms that contribute to the plasticity and integrity of excitatory synapses, leading to selective loss of dendritic spines. This spine loss might function as an adaptive mechanism preventing the consequences of adverse memories associated with severe stress. PMID:24155300

  13. Social isolation-induced increase in NMDA receptors in the hippocampus exacerbates emotional dysregulation in mice.

    PubMed

    Chang, Chih-Hua; Hsiao, Ya-Hsin; Chen, Yu-Wen; Yu, Yang-Jung; Gean, Po-Wu

    2015-04-01

    Epidemiological studies have shown that early life adverse events have long-term effects on the susceptibility to subsequent stress exposure in adolescence, but the precise mechanism is unclear. In the present study, mice on postnatal day 21-28 were randomly assigned to either a group or isolated cages for 8 weeks. The socially isolated (SI) mice exhibited a higher level of spontaneous locomotor activity, a longer duration of immobility in the forced swimming test (FST), significantly less prepulse inhibition (PPI) and an increase in aggressive (but not attack) behavior. However, acute stress markedly exacerbated the attack counts of the SI mice but did not affect the group housing (GH) mice. SI mice exhibited higher synaptosomal NR2A and NR2B levels in the hippocampus as compared to the GH mice. Whole-cell patch clamp recordings of CA1 neurons in hippocampal slices showed that the SI mice exhibited a higher input-output relationship of NMDAR-EPSCs as compared to the GH mice. Application of the NR2B -specific antagonist ifenprodil produced a greater attenuating effect on NMDAR-EPSCs in slices from the SI mice. NMDAR EPSCs recorded from the SI mice had a slower deactivation kinetic. MK-801, CPP and ifenprodil, the NMDA antagonists, reversed acute stress-induced exaggeration of aggressive and depressive behaviors. Furthermore, acute stress-induced exacerbation of attack behavior in the SI mice was abolished after the knockdown of NR2B expression. These results suggest that social isolation-induced increased expression of NMDA receptors in the hippocampus involves stress exacerbation of aggressive behaviors. Amelioration of aggressive behaviors by NMDA antagonists may open a new avenue for the treatment of psychopathologies that involve outbursts of emotional aggression in neglected children. PMID:25348768

  14. Local NMDA Receptor Blockade Attenuates Chronic Tinnitus and Associated Brain Activity in an Animal Model

    PubMed Central

    Brozoski, Thomas J.; Wisner, Kurt W.; Odintsov, Boris; Bauer, Carol A.

    2013-01-01

    Chronic tinnitus has no broadly effective treatment. Identification of specific markers for tinnitus should facilitate the development of effective therapeutics. Recently it was shown that glutamatergic blockade in the cerebellar paraflocculus, using an antagonist cocktail was successful in reducing chronic tinnitus. The present experiment examined the effect of selective N-methyl d-aspartate (NMDA) receptor blockade on tinnitus and associated spontaneous brain activity in a rat model. The NMDA antagonist, D(−)-2-amino-5-phosphonopentanoic acid (D-AP5) (0.5 mM), was continuously infused for 2 weeks directly to the ipsilateral paraflocculus of rats with tinnitus induced months prior by unilateral noise exposure. Treated rats were compared to untreated normal controls without tinnitus, and to untreated positive controls with tinnitus. D-AP5 significantly decreased tinnitus within three days of beginning treatment, and continued to significantly reduce tinnitus throughout the course of treatment and for 23 days thereafter, at which time testing was halted. At the conclusion of psychophysical testing, neural activity was assessed using manganese enhanced magnetic resonance imaging (MEMRI). In agreement with previous research, untreated animals with chronic tinnitus showed significantly elevated bilateral activity in their paraflocculus and brainstem cochlear nuclei, but not in mid or forebrain structures. In contrast, D-AP5-treated-tinnitus animals showed significantly less bilateral parafloccular and dorsal cochlear nucleus activity, as well as significantly less contralateral ventral cochlear nucleus activity. It was concluded that NMDA-mediated glutamatergic transmission in the paraflocculus appears to be a necessary component of chronic noise-induced tinnitus in a rat model. Additionally, it was confirmed that in this model, elevated spontaneous activity in the cerebellar paraflocculus and auditory brainstem is associated with tinnitus. PMID:24282480

  15. Local NMDA receptor blockade attenuates chronic tinnitus and associated brain activity in an animal model.

    PubMed

    Brozoski, Thomas J; Wisner, Kurt W; Odintsov, Boris; Bauer, Carol A

    2013-01-01

    Chronic tinnitus has no broadly effective treatment. Identification of specific markers for tinnitus should facilitate the development of effective therapeutics. Recently it was shown that glutamatergic blockade in the cerebellar paraflocculus, using an antagonist cocktail was successful in reducing chronic tinnitus. The present experiment examined the effect of selective N-methyl d-aspartate (NMDA) receptor blockade on tinnitus and associated spontaneous brain activity in a rat model. The NMDA antagonist, D(-)-2-amino-5-phosphonopentanoic acid (D-AP5) (0.5 mM), was continuously infused for 2 weeks directly to the ipsilateral paraflocculus of rats with tinnitus induced months prior by unilateral noise exposure. Treated rats were compared to untreated normal controls without tinnitus, and to untreated positive controls with tinnitus. D-AP5 significantly decreased tinnitus within three days of beginning treatment, and continued to significantly reduce tinnitus throughout the course of treatment and for 23 days thereafter, at which time testing was halted. At the conclusion of psychophysical testing, neural activity was assessed using manganese enhanced magnetic resonance imaging (MEMRI). In agreement with previous research, untreated animals with chronic tinnitus showed significantly elevated bilateral activity in their paraflocculus and brainstem cochlear nuclei, but not in mid or forebrain structures. In contrast, D-AP5-treated-tinnitus animals showed significantly less bilateral parafloccular and dorsal cochlear nucleus activity, as well as significantly less contralateral ventral cochlear nucleus activity. It was concluded that NMDA-mediated glutamatergic transmission in the paraflocculus appears to be a necessary component of chronic noise-induced tinnitus in a rat model. Additionally, it was confirmed that in this model, elevated spontaneous activity in the cerebellar paraflocculus and auditory brainstem is associated with tinnitus. PMID:24282480

  16. Repeated Blockade of NMDA Receptors During Adolescence Impairs Reversal Learning and Disrupts GABAergic Interneurons in Rat Medial Prefrontal Cortex.

    PubMed

    Li, Ji-Tao; Su, Yun-Ai; Wang, Hong-Li; Zhao, Ying-Ying; Liao, Xue-Mei; Wang, Xiao-Dong; Si, Tian-Mei

    2016-01-01

    Adolescence is of particular significance to schizophrenia, since psychosis onset typically occurs in this critical period. Based on the N-methyl-D-aspartate (NMDA) receptor hypofunction hypothesis of schizophrenia, in this study, we investigated whether and how repeated NMDA receptor blockade during adolescence would affect GABAergic interneurons in rat medial prefrontal cortex (mPFC) and mPFC-mediated cognitive functions. Specifically, adolescent rats were subjected to intraperitoneal administration of MK-801 (0.1, 0.2, 0.4 mg/kg), a non-competitive NMDA receptor antagonist, for 14 days and then tested for reference memory and reversal learning in the water maze. The density of parvabumin (PV)-, calbindin (CB)- and calretinin (CR)-positive neurons in mPFC was analyzed at either 24 h or 7 days after drug cessation. We found that MK-801 treatment delayed reversal learning in the water maze without affecting initial acquisition. Strikingly, MK-801 treatment also significantly reduced the density of PV(+) and CB(+) neurons, and this effect persisted for 7 days after drug cessation at the dose of 0.2 mg/kg. We further demonstrated that the reduction in PV(+) and CB(+) neuron densities was ascribed to a downregulation of the expression levels of PV and CB, but not to neuronal death. These results parallel the behavioral and neuropathological changes of schizophrenia and provide evidence that adolescent NMDA receptors antagonism offers a useful tool for unraveling the etiology of the disease. PMID:26973457

  17. A novel form of long-term potentiation selectively expressed by NMDA receptors at hippocampal mossy fiber synapses

    PubMed Central

    Kwon, Hyung-Bae; Castillo, Pablo E.

    2008-01-01

    The mossy fiber to CA3 pyramidal cell synapse (mf-CA3) provides a major source of excitation to the hippocampus. Thus far, these glutamatergic synapses are well recognized for showing a presynaptic, NMDA receptor-independent form of LTP which is expressed as a long-lasting increase of transmitter release. Here, we show that in addition to this “classical” LTP, mf-CA3 synapses can undergo a form of LTP characterized by a selective enhancement of NMDA receptor-mediated transmission. This potentiation requires coactivation of NMDA and mGlu5 receptors, and a postsynaptic calcium rise. Unlike classical LTP, expression of this novel mossy fiber LTP is due to a PKC-dependent recruitment of NMDA receptors specifically to the mf-CA3 synapse via a SNARE-dependent process. Having two mechanistically different forms of LTP may allow mf-CA3 synapses to respond with more flexibility to the changing demands of the hippocampal network. PMID:18184568

  18. Magnetic resonance analysis of the effects of acute ammonia intoxication on rat brain. Role of NMDA receptors.

    PubMed

    Cauli, Omar; López-Larrubia, Pilar; Rodrigues, Tiago B; Cerdán, Sebastián; Felipo, Vicente

    2007-11-01

    Acute ammonia intoxication leads to rapid death, which is prevented by blocking N-methyl-d-aspartate (NMDA) receptors. The subsequent mechanisms leading to death remain unclear. Brain edema seems an important step. The aim of this work was to study the effects of acute ammonia intoxication on different cerebral parameters in vivo using magnetic resonance and to assess which effects are mediated by NMDA receptors activation. To assess edema induction, we injected rats with ammonium acetate and measured apparent diffusion coefficient (ADC) in 16 brain areas. We also analyzed the effects on T1, T2, and T2* maps and whether these effects are prevented by blocking NMDA receptors. The effects of acute ammonia intoxication are different in different brain areas. T1 relaxation time is reduced in eight areas. T2 relaxation time is reduced only in ventral thalamus and globus pallidus. ADC values increased in hippocampus, caudate-putamen, substantia nigra and cerebellar cortex, reflecting vasogenic edema. ADC decreased in hypothalamus, reflecting cytotoxic edema. Myo-inositol increased in cerebellum and substantia nigra, reflecting vasogenic edema. N-acetyl-aspartate decreased in cerebellum, reflecting neuronal damage. Changes in N-acetyl-aspartate, T1 and T2 are prevented by blocking NMDA receptors with MK-801 while changes in ADC or myo-inositol (induction of edema) are not. PMID:17727627

  19. Spatial Discrimination Reversal Learning in Weanling Rats Is Impaired by Striatal Administration of an NMDA-Receptor Antagonist

    ERIC Educational Resources Information Center

    Watson, Deborah J.; Stanton, Mark E.

    2009-01-01

    The striatum plays a major role in both motor control and learning and memory, including executive function and "behavioral flexibility." Lesion, temporary inactivation, and infusion of an N-methyl-d-aspartate (NMDA)-receptor antagonist into the dorsomedial striatum (dmSTR) impair reversal learning in adult rats. Systemic administration of MK-801…

  20. Repeated Blockade of NMDA Receptors During Adolescence Impairs Reversal Learning and Disrupts GABAergic Interneurons in Rat Medial Prefrontal Cortex

    PubMed Central

    Li, Ji-Tao; Su, Yun-Ai; Wang, Hong-Li; Zhao, Ying-Ying; Liao, Xue-Mei; Wang, Xiao-Dong; Si, Tian-Mei

    2016-01-01

    Adolescence is of particular significance to schizophrenia, since psychosis onset typically occurs in this critical period. Based on the N-methyl-D-aspartate (NMDA) receptor hypofunction hypothesis of schizophrenia, in this study, we investigated whether and how repeated NMDA receptor blockade during adolescence would affect GABAergic interneurons in rat medial prefrontal cortex (mPFC) and mPFC-mediated cognitive functions. Specifically, adolescent rats were subjected to intraperitoneal administration of MK-801 (0.1, 0.2, 0.4 mg/kg), a non-competitive NMDA receptor antagonist, for 14 days and then tested for reference memory and reversal learning in the water maze. The density of parvabumin (PV)-, calbindin (CB)- and calretinin (CR)-positive neurons in mPFC was analyzed at either 24 h or 7 days after drug cessation. We found that MK-801 treatment delayed reversal learning in the water maze without affecting initial acquisition. Strikingly, MK-801 treatment also significantly reduced the density of PV+ and CB+ neurons, and this effect persisted for 7 days after drug cessation at the dose of 0.2 mg/kg. We further demonstrated that the reduction in PV+ and CB+ neuron densities was ascribed to a downregulation of the expression levels of PV and CB, but not to neuronal death. These results parallel the behavioral and neuropathological changes of schizophrenia and provide evidence that adolescent NMDA receptors antagonism offers a useful tool for unraveling the etiology of the disease. PMID:26973457

  1. NMDA Receptor- and ERK-Dependent Histone Methylation Changes in the Lateral Amygdala Bidirectionally Regulate Fear Memory Formation

    ERIC Educational Resources Information Center

    Gupta-Agarwal, Swati; Jarome, Timothy J.; Fernandez, Jordan; Lubin, Farah D.

    2014-01-01

    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…

  2. Dissociation of extinction and behavioral disinhibition: the role of NMDA receptors in the pigeon associative forebrain during extinction.

    PubMed

    Lissek, Silke; Güntürkün, Onur

    2003-09-01

    Extinction is a unique learning process that requires the alteration of stimulus-response associations such that the organism ceases to respond to a previously rewarded stimulus. Extinction is mostly studied with fear conditioning and is impaired by lesions of the prefrontal cortex as well as by blockade of NMDA receptors in the amygdala. Because previous tasks could not clearly disambiguate extinction from behavioral disinhibition, the underlying process was difficult to define. In this study, we examined the possible role of NMDA receptors and the pigeon "prefrontal cortex," the neostriatum caudolaterale (NCL), for extinction of appetitive instrumental conditioning. We used a new design that discerns extinction from behavioral disinhibition. Our results demonstrate that NCL lesions cause deficits neither in extinction learning nor in extinction recall. However, blockade of NMDA receptors in the pigeon NCL by DL-AP-5 drastically impairs extinction learning without producing behavioral disinhibition or deficits in extinction recall. We suggest that NMDA receptors in the NCL contribute to the establishment of a learning process that selectively signals the change in value of the instrumental stimulus. Although NCL plays a key role for extinction learning, other structures can subsume similar functions after postlesional regeneration. PMID:12954874

  3. NR2A/B-containing NMDA receptors mediate cocaine-induced synaptic plasticity in the VTA and cocaine psychomotor sensitization.

    PubMed

    Schumann, Johanna; Matzner, Henry; Michaeli, Avner; Yaka, Rami

    2009-09-18

    Cocaine-induced modifications of glutamatergic synaptic transmission in the mesolimbic system play a key role in adaptations that promote addictive behaviors. In particular, the activation of ionotropic glutamate N-methyl-D-aspartate receptor (NMDAR) in the ventral tegmental area (VTA) is critical for both cocaine-induced synaptic plasticity induced by a single cocaine injection and for the initiation of cocaine psychomotor sensitization. In this study, we set to determine whether the NR2 subunits of the NMDAR play a specific role in triggering cocaine-induced alterations in synaptic plasticity and the development of psychomotor sensitization. We found that inhibition of NR2A-containing NMDARs by NVP-AAM077, or NR2B-containing receptors by ifenprodil, blocked cocaine-induced increase in the AMPAR/NMDAR currents ratio, a measure of long-term potentiation (LTP) in vivo, in VTA neurons 24h following a single cocaine injection. Furthermore, inhibition of the NR2A subunit during the development of psychomotor sensitization attenuated the enhanced locomotor activity following repeated cocaine injections. Together, these results suggest that NR2-containing NMDA receptors play an important role in the machinery that triggers synaptic and behavioral adaptations to drugs of abuse such as cocaine. PMID:19524640

  4. S-nitrosylated SHP-2 contributes to NMDA receptor-mediated excitotoxicity in acute ischemic stroke

    PubMed Central

    Shi, Zhong-Qing; Sunico, Carmen R.; McKercher, Scott R.; Cui, Jiankun; Feng, Gen-Sheng; Nakamura, Tomohiro; Lipton, Stuart A.

    2013-01-01

    Overproduction of nitric oxide (NO) can cause neuronal damage, contributing to the pathogenesis of several neurodegenerative diseases and stroke (i.e., focal cerebral ischemia). NO can mediate neurotoxic effects at least in part via protein S-nitrosylation, a reaction that covalently attaches NO to a cysteine thiol (or thiolate anion) to form an S-nitrosothiol. Recently, the tyrosine phosphatase Src homology region 2-containing protein tyrosine phosphatase-2 (SHP-2) and its downstream pathways have emerged as important mediators of cell survival. Here we report that in neurons and brain tissue NO can S-nitrosylate SHP-2 at its active site cysteine, forming S-nitrosylated SHP-2 (SNO–SHP-2). We found that NMDA exposure in vitro and transient focal cerebral ischemia in vivo resulted in increased levels of SNO–SHP-2. S-Nitrosylation of SHP-2 inhibited its phosphatase activity, blocking downstream activation of the neuroprotective physiological ERK1/2 pathway, thus increasing susceptibility to NMDA receptor-mediated excitotoxicity. These findings suggest that formation of SNO–SHP-2 represents a key chemical reaction contributing to excitotoxic damage in stroke and potentially other neurological disorders. PMID:23382182

  5. Intracellular Ca2+ stores modulate SOCCs and NMDA receptors via tyrosine kinases in rat hippocampal neurons.

    PubMed

    Koss, David J; Riedel, Gernot; Platt, Bettina

    2009-07-01

    The regulation of intracellular Ca(2+) signalling by phosphorylation processes remains poorly defined, particularly with regards to tyrosine phosphorylation. Evidence from non-excitable cells implicates tyrosine phosphorylation in the activation of so-called store-operated Ca(2+) channels (SOCCs), but their involvement in neuronal Ca(2+) signalling is still elusive. In the present study, we determined the role of protein tyrosine kinases (PTKs) and tyrosine phosphatases (PTPs) in the coupling between intracellular Ca(2+) stores and SOCCs in neonatal rat hippocampal neurons by Fura-2 Ca(2+) imaging. An early Ca(2+) response from intracellular stores was triggered with thapsigargin, and followed by a secondary plasma membrane Ca(2+) response. This phase was blocked by the non-specific Ca(2+) channel blocker NiCl and the SOCC blocker, 2-aminoethoxydiphenyl borate (2-APB). Interestingly, two structurally distinct PTK inhibitors, genistein and AG126, also inhibited this secondary response. Application of the PTP inhibitor sodium orthovanadate (OV) also activated a sustained and tyrosine kinase dependent Ca(2+) response, blocked by NiCl and 2-APB. In addition, OV resulted in a Ca(2+) store dependent enhancement of NMDA responses, corresponding to, and occluding the signalling pathway for group I metabotropic glutamate receptors (mGluRs). This study provides first evidence for tyrosine based phospho-regulation of SOCCs and NMDA signalling in neurons. PMID:19423160

  6. Tetramethylenedisulfotetramine Alters Ca2+ Dynamics in Cultured Hippocampal Neurons: Mitigation by NMDA Receptor Blockade and GABAA Receptor-Positive Modulation

    PubMed Central

    Pessah, Isaac N.

    2012-01-01

    Tetramethylenedisulfotetramine (TETS) is a potent convulsant that is considered a chemical threat agent. We characterized TETS as an activator of spontaneous Ca2+ oscillations and electrical burst discharges in mouse hippocampal neuronal cultures at 13–17 days in vitro using FLIPR Fluo-4 fluorescence measurements and extracellular microelectrode array recording. Acute exposure to TETS (≥ 2µM) reversibly altered the pattern of spontaneous neuronal discharges, producing clustered burst firing and an overall increase in discharge frequency. TETS also dramatically affected Ca2+ dynamics causing an immediate but transient elevation of neuronal intracellular Ca2+ followed by decreased frequency of Ca2+ oscillations but greater peak amplitude. The effect on Ca2+ dynamics was similar to that elicited by picrotoxin and bicuculline, supporting the view that TETS acts by inhibiting type A gamma-aminobutyric acid (GABAA) receptor function. The effect of TETS on Ca2+ dynamics requires activation of N-methyl-d-aspartic acid (NMDA) receptors, because the changes induced by TETS were prevented by MK-801 block of NMDA receptors, but not nifedipine block of L-type Ca2+ channels. Pretreatment with the GABAA receptor-positive modulators diazepam and allopregnanolone partially mitigated TETS-induced changes in Ca2+ dynamics. Moreover, low, minimally effective concentrations of diazepam (0.1µM) and allopregnanolone (0.1µM), when administered together, were highly effective in suppressing TETS-induced alterations in Ca2+ dynamics, suggesting that the combination of positive modulators of synaptic and extrasynaptic GABAA receptors may have therapeutic potential. These rapid throughput in vitro assays may assist in the identification of single agents or combinations that have utility in the treatment of TETS intoxication. PMID:22889812

  7. Retrieval-induced NMDA receptor-dependent Arc expression in two models of cocaine-cue memory.

    PubMed

    Alaghband, Yasaman; O'Dell, Steven J; Azarnia, Siavash; Khalaj, Anna J; Guzowski, John F; Marshall, John F

    2014-12-01

    The association of environmental cues with drugs of abuse results in persistent drug-cue memories. These memories contribute significantly to relapse among addicts. While conditioned place preference (CPP) is a well-established paradigm frequently used to examine the modulation of drug-cue memories, very few studies have used the non-preference-based model conditioned activity (CA) for this purpose. Here, we used both experimental approaches to investigate the neural substrates of cocaine-cue memories. First, we directly compared, in a consistent setting, the involvement of cortical and subcortical brain regions in cocaine-cue memory retrieval by quantifying activity-regulated cytoskeletal-associated (Arc) protein expression in both the CPP and CA models. Second, because NMDA receptor activation is required for Arc expression, we investigated the NMDA receptor dependency of memory persistence using the CA model. In both the CPP and CA models, drug-paired animals showed significant increases in Arc immunoreactivity in regions of the frontal cortex and amygdala compared to unpaired controls. Additionally, administration of a NMDA receptor antagonist (MK-801 or memantine) immediately after cocaine-CA memory reactivation impaired the subsequent conditioned locomotion associated with the cocaine-paired environment. The enhanced Arc expression evident in a subset of corticolimbic regions after retrieval of a cocaine-context memory, observed in both the CPP and CA paradigms, likely signifies that these regions: (i) are activated during retrieval of these memories irrespective of preference-based decisions, and (ii) undergo neuroplasticity in order to update information about cues previously associated with cocaine. This study also establishes the involvement of NMDA receptors in maintaining memories established using the CA model, a characteristic previously demonstrated using CPP. Overall, these results demonstrate the utility of the CA model for studies of cocaine

  8. Serotonergic modulation of muscle acetylcholine receptors of different subunit composition.

    PubMed Central

    García-Colunga, J; Miledi, R

    1996-01-01

    Modulation of muscle acetylcholine (AcCho) receptors (AcChoRs) by serotonin [5-hydroxytryptamine (5HT)] and other serotonergic compounds was studied in Xenopus laevis oocytes. Various combinations of alpha, beta, gamma, and delta subunit RNAs were injected into oocytes, and membrane currents elicited by AcCho were recorded under voltage clamp. Judging by the amplitudes of AcCho currents generated, the levels of functional receptor expression were: alpha beta gamma delta > alpha beta delta > alpha beta gamma > alpha gamma delta. The alpha beta gamma delta and alpha beta delta AcChoR Subtypes were strongly blocked by 5HT, whereas the alpha beta gamma receptor was blocked only slightly. The order of blocking potency of AcChoRs by 5HT was: alpha beta delta > alpha beta gamma delta > alpha beta gamma. 5HT receptor antagonists, such as methysergide and spiperone, were even more potent blockers of AcChoRs than 5HT but did not show much subunit selectivity. Blockage of alpha beta gamma delta and alpha beta delta receptors by 5HT was voltage-dependent, and the voltage dependence was abolished when the delta subunit was omitted. These findings may need to be taken into consideration when trying to elucidate the mode of action of many clinically important serotonergic compounds. Images Fig. 3 PMID:8633003

  9. Metabotropic glutamate receptor signaling is required for NMDA receptor-dependent ocular dominance plasticity and LTD in visual cortex

    PubMed Central

    Sidorov, Michael S.; Kaplan, Eitan S.; Osterweil, Emily K.; Lindemann, Lothar; Bear, Mark F.

    2015-01-01

    A feature of early postnatal neocortical development is a transient peak in signaling via metabotropic glutamate receptor 5 (mGluR5). In visual cortex, this change coincides with increased sensitivity of excitatory synapses to monocular deprivation (MD). However, loss of visual responsiveness after MD occurs via mechanisms revealed by the study of long-term depression (LTD) of synaptic transmission, which in layer 4 is induced by acute activation of NMDA receptors (NMDARs) rather than mGluR5. Here we report that chronic postnatal down-regulation of mGluR5 signaling produces coordinated impairments in both NMDAR-dependent LTD in vitro and ocular dominance plasticity in vivo. The data suggest that ongoing mGluR5 signaling during a critical period of postnatal development establishes the biochemical conditions that are permissive for activity-dependent sculpting of excitatory synapses via the mechanism of NMDAR-dependent LTD. PMID:26417096

  10. All quiet on the neuronal front: NMDA receptor inhibition by prion protein.

    PubMed

    Steele, Andrew D

    2008-06-01

    The normal function of the prion protein (PrP)--the causative agent of mad cow or prion disease--has long remained out of reach. Deciphering PrP's function may help to unravel the complex chain of events triggered by PrP misfolding during prion disease. In this issue of the JCB, an exciting paper (Khosravani, H., Y. Zhang, S. Tsutsui, S. Hameed, C. Altier, J. Hamid, L. Chen, M. Villemaire, Z. Ali, F.R. Jirik, and G.W. Zamponi. 2008. J. Cell Biol. 181:551-565) connects diverse observations regarding PrP into a coherent framework whereby PrP dampens the activity of an N-methyl-D-aspartate (NMDA) receptor (NMDAR) subtype and reduces excitotoxic lesions. The findings of this study suggest that understanding the normal function of proteins associated with neurodegenerative disease may elucidate the molecular pathogenesis. PMID:18504309

  11. All quiet on the neuronal front: NMDA receptor inhibition by prion protein.

    PubMed

    Steele, Andrew D

    2008-05-01

    The normal function of the prion protein (PrP)-the causative agent of mad cow or prion disease-has long remained out of reach. Deciphering PrP's function may help to unravel the complex chain of events triggered by PrP misfolding during prion disease. In this issue of the JCB, an exciting paper (Khosravani, H., Y. Zhang, S. Tsutsui, S. Hameed, C. Altier, J. Hamid, L. Chen, M. Villemaire, Z. Ali, F.R. Jirik, and G.W. Zamponi. 2008. J. Cell Biol. 181:551-565) connects diverse observations regarding PrP into a coherent framework whereby PrP dampens the activity of an N-methyl-d-aspartate (NMDA) receptor (NMDAR) subtype and reduces excitotoxic lesions. The findings of this study suggest that understanding the normal function of proteins associated with neurodegenerative disease may elucidate the molecular pathogenesis. PMID:18443224

  12. Essential role of postsynaptic NMDA receptors in developmental refinement of excitatory synapses.

    PubMed

    Zhang, Zhong-wei; Peterson, Matthew; Liu, Hong

    2013-01-15

    Neurons in the brains of newborns are usually connected with many other neurons through weak synapses. This early pattern of connectivity is refined through pruning of many immature connections and strengthening of the remaining ones. NMDA receptors (NMDARs) are essential for the development of excitatory synapses, but their role in synaptic refinement is controversial. Although chronic application of blockers or global knockdown of NMDARs disrupts developmental refinement in many parts of the brain, the ubiquitous presence of NMDARs makes it difficult to dissociate direct effects from indirect ones. We addressed this question in the thalamus by using genetic mosaic deletion of NMDARs. We demonstrate that pruning and strengthening of immature synapses are blocked in neurons without NMDARs, but occur normally in neighboring neurons with NMDARs. Our data support a model in which activation of NMDARs in postsynaptic neurons initiates synaptic refinement. PMID:23277569

  13. Essential role of postsynaptic NMDA receptors in developmental refinement of excitatory synapses

    PubMed Central

    Zhang, Zhong-wei; Peterson, Matthew; Liu, Hong

    2013-01-01

    Neurons in the brains of newborns are usually connected with many other neurons through weak synapses. This early pattern of connectivity is refined through pruning of many immature connections and strengthening of the remaining ones. NMDA receptors (NMDARs) are essential for the development of excitatory synapses, but their role in synaptic refinement is controversial. Although chronic application of blockers or global knockdown of NMDARs disrupts developmental refinement in many parts of the brain, the ubiquitous presence of NMDARs makes it difficult to dissociate direct effects from indirect ones. We addressed this question in the thalamus by using genetic mosaic deletion of NMDARs. We demonstrate that pruning and strengthening of immature synapses are blocked in neurons without NMDARs, but occur normally in neighboring neurons with NMDARs. Our data support a model in which activation of NMDARs in postsynaptic neurons initiates synaptic refinement. PMID:23277569

  14. NMDA Receptors Multiplicatively Scale Visual Signals and Enhance Directional Motion Discrimination in Retinal Ganglion Cells.

    PubMed

    Poleg-Polsky, Alon; Diamond, Jeffrey S

    2016-03-16

    Postsynaptic responses in many CNS neurons are typically small and variable, often making it difficult to distinguish physiologically relevant signals from background noise. To extract salient information, neurons are thought to integrate multiple synaptic inputs and/or selectively amplify specific synaptic activation patterns. Here, we present evidence for a third strategy: directionally selective ganglion cells (DSGCs) in the mouse retina multiplicatively scale visual signals via a mechanism that requires both nonlinear NMDA receptor (NMDAR) conductances in DSGC dendrites and directionally tuned inhibition provided by the upstream retinal circuitry. Postsynaptic multiplication enables DSGCs to discriminate visual motion more accurately in noisy visual conditions without compromising directional tuning. These findings demonstrate a novel role for NMDARs in synaptic processing and provide new insights into how synaptic and network features interact to accomplish physiologically relevant neural computations. PMID:26948896

  15. In vitro and in vivo evaluation of polymethylene tetraamine derivatives as NMDA receptor channel blockers.

    PubMed

    Saiki, Ryotaro; Yoshizawa, Yuki; Minarini, Anna; Milelli, Andrea; Marchetti, Chiara; Tumiatti, Vincenzo; Toida, Toshihiko; Kashiwagi, Keiko; Igarashi, Kazuei

    2013-07-01

    The biological activities of six symmetrically substituted 2-methoxy-benzyl polymethylene tetraamines (1-4) and diphenylethyl polymethylene tetraamines (5 and 6) as N-methyl-D-aspartate (NMDA) receptor channel blockers, were evaluated in vitro and in vivo. Although all compounds exhibited stronger channel block activities in comparison to memantine in Xenopus oocytes voltage clamped at -70 mV, only compound 2 (0.4 mg/kg intravenous injection) decreased the size of brain infarction in a photochemically induced thrombosis model mice at the same extent of memantine (10mg/kg intravenous injection). Other compounds (1, 3, 4, 5 and 6) did not decrease the size of brain infarction significantly due to the limited injection doses. The present study suggests that compound 2 could represent a valuable lead compound to design low toxicity polyamines for clinical use against stroke. PMID:23692871

  16. Conformational signaling required for synaptic plasticity by the NMDA receptor complex.

    PubMed

    Aow, Jonathan; Dore, Kim; Malinow, Roberto

    2015-11-24

    The NMDA receptor (NMDAR) is known to transmit important information by conducting calcium ions. However, some recent studies suggest that activation of NMDARs can trigger synaptic plasticity in the absence of ion flow. Does ligand binding transmit information to signaling molecules that