Sample records for n-methyl-d-aspartate nmda glutamate

  1. Implication of Genes for the N-Methyl-D-Aspartate (NMDA) Receptor in Substance Addictions.

    PubMed

    Chen, Jiali; Ma, Yunlong; Fan, Rongli; Yang, Zhongli; Li, Ming D

    2018-02-10

    Drug dependence is a chronic brain disease with harmful consequences for both individual users and society. Glutamate is a primary excitatory neurotransmitter in the brain, and both in vivo and in vitro experiments have implicated N-methyl-D-aspartate (NMDA) receptor, a glutamate receptor, as an element in various types of addiction. Recent findings from genetics-based approaches such as genome-wide linkage, candidate gene association, genome-wide association (GWA), and next-generation sequencing have demonstrated the significant association of NMDA receptor subunit genes such as GluN3A, GluN2B, and GluN2A with various addiction-related phenotypes. Of these genes, GluN3A has been the most studied, and it has been revealed to play crucial roles in the etiology of addictions. In this communication, we provide an updated view of the genetic effects of NMDA receptor subunit genes and their functions in the etiology of addictions based on the findings from investigation of both common and rare variants as well as SNP-SNP interactions. To better understand the molecular mechanisms underlying addiction-related behaviors and to promote the development of specific medicines for the prevention and treatment of addictions, current efforts aim not only to identify more causal variants in NMDA receptor subunits by using large independent samples but also to reveal the molecular functions of these variants in addictions.

  2. N-Methyl-d-aspartate Modulation of Nucleus Accumbens Dopamine Release by Metabotropic Glutamate Receptors: Fast Cyclic Voltammetry Studies in Rat Brain Slices in Vitro.

    PubMed

    Yavas, Ersin; Young, Andrew M J

    2017-02-15

    The N-methyl-d-aspartate (NMDA) receptor antagonist, phencyclidine, induces behavioral changes in rodents mimicking symptoms of schizophrenia, possibly mediated through dysregulation of glutamatergic control of mesolimbic dopamine release. We tested the hypothesis that NMDA receptor activation modulates accumbens dopamine release, and that phencyclidine pretreatment altered this modulation. NMDA caused a receptor-specific, dose-dependent decrease in electrically stimulated dopamine release in nucleus accumbens brain slices. This decrease was unaffected by picrotoxin, making it unlikely to be mediated through GABAergic neurones, but was decreased by the metabotropic glutamate receptor antagonist, (RS)-α-methyl-4-sulfonophenylglycine, indicating that NMDA activates mechanisms controlled by these receptors to decrease stimulated dopamine release. The effect of NMDA was unchanged by in vivo pretreatment with phencyclidine (twice daily for 5 days), with a washout period of at least 7 days before experimentation, which supports the hypothesis that there is no enduring direct effect of PCP at NMDA receptors after this pretreatment procedure. We propose that NMDA depression of accumbal dopamine release is mediated by metabotropic glutamate receptors located pre- or perisynaptically, and suggest that NMDA evoked increased extrasynaptic spillover of glutamate is sufficient to activate these receptors that, in turn, inhibit dopamine release. Furthermore, we suggest that enduring functional changes brought about by subchronic phencyclidine pretreatment, modeling deficits in schizophrenia, are downstream effects consequent on chronic blockade of NMDA receptors, rather than direct effects on NMDA receptors themselves.

  3. Ibogaine attenuation of morphine withdrawal in mice: role of glutamate N-methyl-D-aspartate receptors.

    PubMed

    Leal, Mirna Bainy; Michelin, Kátia; Souza, Diogo Onofre; Elisabetsky, Elaine

    2003-08-01

    Ibogaine (IBO) is an alkaloid with putative antiaddictive properties, alleviating opiates dependence and withdrawal. The glutamate N-methyl-D-aspartate (NMDA) receptors have been implicated in the physiological basis of drug addiction; accordingly, IBO acts as a noncompetitive NMDA antagonist. The purpose of this study was to evaluate the effects of IBO on naloxone-induced withdrawal syndrome in morphine-dependent mice, focusing on the role of NMDA receptors. Jumping, a major behavioral expression of such withdrawal, was significantly (P<.01) inhibited by IBO (40 and 80 mg/kg, 64.2% and 96.9% inhibition, respectively) and MK-801 (0.15 and 0.30 mg/kg, 67.3% and 97.7%, respectively) given prior to naloxone. Coadministration of the lower doses of IBO (40 mg/kg) and MK-801 (0.15 mg/kg) results in 94.7% inhibition of jumping, comparable to the effects of higher doses of either IBO or MK-801. IBO and MK-801 also significantly inhibited NMDA-induced (99.0% and 71.0%, respectively) jumping when given 30 min (but not 24 h) prior to NMDA in nonaddictive mice. There were no significant differences in [3H]MK-801 binding to cortical membranes from naive animals, morphine-dependent animals, or morphine-dependent animals treated with IBO or MK-801. This study provides further evidence that IBO does have an inhibitory effect on opiate withdrawal symptoms and suggests that the complex process resulting in morphine withdrawal includes an IBO-sensitive functional and transitory alteration of NMDA receptor.

  4. Opiate physical dependence and N-methyl-D-aspartate receptors.

    PubMed

    Noda, Yukihiro; Nabeshima, Toshitaka

    2004-10-01

    The present review focused the involvement of N-methyl-D-aspartate (NMDA) receptors in morphine physical dependence. The increased levels of extracellular glutamate, NMDA receptor zeta subunit (NR1) mRNA, NMDA receptor epsilon 1 subunit (NR2A) protein, phosphorylated Ca(2+)/calmodulin kinase II (p-CaMKII) protein, c-fos mRNA, c-Fos protein, are observed in the specific brain areas of mice and/or rats showing signs of naloxone-precipitated withdrawal. In preclinical and clinical studies, a variety of NMDA receptor antagonists and pretreatment with an antisense oligonucleotide of the NR1 have been reported to inhibit the development, expression and/or maintenance of opiate physical dependence. In contrast to data obtained in adult animals, NMDA receptor antagonists are neither effective in blocking the development of opiate dependence nor the expression of opiate withdrawal in neonatal rats. In the NMDA receptor-deficient mice, the NR2A knockout mice show the marked loss of typical withdrawal abstinence behaviors precipitated by naloxone. The rescue of NR2A protein by electroporation into the nucleus accumbens of NR2A knockout mice reverses the loss of abstinence behaviors. The activation of CaMKII and increased expression of c-Fos protein in the brain of animals with naloxone-precipitated withdrawal syndrome are prevented by NMDA receptor antagonists, whereas the increased levels of extracellular glutamate are not prevented by them. These findings indicate that glutamatergic neurotransmission at the NMDA receptor site contributes to the development, expression and maintenance of opiate dependence, and suggest that NMDA receptor antagonists may be a useful adjunct in the treatment of opiate dependence.

  5. Study of the n-methyl-d-aspartate antagonistic properties of anticholinergic drugs

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    McDonough, J.H.; Shih, T.M.

    1995-12-31

    A study of the N-methyl-D-aspartate antagonistic properties of anticholinergic drugs. PHARMACOL BIOCHEM BEHAV. 51(2/3) 249-253, 1995. Drugs that act at the N-methyl-D-aspartate (NMDA) receptor complex have the ability to terminate nerve agent-induced seizures and modulate the neuropathologic consequences of agent exposure. Drugs with mixed anticholinergic and anti-NMDA properties potentially provide an ideal class of compounds for development as anticonvulsant treatments for nerve agent casualties. The present experiment evaluated the potential NMDA antagonist activity of 11 anticholinergic drugs by determining whether pretreatment with the compound was capable of protecting mice from the lethal effects of NMDA. The following anticholinergic drugs antagonizedmore » NMDA lethality and are ranked according to their potency: mecamylamine > procyclidine = benactyzine > biperiden > tribexyphenidyl. The anticholinergics atropine, aprophen, azaprophen, benztropine, 3-quinudidinyl benzilate (QNB), and scopolamine failed to show NMDA antagonist properties. In addition, and unexpectedly, diazepam, ethanol, and pentobarbital were also shown to be capable of antagonizing NMDA lethality over a certain range of doses. The advantages and limitations of using antagonism of NMDA lethality in mice as a bioassay for determining the NMDA antagonist properties of drugs are also discussed.« less

  6. Ligand-specific Deactivation Time Course of GluN1/GluN2D NMDA Receptors

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    K Vance; N Simorowski; S Traynelis

    2011-12-31

    N-methyl-D-aspartate (NMDA) receptors belong to the family of ionotropic glutamate receptors that mediate a majority of excitatory synaptic transmission. One unique property of GluN1/GluN2D NMDA receptors is an unusually prolonged deactivation time course following the removal of L-glutamate. Here we show, using x-ray crystallography and electrophysiology, that the deactivation time course of GluN1/GluN2D receptors is influenced by the conformational variability of the ligand-binding domain (LBD) as well as the structure of the activating ligand. L-glutamate and L-CCG-IV induce significantly slower deactivation time courses compared with other agonists. Crystal structures of the isolated GluN2D LBD in complex with various ligands revealmore » that the binding of L-glutamate induces a unique conformation at the backside of the ligand-binding site in proximity to the region at which the transmembrane domain would be located in the intact receptors. These data suggest that the activity of the GluN1/GluN2D NMDA receptor is controlled distinctively by the endogenous neurotransmitter L-glutamate.« less

  7. N-Methyl-D-Aspartate Receptor Activation May Contribute to Glufosinate Neurotoxicity

    EPA Science Inventory

    N-Methyl-D-aspartate Receptor Activation May Contribute to Glufosinate Neurotoxicity Glufosinate (GLF) at high levels in mammals causes convulsions through a mechanism that is not completely understood. The structural similarity of GLF to glutamate (GLU) implicates the glutamate...

  8. Developmental regulation of N-methyl-D-aspartate- and kainate-type glutamate receptor expression in the rat spinal cord

    NASA Technical Reports Server (NTRS)

    Stegenga, S. L.; Kalb, R. G.

    2001-01-01

    Spinal motor neurons undergo experience-dependent development during a critical period in early postnatal life. It has been suggested that the repertoire of glutamate receptor subunits differs between young and mature motor neurons and contributes to this activity-dependent development. In the present study we examined the expression patterns of N-methyl-D-aspartate- and kainate-type glutamate receptor subunits during the postnatal maturation of the spinal cord. Young motor neurons express much higher levels of the N-methyl-D-aspartate receptor subunit NR1 than do adult motor neurons. Although there are eight potential splice variants of NR1, only a subgroup is expressed by motor neurons. With respect to NR2 receptor subunits, young motor neurons express NR2A and C, while adult motor neurons express only NR2A. Young motor neurons express kainate receptor subunits GluR5, 6 and KA2 but we are unable to detect these or any other kainate receptor subunits in the adult spinal cord. Other spinal cord regions display a distinct pattern of developmental regulation of N-methyl-D-aspartate and kainate receptor subunit expression in comparison to motor neurons. Our findings indicate a precise spatio-temporal regulation of individual subunit expression in the developing spinal cord. Specific combinations of subunits in developing neurons influence their excitable properties and could participate in the emergence of adult neuronal form and function.

  9. Characterization of N-methyl-D-aspartate-evoked taurine release in the developing and adult mouse hippocampus.

    PubMed

    Saransaari, P; Oja, S S

    2003-01-01

    Taurine is an inhibitory amino acid acting as an osmoregulator and neuroromodulator in the brain, with neuroprotective properties. The ionotropic glutamate receptor agonist N-methyl-D-aspartate (NMDA) greatly potentiates taurine release from brain preparations in both normal and ischemic conditions, the effect being particularly marked in the developing hippocampus. We now characterized the regulation of NMDA-stimulated taurine release from hippocampal slices from adult (3-month-old) and developing (7-day-old) mouse using a superfusion system. The NMDA-stimulated taurine release was receptor-mediated in both adult and developing mouse hippocampus. In adults, only NO-generating compounds, sodium nitroprusside, S-nitroso-N-acetylpenicillamine and hydroxylamine reduced the release, as did also NO synthase inhibitors, 7-nitroindazole and nitroarginine, indicating that the release is mediated by the NO/cGMP pathway. On the other hand, the regulation of the NMDA-evoked taurine release proved to be somewhat complex in the immature hippocampus. It was not affected by the NOergic compounds, but enhanced by the protein kinase C activator 4 beta-phorbol 12-myristate 13-acetate and adenosine receptor A(1) agonists, N(6)-cyclohexyladenosine and R(-)N(6)-(2-phenylisopropyl)adenosine in a receptor-mediated manner. The activation of both ionotropic 2-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptors and metabotropic glutamate group I receptors also enhanced the evoked release. The NMDA-receptor-stimulated taurine release could be a part of the neuroprotective properties of taurine, being important particularly under cell-damaging conditions in the developing hippocampus and hence preventing excitotoxicity.

  10. Ethanol Inhibition of Constitutively Open N-Methyl-d-Aspartate Receptors

    PubMed Central

    Xu, Minfu; Smothers, C. Thetford; Trudell, James

    2012-01-01

    N-Methyl-d-aspartate (NMDA) receptors gate a slow and calcium-rich component of the postsynaptic glutamate response. Like all ionotropic glutamate receptors, NMDA subunits contain a highly conserved motif (SYTANLAAF) in the transmembrane (TM) 3 domain that is critically involved in channel gating. Mutation of an alanine in this domain (A7; underlined above) results in constitutively open receptors that show reduced sensitivity to several allosteric modulators. In this study, we examined the effects of ethanol, a substance that inhibits NMDA currents via an unknown mechanism, on tonically active NMDA receptors expressed in human embryonic kidney 293 cells. Ethanol (100 mM) inhibited currents from GluN1(A7R)/GluN2A and GluN1(A7R)/GluN2B receptors by approximately 50%, whereas those from GluN1/GluN2B(A7R) receptors were reduced by less than 10%. In cysteine-substituted GluN1 and GluN2 A7 mutants, estimated ethanol IC50 values for agonist-gated currents were 101, 117, 103, and 69 mM for GluN1(A7C)/GluN2A, GluN1(A7C)/GluN2B, GluN1/GluN2A(A7C), and GluN1/GluN2B(A7C) receptors, respectively. After exposure to the thiol-modifying reagent 2-(trimethylammonium)ethyl methanethiosulfonate (MTSET), A7C mutants showed robust agonist-independent currents and reduced sensitivity to ethanol (IC50 values of 371, 256, 715, and 958 mM, respectively, as above). In contrast, cysteine modification of the ligand-binding domain resulted in constitutively open receptors that showed robust ethanol inhibition. Ethanol inhibition of MTSET-treated GluN1(A7C) receptors was further reduced by TM3/TM4 mutations previously shown to reduce ethanol sensitivity of agonist-gated receptors. Overall, these results show that ethanol affects NMDA receptor function at a site distal from agonist binding and appears to exert greater effects via perturbation of GluN2 subunits. PMID:22005043

  11. Identification of N-methyl-D-aspartic acid (NMDA) receptor subtype-specific binding sites that mediate direct interactions with scaffold protein PSD-95.

    PubMed

    Cousins, Sarah L; Stephenson, F Anne

    2012-04-13

    N-methyl-D-aspartate (NMDA) neurotransmitter receptors and the postsynaptic density-95 (PSD-95) membrane-associated guanylate kinase (MAGUK) family of scaffolding proteins are integral components of post-synaptic macromolecular signaling complexes that serve to propagate glutamate responses intracellularly. Classically, NMDA receptor NR2 subunits associate with PSD-95 MAGUKs via a conserved ES(E/D)V amino acid sequence located at their C termini. We previously challenged this dogma to demonstrate a second non-ES(E/D)V PSD-95-binding site in both NMDA receptor NR2A and NR2B subunits. Here, using a combination of co-immunoprecipitations from transfected mammalian cells, yeast two-hybrid interaction assays, and glutathione S-transferase (GST) pulldown assays, we show that NR2A subunits interact directly with PSD-95 via the C-terminal ESDV motif and additionally via an Src homology 3 domain-binding motif that associates with the Src homology 3 domain of PSD-95. Peptide inhibition of co-immunoprecipitations of NR2A and PSD-95 demonstrates that both the ESDV and non-ESDV sites are required for association in native brain tissue. Furthermore, we refine the non-ESDV site within NR2B to residues 1149-1157. These findings provide a molecular basis for the differential association of NMDA receptor subtypes with PSD-95 MAGUK scaffold proteins. These selective interactions may contribute to the organization, lateral mobility, and ultimately the function of NMDA receptor subtypes at synapses. Furthermore, they provide a more general molecular mechanism by which the scaffold, PSD-95, may discriminate between potential interacting partner proteins.

  12. Evidence for spinal N-methyl-d-aspartate receptor involvement in prolonged chemical nociception in the rat.

    PubMed

    Haley, Jane E; Dickenson, Anthony H

    2016-08-15

    We used in vivo electrophysiology and a model of more persistent nociceptive inputs to monitor spinal cord neuronal activity in anaesthetised rats to reveal the pharmacology of enhanced pain signalling. The study showed that all responses were blocked by non-selective antagonism of glutamate receptors but a selective and preferential role of the N-methyl-d-aspartate (NMDA) receptor in the prolonged plastic responses was clearly seen. The work lead to many publications, initially preclinical but increasingly from patient studies, showing the importance of the NMDA receptor in central sensitisation within the spinal cord and how this could relate to persistent pain states. This article is part of a Special Issue entitled SI:50th Anniversary Issue. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Heteroreceptor Complexes Formed by Dopamine D1, Histamine H3, and N-Methyl-D-Aspartate Glutamate Receptors as Targets to Prevent Neuronal Death in Alzheimer's Disease.

    PubMed

    Rodríguez-Ruiz, Mar; Moreno, Estefanía; Moreno-Delgado, David; Navarro, Gemma; Mallol, Josefa; Cortés, Antonio; Lluís, Carme; Canela, Enric I; Casadó, Vicent; McCormick, Peter J; Franco, Rafael

    2017-08-01

    Alzheimer's disease (AD) is a neurodegenerative disorder causing progressive memory loss and cognitive dysfunction. Anti-AD strategies targeting cell receptors consider them as isolated units. However, many cell surface receptors cooperate and physically contact each other forming complexes having different biochemical properties than individual receptors. We here report the discovery of dopamine D 1 , histamine H 3 , and N-methyl-D-aspartate (NMDA) glutamate receptor heteromers in heterologous systems and in rodent brain cortex. Heteromers were detected by co-immunoprecipitation and in situ proximity ligation assays (PLA) in the rat cortex where H 3 receptor agonists, via negative cross-talk, and H 3 receptor antagonists, via cross-antagonism, decreased D 1 receptor agonist signaling determined by ERK1/2 or Akt phosphorylation, and counteracted D 1 receptor-mediated excitotoxic cell death. Both D 1 and H 3 receptor antagonists also counteracted NMDA toxicity suggesting a complex interaction between NMDA receptors and D 1 -H 3 receptor heteromer function. Likely due to heteromerization, H 3 receptors act as allosteric regulator for D 1 and NMDA receptors. By bioluminescence resonance energy transfer (BRET), we demonstrated that D 1 or H 3 receptors form heteromers with NR1A/NR2B NMDA receptor subunits. D 1 -H 3 -NMDA receptor complexes were confirmed by BRET combined with fluorescence complementation. The endogenous expression of complexes in mouse cortex was determined by PLA and similar expression was observed in wild-type and APP/PS1 mice. Consistent with allosteric receptor-receptor interactions within the complex, H 3 receptor antagonists reduced NMDA or D 1 receptor-mediated excitotoxic cell death in cortical organotypic cultures. Moreover, H 3 receptor antagonists reverted the toxicity induced by ß 1-42 -amyloid peptide. Thus, histamine H 3 receptors in D 1 -H 3 -NMDA heteroreceptor complexes arise as promising targets to prevent neurodegeneration.

  14. Effect of thiopental sodium on N-methyl-D-aspartate-gated currents.

    PubMed

    Liu, Hongliang; Dai, Tijun; Yao, Shanglong

    2006-05-01

    N-methyl-D-aspartate (NMDA) receptors in the prefrontal cortex (PFC) are closely related with the excitability of pyramidal neurons and PFC function. As the effect of thiopental sodium on the central nervous system may partly result from the inhibition of PFC NMDA receptors, we investigated the effect of thiopental sodium with different concentrations on NMDA-gated currents in acutely dissociated rat PFC pyramidal neurons. We sought to determine whether thiopental sodium inhibits NMDA receptor function. Three to four week old male Sprague-Dawley rats were sacrificed and the PFC was dissected. Pyramidal neurons from the PFC were prepared and standard whole-cell patch clamp recordings were performed. Escalating concentrations from 3-1000 microM NMDA were applied 100 microm from the pyramidal cells, and the concentration in the effect compartment related to 50% effect (EC50) of NMDA was determined for the ensuing experiments. One hundred microM NMDA alone (control) or NMDA with different concentrations (10-1000 microM) of thiopental sodium were applied. After the inhibitory concentration, in 50% of NMDA effect (IC50) of thiopental sodium was established this IC50 and NMDA 3-1000 microM were applied 100 microm from the pyramidal cells. The EC50 value of NMDA under the effect of IC50 thiopental sodium was determined. N-methyl-D-aspartate induced inward currents in a concentration-dependent manner, which were completely antagonized by 50 microM AP5. The maximal amplitude of NMDA-induced current was 1.15 +/- 0.27 nA. The EC50 of NMDA was 53.6 +/- 12.4 microM. The NMDA (100 microM)-gated current was inhibited by thiopental sodium in a concentration-dependent manner, and the IC50 of thiopental sodium was 33.6 +/- 6.1 microM. Under the effect of 33.6 microM thiopental sodium, the maximal amplitude of NMDA-induced current was 0.87 +/- 0.17 nA. The concentration-response curve of NMDA was shifted rightwards. The EC50 of NMDA was 128 +/- 15 microM, which was greater than that

  15. Anti-N-methyl-D-aspartate (NMDA) receptor encephalitis: an unusual cause of autistic regression in a toddler.

    PubMed

    Scott, Ori; Richer, Lawrence; Forbes, Karen; Sonnenberg, Lyn; Currie, Angela; Eliyashevska, Myroslava; Goez, Helly R

    2014-05-01

    Anti N-methyl-d-aspartate (NMDA) receptor encephalitis in children is associated with psychiatric changes, seizures, and dyskinesias. We present the first report of autistic regression in a toddler caused by this entity. A 33-month-old boy presented with decreased appetite, irritability, and insomnia following an upper respiratory tract infection. Over the next few weeks he lost language and social skills, and abnormal movements of his hand developed. Within a month, this patient came to fit the diagnostic criteria for autistic spectrum disorder. Upon investigation, anti-NMDA receptor antibodies were found in the boy's cerebrospinal fluid. He was treated with intravenous immunoglobulins and steroids, resulting in reacquisition of language and social skills and resolution of movements. Our case emphasizes the significance of suspecting anti-NMDA receptor encephalitis as the cause of autistic regression, even in an age group where the diagnosis of autistic spectrum disorder is typically made, and especially when presentation follows a febrile illness.

  16. Identification of N-Methyl-d-aspartic Acid (NMDA) Receptor Subtype-specific Binding Sites That Mediate Direct Interactions with Scaffold Protein PSD-95*

    PubMed Central

    Cousins, Sarah L.; Stephenson, F. Anne

    2012-01-01

    N-methyl-d-aspartate (NMDA) neurotransmitter receptors and the postsynaptic density-95 (PSD-95) membrane-associated guanylate kinase (MAGUK) family of scaffolding proteins are integral components of post-synaptic macromolecular signaling complexes that serve to propagate glutamate responses intracellularly. Classically, NMDA receptor NR2 subunits associate with PSD-95 MAGUKs via a conserved ES(E/D)V amino acid sequence located at their C termini. We previously challenged this dogma to demonstrate a second non-ES(E/D)V PSD-95-binding site in both NMDA receptor NR2A and NR2B subunits. Here, using a combination of co-immunoprecipitations from transfected mammalian cells, yeast two-hybrid interaction assays, and glutathione S-transferase (GST) pulldown assays, we show that NR2A subunits interact directly with PSD-95 via the C-terminal ESDV motif and additionally via an Src homology 3 domain-binding motif that associates with the Src homology 3 domain of PSD-95. Peptide inhibition of co-immunoprecipitations of NR2A and PSD-95 demonstrates that both the ESDV and non-ESDV sites are required for association in native brain tissue. Furthermore, we refine the non-ESDV site within NR2B to residues 1149–1157. These findings provide a molecular basis for the differential association of NMDA receptor subtypes with PSD-95 MAGUK scaffold proteins. These selective interactions may contribute to the organization, lateral mobility, and ultimately the function of NMDA receptor subtypes at synapses. Furthermore, they provide a more general molecular mechanism by which the scaffold, PSD-95, may discriminate between potential interacting partner proteins. PMID:22375001

  17. [N-methyl-D-aspartate receptor antibody encephalitis: value of immunomodulatory therapy].

    PubMed

    Le Moigno, L; Ternant, D; Paintaud, G; Thibault, G; Cloarec, S; Tardieu, M; Lagrue, E; Castelnau, P

    2014-06-01

    Anti-N-methyl-D-aspartate receptor (NMDA-R) encephalitis is little known to pediatricians and likely underdiagnosed. The child's vital and cognitive prognosis is at stake. The use of immunomodulatory drugs, such as rituximab has led to spectacular results, but many questions remain about its mode of action in this type of pathology. We report the case of a 6-year-old girl with no medical history, admitted for status epilepticus preceded by behavior symptoms and sleep disorders. Gradually, the child became bedridden, mute, and animated by predominantly orofacial dyskinesia. Examinations were normal (cerebrospinal fluid [CSF] analysis, brain MRI). The diagnosis was established by the presence of NMDA-R antibodies in the CSF. After exclusion of a tumor-associated syndrome, treatment was started initially by intravenous immunoglobulins, then by plasma exchange, and finally rituximab. The patient was cured with rituximab despite an unusually early recovery of the B-cell pool. Anti-N-methyl-D-aspartate receptor (NMDA-R) encephalitis is a severe but potentially reversible neurologic disorder only recently described, even in childhood. It may be reversible without sequelae if diagnosed and treated early. The use of immunomodulatory therapy, such as rituximab seemingly improves the outcome. Immunological monitoring is needed to better understand its mechanism of action in autoimmune diseases of the nervous system in childhood. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  18. Citrate Modulates the Regulation by Zn2+ of N-Methyl-D-Aspartate Receptor-Mediated Channel Current and Neurotransmitter Release

    NASA Astrophysics Data System (ADS)

    Westergaard, Niels; Banke, Tue; Wahl, Philip; Sonnewald, Ursula; Schousboe, Arne

    1995-04-01

    The effect of the two metal-ion chelators EDTA and citrate on the action of N-methyl-D-aspartate (NMDA) receptors was investigated by use of cultured mouse cerebellar granule neurons and Xenopus oocytes, respectively, to monitor either NMDA-evoked transmitter release or membrane currents. Transmitter release from the glutamatergic neurons was determined by superfusion of the cells after preloading with the glutamate analogue D-[^3H]aspartate. The oocytes were injected with mRNA isolated from mouse cerebellum and, after incubation to allow translation to occur, currents mediated by NMDA were recorded electrophysiologically by voltage clamp at a holding potential of -80 mV. It was found that citrate as well as EDTA could attenuate the inhibitory action of Zn2+ on NMDA receptor-mediated transmitter release from the neurons and membrane currents in the oocytes. These effects were specifically related to the NMDA receptor, since the NMDA receptor antagonist MK-801 abolished the action and no effects of Zn2+ and its chelators were observed when kainate was used to selectively activate non-NMDA receptors. Since it was additionally demonstrated that citrate (and EDTA) preferentially chelated Zn2+ rather than Ca2+, the present findings strongly suggest that endogenous citrate released specifically from astrocytes into the extracellular space in the brain may function as a modulator of NMDA receptor activity. This is yet another example of astrocytic influence on neuronal activity.

  19. Psychiatric Autoimmunity: N-Methyl-D-Aspartate Receptor IgG and Beyond.

    PubMed

    Kruse, Jennifer L; Lapid, Maria I; Lennon, Vanda A; Klein, Christopher J; Toole, Orna O'; Pittock, Sean J; Strand, Edythe A; Frye, Mark A; McKeon, Andrew

    2015-01-01

    Descriptions of psychiatric autoimmunity beyond N-methyl-D-aspartate (NMDA) receptor encephalitis are sparse. To report the autoimmune psychiatric spectrum currently recognized in Mayo Clinic practice. Medical record review, testing of stored serum and cerebrospinal fluid for IgGs reactive with synaptic receptors and ion channels, neuronal nuclear and cytoplasmic antigens (including glutamic acid decarboxylase 65-kDa isoform) and case-control comparison were conducted. Patients were categorized into group 1, all adult psychiatric inpatients tested for neural autoantibodies (2002-2011; n = 213), and group 2, all Mayo NMDA receptor IgG-positive patients (2009-2013; n = 13); healthy control subjects were also included (n = 173). In group 1, at least 1 serum autoantibody (but not NMDA receptor IgG) was detected in 36 of 213 psychiatric inpatients. In total, 12 patients were determined retrospectively to have high-likelihood autoimmune encephalitic diagnoses. The most commonly detected autoantibody specificities were voltage-gated potassium channel ([Kv1] VGKC) complex (6) and calcium channel (P/Q type or N type; 5). Symptoms seen were as follows: depressive (8), anxious (7), psychotic (7), disorganized (5), suicidal (3), manic (1) and catatonic (1). In group 2, among 13 NMDA receptor IgG-positive patients, 12 had encephalitis; their psychiatric symptoms were as follows: depressive (9), catatonic (9), disorganized (8), anxious (8), psychotic (7), manic (6), and suicidal (3). Catatonic symptoms were more common in the 12 NMDA receptor IgG-positive patients than in the 12 group 1 patients with high likelihood of encephalitis (p = 0.002). Antibody positivities were usually low positive in value among healthy controls (12 of 16 vs 3 of 12 group 1 encephalitis cases, p = 0.025). NMDA receptor IgG was not detected in any healthy control subject. A spectrum of psychiatric autoimmunity beyond NMDA-R IgG may be under-recognized. Diagnosis is facilitated by combining results of

  20. Characterization of l-Theanine Excitatory Actions on Hippocampal Neurons: Toward the Generation of Novel N-Methyl-d-aspartate Receptor Modulators Based on Its Backbone.

    PubMed

    Sebih, Fatiha; Rousset, Matthieu; Bellahouel, Salima; Rolland, Marc; de Jesus Ferreira, Marie Celeste; Guiramand, Janique; Cohen-Solal, Catherine; Barbanel, Gérard; Cens, Thierry; Abouazza, Mohammed; Tassou, Adrien; Gratuze, Maud; Meusnier, Céline; Charnet, Pierre; Vignes, Michel; Rolland, Valérie

    2017-08-16

    l-Theanine (or l-γ-N-ethyl-glutamine) is the major amino acid found in Camellia sinensis. It has received much attention because of its pleiotropic physiological and pharmacological activities leading to health benefits in humans, especially. We describe here a new, easy, efficient, and environmentally friendly chemical synthesis of l-theanine and l-γ-N-propyl-Gln and their corresponding d-isomers. l-Theanine, and its derivatives obtained so far, exhibited partial coagonistic action at N-methyl-d-aspartate (NMDA) receptors, with no detectable agonist effect at other glutamate receptors, on cultured hippocampal neurons. This activity was retained on NMDA receptors expressed in Xenopus oocytes. In addition, both GluN2A and GluN2B containing NMDA receptors were equally modulated by l-theanine. The stereochemical change from l-theanine to d-theanine along with the substitution of the ethyl for a propyl moiety in the γ-N position of l- and d-theanine significantly enhanced the biological efficacy, as measured on cultured hippocampal neurons. l-Theanine structure thus represents an interesting backbone to develop novel NMDA receptor modulators.

  1. Inhibition of N-methyl-D-aspartate receptors increases paraoxon-induced apoptosis in cultured neurons

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wu Xuan; Tian Feng; Okagaki, Peter

    2005-10-01

    Organophosphorus (OP) compounds, used as insecticides and chemical warfare agents, are potent neurotoxins. We examined the neurotoxic effect of paraoxon (O,O-diethyl O-p-nitrophenyl phosphate), an organophosphate compound, and the role of NMDA receptors as a mechanism of action in cultured cerebellar granule cells. Paraoxon is neurotoxic to cultured rat cerebellar granule cells in a time- and concentration-dependent manner. Cerebellar granule cells are less sensitive to the neurotoxic effects of paraoxon on day in vitro (DIV) 4 than neurons treated on DIV 8. Surprisingly, the N-methyl-D-aspartate (NMDA) receptor antagonist, MK-801, enhances paraoxon-mediated neurotoxicity suggesting that NMDA receptors may play a protective role.more » Pretreatment with a subtoxic concentration of N-methyl-D-aspartate (NMDA) [100 {mu}M] protects about 40% of the vulnerable neurons that would otherwise die from paraoxon-induced neurotoxicity. Moreover, addition of a neuroprotective concentration of NMDA 3 h after treatment with paraoxon provides the same level of protection. Because paraoxon-mediated neuronal cell death is time-dependent, we hypothesized that apoptosis may be involved. Paraoxon increases apoptosis about 10-fold compared to basal levels. The broad-spectrum caspase inhibitor (Boc-D-FMK) and the caspase-9-specific inhibitor (Z-LEHD-FMK) protect against paraoxon-mediated apoptosis, paraoxon-stimulated caspase-3 activity and neuronal cell death. MK-801 increases, whereas NMDA blocks paraoxon-induced apoptosis and paraoxon-stimulated caspase-3 activity. These results suggest that activation of NMDA receptors protect neurons against paraoxon-induced neurotoxicity by blocking apoptosis initiated by paraoxon.« less

  2. Approach to the Management of Pediatric-Onset Anti-N-Methyl-d-Aspartate (Anti-NMDA) Receptor Encephalitis: A Case Series.

    PubMed

    Brenton, J Nicholas; Kim, Joshua; Schwartz, Richard H

    2016-08-01

    Anti-N-methyl-d-aspartate (anti-NMDA) receptor encephalitis is a treatable cause of autoimmune encephalitis. It remains unclear if the natural history of this disease is altered by choice of acute therapy or the employment of chronic immunotherapy. Chart review was undertaken for pediatric patients diagnosed with anti-NMDA receptor encephalitis. Data obtained included patient demographics, disease manifestations, treatment course, and clinical outcomes. Ten patients with anti-NMDA receptor encephalitis were identified. All patients were treated with immunotherapy in the acute period, and all patients experienced good recovery. Neurologic relapse did not occur in any patient. All patients received varied forms of chronic immunosuppression to prevent relapses. Complications of chronic immunotherapy occurred in 50% of patients. The benefits of chronic immunotherapy and the duration of use should be carefully weighed against the risks. Complications from immunotherapy are not uncommon and can be serious. Clinical trials assessing the benefit of long-term immunotherapy in this population are needed. © The Author(s) 2016.

  3. Ionotropic and metabotropic glutamate receptor mediation of glucocorticoid-induced apoptosis in hippocampal cells and the neuroprotective role of synaptic N-methyl-D-aspartate receptors.

    PubMed

    Lu, J; Goula, D; Sousa, N; Almeida, O F X

    2003-01-01

    Glutamate receptors have been proposed to mediate the apoptotic actions of glucocorticoids in hippocampal cells. To further analyze the role of glutamate receptors in this process, we pretreated primary hippocampal cells from neonatal (postnatal day 4) rats with antagonists of ionotropic glutamate receptor (iGluR) and metabotropic glutamate receptor (mGluR) antagonists before exposure to the specific glucocorticoid receptor agonist dexamethasone (DEX) at a dose of 1 microM. Dizocilpine (MK801; a general N-methyl-D-aspartic acid [NMDA] receptor antagonist, NMDAR antagonist) and ifenprodil (a specific ligand of the NMDAR 2B subunit, NR2B), were used to block iGluR; (RS)-alpha-ethyl-4-carboxyphenylglycine (E4CPG) and (RS)-alpha-cyclopropyl-4-phosphonophenyl-glycine (CPPG) were employed as I/II (E4CPG) and II/III (CPPG) mGluR antagonists. Blockade of iGluR resulted in a significant attenuation of DEX-induced cell death; the finding that ifenprodil exerted a similar potency to MK801 demonstrates the involvement of NR2B receptors in glucocorticoid-induced cell death. Apoptosis accounted for a significant amount of the cell loss observed, as detected by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling histochemistry for the in situ labeling of DNA breaks; apoptotic cells were distinguished from necrosis on the basis of morphological criteria, including chromatin condensation, membrane blebbing and presence of apoptotic bodies. Treatment with E4CPG and CPPG completely abolished the apoptotic response to DEX, thus showing the additional contribution of mGluR to the phenomenon. Further, dose-response studies with NMDA revealed that whereas high (10 microM) doses of NMDA themselves elicit cytotoxic responses, low (1-5 microM) concentrations of NMDA can effectively oppose DEX-induced cell death. Interestingly, the neuroprotective actions of low dose NMDA stimulation were abolished when either synaptic or extrasynaptic NMDA receptors were blocked with MK801

  4. Synthesis and characterization of a series of diarylguanidines that are noncompetitive N-methyl-D-aspartate receptor antagonists with neuroprotective properties

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Keana, J.F.W.; McBurney, R.N.; Scherz, M.W.

    1989-07-01

    Four diarylguanidine derivatives were synthesized. These compounds were found to displace, at submicromolar concentrations, {sup 3}H-labeled 1-(1-(2-thienyl)cyclohexyl)piperidine and (+)-({sup 3}H)MK-801 from phencyclidine receptors in brain membrane preparations. In electrophysiological experiments the diarylguanidines blocked N-methyl-D-aspartate (NMDA)-activated ion channels. These dairylguanidines also protected rat hippocampal neurons in vitro from glutamate-induced cell death. The results show that some diarylguanidines are noncompetitive antagonists of NMDA receptor-mediated responses and have the neuroprotective property that is commonly associated with blockers of the NMDA receptor-gated cation channel. Diarylguanidines are structurally unrelated to known blockers of NMDA channels and, therefore, represent a new compound series for the developmentmore » of neuroprotective agents with therapeutic value in patients suffering from stroke, from brain or spinal cord trauma, from hypoglycemia, and possibly from brain ischemia due to heart attack.« less

  5. Kinetic Contributions to Gating by Interactions Unique to N-methyl-d-aspartate (NMDA) Receptors*

    PubMed Central

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

    2015-01-01

    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

  6. Extrasynaptic N-Methyl-d-aspartate (NMDA) Receptor Stimulation Induces Cytoplasmic Translocation of the CDKL5 Kinase and Its Proteasomal Degradation*

    PubMed Central

    Rusconi, Laura; Kilstrup-Nielsen, Charlotte; Landsberger, Nicoletta

    2011-01-01

    Mutations in the X-linked gene cyclin-dependent kinase-like 5 (CDKL5) have been found in patients with epileptic encephalopathy characterized by early onset intractable epilepsy, including infantile spasms and other types of seizures, severe developmental delay, and often the development of Rett syndrome-like features. Despite its clear involvement in proper brain development, CDKL5 functions are still far from being understood. In this study, we analyzed the subcellular localization of the endogenous kinase in primary murine hippocampal neurons. CDKL5 was localized both in nucleus and cytoplasm and, conversely to proliferating cells, did not undergo constitutive shuttling between these compartments. Nevertheless, glutamate stimulation was able to induce the exit of the kinase from the nucleus and its subsequent accumulation in the perinuclear cytoplasm. Moreover, we found that sustained glutamate stimulation promoted CDKL5 proteasomal degradation. Both events were mediated by the specific activation of extrasynaptic pool of N-methyl-d-aspartate receptors. Proteasomal degradation was also induced by withdrawal of neurotrophic factors and hydrogen peroxide treatment, two different paradigms of cell death. Altogether, our results indicate that both subcellular localization and expression of CDKL5 are modulated by the activation of extrasynaptic N-methyl-d-aspartate receptors and suggest regulation of CDKL5 by cell death pathways. PMID:21832092

  7. Extrasynaptic N-methyl-D-aspartate (NMDA) receptor stimulation induces cytoplasmic translocation of the CDKL5 kinase and its proteasomal degradation.

    PubMed

    Rusconi, Laura; Kilstrup-Nielsen, Charlotte; Landsberger, Nicoletta

    2011-10-21

    Mutations in the X-linked gene cyclin-dependent kinase-like 5 (CDKL5) have been found in patients with epileptic encephalopathy characterized by early onset intractable epilepsy, including infantile spasms and other types of seizures, severe developmental delay, and often the development of Rett syndrome-like features. Despite its clear involvement in proper brain development, CDKL5 functions are still far from being understood. In this study, we analyzed the subcellular localization of the endogenous kinase in primary murine hippocampal neurons. CDKL5 was localized both in nucleus and cytoplasm and, conversely to proliferating cells, did not undergo constitutive shuttling between these compartments. Nevertheless, glutamate stimulation was able to induce the exit of the kinase from the nucleus and its subsequent accumulation in the perinuclear cytoplasm. Moreover, we found that sustained glutamate stimulation promoted CDKL5 proteasomal degradation. Both events were mediated by the specific activation of extrasynaptic pool of N-methyl-d-aspartate receptors. Proteasomal degradation was also induced by withdrawal of neurotrophic factors and hydrogen peroxide treatment, two different paradigms of cell death. Altogether, our results indicate that both subcellular localization and expression of CDKL5 are modulated by the activation of extrasynaptic N-methyl-D-aspartate receptors and suggest regulation of CDKL5 by cell death pathways.

  8. N-methyl-D-aspartate increases acetylcholine release from rat striatum and cortex: its effect is augmented by choline

    NASA Technical Reports Server (NTRS)

    Ulus, I. H.; Buyukuysal, R. L.; Wurtman, R. J.

    1992-01-01

    We examined the effects of N-methyl-D-aspartate (NMDA), a glutamate agonist, and of glutamate itself, on acetylcholine (ACh) release from superfused rat striatal slices. In a Mg(++)-free medium, NMDA (32-1000 microM) as well as glutamate (1 mM) increased basal ACh release by 35 to 100% (all indicated differences, P less than .05), without altering tissue ACh or choline contents. This augmentation was blocked by Mg++ (1.2 mM) or by MK-801 (10 microM). Electrical stimulation (15 Hz, 75 mA) increased ACh release 9-fold (from 400 to 3660 pmol/mg of protein): this was enhanced (to 4850 pmol/mg of protein) by NMDA (100 microM). ACh levels in stimulated slices fell by 50 or 65% depending on the absence or presence of NMDA. The addition of choline (40 microM) increased ACh release both basally (570 pmol/mg of protein) and with electrical stimulation (6900 pmol/mg of protein). In stimulated slices choline acted synergistically with NMDA, raising ACh release to 10,520 pmol/mg of protein. The presence of choline also blocked the fall in tissue ACh. No treatment affected tissue phospholipid or protein levels. NMDA (32-320 microM) also augmented basal ACh release from cortical but not hippocampal slices. Choline efflux from striatal and cortical (but not hippocampal) slices decreased by 34 to 50% in Mg(++)-free medium. These data indicate that NMDA-like drugs may be useful, particularly in combination with choline, to enhance striatal and cortical cholinergic activity. ACh release from rat hippocampus apparently is not affected by NMDA receptors.

  9. N-methyl-D-aspartate neurotoxicity in hippocampal slices: protection by aniracetam.

    PubMed

    Pizzi, M; Consolandi, O; Memo, M; Spano, P

    1995-03-14

    Aniracetam, a drug known to elicit cognition enhancing properties in both animals and humans, was found to counteract the neurotoxicity induced by excitatory amino acids in primary cultures of cerebellar neurons. We report here that aniracetam prevents the neurotoxic effect induced by N-methyl-D-aspartate (NMDA) in rat hippocampal slices. Time-course experiments showed that the aniracetam-induced neuroprotection does not require preincubation of the slices with the drug. Maximal effective concentration of aniracetam was 10 microM. Since the NMDA-mediated cell death in hippocampal slices is considered a valuable experimental model of ischemia, these results suggest a possible novel therapeutic application for aniracetam.

  10. Choline exposure reduces potentiation of N-methyl-D-aspartate toxicity by corticosterone in the developing hippocampus.

    PubMed

    Mulholland, Patrick J; Self, Rachel L; Harris, Barton R; Littleton, John M; Prendergast, Mark A

    2004-11-25

    Exposure to high levels of glucocorticoids (GCs) may adversely affect neuronal viability, particularly in the developing hippocampus, via increased function or sensitivity of N-methyl-D-aspartate (NMDA)-type glutamate receptors. Conversely, choline supplementation in the developing brain may reduce the severity of subsequent insult. The present studies aimed to examine the extent to which short-term exposure to high concentrations of corticosterone would produce neuronal injury mediated by NMDA receptor activity. These studies also assessed the ability of choline to prevent this form of injury via interactions with nicotinic acetylcholine receptors (nAChRs) expressing the alpha7 subunit. Organotypic hippocampal slice cultures derived from neonatal rat were pre-treated for 72 h with corticosterone (100 nM) alone or with choline (0.1-10 mM), prior to a brief (1 h) NMDA exposure (5 microM). NMDA exposure produced significant cellular damage, reflected as increased fluorescence of the non-vital marker propidium iodide, in the CA1 region. While exposure to corticosterone alone did not produce damage, pre-treatment of cultures with corticosterone markedly exacerbated NMDA-induced toxicity. Pre-treatment with choline (> or =1 mM) alone or in combination with corticosterone markedly reduced subsequent NMDA toxicity, effects blocked by co-exposure to methyllycaconitine (100 nM), an antagonist active at nAChRs expressing the alpha7 subunit. These data suggest that even short-term exposure to high concentrations of GCs may adversely affect neuronal viability and that choline supplementation protects the brain from NMDA receptor-mediated damage, including that associated with hypercortisolemia.

  11. Pharmacological specificity of N-methyl-D-aspartate discrimination in rats.

    PubMed

    Grech, D M; Willetts, J; Balster, R L

    1993-04-01

    The purpose of this study was to provide further information on the usefulness of N-methyl-D-aspartate (NMDA) discrimination in rats as a behavioral model for NMDA receptor activation. The pharmacological specificity of the NMDA discriminative stimulus was examined in rats trained to discriminate 30 mg/kg, i.p. NMDA from saline using a 2-lever fixed-ratio (FR) 32 food reinforcement schedule. Pharmacologically diverse centrally-acting agents were examined for their ability to substitute for NMDA. Morphine did not substitute for NMDA; neither did the central stimulants, caffeine and (+)-amphetamine, which produced a maximum mean of only 16 and 35% NMDA-lever responding, respectively. Pentylenetetrazol and picrotoxin also did not substitute for NMDA. Compounds interacting with cholinergic neurotransmission including nicotine, physostigmine, arecoline and mecamylamine, produced at best, only intermediate levels of NMDA-lever responding (32-61%), with the highest levels of NMDA-lever responding generally occurring at doses that also reduced rates of responding. These results suggest that the discriminative stimulus properties of NMDA are dissimilar from those of a number of centrally-acting drugs. Combined with the results of studies indicating that the NMDA discriminative stimulus can be antagonized by competitive NMDA antagonists, these results provide further evidence that NMDA receptor activation is the basis of NMDA discrimination and that this model may be useful for studying site-selective NMDA agonists and antagonists.

  12. Probing N-methyl-D-aspartate receptor desensitization with the substituted-cysteine accessibility method.

    PubMed

    Thomas, Christopher G; Krupp, Johannes J; Bagley, Elena E; Bauzon, Reginald; Heinemann, Stephen F; Vissel, Bryce; Westbrook, Gary L

    2006-04-01

    Several forms of macroscopic N-methyl-D-aspartate (NMDA) receptor desensitization affect the amplitude and duration of postsynaptic responses. In addition to its functional significance, desensitization provides one means to examine the conformational coupling of ligand binding to channel gating. Segments flanking the ligand binding domain in the extracellular N terminus of the NMDA receptor NR2 subunit influence the glycine-independent form of desensitization. The NR2A pre-M1 region, the linker between the glutamate binding domain and the channel pore, plays a critical role in desensitization. Thus, we used the substituted-cysteine accessibility method to scan the accessibility of residues in the pre-M1 region and the first transmembrane domain (M1) of NR2A. Cysteine mutants were expressed with NR1 in human embryonic kidney 293 cells and were assayed by whole-cell recording. With activation of the receptor by glutamate and glycine, only a single mutant, V557C, which is located at the beginning of M1, led to irreversible inhibition by the methanethiosulfonate derivative methanethiosulfonate ethyltrimethylammonium (MTSET). The NR2 ligand glutamate was insufficient on its own to induce modification of V557C by MTSET, suggesting that the change in accessibility required channel gating. The rate of MTSET modification of the homologous residue on NR1 (NR1-1a(L562C)/NR2A) was much slower than V557C. We also substituted cysteine in the V557 site of mutant subunits that exhibit either enhanced or reduced desensitization. Modification by MTSET correlated with the degree of desensitization for these subunits, suggesting that V557C is a sensitive detector of desensitization gating.

  13. Differential Effects of TM4 Tryptophan Mutations on Inhibition of N-Methyl-D-Aspartate Receptors by Ethanol and Toluene

    PubMed Central

    Smothers, C. Thetford; Woodward, John J.

    2017-01-01

    The voluntary use and abuse of alcohol and inhalants is a recognized health problem throughout the world. Previous studies have shown that these agents affect brain function in a variety of ways including direct inhibition of key ion channels that regulate neuronal excitability. Among these, the N-methyl-D-aspartate (NMDA) receptor is particularly important given its key role in glutamatergic synaptic transmission, neuronal plasticity and learning and memory. Previous studies from this laboratory and others have identified key residues within transmembrane (TM) domains of the NMDA receptor that appear to regulate its sensitivity to alcohol and anesthetics. In this study, we extend these findings and examine the role of a TM4 residue in modulating sensitivity of recombinant NMDA receptors to ethanol and toluene. HEK293 cells were transfected with GluN1-1a and either wild-type or tryptophan-substituted GluN2(A–D) subunits and whole-cell currents were recorded using patch-clamp electrophysiology in the absence or presence of ethanol or toluene. Both ethanol (100 mM) and toluene (1 or 3 mM) reversibly inhibited glutamate-activated currents from wild-type NMDARs with GluN2B containing receptors showing heightened sensitivity to either agent. Substitution of tryptophan (W) at positions 825, 826, 823 or 850 in the TM4 domain of GluN2A, GluN2B, GluN2C or GluN2D subunits; respectively, significantly reduced the degree of inhibition by ethanol. In contrast, toluene inhibition of glutamate-activated currents in cells expressing the TM4-W mutants was not different from that of the wild-type controls. These data suggest that despite similarities in their action on NMDARs, ethanol and toluene may act at different sites to reduce ion flux through NMDA receptors. PMID:27814790

  14. Differential effects of TM4 tryptophan mutations on inhibition of N-methyl-d-aspartate receptors by ethanol and toluene.

    PubMed

    Smothers, C Thetford; Woodward, John J

    2016-11-01

    The voluntary use and abuse of alcohol and inhalants is a recognized health problem throughout the world. Previous studies have shown that these agents affect brain function in a variety of ways including direct inhibition of key ion channels that regulate neuronal excitability. Among these, the N-methyl-d-aspartate (NMDA) receptor is particularly important given its key role in glutamatergic synaptic transmission, neuronal plasticity and learning and memory. Previous studies from this laboratory and others have identified key residues within transmembrane (TM) domains of the NMDA receptor that appear to regulate its sensitivity to alcohol and anesthetics. In this study, we extend these findings and examine the role of a TM4 residue in modulating sensitivity of recombinant NMDA receptors to ethanol and toluene. HEK293 cells were transfected with GluN1-1a and either wild-type or tryptophan-substituted GluN2(A-D) subunits and whole-cell currents were recorded using patch-clamp electrophysiology in the absence or presence of ethanol or toluene. Both ethanol (100 mM) and toluene (1 or 3 mM) reversibly inhibited glutamate-activated currents from wild-type NMDARs with GluN2B containing receptors showing heightened sensitivity to either agent. Substitution of tryptophan (W) at positions 825, 826, 823 or 850 in the TM4 domain of GluN2A, GluN2B, GluN2C or GluN2D subunits; respectively, significantly reduced the degree of inhibition by ethanol. In contrast, toluene inhibition of glutamate-activated currents in cells expressing the TM4-W mutants was not different from that of the wild-type controls. These data suggest that despite similarities in their action on NMDARs, ethanol and toluene may act at different sites to reduce ion flux through NMDA receptors. Copyright © 2016 Elsevier Inc. All rights reserved.

  15. Novel pyrrolinones as N-methyl-D-aspartate receptor antagonists.

    PubMed

    Poschenrieder, Hermann; Stachel, Hans-Dietrich; Höfner, Georg; Mayer, Peter

    2005-04-01

    A series of oximes, deriving from 2-arylidene-pyrroline-3,4-diones (7, 8, 22, 23) has been prepared. The presence of tautomers in their solutions has been established by spectroscopic means. The compounds reacted with diazomethane chiefly by N-methylation forming nitrones (10, 11). The analogously prepared 2-arylidene-4-nitropyrrolin-3-ones (12, 13, 24, 25), formally derived from nitrotetramic acids, yielded nitronic acid esters (14, 15, 26) upon reaction with diazomethane. The structures were elucidated by spectral evidence and-in the case of compounds 10 and 20b-by X-ray diffraction analysis. The binding affinity of some of the new compounds toward the N-methyl-d-aspartate (NMDA) (glycine site) receptor has been measured thus providing the basis for further structure-activity relationship studies. Oxime 8b showed the highest binding potency (Ki= 9.2 microM).

  16. Agmatine protects against cell damage induced by NMDA and glutamate in cultured hippocampal neurons

    PubMed Central

    Wang, Wei-Ping; Iyo, Abiye H.; Miguel-Hidalgo, Javier; Regunathan, Soundar; Zhu, Meng-Yang

    2010-01-01

    Agmatine is a polyamine and has been considered as a novel neurotransmitter or neuromodulator in the central nervous system. In the present study, the neuroprotective effect of agmatine against cell damage caused by N-methyl-d-aspartate (NMDA) and glutamate was investigated in cultured rat hippocampal neurons. Lactate dehydrogenase (LDH) activity assay, β-tubulin III immunocytochemical staining and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate (dUTP) nick end-labeling (TUNEL) assay were conducted to detect cell damage. Exposure of 12-day neuronal cultures of rat hippocampus to NMDA or glutamate for 1 h caused a concentration-dependent neurotoxicity, as indicated by the significant increase in released LDH activities. Addition of 100 µM agmatine into media ablated the neurotoxicity induced by NMDA or glutamate, an effect also produced by the specific NMDA receptor antagonist dizocilpine hydrogen maleate (MK801). Arcaine, an analog of agmatine with similar structure as agmatine, fully prevented the NMDA- or glutamate-induced neuronal damage. Spermine and putrescine, the endogenous polyamine and metabolic products of agmatine without the guanidine moiety of agmatine, failed to show this effect, indicating a structural relevance for this neuroprotection. Immunocytochemical staining and TUNEL assay confirmed the findings in the LDH measurement. That is, agmatine and MK801 markedly attenuated NMDA-induced neuronal death and significantly reduced TUNEL-positive cell numbers induced by exposure of cultured hippocampal neurons to NMDA. Taken together, these results demonstrate that agmatine can protect cultured hippocampal neurons from NMDA- or glutamate-induced excitotoxicity, through a possible blockade of the NMDA receptor channels or a potential anti-apoptotic property. PMID:16546145

  17. N-Methyl-d-Aspartate (NMDA) Receptor Blockade Prevents Neuronal Death Induced by Zika Virus Infection

    PubMed Central

    Costa, Vivian V.; Del Sarto, Juliana L.; Rocha, Rebeca F.; Silva, Flavia R.; Doria, Juliana G.; Olmo, Isabella G.; Marques, Rafael E.; Queiroz-Junior, Celso M.; Foureaux, Giselle; Araújo, Julia Maria S.; Cramer, Allysson; Real, Ana Luíza C. V.; Ribeiro, Lucas S.; Sardi, Silvia I.; Ferreira, Anderson J.; Machado, Fabiana S.; de Oliveira, Antônio C.; Teixeira, Antônio L.; Nakaya, Helder I.; Souza, Danielle G.

    2017-01-01

    ABSTRACT Zika virus (ZIKV) infection is a global health emergency that causes significant neurodegeneration. Neurodegenerative processes may be exacerbated by N-methyl-d-aspartate receptor (NMDAR)-dependent neuronal excitoxicity. Here, we have exploited the hypothesis that ZIKV-induced neurodegeneration can be rescued by blocking NMDA overstimulation with memantine. Our results show that ZIKV actively replicates in primary neurons and that virus replication is directly associated with massive neuronal cell death. Interestingly, treatment with memantine or other NMDAR blockers, including dizocilpine (MK-801), agmatine sulfate, or ifenprodil, prevents neuronal death without interfering with the ability of ZIKV to replicate in these cells. Moreover, in vivo experiments demonstrate that therapeutic memantine treatment prevents the increase of intraocular pressure (IOP) induced by infection and massively reduces neurodegeneration and microgliosis in the brain of infected mice. Our results indicate that the blockade of NMDARs by memantine provides potent neuroprotective effects against ZIKV-induced neuronal damage, suggesting it could be a viable treatment for patients at risk for ZIKV infection-induced neurodegeneration. PMID:28442607

  18. Influence of Genetic Variants of the N-Methyl-D-Aspartate Receptor on Emotion and Social Behavior in Adolescents.

    PubMed

    Lee, Li-Ching; Cho, Ying-Chun; Lin, Pei-Jung; Yeh, Ting-Chi; Chang, Chun-Yen; Yeh, Ting-Kuang

    2016-01-01

    Considerable evidence has suggested that the epigenetic regulation of N-methyl-D-aspartate (NMDA) glutamate receptors plays a crucial role in neuropsychiatric disorders. Previous exploratory studies have been primarily based on evidence from patients and have rarely sampled the general population. This exploratory study examined the relationship of single-nucleotide polymorphism (SNP) variations in the genes encoding the NMDA receptor (i.e., GRIN1, GRIN2A, GRIN2B, GRIN2C, and GRIN2D) with emotion and social behavior in adolescents. For this study, 832 tenth-grade Taiwanese volunteers were recruited, and their scores from the Beck Youth Inventories were used to evaluate their emotional and social impairments. Based on these scores, GRIN1 (rs4880213) was significantly associated with depression and disruptive behavior. In addition, GRIN2B (rs7301328) was significantly associated with disruptive behavior. Because emotional and social impairment greatly influence learning ability, the findings of this study provide important information for clinical treatment and the development of promising prevention and treatment strategies, especially in the area of psychological adjustment.

  19. Iron Mediates N-Methyl-d-aspartate Receptor-dependent Stimulation of Calcium-induced Pathways and Hippocampal Synaptic Plasticity*

    PubMed Central

    Muñoz, Pablo; Humeres, Alexis; Elgueta, Claudio; Kirkwood, Alfredo; Hidalgo, Cecilia; Núñez, Marco T.

    2011-01-01

    Iron deficiency hinders hippocampus-dependent learning processes and impairs cognitive performance, but current knowledge on the molecular mechanisms underlying the unique role of iron in neuronal function is sparse. Here, we investigated the participation of iron on calcium signal generation and ERK1/2 stimulation induced by the glutamate agonist N-methyl-d-aspartate (NMDA), and the effects of iron addition/chelation on hippocampal basal synaptic transmission and long-term potentiation (LTP). Addition of NMDA to primary hippocampal cultures elicited persistent calcium signals that required functional NMDA receptors and were independent of calcium influx through L-type calcium channels or α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors; NMDA also promoted ERK1/2 phosphorylation and nuclear translocation. Iron chelation with desferrioxamine or inhibition of ryanodine receptor (RyR)-mediated calcium release with ryanodine-reduced calcium signal duration and prevented NMDA-induced ERK1/2 activation. Iron addition to hippocampal neurons readily increased the intracellular labile iron pool and stimulated reactive oxygen species production; the antioxidant N-acetylcysteine or the hydroxyl radical trapper MCI-186 prevented these responses. Iron addition to primary hippocampal cultures kept in calcium-free medium elicited calcium signals and stimulated ERK1/2 phosphorylation; RyR inhibition abolished these effects. Iron chelation decreased basal synaptic transmission in hippocampal slices, inhibited iron-induced synaptic stimulation, and impaired sustained LTP in hippocampal CA1 neurons induced by strong stimulation. In contrast, iron addition facilitated sustained LTP induction after suboptimal tetanic stimulation. Together, these results suggest that hippocampal neurons require iron to generate RyR-mediated calcium signals after NMDA receptor stimulation, which in turn promotes ERK1/2 activation, an essential step of sustained LTP. PMID:21296883

  20. N-Methyl D-Aspartate (NMDA) Receptor Antagonists and Memantine Treatment for Alzheimer’s Disease, Vascular Dementia and Parkinson’s Disease

    PubMed Central

    Olivares, David; Deshpande, Varun K.; Shi, Ying; Lahiri, Debomoy K.; Greig, Nigel H.; Rogers, Jack T.; Huang, Xudong

    2016-01-01

    Memantine, a partial antagonist of N-methyl-D-aspartate receptor (NMDAR), approved for moderate to severe Alzheimer’s disease (AD) treatment within the US and Europe under brand name Namenda (Forest), Axura and Akatinol (Merz), and Ebixa and Abixa (Lundbeck), may have potential in alleviating additional neurological conditions, such as vascular dementia (VD) and Parkinson’s disease (PD). In various animal models, memantine has been reported to be a neuroprotective agent that positively impacts both neurodegenerative and vascular processes. While excessive levels of glutamate result in neurotoxicity, in part through the over-activation of NMDARs, memantine—as a partial NMDAR antagonist, blocks the NMDA glutamate receptors to normalize the glutamatergic system and ameliorate cognitive and memory deficits. The key to memantine’s therapeutic action lies in its uncompetitive binding to the NMDAR through which low affinity and rapid off-rate kinetics of memantine at the level of the NMDAR-channel preserves the physiological function of the receptor, underpinning memantine’s tolerability and low adverse event profile. As the biochemical pathways evoked by NMDAR antagonism also play a role in PD and since no other drug is sufficiently effective to substitute for the first-line treatment of L-dopa despite its side effects, memantine may be useful in PD treatment with possibly fewer side effects. In spite of the relative modest nature of its adverse effects, memantine has been shown to provide only a moderate decrease in clinical deterioration in AD and VD, and hence efforts are being undertaken in the design of new and more potent memantine-based drugs to hopefully provide greater efficacy. PMID:21875407

  1. Vitamin C modulates glutamate transport and NMDA receptor function in the retina.

    PubMed

    Domith, Ivan; Socodato, Renato; Portugal, Camila C; Munis, Andressa F; Duarte-Silva, Aline T; Paes-de-Carvalho, Roberto

    2018-02-01

    Vitamin C (in the reduced form ascorbate or in the oxidized form dehydroascorbate) is implicated in signaling events throughout the central nervous system (CNS). In the retina, a high-affinity transport system for ascorbate has been described and glutamatergic signaling has been reported to control ascorbate release. Here, we investigated the modulatory role played by vitamin C upon glutamate uptake and N-methyl-d-aspartate (NMDA) receptor activation in cultured retinal cells or in intact retinal tissue using biochemical and imaging techniques. We show that both forms of vitamin C, ascorbate or dehydroascorbate, promote an accumulation of extracellular glutamate by a mechanism involving the inhibition of glutamate uptake. This inhibition correlates with the finding that ascorbate promotes a decrease in cell surface levels of the neuronal glutamate transporter excitatory amino acid transporter 3 in retinal neuronal cultures. Interestingly, vitamin C is prone to increase the activity of NMDA receptors but also promotes a decrease in glutamate-stimulated [ 3 H] MK801 binding and decreases cell membrane content of NMDA receptor glutamate ionotropic receptor subunit 1 (GluN1) subunits. Both compounds were also able to increase cAMP response element-binding protein phosphorylation in neuronal nuclei in a glutamate receptor and calcium/calmodulin kinase-dependent manner. Moreover, the effect of ascorbate is not blocked by sulfinpyrazone and then does not depend on its uptake by retinal cells. Overall, these data indicate a novel molecular and functional target for vitamin C impacting on glutamate signaling in retinal neurons. © 2017 International Society for Neurochemistry.

  2. Vinpocetine protects inner retinal neurons with functional NMDA glutamate receptors against retinal ischemia.

    PubMed

    Nivison-Smith, Lisa; Khoo, Pauline; Acosta, Monica L; Kalloniatis, Michael

    2018-02-01

    Retinal ischemia is involved in the pathogenesis of many major vision threatening diseases. Vinpocetine is a natural drug, which has a range of neuroprotective actions against retinal ischemia including modulating cation flow, improving metabolic activity and preventing apoptosis. The exact mechanism behind these actions remains unknown but may involve glutamate receptors, major components of the ischemic cascade. This study examined the effects of vinpocetine in association with specific ionotropic glutamate receptor agonists: N-methyl-D-aspartate (NMDA) and kainate. Vinpocetine's actions to improve cation channel permeability and cell marker immunoreactivity following ischemia appeared to be limited to NMDA activation with no changes observed following kainate stimulation. Vinpocetine's actions were lost in the presence of an NMDA receptor inhibitor further suggesting they may be secondary to NMDA receptor activation. NMDA receptor function was also necessary for vinpocetine's actions on glucose availability during ischemia but not lactate dehydrogenase (LDH) activity in the ischemic retina suggesting not all of vinpocetine's actions are linked to NMDA receptor function. These results may explain vinpocetine's effectiveness as a neuroprotective agent as the NMDA receptor is implicated in the pathogenesis of ischemia in a range of tissues of the central nervous system. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Role of Autoantibodies to N-Methyl-d-Aspartate (NMDA) Receptor in Relapsing Herpes Simplex Encephalitis: A Retrospective, One-Center Experience.

    PubMed

    Sutcu, Murat; Akturk, Hacer; Somer, Ayper; Tatli, Burak; Torun, Selda Hancerli; Yıldız, Edibe Pembegul; Şık, Guntulu; Citak, Agop; Agacfidan, Ali; Salman, Nuran

    2016-03-01

    Post-herpes simplex virus encephalitis relapses have been recently associated with autoimmunity driven by autoantibodies against N-methyl-d-aspartate (NMDA) receptors. Because it offers different treatment options, determination of this condition is important. Between 2011 and 2014, 7 children with proven diagnosis of herpes simplex virus encephalitis were identified in a university hospital of Istanbul. Two patients had neurologic relapse characterized mainly by movement disorders 2 to 3 weeks after initial encephalitis. The first patient received a second 14 days of acyclovir treatment together with antiepileptic drugs and left with severe neurologic sequelae. The second patient was found to be NMDA receptors antibody positive in the cerebrospinal fluid. She was treated with intravenous immunoglobulin and prednisolone. She showed substantial improvement, gradually regaining lost neurologic abilities. Post-herpes simplex virus encephalitis relapses may frequently be immune-mediated rather than a viral reactivation, particularly in children displaying movement disorders like choreoathetosis. Immunotherapy may provide benefit for this potentially devastating condition, like the case described in this report. © The Author(s) 2015.

  4. Synthesis of water-soluble polyamine derivatives effective as N-methyl-D-aspartate receptor antagonists.

    PubMed

    Masuko, Takashi; Yoshida, Shuhei; Metori, Koichi; Kizawa, Yasuo; Kusama, Tadashi; Miyake, Muneharu

    2010-06-01

    The novel water-soluble N-methyl-D-aspartate (NMDA) receptor antagonists, N-{4-[4-(4-Guanidinobutylamino)butylamino]butyl}-p-toluenesulfonamide trihydrochloride (1a, TsHSPMG), N-{4-[4-(4-Guanidinobutylamino)butylamino]butyl}butane-1-sulfonamide trihydrochloride (1b, BsHSPMG), N-{3-[4-(3-Guanidinopropylamino)butylamino]propyl}-p-toluenesulfonamide trihydrochroride (2a, TsSPMG) and N-{3-[4-(3-Guanidinopropylamino)butylamino]propyl}butane-1-sulfonamide trihydrochroride (2b, BsSPMG), were synthesized, and the effects of these polyamine derivatives on NMDA receptors were studied using voltage-clamp recordings of recombinant NMDA receptors expressed in Xenopus oocytes. Although spermine potentiates 153% and 310% of NMDA (NR1A/NR2B) receptors in the presence of saturated and unsaturated glycine, respectively, all the novel polyamine derivatives, TsHSPMG (1a), BsHSPMG (1b), TsSPMG (2a) and BsSPMG (2b), significantly inhibited NR1A/NR2B receptors in both conditions. The degree of NMDA receptor inhibition by TsHSPMG (1a) and BsHSPMG (1b) was stronger than that by TsSPMG (2a) and BsSPMG (2b).

  5. The role of N-methyl-D-aspartate receptors and nitric oxide in cochlear dopamine release.

    PubMed

    Halmos, G; Horváth, T; Polony, G; Fekete, A; Kittel, A; Vizi, E S; van der Laan, B F A M; Zelles, T; Lendvai, B

    2008-06-23

    Dopamine (DA) released from lateral olivocochlear (LOC) terminals may have a neuroprotective effect in the cochlea. To explore the role of N-methyl-d-aspartate (NMDA) receptors and nitric oxide (NO) in the modulation of a cochlear DA release, we measured the release of [3H]DA from isolated mouse cochlea in response to the application of NMDA. NMDA at 100 muM significantly increased the electrical-field stimulation-evoked and resting release of DA from the cochlea. The NO donor sodium nitroprusside enhanced the basal outflow of DA but failed to influence the evoked release. The administration of the nitric oxide synthase inhibitor N omega-nitro-L-arginine methyl ester (L-NAME) alone was ineffective, but it significantly inhibited the initial phase of the NMDA-induced elevation of DA outflow, which suggested the role of NO in the NMDA-induced DA release. The DA uptake inhibitor nomifensine increased the electrically evoked release of DA. Nomifensine failed to change the effect of NMDA on the resting or electrically-evoked DA release, which suggested that the uptake mechanism does not play a role in NMDA-evoked and NO-mediated DA release. In summary, we provide evidence that NO can modulate the release of DA from the cochlea following NMDA receptor activation, but does not affect the uptake of DA.

  6. Combination of behaviorally sub-effective doses of glutamate NMDA and dopamine D1 receptor antagonists impairs executive function.

    PubMed

    Desai, Sagar J; Allman, Brian L; Rajakumar, Nagalingam

    2017-04-14

    Impairment of executive function is a core feature of schizophrenia. Preclinical studies indicate that injections of either N-methyl d-aspartate (NMDA) or dopamine D 1 receptor blockers impair executive function. Despite the prevailing notion based on postmortem findings in schizophrenia that cortical areas have marked suppression of glutamate and dopamine, recent in vivo imaging studies suggest that abnormalities of these neurotransmitters in living patients may be quite subtle. Thus, we hypothesized that modest impairments in both glutamate and dopamine function can act synergistically to cause executive dysfunction. In the present study, we investigated the effect of combined administration of "behaviorally sub-effective" doses of NMDA and dopamine D 1 receptor antagonists on executive function. An operant conditioning-based set-shifting task was used to assess behavioral flexibility in rats that were systemically injected with NMDA and dopamine D 1 receptor antagonists individually or in combination prior to task performance. Separate injections of the NMDA receptor antagonist, MK-801, and the dopamine D 1 receptor antagonist, SCH 23390, at low doses did not impair set-shifting; however, the combined administration of these same behaviorally sub-effective doses of the antagonists significantly impaired the performance during set-shifting without affecting learning, retrieval of the memory of the initial rule, latency of responses or the number of omissions. The combined treatment also produced an increased number of perseverative errors. Our results indicate that NMDA and D 1 receptor blockade act synergistically to cause behavioral inflexibility, and as such, subtle abnormalities in glutamatergic and dopaminergic systems may act cooperatively to cause deficits in executive function. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. -HPLC determination of acidic d-amino acids and their N-methyl derivatives in biological tissues

    PubMed Central

    Tsesarskaia, Mara; Galindo, Erika; Szókán, Gyula; Fisher, George

    2015-01-01

    d-aspartate (d-Asp) and N-methyl-d-aspartate (NMDA) occur in the neuroendocrine systems of vertebrates and invertebrates where they play a role in hormone release and synthesis, neurotransmission, and memory and learning. N-methyl-d-glutamate (NMDG) has also been detected in marine bivalves. Several methods have been used to detect these amino acids, but they require pretreatment of tissue samples with o-phthaldialdehyde (OPA) to remove primary amino acids which interfere with the detection of NMDA and NMDG. We report here a one step derivatization procedure with the chiral reagent N-α-(5-fluoro-2,4-dinitrophenyl)-(d or l)-valine amide, FDNP-Val-NH2, a close analog of Marfey’s reagent but with better resolution and higher molar absorptivity. The diastereomers formed are separated by HPLC on an ODS-Hypersil column eluted with TFA/water – TFA/MeCN. UV absorption at 340 nm permits detection levels as low as 5–10 picomoles. D-Asp, NMDA and NMDG peaks are not obscured by other primary or secondary amino acids; hence pretreatment of tissues with OPA is not required. This method is highly reliable and fast (less than 40 minutes HPLC run). Using this method, we have detected D-Asp, NMDA and NMDG in several biological tissues (octopus brain, optical lobe, and bucchal mass; foot and mantle of the mollusk Scapharca broughtonii), confirming the results of other researchers. PMID:19277955

  8. Alkaloid fraction of Uncaria rhynchophylla protects against N-methyl-D-aspartate-induced apoptosis in rat hippocampal slices.

    PubMed

    Lee, Jongseok; Son, Dongwook; Lee, Pyeongjae; Kim, Sun-Yeou; Kim, Hocheol; Kim, Chang-Ju; Lim, Eunhee

    2003-09-04

    Uncaria rhynchophylla is a medicinal herb which has sedative and anticonvulsive effects and has been applied in the treatment of epilepsy in Oriental medicine. In this study, the effect of alkaloid fraction of U. rhynchophylla against N-methyl-D-aspartate (NMDA)-induced neuronal cell death was investigated. Pretreatment with an alkaloid fraction of U. rhynchophylla for 1 h decreased the degree of neuronal damage induced by NMDA exposure in cultured hippocampal slices and also inhibited NMDA-induced enhanced expressions of apoptosis-related genes such as c-jun, p53, and bax. In the present study, the alkaloid fraction of U. rhynchophylla was shown to have a protective property against NMDA-induced cytotoxicity by suppressing the NMDA-induced apoptosis in rat hippocampal slices.

  9. Protective effect of methanol extract of Uncaria rhynchophylla against excitotoxicity induced by N-methyl-D-aspartate in rat hippocampus.

    PubMed

    Lee, Jongseok; Son, Dongwook; Lee, Pyeongjae; Kim, Dae-Keun; Shin, Min-Chul; Jang, Mi-Hyeon; Kim, Chang-Ju; Kim, Yong-Sik; Kim, Sun-Yeou; Kim, Hocheol

    2003-05-01

    Uncaria rhynchophylla is a medicinal herb used for convulsive disorders in Oriental medicine. In this study, the effect of the methanol extract of Uncaria rhynchophylla against N-methyl-D-aspartate (NMDA)-induced excitotoxicity was investigated. Pretreatment with the extract of Uncaria rhynchopylla reduced the degree of neuronal damage induced by NMDA exposure in cultured hippocampal slices. In the patch clamp study, Uncaria rhynchophylla significantly inhibited NMDA receptor-activated ion current in acutely dissociated hippocampal CA1 neurons. These results indicate that Uncaria rhynchophylla offers protection against NMDA-induced neuronal injury and inhibitory action on NMDA receptor-mediated ion current may be a mechanism behind the neuroprotective effect of Uncaria rhynchophylla.

  10. Control of βAR- and N-methyl-D-aspartate (NMDA) Receptor-Dependent cAMP Dynamics in Hippocampal Neurons

    PubMed Central

    Chay, Andrew; Zamparo, Ilaria; Koschinski, Andreas; Zaccolo, Manuela; Blackwell, Kim T.

    2016-01-01

    Norepinephrine, a neuromodulator that activates β-adrenergic receptors (βARs), facilitates learning and memory as well as the induction of synaptic plasticity in the hippocampus. Several forms of long-term potentiation (LTP) at the Schaffer collateral CA1 synapse require stimulation of both βARs and N-methyl-D-aspartate receptors (NMDARs). To understand the mechanisms mediating the interactions between βAR and NMDAR signaling pathways, we combined FRET imaging of cAMP in hippocampal neuron cultures with spatial mechanistic modeling of signaling pathways in the CA1 pyramidal neuron. Previous work implied that cAMP is synergistically produced in the presence of the βAR agonist isoproterenol and intracellular calcium. In contrast, we show that when application of isoproterenol precedes application of NMDA by several minutes, as is typical of βAR-facilitated LTP experiments, the average amplitude of the cAMP response to NMDA is attenuated compared with the response to NMDA alone. Models simulations suggest that, although the negative feedback loop formed by cAMP, cAMP-dependent protein kinase (PKA), and type 4 phosphodiesterase may be involved in attenuating the cAMP response to NMDA, it is insufficient to explain the range of experimental observations. Instead, attenuation of the cAMP response requires mechanisms upstream of adenylyl cyclase. Our model demonstrates that Gs-to-Gi switching due to PKA phosphorylation of βARs as well as Gi inhibition of type 1 adenylyl cyclase may underlie the experimental observations. This suggests that signaling by β-adrenergic receptors depends on temporal pattern of stimulation, and that switching may represent a novel mechanism for recruiting kinases involved in synaptic plasticity and memory. PMID:26901880

  11. Differences in magnesium and calcium effects on N-methyl-D-aspartate- and quisqualate-induced decreases in extracellular sodium concentration in rat hippocampal slices.

    PubMed

    Köhr, G; Heinemann, U

    1988-01-01

    Decreases in extracellular sodium concentration [( Na+]o) and associated slow negative field potentials (fp's) were monitored with double barreled sodium sensitive/reference microelectrodes in area CA1 of rat hippocampal slices during iontophoretic application of the glutamate receptor agonists N-methyl-D-aspartate (NMDA) and quisqualate (quis). The effects of lowering [Ca2+]o on these signals were compared to those of lowering [Mg2+]o. Both NMDA- and quis-induced decreases in [Na+]o of up to 60 mM and in the fp's of up to 8 mV. Decreasing [Mg2+]o enhanced NMDA-induced signals, whereas quis-induced signals were unaffected. Lowering [Ca2+]o also enhanced NMDA signals, although somewhat less than lowering [Mg2+]o. This effect was still present, even when voltage dependent Na+ currents were blocked by 10(-7) tetrodotoxin. Interestingly, quis-induced signals could be enhanced in a low Ca2+ medium as well, but only when high quis concentrations were used. The results suggest that, during the sorts of large decreases of [Ca2+]o observed during seizure activity, activation of NMDA receptors is facilitated.

  12. Olanzapine, but not clozapine, increases glutamate release in the prefrontal cortex of freely moving mice by inhibiting D-aspartate oxidase activity

    PubMed Central

    Sacchi, Silvia; Novellis, Vito De; Paolone, Giovanna; Nuzzo, Tommaso; Iannotta, Monica; Belardo, Carmela; Squillace, Marta; Bolognesi, Paolo; Rosini, Elena; Motta, Zoraide; Frassineti, Martina; Bertolino, Alessandro; Pollegioni, Loredano; Morari, Michele; Maione, Sabatino; Errico, Francesco; Usiello, Alessandro

    2017-01-01

    D-aspartate levels in the brain are regulated by the catabolic enzyme D-aspartate oxidase (DDO). D-aspartate activates NMDA receptors, and influences brain connectivity and behaviors relevant to schizophrenia in animal models. In addition, recent evidence reported a significant reduction of D-aspartate levels in the post-mortem brain of schizophrenia-affected patients, associated to higher DDO activity. In the present work, microdialysis experiments in freely moving mice revealed that exogenously administered D-aspartate efficiently cross the blood brain barrier and stimulates L-glutamate efflux in the prefrontal cortex (PFC). Consistently, D-aspartate was able to evoke L-glutamate release in a preparation of cortical synaptosomes through presynaptic stimulation of NMDA, mGlu5 and AMPA/kainate receptors. In support of a potential therapeutic relevance of D-aspartate metabolism in schizophrenia, in vitro enzymatic assays revealed that the second-generation antipsychotic olanzapine, differently to clozapine, chlorpromazine, haloperidol, bupropion, fluoxetine and amitriptyline, inhibits the human DDO activity. In line with in vitro evidence, chronic systemic administration of olanzapine induces a significant extracellular release of D-aspartate and L-glutamate in the PFC of freely moving mice, which is suppressed in Ddo knockout animals. These results suggest that the second-generation antipsychotic olanzapine, through the inhibition of DDO activity, increases L-glutamate release in the PFC of treated mice. PMID:28393897

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    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.

  14. Inducible Nitric Oxide Inhibitors Block NMDA Antagonist-Stimulated Motoric Behaviors and Medial Prefrontal Cortical Glutamate Efflux

    PubMed Central

    Bergstrom, Hadley C.; Darvesh, Altaf S.; Berger, S. P.

    2015-01-01

    Nitric oxide (NO) plays a critical role in the motoric and glutamate releasing action of N-methyl-D-aspartate (NMDA)-antagonist stimulants. Earlier studies utilized neuronal nitric oxide synthase inhibitors (nNOS) for studying the neurobehavioral effects of non-competitive NMDA-antagonist stimulants such as dizocilpine (MK-801) and phencyclidine (PCP). This study explores the role of the inducible nitric oxide synthase inhibitors (iNOS) aminoguanidine (AG) and (-)-epigallocatechin-3-gallate (EGCG) in NMDA-antagonist induced motoric behavior and prefrontal cortical glutamate efflux. Adult male rats were administered a dose range of AG, EGCG, or vehicle prior to receiving NMDA antagonists MK-801, PCP, or a conventional psychostimulant (cocaine) and tested for motoric behavior in an open arena. Glutamate in the medial prefrontal cortex (mPFC) was measured using in vivo microdialysis after a combination of AG or EGCG prior to MK-801. Acute administration of AG or EGCG dose-dependently attenuated the locomotor and ataxic properties of MK-801 and PCP. Both AG and EGCG were unable to block the motoric effects of cocaine, indicating the acute pharmacologic action of AG and EGCG is specific to NMDA antagonism and not generalizable to all stimulant class drugs. AG and EGCG normalized MK-801-stimulated mPFC glutamate efflux. These data demonstrate that AG and EGCG attenuates NMDA antagonist-stimulated motoric behavior and cortical glutamate efflux. Our results suggest that EGCG-like polyphenol nutraceuticals (contained in “green tea” and chocolate) may be clinically useful in protecting against the adverse behavioral dissociative and cortical glutamate stimulating effects of NMDA antagonists. Medications that interfere with NMDA antagonists such as MK-801 and PCP have been proposed as treatments for schizophrenia. PMID:26696891

  15. Human T lymphocytes express N-methyl-D-aspartate receptors functionally active in controlling T cell activation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Miglio, Gianluca; Varsaldi, Federica; Lombardi, Grazia

    2005-12-30

    The aim of this study was to investigate the expression and the functional role of N-methyl-D-aspartate (NMDA) receptors in human T cells. RT-PCR analysis showed that human resting peripheral blood lymphocytes (PBL) and Jurkat T cells express genes encoding for both NR1 and NR2B subunits: phytohemagglutinin (PHA)-activated PBL also expresses both these genes and the NR2A and NR2D genes. Cytofluorimetric analysis showed that NR1 expression increases as a consequence of PHA (10 {mu}g/ml) treatment. D-(-)-2-Amino-5-phosphonopentanoic acid (D-AP5), and (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine [(+)-MK 801], competitive and non-competitive NMDA receptor antagonists, respectively, inhibited PHA-induced T cell proliferation, whereas they did not affect IL-2 (10more » U/ml)-induced proliferation of PHA blasts. These effects were due to the prevention of T cell activation (inhibition of cell aggregate formation and CD25 expression), but not to cell cycle arrest or death. These results demonstrate that human T lymphocytes express NMDA receptors, which are functionally active in controlling cell activation.« less

  16. GluN2B N-methyl-D-aspartate receptor and excitatory amino acid transporter 3 are upregulated in primary sensory neurons after 7 days of morphine administration in rats: implication for opiate-induced hyperalgesia.

    PubMed

    Gong, Kerui; Bhargava, Aditi; Jasmin, Luc

    2016-01-01

    The contribution of the peripheral nervous system to opiate-induced hyperalgesia (OIH) is not well understood. In this study, we determined the changes in excitability of primary sensory neurons after sustained morphine administration for 7 days. Changes in the expression of glutamate receptors and glutamate transporters after morphine administration were ascertained in dorsal root ganglions. Patch clamp recordings from intact dorsal root ganglions (ex vivo preparation) of morphine-treated rats showed increased excitability of small diameter (≤30 μm) neurons with respect to rheobase and membrane threshold, whereas the excitability of large diameter (>30 μm) neurons remained unchanged. Small diameter neurons also displayed increased responses to glutamate, which were mediated mainly by GluN2B containing N-methyl-D-aspartate (NMDA) receptors, and to a lesser degree by the neuronal excitatory amino acid transporter 3/excitatory amino acid carrier 1. Coadministration in vivo of the GluN2B selective antagonist Ro 25-6981 with morphine for 7 days prevented the appearance of OIH and increased morphine-induced analgesia. Administration of morphine for 7 days led to an increased expression of GluN2B and excitatory amino acid transporter 3/excitatory amino acid carrier 1, but not of the α-amino-3-hydroxy-5-methyl-4-isoxazole propionate, kainate, or group I metabotropic glutamate receptors, or of the vesicular glutamate transporter 2. These results suggest that peripheral glutamatergic neurotransmission contributes to OIH and that GluN2B subunit of NMDA receptors in the periphery may be a target for therapy.

  17. Protective effect of thalidomide against N-methyl-D-aspartate-induced retinal neurotoxicity.

    PubMed

    Takada, Kazuhide; Munemasa, Yasunari; Kuribayashi, Junko; Fujino, Hiromi; Kitaoka, Yasushi

    2011-10-01

    Thalidomide, an inhibitor of tumor necrosis factor-α (TNF-α) production, has been indicated to be useful for many inflammatory and oncogenic diseases. In the present study, we examined whether thalidomide (50 mg/kg/day, p.o.) has a protective effect against N-methyl-D-aspartate (NMDA)-induced retinal neurotoxicity in rats. A morphometric analysis showed that systemic administration of thalidomide protects neural cells in the ganglion cell layer (GCL) in a dose-dependent manner and significantly decreases the number of terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL)-positive cells in GCL and in the inner nuclear layer (INL). ELISA showed that thalidomide significantly suppressed the elevation of TNF-α 6 and 24 hr after an NMDA injection. Western blot analysis revealed a significant increase in nuclear factor-κB (NF-κB) p65 level in the retinas treated with NMDA at 24 hr after the injection, but not at 6 or 72 hr. Furthermore, an increase in p-JNK and p-p38 levels was also observed in the retina after NMDA injection. Thalidomide suppressed the increased expressions of NF-κB p65, p-JNK, and p-p38 after NMDA injection. Immunohistochemical analysis showed that thalidomide attenuated NF-κB p65 immunoreactivity in the GCL induced by NMDA treatment. In the NMDA-treated group, translocation of NF-κB p65 from the cytoplasm to the nucleus was detected in TUNEL-positive cells exposed to NMDA treatment. These results suggest new indications for thalidomide against neurodegenerative diseases. Copyright © 2011 Wiley-Liss, Inc.

  18. Implementation of a Fluorescence-Based Screening Assay Identifies Histamine H3 Receptor Antagonists Clobenpropit and Iodophenpropit as Subunit-Selective N-Methyl-d-Aspartate Receptor Antagonists

    PubMed Central

    Hansen, Kasper B.; Mullasseril, Praseeda; Dawit, Sara; Kurtkaya, Natalie L.; Yuan, Hongjie; Vance, Katie M.; Orr, Anna G.; Kvist, Trine; Ogden, Kevin K.; Le, Phuong; Vellano, Kimberly M.; Lewis, Iestyn; Kurtkaya, Serdar; Du, Yuhong; Qui, Min; Murphy, T. J.; Snyder, James P.; Bräuner-Osborne, Hans

    2010-01-01

    N-Methyl-d-aspartate (NMDA) receptors are ligand-gated ion channels that mediate a slow, Ca2+-permeable component of excitatory synaptic transmission in the central nervous system and play a pivotal role in synaptic plasticity, neuronal development, and several neurological diseases. We describe a fluorescence-based assay that measures NMDA receptor-mediated changes in intracellular calcium in a BHK-21 cell line stably expressing NMDA receptor NR2D with NR1 under the control of a tetracycline-inducible promoter (Tet-On). The assay selectively identifies allosteric modulators by using supramaximal concentrations of glutamate and glycine to minimize detection of competitive antagonists. The assay is validated by successfully identifying known noncompetitive, but not competitive NMDA receptor antagonists among 1800 screened compounds from two small focused libraries, including the commercially available library of pharmacologically active compounds. Hits from the primary screen are validated through a secondary screen that used two-electrode voltage-clamp recordings on recombinant NMDA receptors expressed in Xenopus laevis oocytes. This strategy identified several novel modulators of NMDA receptor function, including the histamine H3 receptor antagonists clobenpropit and iodophenpropit, as well as the vanilloid receptor transient receptor potential cation channel, subfamily V, member 1 (TRPV1) antagonist capsazepine. These compounds are noncompetitive antagonists and the histamine H3 receptor ligand showed submicromolar potency at NR1/NR2B NMDA receptors, which raises the possibility that compounds can be developed that act with high potency on both glutamate and histamine receptor systems simultaneously. Furthermore, it is possible that some actions attributed to histamine H3 receptor inhibition in vivo may also involve NMDA receptor antagonism. PMID:20197375

  19. (+)-3-( sup 123 I)Iodo-MK-801: Synthesis and characterization of binding to the N-methyl-D-aspartate receptor complex

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ransom, R.W.; Wai-si Eng; Burns, H.D.

    1990-01-01

    Synthetic methods have been established for preparing high specific activity (+)-3-({sup 123}I)Iodo-MK-801 in high radiochemical yield. The binding of the radiotracer to rat cortical membranes has been examine to assess its potential use as an in vivo imaging agent for the N-methyl-D-aspartate (NMDA) receptor-ion channel complex. Under the conditions of the assay, specific (+)-3-({sup 123}I)Iodo-MK-801 binding to membrane homogenates represented greater than 95% of the total binding. Several structurally distinct, noncompetitive NMDA receptor antagonists inhibited binding with potencies in accordance with their reported inhibitory activity at the receptor complex. The concentration of ({plus minus})-3-Iodo-MK-801 required to inhibit 50% of (+)-3-({supmore » 123}I)Iodo-MK-801 binding (IC{sub 50}) was 3.4 nM when using a low ionic strength assay buffer and 5.5 nM in a physiological buffer. In a thoroughly washed membrane preparation, (+)-3-({sup 123}I)Iodo-MK-801 binding was enhanced by L-glutamate and glycine at concentrations known to activate the NMDA receptor. The results indicate that (+)-3-({sup 123}I)Iodo-MK-801 specifically labels the NMDA receptor complex in rat brain membranes and the retention of high affinity under near physiological assay conditions suggests that it may be useful as a SPECT imaging agent for the receptor in vivo.« less

  20. Adolescent social defeat alters N-methyl-D-aspartic acid receptor expression and impairs fear learning in adulthood.

    PubMed

    Novick, Andrew M; Mears, Mackenzie; Forster, Gina L; Lei, Yanlin; Tejani-Butt, Shanaz M; Watt, Michael J

    2016-05-01

    Repeated social defeat of adolescent male rats results in adult mesocortical dopamine hypofunction, impaired working memory, and increased contextual anxiety-like behavior. Given the role of glutamate in dopamine regulation, cognition, and fear and anxiety, we investigated potential changes to N-methyl-D-aspartic acid (NMDA) receptors following adolescent social defeat. As both NMDA receptors and mesocortical dopamine are implicated in the expression and extinction of conditioned fear, a separate cohort of rats was challenged with a classical fear conditioning paradigm to investigate whether fear learning is altered by adolescent defeat. Quantitative autoradiography was used to measure 3H-MK-801 binding to NMDA receptors in regions of the medial prefrontal cortex, caudate putamen, nucleus accumbens, amygdala and hippocampus. Assessment of fear learning was achieved using an auditory fear conditioning paradigm, with freezing toward the auditory tone used as a measure of conditioned fear. Compared to controls, adolescent social defeat decreased adult NMDA receptor expression in the infralimbic region of the prefrontal cortex and central amygdala, while increasing expression in the CA3 region of the hippocampus. Previously defeated rats also displayed decreased conditioned freezing during the recall and first extinction periods, which may be related to the observed decreases and increases in NMDA receptors within the central amygdala and CA3, respectively. The alteration in NMDA receptors seen following adolescent social defeat suggests that dysfunction of glutamatergic systems, combined with mesocortical dopamine deficits, likely plays a role in the some of the long-term behavioral consequences of social stressors in adolescence seen in both preclinical and clinical studies. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Extended fear conditioning reveals a role for both N-methyl-D-aspartic acid and non-N-methyl-D-aspartic acid receptors in the amygdala in the acquisition of conditioned fear.

    PubMed

    Pistell, P J; Falls, W A

    2008-09-09

    Pavlovian conditioning is a useful tool for elucidating the neural mechanisms involved with learning and memory, especially in regard to the stimuli associated with aversive events. The amygdala has been repeatedly implicated as playing a significant role in the acquisition and expression of fear. If the amygdala is critical for the acquisition of fear, then it should contribute to this processes regardless of the parameters used to induce or evaluate conditioned fear. A series of experiments using reversible inactivation techniques evaluated the role of the amygdala in the acquisition of conditioned fear when training was conducted over several days in rats. Fear-potentiated startle was used to evaluate the acquisition of conditioned fear. Pretraining infusions of N-methyl-d-aspartic acid (NMDA) or non-NMDA receptor antagonists alone into the amygdala interfered with the acquisition of fear early in training, but not later. Pretraining infusions of a cocktail consisting of both an NMDA and non-NMDA antagonist interfered with the acquisition of conditioned fear across all days of training. Taken together these results suggest the amygdala may potentially be critical for the acquisition of conditioned fear regardless of the parameters utilized.

  2. TAAR1 Modulates Cortical Glutamate NMDA Receptor Function

    PubMed Central

    Espinoza, Stefano; Lignani, Gabriele; Caffino, Lucia; Maggi, Silvia; Sukhanov, Ilya; Leo, Damiana; Mus, Liudmila; Emanuele, Marco; Ronzitti, Giuseppe; Harmeier, Anja; Medrihan, Lucian; Sotnikova, Tatyana D; Chieregatti, Evelina; Hoener, Marius C; Benfenati, Fabio; Tucci, Valter; Fumagalli, Fabio; Gainetdinov, Raul R

    2015-01-01

    Trace Amine-Associated Receptor 1 (TAAR1) is a G protein-coupled receptor expressed in the mammalian brain and known to influence subcortical monoaminergic transmission. Monoamines, such as dopamine, also play an important role within the prefrontal cortex (PFC) circuitry, which is critically involved in high-o5rder cognitive processes. TAAR1-selective ligands have shown potential antipsychotic, antidepressant, and pro-cognitive effects in experimental animal models; however, it remains unclear whether TAAR1 can affect PFC-related processes and functions. In this study, we document a distinct pattern of expression of TAAR1 in the PFC, as well as altered subunit composition and deficient functionality of the glutamate N-methyl-D-aspartate (NMDA) receptors in the pyramidal neurons of layer V of PFC in mice lacking TAAR1. The dysregulated cortical glutamate transmission in TAAR1-KO mice was associated with aberrant behaviors in several tests, indicating a perseverative and impulsive phenotype of mutants. Conversely, pharmacological activation of TAAR1 with selective agonists reduced premature impulsive responses observed in the fixed-interval conditioning schedule in normal mice. Our study indicates that TAAR1 plays an important role in the modulation of NMDA receptor-mediated glutamate transmission in the PFC and related functions. Furthermore, these data suggest that the development of TAAR1-based drugs could provide a novel therapeutic approach for the treatment of disorders related to aberrant cortical functions. PMID:25749299

  3. Cutoff in Potency Implicates Alcohol Inhibition of N-Methyl-D-Aspartate Receptors in Alcohol Intoxication

    NASA Astrophysics Data System (ADS)

    Peoples, Robert W.; Weight, Forrest F.

    1995-03-01

    As the number of carbon atoms in an aliphatic n-alcohol is increased from one to five, intoxicating potency, lipid solubility, and membrane lipid disordering potency all increase in a similar exponential manner. However, the potency of aliphatic n-alcohols for producing intoxication reaches a maximum at six to eight carbon atoms and then decreases. The molecular basis of this "cutoff" effect is not understood, as it is not correlated with either the lipid solubility or the membrane disordering potency of the alcohols, which continue to increase exponentially. Since it has been suggested that inhibition of N-methyl-D-aspartate (NMDA) receptors by alcohols may play a role in alcohol intoxication, we investigated whether a series of aliphatic n-alcohols would exhibit a cutoff in potency for inhibition of NMDA receptors. We found that although potency for inhibition of NMDA receptors increased exponentially for alcohols with one to five carbon atoms, potency for inhibition of NMDA receptors reached a maximum at six to eight carbon atoms and then abruptly disappeared. This cutoff for alcohol inhibition of NMDA receptors is consistent with an interaction of the alcohols with a hydrophobic pocket on the receptor protein. In addition, the similarity of the cutoffs for alcohol inhibition of NMDA receptors and alcohol intoxication suggests that the cutoff for NMDA receptor inhibition may contribute to the cutoff for alcohol intoxication, which is consistent with an important role of NMDA receptors in alcohol intoxication.

  4. Inflammatory pain-induced signaling events following a conditional deletion of the N-methyl-D-aspartate receptor in spinal cord dorsal horn.

    PubMed

    Cheng, H T; Suzuki, M; Hegarty, D M; Xu, Q; Weyerbacher, A R; South, S M; Ohata, M; Inturrisi, C E

    2008-08-26

    The N-methyl-d-aspartate (NMDA) receptor in the spinal cord dorsal horn (SCDH) is one of the mechanisms involved in central sensitization during chronic pain. Previously, this laboratory created a spatio-temporal knockout (KO) of the N-methyl-d-aspartate receptor I (NR1) subunit in the mouse SCDH. The NR1 KO completely blocks NR1 gene and subsequent NMDA receptor expression and function in SCDH neurons. In the NR1 KO mice, the mechanical and cold allodynia induced at 24 h after complete Freund's adjuvant (CFA) was reduced. However, the protective effects of KO were transient and were not seen at 48 h after CFA. These observations suggest the presence of NMDA-independent pathways that contribute to CFA-induced pain. CFA induces the activation of several signaling cascades in the SCDH, including protein kinase C (PKC)gamma and extracellular signal-regulated kinases (ERK1/2). The phosphorylation of PKCgamma and ERK1/2 was inhibited in the SCDH of NR1 KO mice up to 48 h after CFA treatment, suggesting that these pathways are NMDA receptor-dependent. Interestingly, neuronal cyclooxygenase (COX) -2 expression and microglial p38 phosphorylation were induced in the SCDH of the NR1 KO at 48 h after CFA. Our findings provide evidence that inflammatory reactions are responsible for the recurrence of pain after NR1 KO in the SCDH.

  5. Effects of the noncompetitive N-methyl-d-aspartate receptor antagonists ketamine and MK-801 on pain-stimulated and pain-depressed behaviour in rats.

    PubMed

    Hillhouse, T M; Negus, S S

    2016-09-01

    Pain is a significant public health concern, and current pharmacological treatments have problematic side effects and limited effectiveness. N-methyl-d-aspartate (NMDA) glutamate receptor antagonists have emerged as one class of candidate treatments for pain because of the significant contribution of glutamate signalling in nociceptive processing. This study compared effects of the NMDA receptor antagonists ketamine and MK-801 in assays of pain-stimulated and pain-depressed behaviour in rats. The nonsteroidal anti-inflammatory drug ketoprofen was examined for comparison as a positive control. Intraperitoneal injection of dilute acid served as an acute visceral noxious stimulus to stimulate a stretching response or depress intracranial self-stimulation (ICSS) in male Sprague-Dawley rats. Ketamine (1.0-10.0 mg/kg) blocked acid-stimulated stretching but failed to block acid-induced depression of ICSS, whereas MK-801 (0.01-0.1 mg/kg) blocked both acid-stimulated stretching and acid-induced depression of ICSS. These doses of ketamine and MK-801 did not alter control ICSS in the absence of the noxious stimulus; however, higher doses of ketamine (10 mg/kg) and MK-801 (0.32 mg/kg) depressed all behaviour. Ketoprofen (1.0 mg/kg) blocked both acid-induced stimulation of stretching and depression of ICSS without altering control ICSS. These results support further consideration of NMDA receptor antagonists as analgesics; however, some NMDA receptor antagonists are more efficacious at attenuating pain-depressed behaviours. NMDA receptor antagonists produce dissociable effects on pain-depressed behaviour. Provides evidence that pain-depressed behaviours should be considered and evaluated when determining the antinociceptive effects of NMDA receptor antagonists. © 2016 European Pain Federation - EFIC®

  6. Effects of the noncompetitive N-methyl-D-aspartate receptor antagonists ketamine and MK-801 on pain-stimulated and pain-depressed behaviour in rats

    PubMed Central

    Hillhouse, T.M.; Negus, S.S.

    2017-01-01

    Background Pain is a significant public health concern, and current pharmacological treatments have problematic side effects and limited effectiveness. N-methyl-D-aspartate (NMDA) glutamate receptor antagonists have emerged as one class of candidate treatments for pain because of the significant contribution of glutamate signalling in nociceptive processing. Methods This study compared effects of the NMDA receptor antagonists ketamine and MK-801 in assays of pain-stimulated and pain-depressed behaviour in rats. The nonsteroidal anti-inflammatory drug ketoprofen was examined for comparison as a positive control. Intraperitoneal injection of dilute acid served as an acute visceral noxious stimulus to stimulate a stretching response or depress intracranial self-stimulation (ICSS) in male Sprague–Dawley rats. Results Ketamine (1.0–10.0 mg/kg) blocked acid-stimulated stretching but failed to block acid-induced depression of ICSS, whereas MK-801 (0.01–0.1 mg/kg) blocked both acid-stimulated stretching and acid-induced depression of ICSS. These doses of ketamine and MK-801 did not alter control ICSS in the absence of the noxious stimulus; however, higher doses of ketamine (10 mg/kg) and MK-801 (0.32 mg/kg) depressed all behaviour. Ketoprofen (1.0 mg/kg) blocked both acid-induced stimulation of stretching and depression of ICSS without altering control ICSS. Conclusion These results support further consideration of NMDA receptor antagonists as analgesics; however, some NMDA receptor antagonists are more efficacious at attenuating pain-depressed behaviours. What does this study add? NMDA receptor antagonists produce dissociable effects on pain-depressed behaviour. Provides evidence that pain-depressed behaviours should be considered and evaluated when determining the antinociceptive effects of NMDA receptor antagonists. PMID:26914635

  7. Implication of NMDA type glutamate receptors in neural regeneration and neoformation of synapses after excitotoxic injury in the guinea pig cochlea.

    PubMed

    d'Aldin, C G; Ruel, J; Assié, R; Pujol, R; Puel, J L

    1997-07-01

    In the adult mammalian cochlea, the ability of nerve fibres to regenerate has been observed following disruption of the organ of Corti by various means, or transsection of the cochlear nerve in the internal auditory meatus. Based upon the implication of glutamate as a neurotransmitter at synapses between sensory hair cells and terminal dendrites of the auditory nerve in the mammalian cochlea, we have developed, in a previous study, an in vivo model of neural regeneration and formation of synapses after the destruction of the afferent nerve endings by local application of the glutamate agonist alpha-amino-3-hydroxy-5-methyl-isoxazol-propionic acid (AMPA). In situ hybridization experiments performed during the re-innervation process revealed an overexpression of mRNA coding for NR1 subunit of N-methyl-D-aspartate (NMDA) receptors in the spiral ganglion neurons, suggesting that these receptors are implicated in neural regenerative processes. The present study has been designed to study the functional implication of NMDA receptors in the regrowth and synaptic repair of auditory dendrites in the guinea pig cochlea, by blocking the NMDA receptors during the period of normal functional recovery. In a first set of experiments, we recorded compound action potential after acute perilymphatic perfusion of cumulative doses (0.03-10mM) of DL 2-amino-5-phosphonovalerate (D-AP5), a NMDA antagonist, to determine the efficiency of the drug. In a second set of experiments, the auditory dendrites were destroyed by local application of the glutamate agonist AMPA. The blockage of NMDA by the antagonist D-AP5 applied with an osmotic micropump delayed the functional recovery and the regrowth of auditory dendrites. The findings of our study support the hypothesis that, in addition to acting as a fast transmitter, glutamate has a neurotrophic role via the activation of NMDA receptors.

  8. Development of N-Methyl-D-Aspartate Receptor Subunits in Avian Auditory Brainstem

    PubMed Central

    TANG, YE-ZHONG; CARR, CATHERINE E.

    2012-01-01

    N-methyl-D-aspartate (NMDA) receptor subunit-specific probes were used to characterize developmental changes in the distribution of excitatory amino acid receptors in the chicken’s auditory brainstem nuclei. Although NR1 subunit expression does not change greatly during the development of the cochlear nuclei in the chicken (Tang and Carr [2004] Hear. Res 191:79 – 89), there are significant developmental changes in NR2 subunit expression. We used in situ hybridization against NR1, NR2A, NR2B, NR2C, and NR2D to compare NR1 and NR2 expression during development. All five NMDA subunits were expressed in the auditory brainstem before embryonic day (E) 10, when electrical activity and synaptic responses appear in the nucleus magnocellularis (NM) and the nucleus laminaris (NL). At this time, the dominant form of the receptor appeared to contain NR1 and NR2B. NR2A appeared to replace NR2B by E14, a time that coincides with synaptic refinement and evoked auditory responses. NR2C did not change greatly during auditory development, whereas NR2D increased from E10 and remained at fairly high levels into adulthood. Thus changes in NMDA NR2 receptor subunits may contribute to the development of auditory brainstem responses in the chick. PMID:17366608

  9. N-methyl-d-aspartate (NMDA) receptor antibodies encephalitis mimicking an autistic regression.

    PubMed

    Hacohen, Yael; Wright, Sukhvir; Gadian, Jonathan; Vincent, Angela; Lim, Ming; Wassmer, Evangeline; Lin, Jean-Pierre

    2016-10-01

    Expressive dysphasia and mutism are common clinical features in children and adults with N-methyl-d-aspartate receptor antibodies (NMDAR-Ab) encephalitis, and are likely to result from NMDAR hypofunction. A prodromal loss of social and communication skills can typify that of an autistic regression, particularly when presenting under the age of 3 years. Here we describe two toddlers who presented with developmental regression, particularly of their social communication skills, mimicking an autistic regression, who were found to have NMDAR-Ab in the serum and cerebrospinal fluid. Although both patients had some other neurological features, they were subtle, which resulted in delayed diagnosis of NMDAR-Ab encephalitis. Importantly, immunotherapy was beneficial in both patients, with significant improvement of their language skills and behaviour. © 2016 Mac Keith Press.

  10. Anti-N-Methyl-D-Aspartate Receptor Encephalitis and Rasmussen-like Syndrome: An Association?

    PubMed

    Gurcharran, Kevin; Karkare, Shefali

    2017-01-01

    N-methyl-D-aspartate (NMDA) receptor encephalitis is an immune-mediated condition that has a broad spectrum of manifestations, including seizures, coma, psychosis, and focal neurological deficits. Although usually a diffuse process, unihemispheric involvement mimicking early stages of Rasmussen encephalitis can occur. Rasmussen's encephalitis is a unique syndrome characterized by progressive hemiplegia, drug-resistant focal epilepsy, cognitive decline, and hemispheric brain atrophy contralateral to the hemiplegia. We describe a two-year-old girl with progressive right weakness and epilepsia partialis continua, concerning for early Rasmussen's encephalitis, who tested positive for anti-NMDA receptor antibodies. She experienced complete clinical recovery after immunotherapy. Anti-NMDA receptor antibodies were absent at three weeks and again at one year after the first treatment of intravenous immunoglobulin. There are few reports of Rasmussen-like encephalitis in individuals with anti-NMDA receptor antibody positivity. Thus the clinical significance of this association is yet to be determined. In addition, several other antibodies have been documented in individuals with Rasmussen encephalitis. The lack of a consistently reported antibody in Rasmussen encephalitis patients and the temporary nature of the anti-NMDA receptor antibody in our patient raise the following question: Is the presence of anti-NMDA receptor antibodies the cause of the symptoms or secondary to the pathogenic process? Copyright © 2016 Elsevier Inc. All rights reserved.

  11. A comparison of N-methyl-D-aspartate-evoked release of adenosine and ( sup 3 H)norepinephrine from rat cortical slices

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hoehn, K.; Craig, C.G.; White, T.D.

    1990-10-01

    Tetrodotoxin reduced N-methyl-D-aspartate (NMDA)-evoked release of adenosine by 35% but virtually abolished (3H)norepinephrine release. Although (3H)norepinephrine release from rat cortical slices evoked by 500 microM NMDA was abolished by 1.2 mM Mg++, which produces a voltage-sensitive, uncompetitive block of NMDA-channels, adenosine release was increased in the presence of Mg++. Partial depolarization with 12 mM K+ relieved the Mg++ block of 500 microM NMDA-evoked (3H)norepinephrine release but did not affect adenosine release, indicating that a Mg++ requirement for the adenosine release process per se cannot account for this discrepancy. NMDA was 33 times more potent in releasing adenosine than (3H)norepinephrine. Atmore » submaximal concentrations of NMDA (10 and 20 microM), adenosine release was augmented in Mg+(+)-free medium. Although a high concentration of the uncompetitive NMDA antagonist MK-801 ((+)-5-methyl-10,11,dihydro-5H-dibenzo(a,d)cyclohepten-5-10-imine maleate) (3 microM) blocked NMDA-evoked release of (3H)norepinephrine and adenosine, a lower concentration (300 nM) decreased NMDA-evoked (3H)norepinephrine release by 66% without affecting adenosine release. These findings suggest that maximal adenosine release occurs when relatively few NMDA receptors are activated, raising the possibility that spare receptors exist for NMDA-evoked adenosine release. Rather than acting as a protectant against excessive NMDA excitation, released adenosine might provide an inhibitory threshold which must be overcome for NMDA-mediated neurotransmission to proceed.« less

  12. N-Methyl-d-Aspartate (NMDA) Receptor Blockade Prevents Neuronal Death Induced by Zika Virus Infection.

    PubMed

    Costa, Vivian V; Del Sarto, Juliana L; Rocha, Rebeca F; Silva, Flavia R; Doria, Juliana G; Olmo, Isabella G; Marques, Rafael E; Queiroz-Junior, Celso M; Foureaux, Giselle; Araújo, Julia Maria S; Cramer, Allysson; Real, Ana Luíza C V; Ribeiro, Lucas S; Sardi, Silvia I; Ferreira, Anderson J; Machado, Fabiana S; de Oliveira, Antônio C; Teixeira, Antônio L; Nakaya, Helder I; Souza, Danielle G; Ribeiro, Fabiola M; Teixeira, Mauro M

    2017-04-25

    Zika virus (ZIKV) infection is a global health emergency that causes significant neurodegeneration. Neurodegenerative processes may be exacerbated by N -methyl-d-aspartate receptor (NMDAR)-dependent neuronal excitoxicity. Here, we have exploited the hypothesis that ZIKV-induced neurodegeneration can be rescued by blocking NMDA overstimulation with memantine. Our results show that ZIKV actively replicates in primary neurons and that virus replication is directly associated with massive neuronal cell death. Interestingly, treatment with memantine or other NMDAR blockers, including dizocilpine (MK-801), agmatine sulfate, or ifenprodil, prevents neuronal death without interfering with the ability of ZIKV to replicate in these cells. Moreover, in vivo experiments demonstrate that therapeutic memantine treatment prevents the increase of intraocular pressure (IOP) induced by infection and massively reduces neurodegeneration and microgliosis in the brain of infected mice. Our results indicate that the blockade of NMDARs by memantine provides potent neuroprotective effects against ZIKV-induced neuronal damage, suggesting it could be a viable treatment for patients at risk for ZIKV infection-induced neurodegeneration. IMPORTANCE Zika virus (ZIKV) infection is a global health emergency associated with serious neurological complications, including microcephaly and Guillain-Barré syndrome. Infection of experimental animals with ZIKV causes significant neuronal damage and microgliosis. Treatment with drugs that block NMDARs prevented neuronal damage both in vitro and in vivo These results suggest that overactivation of NMDARs contributes significantly to the neuronal damage induced by ZIKV infection, and this is amenable to inhibition by drug treatment. Copyright © 2017 Costa et al.

  13. Effects of NMDA and non-NMDA ionotropic glutamate receptors in the medial preoptic area on body temperature in awake rats.

    PubMed

    Sengupta, Trina; Jaryal, Ashok Kumar; Mallick, Hruda Nanda

    2016-10-01

    Glutamate when microinjected at the medial preoptic area (mPOA) influences brain temperature (T br ) and body temperature (T b ) in rats. Glutamate and its various receptors are present at the mPOA. The aim of this study was to identify the contribution of each of the ionotropic glutamatergic receptors at the mPOA on changes in T br and T b in freely moving rats. Adult male Wistar rats (n=40) were implanted with bilateral guide cannula with indwelling styli above the mPOA. A telemetric transmitter was implanted at the peritoneum to record T b and locomotor activity (LMA). A precalibrated thermocouple wire implanted near the hypothalamus was used to assess T br . Specific agonist for each ionotropic glutamate receptor was microinjected into the mPOA and its effects on temperature and LMA were measured in the rats. The rats were also microinjected with the respective ionotropic receptor antagonists, 15min prior to the microinjection of each agonist. Amongst amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), N-methyl-d-aspartate (NMDA) and kainic acid, AMPA increased T b and LMA when injected at the mPOA. Specific antagonists for AMPA receptors was able to attenuate this increase (p<0.005). Pharmacological blockade of NMDA was able to lower T br only. Microinjection of kainic acid and its antagonist had no effect on the variables. The finding of the study suggests that activation of the AMPA receptors at the mPOA, leads to the rise in body temperature. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Mercury-induced toxicity of rat cortical neurons is mediated through N-Methyl-D-Aspartate receptors.

    PubMed

    Xu, Fenglian; Farkas, Svetlana; Kortbeek, Simone; Zhang, Fang-Xiong; Chen, Lina; Zamponi, Gerald W; Syed, Naweed I

    2012-09-14

    Mercury is a well-known neurotoxin implicated in a wide range of neurological or psychiatric disorders including autism spectrum disorders, Alzheimer's disease, Parkinson's disease, epilepsy, depression, mood disorders and tremor. Mercury-induced neuronal degeneration is thought to invoke glutamate-mediated excitotoxicity, however, the underlying mechanisms remain poorly understood. Here, we examine the effects of various mercury concentrations (including pathological levels present in human plasma or cerebrospinal fluid) on cultured, rat cortical neurons. We found that inorganic mercuric chloride (HgCl₂--at 0.025 to 25 μM) not only caused neuronal degeneration but also perturbed neuronal excitability. Whole-cell patch-clamp recordings of pyramidal neurons revealed that HgCl₂ not only enhanced the amplitude and frequency of synaptic, inward currents, but also increased spontaneous synaptic potentials followed by sustained membrane depolarization. HgCl₂ also triggered sustained, 2-5 fold rises in intracellular calcium concentration ([Ca²⁺]i). The observed increases in neuronal activity and [Ca²⁺]i were substantially reduced by the application of MK 801, a non-competitive antagonist of N-Methyl-D-Aspartate (NMDA) receptors. Importantly, our study further shows that a pre incubation or co-application of MK 801 prevents HgCl₂-induced reduction of cell viability and a disruption of β-tubulin. Collectively, our data show that HgCl₂-induced toxic effects on central neurons are triggered by an over-activation of NMDA receptors, leading to cytoskeleton instability.

  15. NMDA Receptor Modulators in the Treatment of Drug Addiction.

    PubMed

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

    2013-02-06

    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.

  16. N-(3-azidophenyl)-N-methyl-N'-([4-1H]- and [4-3H]-1-naphthyl)guanidine. A potent and selective ligand designed as a photoaffinity label for the phencyclidine site of the N-methyl-D-aspartate receptor.

    PubMed

    Gee, K R; Durant, G J; Holmes, D L; Magar, S S; Weber, E; Wong, S T; Keana, J F

    1993-01-01

    A novel radiolabeled photoaffinity ligand has been synthesized for the phencyclidine (PCP) site of the N-methyl-D-aspartate (NMDA) receptor. N-(3-Azidophenyl)-N-methyl-N'-([4-3H]-1-naphthyl)guanidine (13) was prepared with a specific activity of 25 Ci/mmol by diazotization of N-(3-aminophenyl)-N-methyl-N'-([4-3H]-1-naphthyl)guanidine (12) followed by treatment with sodium azide. Guanidine 12 was obtained by catalytic tritiation of N-(4-bromo-1-naphthyl)-N'-methyl-N'-(3-nitrophenyl)guanidine (11). The nontritiated analog 5 of 13 was prepared beginning with N-methyl-N'-1-naphthyl-N-(3-nitrophenyl)guanidine (9). The guanidines 9 and 11 were prepared in moderate yield by the aluminum chloride-catalyzed reaction of N-methyl-3-nitroaniline hydrochloride with 1-naphthylcyanamide and 4-bromo-1-naphthylcyanamide, respectively. Azide 5 showed high selectivity and affinity (IC50 = 100 nM vs [3H]MK801; 3000 nM vs [3H]ditolylguanidine) for the PCP site of the NMDA receptor in guinea pig brain homogenate. Photolabeling experiments with 13, however, failed to radiolabel a significant amount of receptor polypeptide.

  17. Neonatal (+)-methamphetamine exposure in rats alters adult locomotor responses to dopamine D1 and D2 agonists and to a glutamate NMDA receptor antagonist, but not to serotonin agonists

    PubMed Central

    Graham, Devon L.; Amos-Kroohs, Robyn M.; Braun, Amanda A.; Grace, Curtis E.; Schaefer, Tori L.; Skelton, Matthew R.; Williams, Michael T.; Vorhees, Charles V.

    2015-01-01

    Neonatal exposure to (+)-methamphetamine (Meth) results in long-term behavioural abnormalities but its developmental mechanisms are unknown. In a series of experiments, rats were treated from post-natal days (PD) 11–20 (stage that approximates human development from the second to third trimester) with Meth or saline and assessed using locomotor activity as the readout following pharmacological challenge doses with dopamine, serotonin and glutamate agonists or antagonists during adulthood. Exposure to Meth early in life resulted in an exaggerated adult locomotor hyperactivity response to the dopamine D1 agonist SKF-82958 at multiple doses, a high dose only under-response activating effect of the D2 agonist quinpirole, and an exaggerated under-response to the activating effect of the N-methyl-D-aspartic acid (NMDA) receptor antagonist, MK-801. No change in locomotor response was seen following challenge with the 5-HT releaser p-chloroamphetamine or the 5-HT2/3 receptor agonist, quipazine. These are the first data to show that PD 11-20 Meth exposure induces long-lasting alterations to dopamine D1, D2 and glutamate NMDA receptor function and may suggest how developmental Meth exposure leads to many of its long-term adverse effects. PMID:22391043

  18. Chronic neonatal N-methyl-D-aspartate receptor blockade induces learning deficits and transient hypoactivity in young rats.

    PubMed

    Latysheva, Nadejda V; Rayevsky, Kirill S

    2003-08-01

    A blockade of N-methyl-D-aspartate (NMDA)-type of glutamate receptor in rodents is believed to provide a pharmacological model of schizophrenia-related psychosis. Since neurodevelopmental abnormality, at least partly, could contribute to the pathogenesis of schizophrenia, the aim of this study was to recapitulate cognitive impairments accompanying this disorder in rats by a chronic neonatal treatment with a noncompetitive NMDA antagonist MK-801. Rat pups were treated with a low dose of MK-801 (0.05 mg/kg s.c.) chronically from early postnatal period (PD 7-49) known to be critical for glutamatergic system maturation. Locomotor activity in the "open-field" test, anxiety level in the elevated plus-maze test, and learning capacity in food rewarded spatial task were examined in young animals. Chronic MK-801 treatment produced a decrease of spontaneous motor and exploratory activity in 16- to 28-day-old rats. At the same time, a hyperlocomotion in response to acute administration of MK-801 was observed as well. Spatial learning of MK-801-treated rats was found to be negatively affected. Treated rats were able to respond to stress stimuli in the adequate manner but their anxiety level was found to be lower than in controls. Behavioral disturbances appeared to be temporary, and no such abnormalities could be detected at the age of 16 weeks. Thus, even mild chronic neonatal blockade of NMDA receptors may lead to a specific pattern of cognitive abnormalities presumably resulting from impairments of sensory information processing at the cortical-basal ganglia level.

  19. N-methyl-d-aspartate receptors, learning and memory: chronic intraventricular infusion of the NMDA receptor antagonist d-AP5 interacts directly with the neural mechanisms of spatial learning.

    PubMed

    Morris, R G M; Steele, R J; Bell, J E; Martin, S J

    2013-03-01

    Three experiments were conducted to contrast the hypothesis that hippocampal N-methyl-d-aspartate (NMDA) receptors participate directly in the mechanisms of hippocampus-dependent learning with an alternative view that apparent impairments of learning induced by NMDA receptor antagonists arise because of drug-induced neuropathological and/or sensorimotor disturbances. In experiment 1, rats given a chronic i.c.v. infusion of d-AP5 (30 mm) at 0.5 μL/h were selectively impaired, relative to aCSF-infused animals, in place but not cued navigation learning when they were trained during the 14-day drug infusion period, but were unimpaired on both tasks if trained 11 days after the minipumps were exhausted. d-AP5 caused sensorimotor disturbances in the spatial task, but these gradually worsened as the animals failed to learn. Histological assessment of potential neuropathological changes revealed no abnormalities in d-AP5-treated rats whether killed during or after chronic drug infusion. In experiment 2, a deficit in spatial learning was also apparent in d-AP5-treated rats trained on a spatial reference memory task involving two identical but visible platforms, a task chosen and shown to minimise sensorimotor disturbances. HPLC was used to identify the presence of d-AP5 in selected brain areas. In Experiment 3, rats treated with d-AP5 showed a delay-dependent deficit in spatial memory in the delayed matching-to-place protocol for the water maze. These data are discussed with respect to the learning mechanism and sensorimotor accounts of the impact of NMDA receptor antagonists on brain function. We argue that NMDA receptor mechanisms participate directly in spatial learning. © 2013 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

  20. Vesicular glutamate release from central axons contributes to myelin damage.

    PubMed

    Doyle, Sean; Hansen, Daniel Bloch; Vella, Jasmine; Bond, Peter; Harper, Glenn; Zammit, Christian; Valentino, Mario; Fern, Robert

    2018-03-12

    The axon myelin sheath is prone to injury associated with N-methyl-D-aspartate (NMDA)-type glutamate receptor activation but the source of glutamate in this context is unknown. Myelin damage results in permanent action potential loss and severe functional deficit in the white matter of the CNS, for example in ischemic stroke. Here, we show that in rats and mice, ischemic conditions trigger activation of myelinic NMDA receptors incorporating GluN2C/D subunits following release of axonal vesicular glutamate into the peri-axonal space under the myelin sheath. Glial sources of glutamate such as reverse transport did not contribute significantly to this phenomenon. We demonstrate selective myelin uptake and retention of a GluN2C/D NMDA receptor negative allosteric modulator that shields myelin from ischemic injury. The findings potentially support a rational approach toward a low-impact prophylactic therapy to protect patients at risk of stroke and other forms of excitotoxic injury.

  1. Involvement of glutamatergic N-methyl-d-aspartate receptors in the expression of increased head-dipping behaviors in the hole-board tests of olfactory bulbectomized mice.

    PubMed

    Hirose, Noritaka; Saitoh, Akiyoshi; Kamei, Junzo

    2016-10-01

    Olfactory bulbectomized (OB) mice produce agitated anxiety-like behaviors in the hole-board test, which was expressed by an increase in head-dipping counts and a decrease in head-dipping latencies. However, the associated mechanisms remain unclear. In the present study, MK-801 (10, 100μg/kg), a selective N-methyl-d-aspartate (NMDA) receptor antagonist, significantly and dose-dependently suppressed the increased head-dipping behaviors in OB mice, without affecting sham mice. Similar results were obtained with another selective NMDA receptor antagonist D-AP5 treatment in OB mice. On the other hand, muscimol, a selective aminobutyric acid type A (GABAA) receptor agonist produced no effects on these hyperemotional behaviors in OB mice at a dose (100μg/kg) that produced anxiolytic-like effects in sham mice. Interestingly, glutamine contents and glutamine/glutamate ratios were significantly increased in the amygdala and frontal cortex of OB mice compared to sham mice. Based on these results, we concluded that the glutamatergic NMDA receptors are involved in the expression of increased head-dipping behaviors in the hole-board tests of OB mice. Accordingly, the changes in glutamatergic transmission in frontal cortex and amygdala may play important roles in the expression of these abnormal behaviors in OB mice. Copyright © 2016. Published by Elsevier B.V.

  2. Ionotropic glutamate receptors activate cell signaling in response to glutamate in Schwann cells.

    PubMed

    Campana, Wendy M; Mantuano, Elisabetta; Azmoon, Pardis; Henry, Kenneth; Banki, Michael A; Kim, John H; Pizzo, Donald P; Gonias, Steven L

    2017-04-01

    In the peripheral nervous system, Schwann cells (SCs) demonstrate surveillance activity, detecting injury and undergoing trans -differentiation to support repair. SC receptors that detect peripheral nervous system injury remain incompletely understood. We used RT-PCR to profile ionotropic glutamate receptor expression in cultured SCs. We identified subunits required for assembly of N -methyl-d-aspartic acid (NMDA) receptors (NMDA-Rs), α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors, and kainate receptors. Treatment of SCs with 40-100 µM glutamate or with 0.5-1.0 µM NMDA robustly activated Akt and ERK1/2. The response was transient and bimodal; glutamate concentrations that exceeded 250 µM failed to activate cell signaling. Phosphoprotein profiling identified diverse phosphorylated proteins in glutamate-treated SCs in addition to ERK1/2 and Akt, including p70 S6-kinase, glycogen synthase kinase-3, ribosomal S6 kinase, c-Jun, and cAMP response element binding protein. Activation of SC signaling by glutamate was blocked by EGTA and dizocilpine and by silencing expression of the NMDA-R NR1 subunit. Phosphoinositide 3-kinase/PI3K functioned as an essential upstream activator of Akt and ERK1/2 in glutamate-treated SCs. When glutamate or NMDA was injected directly into crush-injured rat sciatic nerves, ERK1/2 phosphorylation was observed in myelinated and nonmyelinating SCs. Glutamate promoted SC migration by a pathway that required PI3K and ERK1/2. These results identified ionotropic glutamate receptors and NMDA-Rs, specifically, as potentially important cell signaling receptors in SCs.-Campana, W. M., Mantuano, E., Azmoon, P., Henry, K., Banki, M. A., Kim, J. H., Pizzo, D. P., Gonias, S. L. Ionotropic glutamate receptors activate cell signaling in response to glutamate in Schwann cells. © FASEB.

  3. Neuroprotective Effect of Tauroursodeoxycholic Acid on N-Methyl-D-Aspartate-Induced Retinal Ganglion Cell Degeneration

    PubMed Central

    Fernández-Sánchez, Laura; Rondón, Netxibeth; Esquiva, Gema; Germain, Francisco; de la Villa, Pedro; Cuenca, Nicolás

    2015-01-01

    Retinal ganglion cell degeneration underlies the pathophysiology of diseases affecting the retina and optic nerve. Several studies have previously evidenced the anti-apoptotic properties of the bile constituent, tauroursodeoxycholic acid, in diverse models of photoreceptor degeneration. The aim of this study was to investigate the effects of systemic administration of tauroursodeoxycholic acid on N-methyl-D-aspartate (NMDA)-induced damage in the rat retina using a functional and morphological approach. Tauroursodeoxycholic acid was administered intraperitoneally before and after intravitreal injection of NMDA. Three days after insult, full-field electroretinograms showed reductions in the amplitudes of the positive and negative-scotopic threshold responses, scotopic a- and b-waves and oscillatory potentials. Quantitative morphological evaluation of whole-mount retinas demonstrated a reduction in the density of retinal ganglion cells. Systemic administration of tauroursodeoxycholic acid attenuated the functional impairment induced by NMDA, which correlated with a higher retinal ganglion cell density. Our findings sustain the efficacy of tauroursodeoxycholic acid administration in vivo, suggesting it would be a good candidate for the pharmacological treatment of degenerative diseases coursing with retinal ganglion cell loss. PMID:26379056

  4. Effects of volatile solvents on recombinant N-methyl-D-aspartate receptors expressed in Xenopus oocytes

    PubMed Central

    Cruz, Silvia L; Balster, Robert L; Woodward, John J

    2000-01-01

    We have previously shown that toluene dose-dependently inhibits recombinant N-methyl-D-aspartate (NMDA) receptors at micromolar concentrations. This inhibition was rapid, almost complete and reversible. The NR1/2B combination was the most sensitive receptor subtype tested with an IC50 value for toluene of 0.17 mM. We now report on the effects of other commonly abused solvents (benzene, m-xylene, ethylbenzene, propylbenzene, 1,1,1-trichlorethane (TCE) and those of a convulsive solvent, 2,2,2-trifluoroethyl ether (flurothyl), on NMDA-induced currents measured in Xenopus oocytes expressing NR1/2A or NR1/2B receptor subtypes. All of the alkylbenzenes and TCE produced a reversible inhibition of NMDA-induced currents that was dose- and subunit-dependent. The NR1/2B receptor subtype was several times more sensitive to these compounds than the NR1/2A subtype. The convulsant solvent flurothyl had no effect on NMDA responses in oocytes but potently inhibited ion flux through recombinant GABA receptors expressed in oocytes. Overall, these results suggest that abused solvents display pharmacological selectivity and that NR1/2B NMDA receptors may be an important target for the actions of these compounds on the brain. PMID:11090101

  5. Kynurenic acid analogues with improved affinity and selectivity for the glycine site on the N-methyl-D-aspartate receptor from rat brain.

    PubMed

    Foster, A C; Kemp, J A; Leeson, P D; Grimwood, S; Donald, A E; Marshall, G R; Priestley, T; Smith, J D; Carling, R W

    1992-05-01

    The glycine site on the N-methyl-D-aspartate (NMDA) subtype of receptors for the excitatory neurotransmitter glutamate is a potential target for the development of neuroprotective drugs. We report here two chemical series of glycine site antagonists derived from kynurenic acid (KYNA), with greatly improved potency and selectivity. Disubstitution with chlorine or bromine in the 5- and 7-positions of KYNA increased affinity for [3H]glycine binding sites in rat cortex/hippocampus P2 membranes, with a parallel increase of potency for antagonism of NMDA-evoked responses in the rat cortical wedge preparation. The optimal compound was 5-I,7-Cl-KYNA, with an IC50 for [3H]glycine binding of 29 nM and an apparent Kb in the cortical wedge preparation of 0.41 microM. Reduction of the right-hand ring of 5,7-diCl-KYNA reduced affinity by 10-fold, but this was restored by substitution in the 4-position with the trans-phenylamide and further improved in the trans-benzylamide. The optimal compound was the transphenylurea (L-689,560), with an IC50 of 7.4 nM and an apparent Kb of 0.13 microM. Both series of compounds displayed a high degree of selectivity for the glycine site, having IC50 values of greater than 10 microM versus radioligand binding to the glutamate recognition sites of NMDA, alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA), and kainate receptors and the strychnine-sensitive glycine receptor. Selectivity versus AMPA receptor-mediated responses was also apparent in the rat cortical wedge and in patch-clamp recordings of cortical neurons in culture. Experiments using [3H]dizocilpine (MK-801) binding indicated that 5,7-diBr-KYNA, 5,7-diCl-KYNA, 5-I,7-Cl-KYNA, and L-689,560 all behaved as full antagonists and were competitive with glycine. Patch-clamp recordings of cortical neurons in culture also indicated that NMDA-induced currents were antagonized by competition for the glycine site, and gave no evidence for partial agonist activity. pKi values for 5,7-di

  6. Spinal N-methyl-D-aspartate receptors and nociception-evoked release of primary afferent substance P.

    PubMed

    Nazarian, A; Gu, G; Gracias, N G; Wilkinson, K; Hua, X Y; Vasko, M R; Yaksh, T L

    2008-03-03

    Dorsal horn N-methyl-D-aspartate (NMDA) receptors contribute significantly to spinal nociceptive processing through an effect postsynaptic to non-primary glutamatergic axons, and perhaps presynaptic to the primary afferent terminals. The present study sought to examine the regulatory effects of NMDA receptors on primary afferent release of substance P (SP), as measured by neurokinin 1 receptor (NK1r) internalization in the spinal dorsal horn of rats. The effects of intrathecal NMDA alone or in combination with D-serine (a glycine site agonist) were initially examined on basal levels of NK1r internalization. NMDA alone or when co-administered with D-serine failed to induce NK1r internalization, whereas activation of spinal TRPV1 receptors by capsaicin resulted in a notable NK1r internalization. To determine whether NMDA receptor activation could potentiate NK1r internalization or pain behavior induced by a peripheral noxious stimulus, intrathecal NMDA was given prior to an intraplantar injection of formalin. NMDA did not alter the formalin-induced NK1r internalization nor did it enhance the formalin paw flinching behavior. To further characterize the effects of presynaptic NMDA receptors, the NMDA antagonists DL-2-amino-5-phosphonopentanoic acid (AP-5) and MK-801 were intrathecally administered to assess their regulatory effects on formalin-induced NK1r internalization and pain behavior. AP-5 had no effect on formalin-induced NK1r internalization, whereas MK-801 produced only a modest reduction. Both antagonists, however, reduced the formalin paw flinching behavior. In subsequent in vitro experiments, perfusion of NMDA in spinal cord slice preparations did not evoke basal release of SP or calcitonin gene-related peptide (CGRP). Likewise, perfusion of NMDA did not enhance capsaicin-evoked release of the two peptides. These results suggest that presynaptic NMDA receptors in the spinal cord play little if any role on the primary afferent release of SP.

  7. Specific Roles of NMDA Receptor Subunits in Mental Disorders.

    PubMed

    Yamamoto, H; Hagino, Y; Kasai, S; Ikeda, K

    2015-01-01

    N-methyl-D-aspartate (NMDA) receptor plays important roles in learning and memory. NMDA receptors are a tetramer that consists of two glycine-binding subunits GluN1, two glutamate-binding subunits (i.e., GluN2A, GluN2B, GluN2C, and GluN2D), a combination of a GluN2 subunit and glycine-binding GluN3 subunit (i.e., GluN3A or GluN3B), or two GluN3 subunits. Recent studies revealed that the specific expression and distribution of each subunit are deeply involved in neural excitability, plasticity, and synaptic deficits. The present article summarizes reports on the dysfunction of NMDA receptors and responsible subunits in various neurological and psychiatric disorders, including schizophrenia, autoimmune-induced glutamatergic receptor dysfunction, mood disorders, and autism. A key role for the GluN2D subunit in NMDA receptor antagonist-induced psychosis has been recently revealed.

  8. Targeting of glycine site on NMDA receptor as a possible new strategy for autism treatment.

    PubMed

    Ghanizadeh, Ahmad

    2011-05-01

    The exact pathophysiology of the neurodevelopment disorder of autism is not clear and there is not any curative approach for it. There is only one FDA-approved medication for its management. Therefore, providing of novel treatments is highly required. The hypofunction of GABAergic system and glutamate toxicity are generally believed to have a causal role for autism. The antagonist of the N-methyl-D-aspartic acid (NMDA) glutamate receptor improves autism. Glycine is required for the activation of NMDA receptor. The antagonist of glycine site decreases NMDA receptor conductance. It is hypothesis that glycine site antagonists can be tested as a new strategy for the management of autism.

  9. Initial clinical presentation of young children with N-methyl-d-aspartate receptor encephalitis.

    PubMed

    Favier, Marion; Joubert, Bastien; Picard, Géraldine; Rogemond, Véronique; Thomas, Laure; Rheims, Sylvain; Bailhache, Marion; Villega, Frédéric; Pédespan, Jean-Michel; Berzero, Giulia; Psimaras, Dimitri; Antoine, Jean-Christophe; Desestret, Virginie; Honnorat, Jérôme

    2018-05-01

    Autoimmune encephalitis with anti-N-methyl-d-aspartate receptor autoantibodies (NMDA-R-Abs) is a recently described disease affecting adult and pediatric patients. Symptoms of the disease are now perfectly described in the adult population but the clinical presentation is less known in young children. The aim of the present study was to describe the clinical presentation and the specificities of symptoms presented by young children with NMDA-R-Abs encephalitis to improve diagnosis of this disease, and to compare these to a series of previously published female adult patients. Fifty cases of children younger than twelve years of age diagnosed with NMDA-R-Abs encephalitis between January 1, 2007 and December 31, 2016 (27 females and 23 males) were retrospectively studied. The first neurological symptoms observed in young children with NMDA-R-Abs encephalitis were characterized by seizure (72%), especially focal seizure (42%), within a median of 15 days before other encephalitis symptoms; other patients mostly had behavioral disorders (26%). The seizures were frequently difficult to diagnose because of the transient unilateral dystonic or tonic posturing presentation or sudden unilateral pain in the absence of clonic movements. A post-ictal motor deficit was also frequently observed. This clinical presentation is different from that observed in adult females with NMDA-R-Abs encephalitis who initially present mainly psychiatric disorders (67%) or cognitive impairment (19%), and less frequently seizures (14%). The diagnosis of NMDA-R-Abs encephalitis should be systematically considered in young children of both sexes who present neurological symptoms suggesting recent seizures (focal or generalized) without obvious other etiology. Copyright © 2017 European Paediatric Neurology Society. Published by Elsevier Ltd. All rights reserved.

  10. 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.

  11. Does anesthetic additivity imply a similar molecular mechanism of anesthetic action at N-methyl-D-aspartate receptors?

    PubMed

    Brosnan, Robert J; Pham, Trung L

    2011-03-01

    Isoflurane and carbon dioxide (CO(2)) negatively modulate N-methyl-d-aspartate (NMDA) receptors, but via different mechanisms. Isoflurane is a competitive antagonist at the NMDA receptor glycine binding site, whereas CO(2) inhibits NMDA receptor current through extracellular acidification. Isoflurane and CO(2) exhibit additive minimum alveolar concentration effects in rats, but we hypothesized that they would not additively inhibit NMDA receptor currents in vitro because they act at different molecular sites. NMDA receptors were expressed in frog oocytes and studied using 2-electrode voltage clamp techniques. A glycine concentration response for NMDA was measured in the presence and absence of CO(2). Concentration-response curves for isoflurane, H(+), CO(2), and ketamine as a function of NMDA inhibition were measured, and a Hill equation was used to calculate the EC(50) for each compound. Binary drug combinations containing ½ EC(50) were additive if NMDA current inhibition was not statistically different from 50%. The ½ EC(50) binary drug combinations decreased the percentage baseline NMDA receptor current as follows (mean ± SD, n = 5 to 6 oocytes each): CO(2)+ H(+) (51% ± 5%), CO(2 )+ isoflurane (54% ± 5%), H(+) + isoflurane (51% ± 3%), CO(2)+ ketamine (67% ± 8%), and H(+) + ketamine (64% ± 2%). In contrast to our hypothesis, NMDA receptor inhibition by CO(2) and isoflurane is additive. Possibly, CO(2) acidification modulates a pH-sensitive loop on the NMDA receptor that in turn alters glycine binding affinity on the GluN1 subunit. However, ketamine plus either CO(2) or H(+) synergistically inhibits NMDA receptor currents. Drugs acting via different mechanisms can thus exhibit additive or synergistic receptor effects. Additivity may not robustly indicate commonality between molecular anesthetic mechanisms.

  12. Electroconvulsive Therapy in Anti-N-Methyl-D-Aspartate Receptor Encephalitis: A Case Report and Review of the Literature.

    PubMed

    Coffey, M Justin; Cooper, Joseph J

    2016-12-01

    There is a growing scientific literature describing the neuropsychiatric symptoms of anti-N-methyl-D-aspartate (NMDA) receptor encephalitis, including the use of electroconvulsive therapy (ECT) to treat those symptoms. We sought to consolidate this literature into a review that highlights its relevance to ECT practitioners. We performed a PubMed search using the terms electroconvulsive therapy and encephalitis, autoimmune encephalitis, or anti-NMDA receptor encephalitis. We reviewed all relevant studies in detail, cross-referenced all bibliographies, and collected key clinical information related to the practice of ECT. We identified 6 studies offering patient-level descriptions of the use of ECT in patients with anti-NMDA receptor encephalitis. In all cases ECT was used to target symptoms of catatonia. Electroconvulsive therapy was delivered safely and effectively irrespective of the timing of diagnosis, tumor removal, or immunotherapy. There are no controlled data on the use of ECT in anti-NMDA receptor encephalitis. Further investigation is needed to determine whether ECT has a disease-modifying effect on this form of autoimmune encephalitis.

  13. Rapamycin prevents N-methyl-D-aspartate-induced retinal damage through an ERK-dependent mechanism in rats.

    PubMed

    Ichikawa, Atsuko; Nakahara, Tsutomu; Kurauchi, Yuki; Mori, Asami; Sakamoto, Kenji; Ishii, Kunio

    2014-06-01

    Recent studies have demonstrated that inhibition of the mammalian target of rapamycin (mTOR) protects against neuronal injury, but the mechanisms underlying this protection are not fully understood. The present study investigates whether rapamycin, an inhibitor of the mTOR pathway, protects against N-methyl-D-aspartate (NMDA)-induced retinal neurotoxicity and whether the extracellular signal-regulated kinase (ERK) pathway contributes to this protective effect in rats. Significant cell loss in the ganglion cell layer and a reduction in thickness of the inner plexiform layer were observed 7 days after a single intravitreal injection of NMDA (200 nmol/eye). These NMDA-induced morphological changes were significantly reduced by rapamycin (20 nmol/eye). The number of terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling-positive apoptotic cells had increased 6 hr after NMDA injection, an effect that was significantly attenuated by rapamycin. The ERK inhibitor U0126 (1 nmol/eye) almost completely abolished rapamycin's inhibition of NMDA-induced apoptosis. Immunohistochemical studies showed that NMDA caused a time-dependent increase in levels of the phosphorylated form of the ribosomal protein S6 (pS6), a downstream indicator of mTOR activity. The increased pS6 levels were markedly decreased by rapamycin. Both NMDA and rapamycin increased the level of phosphorylated ERK (pERK) in Müller cells, and coinjection of both agents further increased pERK levels. These results suggest that rapamycin has a neuroprotective effect against NMDA-induced retinal neurotoxicity and that this effect could be patially mediated by activation of the ERK pathway in retinal Müller cells. Copyright © 2014 Wiley Periodicals, Inc.

  14. Control of Appetite and Food Preference by NMDA Receptor and Its Co-Agonist d-Serine

    PubMed Central

    Sasaki, Tsutomu; Matsui, Sho; Kitamura, Tadahiro

    2016-01-01

    Obesity causes a significant negative impact on health of human beings world-wide. The main reason for weight gain, which eventually leads to obesity, is excessive ingestion of energy above the body’s homeostatic needs. Therefore, the elucidation of detailed mechanisms for appetite control is necessary to prevent and treat obesity. N-methyl-d-aspartate (NMDA) receptor is a post-synaptic glutamate receptor and is important for excitatory neurotransmission. It is expressed throughout the nervous system, and is important for long-term potentiation. It requires both ligand (glutamate) and co-agonist (d-serine or glycine) for efficient opening of the channel to allow calcium influx. d-serine is contained in fermented foods and marine invertebrates, and brain d-serine level is maintained by synthesis in vivo and supply from food and gut microbiota. Although the NMDA receptor has been reported to take part in the central regulation of appetite, the role of d-serine had not been addressed. We recently reported that exogenous d-serine administration can suppress appetite and alter food preference. In this review, we will discuss how NMDA receptor and its co-agonist d-seine participate in the control of appetite and food preference, and elaborate on how this system could possibly be manipulated to suppress obesity. PMID:27399680

  15. H-Ras Modulates N-Methyl-d-aspartate Receptor Function via Inhibition of Src Tyrosine Kinase Activity*

    PubMed Central

    Thornton, Claire; Yaka, Rami; Dinh, Son; Ron, Dorit

    2005-01-01

    Tyrosine phosphorylation of the NR2A and NR2B subunits of the N-methyl-d-aspartate (NMDA) receptor by Src protein-tyrosine kinases modulates receptor channel activity and is necessary for the induction of long term potentiation (LTP). Deletion of H-Ras increases both NR2 tyrosine phosphorylation and NMDA receptor-mediated hippocampal LTP. Here we investigated whether H-Ras regulates phosphorylation and function of the NMDA receptor via Src family protein-tyrosine kinases. We identified Src as a novel H-Ras binding partner. H-Ras bound to Src but not Fyn both in vitro and in brain via the Src kinase domain. Cotransfection of H-Ras and Src inhibited Src activity and decreased NR2A tyrosine phosphorylation. Treatment of rat brain slices with Tat-H-Ras depleted NR2A from the synaptic membrane, decreased endogenous Src activity and NR2A phosphorylation, and decreased the magnitude of hip-pocampal LTP. No change was observed for NR2B. We suggest that H-Ras negatively regulates Src phosphorylation of NR2A and retention of NR2A into the synaptic membrane leading to inhibition of NMDA receptor function. This mechanism is specific for Src and NR2A and has implications for studies in which regulation of NMDA receptor-mediated LTP is important, such as synaptic plasticity, learning, and memory and addiction. PMID:12695509

  16. Excitotoxicity in the Lung: N-Methyl-D-Aspartate-Induced, Nitric Oxide-Dependent, Pulmonary Edema is Attenuated by Vasoactive Intestinal Peptide and by Inhibitors of Poly(ADP-Ribose) Polymerase

    NASA Astrophysics Data System (ADS)

    Said, Sami I.; Berisha, Hasan I.; Pakbaz, Hedayatollah

    1996-05-01

    Excitatory amino acid toxicity, resulting from overactivation of N-methyl-D-aspartate (NMDA) glutamate receptors, is a major mechanism of neuronal cell death in acute and chronic neurological diseases. We have investigated whether excitotoxicity may occur in peripheral organs, causing tissue injury, and report that NMDA receptor activation in perfused, ventilated rat lungs triggered acute injury, marked by increased pressures needed to ventilate and perfuse the lung, and by high-permeability edema. The injury was prevented by competitive NMDA receptor antagonists or by channel-blocker MK-801, and was reduced in the presence of Mg2+. As with NMDA toxicity to central neurons, the lung injury was nitric oxide (NO) dependent: it required L-arginine, was associated with increased production of NO, and was attenuated by either of two NO synthase inhibitors. The neuropeptide vasoactive intestinal peptide and inhibitors of poly(ADP-ribose) polymerase also prevented this injury, but without inhibiting NO synthesis, both acting by inhibiting a toxic action of NO that is critical to tissue injury. The findings indicate that: (i) NMDA receptors exist in the lung (and probably elsewhere outside the central nervous system), (ii) excessive activation of these receptors may provoke acute edematous lung injury as seen in the ``adult respiratory distress syndrome,'' and (iii) this injury can be modulated by blockade of one of three critical steps: NMDA receptor binding, inhibition of NO synthesis, or activation of poly(ADP-ribose) polymerase.

  17. Microinjection of l-glutamate into the nucleus ambiguus partially inhibits gastric motility through the NMDA receptor - nitric oxide pathway.

    PubMed

    Sun, Hong-Zhao; Zhao, Shu-Zhen; Ai, Hong-Bin

    2014-06-01

    We have previously reported that both l-glutamate (l-Glu) and nitric oxide (NO) modulate gastric motility in the nucleus ambiguus (NA). The aim of this study is to explore the potential correlation between the l-Glu and NO. A latex balloon connected to a pressure transducer was inserted into the pylorus through the fundus of anesthetized male Wistar rats to continuously record changes in gastric smooth muscle contractile curves. Pretreatment with the NO-synthase inhibitor N-nitro-l-arginine methylester (l-NAME) did not completely abolish the inhibitory effect of l-Glu on gastric motility, but intravenous injection of the ganglionic blocker hexamethonium bromide (Hb) did. By using a specific N-methyl-d-aspartic acid (NMDA) receptor antagonist, we blocked the inhibitory effect of the NO-donor sodium nitroprusside (SNP) on gastric motility. These results suggest that microinjections of l-Glu into the NA inhibits gastric motility by activating the cholinergic preganglionic neurons, partially through the NMDA receptor - NO pathway.

  18. High Concentrations of Tranexamic Acid Inhibit Ionotropic Glutamate Receptors.

    PubMed

    Lecker, Irene; Wang, Dian-Shi; Kaneshwaran, Kirusanthy; Mazer, C David; Orser, Beverley A

    2017-07-01

    The antifibrinolytic drug tranexamic acid is structurally similar to the amino acid glycine and may cause seizures and myoclonus by acting as a competitive antagonist of glycine receptors. Glycine is an obligatory co-agonist of the N-methyl-D-aspartate (NMDA) subtype of glutamate receptors. Thus, it is plausible that tranexamic acid inhibits NMDA receptors by acting as a competitive antagonist at the glycine binding site. The aim of this study was to determine whether tranexamic acid inhibits NMDA receptors, as well as α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid and kainate subtypes of ionotropic glutamate receptors. Tranexamic acid modulation of NMDA, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, and kainate receptors was studied using whole cell voltage-clamp recordings of current from cultured mouse hippocampal neurons. Tranexamic acid rapidly and reversibly inhibited NMDA receptors (half maximal inhibitory concentration = 241 ± 45 mM, mean ± SD; 95% CI, 200 to 281; n = 5) and shifted the glycine concentration-response curve for NMDA-evoked current to the right. Tranexamic acid also inhibited α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (half maximal inhibitory concentration = 231 ± 91 mM; 95% CI, 148 to 314; n = 5 to 6) and kainate receptors (half maximal inhibitory concentration = 90 ± 24 mM; 95% CI, 68 to 112; n = 5). Tranexamic acid inhibits NMDA receptors likely by reducing the binding of the co-agonist glycine and also inhibits α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid and kainate receptors. Receptor blockade occurs at high millimolar concentrations of tranexamic acid, similar to the concentrations that occur after topical application to peripheral tissues. Glutamate receptors in tissues including bone, heart, and nerves play various physiologic roles, and tranexamic acid inhibition of these receptors may contribute to adverse drug effects.

  19. Activation of N-methyl-d-aspartate receptors reduces heart rate variability and facilitates atrial fibrillation in rats.

    PubMed

    Shi, Shaobo; Liu, Tao; Wang, Dandan; Zhang, Yan; Liang, Jinjun; Yang, Bo; Hu, Dan

    2017-07-01

    The goal of this study was to assess the effects of N-methyl-d-aspartate (NMDA) receptors activation on heart rate variability (HRV) and susceptibility to atrial fibrillation (AF). Rats were randomized for treatment with saline, NMDA (agonist of NMDA receptors), or NMDA plus MK-801 (antagonist of NMDA receptors) for 2 weeks. Heart rate variability was evaluated by using implantable electrocardiogram telemeters. Atrial fibrillation susceptibility was assessed with programmed stimulation in isolated hearts. Compared with the controls, the NMDA-treated rats displayed a decrease in the standard deviation of normal RR intervals, the standard deviation of the average RR intervals, the mean of the 5-min standard deviations of RR intervals, the root mean square of successive differences, and high frequency (HF); and an increase in low frequency (LF) and LF/HF (all P< 0.01). Additionally, the NMDA-treated rats showed prolonged activation latency and reduced effective refractory period (all P< 0.01). Importantly, AF was induced in all NMDA-treated rats. While atrial fibrosis developed, connexin40 downgraded and metalloproteinase 9 upgraded in the NMDA-treated rats (all P< 0.01). Most of the above alterations were mitigated by co-administering with MK-801. These results indicate that NMDA receptors activation reduces HRV and enhances AF inducibility, with cardiac autonomic imbalance, atrial fibrosis, and degradation of gap junction protein identified as potential mechanistic contributors. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.

  20. Subunit Arrangement and Phenylethanolamine Binding in GluN1/GluN2B NMDA Receptors

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    E Karakas; N Simorowski; H Furukawa

    2011-12-31

    Since it was discovered that the anti-hypertensive agent ifenprodil has neuroprotective activity through its effects on NMDA (N-methyl-D-aspartate) receptors, a determined effort has been made to understand the mechanism of action and to develop improved therapeutic compounds on the basis of this knowledge. Neurotransmission mediated by NMDA receptors.

  1. Glutamate: Tastant and Neuromodulator in Taste Buds.

    PubMed

    Vandenbeuch, Aurelie; Kinnamon, Sue C

    2016-07-01

    In taste buds, glutamate plays a double role as a gustatory stimulus and neuromodulator. The detection of glutamate as a tastant involves several G protein-coupled receptors, including the heterodimer taste receptor type 1, member 1 and 3 as well as metabotropic glutamate receptors (mGluR1 and mGluR4). Both receptor types participate in the detection of glutamate as shown with knockout animals and selective antagonists. At the basal part of taste buds, ionotropic glutamate receptors [N-methyl-d-aspartate (NMDA) and non-NMDA] are expressed and participate in the modulation of the taste signal before its transmission to the brain. Evidence suggests that glutamate has an efferent function on taste cells and modulates the release of other neurotransmitters such as serotonin and ATP. This short article reviews the recent developments in the field with regard to glutamate receptors involved in both functions as well as the influence of glutamate on the taste signal. © 2016 American Society for Nutrition.

  2. A role for D-aspartate oxidase in schizophrenia and in schizophrenia-related symptoms induced by phencyclidine in mice

    PubMed Central

    Errico, F; D'Argenio, V; Sforazzini, F; Iasevoli, F; Squillace, M; Guerri, G; Napolitano, F; Angrisano, T; Di Maio, A; Keller, S; Vitucci, D; Galbusera, A; Chiariotti, L; Bertolino, A; de Bartolomeis, A; Salvatore, F; Gozzi, A; Usiello, A

    2015-01-01

    Increasing evidence points to a role for dysfunctional glutamate N-methyl-D-aspartate receptor (NMDAR) neurotransmission in schizophrenia. D-aspartate is an atypical amino acid that activates NMDARs through binding to the glutamate site on GluN2 subunits. D-aspartate is present in high amounts in the embryonic brain of mammals and rapidly decreases after birth, due to the activity of the enzyme D-aspartate oxidase (DDO). The agonistic activity exerted by D-aspartate on NMDARs and its neurodevelopmental occurrence make this D-amino acid a potential mediator for some of the NMDAR-related alterations observed in schizophrenia. Consistently, substantial reductions of D-aspartate and NMDA were recently observed in the postmortem prefrontal cortex of schizophrenic patients. Here we show that DDO mRNA expression is increased in prefrontal samples of schizophrenic patients, thus suggesting a plausible molecular event responsible for the D-aspartate imbalance previously described. To investigate whether altered D-aspartate levels can modulate schizophrenia-relevant circuits and behaviors, we also measured the psychotomimetic effects produced by the NMDAR antagonist, phencyclidine, in Ddo knockout mice (Ddo−/−), an animal model characterized by tonically increased D-aspartate levels since perinatal life. We show that Ddo−/− mice display a significant reduction in motor hyperactivity and prepulse inhibition deficit induced by phencyclidine, compared with controls. Furthermore, we reveal that increased levels of D-aspartate in Ddo−/− animals can significantly inhibit functional circuits activated by phencyclidine, and affect the development of cortico–hippocampal connectivity networks potentially involved in schizophrenia. Collectively, the present results suggest that altered D-aspartate levels can influence neurodevelopmental brain processes relevant to schizophrenia. PMID:25689573

  3. Blockade of N-methyl-d-aspartate receptor activation suppresses learning-induced synaptic elimination

    PubMed Central

    Bock, Jörg; Braun, Katharina

    1999-01-01

    Auditory filial imprinting in the domestic chicken is accompanied by a dramatic loss of spine synapses in two higher associative forebrain areas, the mediorostral neostriatum/hyperstriatum ventrale (MNH) and the dorsocaudal neostriatum (Ndc). The cellular mechanisms that underlie this learning-induced synaptic reorganization are unclear. We found that local pharmacological blockade of N-methyl-d-aspartate (NMDA) receptors in the MNH, a manipulation that has been shown previously to impair auditory imprinting, suppresses the learning-induced spine reduction in this region. Chicks treated with the NMDA receptor antagonist 2-amino-5-phosphonovaleric acid (APV) during the behavioral training for imprinting (postnatal day 0–2) displayed similar spine frequencies at postnatal day 7 as naive control animals, which, in both groups, were significantly higher than in imprinted animals. Because the average dendritic length did not differ between the experimental groups, the reduced spine frequency can be interpreted as a reduction of the total number of spine synapses per neuron. In the Ndc, which is reciprocally connected with the MNH and not directly influenced by the injected drug, learning-induced spine elimination was partly suppressed. Spine frequencies of the APV-treated, behaviorally trained but nonimprinted animals were higher than in the imprinted animals but lower than in the naive animals. These results provide evidence that NMDA receptor activation is required for the learning-induced selective reduction of spine synapses, which may serve as a mechanism of information storage specific for juvenile emotional learning events. PMID:10051669

  4. Investigating dynamic structural and mechanical changes of neuroblastoma cells associated with glutamate-mediated neurodegeneration

    NASA Astrophysics Data System (ADS)

    Fang, Yuqiang; Iu, Catherine Y. Y.; Lui, Cathy N. P.; Zou, Yukai; Fung, Carmen K. M.; Li, Hung Wing; Xi, Ning; Yung, Ken K. L.; Lai, King W. C.

    2014-11-01

    Glutamate-mediated neurodegeneration resulting from excessive activation of glutamate receptors is recognized as one of the major causes of various neurological disorders such as Alzheimer's and Huntington's diseases. However, the underlying mechanisms in the neurodegenerative process remain unidentified. Here, we investigate the real-time dynamic structural and mechanical changes associated with the neurodegeneration induced by the activation of N-methyl-D-aspartate (NMDA) receptors (a subtype of glutamate receptors) at the nanoscale. Atomic force microscopy (AFM) is employed to measure the three-dimensional (3-D) topography and mechanical properties of live SH-SY5Y cells under stimulus of NMDA receptors. A significant increase in surface roughness and stiffness of the cell is observed after NMDA treatment, which indicates the time-dependent neuronal cell behavior under NMDA-mediated neurodegeneration. The present AFM based study further advance our understanding of the neurodegenerative process to elucidate the pathways and mechanisms that govern NMDA induced neurodegeneration, so as to facilitate the development of novel therapeutic strategies for neurodegenerative diseases.

  5. Modafinil restores methamphetamine induced object-in-place memory deficits in rats independent of glutamate N-methyl d-aspartate receptor expression

    PubMed Central

    Reichel, Carmela M.; Gilstrap, Meghin G.; Ramsey, Lauren A.; See, Ronald E.

    2013-01-01

    Background Chronic methamphetamine (meth) abuse in humans can lead to various cognitive deficits, including memory loss. We previously showed that chronic meth self-administration impairs memory for objects relative to their location and surrounding objects. Here, we demonstrate that the cognitive enhancer, modafinil, reversed this cognitive impairment independent of glutamate N-methyl d-aspartate (GluN) receptor expression. Methods Male, Long-Evans rats underwent a noncontingent (Experiment 1) or contingent (Experiment 2) meth regimen. After one week of abstinence, rats were tested for object-in-place recognition memory. Half the rats received either vehicle or modafinil (100 mg/kg) immediately after object familiarization. Rats (Experiment 2) were sacrificed immediately after the test and brain areas that comprise the key circuitry for object in place performance were manually dissected. Subsequently, glutamate receptor expression was measured from a crude membrane fraction using western blot procedures. Results Saline-treated rats spent more time interacting with the objects in changed locations, while meth-treated rats distributed their time equally among all objects. Meth-treated rats that received modafinil showed a reversal in the deficit, whereby they spent more time exploring the objects in the new locations. GluN2B receptor subtype was decreased in the perirhinal cortex, yet remained unaffected in the prefrontal cortex and hippocampus of meth rats. This meth-induced down regulation occurred whether or not meth experienced rats received vehicle or modafinil. Conclusions These data support the use of modafinil for memory impairment in meth addiction. Further studies are needed to elucidate the neural mechanisms of modafinil reversal of cognitive impairments. PMID:24120858

  6. Nonparaneoplastic anti-N-methyl-D-aspartate receptor encephalitis: a case series of four children.

    PubMed

    Raha, Sarbani; Gadgil, Pradnya; Sankhla, Charulata; Udani, Vrajesh

    2012-04-01

    A rare, severe form of immune-mediated encephalitis recently has been described, associated with antibodies against N-methyl-D-aspartate receptors. It is reported mostly in women with ovarian tumors. Nonparaneoplastic presentations are less common. We describe four children with a neuropsychiatric and extrapyramidal syndrome associated with the presence of anti-N-methyl-D-aspartate receptor antibodies in cerebrospinal fluid and serum, without evidence of neoplasia. Three children recovered completely after immunomodulatory therapy, i.e., intravenous immunoglobulin and/or steroids, methylprednisolone, and/or adrenocorticotrophic hormone. Copyright © 2012 Elsevier Inc. All rights reserved.

  7. A novel photoaffinity ligand for the phencyclidine site of the N-methyl-D-aspartate receptor labels a Mr 120,000 polypeptide

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sonders, M.S.; Barmettler, P.; Lee, J.A.

    1990-04-25

    A radiolabeled photoaffinity ligand has been developed for the N-methyl-D-aspartate (NMDA)-preferring excitatory amino acid receptor complex. (3H)3-Azido-(5S, 10R)(+)-5-methyl-10,11-dihydro-5H- dibenzo(a,d)cyclohepten-5,10-imine (3H)3-azido-MK-801 demonstrated nearly identical affinity, density of binding sites, selectivity, pH sensitivity, and pharmacological profile in reversible binding assays with guinea pig brain homogenates to those displayed by its parent compound, MK-801. When employed in a photo-labeling protocol designed to optimize specific incorporation, (3H)3-azido-MK-801 labeled a single protein band which migrated in sodium dodecyl sulfate-polyacrylamide gels with Mr = 120,000. Incorporation of tritium into this band was completely inhibited when homogenates and (3H)3-azido-MK-801 were coincubated with 10 microM phencyclidine. These datamore » suggest that the phencyclidine site of the NMDA receptor complex is at least in part comprised of a Mr = 120,000 polypeptide.« less

  8. Functional ionotropic glutamate receptors on peripheral axons and myelin.

    PubMed

    Christensen, Pia Crone; Welch, Nicole Cheryl; Brideau, Craig; Stys, Peter K

    2016-09-01

    Neurotransmitter-dependent signaling is traditionally restricted to axon terminals. However, receptors are present on myelinating glia, suggesting that chemical transmission may also occur along axons. Confocal microscopy and Ca(2+) -imaging using an axonally expressed FRET-based reporter was used to measure Ca(2+) changes and morphological alterations in myelin in response to stimulation of glutamate receptors. Activation of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) or N-methyl-D-aspartate (NMDA) receptors induced a Ca(2+) increase in axon cylinders. However, only the latter caused structural alterations in axons, despite similar Ca(2+) increases. Myelin morphology was significantly altered by NMDA receptor activation, but not by AMPA receptors. Cu(2+) ions influenced the NMDA receptor-dependent response, suggesting that this metal modulates axonal receptors. Glutamate increased ribosomal signal in Schwann cell cytoplasm. Axon cylinders and myelin of peripheral nervous system axons respond to glutamate, with a consequence being an increase in Schwann cell ribosomes. This may have implications for nerve pathology and regeneration. Muscle Nerve 54: 451-459, 2016. © 2016 Wiley Periodicals, Inc.

  9. Comparison of the neuropsychological mechanisms of 2,6-diisopropylphenol and N-methyl-D-aspartate receptor antagonist against electroconvulsive therapy-induced learning and memory impairment in depressed rats.

    PubMed

    Liu, Gang; Liu, Chao; Zhang, Xue-Ning

    2015-09-01

    The present study aimed to examine the neurophysiological mechanisms of the 2,6-diisopropylphenol and N-methyl-D-aspartate (NMDA) receptor antagonist against learning and memory impairment, induced by electroconvulsive therapy (ECT). A total of 48 adult depressed rats without olfactory bulbs were randomly divided into six experimental groups: i) saline; ii) 10 mg/kg MK‑801; iii) 10 mg/kg MK‑801 and a course of ECT; iv) 200 mg/kg 2,6‑diisopropylphenol; v) 200 mg/kg 2,6‑diisopropylphenol and a course of ECT; and vi) saline and a course of ECT. The learning and memory abilities of the rats were assessed using a Morris water maze 1 day after a course of ECT. The hippocampus was removed 1 day after assessment using the Morris water maze assessment. The content of glutamate in the hippocampus was detected using high‑performance liquid chromatography. The expression levels of p‑AT8Ser202 and GSK‑3β1H8 in the hippocampus were determined using immunohistochemical staining and western blot analysis. The results demonstrated that the 2,6‑diisopropylphenol NMDA receptor antagonist, MK‑801 and ECT induced learning and memory impairment in the depressed rats. The glutamate content was significantly upregulated by ECT, reduced by 2,6‑diisopropylphenol, and was unaffected by the NMDA receptor antagonist in the hippocampus of the depressed rats. Tau protein hyperphosphorylation in the hippocampus was upregulated by ECT, but was reduced by 2,6‑diisopropylphenol and the MK‑801 NMDA receptor antagonist. It was also demonstrated that 2,6‑diisopropylphenol prevented learning and memory impairment and reduced the hyperphosphorylation of the Tau protein, which was induced by eECT. GSK‑3β was found to be the key protein involved in this signaling pathway. The ECT reduced the learning and memory impairment, caused by hyperphosphorylation of the Tau protein, in the depressed rats by upregulating the glutamate content.

  10. Anti-N-methyl-D-aspartate receptor encephalitis after Herpes simplex virus-associated encephalitis: an emerging disease with diagnosis and therapeutic challenges.

    PubMed

    Schein, Flora; Gagneux-Brunon, Amandine; Antoine, Jean-Christophe; Lavernhe, Sylvie; Pillet, Sylvie; Paul, Stéphane; Frésard, Anne; Boutet, Claire; Grange, Rémi; Cazorla, Céline; Lucht, Frédéric; Botelho-Nevers, Elisabeth

    2017-08-01

    Morbidity and mortality of Herpes simplex virus encephalitis (HSE) remain high. Relapses of neurological signs may occur after initial clinical improvement under acyclovir treatment. We report here a case of post-HSE anti-N-methyl-d-aspartate receptor-mediated encephalitis in an adult and perform a systematic search on PubMed to identify other cases in adults. We identified 11 previously published cases, to discuss diagnostic and therapeutic management. Symptoms in adults are often inappropriate behaviors, confusion and agitation. Diagnosis of anti-NMDA-R encephalitis after HSE is often delayed. Treatment consists in steroids, plasma exchange, and rituximab. Prognosis is often favorable. Anti-NMDA-R antibodies should be searched in cerebrospinal fluid of patients with unexpected evolution of HSE. This emerging entity reopens the hot debate about steroids in HSE.

  11. Rehabilitation for a child with recalcitrant anti-N-methyl-d-aspartate receptor encephalitis: case report and literature review

    PubMed Central

    Guo, Yao-Hong; Kuan, Ta-Shen; Hsieh, Pei-Chun; Lien, Wei-Chih; Chang, Chun-Kai; Lin, Yu-Ching

    2014-01-01

    Anti-N-methyl-d-aspartate (anti-NMDA) receptor encephalitis is a newly recognized, potentially fatal, but treatable autoimmune disease. Good outcome predictors include milder severity of symptoms, no need for intensive care unit admission, early aggressive immunotherapy, and prompt tumor removal. We report a case of a young girl aged 3 years 2 months and diagnosed as recalcitrant anti-NMDA receptor encephalitis without any underlying neoplasm. The patient had initial symptoms of behavioral changes that progressed to generalized choreoathetosis and orofacial dyskinesia, which resulted in 6 months of hospitalization in the pediatric intensive care unit. One year after initial onset of the disease, she had only achieved the developmental age of an infant aged 6–8 months in terms of gross and fine motor skills, but she resumed total independence in activities of daily living after receiving extensive immunotherapy and 28 months of rehabilitation. Our brief review will help clinical practitioners become more familiar with this disease and the unique rehabilitation programs. PMID:25473290

  12. AMPA, NMDA and kainate glutamate receptor subunits are expressed in human peripheral blood mononuclear cells (PBMCs) where the expression of GluK4 is altered by pregnancy and GluN2D by depression in pregnant women.

    PubMed

    Bhandage, Amol K; Jin, Zhe; Hellgren, Charlotte; Korol, Sergiy V; Nowak, Krzysztof; Williamsson, Louise; Sundström-Poromaa, Inger; Birnir, Bryndis

    2017-04-15

    The amino acid glutamate opens cation permeable ion channels, the iGlu receptors. These ion channels are abundantly expressed in the mammalian brain where glutamate is the main excitatory neurotransmitter. The neurotransmitters and their receptors are being increasingly detected in the cells of immune system. Here we examined the expression of the 18 known subunits of the iGlu receptors families; α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), kainate, N-methyl-d-aspartate (NMDA) and delta in human peripheral blood mononuclear cells (PBMCs). We compared the expression of the subunits between four groups: men, non-pregnant women, healthy pregnant women and depressed pregnant women. Out of 18 subunits of the iGlu receptors, mRNAs for 11 subunits were detected in PBMCs from men and non-pregnant women; AMPA: GluA3, GluA4, kainate: GluK2, GluK4, GluK5, NMDA: GluN1, GluN2C, GluN2D, GluN3A, GluN3B, and delta: GluD1. In the healthy and the depressed pregnant women, in addition, the delta GluD2 subunit was identified. The mRNAs for GluK4, GluK5, GluN2C and GluN2D were expressed at a higher level than other subunits. Gender, pregnancy or depression during pregnancy altered the expression of GluA3, GluK4, GluN2D, GluN3B and GluD1 iGlu subunit mRNAs. The greatest changes recorded were the lower GluA3 and GluK4 mRNA levels in pregnant women and the higher GluN2D mRNA level in healthy but not in depressed pregnant women as compared to non-pregnant individuals. Using subunit specific antibodies, the GluK4, GluK5, GluN1, GluN2C and GluN2D subunit proteins were identified in the PBMCs. The results show expression of specific iGlu receptor subunit in the PBMCs and support the idea of physiology-driven changes of iGlu receptors subtypes in the immune cells. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Schizophrenia, dissociative anaesthesia and near-death experience; three events meeting at the NMDA receptor.

    PubMed

    Bonta, Iván L

    2004-01-01

    The three events, viz. schizophrenia, dissociative anaesthesia and Near-Death Experience, despite their seemingly unrelated manifestation to each other, have nevertheless similar functional basis. All three events are linked to the glutamate sensitive N-methyl-D-aspartate (NMDA) receptor complex, which serves as their common functional denominator. Arguments and speculations are presented in favor of the view that, the three events might be considered as functional models of each other. Antagonism to the recognition NMDA-site of the receptor induces dissociative anaesthesia and precipitates Near-Death Experience. Agonist reinforcement at the modulatory glycine-site of the receptor counteracts negative symptoms of schizophrenia. Both types of challenges towards the receptor are compatible with a glutamate deficiency concept which underlies the meeting of the three events at the NMDA receptor.

  14. Effects of the NMDA receptor antagonist, D-CPPene, on sensitization to the operant decrement produced by naloxone in morphine-treated rats.

    PubMed

    Bespalov, A Y; Medvedev, I O; Sukhotina, I A; Zvartau, E E

    2001-04-01

    Sensitization to the rate-decreasing effects of opioid antagonists induced by acute pretreatment with opioid agonists has been suggested to reflect initial changes in opioid systems that underlie physical dependence. Glutamate receptors are implicated in the development and expression of opioid dependence, and antagonists acting at the N-methyl-D-aspartate (NMDA) subtype of glutamate receptors have been shown repeatedly to attenuate the severity of opioid withdrawal. The present study evaluated the ability of a competitive NMDA receptor antagonist, D-CPPene (SDZ EAA 494; 3-(2-carboxypiperazin-4-yl)-1-propenyl-1-phosphonic acid), to affect morphine-induced sensitization to naloxone in rats trained to lever-press on a multiple-trial, fixed-ratio 10 schedule of food reinforcement. D-CPPene (0.3-3 mg/kg) was administered either 4 h or 30 min prior to the test session. Morphine (10 mg/kg) or its vehicle was administered 4 h before naloxone challenge (0.3-3 mg/kg). D-CPPene failed to prevent morphine-induced potentiation of the naloxone-produced decrement in operant performance. Thus, these results suggest that agonist-induced sensitization to behavioral effects of opioid antagonists may be insensitive to NMDA receptor blockade.

  15. Acute D2/D3 dopaminergic agonism but chronic D2/D3 antagonism prevents NMDA antagonist neurotoxicity.

    PubMed

    Farber, Nuri B; Nemmers, Brian; Noguchi, Kevin K

    2006-09-15

    Antagonists of the N-methyl-D-aspartate (NMDA) glutamate receptor, most likely by producing disinhibtion in complex circuits, acutely produce psychosis and cognitive disturbances in humans, and neurotoxicity in rodents. Studies examining NMDA Receptor Hypofunction (NRHypo) neurotoxicity in animals, therefore, may provide insights into the pathophysiology of psychotic disorders. Dopaminergic D2 and/or D3 agents can modify psychosis over days to weeks, suggesting involvement of these transmitter system(s). We studied the ability of D2/D3 agonists and antagonists to modify NRHypo neurotoxicity both after a one-time acute exposure and after chronic daily exposure. Here we report that D2/D3 dopamine agonists, probably via D3 receptors, prevent NRHypo neurotoxicity when given acutely. The protective effect with D2/D3 agonists is not seen after chronic daily dosing. In contrast, the antipsychotic haloperidol does not affect NRHypo neurotoxicity when given acutely at D2/D3 doses. However, after chronic daily dosing of 1, 3, or 5 weeks, haloperidol does prevent NRHypo neurotoxicity with longer durations producing greater protection. Understanding the changes that occur in the NRHypo circuit after chronic exposure to dopaminergic agents could provide important clues into the pathophysiology of psychotic disorders.

  16. Large variability in synaptic N-methyl-D-aspartate receptor density on interneurons and a comparison with pyramidal-cell spines in the rat hippocampus.

    PubMed

    Nyíri, G; Stephenson, F A; Freund, T F; Somogyi, P

    2003-01-01

    Pyramidal cells receive input from several types of GABA-releasing interneurons and innervate them reciprocally. Glutamatergic activation of interneurons involves both alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and N-methyl-D-aspartate (NMDA) type glutamate receptors expressed in type I synapses, mostly on their dendritic shafts. On average, the synaptic AMPA receptor content is several times higher on interneurons than in the spines of pyramidal cells. To compare the NMDA receptor content of synapses, we used a quantitative postembedding immunogold technique on serial electron microscopic sections, and analysed the synapses on interneuron dendrites and pyramidal cell spines in the CA1 area. Because all NMDA receptors contain the obligatory NR1 subunit, receptor localisation was carried out using antibodies recognising all splice variants of the NR1 subunit. Four populations of synapse were examined: i). on spines of pyramidal cells in stratum (str.) radiatum and str. oriens; ii). on parvalbumin-positive interneuronal dendritic shafts in str. radiatum; iii). on randomly found dendritic shafts in str. oriens and iv). on somatostatin-positive interneuronal dendritic shafts and somata in str. oriens. On average, the size of the synapses on spines was about half of those on interneurons. The four populations of synapse significantly differed in labelling for the NR1 subunit. The median density of NR1 subunit labelling was highest on pyramidal cell spines. It was lowest in the synapses on parvalbumin-positive dendrites in str. radiatum, where more than half of these synapses were immunonegative. In str. oriens, synapses on interneurons had a high variability of receptor content; some dendrites were similar to those in str. radiatum, including the proximal synapses of somatostatin-positive cells, whereas others had immunoreactivity for the NR1 subunit similar to or higher than synapses on pyramidal cell spines. These results show that synaptic NMDA

  17. Hypothesis: is infantile autism a hypoglutamatergic disorder? Relevance of glutamate - serotonin interactions for pharmacotherapy.

    PubMed

    Carlsson, M L

    1998-01-01

    Based on 1) neuroanatomical and neuroimaging studies indicating aberrations in brain regions that are rich in glutamate neurons and 2) similarities between symptoms produced by N-methyl-D-aspartate (NMDA) antagonists in healthy subjects and those seen in autism, it is proposed in the present paper that infantile autism is a hypoglutamatergic disorder. Possible future pharmacological interventions in autism are discussed in the light of the intimate interplay between central glutamate and serotonin, notably the serotonin (5-HT) 2A receptor. The possible benefit of treatment with glutamate agonists [e.g. agents acting on the modulatory glycine site of the NMDA receptor, or so-called ampakines acting on the alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor] is discussed, as well as the potential usefulness of a selective 5-HT2A receptor antagonist.

  18. Small-molecule inhibitors at the PSD-95/nNOS interface protect against glutamate-induced neuronal atrophy in primary cortical neurons.

    PubMed

    Doucet, M V; O'Toole, E; Connor, T; Harkin, A

    2015-08-20

    Glutamate and nitric oxide (NO) are important regulators of dendrite and axon development in the central nervous system. Excess glutamatergic stimulation is a feature of many pathological conditions and manifests in neuronal atrophy and shrinkage with eventual neurodegeneration and cell death. Here we demonstrate that treatment of cultured primary cortical rat neurons for 24h with glutamate (500μM) or N-methyl-d-aspartate (NMDA) (100-500μM) combined with glycine suppresses neurite outgrowth. A similar reduction of neurite outgrowth was observed with the NO precursor l-arginine and NO donor sodium nitroprusside (SNP) (100 and 300μM). The NMDA-receptor (NMDA-R) antagonists ketamine and MK-801 (10nM) counteracted the NMDA/glycine-induced reduction in neurite outgrowth and the neuronal NO synthase (nNOS) inhibitor 1-[2-(trifluoromethyl)phenyl] imidazole (TRIM) (100nM) counteracted both the NMDA/glycine and l-arginine-induced decreases in neurite outgrowth. Furthermore, targeting soluble guanylate cyclase (sGC), a downstream target of NO, with the sGC inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) (10μM) also protected against l-arginine-induced decreases in neurite outgrowth. Since the NMDA-R is functionally coupled to nNOS via the postsynaptic protein 95kDa (PSD-95), inhibitors of the PSD-95/nNOS interaction were tested for their ability to protect against glutamate-induced suppression in neurite outgrowth. Treatment with the small-molecule inhibitors of the PSD-95/nNOS interface 2-((1H-benzo[d] [1,2,3]triazol-5-ylamino) methyl)-4,6-dichlorophenol (IC87201) (10 and 100nM) and 4-(3,5-dichloro-2-hydroxy-benzylamino)-2-hydroxybenzoic acid (ZL-006) (10 and 100nM) attenuated NMDA/glycine-induced decreases in neurite outgrowth. These data support the hypothesis that targeting the NMDA-R/PSD-95/nNOS interaction downstream of NMDA-R promotes neurotrophic effects by preventing neurite shrinkage in response to excess glutamatergic stimulation. The PSD-95/n

  19. D-Aspartate drinking solution alleviates pain and cognitive impairment in neuropathic mice.

    PubMed

    Palazzo, Enza; Luongo, Livio; Guida, Francesca; Marabese, Ida; Romano, Rosaria; Iannotta, Monica; Rossi, Francesca; D'Aniello, Antimo; Stella, Luigi; Marmo, Federica; Usiello, Alessandro; de Bartolomeis, Andrea; Maione, Sabatino; de Novellis, Vito

    2016-07-01

    D-Aspartate (D-Asp) is a free D-amino acid detected in multiple brain regions and putative precursor of endogenous N-methyl-D-aspartate (NMDA) acting as agonist at NMDA receptors. In this study, we investigated whether D-Asp (20 mM) in drinking solution for 1 month affects pain responses and pain-related emotional, and cognitive behaviour in a model of neuropathic pain induced by the spared nerve injury (SNI) of the sciatic nerve in mice. SNI mice developed mechanical allodynia and motor coordination impairment 30 days after SNI surgery. SNI mice showed cognitive impairment, anxiety and depression-like behaviour, reduced sociability in the three chamber sociability paradigm, increased expression of NR2B subunit of NMDA receptor and Homer 1a in the medial prefrontal cortex (mPFC). The expression of (post synaptic density) PSD-95 and Shank 1was instead unaffected in the mPFC of the SNI mice. Treatment with D-Asp drinking solution, started right after the SNI (day 0), alleviated mechanical allodynia, improved cognition and motor coordination and increased social interaction. D-Asp also restored the levels of extracellular D-Asp, Homer 1a and NR2B subunit of the NMDA receptor to physiological levels and reduced Shank1 and PSD-95 protein levels in the mPFC. Amitriptyline, a tricyclic antidepressant used also to alleviate neuropathic pain in humans, reverted mechanical allodynia and cognitive impairment, and unlike D-Asp, was effective in reducing depression and anxiety-like behaviour in the SNI mice and increased PSD protein level. Altogether these findings demonstrate that D-Asp improves sensorial, motor and cognitive-like symptoms related to chronic pain possibly through glutamate neurotransmission normalization in neuropathic mice.

  20. Ovarian Teratoma Associated with Coexisting Anti-N-Methyl-D-Aspartate Receptor and Glial Fibrillary Acidic Protein Autoimmune Meningoencephalitis in an Adolescent Girl: A Case Report.

    PubMed

    Martin, Alexandra L; Jolliffe, Evan; Hertweck, S Paige

    2018-06-01

    Ovarian teratomas are rarely associated with paraneoplastic autoimmune meningoencephalitis. In addition to the well known N-methyl-D-aspartate receptor (NMDA-R) antibody, the glial fibrillary acidic protein (GFAP) antibody is a novel biomarker of autoimmune meningoencephalitis that might be seen in patients with ovarian teratoma. A 13-year-old girl with acute-onset meningoencephalitis and incidental finding of ovarian teratoma was found to have coexisting anti-NMDA-R and GFAP antibodies present in her cerebrospinal fluid. NMDA-R and GFAP autoimmune encephalitis should be considered in adolescent patients with neurologic or psychiatric symptoms and an ovarian teratoma. Prompt diagnosis and surgical resection increase the likelihood of full neurologic recovery. Copyright © 2017 North American Society for Pediatric and Adolescent Gynecology. Published by Elsevier Inc. All rights reserved.

  1. Fluoxetine reverses the behavioral despair induced by neurogenic stress in mice: role of N-methyl-d-aspartate and opioid receptors.

    PubMed

    Haj-Mirzaian, Arya; Kordjazy, Nastaran; Ostadhadi, Sattar; Amiri, Shayan; Haj-Mirzaian, Arvin; Dehpour, AhmadReza

    2016-06-01

    Opioid and N-methyl-d-aspartate (NMDA) receptors mediate different effects of fluoxetine. We investigated whether opioid and NMDA receptors are involved in the protective effect of fluoxetine against the behavioral despair induced by acute physical stress in male mice. We used the forced swimming test (FST), tail suspension test (TST), and open-field test (OFT) for behavioral evaluation. We used fluoxetine, naltrexone (opioid receptor antagonist), MK-801 (NMDA receptor antagonist), morphine (opioid receptor agonist), and NMDA (NMDA receptor agonist). Acute foot-shock stress (FSS) significantly induced behavioral despair (depressive-like) and anxiety-like behaviors in tests. Fluoxetine (5 mg/kg) reversed the depressant-like effect of FSS, but it did not alter the locomotion and anxiety-like behavior in animals. Acute administration of subeffective doses of naltrexone (0.3 mg/kg) or MK-801 (0.01 mg/kg) potentiated the antidepressant-like effect of fluoxetine, while subeffective doses of morphine (1 mg/kg) and NMDA (75 mg/kg) abolished this effect of fluoxetine. Also, co-administration of subeffective doses of naltrexone (0.05 mg/kg) and MK-801 (0.003 mg/kg) with fluoxetine (1 mg/kg) induced a significant decrease in the immobility time in FST and TST. Our results showed that opioid and NMDA receptors (alone or in combination) are involved in the antidepressant-like effect of fluoxetine against physical stress.

  2. An N-methyl-D-aspartate receptor-independent excitatory action of partial reduction of extracellular [Mg2+] in CA1-region of rat hippocampal slices.

    PubMed

    Hamon, B; Stanton, P K; Heinemann, U

    1987-03-31

    Partial reduction of [Mg2+]o from 2 to 1 mM markedly enhanced neuronal responses evoked by Schaffer collateral-commissural fiber stimulation in the CA1-region of rat hippocampal slices. The amplitude of extracellular population potentials recorded in the CA1-pyramidal cell layer and maximum dV/dt of extracellular population EPSP's recorded in the CA1-pyramidal apical dendritic layer were both increased. However, unlike findings from slices where Mg2+ was completely removed from the bathing medium, there was no spontaneous or evoked epileptiform activity, and the N-methyl-D-aspartate (NMDA) receptor antagonist 2-amino-5-phosphonovalerate (2-APV) did not antagonize the enhancement of evoked responses. These results indicate that, in addition to the participation of NMDA receptors in the epileptiform activity observed when Mg2+ is completely removed from the bathing medium, there is also an NMDA receptor-independent excitatory action of partial reduction of [Mg2+]o in hippocampal slices.

  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. N-linked glycosylation of cortical N-methyl-D-aspartate and kainate receptor subunits in schizophrenia.

    PubMed

    Tucholski, Janusz; Simmons, Micah S; Pinner, Anita L; McMillan, Laurence D; Haroutunian, Vahram; Meador-Woodruff, James H

    2013-08-21

    Dysfunctional glutamate neurotransmission has been implicated in the pathophysiology of schizophrenia. Abnormal expressions in schizophrenia of ionotropic glutamate receptors (iGluRs) and the proteins that regulate their trafficking have been found to be region and subunit specific in brain, suggesting that abnormal trafficking of iGluRs may contribute toward altered glutamatergic neurotransmission. The post-translational modification N-glycosylation of iGluR subunits can be used as a proxy for their intracellular localization. Receptor complexes assemble in the lumen of the endoplasmic reticulum, where N-glycosylation begins with the addition of N-linked oligomannose glycans, and is subsequently trimmed and replaced by more elaborate glycans while trafficking through the Golgi apparatus. Previously, we found abnormalities in N-glycosylation of the GluR2 AMPA receptor subunit in schizophrenia. Here, we investigated N-glycosylation of N-methyl-D-aspartate and kainate (KA) receptor subunits in the dorsolateral prefrontal cortex from patients with schizophrenia and a comparison group. We used enzymatic deglycosylation with two glycosidases: endoglycosidase H (Endo H), which removes immature high mannose-containing sugars, and peptide-N-glycosidase F (PNGase F), which removes all N-linked sugars. The NR1, NR2A, NR2B, GluR6, and KA2 subunits were all sensitive to treatment with Endo H and PNGase F. The GluR6 KA receptor subunit was significantly more sensitive to Endo H-mediated deglycosylation in schizophrenia, suggesting a larger molecular mass of N-linked high mannose and/or hybrid sugars on GluR6. This finding, taken with our previous work, suggests that a cellular mechanism underlying abnormal glutamate neurotransmission in schizophrenia may involve abnormal trafficking of both AMPA and KA receptors.

  5. Excitotoxicity Induced by Realgar in the Rat Hippocampus: the Involvement of Learning Memory Injury, Dysfunction of Glutamate Metabolism and NMDA Receptors.

    PubMed

    Huo, Tao-guang; Li, Wei-kai; Zhang, Ying-hua; Yuan, Jie; Gao, Lan-yue; Yuan, Yuan; Yang, Hui-lei; Jiang, Hong; Sun, Gui-fan

    2015-01-01

    Realgar is a type of mineral drug containing arsenic. The nervous system toxicity of realgar has received extensive attention. However, the underlying mechanisms of realgar-induced neurotoxicity have not been clearly elucidated. To explore the mechanisms that contribute to realgar-induced neurotoxicity, weanling rats were exposed to realgar (0, 0.3, 0.9, 2.7 g/kg) for 6 weeks, and cognitive ability was tested using the Morris water maze (MWM) test and object recognition task (ORT). The levels of arsenic in the blood and hippocampus were monitored. The ultrastructures of hippocampal neurons were observed. The levels of glutamate (Glu) and glutamine (Gln) in the hippocampus and hippocampal CA1 region; the activities of glutamine synthetase (GS) and phosphate-activated glutaminase (PAG); the mRNA and protein expression of glutamate transporter 1 (GLT-1), glutamate/aspartate transporter (GLAST), and N-methyl-D-aspartate (NMDA) receptors; and the level of intracellular Ca(2+) were also investigated. The results indicate that the rats developed deficiencies in cognitive ability after a 6-week exposure to realgar. The arsenic contained in realgar and the arsenic metabolites passed through the blood-brain barrier (BBB) and accumulated in the hippocampus, which resulted in the excessive accumulation of Glu in the extracellular space. The excessive accumulation of Glu in the extracellular space induced excitotoxicity, which was shown by enhanced GS and PAG activities, inhibition of GLT-1 mRNA and protein expression, alterations in NMDA receptor mRNA and protein expression, disturbance of intracellular Ca(2+) homeostasis, and ultrastructural changes in hippocampal neurons. In conclusion, the findings from our study indicate that exposure to realgar induces excitotoxicity and that the mechanism by which this occurs may be associated with disturbances in Glu metabolism and transportation and alterations in NMDA receptor expression.

  6. 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

    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

  7. Increased cerebral oxygen consumption in Eker rats and effects of N-methyl-D-aspartate blockade: Implications for autism.

    PubMed

    Weiss, Harvey R; Liu, Xia; Zhang, Qihang; Chi, Oak Z

    2007-08-15

    Because there is a strong correlation between tuberous sclerosis and autism, we used a tuberous sclerosis model (Eker rat) to test the hypothesis that these animals would have an altered regional cerebral O2 consumption that might be associated with autism. We also examined whether the altered cerebral O2 consumption was related to changes in the importance of N-methyl-D-aspartate (NMDA) receptors. Young (4 weeks) male control Long Evans (N = 14) and Eker (N = 14) rats (70-100 g) were divided into control and CGS-19755 (10 mg/kg, competitive NMDA antagonist)-treated animals. Cerebral regional blood flow (14C-iodoantipyrine) and O2 consumption (cryomicrospectrophotometry) were determined in isoflurane-anesthetized rats. NMDA receptor protein levels were determined by Western immunoblotting. We found significantly increased basal O2 consumption in the cortex (6.2 +/- 0.6 ml O2/min/100 g Eker vs. 4.7 +/- 0.4 Long Evans), hippocampus, cerebellum, and pons. Regional cerebral blood flow was also elevated in Eker rats at baseline, but cerebral O2 extraction was similar. CGS-19755 significantly lowered O2 consumption in the cortex (2.8 +/- 0.3), hippocampus, and pons of the Long Evans rats but had no effect on cortex (5.8 +/- 0.8) or other regions of the Eker rats. Cerebral blood flow followed a similar pattern. NMDA receptor protein levels (NR1 subunit) were similar between groups. In conclusion, Eker rats had significantly elevated cerebral O2 consumption and blood flow, but this was not related to NMDA receptor activation. In fact, the importance of NMDA receptors in the control of basal cerebral O2 consumption was reduced. This might have important implications in the treatment of autism. Copyright 2007 Wiley-Liss, Inc.

  8. Direct binding of Toll-like receptor 4 to ionotropic glutamate receptor N-methyl-D-aspartate subunit 1 induced by lipopolysaccharide in microglial cells N9 and EOC 20.

    PubMed

    Cui, Jie; Yu, Siyuan; Li, Yihui; Li, Pan; Liu, Feng

    2018-03-01

    Microglia, the primary immune cells in the brain, are the predominant cells regulating inflammation-mediated neuronal damage. In response to immunological challenges, such as lipopolysaccharide (LPS), microglia are activated and the inflammatory process is subsequently initiated. The aim of the present study was to determine whether LPS induces interactions between the Toll-like receptor 4 (TLR4) and the ionotropic glutamate receptor N-methyl-D‑aspartate subunit 1 (GluN1) in N9 and EOC 20 microglial cells. Immunocytochemistry demonstrated co-localization of TLR4 and GluN1 in response to LPS, and the direct binding of TLR4 and GluN1 was further validated by antibody-based Fluorescence Resonance Energy Transfer technology. Inhibition of the group I metabotropic glutamate receptor 5 with its selective antagonist, MTEP, abolished LPS-induced direct binding of TLR4 to GluN1. Therefore, these data demonstrated that GluN1 and TLR4 act reciprocally in response to LPS in N9 and EOC 20 microglial cells.

  9. Glutamate receptor activation in the kindled dentate gyrus.

    PubMed

    Behr, J; Heinemann, U; Mody, I

    2000-01-01

    The contribution of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), N-methyl-D-aspartate (NMDA), and kainate receptor activation to the enhanced seizure susceptibility of the dentate gyrus was investigated in an experimental model of temporal lobe epilepsy. Using the specific NMDA and AMPA receptor antagonists D-APV and SYM 2206, we examined alterations in glutamate receptor-dependent synaptic currents 48 hours and 28 days after kindling in field-potential and voltage-clamp recordings. Forty-eight hours after kindling, the fractions of AMPA and NMDA receptor-mediated excitatory postsynaptic current components shifted dramatically in favor of the NMDA receptor-mediated response. Four weeks after kindling, however, AMPA and NMDA receptor-mediated excitatory postsynaptic currents reverted to control-like values. Neither single nor repetitive perforant path stimuli evoked kainate receptor-mediated excitatory postsynaptic currents in dentate gyrus granule cells of control or kindled rats. The enhanced excitability of the kindled dentate gyrus 48 hours after the last seizure most likely results from transiently enhanced NMDA receptor activation. The NMDA receptor seems to play a critical role in the induction of the kindled state rather than in the persistence of the enhanced seizure susceptibility.

  10. N-Methyl-D aspartate receptor-mediated effect on glucose transporter-3 levels of high glucose exposed-SH-SY5Y dopaminergic neurons.

    PubMed

    Engin, Ayse Basak; Engin, Evren Doruk; Karakus, Resul; Aral, Arzu; Gulbahar, Ozlem; Engin, Atilla

    2017-11-01

    High glucose and insulin lead to neuronal insulin resistance. Glucose transport into the neurons is achieved by regulatory induction of surface glucose transporter-3 (GLUT3) instead of the insulin. N-methyl-D aspartate (NMDA) receptor activity increases GLUT3 expression. This study explored whether an endogenous NMDA receptor antagonist, kynurenic acid (KynA) affects the neuronal cell viability at high glucose concentrations. SH-SY5Y neuroblastoma cells were exposed to 150-250 mg/dL glucose and 40 μU/mL insulin. In KynA and N-nitro-l-arginine methyl ester (L-NAME) supplemented cultures, oxidative stress, mitochondrial metabolic activity (MTT), nitric oxide as nitrite+nitrate (NOx) and GLUT3 were determined at the end of 24 and 48-h incubation periods. Viable cells were counted by trypan blue dye. High glucose-exposed SH-SY5Y cells showed two-times more GLUT3 expression at second 24-h period. While GLUT3-stimulated glucose transport and oxidative stress was increased, total mitochondrial metabolic activity was significantly reduced. Insulin supplementation to high glucose decreased NOx synthesis and GLUT3 levels, in contrast oxidative stress increased three-fold. KynA significantly reduced oxidative stress, and increased MTT by regulating NOx production and GLUT3 expression. KynA is a noteworthy compound, as an endogenous, specific NMDA receptor antagonist; it significantly reduces oxidative stress, while increasing cell viability at high glucose and insulin concentrations. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Competitive and noncompetitive antagonists at N-methyl-D-aspartate receptors protect against methamphetamine-induced dopaminergic damage in mice.

    PubMed

    Sonsalla, P K; Riordan, D E; Heikkila, R E

    1991-02-01

    The administration of methamphetamine (METH) to experimental animals results in damage to nigrostriatal dopaminergic neurons. We have demonstrated previously that the excitatory amino acids may be involved in this neurotoxicity. For example, several compounds which bind to the phenyclidine site within the ion channel linked to the N-methyl-D-aspartate (NMDA) receptor protected mice from the METH-induced loss of neostriatal tyrosine hydroxylase activity and dopamine content. The present study was conducted to characterize further the role of the excitatory amino acids in mediating the neurotoxic effects of METH. The administration of three or four injections of METH (10 mg/kg) every 2 hr to mice produced large decrements in neostriatal dopamine content (80-84%) and in tyrosine hydroxylase activity (65-74%). A dose-dependent protection against these METH-induced decreases was seen with two noncompetitive NMDA antagonists, ifenprodil and SL 82.0715 (25-50 mg/kg/injection), both of which are thought to bind to a polyamine or sigma site associated with the NMDA receptor complex, and with two competitive NMDA antagonists, CGS 19755 (25-50 mg/kg/injection) and NPC 12626 (150-300 mg/kg/injection). Moreover, an intrastriatal infusion of NMDA (0.1 mumol) produced a slight but significant loss of neostriatal dopamine which was potentiated in mice that also received a systemic injection of METH. The results of these studies strengthen the hypothesis that the excitatory amino acids play a critical role in the nigrostriatal dopaminergic damage induced by METH.

  12. d-Aspartate oxidase influences glutamatergic system homeostasis in mammalian brain.

    PubMed

    Cristino, Luigia; Luongo, Livio; Squillace, Marta; Paolone, Giovanna; Mango, Dalila; Piccinin, Sonia; Zianni, Elisa; Imperatore, Roberta; Iannotta, Monica; Longo, Francesco; Errico, Francesco; Vescovi, Angelo Luigi; Morari, Michele; Maione, Sabatino; Gardoni, Fabrizio; Nisticò, Robert; Usiello, Alessandro

    2015-05-01

    We have investigated the relevance of d-aspartate oxidase, the only enzyme known to selectively degrade d-aspartate (d-Asp), in modulating glutamatergic system homeostasis. Interestingly, the lack of the Ddo gene, by raising d-Asp content, induces a substantial increase in extracellular glutamate (Glu) levels in Ddo-mutant brains. Consistent with an exaggerated and persistent N-methyl-d-aspartate receptor (NMDAR) stimulation, we documented in Ddo knockouts severe age-dependent structural and functional alterations mirrored by expression of active caspases 3 and 7 along with appearance of dystrophic microglia and reactive astrocytes. In addition, prolonged elevation of d-Asp triggered in mutants alterations of NMDAR-dependent synaptic plasticity associated to reduction of hippocampal GluN1 and GluN2B subunits selectively located at synaptic sites and to increase in the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid-to-N-methyl-d-aspartate ratio. These effects, all of which converged on a progressive hyporesponsiveness at NMDAR sites, functionally resulted in a greater vulnerability to phencyclidine-induced prepulse inhibition deficits in mutants. In conclusion, our results indicate that d-aspartate oxidase, by strictly regulating d-Asp levels, impacts on the homeostasis of glutamatergic system, thus preventing accelerated neurodegenerative processes. Copyright © 2015 Elsevier Inc. All rights reserved.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    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-freemore » 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.« less

  14. Blockage of N-methyl-D-aspartate receptors decreases testosterone levels and enhances postnatal neuronal apoptosis in the preoptic area of male rats.

    PubMed

    Hsu, C; Hsieh, Y L; Yang, R C; Hsu, H K

    2000-05-01

    Sexual dimorphism has been found in the preoptic area of the hypothalamus (POA), a major site of glutamate actions via N-methyl-D-aspartate (NMDA) receptors. The sexually dimorphic nucleus of the preoptic area (SDN-POA) of male rats exhibits about seven-fold greater nuclear volume than that of females. A naturally occurring neonatal neuronal apoptosis, that can be prevented by testosterone, may contribute to this sexual difference in SDN-POA nuclear volume. Since activation of NMDA receptors in the POA induces GnRH secretion, it may be involved in both elevation of serum testosterone and prevention of neuronal death in the SDN-POA. In the present study, protein expression of NMDA receptors in the POA of male and female fetuses was quantified on the day preceding the fetal testosterone peak (embryonic day 16; ED 16). Rats were then distributed in four groups: (1) untreated males, (2) untreated females, (3) males pretreated with MK-801 (a noncompetitive NMDA receptor antagonist), and (4) females pretreated with MK-801. Serum levels of testosterone were estimated on the afternoon of ED 18. Expression of Bcl-2 and Bax, as well as neuronal apoptosis in SDN-POA, were observed on postnatal day 8. The results showed that (1) expression of NMDA receptors in the POA of male fetuses was higher than that of females on ED 16; (2) levels of testosterone were lower in MK-801 pretreated male fetuses than in intact males on ED 18; (3) expression of Bcl-2 in the POA of MK-801 pretreated male rats was significantly less than that of control males; (4) the apoptotic incidence in the SDN-POA of MK-801 pretreated male rats was significantly greater than in control males, while there was no significant difference in apoptotic incidence in the SDN-POA between MK-801 pretreated and intact females. These results suggest that the NMDA receptor is highly expressed in prenatal male fetuses, and that it might play an important role in the elevation of testosterone levels. Moreover, activation

  15. Interaction of ( sup 3 H)MK-801 with multiple states of the N-methyl-D-aspartate receptor complex of rat brain

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Javitt, D.C.; Zukin, S.R.

    1989-01-01

    N-Methyl-D-aspartate (N-Me-D-Asp) and phencyclidine receptors interactively mediate central nervous system processes including psychotomimetic effects of drugs as well as neurodegenerative, cognitive, and developmental events. To elucidate the mechanism of this interaction, effects of N-Me-D-Asp agonists and antagonists and of glycine-like agents upon binding of the radiolabeled phencyclidine receptor ligand ({sup 3}H)MK-801 were determined in rat brain. Scatchard analysis revealed two discrete components of ({sup 3}H)MK-801 binding after 4 hr of incubation. Incubation in the presence of L-glutamate led to an increase in apparent densities but not in affinities of both components of ({sup 3}H)MK-801 binding as well as conversion ofmore » sites from apparent low to high affinity. Incubation in the presence of combined D-serine and L-glutamate led to an increase in the apparent density of high-affinity ({sup 3}H)MK-801 binding compared with incubation in the presence of either L-glutamate or D-serine alone. These data support a model in which phencyclidine receptor ligands bind differentially to closed as well as open conformations of the N-Me-D-Asp receptor complex and in which glycine-like agents permit or facilitate agonist-induced conversion of N-Me-D-Asp receptors from closed to open conformations.« less

  16. Integration of contextual cues into memory depends on "prefrontal" N-methyl-D-aspartate receptors.

    PubMed

    Starosta, Sarah; Bartetzko, Isabelle; Stüttgen, Maik C; Güntürkün, Onur

    2017-10-01

    Every learning event is embedded in a context, but not always does the context become an integral part of the memory; however, for extinction learning it usually does, resulting in context-specific conditioned responding. The neuronal mechanisms underlying contextual control have been mainly investigated for Pavlovian fear extinction with a focus on hippocampal structures. However, the initial acquisition of novel responses can be subject to contextual control as well, although the neuronal mechanisms are mostly unknown. Here, we tested the hypothesis that contextual control of acquisition depends on glutamatergic transmission underlying executive functions in forebrain areas, e.g. by shifting attention to critical cues. Thus, we antagonized N-methyl-D-aspartate (NMDA) receptors with 2-amino-5-phosphonovaleric acid (AP5) in the pigeon nidopallium caudolaterale, the functional analogue of mammalian prefrontal cortex, during the concomitant acquisition and extinction of conditioned responding to two different stimuli. This paradigm has previously been shown to lead to contextual control over extinguished as well as non-extinguished responding. NMDA receptor blockade resulted in an impairment of extinction learning, but left the acquisition of responses to a novel stimulus unaffected. Critically, when responses were tested in a different context in the retrieval phase, we observed that NMDA receptor blockade led to the abolishment of contextual control over acquisition performance. This result is predicted by a model describing response inclination as the product of associative strength and contextual gain. In this model, learning under AP5 leads to a change in the contextual gain on the learned association, possibly via the modulation of attentional mechanisms. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Effects of ketamine and N-methyl-D-aspartate on fluoxetine-induced antidepressant-related behavior using the forced swimming test.

    PubMed

    Owolabi, Rotimi Adegbenga; Akanmu, Moses Atanda; Adeyemi, Oluwole Isaac

    2014-04-30

    This study investigated the effects of ketamine on fluoxetine-induced antidepressant behavior using the forced swimming test (FST) in mice. In order to understand the possible role of N-methyl-d-aspartate (NMDA) neurotransmission in the antidepressant effect of fluoxetine, different groups of mice (n=10) were administered with acute ketamine (3mg/kg, i.p.), acute NMDA (75mg/kg and 150mg/kg, i.p.) and a 21-day chronic ketamine (15mg/kg, i.p./day) were administered prior to the administration of fluoxetine (20mg/kg, i.p.) in the mice. Antidepressant related behavior (immobility score) was measured using the forced swimming test. The results showed that the acute ketamine and fluoxetine alone treatments elicited a significant (p<0.05) reduction in immobility score compared with saline control. Furthermore, pre-treatment with acute ketamine significantly enhanced by the fluoxetine-induced decrease in immobility score. In contrast, pre-treatment with NMDA (150mg/kg) significantly (p<0.05) reversed fluoxetine-induced decrease in immobility score. On the other hand, chronic administration of ketamine significantly elicited an increase in immobility score as well as reversed the reduction induced by fluoxetine. Similarly, NMDA administration at both 75mg/kg and 150mg/kg increased immobility score in chronically administered ketamine groups. Furthermore, chronic administration of ketamine, followed by NMDA (75mg/kg) and fluoxetine significantly elevated the immobility score when compared with the group that received NMDA and fluoxetine but not chronically treated with ketamine. It can be suggested) that facilitation of NMDA transmission blocked fluoxetine-induced reduction in immobility score, while down-regulation of NMDA transmission is associated with increase in fluoxetine-induced antidepressant-related behavior in mice. Down-regulation of the NMDA transmission is proposed as an essential component of mechanism of suppression of depression related behaviors by

  18. Learning and memory: regional changes in N-methyl-D-aspartate receptors in the chick brain after imprinting.

    PubMed Central

    McCabe, B J; Horn, G

    1988-01-01

    An extensive series of experiments has implicated a restricted region of the chick forebrain in the learning process of imprinting. The region is the intermediate and medial part of the hyperstriatum ventrale (IMHV). Previous studies have shown that training is associated with an increase in the area of the postsynaptic density of axospinous synapses in the left but not the right IMHV. The postsynaptic density is a site of high receptor density, and at least some axospinous synapses are excitatory. We found that imprinting is associated with a 59% increase in N-methyl-D-aspartate-sensitive binding of the excitatory amino acid L-[3H]glutamic acid in the left IMHV. The increase is probably due to an increased number of binding sites. The profile of sensitivity of the sites to a series of amino-, phosphono-substituted carboxylic acids (2-amino-3-phosphonopropionate to 2-amino-8-phosphonooctanoate) is characteristic of N-methyl-D-aspartate-type receptors. There were no significant effects of training on binding in the right IMHV. The effect of training on left IMHV binding could not be attributed to light exposure, arousal, or motor activity per se but was a function of how much the chicks learned. The changes in the left IMHV could increase the effectiveness of synaptic transmission in a region crucial for information storage and so form a neural basis for recognition memory. PMID:2833757

  19. Glutamate receptors modulate sodium-dependent and calcium-independent vitamin C bidirectional transport in cultured avian retinal cells.

    PubMed

    Portugal, Camila Cabral; Miya, Vivian Sayuri; Calaza, Karin da Costa; Santos, Rochelle Alberto Martins; Paes-de-Carvalho, Roberto

    2009-01-01

    Vitamin C is transported in the brain by sodium vitamin C co-transporter 2 (SVCT-2) for ascorbate and glucose transporters for dehydroascorbate. Here we have studied the expression of SVCT-2 and the uptake and release of [(14)C] ascorbate in chick retinal cells. SVCT-2 immunoreactivity was detected in rat and chick retina, specially in amacrine cells and in cells in the ganglion cell layer. Accordingly, SVCT-2 was expressed in cultured retinal neurons, but not in glial cells. [(14)C] ascorbate uptake was saturable and inhibited by sulfinpyrazone or sodium-free medium, but not by treatments that inhibit dehydroascorbate transport. Glutamate-stimulated vitamin C release was not inhibited by the glutamate transport inhibitor l-beta-threo-benzylaspartate, indicating that vitamin C release was not mediated by glutamate uptake. Also, ascorbate had no effect on [(3)H] D-aspartate release, ruling out a glutamate/ascorbate exchange mechanism. 2-Carboxy-3-carboxymethyl-4-isopropenylpyrrolidine (Kainate) or NMDA stimulated the release, effects blocked by their respective antagonists 6,7-initroquinoxaline-2,3-dione (DNQX) or (5R,2S)-(1)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine hydrogen maleate (MK-801). However, DNQX, but not MK-801 or 2-amino-5-phosphonopentanoic acid (APV), blocked the stimulation by glutamate. Interestingly, DNQX prevented the stimulation by NMDA, suggesting that the effect of NMDA was mediated by glutamate release and stimulation of non-NMDA receptors. The effect of glutamate was neither dependent on external calcium nor inhibited by 1,2-bis (2-aminophenoxy) ethane-N',N',N',N',-tetraacetic acid tetrakis (acetoxy-methyl ester) (BAPTA-AM), an internal calcium chelator, but was inhibited by sulfinpyrazone or by the absence of sodium. In conclusion, retinal cells take up and release vitamin C, probably through SVCT-2, and the release can be stimulated by NMDA or non-NMDA glutamate receptors.

  20. Roles of N-methyl-d-aspartate receptors during the sensory stimulation-evoked field potential responses in mouse cerebellar cortical molecular layer.

    PubMed

    Xu, Yin-Hua; Zhang, Guang-Jian; Zhao, Jing-Tong; Chu, Chun-Ping; Li, Yu-Zi; Qiu, De-Lai

    2017-11-01

    The functions of N-methyl-d-aspartate receptors (NMDARs) in cerebellar cortex have been widely studied under in vitro condition, but their roles during the sensory stimulation-evoked responses in the cerebellar cortical molecular layer in living animals are currently unclear. We here investigated the roles of NMDARs during the air-puff stimulation on ipsilateral whisker pad-evoked field potential responses in cerebellar cortical molecular layer in urethane-anesthetized mice by electrophysiological recording and pharmacological methods. Our results showed that cerebellar surface administration of NMDA induced a dose-dependent decrease in amplitude of the facial stimulation-evoked inhibitory responses (P1) in the molecular layer, accompanied with decreases in decay time, half-width and area under curve (AUC) of P1. The IC 50 of NMDA induced inhibition in amplitude of P1 was 46.5μM. In addition, application of NMDA induced significant increases in the decay time, half-width and AUC values of the facial stimulation-evoked excitatory responses (N1) in the molecular layer. Application of an NMDAR blocker, D-APV (250μM) abolished the facial stimulation-evoked P1 in the molecular layer. These results suggested that NMDARs play a critical role during the sensory information processing in cerebellar cortical molecular layer in vivo in mice. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Synthesis and Structure Activity Relationship of Tetrahydroisoquinoline-based Potentiators of GluN2C and GluN2D Containing N-Methyl-D-Aspartate Receptors

    PubMed Central

    Santangelo Freel, Rose M.; Ogden, Kevin K.; Strong, Katie L.; Khatri, Alpa; Chepiga, Kathryn M.; Jensen, Henrik S.; Traynelis, Stephen F.; Liotta, Dennis C.

    2015-01-01

    We describe here the synthesis and evaluation of a series of tetrahydroisoquinolines that show subunit-selective potentiation of NMDA receptors containing the GluN2C or GluN2D subunits. Bischler-Napieralski conditions were employed in the key step for the conversion of acyclic amides to the corresponding tetrahydroisoquinoline containing analogs. Compounds were evaluated using both two electrode voltage clamp recordings from Xenopus laevis oocytes and imaging of mammalian BHK cells loaded with Ca2+-sensitive dyes. The most potent analogues had EC50 values of 300 nM and showed over 2-fold potentiation of the response to maximally effective concentrations of glutamate and glycine, but had no effect on responses from NMDA receptors containing the GluN2A or GluN2B subunits, AMPA, kainate, GABA, or glycine receptors or a variety of other potential targets. These compounds represent a potent class of small molecule subunit-selective potentiators of NMDA receptors. PMID:23627311

  2. 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

  3. 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.

  4. Non-fibrillar amyloid-{beta} peptide reduces NMDA-induced neurotoxicity, but not AMPA-induced neurotoxicity

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Niidome, Tetsuhiro, E-mail: tniidome@pharm.kyoto-u.ac.jp; Goto, Yasuaki; Kato, Masaru

    2009-09-04

    Amyloid-{beta} peptide (A{beta}) is thought to be linked to the pathogenesis of Alzheimer's disease. Recent studies suggest that A{beta} has important physiological roles in addition to its pathological roles. We recently demonstrated that A{beta}42 protects hippocampal neurons from glutamate-induced neurotoxicity, but the relationship between A{beta}42 assemblies and their neuroprotective effects remains largely unknown. In this study, we prepared non-fibrillar and fibrillar A{beta}42 based on the results of the thioflavin T assay, Western blot analysis, and atomic force microscopy, and examined the effects of non-fibrillar and fibrillar A{beta}42 on glutamate-induced neurotoxicity. Non-fibrillar A{beta}42, but not fibrillar A{beta}42, protected hippocampal neurons frommore » glutamate-induced neurotoxicity. Furthermore, non-fibrillar A{beta}42 decreased both neurotoxicity and increases in the intracellular Ca{sup 2+} concentration induced by N-methyl-D-aspartate (NMDA), but not by {alpha}-amino-3-hydrozy-5-methyl-4-isoxazole propionic acid (AMPA). Our results suggest that non-fibrillar A{beta}42 protects hippocampal neurons from glutamate-induced neurotoxicity through regulation of the NMDA receptor.« less

  5. Propofol effectively inhibits lithium-pilocarpine- induced status epilepticus in rats via downregulation of N-methyl-D-aspartate receptor 2B subunit expression

    PubMed Central

    Wang, Henglin; Wang, Zhuoqiang; Mi, Weidong; Zhao, Cong; Liu, Yanqin; Wang, Yongan; Sun, Haipeng

    2012-01-01

    Status epilepticus was induced via intraperitoneal injection of lithium-pilocarpine. The inhibitory effects of propofol on status epilepticus in rats were judged based on observation of behavior, electroencephalography and 24-hour survival rate. Propofol (12.5–100 mg/kg) improved status epilepticus in a dose-dependent manner, and significantly reduced the number of deaths within 24 hours of lithium-pilocarpine injection. Western blot results showed that, 24 hours after induction of status epilepticus, the levels of N-methyl-D-aspartate receptor 2A and 2B subunits were significantly increased in rat cerebral cortex and hippocampus. Propofol at 50 mg/kg significantly suppressed the increase in N-methyl-D-aspartate receptor 2B subunit levels, but not the increase in N-methyl-D-aspartate receptor 2A subunit levels. The results suggest that propofol can effectively inhibit status epilepticus induced by lithium-pilocarpine. This effect may be associated with downregulation of N-methyl-D-aspartate receptor 2B subunit expression after seizures. PMID:25737709

  6. An examination of the roles of glutamate and sex in latent inhibition: Relevance to the glutamate hypothesis of schizophrenia?

    PubMed

    Huang, Andrew Chih Wei; Bo-Han He, Alan; Chen, Chih-Chung

    2017-10-01

    The present study examined the effects of the glutamate receptor antagonist MK-801, the glutamate receptor agonist N-methyl-D-aspartate (NMDA), and sexual dimorphism on latent inhibition to elucidate the glutamate hypothesis of schizophrenia. During the pre-exposure phase, 56 male and 65 female Wistar rats were intracerebroventricularly administered normal saline, MK-801 or NMDA, in the left ventricle and then exposed to a passive avoidance box (or a different context) in three trials over 3 days. Then, all of the rats were placed in the light compartment of the passive avoidance box and were allowed to enter the dark compartment, where they each received a footshock (1mA, 2s) in five trials over 5 days. Injections of the glutamate drugs NMDA and MK-801 did not affect latent inhibition. Sexual dimorphism did not occur in latent inhibition. The present data on the male rats indicated that the glutamate system did not affect latent inhibition, indicating that the glutamate system was not like the dopamine system in terms of mediating the positive symptoms of schizophrenia. The glutamate system might be involved in the negative and cognitive symptoms of schizophrenia. The results may provide information for novel treatments of the negative and cognitive symptoms of schizophrenia. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. The effect of the mGlu5 negative allosteric modulator MTEP and NMDA receptor partial agonist D-cycloserine on Pavlovian conditioned fear.

    PubMed

    Handford, Charlotte E; Tan, Shawn; Lawrence, Andrew J; Kim, Jee Hyun

    2014-09-01

    The metabotropic glutamate receptor 5 (mGlu5) and N-methyl-D-aspartate (NMDA) receptor are critical for processes underlying synaptic plasticity, such as long-term potentiation. mGlu5 signaling increases neuronal excitability and potentiates NMDA receptor currents in the amygdala and the hippocampus. The present study examined the involvement of mGlu5 in the acquisition and consolidation of conditioned fear to a tone and context in mice, and explored the functional relationship between mGlu5 and NMDA receptors in this regard. Experiment 1 showed that systemic administration of the mGlu5 negative allosteric modulator 3-[(2-methyl-1,3-thiazol-4-yl)ethynyl]pyridine (MTEP) prior to conditioning significantly attenuated cue-elicited freezing during fear conditioning, which suggests that mGlu5 is necessary for the formation of a tone-shock association. This effect was dose-related (Experiment 2) and not due to any effects of MTEP on shock sensitivity or state-dependency (Experiment 3). Post-conditioning injection of MTEP had no effects (Experiment 4). Although post-conditioning injection of the NMDA receptor partial agonist D-cycloserine (DCS) alone facilitated consolidation of conditioned fear (Experiment 6), it was not able to rescue the acquisition deficit caused by MTEP (Experiment 5). Taken together, these findings indicate a crucial role for mGlu5 signaling in acquisition and NMDA receptor signaling in consolidation of conditioned fear.

  8. The Relationship Between the Renin-Angiotensin-Aldosterone System and NMDA Receptor-Mediated Signal and the Prevention of Retinal Ganglion Cell Death.

    PubMed

    Kobayashi, Mamoru; Hirooka, Kazuyuki; Ono, Aoi; Nakano, Yuki; Nishiyama, Akira; Tsujikawa, Akitaka

    2017-03-01

    Excitotoxicity, which is due to glutamate-induced toxic effects on the retinal ganglion cell (RGC), is one of several mechanisms of RGC loss. The renin-angiotensin-aldosterone system (RAAS) has also been implicated in RGC death. Therefore, it is important to determine the exact relationship between the RAAS and N-methyl-d-aspartate (NMDA) receptor-mediated signal in order to prevent RGC death. N-methyl-d-aspartate or aldosterone was injected into the vitreous body. After intravitreal injection of NMDA or aldosterone, animals were treated with spironolactone or memantine. Retinal damage was evaluated by measuring the number of RGCs at 4 weeks after local administration of aldosterone or at 2 weeks after local administration of NMDA. Vitreous humor levels of aldosterone were measured using enzyme immunoassay kits. A significantly decreased number of RGCs were observed after intravitreal injection of NMDA. Although spironolactone did not show any neuroprotective effects, memantine significantly reduced NMDA-induced degeneration in the retina. Furthermore, a significant decrease in the number of RGCs was observed after an intravitreal injection of aldosterone. While memantine did not exhibit any neuroprotective effects, spironolactone caused a significant reduction in the aldosterone-induced degeneration in the retina. There was no change in the aldosterone concentration in the vitreous humor after an NMDA injection. Our findings indirectly show that there is no relationship between the RAAS and NMDA receptor-mediated signal with regard to RGC death.

  9. Synthesis and characterization of a radiolabeled derivative of the phencyclidine/N-methyl-D-aspartate receptor ligand (+)MK-801 with high specific radioactivity

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Keana, J.F.W.; Scherz, M.W.; Quarum, M.

    1988-01-01

    A (/sup 3/H)-labelled derivative of the drug (+)MK-801 with a high specific radioactivity was synthesized by first preparing a tribromo derivative of (+)MK-801 followed by catalytic reduction in the presence of (/sup 3/H)-gas and subsequent purification of the radioactive product by reversed-phase high performance liquid chromatography (RP-HPLC). This resulted in pure (+) (/sup 3/H)MK-801 with a specific radioactivity of 97 Ci/mmol. The (+) (/sup 3/H)MK-801 was shown to interact with high affinity and selectivity with the phencyclidine (PCP) receptor in guinea pig brain membrane suspensions. The PCP receptor is associated with a cation channel that is chemically gated by glutamatemore » and N-methyl-D-aspartate (NMDA). Drugs that interact with the PCP receptor block this channel. The (+) (/sup 3/H)MK-801 described here will be useful to investigate the biochemistry of PCP/NMDA receptors in experiments where a high specific radioactivity is essential.« less

  10. Effect of the non-NMDA receptor antagonist GYKI 52466 on the microdialysate and tissue concentrations of amino acids following transient forebrain ischaemia.

    PubMed

    Arvin, B; Lekieffre, D; Graham, J L; Moncada, C; Chapman, A G; Meldrum, B S

    1994-04-01

    The effect of the non-N-methyl-D-aspartate (non-NMDA) receptor antagonist 1-(4-aminophenyl)-4-methyl-7,8-methylenedioxy-5H-2,3-benzodiazepine hydrochloride (GYKI 52466) on ischaemia-induced changes in the microdialysate and tissue concentrations of glutamate, aspartate, and gamma-aminobutyric acid (GABA) was studied in rats. Twenty minutes of four-vessel occlusion resulted in a transient increase in microdialysate levels of glutamate, aspartate, and GABA in striatum, cortex, and hippocampus. Administration of GYKI 52466 (10 mg/kg bolus + 10 mg/kg/60 min intravenously starting 20 min before onset of ischaemia) inhibited ischaemia-induced increases in microdialysate glutamate and GABA in striatum without affecting the increases in hippocampus or cortex. Twenty minutes of four-vessel occlusion resulted in immediate small decreases and larger delayed (72 h) decreases in tissue levels of glutamate and aspartate. Transient increases in tissue levels of GABA were shown in all three structures at the end of the ischaemic period. At 72 h, after the ischaemic period, significantly reduced GABA levels were observed in striatum and hippocampus. GYKI 52466, given under identical conditions as above, augmented the ischaemia-induced decrease in striatal tissue levels of glutamate and aspartate, without significantly affecting the decreases in hippocampus and cortex. Twenty minutes of ischaemia resulted in a large increase in microdialysate dopamine in striatum. GYKI 52466 failed to inhibit this increase. Kainic acid (500 microM infused through the probe for 20 min) caused increases in microdialysate glutamate and aspartate in the striatum. GYKI 52466 (10 mg/kg bolus + 10 mg/kg/60 min) completely inhibited the kainic acid-induced glutamate release. In conclusion, the action of the non-NMDA antagonist, GYKI 52466, in the striatum is different from that in the cortex and hippocampus. The inhibition by GYKI 52466 of ischaemia-induced and kainate-induced increases in microdialysate

  11. Effects of N-methyl-D-aspartate receptor ligands on sensitivity to reinforcer magnitude and delayed reinforcement in a delay-discounting procedure

    PubMed Central

    Yates, Justin R; Gunkel, Benjamin T; Rogers, Katherine K; Hughes, Mallory N; Prior, Nicholas A

    2016-01-01

    Rationale The N-methyl-D-aspartate (NMDA) receptor has been recently identified as an important mediator of impulsive choice, as assessed in delay discounting. Although discounting is independently influenced by sensitivity to reinforcer magnitude and delayed reinforcement, few studies have examined how NMDA receptor ligands differentially affect these parameters. Objectives The current study examined the effects of various NMDA receptor ligands on sensitivity to reinforcer magnitude and delayed reinforcement in a delay-discounting procedure. Methods Following behavioral training, rats received treatments of the following NMDA receptor ligands: the uncompetitive antagonists ketamine (0, 1.0, 5.0, or 10.0 mg/kg; i.p.), MK-801 (0, 0.003, 0.01, or 0.03 mg/kg; s.c.), and memantine (0, 2.5, 5.0, or 10.0 mg/kg; i.p.), the competitive antagonist CGS 19755 (0, 5.0, 10.0, or 20.0 mg/kg; s.c.), the non-competitive NR2B subunit-selective antagonist ifenprodil (0, 1.0, 3.0, or 10.0 mg/kg; i.p), and the partial agonist D-cycloserine (0, 3.25, 15.0, or 30.0 mg/kg; s.c.). Results When an exponential model was used to describe discounting, CGS 19755 (5.0 mg/kg) increased impulsive choice without altering sensitivity to reinforcer magnitude. Conversely, ketamine (10.0 mg/kg), memantine (5.0 mg/kg), and ifenprodil (10.0 mg/kg) decreased sensitivity to reinforcer magnitude without altering impulsive choice. MK-801 and D-cycloserine did not alter delay-discounting performance, although two-way ANOVA analyses indicated D-cycloserine (15.0 mg/kg) decreased impulsive choice. Conclusions The behavioral changes observed in delay discounting following administration of NMDA receptor antagonists do not always reflect an alteration in impulsive choice. These results emphasize the utility in employing quantitative methods to assess drug effects in delay discounting. PMID:27837332

  12. NO-producing compounds transform neuron responses to glutamate.

    PubMed

    D'yakonova, T L

    2000-01-01

    We have previously shown that NO increases the excitatory effects of glutamate and blocks the desensitization of neurons to glutamate in the brain of the common snail. The aim of the present work was to identify the possible effect of NO on inhibitory responses to glutamate in the neurons of this mollusk. Electrophysiological investigations were performed on three identified neurons. The results showed that glutamate (0.05-0.1 mM) initially induced hyperpolarization and blocked the spike activity of these neurons. Simultaneous exposure to glutamate and the NO donor nitroprusside or preincubation with an NO donor had the effect that cells again responded to glutamate with depolarization and excitation. The transformed excitatory response lasted several minutes and could be reproduced even after 24 h of washing. The NO synthase blocker monomethylarginine blocked the excitatory response to glutamate. Another agonist of glutamate receptors, N-methyl-D-aspartate (NMDA, 0.1-1 mM), initially had excitatory effects on these neurons; this effect was significantly enhanced after transformation of the response to glutamate by NO donors. The results obtained here show that NO is involved in transforming the inhibitory responses to glutamate to excitatory responses, and that this effect may be mediated by NMDA-type receptors.

  13. Glutamate and GABA in lateral hypothalamic mechanisms controlling food intake.

    PubMed

    Stanley, B G; Urstadt, K R; Charles, J R; Kee, T

    2011-07-25

    By the 1990s a convergence of evidence had accumulated to suggest that neurons within the lateral hypothalamus (LH) play important roles in the stimulation of feeding behavior. However, there was little direct evidence demonstrating that neurotransmitters in the LH could, like electrical stimulation, elicit feeding in satiated animals. The present paper is a brief review in honor of Bartley Hoebel's scientific contributions, emphasizing the evidence from my lab that the excitatory neurotransmitter glutamate and the inhibitory neurotransmitter gamma aminobutyric acid (GABA) in the LH mediate feeding stimulation and feeding inhibition respectively. Specifically, we summarize evidence that LH injection of glutamate, or agonists of its N-methyl-D-aspartate (NMDA) and non-NMDA receptors, elicits feeding in satiated rats, that NMDA receptor antagonists block the eating elicited by NMDA and, more importantly, that NMDA blockade suppresses natural feeding and can reduce body weight. Conversely, GABA(A) agonists injected into the LH suppress feeding and can also reduce body weight, while GABA(A) receptor antagonists actually elicit eating when injected into the LH of satiated rats. It is suggested that natural feeding may reflect the moment-to-moment balance in the activity of glutamate and GABA within the LH. Copyright © 2011 Elsevier Inc. All rights reserved.

  14. Immunohistochemical localization of ionotropic glutamate receptors in the rat red nucleus

    PubMed Central

    Minbay, Zehra; Kocoglu, Sema Serter; Yurtseven, Duygu Gok; Eyigor, Ozhan

    2017-01-01

    In this study, we aimed to determine the presence as well as the diverse distribution of N-methyl-D-aspartate (NMDA) and non-NMDA glutamate receptor subunits in the rat red nucleus. Using adult Sprague-Dawley rats as the experimental animals, immunohistochemistry was performed on 30 µm thick coronal brain sections with antibodies against α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (GluA1-4), kainate (GluK1, GluK2/3, and GluK5), and NMDA (GluN1 and GluN2A) receptor subunits. The results showed that all ionotropic glutamate receptor subunits are expressed in the red nucleus. Specific staining was localized in the neuron bodies and processes. However, the pattern of immunoreactivity and the number of labeled neurons changed depending on the type of ionotropic glutamate receptor subunits and the localization of neurons in the red nucleus. The neurons localized in the magnocellular part of the red nucleus were particularly immunopositive for GluA2, GluA4, GluK2/3, GluK5, GluN1, and GluN2A receptor proteins. In the parvocellular part of the red nucleus, ionotropic glutamate receptor subunit immunoreactivity of variable intensity (lightly to moderately stained) was detected in the neurons. These results suggest that red nucleus neurons in rat heterogeneously express ionotropic glutamate receptor subunits to form functional receptor channels. In addition, the likelihood of the coexpression of different subunits in the same subgroup of neurons suggests the formation of receptor channels with diverse structure by way of different subunit combination, and the possibility of various neuronal functions through these channels in the red nucleus. PMID:28027456

  15. Immunohistochemical localization of ionotropic glutamate receptors in the rat red nucleus.

    PubMed

    Minbay, Zehra; Serter Kocoglu, Sema; Gok Yurtseven, Duygu; Eyigor, Ozhan

    2017-02-21

    In this study, we aimed to determine the presence as well as the diverse distribution of N-methyl-D-aspartate (NMDA) and non-NMDA glutamate receptor subunits in the rat red nucleus. Using adult Sprague-Dawley rats as the experimental animals, immunohistochemistry was performed on 30 µm thick coronal brain sections with antibodies against α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (GluA1-4), kainate (GluK1, GluK2/3, and GluK5), and NMDA (GluN1 and GluN2A) receptor subunits. The results showed that all ionotropic glutamate receptor subunits are expressed in the red nucleus. Specific staining was localized in the neuron bodies and processes. However, the pattern of immunoreactivity and the number of labeled neurons changed depending on the type of ionotropic glutamate receptor subunits and the localization of neurons in the red nucleus. The neurons localized in the magnocellular part of the red nucleus were particularly immunopositive for GluA2, GluA4, GluK2/3, GluK5, GluN1, and GluN2A receptor proteins. In the parvocellular part of the red nucleus, ionotropic glutamate receptor subunit immunoreactivity of variable intensity (lightly to moderately stained) was detected in the neurons. These results suggest that red nucleus neurons in rat heterogeneously express ionotropic glutamate receptor subunits to form functional receptor channels. In addition, the likelihood of the coexpression of different subunits in the same subgroup of neurons suggests the formation of receptor channels with diverse structure by way of different subunit combination, and the possibility of various neuronal functions through these channels in the red nucleus.

  16. Sub-acute administration of benzo[a]pyrene (B[a]P) reduces anxiety-related behaviour in adult mice and modulates regional expression of N-methyl-D-aspartate (NMDA) receptors genes in relevant brain regions.

    PubMed

    Grova, Nathalie; Schroeder, Henri; Farinelle, Sophie; Prodhomme, Emmanuel; Valley, Anne; Muller, Claude P

    2008-08-01

    Abnormal glutamatergic transmission caused by modulation of N-methyl-D-aspartate (NMDA) receptors was demonstrated in animal models chronically exposed to various organic micropollutants. Recent developments in neurobiology have implicated these receptors in the regulation of anxiety. In order to investigate anxiety-related effects of benzo[a]pyrene (B[a]P), Balb/c mice were sub-acutely exposed to B[a]P (0.02-200 mg kg(-1) day(-1), 10 days, i.p.). Their performance was tested in the elevated-plus maze and the hole-board apparatus and the NMDA receptor expression genes (NR1, 2A and 2B subunits) was measured in eight brain regions. Mice treated with 20-200 mg kg(-1) B[a]P showed a disproportionate accumulation of B[a]P and its metabolites (in particular, the toxic 7,8-diol-B[a]P) in the blood and even more in the brain. These mice were less anxious than controls in the hole-board test and the elevated-plus maze. This observation was associated with an overexpression of the NMDA NR1 receptor gene and concomitant decreases of the NR2A and NR2B subunits expression in the hippocampus, the hypothalamus and the cerebellum. In the temporal cortex, a significant dose-related decrease of NR2A was observed whereas the other subunits remained unchanged. In conclusion, a sub-acute exposure to B[a]P (20 and 200 mg kg(-1)) reduced anxiety-related behaviour in adult mice and concomitantly impaired NMDA receptor gene expression in relevant brain regions.

  17. Abeta oligomers induce neuronal oxidative stress through an N-methyl-D-aspartate receptor-dependent mechanism that is blocked by the Alzheimer drug memantine.

    PubMed

    De Felice, Fernanda G; Velasco, Pauline T; Lambert, Mary P; Viola, Kirsten; Fernandez, Sara J; Ferreira, Sergio T; Klein, William L

    2007-04-13

    Oxidative stress is a major aspect of Alzheimer disease (AD) pathology. We have investigated the relationship between oxidative stress and neuronal binding of Abeta oligomers (also known as ADDLs). ADDLs are known to accumulate in brain tissue of AD patients and are considered centrally related to pathogenesis. Using hippocampal neuronal cultures, we found that ADDLs stimulated excessive formation of reactive oxygen species (ROS) through a mechanism requiring N-methyl-d-aspartate receptor (NMDA-R) activation. ADDL binding to neurons was reduced and ROS formation was completely blocked by an antibody to the extracellular domain of the NR1 subunit of NMDA-Rs. In harmony with a steric inhibition of ADDL binding by NR1 antibodies, ADDLs that were bound to detergent-extracted synaptosomal membranes co-immunoprecipitated with NMDA-R subunits. The NR1 antibody did not affect ROS formation induced by NMDA, showing that NMDA-Rs themselves remained functional. Memantine, an open channel NMDA-R antagonist prescribed as a memory-preserving drug for AD patients, completely protected against ADDL-induced ROS formation, as did other NMDA-R antagonists. Memantine and the anti-NR1 antibody also attenuated a rapid ADDL-induced increase in intraneuronal calcium, which was essential for stimulated ROS formation. These results show that ADDLs bind to or in close proximity to NMDA-Rs, triggering neuronal damage through NMDA-R-dependent calcium flux. This response provides a pathologically specific mechanism for the therapeutic action of memantine, indicates a role for ROS dysregulation in ADDL-induced cognitive impairment, and supports the unifying hypothesis that ADDLs play a central role in AD pathogenesis.

  18. Periventricular anteroventral third ventricle lesions diminish the pressor response produced by systemic injection of the N-methyl-D-aspartate receptor antagonist MK-801

    NASA Technical Reports Server (NTRS)

    Whalen, E. J.; Beltz, T. G.; Lewis, S. J.; Johnson, A. K.

    1999-01-01

    This study examined whether electrolytic ablation of the periventricular anteroventral third ventricle (AV3V) would affect the increases in mean arterial blood pressure (MAP) and heart rate (HR) in conscious rats produced by systemic injection of the centrally acting N-methyl-D-aspartate (NMDA) receptor ion-channel blocker, (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5, 10-imine (MK-801; 250 microgram/kg, i.v.). MK-801 produced a smaller increase in MAP in rats with AV3V lesions than in sham-lesion rats (+36+/-2% vs. +52+/-5%, respectively, P<0.05). In contrast, MK-801 produced similar increases in HR in the AV3V- and sham-lesion rats (+28+/-3% vs. +22+/-4%, respectively, P>0.05). These findings demonstrate that the MK-801-induced pressor response is dependent upon the integrity of the AV3V region, whereas the MK-801-induced tachycardia is not. Copyright 1999 Elsevier Science B.V.

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

    PubMed Central

    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 Mg2+ 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

  20. N-methyl-D-aspartate receptors and large conductance calcium-sensitive potassium channels inhibit the release of opioid peptides that induce mu-opioid receptor internalization in the rat spinal cord.

    PubMed

    Song, B; Marvizón, J C G

    2005-01-01

    Endogenous opioids in the spinal cord play an important role in nociception, but the mechanisms that control their release are poorly understood. To simultaneously detect all opioids able to activate the mu-opioid receptor, we measured mu-opioid receptor internalization in rat spinal cord slices stimulated electrically or chemically to evoke opioid release. Electrical stimulation of the dorsal horn in the presence of peptidase inhibitors produced mu-opioid receptor internalization in half of the mu-opioid receptor neurons. This internalization was rapidly abolished by N-methyl-D-aspartate (IC50=2 microM), and N-methyl-D-aspartate antagonists prevented this effect. mu-Opioid receptor internalization evoked by high K+ or veratridine was also inhibited by N-methyl-D-aspartate receptor activation. N-methyl-D-aspartate did not affect mu-opioid receptor internalization induced by exogenous endomorphins, confirming that the effect of N-methyl-D-aspartate was on opioid release. We hypothesized that this inhibition was mediated by large conductance Ca2+-sensitive K+ channels BK(Ca2+). Indeed, inhibition by N-methyl-D-aspartate was prevented by tetraethylammonium and by the selective BK(Ca2+) blockers paxilline, penitrem A and verruculogen. Paxilline did not increase mu-opioid receptor internalization in the absence of N-methyl-D-aspartate, indicating that it does not produce an increase in opioid release unrelated to the inhibition by N-methyl-d-aspartate. The BK(Ca2+) involved appears to be a subtype with slow association kinetics for iberiotoxin, which was effective only with long incubations. The BK(Ca2+) opener NS-1619 also inhibited the evoked mu-opioid receptor internalization, and iberiotoxin prevented this effect. We concluded that Ca2+ influx through N-methyl-D-aspartate receptors causes the opening of BK(Ca2+) and hyperpolarization in opioid-containing dorsal horn neurons, resulting in the inhibition of opioid release. Since mu-opioid receptors in the dorsal horn

  1. N-METHYL-d-ASPARTATE RECEPTORS AND LARGE CONDUCTANCE CALCIUM-SENSITIVE POTASSIUM CHANNELS INHIBIT THE RELEASE OF OPIOID PEPTIDES THAT INDUCE μ-OPIOID RECEPTOR INTERNALIZATION IN THE RAT SPINAL CORD

    PubMed Central

    SONG, B.; MARVIZÓN, J. C. G.

    2006-01-01

    Endogenous opioids in the spinal cord play an important role in nociception, but the mechanisms that control their release are poorly understood. To simultaneously detect all opioids able to activate the μ-opioid receptor, we measured μ-opioid receptor internalization in rat spinal cord slices stimulated electrically or chemically to evoke opioid release. Electrical stimulation of the dorsal horn in the presence of peptidase inhibitors produced μ-opioid receptor internalization in half of the μ-opioid receptor neurons. This internalization was rapidly abolished by N-methyl-d-aspartate (IC50=2 μM), and N-methyl-d-aspartate antagonists prevented this effect. μ-Opioid receptor internalization evoked by high K+ or veratridine was also inhibited by N-methyl-d-aspartate receptor activation. N-methyl-d-aspartate did not affect μ-opioid receptor internalization induced by exogenous endomorphins, confirming that the effect of N-methyl-d-aspartate was on opioid release. We hypothesized that this inhibition was mediated by large conductance Ca2+-sensitive K+ channels BK(Ca2+). Indeed, inhibition by N-methyl-d-aspartate was prevented by tetraethylammonium and by the selective BK(Ca2+) blockers paxilline, penitrem A and verruculogen. Paxilline did not increase μ-opioid receptor internalization in the absence of N-methyl-d-aspartate, indicating that it does not produce an increase in opioid release unrelated to the inhibition by N-methyl-d-aspartate. The BK(Ca2+) involved appears to be a subtype with slow association kinetics for iberiotoxin, which was effective only with long incubations. The BK(Ca2+) opener NS-1619 also inhibited the evoked μ-opioid receptor internalization, and iberiotoxin prevented this effect. We concluded that Ca2+ influx through N-methyl-d-aspartate receptors causes the opening of BK(Ca2+) and hyperpolarization in opioid-containing dorsal horn neurons, resulting in the inhibition of opioid release. Since μ-opioid receptors in the dorsal horn

  2. Glycine aggravates ischemia reperfusion-induced acute kidney injury through N-Methyl-D-Aspartate receptor activation in rats.

    PubMed

    Arora, Shiyana; Kaur, Tajpreet; Kaur, Anudeep; Singh, Amrit Pal

    2014-08-01

    The present study was designed to investigate the role of glycine in ischemia reperfusion-induced acute kidney injury (AKI) in rats. The AKI was induced in rats by occluding renal pedicles for 40 min followed by reperfusion for 24 h. The AKI was assessed by measuring creatinine clearance, blood urea nitrogen, plasma uric acid, potassium, fractional excretion of sodium, and microproteinuria. The oxidative stress in renal tissues was assessed by quantification of myeloperoxidase activity, thiobarbituric acid-reactive substances, superoxide anion generation, and reduced glutathione level. Glycine (100, 200, and 400 mg/kg, i.p.) was administered to rats 30 min before subjecting to AKI. The glycinergic receptor blocker, strychnine (0.75 mg/kg i.p.), and glycine-binding site blocker at N-methyl-D-aspartate (NMDA) receptor, kynurenic acid (300 and 600 mg/kg i.p.), were used in the present study. The ischemia reperfusion induced AKI as witnessed by significant change in plasma, urinary, and tissue parameters employed in the present study. Glycine treatment increased ischemia reperfusion-induced AKI. The treatment with strychnine did not show any protection, whereas kynurenic acid ameliorated renal ischemia reperfusion-induced AKI. The results obtained in present study suggest that glycine increases ischemia reperfusion-induced renal damage through NMDA receptor agonism rather than strychnine-sensitive glycinergic receptors. Hence, it is concluded that glycine aggravates ischemia reperfusion-induced AKI. In addition, the activation of strychnine-insensitive glycine-binding site of NMDA receptors is responsible for its renal-damaging effect rather than strychnine-sensitive glycinergic receptors.

  3. Clinically significant response to zolpidem in disorders of consciousness secondary to anti-N-methyl-D-aspartate receptor encephalitis in a teenager: a case report.

    PubMed

    Appu, Merveen; Noetzel, Michael

    2014-03-01

    Anti-N-methyl-d-aspartate receptor encephalitis has been associated with a prolonged neuropsychiatric phase that may last for months to years. We report the case of a 16-year-old girl who was diagnosed with anti-N-methyl-d-aspartate receptor encephalitis resulting from left ovarian mature teratoma 2 weeks after presentation with psychosis. Following tumor removal and immunotherapy, recovery from a minimally conscious state was accelerated significantly by zolpidem that was used for her sleep disturbance. Our patient was discharged home 8 weeks after admission with marked improvement in her neurological function. Zolpidem has been reported to improve arousal in disorders of consciousness but there are no previous reports of its benefit among patients with anti-N-methyl-d-aspartate receptor encephalitis. Zolpidem would be a reasonable consideration as an adjunctive treatment in anti-N-methyl-d-aspartate receptor encephalitis after tumor removal and immunotherapy to accelerate recovery and rehabilitation. Copyright © 2014 Elsevier Inc. All rights reserved.

  4. Evaluation of the role of NMDA receptor function in antidepressant-like activity. A new study with citalopram and fluoxetine in the forced swim test in mice.

    PubMed

    Wolak, Małgorzata; Siwek, Agata; Szewczyk, Bernadeta; Poleszak, Ewa; Bystrowska, Beata; Moniczewski, Andrzej; Rutkowska, Anita; Młyniec, Katarzyna; Nowak, Gabriel

    2015-06-01

    The NMDA/glutamate receptors are involved in the mechanism of antidepressant activity. The present study was designed to investigate the effect of NMDA receptor ligands (agonists and antagonists of glutamate sites) on the antidepressant-like activity of selective serotonin reuptake inhibitors (SSRIs), citalopram and fluoxetine, in the forced swim test in mice. The antidepressant activity (reduction in immobility time) of citalopram but not of fluoxetine was antagonized by N-methyl-D-aspartate acid and enhanced by CGP37849 (antagonist of the NMDA receptor). The present literature data indicate that the antidepressant-like activity of conventional antidepressants is generally affected by the NMDA receptor, although by modulation from different sites of the complex. Thus, it supports the issue of the ability of NMDA receptor antagonists to enhance the antidepressant action in human depression. Copyright © 2014 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.

  5. N-methyl-D-aspartate receptor antagonist effects on prefrontal cortical connectivity better model early than chronic schizophrenia.

    PubMed

    Anticevic, Alan; Corlett, Philip R; Cole, Michael W; Savic, Aleksandar; Gancsos, Mark; Tang, Yanqing; Repovs, Grega; Murray, John D; Driesen, Naomi R; Morgan, Peter T; Xu, Ke; Wang, Fei; Krystal, John H

    2015-03-15

    Prefrontal cortex (PFC) function contributes to schizophrenia onset and progression. However, little is known about neural mechanisms behind PFC functional alterations along illness stages. Recent pharmacologic studies indicate that glutamate dysfunction may produce increased functional connectivity. However, pharmacologic models of schizophrenia overlook effects of illness progression on PFC function. This study compared N-methyl-D-aspartate glutamate receptor (NMDAR) antagonist effects in healthy volunteers with stages of schizophrenia with respect to PFC functional connectivity. First, we tested ketamine effects on PFC functional connectivity in healthy volunteers in a data-driven way (n = 19). Next, we compared healthy subjects (n = 96) with three clinical groups: individuals at high risk for schizophrenia (n = 21), people early in their course of schizophrenia (EC-SCZ) (n = 28), and patients with chronic illness (n = 20). Across independent analyses, we used data-driven global brain connectivity techniques restricted to PFC to identify functional dysconnectivity. Results revealed robust PFC hyperconnectivity in healthy volunteers administered ketamine (Cohen's d = 1.46), resembling individuals at high risk for schizophrenia and EC-SCZ. Hyperconnectivity was not found in patients with chronic illness relative to EC-SCZ patients. Results provide the first evidence that ketamine effects on PFC functional connectivity resemble early course but not chronic schizophrenia. Results suggest an illness phase-specific relevance of NMDAR antagonist administration for prefrontal dysconnectivity associated with schizophrenia. This finding has implications for the neurobiology of illness progression and for the widespread use of NMDAR antagonists in the development of therapeutics for schizophrenia. Copyright © 2015. Published by Elsevier Inc.

  6. Decreased free d-aspartate levels are linked to enhanced d-aspartate oxidase activity in the dorsolateral prefrontal cortex of schizophrenia patients.

    PubMed

    Nuzzo, Tommaso; Sacchi, Silvia; Errico, Francesco; Keller, Simona; Palumbo, Orazio; Florio, Ermanno; Punzo, Daniela; Napolitano, Francesco; Copetti, Massimiliano; Carella, Massimo; Chiariotti, Lorenzo; Bertolino, Alessandro; Pollegioni, Loredano; Usiello, Alessandro

    2017-01-01

    It is long acknowledged that the N -methyl d-aspartate receptor co-agonist, d-serine, plays a crucial role in several N -methyl d-aspartate receptor-mediated physiological and pathological processes, including schizophrenia. Besides d-serine, another free d-amino acid, d-aspartate, is involved in the activation of N -methyl d-aspartate receptors acting as an agonist of this receptor subclass, and is abundantly detected in the developing human brain. Based on the hypothesis of N -methyl d-aspartate receptor hypofunction in the pathophysiology of schizophrenia and considering the ability of d-aspartate and d-serine to stimulate N -methyl d-aspartate receptor-dependent transmission, in the present work we assessed the concentration of these two d-amino acids in the post-mortem dorsolateral prefrontal cortex and hippocampus of patients with schizophrenia and healthy subjects. Moreover, in this cohort of post-mortem brain samples we investigated the spatiotemporal variations of d-aspartate and d-serine. Consistent with previous work, we found that d-aspartate content was selectively decreased by around 30% in the dorsolateral prefrontal cortex, but not in the hippocampus, of schizophrenia-affected patients, compared to healthy subjects. Interestingly, such selective reduction was associated to greater (around 25%) cortical activity of the enzyme responsible for d-aspartate catabolism, d-aspartate oxidase. Conversely, no significant changes were found in the methylation state and transcription of DDO gene in patients with schizophrenia, compared to control individuals, as well as in the expression levels of serine racemase, the major enzyme responsible for d-serine biosynthesis, which also catalyzes aspartate racemization. These results reveal the potential involvement of altered d-aspartate metabolism in the dorsolateral prefrontal cortex as a factor contributing to dysfunctional N -methyl d-aspartate receptor-mediated transmission in schizophrenia.

  7. Dephosphorylation of GluN2B C-Terminal Tyrosine Residues Does Not Contribute to Acute Ethanol Inhibition of Recombinant NMDA Receptors

    PubMed Central

    Hughes, Benjamin A.; Smothers, Corigan T.; Woodward, John J.

    2013-01-01

    N-methyl-D-aspartate (NMDA) receptors are ion channels activated by the neurotransmitter glutamate and are highly expressed by neurons. These receptors are critical for excitatory synaptic signaling and inhibition of NMDA receptors leads to impaired cognition and learning. Ethanol inhibits NMDA currents at concentrations associated with intoxication and this action may underlie some of the behavioral effects of ethanol. Although numerous sites and mechanisms of action have been tested, the manner in which ethanol inhibits NMDA receptors remains unclear. Recent findings in the literature suggest that ethanol, via facilitation of tyrosine phosphatase activity, may dephosphorylate key tyrosine residues in the C-terminus of GluN2B subunits resulting in diminished channel function. To directly test this hypothesis, we engineered GluN2B mutants that contained phenylalanine in place of tyrosine at three different sites and transiently expressed them with the GluN1 subunit in human embryonic kidney (HEK) cells. Whole-cell patch clamp electrophysiology was used to record glutamate-activated currents in the absence and presence of ethanol (10–600 mM). All mutants were functional and did not differ from one another with respect to current amplitude, steady-state to peak ratio, or magnesium block. Analysis of ethanol dose-response curves showed no significant difference in IC50 values between wild-type receptors and Y1252F, Y1336F, Y1472F or triple Y-F mutants. These findings suggest that dephosphorylation of C-terminal tyrosine residues does not account for ethanol inhibition of GluN2B receptors. PMID:23357553

  8. The role of striatal NMDA receptors in drug addiction.

    PubMed

    Ma, Yao-Ying; Cepeda, Carlos; Cui, Cai-Lian

    2009-01-01

    The past decade has witnessed an impressive accumulation of evidence indicating that the excitatory amino acid glutamate and its receptors, in particular the N-methyl-D-aspartate (NMDA) receptor subtype, play an important role in drug addiction. Various lines of research using animal models of drug addiction have demonstrated that drug-induced craving is accompanied by significant upregulation of NR2B subunit expression. Furthermore, selective blockade of NR2B-containing NMDA receptors in the striatum, especially in the nucleus accumbens (NAc) can inhibit drug craving and reinstatement. The purpose of this review is to examine the role of striatal NMDA receptors in drug addiction. After a brief description of glutamatergic innervation and NMDA receptor subunit distribution in the striatum, we discuss potential mechanisms to explain the role of striatal NMDA receptors in drug addiction by elucidating signaling cascades involved in the regulation of subunit expression and redistribution, phosphorylation of receptor subunits, as well as activation of intracellular signals triggered by drug experience. Understanding the mechanisms regulating striatal NMDA receptor changes in drug addiction will provide more specific and rational targets to counteract the deleterious effects of drug addiction.

  9. 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

  10. Altered Levels of Zinc and N-methyl-D-aspartic Acid Receptor Underlying Multiple Organ Dysfunctions After Severe Trauma

    PubMed Central

    Wang, Guanghuan; Yu, Xiaojun; Wang, Dian; Xu, Xiaohu; Chen, Guang; Jiang, Xuewu

    2015-01-01

    Background Severe trauma can cause secondary multiple organ dysfunction syndrome (MODS) and death. Oxidative stress and/or excitatory neurotoxicity are considered as the final common pathway in nerve cell injuries. Zinc is the cofactor of the redox enzyme, and the effect of the excitatory neurotoxicity is related to N-methyl-D-aspartic acid receptor (NMDAR). Material/Methods We investigated the levels of zinc and brainstem NMDAR in a rabbit model of severe trauma. Zinc and serum biochemical profiles were determined. Immunohistochemistry was used to detect brainstem N-methyl-D-aspartic acid receptor 1 (NR1), N-methyl-D-aspartic acid receptor 2A (NR2A), and N-methyl-D-aspartic acid receptor 2B (NR2B) expression. Results Brain and brainstem Zn levels increased at 12 h, but serum Zn decreased dramatically after the trauma. NR1 in the brainstem dorsal regions increased at 6 h after injury and then decreased. NR2A in the dorsal regions decreased to a plateau at 12 h after trauma. The levels of NR2B were lowest in the death group in the brainstem. Serum zinc was positively correlated with NR2A and 2B and negatively correlated with zinc in the brain. Correlations were also found between the brainstem NR2A and that of the dorsal brainstem, as well as between brainstem NR2A and changes in NR2B. There was a negative correlation between zinc and NR2A. Conclusions Severe trauma led to an acute reduction of zinc enhancing oxidative stress and the changes of NMDAR causing the neurotoxicity of the nerve cells. This may be a mechanism for the occurrence of MODS or death after trauma. PMID:26335029

  11. Role of NMDA receptor GluN2D subunit in the antidepressant effects of enantiomers of ketamine.

    PubMed

    Ide, Soichiro; Ikekubo, Yuiko; Mishina, Masayoshi; Hashimoto, Kenji; Ikeda, Kazutaka

    2017-11-01

    We investigated the rapid and sustained antidepressant effects of enantiomers of ketamine in N-methyl-d-aspartate (NMDA) receptor GluN2D subunit knockout (GluN2D-KO) mice. Intraperitoneal administration of ketamine or its enantiomers 10 min before the tail-suspension test exerted significant antidepressant effects on restraint stress-induced depression in both wildtype and GluN2D-KO mice. The antidepressant effects of (RS)-ketamine and (S)-ketamine were sustained 96 h after the injection in both wildtype and GluN2D-KO mice, but such sustained antidepressant effects of (R)-ketamine were only observed in wildtype mice. These data suggest that the GluN2D subunit is critical for the sustained antidepressant effects of (R)-ketamine. Copyright © 2017 The Authors. Production and hosting by Elsevier B.V. All rights reserved.

  12. Modulating the Intrinsic Disorder in the Cytoplasmic Domain Alters the Biological Activity of the N-Methyl-d-aspartate-sensitive Glutamate Receptor*

    PubMed Central

    Choi, Ucheor B.; Kazi, Rashek; Stenzoski, Natalie; Wollmuth, Lonnie P.; Uversky, Vladimir N.; Bowen, Mark E.

    2013-01-01

    The NMDA-sensitive glutamate receptor is a ligand-gated ion channel that mediates excitatory synaptic transmission in the nervous system. Extracellular zinc allosterically regulates the NMDA receptor by binding to the extracellular N-terminal domain, which inhibits channel gating. Phosphorylation of the intrinsically disordered intracellular C-terminal domain alleviates inhibition by extracellular zinc. The mechanism for this functional effect is largely unknown. Proline is a hallmark of intrinsic disorder, so we used proline mutagenesis to modulate disorder in the cytoplasmic domain. Proline depletion selectively uncoupled zinc inhibition with little effect on receptor biogenesis, surface trafficking, or ligand-activated gating. Proline depletion also reduced the affinity for a PDZ domain involved in synaptic trafficking and affected small molecule binding. To understand the origin of these phenomena, we used single molecule fluorescence and ensemble biophysical methods to characterize the structural effects of proline mutagenesis. Proline depletion did not eliminate intrinsic disorder, but the underlying conformational dynamics were changed. Thus, we altered the form of intrinsic disorder, which appears sufficient to affect the biological activity. These findings suggest that conformational dynamics within the intrinsically disordered cytoplasmic domain are important for the allosteric regulation of NMDA receptor gating. PMID:23782697

  13. Dynamic transition of neuronal firing induced by abnormal astrocytic glutamate oscillation

    NASA Astrophysics Data System (ADS)

    Li, Jiajia; Tang, Jun; Ma, Jun; Du, Mengmeng; Wang, Rong; Wu, Ying

    2016-08-01

    The gliotransmitter glutamate released from astrocytes can modulate neuronal firing by activating neuronal N-methyl-D-aspartic acid (NMDA) receptors. This enables astrocytic glutamate(AG) to be involved in neuronal physiological and pathological functions. Based on empirical results and classical neuron-glial “tripartite synapse” model, we propose a practical model to describe extracellular AG oscillation, in which the fluctuation of AG depends on the threshold of calcium concentration, and the effect of AG degradation is considered as well. We predict the seizure-like discharges under the dysfunction of AG degradation duration. Consistent with our prediction, the suppression of AG uptake by astrocytic transporters, which operates by modulating the AG degradation process, can account for the emergence of epilepsy.

  14. Phenformin suppresses calcium responses to glutamate and protects hippocampal neurons against excitotoxicity.

    PubMed

    Lee, Jaewon; Chan, Sic L; Lu, Chengbiao; Lane, Mark A; Mattson, Mark P

    2002-05-01

    Phenformin is a biguanide compound that can modulate glucose metabolism and promote weight loss and is therefore used to treat patients with type-2 diabetes. While phenformin may indirectly affect neurons by changing peripheral energy metabolism, the possibility that it directly affects neurons has not been examined. We now report that phenformin suppresses responses of hippocampal neurons to glutamate and decreases their vulnerability to excitotoxicity. Pretreatment of embryonic rat hippocampal cell cultures with phenformin protected neurons against glutamate-induced death, which was correlated with reduced calcium responses to glutamate. Immunoblot analyses showed that levels of the N-methyl-d-aspartate (NMDA) subunits NR1 and NR2A were significantly decreased in neurons exposed to phenformin, whereas levels of the AMPA receptor subunit GluR1 were unchanged. Whole-cell patch clamp analyses revealed that NMDA-induced currents were decreased, and AMPA-induced currents were unchanged in neurons pretreated with phenformin. Our data demonstrate that phenformin can protect neurons against excitotoxicity by differentially modulating levels of NMDA receptor subunits in a manner that decreases glutamate-induced calcium influx. These findings show that phenformin can modulate neuronal responses to glutamate, and suggest possible use of phenformin and related compounds in the prevention and/or treatment of neurodegenerative conditions. Copyright 2002 Elsevier Science (USA).

  15. N-aryl piperazine metabotropic glutamate receptor 5 positive allosteric modulators possess efficacy in preclinical models of NMDA hypofunction and cognitive enhancement.

    PubMed

    Gregory, K J; Herman, E J; Ramsey, A J; Hammond, A S; Byun, N E; Stauffer, S R; Manka, J T; Jadhav, S; Bridges, T M; Weaver, C D; Niswender, C M; Steckler, T; Drinkenburg, W H; Ahnaou, A; Lavreysen, H; Macdonald, G J; Bartolomé, J M; Mackie, C; Hrupka, B J; Caron, M G; Daigle, T L; Lindsley, C W; Conn, P J; Jones, C K

    2013-11-01

    Impaired transmission through glutamatergic circuits has been postulated to play a role in the underlying pathophysiology of schizophrenia. Furthermore, inhibition of the N-methyl-d-aspartate (NMDA) subtype of ionotropic glutamate receptors (NMDAR) induces a syndrome that recapitulates many of the symptoms observed in patients with schizophrenia. Selective activation of metabotropic glutamate receptor subtype 5 (mGlu5) may provide a novel therapeutic approach for treatment of symptoms associated with schizophrenia through facilitation of transmission through central glutamatergic circuits. Here, we describe the characterization of two novel N-aryl piperazine mGlu5 positive allosteric modulators (PAMs): 2-(4-(2-(benzyloxy)acetyl)piperazin-1-yl)benzonitrile (VU0364289) and 1-(4-(2,4-difluorophenyl)piperazin-1-yl)-2-((4-fluorobenzyl)oxy)ethanone (DPFE). VU0364289 and DPFE induced robust leftward shifts in the glutamate concentration-response curves for Ca(2+) mobilization and extracellular signal-regulated kinases 1 and 2 phosphorylation. Both PAMs displayed micromolar affinity for the common mGlu5 allosteric binding site and high selectivity for mGlu5. VU0364289 and DPFE possessed suitable pharmacokinetic properties for dosing in vivo and produced robust dose-related effects in reversing amphetamine-induced hyperlocomotion, a preclinical model predictive of antipsychotic-like activity. In addition, DPFE enhanced acquisition of contextual fear conditioning in rats and reversed behavioral deficits in a mouse model of NMDAR hypofunction. In contrast, DPFE had no effect on reversing apomorphine-induced disruptions of prepulse inhibition of the acoustic startle reflex. These mGlu5 PAMs also increased monoamine levels in the prefrontal cortex, enhanced performance in a hippocampal-mediated memory task, and elicited changes in electroencephalogram dynamics commensurate with procognitive effects. Collectively, these data support and extend the role for the development of

  16. Role of hydrogen bonding in ligand interaction with the N-methyl-D-aspartate receptor ion channel

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Leeson, P.D.; Carling, R.W.; James, K.

    1990-05-01

    Displacement of (3H)MK-801 (dizocilpine, 1) binding to rat brain membranes has been used to evaluate the affinities of novel dibenzocycloalkenimines related to 1 for the ion channel binding site (also known as the phencyclidine or PCP receptor) on the N-methyl-D-aspartate (NMDA) subtype of excitory amino acid receptor. In common with many other agents having actions in the central nervous system, these compounds contain a hydrophobic aromatic moiety and a basic nitrogen atom. The conformational rigidity of these ligands provides a unique opportunity to evaluate the importance of specific geometrical properties that influence active-site recognition, in particular the role of themore » nitrogen atom in hydrogen-bonding interactions. The relative affinities (IC50s) of hydrocarbon-substituted analogues of 1 and ring homologated cyclooctenimines illustrate the importance of size-limited hydrophobic binding of both aryl rings and of the quaternary C-5 methyl group. Analysis of the binding of a series of the 10 available structurally rigid dibenzoazabicyclo(x.y.z)alkanes, by using molecular modeling techniques, uncovered a highly significant correlation between affinity and a proposed ligand-active site hydrogen bonding vector (r = 0.950, p less than 0.001). These results are used to generate a pharmacophore of the MK-801 recognition site/PCP receptor, which accounts for the binding of all of the known ligands.« less

  17. Protection of Retinal Ganglion Cells by Caspase Substrate-Binding Peptide IQACRG from N-Methyl-d-Aspartate Receptor-Mediated Excitotoxicity

    PubMed Central

    Seki, Masaaki; Soussou, Walid; Manabe, Shin-ichi

    2010-01-01

    Purpose. This study investigated whether the enzymatically inactive caspase mimetic IQACRG protects rat retinal ganglion cells (RGCs) from excitotoxic insults. Minimally invasive delivery of the peptide to the retina was explored, and the mechanisms of neuroprotection were elucidated. Methods. IQACRG was linked to penetratin (P-IQACRG) to facilitate cellular uptake. RGC labeling by biotinylated-P-IQACRG delivered via intravitreal or subconjunctival injection was demonstrated by avidin-biotin chemistry. The authors used histologic and electrophysiological measures to evaluate the neuroprotective potential of P-IQACRG against RGC death induced by N-methyl-d-aspartate (NMDA) in vitro and in vivo. In addition, they monitored activity of an enzyme that is downstream of caspase-1, matrix metalloproteinase-9 (MMP-9), and protein levels of the caspase-3/7 substrate, myocyte enhancer factor 2C (MEF2C), to determine the effectiveness of IQACRG in blocking excessive caspase activity. Results. IQACRG significantly reduced NMDA-induced RGC death in culture and in vivo. Ex vivo electrophysiological recording of the retina on multielectrode arrays demonstrated functional rescue of RGCs by IQACRG. The authors also found that delivery of IQACRG to the retina inhibited NMDA-triggered MMP-9 activity and prevented cleavage of MEF2C protein that would otherwise have been engendered by caspase activation preceding RGC death. Strikingly, subconjunctival injection of P-IQACRG was very effective in preventing NMDA-induced RGC death in vivo. Conclusions. These data demonstrate that IQACRG protects RGCs from excitotoxicity in vitro and in vivo. The positive results with subconjunctival administration of P-IQACRG suggest that in the future this treatment may be useful clinically in diseases such as glaucoma and retinal ischemia. PMID:19815732

  18. Functional expression of ionotropic glutamate receptors in the rabbit retinal ganglion cells.

    PubMed

    Chen, Yin-Peng; Chiao, Chuan-Chin

    2012-01-03

    It has been known that retinal ganglion cells (RGCs) with distinct morphologies have different physiological properties. It was hypothesized that different functions of RGCs may in part result from various expressions of N-methyl-d-aspartate (NMDA), α-amino-3-hydroxyl-5-methyl-isoxazole-4-propinoic acid (AMPA), and kainic acid (KA) receptors on their dendrites. In the present study, we aimed to characterize the functional expression of AMPA and NMDA receptors of morphologically identified RGCs in the wholemount rabbit retina. The agmatine (AGB) activation assay was used to reveal functional expression of ionotropic glutamate receptors after the RGCs were targeted by injecting Neurobiotin. To examine the excitability of these glutamate receptors in an agonist specific manner, the lower concentrations of AMPA (2 μM) and NMDA (100 μM) were chosen to examine G7 (ON-OFF direction selective ganglion cells) and G11 (alpha ganglion cells) types of RGCs. We found that less than 40% of G7 type RGCs had salient AGB activation when incubated with 2 μM AMPA or 100 μM NMDA. The G11 type RGCs also showed similar activation frequencies, except that all of the OFF subtype examined had no AGB permeation under the same AMPA concentration. These results suggest that RGCs with large somata (G7 and G11 types) may express various heterogeneous functional ionotropic glutamate receptors, thus in part rendering their functional diversity. Copyright © 2011 Elsevier B.V. All rights reserved.

  19. Glutamate mediates platelet activation through the AMPA receptor

    PubMed Central

    Morrell, Craig N.; Sun, Henry; Ikeda, Masahiro; Beique, Jean-Claude; Swaim, Anne Marie; Mason, Emily; Martin, Tanika V.; Thompson, Laura E.; Gozen, Oguz; Ampagoomian, David; Sprengel, Rolf; Rothstein, Jeffrey; Faraday, Nauder; Huganir, Richard; Lowenstein, Charles J.

    2008-01-01

    Glutamate is an excitatory neurotransmitter that binds to the kainate receptor, the N-methyl-D-aspartate (NMDA) receptor, and the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor (AMPAR). Each receptor was first characterized and cloned in the central nervous system (CNS). Glutamate is also present in the periphery, and glutamate receptors have been identified in nonneuronal tissues, including bone, heart, kidney, pancreas, and platelets. Platelets play a central role in normal thrombosis and hemostasis, as well as contributing greatly to diseases such as stroke and myocardial infarction. Despite the presence of glutamate in platelet granules, the role of glutamate during hemostasis is unknown. We now show that activated platelets release glutamate, that platelets express AMPAR subunits, and that glutamate increases agonist-induced platelet activation. Furthermore, we demonstrate that glutamate binding to the AMPAR increases intracellular sodium concentration and depolarizes platelets, which are important steps in platelet activation. In contrast, platelets treated with the AMPAR antagonist CNQX or platelets derived from GluR1 knockout mice are resistant to AMPA effects. Importantly, mice lacking GluR1 have a prolonged time to thrombosis in vivo. Our data identify glutamate as a regulator of platelet activation, and suggest that the AMPA receptor is a novel antithrombotic target. PMID:18283118

  20. Threshold to N-methyl-D-aspartate-induced seizures in mice undergoing chronic nutritional magnesium deprivation is lowered in a way partly responsive to acute magnesium and antioxidant administrations.

    PubMed

    Maurois, Pierre; Pages, Nicole; Bac, Pierre; German-Fattal, Michèle; Agnani, Geneviève; Delplanque, Bernadette; Durlach, Jean; Poupaert, Jacques; Vamecq, Joseph

    2009-02-01

    Magnesium deficiency may be induced by a diet impoverished in magnesium. This nutritional deficit promotes chronic inflammatory and oxidative stresses, hyperexcitability and, in mice, susceptibility to audiogenic seizures. Potentiation by low-magnesium concentrations of the opening of N-methyl-D-aspartate (NMDA) receptor/calcium channel in in vitro and ex vivo studies, and responsiveness to magnesium of in vivo brain injury states are now well established. By contrast, little or no specific attention has been, however, paid to the in vivo NMDA receptor function/excitability in magnesium deficiency. The present work reports for the first time that, in mice undergoing chronic nutritional deprivation in magnesium (35 v. 930 parts per million for 27 d in OF1 mice), NMDA-induced seizure threshold is significantly decreased (38 % of normal values). The attenuation in the drop of NMDA seizure threshold (percentage of reversal) was 58 and 20 % upon acute intraperitoneal administrations of magnesium chloride hexahydrate (28 mg magnesium/kg) and the antioxidant ebselen (20 mg/kg), respectively. In nutritionally magnesium-deprived animals, audiogenic seizures are completely prevented by these compound doses. Taken as a whole, our data emphasise that chronic magnesium deprivation in mice is a nutritional in vivo model for a lowered NMDA receptor activation threshold. This nutritional model responds remarkably to acute magnesium supply and moderately to acute antioxidant administration.

  1. Effects of Ethanol on Phosphorylation Site Mutants of Recombinant NMDA Receptors

    PubMed Central

    Xu, Minfu; Smothers, Corigan T.; Woodward, John J.

    2010-01-01

    N-methyl-D-aspartate (NMDA) receptors are ligand-gated ion channels activated by the neurotransmitter glutamate. These channels are highly expressed by brain neurons and are critically involved in excitatory synaptic transmission. Results from previous studies show that both native and recombinant NMDA receptors are inhibited by ethanol at concentrations associated with signs of behavioral impairment and intoxication. Given the important role that NMDA receptors play in synaptic transmission and brain function, it is important to understand the factors that regulate the ethanol inhibition of these receptors. One dynamic mechanism for regulating ethanol action may be via phosphorylation of NMDA subunits by serine-threonine and tyrosine kinases. Both NR1 and NR2 subunits contain multiple sites of phosphorylation and in the NR1 subunit, most of these are contained within the C1 domain, a carboxy-terminal cassette that is subject to alternative splicing. While results from our previous studies suggest that single phosphorylation sites do not greatly affect ethanol sensitivity of NMDA receptors, it is likely that in vivo, these subunits are phosphorylated at multiple sites by different kinases. In the present study, we constructed a series of NMDA receptor mutants at serine (S) or threonine (T) residues proposed to be sites of phosphorylation by PKA and various isoforms of PKC. Ethanol (100 mM) inhibited currents from wild-type NR1/2A and NR1/2B receptors expressed in HEK293 cells by approximately 25% and 30% respectively. This inhibition was not different in single site mutants expressing alanine (A) or aspartate/glutamate (D/E) at positions T879, S896 or T900. The mutant NR1(S890D) showed greater ethanol inhibition than NR1(890A) containing receptors although this was only observed when it was combined with the NR2A subunit. Ethanol inhibition was not altered by aspartate substitution at four serines (positions 889, 890, 896, 897) or when T879D was added to the four

  2. Functional support of glutamate as a vestibular hair cell transmitter in an amniote

    NASA Technical Reports Server (NTRS)

    Cochran, S. L.; Correia, M. J.

    1995-01-01

    Although hair cells in the cochlea and in the vestibular endorgans of anamniotes are thought to release glutamate or a similar compound as their transmitter, there is little evidence in amniotes (which, unlike anamniotes, possess both type I and II hair cells) as to the nature of the hair cell transmitters in the vestibular labyrinth. We have recorded extracellularly from single semicircular canal afferents in the turtle labyrinth maintained in vitro and have bath-applied a number of transmitter agonists and antagonists to relate the effects of these substances to the actions of the endogenous transmitter substances. Both glutamate and aspartate strongly excite the afferents while GABA and carbachol have negligible or weak effects. In contrast to its lack of effect on afferent activity in some anamniotes, N-methyl-D-aspartate (NMDA) was also found to excite these afferents. Kynurenic acid reversibly reduced the resting firing rates of the afferents and the increases in firing due to the application of glutamate and aspartate. These findings provide preliminary support for the hypothesis that glutamate (or a related compound) is also a vestibular hair cell transmitter in amniotes.

  3. Mechanical stress activates NMDA receptors in the absence of agonists.

    PubMed

    Maneshi, Mohammad Mehdi; Maki, Bruce; Gnanasambandam, Radhakrishnan; Belin, Sophie; Popescu, Gabriela K; Sachs, Frederick; Hua, Susan Z

    2017-01-03

    While studying the physiological response of primary rat astrocytes to fluid shear stress in a model of traumatic brain injury (TBI), we found that shear stress induced Ca 2+ entry. The influx was inhibited by MK-801, a specific pore blocker of N-Methyl-D-aspartic acid receptor (NMDAR) channels, and this occurred in the absence of agonists. Other NMDA open channel blockers ketamine and memantine showed a similar effect. The competitive glutamate antagonists AP5 and GluN2B-selective inhibitor ifenprodil reduced NMDA-activated currents, but had no effect on the mechanically induced Ca 2+ influx. Extracellular Mg 2+ at 2 mM did not significantly affect the shear induced Ca 2+ influx, but at 10 mM it produced significant inhibition. Patch clamp experiments showed mechanical activation of NMDAR and inhibition by MK-801. The mechanical sensitivity of NMDARs may play a role in the normal physiology of fluid flow in the glymphatic system and it has obvious relevance to TBI.

  4. 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.

  5. Indistinguishable Synaptic Pharmacodynamics of the N-Methyl-d-Aspartate Receptor Channel Blockers Memantine and Ketamine

    PubMed Central

    Emnett, Christine M.; Eisenman, Lawrence N.; Taylor, Amanda M.; Izumi, Yukitoshi; Zorumski, Charles F.

    2013-01-01

    Memantine and ketamine, voltage- and activation-dependent channel blockers of N-methyl-d-aspartate (NMDA) receptors (NMDARs), have enjoyed a recent resurgence in clinical interest. Steady-state pharmacodynamic differences between these blockers have been reported, but it is unclear whether the compounds differentially affect dynamic physiologic signaling. In this study, we explored nonequilibrium conditions relevant to synaptic transmission in hippocampal networks in dissociated culture and hippocampal slices. Equimolar memantine and ketamine had indistinguishable effects on the following measures: steady-state NMDA currents, NMDAR excitatory postsynaptic current (EPSC) decay kinetics, progressive EPSC inhibition during repetitive stimulation, and extrasynaptic NMDAR inhibition. Therapeutic drug efficacy and tolerability of memantine have been attributed to fast kinetics and strong voltage dependence. However, pulse depolarization in drug presence revealed a surprisingly slow and similar time course of equilibration for the two compounds, although memantine produced a more prominent fast component (62% versus 48%) of re-equilibration. Simulations predicted that low gating efficacy underlies the slow voltage–dependent relief from block. This prediction was empirically supported by faster voltage-dependent blocker re-equilibration with several experimental manipulations of gating efficacy. Excitatory postsynaptic potential–like voltage commands produced drug differences only with large, prolonged depolarizations unlikely to be attained physiologically. In fact, we found no difference between drugs on measures of spontaneous network activity or acute effects on plasticity in hippocampal slices. Despite indistinguishable synaptic pharmacodynamics, ketamine provided significantly greater neuroprotection from damage induced by oxygen glucose deprivation, consistent with the idea that under extreme depolarizing conditions, the biophysical difference between drugs

  6. Modeling the effect of glutamate diffusion and uptake on NMDA and non-NMDA receptor saturation.

    PubMed Central

    Holmes, W R

    1995-01-01

    One- and two-dimensional models of glutamate diffusion, uptake, and binding in the synaptic cleft were developed to determine if the release of single vesicles of glutamate would saturate NMDA and non-NMDA receptors. Ranges of parameter values were used in the simulations to determine the conditions when saturation could occur. Single vesicles of glutamate did not saturate NMDA receptors unless diffusion was very slow and the number of glutamate molecules in a vesicle was large. However, the release of eight vesicles at 400 Hz caused NMDA receptor saturation for all parameter values tested. Glutamate uptake was found to reduce NMDA receptor saturation, but the effect was smaller than that of changes in the diffusion coefficient or in the number of glutamate molecules in a vesicle. Non-NMDA receptors were not saturated unless diffusion was very slow and the number of glutamate molecules in a vesicle was large. The release of eight vesicles at 400 Hz caused significant non-NMDA receptor desensitization. The results suggest that NMDA and non-NMDA receptors are not saturated by single vesicles of glutamate under usual conditions, and that tetanic input, of the type typically used to induce long-term potentiation, will increase calcium influx by increasing receptor binding as well as by reducing voltage-dependent block of NMDA receptors. Images FIGURE 1 PMID:8580317

  7. Postoperative pain impairs subsequent performance on a spatial memory task via effects on N-methyl-D-aspartate receptor in aged rats.

    PubMed

    Chi, Haidong; Kawano, Takashi; Tamura, Takahiko; Iwata, Hideki; Takahashi, Yasuhiro; Eguchi, Satoru; Yamazaki, Fumimoto; Kumagai, Naoko; Yokoyama, Masataka

    2013-12-18

    Pain may be associated with postoperative cognitive dysfunction (POCD); however, this relationship remains under investigated. Therefore, we examined the impact of postoperative pain on cognitive functions in aged animals. Rats were allocated to the following groups: control (C), 1.2 % isoflurane for 2 hours alone (I), I with laparotomy (IL), IL with analgesia using local ropivacaine (IL+R), and IL with analgesia using systemic morphine (IL+M). Pain was assessed by rat grimace scale (RGS). Spatial memory was evaluated using a radial maze from postoperative days (POD) 3 to 14. NMDA receptor (NR) 2 subunits in hippocampus were measured by ELISA. Finally, effects of memantine, a low-affinity uncompetitive N-methyl-d-aspartate (NMDA) receptor antagonist, on postoperative cognitive performance were tested. Postoperative RGS was increased in Group IL, but not in other groups. The number of memory errors in Group I were comparable to that in Group C, whereas errors in Group IL were increased. Importantly, in Group IL+R and IL+M, cognitive impairment was not found. The memory errors were positively correlated with the levels of NMDA receptor 2 subunits in hippocampus. Prophylactic treatment with memantine could prevent the development of memory deficits observed in Group IL without an analgesic effect. Postoperative pain contributes to the development of memory deficits after anesthesia and surgery via up-regulation of hippocampal NMDA receptors. Our findings suggest that postoperative pain management may be important for the prevention of POCD in elderly patients. Copyright © 2013 Elsevier Inc. All rights reserved.

  8. The effects of N-Methyl-D-Aspartate receptor blockade during the early neurodevelopmental period on emotional behaviors and cognitive functions of adolescent Wistar rats.

    PubMed

    Kocahan, Sayad; Akillioglu, Kubra; Binokay, Secil; Sencar, Leman; Polat, Sait

    2013-05-01

    The N-Methyl-D-Aspartate (NMDA) receptor is expressed abundantly in the brain and plays an important role in neuronal development, learning and memory, neurodegenerative diseases, and neurogenesis. In this study, we evaluated the effects of NMDA receptor blockade during the early neurodevelopmental period on exploratory locomotion, anxiety-like behaviors and cognitive functions of adolescent Wistar rats. NMDA receptor hypofunction was induced 7-10 days after birth using MK-801 in rats (0.25 mg/kg twice a day for 4 days via intraperitoneal injection). The open-field (OF), elevated plus maze (EPM) and passive avoidance (PA) tests were used to evaluate exploratory locomotion, anxiety-like behaviors and cognitive functions. In the OF test, MK-801 caused an increase in locomotion behavior (p < 0.01) and in the frequency of rearing (p < 0.05). In the EPM test, MK-801 treatment increased the time spent in the open arms, the number of open arm entries and the amount of head dipping (p < 0.01). MK-801 treatment caused no statistical difference compared to the control group in the PA test (p > 0.05). Chronic NMDA receptor blockade during the critical period of maturation for the glutamatergic brain system (postnatal days 7-10) produces locomotor hyperactivity and decreased anxiety levels, but has no significant main effect on cognitive function during adolescence.

  9. Glutamate as a neurotransmitter in the brain: review of physiology and pathology.

    PubMed

    Meldrum, B S

    2000-04-01

    Glutamate is the principal excitatory neurotransmitter in brain. Our knowledge of the glutamatergic synapse has advanced enormously in the last 10 years, primarily through application of molecular biological techniques to the study of glutamate receptors and transporters. There are three families of ionotropic receptors with intrinsic cation permeable channels [N-methyl-D-aspartate (NMDA), alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and kainate]. There are three groups of metabotropic, G protein-coupled glutamate receptors (mGluR) that modify neuronal and glial excitability through G protein subunits acting on membrane ion channels and second messengers such as diacylglycerol and cAMP. There are also two glial glutamate transporters and three neuronal transporters in the brain. Glutamate is the most abundant amino acid in the diet. There is no evidence for brain damage in humans resulting from dietary glutamate. A kainate analog, domoate, is sometimes ingested accidentally in blue mussels; this potent toxin causes limbic seizures, which can lead to hippocampal and related pathology and amnesia. Endogenous glutamate, by activating NMDA, AMPA or mGluR1 receptors, may contribute to the brain damage occurring acutely after status epilepticus, cerebral ischemia or traumatic brain injury. It may also contribute to chronic neurodegeneration in such disorders as amyotrophic lateral sclerosis and Huntington's chorea. In animal models of cerebral ischemia and traumatic brain injury, NMDA and AMPA receptor antagonists protect against acute brain damage and delayed behavioral deficits. Such compounds are undergoing testing in humans, but therapeutic efficacy has yet to be established. Other clinical conditions that may respond to drugs acting on glutamatergic transmission include epilepsy, amnesia, anxiety, hyperalgesia and psychosis.

  10. Ionotropic glutamate receptor antagonists and cancer therapy: time to think out of the box?

    PubMed

    Ribeiro, Mariana P C; Custódio, José B A; Santos, Armanda E

    2017-02-01

    Glutamate has a trophic function in the development of the central nervous system, regulating the proliferation and migration of neuronal progenitors. The resemblance between neuronal embryonic and tumor cells has paved the way for the investigation of the effects of glutamate on tumor cells. Indeed, tumor cells derived from neuronal tissue express ionotropic glutamate receptor (iGluRs) subunits and iGluR antagonists decrease cell proliferation. Likewise, iGluRs subunits are expressed in several peripheral cancer cells and blockade of the N-methyl-D-aspartate (NMDA) and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) ionotropic glutamate receptor subtypes decreases their proliferation and migration. Although these mechanisms are still being investigated, the inhibition of the mitogen-activated protein kinase pathway was shown to play a key role in the antiproliferative activity of iGluR antagonists. Importantly, MK-801, a NMDAR channel blocker, was effective and well tolerated in animal models of melanoma, lung, and breast cancers, suggesting that the blockade of iGluR signaling may represent a new strategy for cancer treatment. In this review, we focus on the significance of NMDA and AMPA receptor expression in tumor cells, as well as possible therapeutic strategies targeting these receptors.

  11. Pre-synaptic glycine GlyT1 transporter--NMDA receptor interaction: relevance to NMDA autoreceptor activation in the presence of Mg2+ ions.

    PubMed

    Musante, Veronica; Summa, Maria; Cunha, Rodrigo A; Raiteri, Maurizio; Pittaluga, Anna

    2011-05-01

    Rat hippocampal glutamatergic terminals possess NMDA autoreceptors whose activation by low micromolar NMDA elicits glutamate exocytosis in the presence of physiological Mg(2+) (1.2 mM), the release of glutamate being significantly reduced when compared to that in Mg(2+)-free condition. Both glutamate and glycine were required to evoke glutamate exocytosis in 1.2 mM Mg(2+), while dizocilpine, cis-4-[phosphomethyl]-piperidine-2-carboxylic acid and 7-Cl-kynurenic acid prevented it, indicating that occupation of both agonist sites is needed for receptor activation. D-serine mimicked glycine but also inhibited the NMDA/glycine-induced release of [(3H]D-aspartate, thus behaving as a partial agonist. The NMDA/glycine-induced release in 1.2 mM Mg(2+) strictly depended on glycine uptake through the glycine transporter type 1 (GlyT1), because the GlyT1 blocker N-[3-(4'-fluorophenyl)-3-(4'-phenylphenoxy)propyl])sarcosine hydrochloride, but not the GlyT2 blocker Org 25534, prevented it. Accordingly, [(3)H]glycine was taken up during superfusion, while lowering the external concentration of Na(+), the monovalent cation co-transported with glycine by GlyT1, abrogated the NMDA-induced effect. Western blot analysis of subsynaptic fractions confirms that GlyT1 and NMDA autoreceptors co-localize at the pre-synaptic level, where GluN3A subunits immunoreactivity was also recovered. It is proposed that GlyT1s coexist with NMDA autoreceptors on rat hippocampal glutamatergic terminals and that glycine taken up by GlyT1 may permit physiological activation of NMDA pre-synaptic autoreceptors. © 2011 The Authors. Journal of Neurochemistry © 2011 International Society for Neurochemistry.

  12. Prevalence of elevated serum anti-N-methyl-D-aspartate receptor antibody titers in patients presenting exclusively with psychiatric symptoms: a comparative follow-up study.

    PubMed

    Ando, Yoshihito; Shimazaki, Haruo; Shiota, Katsutoshi; Tetsuka, Syuichi; Nakao, Koichi; Shimada, Tatsuhiro; Kurata, Kazumi; Kuroda, Jinichi; Yamashita, Akihiro; Sato, Hayato; Sato, Mamoru; Eto, Shinkichi; Onishi, Yasunori; Tanaka, Keiko; Kato, Satoshi

    2016-07-08

    Increasing numbers of patients with elevated anti-N-methyl-D-aspartate (NMDA) receptor antibody titers presenting exclusively with psychiatric symptoms have been reported. The aim of the present study was to clarify the prevalence of elevated serum anti-NMDA receptor antibody titers in patients with new-onset or acute exacerbations of psychiatric symptoms. In addition, the present study aimed to investigate the association between elevated anti-NMDA receptor titers and psychiatric symptoms. The present collaborative study included 59 inpatients (23 male, 36 female) presenting with new-onset or exacerbations of schizophrenia-like symptoms at involved institutions from June 2012 to March 2014. Patient information was collected using questionnaires. Anti-NMDA receptor antibody titers were measured using NMDAR NR1 and NR2B co-transfected human embryonic kidney (HEK) 293 cells as an antigen (cell-based assay). Statistical analyses were performed for each questionnaire item. The mean age of participants was 42.0 ± 13.7 years. Six cases had elevated serum anti-NMDA antibody titers (10.2 %), four cases were first onset, and two cases with disease duration >10 years presented with third and fifth recurrences. No statistically significant difference in vital signs or major symptoms was observed between antibody-positive and antibody-negative groups. However, a trend toward an increased frequency of schizophrenia-like symptoms was observed in the antibody-positive group. Serum anti-NMDA receptor antibody titers may be associated with psychiatric conditions. However, an association with specific psychiatric symptoms was not observed in the present study. Further studies are required to validate the utility of serum anti-NMDA receptor antibody titer measurements at the time of symptom onset.

  13. Role of N-Methyl-D-Aspartate Receptors in Action-Based Predictive Coding Deficits in Schizophrenia.

    PubMed

    Kort, Naomi S; Ford, Judith M; Roach, Brian J; Gunduz-Bruce, Handan; Krystal, John H; Jaeger, Judith; Reinhart, Robert M G; Mathalon, Daniel H

    2017-03-15

    Recent theoretical models of schizophrenia posit that dysfunction of the neural mechanisms subserving predictive coding contributes to symptoms and cognitive deficits, and this dysfunction is further posited to result from N-methyl-D-aspartate glutamate receptor (NMDAR) hypofunction. Previously, by examining auditory cortical responses to self-generated speech sounds, we demonstrated that predictive coding during vocalization is disrupted in schizophrenia. To test the hypothesized contribution of NMDAR hypofunction to this disruption, we examined the effects of the NMDAR antagonist, ketamine, on predictive coding during vocalization in healthy volunteers and compared them with the effects of schizophrenia. In two separate studies, the N1 component of the event-related potential elicited by speech sounds during vocalization (talk) and passive playback (listen) were compared to assess the degree of N1 suppression during vocalization, a putative measure of auditory predictive coding. In the crossover study, 31 healthy volunteers completed two randomly ordered test days, a saline day and a ketamine day. Event-related potentials during the talk/listen task were obtained before infusion and during infusion on both days, and N1 amplitudes were compared across days. In the case-control study, N1 amplitudes from 34 schizophrenia patients and 33 healthy control volunteers were compared. N1 suppression to self-produced vocalizations was significantly and similarly diminished by ketamine (Cohen's d = 1.14) and schizophrenia (Cohen's d = .85). Disruption of NMDARs causes dysfunction in predictive coding during vocalization in a manner similar to the dysfunction observed in schizophrenia patients, consistent with the theorized contribution of NMDAR hypofunction to predictive coding deficits in schizophrenia. Copyright © 2016 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

  14. A role for N-methyl-D-aspartate receptors in norepinephrine-induced long-lasting potentiation in the dentate gyrus.

    PubMed

    Stanton, P K; Mody, I; Heinemann, U

    1989-01-01

    Mechanisms of action of norepinephrine (NE) on dentate gyrus granule cells were studied in rat hippocampal slices using extra- and intracellular recordings and measurements of stimulus and amino acid-induced changes in extracellular Ca2+ and K+ concentration. Bath application of NE (10-50 microM) induced long-lasting potentiation of perforant path evoked potentials, and markedly enhanced high-frequency stimulus-induced Ca2+ influx and K+ efflux, actions blocked by beta-receptor antagonists and mimicked by beta agonists. Enhanced Ca2+ influx was primarily postsynaptic, since presynaptic delta [Ca2+]o in the stratum moleculare synaptic field was not altered by NE. Interestingly, the potentiation of both ionic fluxes and evoked population potentials were antagonized by the N-methyl-D-aspartate (NMDA) receptor antagonist 2-amino-5-phosphonovalerate (APV). Furthermore, NE selectively enhanced the delta [Ca2+]o delta [K+]o and extracellular slow negative field potentials elicited by iontophoretically applied NMDA, but not those induced by the excitatory amino acid quisqualate. These results suggest that granule cell influx of Ca2+ through NMDA ionophores is enhanced by NE via beta-receptor activation. In intracellular recordings, NE depolarized granule cells (4.8 +/- 1.1 mV), and increased input resistance (RN) by 34 +/- 6.5%. These actions were also blocked by either the beta-antagonist propranolol or specific beta 1-blocker metoprolol. Moreover, the depolarization and RN increase persisted for long periods (93 +/- 12 min) after NE washout. In contrast, while NE, in the presence of APV, still depolarized granule cells and increased RN, APV made these actions quickly reversible upon NE washout (16 +/- 9 min). This suggested that NE induction of long-term, but not short-term, plasticity in the dentate gyrus requires NMDA receptor activation. NE may be enhancing granule cell firing by some combination of blockade on the late Ca2+-activated K+ conductance and depolarization

  15. Anti-leucine rich glioma inactivated 1 protein and anti-N-methyl-D-aspartate receptor encephalitis show distinct patterns of brain glucose metabolism in 18F-fluoro-2-deoxy-d-glucose positron emission tomography

    PubMed Central

    2014-01-01

    Background Pathogenic autoantibodies targeting the recently identified leucine rich glioma inactivated 1 protein and the subunit 1 of the N-methyl-D-aspartate receptor induce autoimmune encephalitis. A comparison of brain metabolic patterns in 18F-fluoro-2-deoxy-d-glucose positron emission tomography of anti-leucine rich glioma inactivated 1 protein and anti-N-methyl-D-aspartate receptor encephalitis patients has not been performed yet and shall be helpful in differentiating these two most common forms of autoimmune encephalitis. Methods The brain 18F-fluoro-2-deoxy-d-glucose uptake from whole-body positron emission tomography of six anti-N-methyl-D-aspartate receptor encephalitis patients and four patients with anti-leucine rich glioma inactivated 1 protein encephalitis admitted to Hannover Medical School between 2008 and 2012 was retrospectively analyzed and compared to matched controls. Results Group analysis of anti-N-methyl-D-aspartate encephalitis patients demonstrated regionally limited hypermetabolism in frontotemporal areas contrasting an extensive hypometabolism in parietal lobes, whereas the anti-leucine rich glioma inactivated 1 protein syndrome was characterized by hypermetabolism in cerebellar, basal ganglia, occipital and precentral areas and minor frontomesial hypometabolism. Conclusions This retrospective 18F-fluoro-2-deoxy-d-glucose positron emission tomography study provides novel evidence for distinct brain metabolic patterns in patients with anti-leucine rich glioma inactivated 1 protein and anti-N-methyl-D-aspartate receptor encephalitis. PMID:24950993

  16. Prostaglandin E(2) stimulates glutamate receptor-dependent astrocyte neuromodulation in cultured hippocampal cells.

    PubMed

    Sanzgiri, R P; Araque, A; Haydon, P G

    1999-11-05

    Recent Ca(2+) imaging studies in cell culture and in situ have shown that Ca(2+) elevations in astrocytes stimulate glutamate release and increase neuronal Ca(2+) levels, and that this astrocyte-neuron signaling can be stimulated by prostaglandin E(2) (PGE(2)). We investigated the electrophysiological consequences of the PGE(2)-mediated astrocyte-neuron signaling using whole-cell recordings on cultured rat hippocampal cells. Focal application of PGE(2) to astrocytes evoked a Ca(2+) elevation in the stimulated cell by mobilizing internal Ca(2+) stores, which further propagated as a Ca(2+) wave to neighboring astrocytes. Whole-cell recordings from neurons revealed that PGE(2) evoked a slow inward current in neurons adjacent to astrocytes. This neuronal response required the presence of an astrocyte Ca(2+) wave and was mediated through both N-methyl-D-aspartate (NMDA) and non-NMDA glutamate receptors. Taken together with previous studies, these data demonstrate that PGE(2)-evoked Ca(2+) elevations in astrocyte cause the release of glutamate which activates neuronal ionotropic receptors. Copyright 1999 John Wiley & Sons, Inc.

  17. Involvement of NMDA receptor in low-frequency magnetic field-induced anxiety in mice.

    PubMed

    Salunke, Balwant P; Umathe, Sudhir N; Chavan, Jagatpalsingh G

    2014-12-01

    It had been reported that exposure to extremely low-frequency magnetic field (ELFMF) induces anxiety in human and rodents. Anxiety mediates via the activation of N-methyl-d-aspartate (NMDA) receptor, whereas activation of γ-aminobutyric acid (GABA) receptor attenuates the same. Hence, the present study was carried out to understand the contribution of NMDA and/or GABA receptors modulation in ELFMF-induced anxiety for which Swiss albino mice were exposed to ELFMF (50 Hz, 10 G) by subjecting them to Helmholtz coils. The exposure was for 8 h/day for 7, 30, 60, 90 and 120 days. Anxiety level was assessed in elevated plus maze, open field test and social interaction test, on 7th, 30th, 60th, 90th and 120th exposure day, respectively. Moreover, the role of GABA and glutamate in ELFMF-induced anxiety was assessed by treating mice with muscimol [0.25 mg/kg intraperitoneally (i.p.)], bicuculline (1.0 mg/kg i.p.), NMDA (15 mg/kg i.p.) and MK-801 (0.03 mg/kg i.p.), as a GABAA and NMDA receptor agonist and antagonist, respectively. Glutamate receptor agonist exacerbated while inhibitor attenuated the ELFMF-induced anxiety. In addition, levels of GABA and glutamate were determined in regions of the brain viz, cortex, striatum, hippocampus and hypothalamus. Experiments demonstrated significant elevation of GABA and glutamate levels in the hippocampus and hypothalamus. However, GABA receptor modulators did not produce significant effect on ELFMF-induced anxiety and elevated levels of GABA at tested dose. Together, these findings suggest that ELFMF significantly induced anxiety behavior, and indicated the involvement of NMDA receptor in its effect.

  18. Alpha7 Nicotinic Acetylcholine Receptors Play a Predominant Role in the Cholinergic Potentiation of N-Methyl-D-Aspartate Evoked Firing Responses of Hippocampal CA1 Pyramidal Cells

    PubMed Central

    Bali, Zsolt K.; Nagy, Lili V.; Hernádi, István

    2017-01-01

    The aim of the present study was to identify in vivo electrophysiological correlates of the interaction between cholinergic and glutamatergic neurotransmission underlying memory. Extracellular spike recordings were performed in the hippocampal CA1 region of anesthetized rats in combination with local microiontophoretic administration of N-methyl-D-aspartate (NMDA) and acetylcholine (ACh). Both NMDA and ACh increased the firing rate of the neurons. Furthermore, the simultaneous delivery of NMDA and ACh resulted in a more pronounced excitatory effect that was superadditive over the sum of the two mono-treatment effects and that was explained by cholinergic potentiation of glutamatergic neurotransmission. Next, animals were systemically treated with scopolamine or methyllycaconitine (MLA) to assess the contribution of muscarinic ACh receptor (mAChR) or α7 nicotinic ACh receptor (nAChR) receptor-mediated mechanisms to the observed effects. Scopolamine totally inhibited ACh-evoked firing, and attenuated the firing rate increase evoked by simultaneous application of NMDA and ACh. However, the superadditive nature of the combined effect was preserved. The α7 nAChR antagonist MLA robustly decreased the firing response to simultaneous application of NMDA and ACh, suspending their superadditive effect, without modifying the tonic firing rate increasing effect of ACh. These results provide the first in vivo electrophysiological evidence that, in the hippocampal CA1 region, α7 nAChRs contribute to pyramidal cell activity mainly through potentiation of glutamatergic signaling, while the direct cholinergic modulation of tonic firing is notably mediated by mAChRs. Furthermore, the present findings also reveal cellular physiological correlates of the interplay between cholinergic and glutamatergic agents in behavioral pharmacological models of cognitive decline. PMID:28928637

  19. Direct stimulation of pituitary prolactin release by glutamate.

    PubMed

    Login, I S

    1990-01-01

    The ability of glutamate and other excitatory amino acids to stimulate prolactin secretion when administered to adult animals is hypothesized to depend on a central site of action in the brain, but there are no data to support this position. An alternative hypothesis was tested that glutamate would stimulate prolactin release when applied directly to primary cultures of dispersed adult female rat anterior pituitary cells studied in a perifusion protocol. Glutamate increased the rate of prolactin release within two minutes in a self-limited manner. Glutamate-stimulated prolactin release was augmented about 4-fold by elimination of magnesium from the perfusate and was associated with stimulation of pituitary calcium flux. Ketamine and MK-801 both reduced the basal rate of prolactin release and abolished the effects of glutamate. Pituitary cells of 10-day-old rats responded similarly to glutamate. Exposure to glutamate did not influence subsequent responses to physiological hypothalamic secretagogues, thus the likelihood of toxicity was minimized. These results suggest that the N-methyl-D-aspartate (NMDA) subclass of the glutamate receptor complex is involved. Prolactin secretion may be regulated physiologically through a functional glutamate receptor on pituitary cells.

  20. Non-conventional apoptotic response to ionising radiation mediated by N-methyl D-aspartate receptors in immature neuronal cells

    PubMed Central

    SAMARI, NADA; DE SAINT-GEORGES, LOUIS; PANI, GIUSEPPE; BAATOUT, SARAH; LEYNS, LUC; BENOTMANE, MOHAMMED ABDERRAFI

    2013-01-01

    During cortical development, N-methyl D-aspartate (NMDA) receptors are highly involved in neuronal maturation and synapse establishment. Their implication in the phenomenon of excitotoxicity has been extensively described in several neurodegenerative diseases due to the permissive entry of Ca2+ ions and massive accumulation in the intracellular compartment, which is highly toxic to cells. Ionising radiation is also a source of stress to the cells, particularly immature neurons. Their capacity to induce cell death has been described for various cell types either by directly damaging the DNA or indirectly through the generation of reactive oxygen species responsible for the activation of a battery of stress response effectors leading in certain cases, to cell death. In this study, in order to determine whether a link exists between NMDA receptors-mediated excitotoxicity and radiation-induced cell death, we evaluated radiation-induced cell death in vitro and in vivo in maturing neurons during the fetal period. Cell death induction was assessed by TUNEL, caspase-3 activity and DNA ladder assays, with or without the administration of dizocilpine (MK-801), a non-competitive NMDA receptor antagonist which blocks neuronal Ca2+ influx. To further investigate the possible involvement of Ca2+-dependent enzyme activation, known to occur at high Ca2+ concentrations, we examined the protective effect of a calpain inhibitor on cell death induced by radiation. Doses ranging from 0.2 to 0.6 Gy of X-rays elicited a clear apoptotic response that was prevented by the injection of dizocilpine (MK-801) or calpain inhibitor. These data demonstrate the involvement of NMDA receptors in radiation-induced neuronal death by the activation of downstream effectors, including calpain-related pathways. An increased apoptotic process elicited by radiation, occurring independently of the normal developmental scheme, may eliminate post-mitotic but immature neuronal cells and deeply impair the

  1. Ionotropic glutamate receptor expression in human white matter.

    PubMed

    Christensen, Pia Crone; Samadi-Bahrami, Zahra; Pavlov, Vlady; Stys, Peter K; Moore, G R Wayne

    2016-09-06

    Glutamate is the key excitatory neurotransmitter of the central nervous system (CNS). Its role in human grey matter transmission is well understood, but this is less clear in white matter (WM). Ionotropic glutamate receptors (iGluR) are found on both neuronal cell bodies and glia as well as on myelinated axons in rodents, and rodent WM tissue is capable of glutamate release. Thus, rodent WM expresses many of the components of the traditional grey matter neuron-to-neuron synapse, but to date this has not been shown for human WM. We demonstrate the presence of iGluRs in human WM by immunofluorescence employing high-resolution spectral confocal imaging. We found that the obligatory N-methyl-d-aspartic acid (NMDA) receptor subunit GluN1 and the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor subunit GluA4 co-localized with myelin, oligodendroglial cell bodies and processes. Additionally, GluA4 colocalized with axons, often in distinct clusters. These findings may explain why human WM is vulnerable to excitotoxic events following acute insults such as stroke and traumatic brain injury and in more chronic inflammatory conditions such as multiple sclerosis (MS). Further exploration of human WM glutamate signalling could pave the way for developing future therapies modulating the glutamate-mediated damage in these and other CNS disorders. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  2. Suppression of neurite outgrowth of primary cultured hippocampal neurons is involved in impairment of glutamate metabolism and NMDA receptor function caused by nanoparticulate TiO2.

    PubMed

    Hong, Fashui; Sheng, Lei; Ze, Yuguan; Hong, Jie; Zhou, Yingjun; Wang, Ling; Liu, Dong; Yu, Xiaohong; Xu, Bingqing; Zhao, Xiaoyang; Ze, Xiao

    2015-06-01

    Numerous studies have indicated that nano-titanium dioxide (TiO2) can induce neurotoxicity in vitro and in vivo, however, it is unclear whether nano-TiO2 affects neurite outgrowth of hippocampal neurons. In order to investigate the mechanism of neurotoxicity, rat primary cultured hippocampal neurons on the fourth day of culture were exposed to 5, 15, and 30 μg/mL nano-TiO2 for 24 h, and nano-TiO2 internalization, dendritic growth, glutamate metabolism, expression of N-methyl-D-aspartate (NMDA) receptor subunits (NR1, NR2A and NR2B), calcium homeostasis, sodium current (INa) and potassium current (IK) were examined. Our findings demonstrated that nano-TiO2 crossed the membrane into the cytoplasm or nucleus, and significantly suppressed dendritic growth of primary cultured hippocampal neurons in a concentration-dependent manner. Furthermore, nano-TiO2 induced a marked release of glutamate to the extracellular region, decreased glutamine synthetase activity and increased phosphate-activated glutaminase activity, elevated intracellular calcium ([Ca(2+)]i), down-regulated protein expression of NR1, NR2A and NR2B, and increased the amplitudes of the INa and IK. In addition, nano-TiO2 increased nitric oxide and nitrice synthase, attenuated the activities of Ca(2+)-ATPase and Na(+)/K(+)-ATPase, and increased the ADP/ATP ratio in the primary neurons. Taken together, these findings indicate that nano-TiO2 inhibits neurite outgrowth of hippocampal neurons by interfering with glutamate metabolism and impairing NMDA receptor function. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. A postmortem analysis of NMDA ionotropic and group 1 metabotropic glutamate receptors in the nucleus accumbens in schizophrenia.

    PubMed

    Lum, Jeremy S; Millard, Samuel J; Huang, Xu-Feng; Ooi, Lezanne; Newell, Kelly A

    2018-03-01

    The nucleus accumbens (NAcc) has been implicated in the pathology and treatment of schizophrenia. Recent postmortem evidence suggests a hyperglutamatergic state in the NAcc. With the present study we aimed to explore possible glutamatergic alterations in the NAcc of a large schizophrenia cohort. We performed immunoblots on postmortem NAcc samples from 30 individuals who had schizophrenia and 30 matched controls. We examined the protein expression of primary glutamatergic receptors, including the N -methyl-D-aspartate (NMDA) receptor (NR1, NR2A and NR2B subunits) and the group 1 metabotropic glutamate receptor (mGluR1 and mGluR5; dimeric and monomeric forms). In addition, we measured the group 1 mGluR endogenous regulators, neurochondrin and Homer1b/c, which have recently been implicated in the pathophysiology of schizophrenia. Protein levels of glutamatergic receptors and endogenous regulators were not significantly different between the controls and individuals who had schizophrenia. Furthermore, mGluR5, but not mGluR1, showed a positive association with NMDA receptor subunits, suggesting differential interactions between these receptors in this brain region. Investigation of these proteins in antipsychotic-naive individuals, in addition to the subregions of the NAcc and subcellular fractions, will strengthen future studies. The present study does not provide evidence for glutamatergic abnormalities within the NAcc of individuals with schizophrenia. Taken together with the results of previous studies, these findings suggest NMDA receptors and group 1 mGluRs are altered in a brain region-dependent manner in individuals with schizophrenia. The differential associations between mGluR1, mGluR5 and NMDA receptors observed in this study warrant further research into the interactions of these proteins and the implications for the therapeutic and adverse effect profile of glutamatergic-based novel therapeutics.

  4. A postmortem analysis of NMDA ionotropic and group 1 metabotropic glutamate receptors in the nucleus accumbens in schizophrenia.

    PubMed

    Lum, Jeremy S; Millard, Samuel J; Huang, Xu-Feng; Ooi, Lezanne; Newell, Kelly A

    2017-10-06

    The nucleus accumbens (NAcc) has been implicated in the pathology and treatment of schizophrenia. Recent postmortem evidence suggests a hyperglutamatergic state in the NAcc. With the present study we aimed to explore possible glutamatergic alterations in the NAcc of a large schizophrenia cohort. We performed immunoblots on postmortem NAcc samples from 30 individuals who had schizophrenia and 30 matched controls. We examined the protein expression of primary glutamatergic receptors, including the N -methyl-D-aspartate (NMDA) receptor (NR1, NR2A and NR2B subunits) and the group 1 metabotropic glutamate receptor (mGluR1 and mGluR5; dimeric and monomeric forms). In addition, we measured the group 1 mGluR endogenous regulators, neurochondrin and Homer1b/c, which have recently been implicated in the pathophysiology of schizophrenia. Protein levels of glutamatergic receptors and endogenous regulators were not significantly different between the controls and individuals who had schizophrenia. Furthermore, mGluR5, but not mGluR1, showed a positive association with NMDA receptor subunits, suggesting differential interactions between these receptors in this brain region. Investigation of these proteins in antipsychotic-naive individuals, in addition to the subregions of the NAcc and subcellular fractions, will strengthen future studies. The present study does not provide evidence for glutamatergic abnormalities within the NAcc of individuals with schizophrenia. Taken together with the results of previous studies, these findings suggest NMDA receptors and group 1 mGluRs are altered in a brain region-dependent manner in individuals with schizophrenia. The differential associations between mGluR1, mGluR5 and NMDA receptors observed in this study warrant further research into the interactions of these proteins and the implications for the therapeutic and adverse effect profile of glutamatergic-based novel therapeutics.

  5. Quantitative determination of free D-Asp, L-Asp and N-methyl-D-aspartate in mouse brain tissues by chiral separation and Multiple Reaction Monitoring tandem mass spectrometry.

    PubMed

    Fontanarosa, Carolina; Pane, Francesca; Sepe, Nunzio; Pinto, Gabriella; Trifuoggi, Marco; Squillace, Marta; Errico, Francesco; Usiello, Alessandro; Pucci, Piero; Amoresano, Angela

    2017-01-01

    Several studies have suggested that free d-Asp has a crucial role in N-methyl d-Asp receptor-mediated neurotransmission playing very important functions in physiological and pathological processes. This paper describes the development of an analytical procedure for the direct and simultaneous determination of free d-Asp, l-Asp and N-methyl d-Asp in specimens of different mouse brain tissues using chiral LC-MS/MS in Multiple Reaction Monitoring scan mode. After comparing three procedures and different buffers and extraction solvents, a simple preparation procedure was selected the analytes of extraction. The method was validated by analyzing l-Asp, d-Asp and N-methyl d-Asp recovery at different spiked concentrations (50, 100 and 200 pg/μl) yielding satisfactory recoveries (75-110%), and good repeatability. Limits of detection (LOD) resulted to be 0.52 pg/μl for d-Asp, 0.46 pg/μl for l-Asp and 0.54 pg/μl for NMDA, respectively. Limits of quantification (LOQ) were 1.57 pg/μl for d-Asp, 1.41 pg/μl for l-Asp and 1.64 pg/μl for NMDA, respectively. Different concentration levels were used for constructing the calibration curves which showed good linearity. The validated method was then successfully applied to the simultaneous detection of d-Asp, l-Asp and NMDA in mouse brain tissues. The concurrent, sensitive, fast, and reproducible measurement of these metabolites in brain tissues will be useful to correlate the amount of free d-Asp with relevant neurological processes, making the LC-MS/MS MRM method well suited, not only for research work but also for clinical analyses.

  6. Opposite modulation of brain stimulation reward by NMDA and AMPA receptors in the ventral tegmental area

    PubMed Central

    Ducrot, Charles; Fortier, Emmanuel; Bouchard, Claude; Rompré, Pierre-Paul

    2013-01-01

    Previous studies have shown that blockade of ventral tegmental area (VTA) glutamate N-Methyl-D-Aspartate (NMDA) receptors induces reward, stimulates forward locomotion and enhances brain stimulation reward. Glutamate induces two types of excitatory response on VTA neurons, a fast and short lasting depolarization mediated by α-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptors and a longer lasting depolarization mediated by NMDA receptors. A role for the two glutamate receptors in modulation of VTA neuronal activity is evidenced by the functional change in AMPA and NMDA synaptic responses that result from repeated exposure to reward. Since both receptors contribute to the action of glutamate on VTA neuronal activity, we studied the effects of VTA AMPA and NMDA receptor blockade on reward induced by electrical brain stimulation. Experiments were performed on rats trained to self-administer electrical pulses in the medial posterior mesencephalon. Reward thresholds were measured with the curve-shift paradigm before and for 2 h after bilateral VTA microinjections of the AMPA antagonist, NBQX (2,3,-Dioxo-6-nitro-1,2,3,4-tetrahydrobenzo(f)quinoxaline-7-sulfonamide, 0, 80, and 800 pmol/0.5 μl/side) and of a single dose (0.825 nmol/0.5 μl/side) of the NMDA antagonist, PPPA (2R,4S)-4-(3-Phosphonopropyl)-2-piperidinecarboxylic acid). NBQX produced a dose-dependent increase in reward threshold with no significant change in maximum rate of responding. Whereas PPPA injected at the same VTA sites produced a significant time dependent decrease in reward threshold and increase in maximum rate of responding. We found a negative correlation between the magnitude of the attenuation effect of NBQX and the enhancement effect of PPPA; moreover, NBQX and PPPA were most effective when injected, respectively, into the anterior and posterior VTA. These results suggest that glutamate acts on different receptor sub-types, most likely located on different VTA neurons, to

  7. Opposite modulation of brain stimulation reward by NMDA and AMPA receptors in the ventral tegmental area.

    PubMed

    Ducrot, Charles; Fortier, Emmanuel; Bouchard, Claude; Rompré, Pierre-Paul

    2013-01-01

    Previous studies have shown that blockade of ventral tegmental area (VTA) glutamate N-Methyl-D-Aspartate (NMDA) receptors induces reward, stimulates forward locomotion and enhances brain stimulation reward. Glutamate induces two types of excitatory response on VTA neurons, a fast and short lasting depolarization mediated by α-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptors and a longer lasting depolarization mediated by NMDA receptors. A role for the two glutamate receptors in modulation of VTA neuronal activity is evidenced by the functional change in AMPA and NMDA synaptic responses that result from repeated exposure to reward. Since both receptors contribute to the action of glutamate on VTA neuronal activity, we studied the effects of VTA AMPA and NMDA receptor blockade on reward induced by electrical brain stimulation. Experiments were performed on rats trained to self-administer electrical pulses in the medial posterior mesencephalon. Reward thresholds were measured with the curve-shift paradigm before and for 2 h after bilateral VTA microinjections of the AMPA antagonist, NBQX (2,3,-Dioxo-6-nitro-1,2,3,4-tetrahydrobenzo(f)quinoxaline-7-sulfonamide, 0, 80, and 800 pmol/0.5 μl/side) and of a single dose (0.825 nmol/0.5 μl/side) of the NMDA antagonist, PPPA (2R,4S)-4-(3-Phosphonopropyl)-2-piperidinecarboxylic acid). NBQX produced a dose-dependent increase in reward threshold with no significant change in maximum rate of responding. Whereas PPPA injected at the same VTA sites produced a significant time dependent decrease in reward threshold and increase in maximum rate of responding. We found a negative correlation between the magnitude of the attenuation effect of NBQX and the enhancement effect of PPPA; moreover, NBQX and PPPA were most effective when injected, respectively, into the anterior and posterior VTA. These results suggest that glutamate acts on different receptor sub-types, most likely located on different VTA neurons, to

  8. Sensory transduction of weak electromagnetic fields: role of glutamate neurotransmission mediated by NMDA receptors.

    PubMed

    Frilot, C; Carrubba, S; Marino, A A

    2014-01-31

    Subliminal electromagnetic fields (EMFs) triggered nonlinear evoked potentials in awake but not anesthetized animals, and increased glucose metabolism in the hindbrain. Field detection occurred somewhere in the head and possibly was an unrecognized function of sensory neurons in facial skin, which synapse in the trigeminal nucleus and project to the thalamus via glutamate-dependent pathways. If so, anesthetic agents that antagonize glutamate neurotransmission would be expected to degrade EMF-evoked potentials (EEPs) to a greater extent than agents having different pharmacological effects. We tested the hypothesis using ketamine which blocks N-methyl-d-aspartate (NMDA) receptors (NMDARs), and xylazine which is an α₂-adrenoreceptor agonist. Electroencephalograms (EEGs) of rats were examined using recurrence analysis to observe EEPs in the presence and absence of ketamine and/or xylazine anesthesia. Auditory evoked potentials (AEPs) served as positive controls. The frequency of observation of evoked potentials in a given condition (wake or anesthesia) was compared with that due to chance using the Fisher's exact test. EEPs were observed in awake rats but not while they were under anesthesia produced using a cocktail of xylazine and ketamine. In another experiment each rat was measured while awake and while under anesthesia produced using either xylazine or ketamine. EEPs and AEPs were detected during wake and under xylazine (P<0.05 in each of the four measurements). In contrast, neither EEPs nor AEPs were observed when anesthesia was produced partly or wholly using ketamine. The duration and latency of the EEPs was unaltered by xylazine anesthesia. The afferent signal triggered by the transduction of weak EMFs was likely mediated by NMDAR-mediated glutamate neurotransmission. Copyright © 2013 IBRO. Published by Elsevier Ltd. All rights reserved.

  9. Magnesium Lithospermate B Implicates 3'-5'-Cyclic Adenosine Monophosphate/Protein Kinase A Pathway and N-Methyl-d-Aspartate Receptors in an Experimental Traumatic Brain Injury.

    PubMed

    Chang, Chih-Zen; Wu, Shu-Chuan; Kwan, Aij-Lie; Lin, Chih-Lung

    2015-10-01

    Decreased 3'-5'-cyclic adenosine monophosphate (cAMP), protein kinase A (PKA), and increased N-methyl-d-aspartate (NMDA) related apoptosis were observed in traumatic brain injury (TBI). It is of interest to examine the effect of magnesium lithospermate B (MLB) on cAMP/PKA pathway and NMDAR in TBI. A rodent weight-drop TBI model was used. Administration of MLB was initiated 1 week before (precondition) and 24 hours later (reversal). Cortical homogenates were harvested to measure cAMP (enzyme-linked immunosorbent assay), soluble guanylyl cyclases, PKA and NMDA receptor-2β (Western blot). In addition, cAMP kinase antagonist and H-89 dihydrochloride hydrate were used to test MLB's effect on the cytoplasm cAMP/PKA pathway after TBI. Morphologically, vacuolated neuron and activated microglia were observed in the TBI groups but absent in the MLB preconditioning and healthy controls. Induced cAMP, soluble guanylyl cyclase α1, and PKA were observed in the MLB groups, when compared with the TBI group (P < 0.01) Administration of H-89 dihydrochloride hydrate reversed the effect of MLB on cortical PKA and NMDA-2β expression after TBI. This study showed that MLB exerted an antioxidant effect on the enhancement of cytoplasm cAMP and PKA. This compound also decreased NMDA-2β levels, which may correspond to its neuroprotective effects. This finding lends credence to the presumption that MLB modulates the NMDA-2β neurotoxicity through a cAMP-dependent mechanism in the pathogenesis of TBI. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Direct interaction enables cross-talk between ionotropic and group I metabotropic glutamate receptors.

    PubMed

    Perroy, Julie; Raynaud, Fabrice; Homburger, Vincent; Rousset, Marie-Claude; Telley, Ludovic; Bockaert, Joël; Fagni, Laurent

    2008-03-14

    Functional interplay between ionotropic and metabotropic receptors frequently involves complex intracellular signaling cascades. The group I metabotropic glutamate receptor mGlu5a co-clusters with the ionotropic N-methyl-d-aspartate (NMDA) receptor in hippocampal neurons. In this study, we report that a more direct cross-talk can exist between these types of receptors. Using bioluminescence resonance energy transfer in living HEK293 cells, we demonstrate that mGlu5a and NMDA receptor clustering reflects the existence of direct physical interactions. Consequently, the mGlu5a receptor decreased NMDA receptor current, and reciprocally, the NMDA receptor strongly reduced the ability of the mGlu5a receptor to release intracellular calcium. We show that deletion of the C terminus of the mGlu5a receptor abolished both its interaction with the NMDA receptor and reciprocal inhibition of the receptors. This direct functional interaction implies a higher degree of target-effector specificity, timing, and subcellular localization of signaling than could ever be predicted with complex signaling pathways.

  11. Mechanical stress activates NMDA receptors in the absence of agonists

    PubMed Central

    Maneshi, Mohammad Mehdi; Maki, Bruce; Gnanasambandam, Radhakrishnan; Belin, Sophie; Popescu, Gabriela K.; Sachs, Frederick; Hua, Susan Z.

    2017-01-01

    While studying the physiological response of primary rat astrocytes to fluid shear stress in a model of traumatic brain injury (TBI), we found that shear stress induced Ca2+ entry. The influx was inhibited by MK-801, a specific pore blocker of N-Methyl-D-aspartic acid receptor (NMDAR) channels, and this occurred in the absence of agonists. Other NMDA open channel blockers ketamine and memantine showed a similar effect. The competitive glutamate antagonists AP5 and GluN2B-selective inhibitor ifenprodil reduced NMDA-activated currents, but had no effect on the mechanically induced Ca2+ influx. Extracellular Mg2+ at 2 mM did not significantly affect the shear induced Ca2+ influx, but at 10 mM it produced significant inhibition. Patch clamp experiments showed mechanical activation of NMDAR and inhibition by MK-801. The mechanical sensitivity of NMDARs may play a role in the normal physiology of fluid flow in the glymphatic system and it has obvious relevance to TBI. PMID:28045032

  12. NMDA ANTAGONIST MK-801 SUPPRESSES BEHAVIORAL SEIZURES, AUGMENTS AFTERDISCHARGES, BUT DOES NOT BLOCK DEVELOPMENT OF PERFORANT PATH KINDLING

    EPA Science Inventory

    The role of the N-methyl-d-aspartate (NMDA) in the development and expression of kindled seizures was assessed using a crossover design. ats were stimulated once daily in the perforant path for 10 consecutive days following administration of saline or the NMDA antagonist MK-801 (...

  13. Retrieval Is Not Necessary to Trigger Reconsolidation of Object Recognition Memory in the Perirhinal Cortex

    ERIC Educational Resources Information Center

    Santoyo-Zedillo, Marianela; Rodriguez-Ortiz, Carlos J.; Chavez-Marchetta, Gianfranco; Bermudez-Rattoni, Federico; Balderas, Israela

    2014-01-01

    Memory retrieval has been considered as requisite to initiate memory reconsolidation; however, some studies indicate that blocking retrieval does not prevent memory from undergoing reconsolidation. Since N-methyl-D-aspartate (NMDA) and a-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) glutamate receptors in the perirhinal cortex have…

  14. Neuroprotection against traumatic brain injury by xenon, but not argon, is mediated by inhibition at the N-methyl-D-aspartate receptor glycine site.

    PubMed

    Harris, Katie; Armstrong, Scott P; Campos-Pires, Rita; Kiru, Louise; Franks, Nicholas P; Dickinson, Robert

    2013-11-01

    Xenon, the inert anesthetic gas, is neuroprotective in models of brain injury. The authors investigate the neuroprotective mechanisms of the inert gases such as xenon, argon, krypton, neon, and helium in an in vitro model of traumatic brain injury. The authors use an in vitro model using mouse organotypic hippocampal brain slices, subjected to a focal mechanical trauma, with injury quantified by propidium iodide fluorescence. Patch clamp electrophysiology is used to investigate the effect of the inert gases on N-methyl-D-aspartate receptors and TREK-1 channels, two molecular targets likely to play a role in neuroprotection. Xenon (50%) and, to a lesser extent, argon (50%) are neuroprotective against traumatic injury when applied after injury (xenon 43±1% protection at 72 h after injury [N=104]; argon 30±6% protection [N=44]; mean±SEM). Helium, neon, and krypton are devoid of neuroprotective effect. Xenon (50%) prevents development of secondary injury up to 48 h after trauma. Argon (50%) attenuates secondary injury, but is less effective than xenon (xenon 50±5% reduction in secondary injury at 72 h after injury [N=104]; argon 34±8% reduction [N=44]; mean±SEM). Glycine reverses the neuroprotective effect of xenon, but not argon, consistent with competitive inhibition at the N-methyl-D-aspartate receptor glycine site mediating xenon neuroprotection against traumatic brain injury. Xenon inhibits N-methyl-D-aspartate receptors and activates TREK-1 channels, whereas argon, krypton, neon, and helium have no effect on these ion channels. Xenon neuroprotection against traumatic brain injury can be reversed by increasing the glycine concentration, consistent with inhibition at the N-methyl-D-aspartate receptor glycine site playing a significant role in xenon neuroprotection. Argon and xenon do not act via the same mechanism.

  15. Bidirectional modulation of windup by NMDA receptors in the rat spinal trigeminal nucleus.

    PubMed

    Woda, Alain; Blanc, Olivier; Voisin, Daniel L; Coste, Jérôme; Molat, Jean-Louis; Luccarini, Philippe

    2004-04-01

    Activation of afferent nociceptive pathways is subject to activity-dependent plasticity, which may manifest as windup, a progressive increase in the response of dorsal horn nociceptive neurons to repeated stimuli. At the cellular level, N-methyl-d-aspartate (NMDA) receptor activation by glutamate released from nociceptive C-afferent terminals is currently thought to generate windup. Most of the wide dynamic range nociceptive neurons that display windup, however, do not receive direct C-fibre input. It is thus unknown where the NMDA mechanisms for windup operate. Here, using the Sprague-Dawley rat trigeminal system as a model, we anatomically identify a subpopulation of interneurons that relay nociceptive information from the superficial dorsal horn where C-fibres terminate, to downstream wide dynamic range nociceptive neurons. Using in vivo electrophysiological recordings, we show that at the end of this pathway, windup was reduced (24 +/- 6%, n = 7) by the NMDA receptor antagonist AP-5 (2.0 fmol) and enhanced (62 +/- 19%, n = 12) by NMDA (1 nmol). In contrast, microinjections of AP-5 (1.0 fmol) within the superficial laminae increased windup (83 +/- 44%, n = 9), whereas NMDA dose dependently decreased windup (n = 19). These results indicate that NMDA receptor function at the segmental level depends on their precise location in nociceptive neural networks. While some NMDA receptors actually amplify pain information, the new evidence for NMDA dependent inhibition of windup we show here indicates that, simultaneously, others act in the opposite direction. Working together, the two mechanisms may provide a fine tuning of gain in pain.

  16. 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. Copyright © 2015. Published by Elsevier B.V.

  17. Is the Acute NMDA Receptor Hypofunction a Valid Model of Schizophrenia?

    PubMed Central

    Adell, Albert; Jiménez-Sánchez, Laura; López-Gil, Xavier; Romón, Tamara

    2012-01-01

    Several genetic, neurodevelopmental, and pharmacological animal models of schizophrenia have been established. This short review examines the validity of one of the most used pharmacological model of the illness, ie, the acute administration of N-methyl-D-aspartate (NMDA) receptor antagonists in rodents. In some cases, data on chronic or prenatal NMDA receptor antagonist exposure have been introduced for comparison. The face validity of acute NMDA receptor blockade is granted inasmuch as hyperlocomotion and stereotypies induced by phencyclidine, ketamine, and MK-801 are regarded as a surrogate for the positive symptoms of schizophrenia. In addition, the loss of parvalbumin-containing cells (which is one of the most compelling finding in postmortem schizophrenia brain) following NMDA receptor blockade adds construct validity to this model. However, the lack of changes in glutamic acid decarboxylase (GAD67) is at variance with human studies. It is possible that changes in GAD67 are more reflective of the neurodevelopmental condition of schizophrenia. Finally, the model also has predictive validity, in that its behavioral and transmitter activation in rodents are responsive to antipsychotic treatment. Overall, although not devoid of drawbacks, the acute administration of NMDA receptor antagonists can be considered as a good model of schizophrenia bearing a satisfactory degree of validity. PMID:21965469

  18. Brain infection with Staphylococcus aureus leads to high extracellular levels of glutamate, aspartate, γ-aminobutyric acid, and zinc.

    PubMed

    Hassel, Bjørnar; Dahlberg, Daniel; Mariussen, Espen; Goverud, Ingeborg Løstegaard; Antal, Ellen-Ann; Tønjum, Tone; Maehlen, Jan

    2014-12-01

    Staphylococcal brain infections may cause mental deterioration and epileptic seizures, suggesting interference with normal neurotransmission in the brain. We injected Staphylococcus aureus into rat striatum and found an initial 76% reduction in the extracellular level of glutamate as detected by microdialysis at 2 hr after staphylococcal infection. At 8 hr after staphylococcal infection, however, the extracellular level of glutamate had increased 12-fold, and at 20 hr it had increased >30-fold. The extracellular level of aspartate and γ-aminobutyric acid (GABA) also increased greatly. Extracellular Zn(2+) , which was estimated at ∼2.6 µmol/liter in the control situation, was increased by 330% 1-2.5 hr after staphylococcal infection and by 100% at 8 and 20 hr. The increase in extracellular glutamate, aspartate, and GABA appeared to reflect the degree of tissue damage. The area of tissue damage greatly exceeded the area of staphylococcal infiltration, pointing to soluble factors being responsible for cell death. However, the N-methyl-D-aspartate receptor antagonist MK-801 ameliorated neither tissue damage nor the increase in extracellular neuroactive amino acids, suggesting the presence of neurotoxic factors other than glutamate and aspartate. In vitro staphylococci incubated with glutamine and glucose formed glutamate, so bacteria could be an additional source of infection-related glutamate. We conclude that the dramatic increase in the extracellular concentration of neuroactive amino acids and zinc could interfere with neurotransmission in the surrounding brain tissue, contributing to mental deterioration and a predisposition to epileptic seizures, which are often seen in brain abscess patients. © 2014 Wiley Periodicals, Inc.

  19. Tumor necrosis factor regulates NMDA receptor-mediated airway smooth muscle contractile function and airway responsiveness.

    PubMed

    Anaparti, Vidyanand; Pascoe, Christopher D; Jha, Aruni; Mahood, Thomas H; Ilarraza, Ramses; Unruh, Helmut; Moqbel, Redwan; Halayko, Andrew J

    2016-08-01

    We have shown that N-methyl-d-aspartate receptors (NMDA-Rs) are receptor-operated calcium entry channels in human airway smooth muscle (HASM) during contraction. Tumor necrosis factor (TNF) augments smooth muscle contractility by influencing pathways that regulate intracellular calcium flux and can alter NMDA-R expression and activity in cortical neurons and glial cells. We hypothesized that NMDA-R-mediated Ca(2+) and contractile responses of ASM can be altered by inflammatory mediators, including TNF. In cultured HASM cells, we assessed TNF (10 ng/ml, 48 h) effect on NMDA-R subunit abundance by quantitative PCR, confocal imaging, and immunoblotting. We observed dose- and time-dependent changes in NMDA-R composition: increased obligatory NR1 subunit expression and altered regulatory NR2 and inhibitory NR3 subunits. Measuring intracellular Ca(2+) flux in Fura-2-loaded HASM cultures, we observed that TNF exposure enhanced cytosolic Ca(2+) mobilization and changed the temporal pattern of Ca(2+) flux in individual myocytes induced by NMDA, an NMDA-R selective analog of glutamate. We measured airway responses to NMDA in murine thin-cut lung slices (TCLS) from allergen-naive animals and observed significant airway contraction. However, NMDA acted as a bronchodilator in TCLS from house dust mice-challenged mice and in allergen-naive TCLS subjected to TNF exposure. All contractile or bronchodilator responses were blocked by a selective NMDA-R antagonist, (2R)-amino-5-phosphonopentanoate, and bronchodilator responses were prevented by N(G)-nitro-l-arginine methyl ester (nitric oxide synthase inhibitor) or indomethacin (cyclooxygenase inhibitor). Collectively, we show that TNF augments NMDA-R-mediated Ca(2+) mobilization in HASM cells, whereas in multicellular TCLSs allergic inflammation and TNF exposure leads to NMDA-R-mediated bronchodilation. These findings reveal the unique contribution of ionotrophic NMDA-R to airway hyperreactivity. Copyright © 2016 the American

  20. Excitatory amino acid receptors and disease.

    PubMed

    Meldrum, B S

    1992-08-01

    Recent advances in the molecular biology of excitatory amino acid receptors are reviewed. Evidence that drugs blocking the excitatory action of glutamate at the N-methyl-D-aspartate (NMDA) and non-NMDA receptors may be of clinical use in epilepsy, Parkinson's disease, cerebral ischaemia and trauma, acquired immune deficiency syndrome (AIDS) encephalopathy and neuropathic pain is summarized.

  1. X-ray structure, symmetry and mechanism of an AMPA-subtype glutamate receptor

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sobolevsky, Alexander I.; Rosconi, Michael P.; Gouaux, Eric

    2010-02-02

    Ionotropic glutamate receptors mediate most excitatory neurotransmission in the central nervous system and function by opening a transmembrane ion channel upon binding of glutamate. Despite their crucial role in neurobiology, the architecture and atomic structure of an intact ionotropic glutamate receptor are unknown. Here we report the crystal structure of the {alpha}-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA)-sensitive, homotetrameric, rat GluA2 receptor at 3.6 {angstrom} resolution in complex with a competitive antagonist. The receptor harbours an overall axis of two-fold symmetry with the extracellular domains organized as pairs of local dimers and with the ion channel domain exhibiting four-fold symmetry. A symmetry mismatchmore » between the extracellular and ion channel domains is mediated by two pairs of conformationally distinct subunits, A/C and B/D. Therefore, the stereochemical manner in which the A/C subunits are coupled to the ion channel gate is different from the B/D subunits. Guided by the GluA2 structure and site-directed cysteine mutagenesis, we suggest that GluN1 and GluN2A NMDA (N-methyl-D-aspartate) receptors have a similar architecture, with subunits arranged in a 1-2-1-2 pattern. We exploit the GluA2 structure to develop mechanisms of ion channel activation, desensitization and inhibition by non-competitive antagonists and pore blockers.« less

  2. Mechanisms of action and clinical efficacy of NMDA receptor modulators in mood disorders.

    PubMed

    Ghasemi, Mehdi; Phillips, Cristy; Fahimi, Atoossa; McNerney, Margaret Windy; Salehi, Ahmad

    2017-09-01

    Although the biogenic amine models have provided meaningful links between clinical phenomena and pharmacological management of mood disorders (MDs), the onset of action of current treatments is slow and a proportion of individuals fail to adequately respond. A growing number of investigations have focused on the glutamatergic system as a viable target. Herein we review the putative role of N-methyl-d-aspartate (NMDA) signaling in the pathophysiology of MDs. Prompting this focus are several lines of evidence: 1) altered glutamate and NMDA receptor (NMDAR) expression and functioning; 2) antidepressant effects of NMDAR signaling blockers; 3) interaction between conventional therapeutic regimens and NMDAR signaling modulators; 4) biochemical evidence of interaction between monoaminergic system and NMDAR signaling; 5) interaction between neurotrophic factors and NMDAR signaling in mood regulation; 6) cross-talk between NMDAR signaling and inflammatory processes; and 7) antidepressant effects of a number of NMDA modulators in recent clinical trials. Altogether, these studies establish a warrant for the refinement of novel compounds that target glutamatergic mechanisms for the treatment of MDs. Published by Elsevier Ltd.

  3. Agmatine protects Müller cells from high-concentration glucose-induced cell damage via N-methyl-D-aspartic acid receptor inhibition.

    PubMed

    Han, Ning; Yu, Li; Song, Zhidu; Luo, Lifu; Wu, Yazhen

    2015-07-01

    Neural injury is associated with the development of diabetic retinopathy. Müller cells provide structural and metabolic support for retinal neurons. High glucose concentrations are known to induce Müller cell activity. Agmatine is an endogenous polyamine, which is enzymatically formed in the mammalian brain and has exhibited neuroprotective effects in a number of experimental models. The aims of the present study were to investigate whether agmatine protects Müller cells from glucose-induced damage and to explore the mechanisms underlying this process. Lactate dehydrogenase activity and tumor necrosis factor-α mRNA expression were significantly reduced in Müller cells exposed to a high glucose concentration, following agmatine treatment, compared with cells not treated with agmatine. In addition, agmatine treatment inhibited glucose-induced Müller cell apoptosis, which was associated with the regulation of Bax and Bcl-2 expression. Agmatine treatment suppressed glucose-induced phosphorylation of mitogen-activated protein kinase (MAPK) protein in Müller cells. The present study demonstrated that the protective effects of agmatine on Müller cells were inhibited by N-methyl-D-aspartic acid (NMDA). The results of the present study suggested that agmatine treatment protects Müller cells from high-concentration glucose-induced cell damage. The underlying mechanisms may relate to the anti-inflammatory and antiapoptotic effects of agmatine, as well as to the inhibition of the MAPK pathway, via NMDA receptor suppression. Agmatine may be of use in the development of novel therapeutic approaches for patients with diabetic retinopathy.

  4. N-Methyl-D-aspartate receptor antagonist MK-801 and radical scavengers protect cholinergic nucleus basalis neurons against beta-amyloid neurotoxicity.

    PubMed

    Harkany, T; Mulder, J; Sasvári, M; Abrahám, I; Kónya, C; Zarándi, M; Penke, B; Luiten, P G; Nyakas, C

    1999-04-01

    Previous experimental data indicate the involvement of Ca(2+)-related excitotoxic processes, possibly mediated by N-Methyl-D-Aspartate (NMDA) receptors, in beta-amyloid (beta A) neurotoxicity. On the other hand, other lines of evidence support the view that free radical generation is a critical step in the beta A-induced neurodegenerative cascade. In the present study, therefore, a neuroprotective strategy was applied to explore the contributions of each of these pathways in beta A toxicity. beta A(1-42) was injected into the magnocellular nucleus basalis of rats, while neuroprotection was achieved by either single or combined administration of the NMDA receptor antagonist MK-801 (2.5 mg/kg) and/or a vitamin E and C complex (150 mg/kg). The degree of neurodegeneration was determined by testing the animals in consecutive series of behavioral tasks, including elevated plus maze, passive avoidance learning, small open-field and open-field paradigms, followed by acetylcholinesterase (AChE), choline-acetyltransferase (ChAT), and superoxide dismutase (SOD) biochemistry. beta A injected in the nucleus basalis elicited significant anxiety in the elevated plus maze, derangement of passive avoidance learning, and altered spontaneous behaviors in both open-field tasks. A significant decrease in both AChE and ChAT accompanied by a similar decrement of MnSOD, but not of Cu/ZnSOD provided neurochemical substrates for the behavioral changes. Each of the single drug administrations protected against the neurotoxic events, whereas the combined treatment failed to ameliorate beta A toxicity.

  5. Modulation of taurine release by glutamate receptors and nitric oxide.

    PubMed

    Oja, S S; Saransaari, P

    2000-11-01

    Taurine is held to function as a modulator and osmoregulator in the central nervous system, being of particular importance in the immature brain. In view of the possible involvement of excitatory pathways in the regulation of taurine function in the brain, the interference of glutamate receptors with taurine release from different tissue preparations in vitro and from the brain in vivo is of special interest. The release of taurine from the brain is enhanced by glutamate receptor agonists. This enhancement is inhibited by the respective receptor antagonists both in vitro and in vivo. The ionotropic N-methyl-D-aspartate (NMDA) and 2-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptor agonists appear to be the most effective in enhancing taurine release, their effects being receptor-mediated. Kainate is less effective, particularly in adults. Of the glutamate receptors, the NMDA class seems to be the most susceptible to modulation by nitric oxide. Nitric oxide also modulates taurine release, enhancing the basal release in both immature and mature hippocampus, whereas the K(+)-stimulated release is generally inhibited. Metabotropic glutamate receptors also participate in the regulation of taurine release, group I metabotropic glutamate receptors potentiating the release in the developing hippocampus, while group III receptors may be involved in the adult. Under various cell-damaging conditions, including ischemia, hypoxia and hypoglycemia, taurine release is enhanced, together with an enhanced release of excitatory amino acids. The increase in extracellular taurine upon excessive stimulation of glutamate receptors and under cell-damaging conditions may serve as an important protective mechanism against excitotoxicity, being particularly effective in the immature brain.

  6. Celastrus paniculatus seed water soluble extracts protect against glutamate toxicity in neuronal cultures from rat forebrain.

    PubMed

    Godkar, Praful B; Gordon, Richard K; Ravindran, Arippa; Doctor, Bhupendra P

    2004-08-01

    Aqueous extracts of Celastrus paniculatus (CP) seed have been reported to improve learning and memory in rats. In addition, these extracts were shown to have antioxidant properties, augmented endogenous antioxidant enzymes, and decreased lipid peroxidation in rat brain. However, water soluble extracts of CP seed (CP-WSE) have not been evaluated for their neuroprotective effects. In the study reported here, we used enriched forebrain primary neuronal cell (FBNC) cultures to study the neuroprotective effects of three CP-WSE extracts (a room temperature, WF; a hot water, HF; and an acid, AF) on glutamate-induced toxicity. FBNC were pre-treated with the CP-WSE and then with glutamate to evaluate the protection afforded against excitatory amino acid-induced toxicity. The criteria for neuroprotection were based on the effects of CP-WSE on a mitochondrial function test following glutamate-induced neurotoxicity. Pre-treatment of neuronal cells with CP-WSE significantly attenuated glutamate-induced neuronal death. To understand the molecular mechanism of action of CP-WSE, we conducted electrophysiological studies using patch-clamp techniques on N-methyl-D-aspartate (NMDA)-activated whole-cell currents in FBNC. WSE significantly and reversibly inhibited whole-cell currents activated by NMDA. The results suggest that CP-WSE protected neuronal cells against glutamate-induced toxicity by modulating glutamate receptor function.

  7. Involvement of N-methyl-d-aspartate receptors in the antidepressant-like effect of 5-hydroxytryptamine 3 antagonists in mouse forced swimming test and tail suspension test.

    PubMed

    Kordjazy, Nastaran; Haj-Mirzaian, Arya; Amiri, Shayan; Ostadhadi, Sattar; Amini-Khoei, Hossein; Dehpour, Ahmad Reza

    2016-02-01

    Recent evidence indicates that 5-hydroxytryptamine 3 (5-HT3) antagonists such as ondansetron and tropisetron exert positive behavioral effects in animal models of depression. Due to the ionotropic nature of 5-HT3 and N-methyl-d-aspartate (NMDA) receptors, plus their contribution to the pathophysiology of depression, we investigated the possible role of NMDA receptors in the antidepressant-like effect of 5-HT3 receptor antagonists in male mice. In order to evaluate the animals' behavior in response to different treatments, we performed open-field test (OFT), forced swimming test (FST), and tail-suspension test (TST), which are considered as valid tasks for measuring locomotor activity and depressive-like behaviors in mice. Our data revealed that intraperitoneal (i.p.) administration of tropisetron (5, 10, and 30mg/kg) and ondansetron (0.01, and 0.1μg/kg) significantly decreased the immobility time in FST and TST. Also, co-administration of subeffective doses of tropisetron (1mg/kg, i.p.) or ondansetron (0.001μg/kg, i.p.) with subeffective doses of NMDA receptor antagonists, ketamine (1mg/kg, i.p.), MK-801 (0.05mg/kg, i.p.) and magnesium sulfate (10mg/kg, i.p.) resulted in a reduced immobility time both in FST and TST. The subeffective dose of NMDA (NMDA receptor agonist, 75mg/kg, i.p.) abolished the effects of 5-HT3 antagonists in FST and TST, further supporting the presumed interaction between 5-HT3 and NMDA receptors. These treatments did not affect the locomotor behavior of animals in OFT. Finally, the results of our study suggest that the positive effects of 5-HT3 antagonists on the coping behavior of mice in FST and TST are at least partly mediated through NMDA receptors participation. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. Essential Role of NMDA Receptor Channel ε4 Subunit (GluN2D) in the Effects of Phencyclidine, but Not Methamphetamine

    PubMed Central

    Hagino, Yoko; Kasai, Shinya; Han, Wenhua; Yamamoto, Hideko; Nabeshima, Toshitaka; Mishina, Masayoshi; Ikeda, Kazutaka

    2010-01-01

    Phencyclidine (PCP), a noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist, increases locomotor activity in rodents and causes schizophrenia-like symptoms in humans. Although activation of the dopamine (DA) pathway is hypothesized to mediate these effects of PCP, the precise mechanisms by which PCP induces its effects remain to be elucidated. The present study investigated the effect of PCP on extracellular levels of DA (DAex) in the striatum and prefrontal cortex (PFC) using in vivo microdialysis in mice lacking the NMDA receptor channel ε1 or ε4 subunit (GluRε1 [GluN2A] or GluRε4 [GluN2D]) and locomotor activity. PCP significantly increased DAex in wildtype and GluRε1 knockout mice, but not in GluRε4 knockout mice, in the striatum and PFC. Acute and repeated administration of PCP did not increase locomotor activity in GluRε4 knockout mice. The present results suggest that PCP enhances dopaminergic transmission and increases locomotor activity by acting at GluRε4. PMID:21060893

  9. Acute Mechanisms Underlying Antibody Effects in Anti–N-Methyl-D-Aspartate Receptor Encephalitis

    PubMed Central

    Moscato, Emilia H; Peng, Xiaoyu; Jain, Ankit; Parsons, Thomas D; Dalmau, Josep; Balice-Gordon, Rita J

    2014-01-01

    Objective A severe but treatable form of immune-mediated encephalitis is associated with antibodies in serum and cerebrospinal fluid (CSF) against the GluN1 subunit of the N-methyl-D-aspartate receptor (NMDAR). Prolonged exposure of hippocampal neurons to antibodies from patients with anti-NMDAR encephalitis caused a reversible decrease in the synaptic localization and function of NMDARs. However, acute effects of the antibodies, fate of the internalized receptors, type of neurons affected, and whether neurons develop compensatory homeostatic mechanisms were unknown and are the focus of this study. Methods Dissociated hippocampal neuron cultures and rodent brain sections were used for immunocytochemical, physiological, and molecular studies. Results Patient antibodies bind to NMDARs throughout the rodent brain, and decrease NMDAR cluster density in both excitatory and inhibitory hippocampal neurons. They rapidly increase the internalization rate of surface NMDAR clusters, independent of receptor activity. This internalization likely accounts for the observed decrease in NMDAR-mediated currents, as no evidence of direct blockade was detected. Once internalized, antibody-bound NMDARs traffic through both recycling endosomes and lysosomes, similar to pharmacologically induced NMDAR endocytosis. The antibodies are responsible for receptor internalization, as their depletion from CSF abrogates these effects in hippocampal neurons. We find that although anti-NMDAR antibodies do not induce compensatory changes in glutamate receptor gene expression, they cause a decrease in inhibitory synapse density onto excitatory hippocampal neurons. Interpretation Our data support an antibody-mediated mechanism of disease pathogenesis driven by immunoglobulin-induced receptor internalization. Antibody-mediated downregulation of surface NMDARs engages homeostatic synaptic plasticity mechanisms, which may inadvertently contribute to disease progression. Ann Neurol 2014;76:108–119 PMID

  10. Design, synthesis, and evaluation of polyamine-memantine hybrids as NMDA channel blockers.

    PubMed

    Kumamoto, Takuya; Nakajima, Marie; Uga, Reina; Ihayazaka, Naoko; Kashihara, Haruna; Katakawa, Kazuaki; Ishikawa, Tsutomu; Saiki, Ryotaro; Nishimura, Kazuhiro; Igarashi, Kazuei

    2018-02-01

    N-Methyl-d-aspartate (NMDA) receptors have been implicated in learning and memory, and may also play a central role in various conditions leading to neuronal degradation. NMDA receptor antagonists could therefore be of therapeutic benefit for a number of neurological disorders. We have designed hybrid compounds of polyamines and memantine, both of which function as NMDA channel blockers. The triamine derivative with a guanidine moiety showed more potent antagonistic activity than memantine. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. NMDA/glutamate mechanism of magnesium-induced anxiolytic-like behavior in mice.

    PubMed

    Poleszak, Ewa; Wlaź, Piotr; Wróbel, Andrzej; Fidecka, Sylwia; Nowak, Gabriel

    2008-01-01

    The anxiolytic-like activity of magnesium in mice during the elevated plus maze (EPM) has been demonstrated previously. In the present study, we examined the involvement of NMDA/glutamate receptor ligands on the magnesium effect on the EPM. We demonstrated that low, ineffective doses of NMDA antagonists (the competitive NMDA antagonist CGP 37849, 0.3 mg/kg; an antagonist of the glycineB sites, L-701,324, 1 mg/kg; a partial agonist of the glycineB sites, D-cycloserine, 2.5 mg/kg; and the non-competitive NMDA antagonist MK-801, 0.05 mg/kg) administered together with an ineffective dose of magnesium (10 mg/kg) evoked a significant increase in the percentage of time spent in the open arm of the maze (an index of anxiety). Moreover, magnesium-induced anxiolytic-like activity (20 mg/kg) was antagonized by D-serine (100 nmol/mouse), an agonist of glycineB site of the NMDA receptor complex. The present study demonstrates the involvement of the NMDA/glutamate pathway in the magnesium anxiolytic-like activity in the EPM in mice, and that this activity particularly involves the glycineB sites.

  12. DEVELOPMENTAL LEAD (PB) EXPOSURE REDUCES THE ABILITY OF THE NNDA ANTAGONIST MK801 TO SUPPRESS LONG-TERM POTENTIATION (LTP) IN THE RAT DENTATE GYRUS, IN VIVO

    EPA Science Inventory

    Chronic developmental lead (Pb) exposure increases the threshold and enhances decay of long-term potentiation (LTP) in the dentate gyrus of the hippocampal formation. MK-801 and other antagonists of the N-methyl-D-aspartate (NMDA) glutamate receptor subtype impair induction of LT...

  13. Oral acetate supplementation attenuates N-methyl D-aspartate receptor hypofunction-induced behavioral phenotypes accompanied by restoration of acetyl-histone homeostasis.

    PubMed

    Singh, Seema; Choudhury, Arnab; Gusain, Priya; Parvez, Suhel; Palit, Gautam; Shukla, Shubha; Ganguly, Surajit

    2016-04-01

    Aberrations in cellular acetate-utilization processes leading to global histone hypoacetylation have been implicated in the etiology of neuropsychiatric disorders like schizophrenia. Here, we investigated the role of acetate supplementation in the form of glyceryl triacetate (GTA) for the ability to restore the N-methyl D-aspartate (NMDA) receptor-induced histone hypoacetylation and to ameliorate associated behavioral phenotypes in mice. Taking cues from the studies in SH-SY5Y cells, we monitored acetylation status of specific lysine residues of histones H3 and H4 (H3K9 and H4K8) to determine the impact of oral GTA supplementation in vivo. Mice treated chronically with MK-801 (10 days; 0.15 mg/kg daily) induced hypoacetylation of H3K9 and H4K8 in the hippocampus. Daily oral supplementation of GTA (2.9 g/kg) was able to prevent this MK801-induced hypoacetylation significantly. Though MK-801-stimulated decreases in acetyl-H3K9 and acetyl-H4K8 were found to be associated with ERK1/2 activation, GTA seemed to act independent of this pathway. Simultaneously, GTA administration was able to attenuate the chronic MK-801-induced cognitive behavior phenotypes in elevated plus maze and novel object recognition tests. Not only MK-801, GTA also demonstrated protective effects against behavioral phenotypes generated by another NMDA receptor antagonist, ketamine. Acute (single injection) ketamine-mediated hyperactivity phenotype and chronic (10 days treatment) ketamine-induced phenotype of exaggerated immobility in forced swim test were ameliorated by GTA. The signature behavioral phenotypes induced by acute and chronic regimen of NMDA receptor antagonists seemed to be attenuated by GTA. This study thus provides a therapeutic paradigm of using dietary acetate supplement in psychiatric disorders.

  14. Brain MRI Characteristics of Patients with Anti-N-Methyl-D-Aspartate Receptor Encephalitis and Their Associations with 2-Year Clinical Outcome.

    PubMed

    Zhang, T; Duan, Y; Ye, J; Xu, W; Shu, N; Wang, C; Li, K; Liu, Y

    2018-05-01

    Anti- N -methyl-D-aspertate receptor encephalitis is an autoimmune-mediated disease without specific brain MRI features. Our aim was to investigate the brain MR imaging characteristics of anti- N -methyl-D-aspartate receptor encephalitis and their associations with clinical outcome at a 2-year follow-up. We enrolled 53 patients with anti- N -methyl-D-aspartate receptor encephalitis and performed 2-year follow-up. Brain MRIs were acquired for all patients at the onset phase. The brain MR imaging manifestations were classified into 4 types: type 1: normal MR imaging findings; type 2: only hippocampal lesions; type 3: lesions not involving the hippocampus; and type 4: lesions in both the hippocampus and other brain areas. The modified Rankin Scale score at 2-year follow-up was assessed, and the association between the mRS and onset brain MR imaging characteristics was evaluated. Twenty-eight (28/53, 53%) patients had normal MR imaging findings (type 1), and the others (25/53, 47%) had abnormal MRI findings: type 2: 7 patients (13%); type 3: seven patients (13%); and type 4: eleven patients (21%). Normal brain MRI findings were more common in female patients ( P = .02). Psychiatric and behavioral abnormalities were more common in adults ( P = .015), and autonomic symptoms ( P = .025) were more common in pediatric patients. The presence of hippocampal lesions ( P = .008, OR = 9.584; 95% CI, 1.803-50.931) and relapse ( P = .043, OR = 0.111; 95% CI, 0.013-0.930) was associated with poor outcome. Normal brain MRI findings were observed in half of the patients. Lesions in the hippocampus were the most common MR imaging abnormal finding. The presence of hippocampal lesions is the main MR imaging predictor for poor prognosis in patients with anti- N -methyl-D-aspartate receptor encephalitis. © 2018 by American Journal of Neuroradiology.

  15. Alpha-Synuclein Produces Early Behavioral Alterations via Striatal Cholinergic Synaptic Dysfunction by Interacting With GluN2D N-Methyl-D-Aspartate Receptor Subunit.

    PubMed

    Tozzi, Alessandro; de Iure, Antonio; Bagetta, Vincenza; Tantucci, Michela; Durante, Valentina; Quiroga-Varela, Ana; Costa, Cinzia; Di Filippo, Massimiliano; Ghiglieri, Veronica; Latagliata, Emanuele Claudio; Wegrzynowicz, Michal; Decressac, Mickael; Giampà, Carmela; Dalley, Jeffrey W; Xia, Jing; Gardoni, Fabrizio; Mellone, Manuela; El-Agnaf, Omar Mukhtar; Ardah, Mustafa Taleb; Puglisi-Allegra, Stefano; Björklund, Anders; Spillantini, Maria Grazia; Picconi, Barbara; Calabresi, Paolo

    2016-03-01

    Advanced Parkinson's disease (PD) is characterized by massive degeneration of nigral dopaminergic neurons, dramatic motor and cognitive alterations, and presence of nigral Lewy bodies, whose main constituent is α-synuclein (α-syn). However, the synaptic mechanisms underlying behavioral and motor effects induced by early selective overexpression of nigral α-syn are still a matter of debate. We performed behavioral, molecular, and immunohistochemical analyses in two transgenic models of PD, mice transgenic for truncated human α-synuclein 1-120 and rats injected with the adeno-associated viral vector carrying wild-type human α-synuclein. We also investigated striatal synaptic plasticity by electrophysiological recordings from spiny projection neurons and cholinergic interneurons. We found that overexpression of truncated or wild-type human α-syn causes partial reduction of striatal dopamine levels and selectively blocks the induction of long-term potentiation in striatal cholinergic interneurons, producing early memory and motor alterations. These effects were dependent on α-syn modulation of the GluN2D-expressing N-methyl-D-aspartate receptors in cholinergic interneurons. Acute in vitro application of human α-syn oligomers mimicked the synaptic effects observed ex vivo in PD models. We suggest that striatal cholinergic dysfunction, induced by a direct interaction between α-syn and GluN2D-expressing N-methyl-D-aspartate receptors, represents a precocious biological marker of the disease. Copyright © 2016 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

  16. The function of metabotropic glutamate receptors in thalamus and cortex.

    PubMed

    Sherman, S Murray

    2014-04-01

    Metabotropic glutamate receptors (mGluRs) are found throughout thalamus and cortex and are clearly important to circuit behavior in both structures, and so considering only participation of ionotropic glutamate receptors (e.g., [R,S]-α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid [AMPA] and N-methyl-d-aspartate receptors [NMDA] receptors) in glutamatergic processing would be an unfortunate oversimplification. These mGluRs are found both postsynaptically, on target cells of glutamatergic afferents, and presynaptically, on various synaptic terminals themselves, and when activated, they produce prolonged effects lasting at least hundreds of msec to several sec and perhaps longer. Two main types exist: activation of group I mGluRs causes postsynaptic depolarization, and group II, hyperpolarization. Both types are implicated in synaptic plasticity, both short term and long term. Their evident importance in functioning of thalamus and cortex makes it critical to develop a better understanding of how these receptors are normally activated, especially because they also seem implicated in a wide range of neurological and cognitive pathologies.

  17. The Function of Metabotropic Glutamate Receptors in Thalamus and Cortex

    PubMed Central

    Sherman, S. Murray

    2016-01-01

    Metabotropic glutamate receptors (mGluRs) are found throughout thalamus and cortex and are clearly important to circuit behavior in both structures, and so considering only participation of ionotropic glutamate receptors (e.g., [R,S]-α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid [AMPA] and N-methyl-d-aspartate receptors [NMDA] receptors) in glutamatergic processing would be an unfortunate oversimplification. These mGluRs are found both postsynaptically, on target cells of glutamatergic afferents, and presynaptically, on various synaptic terminals themselves, and when activated, they produce prolonged effects lasting at least hundreds of msec to several sec and perhaps longer. Two main types exist: activation of group I mGluRs causes postsynaptic depolarization, and group II, hyperpolarization. Both types are implicated in synaptic plasticity, both short term and long term. Their evident importance in functioning of thalamus and cortex makes it critical to develop a better understanding of how these receptors are normally activated, especially because they also seem implicated in a wide range of neurological and cognitive pathologies. PMID:23459618

  18. Central N-acetyl aspartylglutamate deficit: a possible pathogenesis of schizophrenia.

    PubMed

    Tsai, Shih-Jen

    2005-09-01

    The "glutamate hypothesis" of schizophrenia has emerged from the finding that phencyclidine (PCP) induces psychotic-like behaviors in rodents, possibly by blocking the N-methyl-D-aspartate (NMDA) subtype of glutamate receptor, thereby causing increased glutamate release. N-acetyl aspartylglutamate (NAAG), an endogenous peptide abundant in mammalian nervous systems, is localized in certain brain cells, including cortical and hippocampal pyramidal neurons. NAAG is synthesized from N-acetylaspartate (NAA) and glutamate, and NAA availability may limit the rate of NAAG synthesis. Although NAAG is known to have some neurotransmitter-like functions, NAA does not. NAAG is a highly selective agonist of the type 3 metabotropic glutamate receptor (mGluR3, a presynaptic autoreceptor) and can inhibit glutamate release. In addition, at low levels, NAAG is an NMDA receptor antagonist, and blocking of NMDA receptors may increase glutamate release. Taken together, low central NAAG levels may antagonize the effect of glutamate at NMDA receptors and decrease its agonistic effect on presynaptic mGluR3; both activities could increase glutamate release, similar to the increase demonstrated in the PCP model of schizophrenia. In this report, it is suggested that the central NAAG deficit, possibly through decreased synthesis or increased degradation of NAAG, may play a role in the pathogenesis of schizophrenia. Evidence is presented and discussed from magnetic resonance, postmortem, animal model, schizophrenia treatment, and genetic studies. The central NAAG deficit model of schizophrenia could explain the disease process, from the perspectives of both neurodevelopment and neurodegeneration, and may point to potential treatments for schizophrenia.

  19. Stereotyped initiation of retinal waves by bipolar cells via presynaptic NMDA autoreceptors

    PubMed Central

    Zhang, Rong-wei; Li, Xiao-quan; Kawakami, Koichi; Du, Jiu-lin

    2016-01-01

    Glutamatergic retinal waves, the spontaneous patterned neural activities propagating among developing retinal ganglion cells (RGCs), instruct the activity-dependent refinement of visuotopic maps. However, its initiation and underlying mechanism remain largely elusive. Here using larval zebrafish and multiple in vivo approaches, we discover that bipolar cells (BCs) are responsible for the generation of glutamatergic retinal waves. The wave originates from BC axon terminals (ATs) and propagates laterally to nearby BCs and vertically to downstream RGCs and the optic tectum. Its initiation is triggered by the activation of and consequent glutamate release from BC ATs, and is mediated by the N-methyl-D-aspartate subtype of glutamate receptors (NMDARs) expressed at these ATs. Intercellular asymmetry of NMDAR expression at BC ATs enables the preferential initiation of waves at the temporal retina, where BC ATs express more NMDARs. Thus, our findings indicate that glutamatergic retinal waves are initiated by BCs through a presynaptic NMDA autoreceptor-dependent process. PMID:27586999

  20. Involvement of N-methyl-D-aspartate receptor subunits in zinc-mediated modification of CA1 long-term potentiation in the developing hippocampus.

    PubMed

    Takeda, Atsushi; Itagaki, Kosuke; Ando, Masaki; Oku, Naoto

    2012-03-01

    Zinc is an endogenous N-methyl-D-aspartate (NMDA) receptor blocker. It is possible that zinc-mediated modification of hippocampal CA1 long-term potentiation (LTP) is linked to the expression of NMDA receptor subunits, which varies with postnatal development. In the present study, the effect of ZnCl(2) and CaEDTA, a membrane-impermeable zinc chelator, on CA1 LTP induction was examined in hippocampal slices from immature (3-week-old) and young (6-week-old) rats. Tetanus (10-100 Hz, 1 sec)-induced CA1 LTP was more greatly enhanced in 3-week-old rats. CA1 LTP was inhibited in the presence of 2-amino-5-phosphonovalerate (APV), an NMDA receptor antagonist, and CaEDTA in 3-week-old rats, as in the case of 6-week-old rats reported previously. In 3-week-old rats, on the other hand, 5 μM ZnCl(2) attenuated NMDA receptor-mediated EPSPs more than in 6-week-old rats and significantly attenuated CA1 LTP. Moreover, 5 μM ZnCl(2) significantly attenuated CA1 LTP in the presence of (2R,4S)-4-(3-phosphonopropyl)-2-piperidinecarboxylic acid (PPPA), an NR2A antagonist, in 3-week-old rats, but not that in the presence of ifenprodil, an NR2B antagonist, suggesting that zinc-mediated attenuation of CA1 LTP is associated with the preferential expression of NR2B subunit in 3-week-old rats. In 6-week-old rats, however, 5 μM ZnCl(2) significantly potentiated CA1 LTP and also CA1 LTP in the presence of PPPA. The present study demonstrates that endogenous zinc may participate in the induction of CA1 LTP. It is likely that the changes in expression of NMDA receptor subunits are involved in the zinc-mediated modification of CA1 LTP in the developing hippocampus. Copyright © 2011 Wiley Periodicals, Inc.

  1. Acute Ethanol Exposure Prevents PMA-mediated Augmentation of N-methyl-d-aspartate Receptor Function in Primary Cultured Cerebellar Granule Cells

    PubMed Central

    Reneau, Jason; Reyland, Mary E.; Popp, R. Lisa

    2011-01-01

    Many intracellular proteins and signaling cascades contribute to the ethanol sensitivity of native N-methyl-d-aspartate receptors (NMDARs). One putative protein is the serine / threonine kinase, Protein kinase C (PKC). The purpose of this study was to assess if PKC modulates the ethanol sensitivity of native NMDARs expressed in primary cultured cerebellar granule cells (CGCs). With the whole-cell patch-clamp technique, we assessed if ethanol inhibition of NMDA-induced currents (INMDA) (100 μM NMDA plus 10 μM glycine) were altered in CGCs in which the novel and classical PKC isoforms were activated by phorbol-12-myristate-13-acetate (PMA). Percent inhibition by 10, 50 or 100 mM ethanol of NMDA-induced steady-state (ISS) or peak current amplitudes (IPk) of NMDARs expressed in CGCs in which PKC was activated by a 12.5 min, 100 nM PMA exposure at 37° C did not differ from currents obtained from receptors contained in control cells. However, PMA-mediated augmentation of IPk in the absence of ethanol was abolished after brief applications of 10 or 1 mM ethanol co-applied with agonists, and this suppression of enhanced receptor function was observed for up to eight minutes post-ethanol exposure. Because we had previously shown that PMA-mediated augmentation of INMDA of NMDARs expressed in these cells is by activation of PKCα, we assessed the effect of ethanol (1, 10, 50 and 100 mM) on PKCα activity. Ethanol decreased PKCα activity by 18% for 1 mM ethanol and activity decreased with increasing ethanol concentrations with a 50% inhibition observed with 100 mM ethanol. The data suggest that ethanol disruption of PMA-mediated augmentation of INMDA may be due to a decrease in PKCα activity by ethanol. However, given the incomplete blockade of PKCα activity and the low concentration of ethanol at which this phenomenon is observed, other ethanol-sensitive signaling cascades must also be involved. PMID:21624785

  2. Memantine: targeting glutamate excitotoxicity in Alzheimer's disease and other dementias.

    PubMed

    Molinuevo, José L; Lladó, Albert; Rami, Lorena

    2005-01-01

    The management of dementia has changed since the development of new antidementia drugs. The benefits observed in Alzheimer's disease (AD) with selective cholinergic transmission treatments are mainly symptomatic, without clear evidence of neuroprotection. The hypothesis that glutamate-mediated neurotoxicity is involved in the pathogenesis of AD is finding increasingly more acceptance in the scientific community. Glutamate receptors are overactive, and N-methyl-D-aspartate (NMDA) receptor antagonists have therapeutic potential for the treatment of AD and other neurological disorders. Memantine is a noncompetitive NMDA antagonist that is considered a neuroprotective drug. Memantine's capacity has been demonstrated in preclinical studies, and it is considered a useful symptomatic treatment for AD. Memantine has been shown to benefit cognition, function, and global outcome in patients with moderate to severe AD, and it is currently approved by the US Food and Drug Administration (FDA) for the treatment of moderate to severe AD. Recently, memantine has also demonstrated efficacy in the initial stages of AD, although FDA authorization is pending. This review highlights the important pharmacological and clinical aspects of memantine, as well as some basic mechanisms mediating glutamatergic neurodegeneration.

  3. Synthesis and biological evaluation of cyclopropyl analogues of 2-amino-5-phosphonopentanoic acid

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dappen, M.S.; Pellicciari, R.; Natalini, B.

    1991-01-01

    A series of cyclopropyl analogues related to 2-amino-5-phosphonopentanoic acid (AP5) were synthesized and their biological activity was assessed as competitive antagonists for the N-methyl-D-aspartate (NMDA) receptor. In vitro receptor binding using (3H)-L-glutamate as the radioligand provided affinity data, while modulation of (3H)MK-801 binding was used as a functional assay. The analogues were also evaluated in (3H)kainate binding to assess selectivity over non-NMDA glutamate receptors. Of the compounds tested, 4,5-methano-AP5 analogue 26 was the most potent selective NMDA antagonist; however, potency was lower than that for (((+/-)-2-carboxypiperidin-4-yl)methyl)phosphonic acid (CGS 19755, 5).

  4. Agmatine protects Müller cells from high-concentration glucose-induced cell damage via N-methyl-D-aspartic acid receptor inhibition

    PubMed Central

    HAN, NING; YU, LI; SONG, ZHIDU; LUO, LIFU; WU, YAZHEN

    2015-01-01

    Neural injury is associated with the development of diabetic retinopathy. Müller cells provide structural and metabolic support for retinal neurons. High glucose concentrations are known to induce Müller cell activity. Agmatine is an endogenous polyamine, which is enzymatically formed in the mammalian brain and has exhibited neuroprotective effects in a number of experimental models. The aims of the present study were to investigate whether agmatine protects Müller cells from glucose-induced damage and to explore the mechanisms underlying this process. Lactate dehydrogenase activity and tumor necrosis factor-α mRNA expression were significantly reduced in Müller cells exposed to a high glucose concentration, following agmatine treatment, compared with cells not treated with agmatine. In addition, agmatine treatment inhibited glucose-induced Müller cell apoptosis, which was associated with the regulation of Bax and Bcl-2 expression. Agmatine treatment suppressed glucose-induced phosphorylation of mitogen-activated protein kinase (MAPK) protein in Müller cells. The present study demonstrated that the protective effects of agmatine on Müller cells were inhibited by N-methyl-D-aspartic acid (NMDA). The results of the present study suggested that agmatine treatment protects Müller cells from high-concentration glucose-induced cell damage. The underlying mechanisms may relate to the anti-inflammatory and antiapoptotic effects of agmatine, as well as to the inhibition of the MAPK pathway, via NMDA receptor suppression. Agmatine may be of use in the development of novel therapeutic approaches for patients with diabetic retinopathy. PMID:25816073

  5. TPEN, a Specific Zn2+ Chelator, Inhibits Sodium Dithionite and Glucose Deprivation (SDGD)-Induced Neuronal Death by Modulating Apoptosis, Glutamate Signaling, and Voltage-Gated K+ and Na+ Channels.

    PubMed

    Zhang, Feng; Ma, Xue-Ling; Wang, Yu-Xiang; He, Cong-Cong; Tian, Kun; Wang, Hong-Gang; An, Di; Heng, Bin; Xie, Lai-Hua; Liu, Yan-Qiang

    2017-03-01

    Hypoxia-ischemia-induced neuronal death is an important pathophysiological process that accompanies ischemic stroke and represents a major challenge in preventing ischemic stroke. To elucidate factors related to and a potential preventative mechanism of hypoxia-ischemia-induced neuronal death, primary neurons were exposed to sodium dithionite and glucose deprivation (SDGD) to mimic hypoxic-ischemic conditions. The effects of N,N,N',N'-tetrakis (2-pyridylmethyl) ethylenediamine (TPEN), a specific Zn 2+ -chelating agent, on SDGD-induced neuronal death, glutamate signaling (including the free glutamate concentration and expression of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptor (GluR2) and N-methyl-D-aspartate (NMDA) receptor subunits (NR2B), and voltage-dependent K + and Na + channel currents were also investigated. Our results demonstrated that TPEN significantly suppressed increases in cell death, apoptosis, neuronal glutamate release into the culture medium, NR2B protein expression, and I K as well as decreased GluR2 protein expression and Na + channel activity in primary cultured neurons exposed to SDGD. These results suggest that TPEN could inhibit SDGD-induced neuronal death by modulating apoptosis, glutamate signaling (via ligand-gated channels such as AMPA and NMDA receptors), and voltage-gated K + and Na + channels in neurons. Hence, Zn 2+ chelation might be a promising approach for counteracting the neuronal loss caused by transient global ischemia. Moreover, TPEN could represent a potential cell-targeted therapy.

  6. Initial evaluation of 18F-GE-179, a putative PET Tracer for activated N-methyl D-aspartate receptors.

    PubMed

    McGinnity, Colm J; Hammers, Alexander; Riaño Barros, Daniela A; Luthra, Sajinder K; Jones, Paul A; Trigg, William; Micallef, Caroline; Symms, Mark R; Brooks, David J; Koepp, Matthias J; Duncan, John S

    2014-03-01

    N-methyl D-aspartate (NMDA) ion channels play a key role in a wide range of physiologic (e.g., memory and learning tasks) and pathologic processes (e.g., excitotoxicity). To date, suitable PET markers of NMDA ion channel activity have not been available. (18)F-GE-179 is a novel radioligand that selectively binds to the open/active state of the NMDA receptor ion channel, displacing the binding of (3)H-tenocyclidine from the intrachannel binding site with an affinity of 2.4 nM. No significant binding was observed with 10 nM GE-179 at 60 other neuroreceptors, channels, or transporters. We describe the kinetic behavior of the radioligand in vivo in humans. Nine healthy participants (6 men, 3 women; median age, 37 y) each underwent a 90-min PET scan after an intravenous injection of (18)F-GE-179. Continuous arterial blood sampling over the first 15 min was followed by discrete blood sampling over the duration of the scan. Brain radioactivity (KBq/mL) was measured in summation images created from the attenuation- and motion-corrected dynamic images. Metabolite-corrected parent plasma input functions were generated. We assessed the abilities of 1-, 2-, and 3-compartment models to kinetically describe cerebral time-activity curves using 6 bilateral regions of interest. Parametric volume-of-distribution (V(T)) images were generated by voxelwise rank-shaping regularization of exponential spectral analysis (RS-ESA). A 2-brain-compartment, 4-rate-constant model best described the radioligand's kinetics in normal gray matter of subjects at rest. At 30 min after injection, 37% of plasma radioactivity represented unmetabolized (18)F-GE-179. The highest mean levels of gray matter radioactivity were seen in the putamina and peaked at 7.5 min. A significant positive correlation was observed between K1 and V(T) (Spearman ρ = 0.398; P = 0.003). Between-subject coefficients of variation of V(T) ranged between 12% and 16%. Voxelwise RS-ESA yielded similar V(T)s and coefficients of

  7. Coantagonism of Glutamate Receptors and Nicotinic Acetylcholinergic Receptors Disrupts Fear Conditioning and Latent Inhibition of Fear Conditioning

    ERIC Educational Resources Information Center

    Gould, Thomas J.; Lewis, Michael C.

    2005-01-01

    The present study investigated the hypothesis that both nicotinic acetylcholinergic receptors (nAChRs) and glutamate receptors ([alpha]-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptors (AMPARs) and N-methyl-D-aspartate glutamate receptors (NMDARs)) are involved in fear conditioning, and may modulate similar processes. The effects of the…

  8. Nedd4 is a Specific E3 Ubiquitin Ligase for the NMDA Receptor Subunit GluN2D

    PubMed Central

    Gautam, Vivek; Trinidad, Jonathan C.; Rimerman, Ronald A.; Costa, Blaise M.; Burlingame, Alma L.; Monaghan, Daniel T.

    2013-01-01

    NMDA receptors are a family of glutamate-gated ion channels that regulate various CNS functions such as synaptic plasticity and learning. However hypo-or hyper-activation of NMDA receptors is critically involved in many neurological and psychiatric conditions such as pain, stroke, epilepsy, neurodegeneration, schizophrenia, and depression. Thus, it is important to identify mechanisms (such as by targeted ubiquitination) that regulate the levels of individual subtypes of NMDA receptors. In this study, we used a series of tagged, carboxy terminal constructs of GluN2D to identify associating proteins from rat brain. Of seven different GluN2D C-terminal fragments used as bait, only the construct containing amino acids 983-1097 associated with an E3 ligase, Nedd4. A direct interaction between GluN2D and Nedd4 was confirmed both in vivo and in vitro. This association is mediated by an interaction between GluN2D's C-terminal PPXY motif and the 2nd and 3rd WW domains of Nedd4. Of the four GluN2 subunits, Nedd4 directly interacted with GluN2D and also weakly with GluN2A. Nedd4 coexpression with GluN2D enhances GluN2D ubiquitination and reduces GluN1/GluN2D NMDA receptor responses. These results identify Nedd4 as a novel binding partner for GluN2D and suggest a mechanism for the regulation of NMDA receptors that contains GluN2D subunit through ubiquitination-dependent downregulation. PMID:23639431

  9. [Autoimmune encephalitis associated to antibodies against the N-methyl-D-aspartate receptor: Report of two cases].

    PubMed

    Bustos, José; Sánchez, Yasmin; Medina, Jhon; Olivieri, Rommy; Mojica, Julián; Ortiz, Johan

    2017-04-01

    Anti-N-methyl-D-aspartate receptor encephalitis is a neurological syndrome that is more common in young women and is often associated with ovarian teratoma. It is characterized by acute general unspecific symptoms that evolve to neurological deterioration, psychosis and seizures. In its more advanced stage it is associated with abnormal movements and dysautonomia.We report two cases in women of 23 and 12 years of age. Given its low incidence, we present the clinical exercise that led to their diagnoses and the treatment options employed.

  10. Anti-N-Methyl-D-aspartate Receptor Encephalitis: A Severe, Potentially Reversible Autoimmune Encephalitis.

    PubMed

    Liu, Cai-Yun; Zhu, Jie; Zheng, Xiang-Yu; Ma, Chi; Wang, Xu

    2017-01-01

    Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is potentially lethal, but it is also a treatable autoimmune disorder characterized by prominent psychiatric and neurologic symptoms. It is often accompanied with teratoma or other neoplasm, especially in female patients. Anti-NMDAR antibodies in cerebrospinal fluid (CSF) and serum are characteristic features of the disease, thereby suggesting a pathogenic role in the disease. Here, we summarize recent studies that have clearly documented that both clinical manifestations and the antibodies may contribute to early diagnosis and multidisciplinary care. The clinical course of the disorder is reversible and the relapse could occur in some patients. Anti-NMDAR encephalitis coexisting with demyelinating disorders makes the diagnosis more complex; thus, clinicians should be aware of the overlapping diseases.

  11. Anti-N-Methyl-D-aspartate Receptor Encephalitis: A Severe, Potentially Reversible Autoimmune Encephalitis

    PubMed Central

    Liu, Cai-yun; Zheng, Xiang-Yu; Ma, Chi

    2017-01-01

    Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is potentially lethal, but it is also a treatable autoimmune disorder characterized by prominent psychiatric and neurologic symptoms. It is often accompanied with teratoma or other neoplasm, especially in female patients. Anti-NMDAR antibodies in cerebrospinal fluid (CSF) and serum are characteristic features of the disease, thereby suggesting a pathogenic role in the disease. Here, we summarize recent studies that have clearly documented that both clinical manifestations and the antibodies may contribute to early diagnosis and multidisciplinary care. The clinical course of the disorder is reversible and the relapse could occur in some patients. Anti-NMDAR encephalitis coexisting with demyelinating disorders makes the diagnosis more complex; thus, clinicians should be aware of the overlapping diseases. PMID:28698711

  12. Role of ionotropic glutamate receptors in delay and probability discounting in the rat.

    PubMed

    Yates, Justin R; Batten, Seth R; Bardo, Michael T; Beckmann, Joshua S

    2015-04-01

    Discounting of delayed and probabilistic reinforcement is linked to increased drug use and pathological gambling. Understanding the neurobiology of discounting is important for designing treatments for these disorders. Glutamate is considered to be involved in addiction-like behaviors; however, the role of ionotropic glutamate receptors (iGluRs) in discounting remains unclear. The current study examined the effects of N-methyl-D-aspartate (NMDA) and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) glutamate receptor blockade on performance in delay and probability discounting tasks. Following training in either delay or probability discounting, rats (n = 12, each task) received pretreatments of the NMDA receptor antagonists MK-801 (0, 0.01, 0.03, 0.1, or 0.3 mg/kg, s.c.) or ketamine (0, 1.0, 5.0, or 10.0 mg/kg, i.p.), as well as the AMPA receptor antagonist CNQX (0, 1.0, 3.0, or 5.6 mg/kg, i.p.). Hyperbolic discounting functions were used to estimate sensitivity to delayed/probabilistic reinforcement and sensitivity to reinforcer amount. An intermediate dose of MK-801 (0.03 mg/kg) decreased sensitivity to both delayed and probabilistic reinforcement. In contrast, ketamine did not affect the rate of discounting in either task but decreased sensitivity to reinforcer amount. CNQX did not alter sensitivity to reinforcer amount or delayed/probabilistic reinforcement. These results show that blockade of NMDA receptors, but not AMPA receptors, decreases sensitivity to delayed/probabilistic reinforcement (MK-801) and sensitivity to reinforcer amount (ketamine). The differential effects of MK-801 and ketamine demonstrate that sensitivities to delayed/probabilistic reinforcement and reinforcer amount are pharmacologically dissociable.

  13. NEUTRALIZATION OF THE ASPARTIC ACID RESIDUE D367, BUT NOT D454, INHIBITS BINDING OF NA+ TO THE GLUTAMATE-FREE FORM AND CYCLING OF THE GLUTAMATE TRANSPORTER EAAC1

    PubMed Central

    Tao, Zhen; Zhang, Zhou; Grewer, Christof

    2008-01-01

    Substrate transport by the plasma membrane glutamate transporter EAAC1 is coupled to cotransport of three sodium ions. One of these Na+ ions binds to the transporter already in the absence of glutamate. Here, we have investigated the possible involvement of two conserved aspartic acid residues in transmembrane segments 7 and 8 of EAAC1, D367 and D454, in Na+ cotransport. In order to test the effect of charge neutralization mutations in these positions on Na+ binding to the glutamate-free transporter, we recorded the Na+-induced anion leak current to determine the Km of EAAC1 for Na+. For EAAC1WT, this Km was determined as 120 mM. When the negative charge of D367 was neutralized by mutagenesis to asparagine, Na+ activated the anion leak current with a Km of about 2 M, indicating dramatically impaired Na+ binding to the mutant transporter. In contrast, the Na+ affinity of EAAC1D454N was virtually unchanged compared to the wild type transporter (Km = 90 mM). The reduced occupancy of the Na+ binding site of EAAC1D367N resulted in a dramatic reduction in glutamate affinity (Km = 3.6 mM, 140 mM [Na+]), which could be partially overcome by increasing extracellular [Na+]. In addition to impairing Na+ binding, the D367N mutation slowed glutamate transport, as shown by pre-steady-state kinetic analysis of transport currents, by strongly decreasing the rate of a reaction step associated with glutamate translocation. Our data are consistent with a model in which D367, but not D454 is involved in coordinating the bound Na+ in the glutamate-free transporter form. PMID:16478724

  14. Opiate and N-methyl-D-aspartate receptors in form-deprivation myopia.

    PubMed

    Fischer, A J; Seltner, R L; Stell, W K

    1998-01-01

    Pharmacological studies have implicated retinal opiate pathways in the visual regulation of ocular growth. However, the effects of opiate receptor subtype-specific compounds on form-deprivation myopia (FDM) are inconsistent (Seltner et al., 1997), and may be mediated by non-opiate receptors. The purpose of this study was to test whether opiate receptor-inactive (D-) enantiomers elicit the same FDM-suppressing effect as their opiate receptor-active (L-) counterparts. Since some opiates are thought to act at NMDA receptors, we also tested whether NMDA receptor agonists and antagonists influence ocular growth or FDM. We found that both L- and D- enantiomers of morphine-like compounds (dextrorphanol and levorphanol, and D- and L-naloxone) were equally effective in blocking FDM. The NMDA receptor antagonists dextromethorphan, MK801, and AP5 also suppressed FDM. A single toxic dose of NMDA, that destroys many subtypes of amacrine cells (including those that synthesize the opioid peptide enkephalin), induced myopia and ocular enlargement in ungoggled eyes, and eliminated the ability of form-deprivation to enhance ocular growth. The NR-1 subunit of the NMDA receptor was localized to a narrowly stratified, intense stratum at approximately 50% depth in the inner plexiform layer, diffusely throughout the proximal inner plexiform layer, and to many somata in the amacrine and ganglion cell layers. These observations suggest that most effects of opiate receptor ligands on FDM in the chick are mediated by non-opiate receptors, which are likely to include NMDA receptors. NMDA as an excitotoxin transiently enhances ocular growth, but thereafter disables retinal mechanisms that promote emmetropization and FDM. These observations are consistent with a prominent role for pathways utilizing NMDA receptors in FDM and ocular growth-control.

  15. Different effects of ionotropic and metabotropic glutamate receptor antagonists on attention and the attentional properties of nicotine.

    PubMed

    Quarta, Davide; Naylor, Christopher G; Morris, Hannah V; Patel, Swital; Genn, Rachel F; Stolerman, Ian P

    2007-09-01

    Distinct lines of evidence indicate that glutamate plays a primary role in modulating cognitive functions. Notably, competitive glutamate receptor antagonists acting at ionotropic N-methyl-d-aspartate (NMDA) or metabotropic glutamate 5 (mGlu5) receptors impair cognitive performance. Conversely, nicotine and other psychostimulants stimulate glutamatergic mechanisms and can act as cognitive enhancers. Hence we analysed the role of glutamate in performance of an attentional task and in nicotine-induced enhancement of attention by using the rodent five-choice serial reaction time task (5-CSRTT). Rats were trained to criterion performance and were then pre-dosed with either vehicle, the NMDA receptor antagonist (+)3-(2-carboxypiperazin-4-propyl)-1-propenyl-1-phosphonic acid (CPP, 0.3-2.0 mg/kg) or the mGlu5 antagonist 2-methyl-6-phenylethynyl-pyridine (MPEP, 1.0-9.0 mg/kg) and challenged with nicotine (0.2 mg/kg). Nicotine improved attentional performance, an effect that was weakened by doses of CPP that themselves had little impact on performance; importantly, CPP dose-dependently blunted the ability of nicotine to improve response accuracy, the major measure of signal detection in the paradigm. MPEP dose-dependently impaired signal detection under conditions with a high attentional load, an effect that was reversed by nicotine; thus, MPEP did not block nicotine-induced attentional enhancement. Co-administration of either CPP or MPEP with nicotine also produced a general slowing of performance characterised by increases in omission errors and response latencies and reduced anticipatory responding. It is concluded that activation of NMDA receptors may be an important determinant of the effects of nicotine in the 5-CSRTT. Stimulation of nicotinic receptors may also reverse attentional deficits associated with the impaired function of the glutamate network.

  16. Metabotropic Glutamate Receptors for Parkinson's Disease Therapy

    PubMed Central

    Gasparini, Fabrizio; Di Paolo, Thérèse; Gomez-Mancilla, Baltazar

    2013-01-01

    Excessive glutamatergic signalling within the basal ganglia is implicated in the progression of Parkinson's disease (PD) and inthe emergence of dyskinesia associated with long-term treatment with L-DOPA. There is considerable research focus on the discovery and development of compounds that modulate glutamatergic signalling via glutamate receptors, as treatments for PD and L-DOPA-induced dyskinesia (LID). Although initial preclinical studies with ionotropic glutamate receptor antagonists showed antiparkinsonian and antidyskinetic activity, their clinical use was limited due to psychiatric adverse effects, with the exception of amantadine, a weak N-methyl-d-aspartate (NMDA) antagonist, currently used to reduce dyskinesia in PD patients. Metabotropic receptor (mGlu receptor) modulators were considered to have a more favourable side-effect profile, and several agents have been studied in preclinical models of PD. The most promising results have been seen clinically with selective antagonists of mGlu5 receptor and preclinically with selective positive allosteric modulators of mGlu4 receptor. The growing understanding of glutamate receptor crosstalk also raises the possibility of more precise modulation of glutamatergic transmission, which may lead to the development of more effective agents for PD. PMID:23853735

  17. Taurine release from the developing and ageing hippocampus: stimulation by agonists of ionotropic glutamate receptors.

    PubMed

    Saransaari, P; Oja, S S

    1997-12-30

    The inhibitory amino acid taurine has been held to function as a modulator and osmoregulator in the brain, being of particular importance in the immature brain. The release of preloaded [3H]taurine was now studied in hippocampal slices from developing (7-day-old), adult (3-month-old) and ageing (6-24-month-old) mice focussing on the effects of agonists of ionotropic glutamate receptors. N-methyl-D-aspartate (NMDA), kainate and 2-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) potentiated taurine release concentration-dependently at each age, more so in the immature than in the adult and ageing hippocampus. The effect of kainate was blocked by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) in the developing and aged hippocampus and those of AMPA and NMDA by 6-nitro-7-sulphamoylbenzo[f]quinoxaline-2,3-dione (NBQX) and dizocilpine a(MK-801) at every age studied. This indicates the involvement of NMDA and AMPA receptors in taurine release throughout the life-span of mice, while the kainate-receptor-mediated release does not appear to function in adults. The increased hippocampal taurine release evoked by ionotropic glutamate receptors could act neuroprotectively, counteracting by several mechanisms the harmful effects of the simultaneous release of excitatory amino acids. The substantial release of taurine in the immature hippocampus might be particularly significant in view of the vulnerability of brain tissue to excitotoxicity at early age.

  18. Phosphodiesterase 2A Inhibitor TAK-915 Ameliorates Cognitive Impairments and Social Withdrawal in N-Methyl-d-Aspartate Receptor Antagonist-Induced Rat Models of Schizophrenia.

    PubMed

    Nakashima, Masato; Imada, Haruka; Shiraishi, Eri; Ito, Yuki; Suzuki, Noriko; Miyamoto, Maki; Taniguchi, Takahiko; Iwashita, Hiroki

    2018-04-01

    The pathophysiology of schizophrenia has been associated with glutamatergic dysfunction. Modulation of the glutamatergic signaling pathway, including N -methyl-d-aspartate (NMDA) receptors, can provide a new therapeutic target for schizophrenia. Phosphodiesterase 2A (PDE2A) is highly expressed in the forebrain, and is a dual substrate enzyme that hydrolyzes both cAMP and cGMP, which play pivotal roles as intracellular second messengers downstream of NMDA receptors. Here we characterize the in vivo pharmacological profile of a selective and brain-penetrant PDE2A inhibitor, ( N -{(1 S )-1-[3-fluoro-4-(trifluoromethoxy)phenyl]-2-methoxyethyl}-7-methoxy-2-oxo-2,3-dihydropyrido[2,3- b ]pyrazine-4(1 H )-carboxamide) (TAK-915) as a novel treatment of schizophrenia. Oral administration of TAK-915 at 3 and 10 mg/kg significantly increased cGMP levels in the frontal cortex, hippocampus, and striatum of rats. TAK-915 at 10 mg/kg significantly upregulated the phosphorylation of α -amino-3-hydroxy-5-methylisoxazole-4-proprionic acid receptor subunit GluR1 in the rat hippocampus. TAK-915 at 3 and 10 mg/kg significantly attenuated episodic memory deficits induced by the NMDA receptor antagonist (+)-MK-801 hydrogen maleate (MK-801) in the rat passive avoidance test. TAK-915 at 10 mg/kg significantly attenuated working memory deficits induced by MK-801 in the rat radial arm maze test. Additionally, TAK-915 at 10 mg/kg prevented subchronic phencyclidine-induced social withdrawal in social interaction in rats. In contrast, TAK-915 did not produce antipsychotic-like activity; TAK-915 had little effect on MK-801- or methamphetamine-induced hyperlocomotion in rats. These results suggest that TAK-915 has a potential to ameliorate cognitive impairments and social withdrawal in schizophrenia. Copyright © 2018 by The American Society for Pharmacology and Experimental Therapeutics.

  19. 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

  20. The N-methyl-D-aspartate-evoked cytoplasmic calcium increase in adult rat dorsal root ganglion neuronal somata was potentiated by substance P pretreatment in a protein kinase C-dependent manner.

    PubMed

    Castillo, C; Norcini, M; Baquero-Buitrago, J; Levacic, D; Medina, R; Montoya-Gacharna, J V; Blanck, T J J; Dubois, M; Recio-Pinto, E

    2011-03-17

    The involvement of substance P (SP) in neuronal sensitization through the activation of the neurokinin-1-receptor (NK1r) in postsynaptic dorsal horn neurons has been well established. In contrast, the role of SP and NK1r in primary sensory dorsal root ganglion (DRG) neurons, in particular in the soma, is not well understood. In this study, we evaluated whether SP modulated the NMDA-evoked transient increase in cytoplasmic Ca2+ ([Ca2+]cyt) in the soma of dissociated adult DRG neurons. Cultures were treated with nerve growth factor (NGF), prostaglandin E2 (PGE2) or both NGF+PGE2. Treatment with NGF+PGE2 increased the percentage of N-methyl-D-aspartate (NMDA) responsive neurons. There was no correlation between the percentage of NMDA responsive neurons and the level of expression of the NR1 and NR2B subunits of the NMDA receptor or of the NK1r. Pretreatment with SP did not alter the percentage of NMDA responsive neurons; while it potentiated the NMDA-evoked [Ca2+]cyt transient by increasing its magnitude and by prolonging the period during which small- and some medium-sized neurons remained NMDA responsive. The SP-mediated potentiation was blocked by the SP-antagonist ([D-Pro4, D-Trp7,9]-SP (4-11)) and by the protein kinase C (PKC) blocker bisindolylmaleimide I (BIM); and correlated with the phosphorylation of PKCε. The Nk1r agonist [Sar9, Met(O2)11]-SP (SarMet-SP) also potentiated the NMDA-evoked [Ca2+]cyt transient. Exposure to SP or SarMet-SP produced a rapid increase in the labeling of phosphorylated-PKCε. In none of the conditions we detected phosphorylation of the NR2B subunit at Ser-1303. Phosphorylation of the NR2B subunit at Tyr1472 was enhanced to a similar extent in cells exposed to NMDA, SP or NMDA+SP, and that enhancement was blocked by BIM. Our findings suggest that NGF and PGE2 may contribute to the injury-evoked sensitization of DRG neurons in part by enhancing their NMDA-evoked [Ca2+]cyt transient in all sized DRG neurons; and that SP may further

  1. N-methyl-D-aspartate receptor antagonist MK-801 prevents apoptosis in rats that have undergone fetal spinal cord transplantation following spinal hemisection.

    PubMed

    Zhang, Qiang; Shao, Yang; Zhao, Changsong; Cai, Juan; Sun, Sheng

    2014-12-01

    Spinal cord injury is the main cause of paraplegia, but effective therapies for it are lacking. Embryonic spinal cord transplantation is able to repair spinal cord injury, albeit with a large amount of neuronal apoptosis remaining in the spinal cord. MK-801, an N-methyl-D-aspartate (NMDA) receptor antagonist, is able to reduce cell death by decreasing the concentration of excitatory amino acids and preventing extracellular calcium ion influx. In this study, the effect of MK-801 on the apoptosis of spinal cord neurons in rats that have received a fetal spinal cord (FSC) transplant following spinal hemisection was investigated. Wistar rats were divided into three groups: Spinal cord hemisection injury with a combination of FSC transplantation and MK-801 treatment (group A); spinal cord hemisection injury with FSC transplantation (group B); and spinal cord injury with insertion of a Gelfoam pledget (group C). The rats were sacrificed 1, 3, 7 and 14 days after the surgery. Apoptosis in spinal slices from the injured spinal cord was examined by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling reaction, and the expression of B-cell lymphoma-2 (Bcl-2) was measured by immunohistochemistry. The positive cells were quantitatively analyzed using a computer image analysis system. The rate of apoptosis and the positive expression of Bcl-2 protein in the spinal cord neurons in the three groups decreased in the following order: C>B>A (P<0.05) and A>B>C (P<0.05), respectively. This indicates that treatment with the NMDA receptor antagonist MK-801 prevents apoptosis in the spinal cord neurons of rats that have undergone FSC transplantation following spinal hemisection.

  2. N-methyl-D-aspartate receptor antagonist MK-801 prevents apoptosis in rats that have undergone fetal spinal cord transplantation following spinal hemisection

    PubMed Central

    ZHANG, QIANG; SHAO, YANG; ZHAO, CHANGSONG; CAI, JUAN; SUN, SHENG

    2014-01-01

    Spinal cord injury is the main cause of paraplegia, but effective therapies for it are lacking. Embryonic spinal cord transplantation is able to repair spinal cord injury, albeit with a large amount of neuronal apoptosis remaining in the spinal cord. MK-801, an N-methyl-D-aspartate (NMDA) receptor antagonist, is able to reduce cell death by decreasing the concentration of excitatory amino acids and preventing extracellular calcium ion influx. In this study, the effect of MK-801 on the apoptosis of spinal cord neurons in rats that have received a fetal spinal cord (FSC) transplant following spinal hemisection was investigated. Wistar rats were divided into three groups: Spinal cord hemisection injury with a combination of FSC transplantation and MK-801 treatment (group A); spinal cord hemisection injury with FSC transplantation (group B); and spinal cord injury with insertion of a Gelfoam pledget (group C). The rats were sacrificed 1, 3, 7 and 14 days after the surgery. Apoptosis in spinal slices from the injured spinal cord was examined by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling reaction, and the expression of B-cell lymphoma-2 (Bcl-2) was measured by immunohistochemistry. The positive cells were quantitatively analyzed using a computer image analysis system. The rate of apoptosis and the positive expression of Bcl-2 protein in the spinal cord neurons in the three groups decreased in the following order: C>B>A (P<0.05) and A>B>C (P<0.05), respectively. This indicates that treatment with the NMDA receptor antagonist MK-801 prevents apoptosis in the spinal cord neurons of rats that have undergone FSC transplantation following spinal hemisection. PMID:25371724

  3. Premyelinated central axons express neurotoxic NMDA receptors: relevance to early developing white-matter injury

    PubMed Central

    Huria, Tahani; Beeraka, Narasimha Murthy; Al-Ghamdi, Badrah; Fern, Robert

    2015-01-01

    Ischemic-type injury to developing white matter is associated with the significant clinical condition cerebral palsy and with the cognitive deficits associated with premature birth. Premyelinated axons are the major cellular component of fetal white matter and loss of axon function underlies the disability, but the cellular mechanisms producing ischemic injury to premyelinated axons have not previously been described. Injury was found to require longer periods of modelled ischemia than at latter developmental points. Ischemia produced initial hyperexcitability in axons followed by loss of function after Na+ and Ca2+ influx. N-methyl-D-aspartate- (NMDA) type glutamate receptor (GluR) agonists potentiated axon injury while antagonists were protective. The NMDA GluR obligatory Nr1 subunit colocalized with markers of small premyelinated axons and expression was found at focal regions of axon injury. Ischemic injury of glial cells present in early developing white matter was NMDA GluR independent. Axons in human postconception week 18 to 23 white matter had a uniform prediameter expansion phenotype and postembedded immuno-gold labelling showed Nr1 subunit expression on the membrane of these axons, demonstrating a shared key neuropathologic feature with the rodent model. Premyelinated central axons therefore express high levels of functional NMDA GluRs that confer sensitivity to ischemic injury. PMID:25515212

  4. Mitochondrial dysfunction and lipid peroxidation in rat frontal cortex by chronic NMDA administration can be partially prevented by lithium treatment.

    PubMed

    Kim, Helena K; Isaacs-Trepanier, Cameron; Elmi, Nika; Rapoport, Stanley I; Andreazza, Ana C

    2016-05-01

    Chronic N-methyl-d-aspartate (NMDA) administration to rats may be a model to investigate excitotoxicity mediated by glutamatergic hyperactivity, and lithium has been reported to be neuroprotective. We hypothesized that glutamatergic hyperactivity in chronic NMDA injected rats would cause mitochondrial dysfunction and lipid peroxidation in the brain, and that chronic lithium treatment would ameliorate some of these NMDA-induced alterations. Rats treated with lithium for 6 weeks were injected i.p. 25 mg/kg NMDA on a daily basis for the last 21 days of lithium treatment. Brain was removed and frontal cortex was analyzed. Chronic NMDA decreased brain levels of mitochondrial complex I and III, and increased levels of the lipid oxidation products, 8-isoprostane and 4-hydroxynonenal, compared with non-NMDA injected rats. Lithium treatment prevented the NMDA-induced increments in 8-isoprostane and 4-hydroxynonenal. Our findings suggest that increased chronic activation of NMDA receptors can induce alterations in electron transport chain complexes I and III and in lipid peroxidation in brain. The NMDA-induced changes may contribute to glutamate-mediated excitotoxicity, which plays a role in brain diseases such as bipolar disorder. Lithium treatment prevented changes in 8-isoprostane and 4-hydroxynonenal, which may contribute to lithium's reported neuroprotective effect and efficacy in bipolar disorder. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Metabotropic glutamate receptor 5 responses dictate differentiation of neural progenitors to NMDA-responsive cells in fragile X syndrome.

    PubMed

    Achuta, Venkat Swaroop; Grym, Heli; Putkonen, Noora; Louhivuori, Verna; Kärkkäinen, Virve; Koistinaho, Jari; Roybon, Laurent; Castrén, Maija L

    2017-04-01

    Disrupted metabotropic glutamate receptor 5 (mGluR5) signaling is implicated in many neuropsychiatric disorders, including autism spectrum disorder, found in fragile X syndrome (FXS). Here we report that intracellular calcium responses to the group I mGluR agonist (S)-3,5-dihydroxyphenylglycine (DHPG) are augmented, and calcium-dependent mGluR5-mediated mechanisms alter the differentiation of neural progenitors in neurospheres derived from human induced pluripotent FXS stem cells and the brains of mouse model of FXS. Treatment with the mGluR5 antagonist 2-methyl-6-(phenylethynyl)-pyridine (MPEP) prevents an abnormal clustering of DHPG-responsive cells that are responsive to activation of ionotropic receptors in mouse FXS neurospheres. MPEP also corrects morphological defects of differentiated cells and enhanced migration of neuron-like cells in mouse FXS neurospheres. Unlike in mouse neurospheres, MPEP increases the differentiation of DHPG-responsive radial glial cells as well as the subpopulation of cells responsive to both DHPG and activation of ionotropic receptors in human neurospheres. However, MPEP normalizes the FXS-specific increase in the differentiation of cells responsive only to N-methyl-d-aspartate (NMDA) present in human neurospheres. Exposure to MPEP prevents the accumulation of intermediate basal progenitors in embryonic FXS mouse brain suggesting that rescue effects of GluR5 antagonist are progenitor type-dependent and species-specific differences of basal progenitors may modify effects of MPEP on the cortical development. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 77: 419-437, 2017. © 2016 Wiley Periodicals, Inc.

  6. Mechanistic Insights into Xenon Inhibition of NMDA Receptors from MD Simulations

    PubMed Central

    Liu, Lu Tian; Xu, Yan; Tang, Pei

    2010-01-01

    Inhibition of N-methyl-D-aspartate (NMDA) receptors has been viewed as a primary cause of xenon anesthesia, yet the mechanism is unclear. Here, we investigated interactions between xenon and the ligand-binding domain (LBD) of a NMDA receptor and examined xenon-induced structural and dynamical changes that are relevant to functional changes of the NMDA receptor. Several comparative molecular dynamics simulations were performed on two X-ray structures representing the open- and closed-cleft LBD of the NMDA receptor. We identified plausible xenon action sites in the LBD, including those nearby agonist sites, in the hinge region, and at the interface between two subunits. The xenon binding energy varies from −5.3 to −0.7 kcal/mol. Xenon's effect on the NMDA receptor is conformation-dependent and is produced through both competitive and non-competitive mechanisms. Xenon can promote cleft opening in the absence of agonists and consequently stabilizes the closed channel. Xenon can also bind at the interface of two subunits, alter the inter-subunit interaction, and lead to a reduction of the distance between GT-links. This reduction corresponds to a rearrangement of the channel toward a direction of pore size decreasing, implying a closed or desensitized channel. In addition to these non-competitive actions, xenon was found to weaken the glutamate binding, which could lead to low agonist efficacy and appear as competitive inhibition. PMID:20560662

  7. NMDA-induced potentiation of mGluR5 is mediated by activation of protein phosphatase 2B/calcineurin

    PubMed Central

    Alagarsamy, Sudar; Saugstad, Julie; Warren, Lee; Mansuy, Isabelle M.; Gereau, Robert W.; Conn, P. Jeffrey

    2010-01-01

    Previous reports have shown that activation of N-methyl-D-aspartate (NMDA) receptors potentiates responses to activation of the group I metabotropic glutamate receptor mGluR5 by reversing PKC-mediated desensitization of this receptor. NMDA-induced reversal of mGluR5 desensitization is dependent on activation of protein phosphatases. However, the specific protein phosphatase involved and the precise mechanism by which NMDA receptor activation reduces mGluR desensitization are not known. We have performed a series of molecular, biochemical, and genetic studies to show that NMDA-induced regulation of mGluR5 is dependent on activation of calcium-dependent protein phosphatase 2B/calcineurin (PP2B/CaN). Furthermore, we report that purified calcineurin directly dephosphorylates the C-terminal tail of mGluR5 at sites that are phosphorylated by PKC. Finally, immunoprecipitation and GST fusion protein pull-down experiments reveal that calcineurin interacts with mGluR5, suggesting that these proteins could be colocalized in a signaling complex. Taken together with previous studies, these data suggest that activation of NMDA receptors leads to activation of calcineurin and that calcineurin modulates mGluR5 function by directly dephosphorylating mGluR5 at PKC sites that are involved in desensitization of this receptor. 2005 Elsevier Ltd. All rights reserved. PMID:16005030

  8. Xenon reduces glutamate-, AMPA-, and kainate-induced membrane currents in cortical neurones.

    PubMed

    Dinse, A; Föhr, K J; Georgieff, M; Beyer, C; Bulling, A; Weigt, H U

    2005-04-01

    The anaesthetic, analgesic, and neuroprotective effects of xenon (Xe) are believed to be mediated by a block of the NMDA (N-methyl-D-aspartate) receptor channel. Interestingly, the clinical profile of the noble gas differs markedly from that of specific NMDA receptor antagonists. The aim of this study was, therefore, to investigate whether Xe might be less specific, also inhibiting the two other subtypes of glutamate receptor channels, such as the alpha-amino-3-hydroxy-5-methyl-4-isoxazolole propionate (AMPA) and kainate receptors. The study was performed on voltage-clamped cortical neurones from embryonic mice and SH-SY5Y cells expressing GluR6 kainate receptors. Drugs were applied by a multi-barreled fast perfusion system. Xe, dissolved at approximately 3.45 mM in aqueous solution, diminished the peak and even more the plateau of AMPA and glutamate induced currents. At the control EC(50) value for AMPA (29 microM) these reductions were by about 40 and 56% and at 3 mM glutamate the reductions were by 45 and 66%, respectively. Currents activated at the control EC(50) value for kainate (57 microM) were inhibited by 42%. Likewise, Xe showed an inhibitory effect on kainate-induced membrane currents of SH-SY5Y cells transfected with the GluR6 subunit of the kainate receptor. Xe reduced kainate-induced currents by between 35 and 60%, depending on the kainate concentration. Xe blocks not only NMDA receptors, but also AMPA and kainate receptors in cortical neurones as well as GluR6-type receptors expressed in SH-SY5Y cells. Thus, Xe seems to be rather non-specific as a channel blocker and this may contribute to the analgesic and anaesthetic potency of Xe.

  9. The role of GluN2B-containing NMDA receptors in short- and long-term fear recall.

    PubMed

    Mikics, Eva; Toth, Mate; Biro, Laszlo; Bruzsik, Biborka; Nagy, Boglarka; Haller, Jozsef

    2017-08-01

    N-methyl-d-aspartate (NMDA) receptors are crucial synaptic elements in long-term memory formation, including the associative learning of fearful events. Although NMDA blockers were consistently shown to inhibit fear memory acquisition and recall, the clinical use of general NMDA blockers is hampered by their side effects. Recent studies revealed significant heterogeneity in the distribution and neurophysiological characteristics of NMDA receptors with different GluN2 (NR2) subunit composition, which may have differential role in fear learning and recall. To investigate the specific role of NMDA receptor subpopulations with different GluN2 subunit compositions in the formation of lasting traumatic memories, we contrasted the effects of general NMDA receptor blockade with GluN2A-, GluN2B-, and GluN2C/D subunit selective antagonists (MK-801, PEAQX, Ro25-6981, PPDA, respectively). To investigate acute and lasting consequences, behavioral responses were investigated 1 and 28days after fear conditioning. We found that MK-801 (0.05 and 0.1mg/kg) decreased fear recall at both time points. GluN2B receptor subunit blockade produced highly similar effects, albeit efficacy was somewhat smaller 28days after fear conditioning. Unlike MK-801, Ro25-6981 (3 and 10mg/kg) did not affect locomotor activity in the open-field. In contrast, GluN2A and GluN2C/D blockers (6 and 20mg/kg PEAQX; 3 and 10mg/kg PPDA, respectively) had no effect on conditioned fear recall at any time point and dose. This sharp contrast between GluN2B- and other subunit-containing NMDA receptor function indicates that GluN2B receptor subunits are intimately involved in fear memory formation, and may provide a novel pharmacological target in post-traumatic stress disorder or other fear-related disorders. Copyright © 2017 Elsevier Inc. All rights reserved.

  10. Intrinsic motions in the N-terminal domain of an ionotropic glutamate receptor detected by fluorescence correlation spectroscopy.

    PubMed

    Jensen, Mette H; Sukumaran, Madhav; Johnson, Christopher M; Greger, Ingo H; Neuweiler, Hannes

    2011-11-18

    Ionotropic glutamate receptors (iGluRs) mediate excitatory neurotransmission in the central nervous system and play key roles in brain development and disease. iGluRs have two distinct extracellular domains, but the functional role of the distal N-terminal domain (NTD) is poorly understood. Crystal structures of the NTD from some non-N-methyl-d-aspartate (NMDA) iGluRs are consistent with a rigid body that facilitates receptor assembly but suggest an additional dynamic role that could modulate signaling. Here, we moved beyond spatial and temporal limitations of conventional protein single-molecule spectroscopy by employing correlation analysis of extrinsic oxazine fluorescence fluctuations. We observed nanosecond (ns)-to-microsecond (μs) motions of loop segments and helices within a region of an AMPA-type iGluR NTD, which has been identified previously to be structurally variable. Our data reveal that the AMPA receptor NTD undergoes rapid conformational fluctuations, suggesting an inherent allosteric capacity for this domain in addition to its established assembly function. Copyright © 2011 Elsevier Ltd. All rights reserved.

  11. Cholinergic basal forebrain structures are not essential for mediation of the arousing action of glutamate.

    PubMed

    Lelkes, Zoltán; Abdurakhmanova, Shamsiiat; Porkka-Heiskanen, Tarja

    2017-09-18

    The cholinergic basal forebrain contributes to cortical activation and receives rich innervations from the ascending activating system. It is involved in the mediation of the arousing actions of noradrenaline and histamine. Glutamatergic stimulation in the basal forebrain results in cortical acetylcholine release and suppression of sleep. However, it is not known to what extent the cholinergic versus non-cholinergic basal forebrain projection neurones contribute to the arousing action of glutamate. To clarify this question, we administered N-methyl-D-aspartate (NMDA), a glutamate agonist, into the basal forebrain in intact rats and after destruction of the cholinergic cells in the basal forebrain with 192 immunoglobulin (Ig)G-saporin. In eight Han-Wistar rats with implanted electroencephalogram/electromyogram (EEG/EMG) electrodes and guide cannulas for microdialysis probes, 0.23 μg 192 IgG-saporin was administered into the basal forebrain, while the eight control animals received artificial cerebrospinal fluid. Two weeks later, a microdialysis probe targeted into the basal forebrain was perfused with cerebrospinal fluid on the baseline day and for 3 h with 0.3 mmNMDA on the subsequent day. Sleep-wake activity was recorded for 24 h on both days. NMDA exhibited a robust arousing effect in both the intact and the lesioned rats. Wakefulness was increased and both non-REM and REM sleep were decreased significantly during the 3-h NMDA perfusion. Destruction of the basal forebrain cholinergic neurones did not abolish the wake-enhancing action of NMDA. Thus, the cholinergic basal forebrain structures are not essential for the mediation of the arousing action of glutamate. © 2017 European Sleep Research Society.

  12. Involvement of NMDA glutamate receptors in the acquisition and reinstatement of the conditioned place preference induced by MDMA.

    PubMed

    García-Pardo, Maria P; Escobar-Valero, Carla; Rodríguez-Arias, Marta; Miñarro, Jose; Aguilar, Maria A

    2015-08-01

    Some 3,4-methylenedioxymethamphetamine (MDMA) users become dependent as a result of chronic consumption. A greater understanding of the neurobiological basis of the rewarding effects of MDMA could contribute to developing effective pharmacotherapies for MDMA-related problems. The present study evaluated the role of N-methyl-D-aspartate (NMDA) glutamate receptors (NMDARs) in the acquisition and reinstatement of conditioned place preference (CPP) induced by MDMA. Adolescent male mice were conditioned with 1 or 10 mg/kg MDMA and pretreated with 5 or 10 mg/kg of the NMDAR antagonist memantine during acquisition of conditioning (experiment 1), or before a reinstatement test (experiment 2). In addition, the effects of memantine on acquisition of chocolate-induced CPP and the effects of memantine and MDMA on a passive avoidance task were evaluated. Memantine did not exert any motivational effects, but blocked the acquisition of MDMA-induced CPP. Moreover, following acquisition and extinction of MDMA-induced CPP, memantine did not induce reinstatement but blocked reinstatement of the CPP induced by priming with MDMA. Memantine did not block the CPP induced by chocolate, and it partially reversed the impairing effects of MDMA on memory. Our results demonstrate that NMDARs are involved in acquisition of the conditioned rewarding effects of MDMA and in priming-induced reinstatement of CPP following extinction. Moreover, they suggest the validity of memantine for the treatment of MDMA abuse.

  13. Voltage-dependent calcium channel involvement in NMDA-induced activation of NOS.

    PubMed

    Alagarsamy, S; Johnson, K M

    1995-11-13

    We have previously shown that N-methyl-D-aspartate (NMDA) increases nitric oxide synthase (NOS) activity in rat frontal cortex; however, the actual mechanism of this activation has not been addressed. Tetrodotoxin (TTX; 0.05 microM) inhibited NMDA-activated NOS, suggesting that TTX-sensitive Na+ channels are interposed between the NMDA receptors and the NOS cellular compartment. The NMDA response was also blocked by voltage-dependent Ca2+ channel (VDCC) blockers including Cd2+, Co2+, funnel web spider toxin (FTX) and omega-Aga IVa, but not by nifedipine or omega-conotoxin. These data suggest that Ca2+ flux through P- and/or Q-type VDCC subsequent to NMDA-induced depolarization may be at least as important for NOS activation as Ca2+ entry through the NMDA receptor.

  14. Neurological effects of inorganic arsenic exposure: altered cysteine/glutamate transport, NMDA expression and spatial memory impairment.

    PubMed

    Ramos-Chávez, Lucio A; Rendón-López, Christian R R; Zepeda, Angélica; Silva-Adaya, Daniela; Del Razo, Luz M; Gonsebatt, María E

    2015-01-01

    Inorganic arsenic (iAs) is an important natural pollutant. Millions of individuals worldwide drink water with high levels of iAs. Chronic exposure to iAs has been associated with lower IQ and learning disabilities as well as memory impairment. iAs is methylated in tissues such as the brain generating mono and dimethylated species. iAs methylation requires cellular glutathione (GSH), which is the main antioxidant in the central nervous system (CNS). In humans, As species cross the placenta and are found in cord blood. A CD1 mouse model was used to investigate effects of gestational iAs exposure which can lead to oxidative damage, disrupted cysteine/glutamate transport and its putative impact in learning and memory. On postnatal days (PNDs) 1, 15 and 90, the expression of membrane transporters related to GSH synthesis and glutamate transport and toxicity, such as xCT, EAAC1, GLAST and GLT1, as well as LAT1, were analyzed. Also, the expression of the glutamate receptor N-methyl-D-aspartate (NMDAR) subunits NR2A and B as well as the presence of As species in cortex and hippocampus were investigated. On PND 90, an object location task was performed to associate exposure with memory impairment. Gestational exposure to iAs affected the expression of cysteine/glutamate transporters in cortex and hippocampus and induced a negative modulation of NMDAR NR2B subunit in the hippocampus. Behavioral tasks showed significant spatial memory impairment in males while the effect was marginal in females.

  15. Neurological effects of inorganic arsenic exposure: altered cysteine/glutamate transport, NMDA expression and spatial memory impairment

    PubMed Central

    Ramos-Chávez, Lucio A.; Rendón-López, Christian R. R.; Zepeda, Angélica; Silva-Adaya, Daniela; Del Razo, Luz M.; Gonsebatt, María E.

    2015-01-01

    Inorganic arsenic (iAs) is an important natural pollutant. Millions of individuals worldwide drink water with high levels of iAs. Chronic exposure to iAs has been associated with lower IQ and learning disabilities as well as memory impairment. iAs is methylated in tissues such as the brain generating mono and dimethylated species. iAs methylation requires cellular glutathione (GSH), which is the main antioxidant in the central nervous system (CNS). In humans, As species cross the placenta and are found in cord blood. A CD1 mouse model was used to investigate effects of gestational iAs exposure which can lead to oxidative damage, disrupted cysteine/glutamate transport and its putative impact in learning and memory. On postnatal days (PNDs) 1, 15 and 90, the expression of membrane transporters related to GSH synthesis and glutamate transport and toxicity, such as xCT, EAAC1, GLAST and GLT1, as well as LAT1, were analyzed. Also, the expression of the glutamate receptor N-methyl-D-aspartate (NMDAR) subunits NR2A and B as well as the presence of As species in cortex and hippocampus were investigated. On PND 90, an object location task was performed to associate exposure with memory impairment. Gestational exposure to iAs affected the expression of cysteine/glutamate transporters in cortex and hippocampus and induced a negative modulation of NMDAR NR2B subunit in the hippocampus. Behavioral tasks showed significant spatial memory impairment in males while the effect was marginal in females. PMID:25709567

  16. Convulsions induced by centrally administered NMDA in mice: effects of NMDA antagonists, benzodiazepines, minor tranquilizers and anticonvulsants.

    PubMed Central

    Moreau, J. L.; Pieri, L.; Prud'hon, B.

    1989-01-01

    1. Convulsions were induced reproducibly by intracerebroventricular injection of N-methyl-D-aspartic acid (NMDA) to conscious mice. 2. Competitive (carboxypiperazine-propylphosphonic acid, CPP; 2-amino-7-phosphonoheptanoic acid, AP7) and non-competitive (MK801; phencyclidine, PCP; thienylcyclohexylpiperidine, TCP; dextrorphan; dextromethorphan) NMDA antagonists prevented NMDA-induced convulsions. 3. Benzodiazepine receptor agonists and partial agonists (triazolam, diazepam, clonazepam, Ro 16-6028), classical anticonvulsants (diphenylhydantoin, phenobarbitone, sodium valproate) and meprobamate were also found to prevent NMDA-induced convulsions. 4. Flumazenil (a benzodiazepine receptor antagonist) and the GABA agonists THIP and muscimol (up to subtoxic doses) were without effect. 5. Flumazenil reversed the anticonvulsant action of diazepam, but not that of MK801. 6. Results obtained in this model differ somewhat from those described in a seizure model with systemic administration of NMDA. An explanation for this discrepancy is offered. 7. This model is a simple test for assessing the in vivo activity of NMDA antagonists and also expands the battery of chemically-induced seizure models for characterizing anticonvulsants not acting at NMDA receptors. PMID:2574061

  17. GluN2C/GluN2D subunit-selective NMDA receptor potentiator CIQ reverses MK-801-induced impairment in prepulse inhibition and working memory in Y-maze test in mice

    PubMed Central

    Suryavanshi, P S; Ugale, R R; Yilmazer-Hanke, D; Stairs, D J; Dravid, S M

    2014-01-01

    Background and Purpose Despite ample evidence supporting the N-methyl-d-aspartate receptor (NMDAR) hypofunction hypothesis of schizophrenia, progress in the development of effective therapeutics based on this hypothesis has been limited. Facilitation of NMDA receptor function by co-agonists (d-serine or glycine) only partially alleviates the symptoms in schizophrenia; other means to facilitate NMDA receptors are required. NMDA receptor sub-types differ in their subunit composition, with varied GluN2 subunits (GluN2A-GluN2D) imparting different physiological, biochemical and pharmacological properties. CIQ is a positive allosteric modulator that is selective for GluN2C/GluN2D-containing NMDA receptors (Mullasseril et al.). Experimental Approach The effect of systemic administration of CIQ was tested on impairment in prepulse inhibition (PPI), hyperlocomotion and stereotypy induced by i.p. administration of MK-801 and methamphetamine. The effect of CIQ was also tested on MK-801-induced impairment in working memory in Y-maze spontaneous alternation test. Key Results We found that systemic administration of CIQ (20 mg·kg−1, i.p.) in mice reversed MK-801 (0.15 mg·kg−1, i.p.)-induced, but not methamphetamine (3 mg·kg−1, i.p.)-induced, deficit in PPI. MK-801 increased the startle amplitude to pulse alone, which was not reversed by CIQ. In contrast, methamphetamine reduced the startle amplitude to pulse alone, which was reversed by CIQ. CIQ also partially attenuated MK-801- and methamphetamine-induced hyperlocomotion and stereotyped behaviours. Additionally, CIQ reversed the MK-801-induced working memory deficit in spontaneous alternation in a Y-maze. Conclusion and Implications Together, these results suggest that facilitation of GluN2C/GluN2D-containing receptors may serve as an important therapeutic strategy for treating positive and cognitive symptoms in schizophrenia. PMID:24236947

  18. NMDA receptor as a newly identified member of the metabotropic glutamate receptor family: clinical implications for neurodegenerative diseases.

    PubMed

    Chung, ChiHye

    2013-08-01

    Recent reports have proposed a novel function for the N-methyl-D-aspartate (NMDA) receptor (NMDAR), a well-known excitatory, ionotropic receptor. A series of observations employing pharmacological techniques has proposed that upon ligand binding, this ionotropic receptor can actually function via signaling cascades independent of traditional ionotropic action. Moreover, the "metabotropic" action of NMDARs is suggested to mediate a form of synaptic plasticity, namely long-term synaptic depression (LTD), which shares cellular mechanisms with the synaptic deficits observed in Alzheimer's disease. Given that a growing body of clinical and preclinical evidence strongly recommends NMDAR antagonists for their therapeutic potentials and advantages in a variety of diseases, further investigation into their molecular and cellular mechanisms is required to better understand the "metabotropic" action of NMDARs.

  19. NMDA receptor mediates proliferation and CREB phosphorylation in postnatal Müller glia-derived retinal progenitors

    PubMed Central

    Ramírez, Mónica

    2009-01-01

    Purpose Postnatal retinal Müller glia are considered to be retinal progenitors as they retain the ability to dedifferentiate, proliferate, and differentiate to new retinal glia and neurons after injury. The proliferation and differentiation processes are coordinated by several extrinsic factors and neurotransmitters, including glutamate. Thus, the appropriate numbers and proportions of the different cell types are generated to form a functional retina during development and during injury repair. Here we analyze the changes in the proliferation of postnatal Müller glia-derived progenitors after activation of the N-methyl-D-aspartate (NMDA) glutamate receptors. Methods Müller glia-derived progenitor cell cultures were characterized by immunocytochemistry with antibodies against the NR1 subunit of the NMDA receptor and the progenitor cell marker nestin. The effect of glutamate receptor agonists and antagonists on cell proliferation was analyzed by BrdU incorporation or Ki67 immunostaining, cell counting, and by immunolabeling of phosphorylated cAMP response element binding protein (P-CREB) transcription factor. The effect of NMDA receptor activation was analyzed in vivo by P-CREB immunohistochemistry in retinal sections of Long-Evans NMDA injected rats. Results We show that NMDA receptor activation significantly increases the proliferation rate of Müller-glia derived progenitor cells and that this increase can be blocked by NMDA receptor antagonists. Furthermore, we show that CREB phosphorylation is induced in NMDA-treated Müller-glia derived progenitor cells in culture and that specific pharmacological inhibition of CREB phosphorylation results in a decreased number of proliferating cells. We confirmed the relevance of these observations by the analysis of retinal sections after NMDA injection in vivo where immunoreactivity to phosphorylated CREB is also increased after treatment. Conclusions In the present study we show that NMDA receptor activation induces

  20. Observation of the side chain O-methylation of glutamic acid or aspartic acid containing model peptides by electrospray ionization-mass spectrometry.

    PubMed

    Atik, A Emin; Guray, Melda Z; Yalcin, Talat

    2017-03-15

    O-methylation of the side chains of glutamic acid (E) and aspartic acid (D) residues is generally observed modification when an acidified methanol/water (MeOH/dH 2 O) mixture is used as a solvent system during sample preparation for proteomic research. This chemical modification may result misidentification with endogenous protein methylation; therefore, a special care should be taken during sample handling prior to mass spectrometric analysis. In the current study, we systematically examined the extent of E/D methylation and C-terminus carboxyl group of synthetic model peptides in terms of different incubation temperatures, storage times, and added acid types as well as its percentages. To monitor these effects, C-terminus amidated and free acid forms of synthetic model peptides comprised of E or D residue(s) have been analyzed by electrospray ionization-mass spectrometry (ESI-MS). Additionally, LC-MS/MS experiments were performed to confirm the formation of methylated peptide product. The results showed that the rate of methylation was increased as the temperature increases along with prolong incubation times. Moreover, the extent of methylation was remarkably high when formic acid (FA) used as a protonation agent instead of acetic acid (AA). In addition, it was found that the degree of methylation was significantly decreased by lowering acid percentages in ESI solution. More than one acidic residue containing model peptides have been also used to explore the extent of multiple methylation reaction. Lastly, the ethanol (EtOH) and isopropanol (iPrOH) have been substituted separately with MeOH in sample preparation step to investigate the extent of esterification reaction under the same experimental conditions. However, in the positive perspective of view, this method can be used as a simple, rapid and cheap method for methylation of acidic residues under normal laboratory conditions. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Administration of a non-NMDA antagonist, GYKI 52466, increases excitotoxic Purkinje cell degeneration caused by ibogaine.

    PubMed

    O'Hearn, E; Molliver, M E

    2004-01-01

    Ibogaine is a tremorigenic hallucinogen that has been proposed for clinical use in treating addiction. We previously reported that ibogaine, administered systemically, produces degeneration of a subset of Purkinje cells in the cerebellum, primarily within the vermis. Ablation of the inferior olive affords protection against ibogaine-induced neurotoxicity leading to the interpretation that ibogaine itself is not directly toxic to Purkinje cells. We postulated that ibogaine produces sustained excitation of inferior olivary neurons that leads to excessive glutamate release at climbing fiber terminals, causing subsequent excitotoxic injury to Purkinje cells. The neuronal degeneration induced by ibogaine provides an animal model for studying excitotoxic injury in order to analyze the contribution of glutamate receptors to this injury and to evaluate neuroprotective strategies. Since non-N-methyl-D-aspartate (NMDA) receptors mediate Purkinje cell excitation by climbing fibers, we hypothesized that 1-4-aminophenyl-methyl-7,8-methylenedioxy-5H-2,3-benzodiazepine (GYKI-52466), which antagonizes non-NMDA receptors, may have a neuroprotective effect by blocking glutamatergic excitation at climbing fiber synapses. To test this hypothesis, rats were administered systemic ibogaine plus GYKI-52466 and the degree of neuronal injury was analyzed in cerebellar sections. The results indicate that the AMPA antagonist GYKI-52466 (10 mg/kg i.p. x 3) does not protect against Purkinje cell injury at the doses used. Rather, co-administration of GYKI-52466 with ibogaine produces increased toxicity evidenced by more extensive Purkinje cell degeneration. Several hypotheses that may underlie this result are discussed. Although the reason for the increased toxicity found in this study is not fully explained, the present results show that a non-NMDA antagonist can produce increased excitotoxic injury under some conditions. Therefore, caution should be exercised before employing glutamate

  2. Decreased levels of free D-aspartic acid in the forebrain of serine racemase (Srr) knock-out mice.

    PubMed

    Horio, Mao; Ishima, Tamaki; Fujita, Yuko; Inoue, Ran; Mori, Hisashi; Hashimoto, Kenji

    2013-05-01

    d-Serine, an endogenous co-agonist of the N-methyl-d-aspartate (NMDA) receptor is synthesized from l-serine by serine racemase (SRR). A previous study of Srr knockout (Srr-KO) mice showed that levels of d-serine in forebrain regions, such as frontal cortex, hippocampus, and striatum, but not cerebellum, of mutant mice are significantly lower than those of wild-type (WT) mice, suggesting that SRR is responsible for d-serine production in the forebrain. In this study, we attempted to determine whether SRR affects the level of other amino acids in brain tissue. We found that tissue levels of d-aspartic acid in the forebrains (frontal cortex, hippocampus and striatum) of Srr-KO mice were significantly lower than in WT mice, whereas levels of d-aspartic acid in the cerebellum were not altered. Levels of d-alanine, l-alanine, l-aspartic acid, taurine, asparagine, arginine, threonine, γ-amino butyric acid (GABA) and methionine, remained the same in frontal cortex, hippocampus, striatum and cerebellum of WT and mutant mice. Furthermore, no differences in d-aspartate oxidase (DDO) activity were detected in the forebrains of WT and Srr-KO mice. These results suggest that SRR and/or d-serine may be involved in the production of d-aspartic acid in mouse forebrains, although further detailed studies will be necessary to confirm this finding. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. The NMDA antagonist ketamine and the 5-HT agonist psilocybin produce dissociable effects on structural encoding of emotional face expressions.

    PubMed

    Schmidt, André; Kometer, Michael; Bachmann, Rosilla; Seifritz, Erich; Vollenweider, Franz

    2013-01-01

    Both glutamate and serotonin (5-HT) play a key role in the pathophysiology of emotional biases. Recent studies indicate that the glutamate N-methyl-D-aspartate (NMDA) receptor antagonist ketamine and the 5-HT receptor agonist psilocybin are implicated in emotion processing. However, as yet, no study has systematically compared their contribution to emotional biases. This study used event-related potentials (ERPs) and signal detection theory to compare the effects of the NMDA (via S-ketamine) and 5-HT (via psilocybin) receptor system on non-conscious or conscious emotional face processing biases. S-ketamine or psilocybin was administrated to two groups of healthy subjects in a double-blind within-subject placebo-controlled design. We behaviorally assessed objective thresholds for non-conscious discrimination in all drug conditions. Electrophysiological responses to fearful, happy, and neutral faces were subsequently recorded with the face-specific P100 and N170 ERP. Both S-ketamine and psilocybin impaired the encoding of fearful faces as expressed by a reduced N170 over parieto-occipital brain regions. In contrast, while S-ketamine also impaired the encoding of happy facial expressions, psilocybin had no effect on the N170 in response to happy faces. This study demonstrates that the NMDA and 5-HT receptor systems differentially contribute to the structural encoding of emotional face expressions as expressed by the N170. These findings suggest that the assessment of early visual evoked responses might allow detecting pharmacologically induced changes in emotional processing biases and thus provides a framework to study the pathophysiology of dysfunctional emotional biases.

  4. Abnormality in glutamine-glutamate cycle in the cerebrospinal fluid of cognitively intact elderly individuals with major depressive disorder: a 3-year follow-up study.

    PubMed

    Hashimoto, K; Bruno, D; Nierenberg, J; Marmar, C R; Zetterberg, H; Blennow, K; Pomara, N

    2016-03-01

    Major depressive disorder (MDD), common in the elderly, is a risk factor for dementia. Abnormalities in glutamatergic neurotransmission via the N-methyl-D-aspartate receptor (NMDA-R) have a key role in the pathophysiology of depression. This study examined whether depression was associated with cerebrospinal fluid (CSF) levels of NMDA-R neurotransmission-associated amino acids in cognitively intact elderly individuals with MDD and age- and gender-matched healthy controls. CSF was obtained from 47 volunteers (MDD group, N=28; age- and gender-matched comparison group, N=19) at baseline and 3-year follow-up (MDD group, N=19; comparison group, N=17). CSF levels of glutamine, glutamate, glycine, L-serine and D-serine were measured by high-performance liquid chromatography. CSF levels of amino acids did not differ across MDD and comparison groups. However, the ratio of glutamine to glutamate was significantly higher at baseline in subjects with MDD than in controls. The ratio decreased in individuals with MDD over the 3-year follow-up, and this decrease correlated with a decrease in the severity of depression. No correlations between absolute amino-acid levels and clinical variables were observed, nor were correlations between amino acids and other biomarkers (for example, amyloid-β42, amyloid-β40, and total and phosphorylated tau protein) detected. These results suggest that abnormalities in the glutamine-glutamate cycle in the communication between glia and neurons may have a role in the pathophysiology of depression in the elderly. Furthermore, the glutamine/glutamate ratio in CSF may be a state biomarker for depression.

  5. The influence of ionotropic and metabotropic glutamate receptor ligands on anxiety-like effect of amphetamine withdrawal in rats.

    PubMed

    Koltunowska, D; Gibula-Bruzda, E; Kotlinska, J H

    2013-08-01

    Chronic amphetamine use results in anxiety-like states after drug cessation. The aim of the study was to determine a role of ionotropic and metabotropic glutamate receptor ligands in amphetamine-evoked withdrawal anxiety in the elevated plus-maze test in rats. In our study memantine (8 and 12 mg/kg), a noncompetitive N-methyl-d-aspartate (NMDA) receptor antagonist did not reduce amphetamine withdrawal anxiety. Acamprosate (NMDA and metabotropic glutamate 5 receptor (mGluR5) antagonist) at the dose 200 and 400mg/kg showed anxiolytic-like effect, thus increasing the percent of time spent in open arms and a number of open arm entries. mGluR5 selective antagonist, MTEP (3-[(2-methyl-1,3-thiazol-4-yl)ethynyl]pyridine hydrochloride) and mGluR2/3 agonist, LY354740 (1S,2S,5R,6S)-2-aminobicyclo[3.1.0]hexane-2,6-dicarboxylic acid), caused effects similar to acamprosate at doses 1.25-5mg/kg and 2.5-5mg/kg, respectively. None of the glutamate ligands influenced locomotor activity of rats when given to the saline-treated group. Taking into account the positive correlation between amphetamine withdrawal-induced anxiety and relapse to amphetamine taking, our results suggest that modulation of mGluRs may prevent relapse to amphetamine and might pose a new direction in amphetamine abuse therapy. Copyright © 2013 Elsevier Inc. All rights reserved.

  6. GluN2B-containing NMDA receptors and AMPA receptors in medial prefrontal cortex are necessary for odor span in rats.

    PubMed

    Davies, Don A; Greba, Quentin; Howland, John G

    2013-01-01

    Working memory is a type of short-term memory involved in the maintenance and manipulation of information essential for complex cognition. While memory span capacity has been extensively studied in humans as a measure of working memory, it has received considerably less attention in rodents. Our aim was to examine the role of the N-methyl-D-aspartate (NMDA) and α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) glutamate receptors in odor span capacity using systemic injections or infusions of receptor antagonists into the medial prefrontal cortex (mPFC). Long Evans rats were trained on a well-characterized odor span task (OST). Initially, rats were trained to dig for a food reward in sand followed by training on a non-match to sample discrimination using sand scented with household spices. The rats were then required to perform a serial delayed non-match to sample procedure which was their odor span. Systemic injection of the broad spectrum NMDA receptor antagonist 3-(2-Carboxypiperazin-4-yl)propyl-1-phosphonic acid (CPP) (10 mg/kg) or the GluN2B-selective antagonist Ro 25-6981 (10 mg/kg but not 6 mg/kg) significantly reduced odor span capacity. Infusions of the GluN2B- selective antagonist Ro 25-6981 (2.5 μg/hemisphere) into mPFC reduced span capacity, an effect that was nearly significant (p = 0.069). Infusions of the AMPA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) (1.25 μg/hemisphere) into mPFC reduced span capacity and latency for the rats to make a choice in the task. These results demonstrate span capacity in rats depends on ionotropic glutamate receptor activation in the mPFC. Further understanding of the circuitry underlying span capacity may aid in the novel therapeutic drug development for persons with working memory impairments as a result of disorders such as schizophrenia and Alzheimer's disease.

  7. 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.

  8. Olanzapine Reverses MK-801-Induced Cognitive Deficits and Region-Specific Alterations of NMDA Receptor Subunits

    PubMed Central

    Liu, Xiao; Li, Jitao; Guo, Chunmei; Wang, Hongli; Sun, Yaxin; Wang, Han; Su, Yun-Ai; Li, Keqing; Si, Tianmei

    2018-01-01

    Cognitive dysfunction constitutes an essential component in schizophrenia for its early presence in the pathophysiology of the disease and close relatedness to life quality of patients. To develop effective treatment of cognitive deficits, it is important to understand their neurobiological causes and to identify potential therapeutic targets. In this study, adopting repeated MK-801 treatment as an animal model of schizophrenia, we investigated whether antipsychotic drugs, olanzapine and haloperidol, can reverse MK-801-induced cognitive deficits and how the reversal processes recruited proteins involved in glutamate neurotransmission in rat medial prefrontal cortex (mPFC) and hippocampus. We found that low-dose chronic MK-801 treatment impaired object-in-context recognition memory and reversal learning in the Morris water maze, leaving reference memory relatively unaffected, and that these cognitive deficits can be partially reversed by olanzapine, not haloperidol, treatment. At the molecular level, chronic MK-801 treatment resulted in the reduction of multiple N-methyl-D-aspartate (NMDA) receptor subunits in rat mPFC and olanzapine, not haloperidol, treatment restored the levels of GluN1 and phosphorylated GluN2B in this region. Taken together, MK-801-induced cognitive deficits may be associated with region-specific changes in NMDA receptor subunits and the reversal of specific NMDA receptor subunits may underlie the cognition-enhancing effects of olanzapine. PMID:29375333

  9. 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…

  10. NMDA channel gating is influenced by a tryptophan residue in the M2 domain but calcium permeation is not altered.

    PubMed Central

    Buck, D P; Howitt, S M; Clements, J D

    2000-01-01

    N-Methyl-D-aspartate (NMDA) receptors are susceptible to open-channel block by dizolcipine (MK-801), ketamine and Mg(2+) and are permeable to Ca(2+). It is thought that a tryptophan residue in the second membrane-associated domain (M2) may form part of the binding site for open-channel blockers and contribute to Ca(2+) permeability. We tested this hypothesis using recombinant wild-type and mutant NMDA receptors expressed in HEK-293 cells. The tryptophan was mutated to a leucine (W-5L) in both the NMDAR1 and NMDAR2A subunits. MK-801 and ketamine progressively inhibited currents evoked by glutamate, and the rate of inhibition was increased by the W-5L mutation. An increase in open channel probability accounted for the acceleration. Fluctuation analysis of the glutamate-evoked current revealed that the NMDAR1 W-5L mutation increased channel mean open time, providing further evidence for an alteration in gating. However, the equilibrium affinities of Mg(2+) and ketamine were largely unaffected by the W-5L mutation, and Ca(2+) permeability was not decreased. Therefore, the M2 tryptophan residue of the NMDA channel is not involved in Ca(2+) permeation or the binding of open-channel blockers, but plays an important role in channel gating. PMID:11053122

  11. Relationship of resting brain hyperconnectivity and schizophrenia-like symptoms produced by the NMDA receptor antagonist ketamine in humans.

    PubMed

    Driesen, N R; McCarthy, G; Bhagwagar, Z; Bloch, M; Calhoun, V; D'Souza, D C; Gueorguieva, R; He, G; Ramachandran, R; Suckow, R F; Anticevic, A; Morgan, P T; Krystal, J H

    2013-11-01

    N-methyl-D-aspartate glutamate receptor (NMDA-R) antagonists produce schizophrenia-like positive and negative symptoms in healthy human subjects. Preclinical research suggests that NMDA-R antagonists interfere with the function of gamma-aminobutyric acid (GABA) neurons and alter the brain oscillations. These changes have been hypothesized to contribute to psychosis. In this investigation, we evaluated the hypothesis that the NMDA-R antagonist ketamine produces alterations in cortical functional connectivity during rest that are related to symptoms. We administered ketamine to a primary sample of 22 subjects and to an additional, partially overlapping, sample of 12 subjects. Symptoms before and after the experimental session were rated with the Positive and Negative Syndrome Scale (PANSS). In the primary sample, functional connectivity was measured via functional magnetic resonance imaging almost immediately after infusion began. In the additional sample, this assessment was repeated after 45 min of continuous ketamine infusion. Global, enhanced functional connectivity was observed at both timepoints, and this hyperconnectivity was related to symptoms in a region-specific manner. This study supports the hypothesis that pathological increases in resting brain functional connectivity contribute to the emergence of positive and negative symptoms associated with schizophrenia.

  12. Relationship of Resting Brain Hyperconnectivity and Schizophrenia-like Symptoms Produced by the NMDA receptor Antagonist Ketamine in Humans

    PubMed Central

    Driesen, Naomi R.; McCarthy, Gregory; Bhagwagar, Zubin; Bloch, Michael; Calhoun, Vincent; D’Souza, Deepak C.; Gueorguieva, Ralitza; He, George; Ramachandran, Ramani; Suckow, Raymond F.; Anticevic, Alan; Morgan, Peter T.; Krystal, John H.

    2012-01-01

    N-methyl-D-aspartate glutamate receptor (NMDA-R) antagonists produce schizophrenia-like positive and negative symptoms in healthy human subjects. Preclinical research suggests that NMDA-R antagonists interfere with the function of gamma-aminobutyric acid (GABA) neurons and alter brain oscillations. These changes have been hypothesized to contribute to psychosis. In this investigation, we evaluated the hypothesis that the NMDA-R antagonist ketamine produces alterations in cortical functional connectivity during rest that are related to symptoms. We administered ketamine to a primary sample of twenty-two subjects and to an additional, partially overlapping, sample of twelve subjects. Symptoms before and after the experimental session were rated with the Positive and Negative Symptom Scale (PANSS). In the primary sample, functional connectivity was measured via functional magnetic resonance imaging almost immediately after infusion began. In the additional sample, this assessment was repeated after 45 minutes of continuous ketamine infusion. Global, enhanced functional connectivity was observed at both timepoints and this hyperconnectivity was related to symptoms in a region-specific manner. This study supports the hypothesis that pathological increases in resting brain functional connectivity contribute to the emergence of positive and negative symptoms associated with schizophrenia. PMID:23337947

  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.

  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. [NO donors transform neuronal response to glutamate].

    PubMed

    D'iakonova, T L

    1998-10-01

    Electrophysiological experiments on three identified neurones were performed. Two NO donors, sodium nitroprusside (SNP) and sodium nitrite, as well as NO synthase inhibitor, were used. In each neurone, bath application of glutamate caused hyperpolarization and suppression of firing. Combined application of glutamate and SNP resulted in that the same cells responded to identical glutamate solutions with depolarization and excitation. Application of N-monomethyl-L-arginin (NMMA) arrested the glutamate-induced firing and depolarization. The findings suggest involvement of NO in the mechanism of transformation of glutamate-induced inhibition into excitation and a mediation of the latter by the N-methyl-D-aspartate-like receptors in the Helix brain.

  16. Changes in D-aspartic acid and D-glutamic acid levels in the tissues and physiological fluids of mice with various D-aspartate oxidase activities.

    PubMed

    Han, Hai; Miyoshi, Yurika; Koga, Reiko; Mita, Masashi; Konno, Ryuichi; Hamase, Kenji

    2015-12-10

    D-Aspartic acid (D-Asp) and D-glutamic acid (D-Glu) are currently paid attention as modulators of neuronal transmission and hormonal secretion. These two D-amino acids are metabolized only by D-aspartate oxidase (DDO) in mammals. Therefore, in order to design and develop new drugs controlling the D-Asp and D-Glu amounts via regulation of the DDO activities, changes in these acidic D-amino acid amounts in various tissues are expected to be clarified in model animals having various DDO activities. In the present study, the amounts of Asp and Glu enantiomers in 6 brain tissues, 11 peripheral tissues and 2 physiological fluids of DDO(+/+), DDO(+/-) and DDO(-/-) mice were determined using a sensitive and selective two-dimensional HPLC system. As a result, the amounts of D-Asp were drastically increased with the decrease in the DDO activity in all the tested tissues and physiological fluids. On the other hand, the amounts of D-Glu were almost the same among the 3 strains of mice. The present results are useful for designing new drug candidates, such as DDO inhibitors, and further studies are expected. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Inflammatory sensitization of nociceptors depends on activation of NMDA receptors in DRG satellite cells.

    PubMed

    Ferrari, Luiz Fernando; Lotufo, Celina Monteiro; Araldi, Dionéia; Rodrigues, Marcos A; Macedo, Larissa P; Ferreira, Sérgio H; Parada, Carlos Amilcar

    2014-12-23

    The present study evaluated the role of N-methyl-D-aspartate receptors (NMDARs) expressed in the dorsal root ganglia (DRG) in the inflammatory sensitization of peripheral nociceptor terminals to mechanical stimulation. Injection of NMDA into the fifth lumbar (L5)-DRG induced hyperalgesia in the rat hind paw with a profile similar to that of intraplantar injection of prostaglandin E2 (PGE2), which was significantly attenuated by injection of the NMDAR antagonist D(-)-2-amino-5-phosphonopentanoic acid (D-AP-5) in the L5-DRG. Moreover, blockade of DRG AMPA receptors by the antagonist 6,7-dinitroquinoxaline-2,3-dione had no effect in the PGE2-induced hyperalgesia in the paw, showing specific involvement of NMDARs in this modulatory effect and suggesting that activation of NMDAR in the DRG plays an important role in the peripheral inflammatory hyperalgesia. In following experiments we observed attenuation of PGE2-induced hyperalgesia in the paw by the knockdown of NMDAR subunits NR1, NR2B, NR2D, and NR3A with antisense-oligodeoxynucleotide treatment in the DRG. Also, in vitro experiments showed that the NMDA-induced sensitization of cultured DRG neurons depends on satellite cell activation and on those same NMDAR subunits, suggesting their importance for the PGE2-induced hyperalgesia. In addition, fluorescent calcium imaging experiments in cultures of DRG cells showed induction of calcium transients by glutamate or NMDA only in satellite cells, but not in neurons. Together, the present results suggest that the mechanical inflammatory nociceptor sensitization is dependent on glutamate release at the DRG and subsequent NMDAR activation in satellite glial cells, supporting the idea that the peripheral hyperalgesia is an event modulated by a glutamatergic system in the DRG.

  18. Effects of GABA and bicuculline on N-methyl-D-aspartate- and quisqualate-induced reductions in extracellular free calcium in area CA1 of the hippocampal slice.

    PubMed

    Hamon, B; Heinemann, U

    1986-01-01

    Decreases in extracellular free calcium ([Ca2+]o) and concomitant field potentials were recorded from the dendritic and cell body layers of the CA1 field in transverse hippocampal slices. They were elicited by tetanic stimulation of Schaffer collaterals and commissural fibers or by iontophoretic application of the excitatory amino acids N-methyl-D-aspartate (NMDA) and quisqualate (Quis). Under control conditions, decreases in [Ca2+]o were found to be maximal in stratum pyramidale (SP). In stratum radiatum (SR), 100 micron away from SP, decreases in [Ca2+]o were half the size of those observed in SP. Bicuculline methiodide, bath-applied at concentrations of 10-100 microM, enhanced the reductions in [Ca2+]o, increased the field potentials in all layers and also induced "spontaneous" epileptiform activity. In the presence of bicuculline, the decreases in [Ca2+]o were particularly enhanced in SR and were often greater than those recorded in SP. This was the case for changes in [Ca2+]o induced either by repetitive electrical stimulation or by application of NMDA and Quis. When synaptic transmission was blocked by perfusing the slices with a low Ca2+ medium, all NMDA and Quis-induced changes in [Ca2+]o were predictably reduced but there was a relative enhancement of changes in [Ca2+]o in SR with respect to those in SP. We propose that, under normal conditions, an inhibitory control mediated by GABA limits the reductions of [Ca2+]o particularly in SR. In support of this proposal, we found that bath-applied GABA had a depressant action on changes in [Ca2+]o.

  19. Dissociation of thirst and sodium appetite in the furo/cap model of extracellular dehydration and a role for N-methyl-D-aspartate receptors in the sensitization of sodium appetite

    PubMed Central

    Hurley, Seth. W.; Johnson, Alan Kim

    2015-01-01

    Depletion of extracellular fluids motivates many animals to seek out and ingest water and sodium. Animals with a history of extracellular dehydration display enhanced sodium appetite and in some cases thirst. The progressive increase in sodium intake induced by repeated sodium depletions is known as sensitization of sodium appetite. Administration of the diuretic and natriuretic drug, furosemide, along with a low dose of captopril (furo/cap), elicits thirst and a rapid onset of sodium appetite. In the present studies the furo/cap model was used to explore the physiological mechanisms of sensitization of sodium appetite. However, when thirst and sodium appetite were measured concurrently in the furo/cap model, individual rats exhibited sensitization of either thirst or sodium appetite. In subsequent studies, thirst and sodium appetite were dissociated by offering either water prior to sodium or sodium before water. When water and sodium intake were dissociated in time, the furo/cap model reliably produced sensitization of sodium appetite. It is likely that neuroplasticity mediates this sensitization. Glutamatergic N-methyl-d-aspartate receptor (NMDA-R) activation is critical for the development of most forms of neuroplasticity. Therefore, we hypothesized that integrity of NMDA-R function is necessary for the sensitization of sodium appetite. Pharmacological blockade of NMDA-Rs with systemic administration of MK-801 (0.15mg/kg) prevented the sensitization of fluid intake in general when water and sodium were offered concurrently, and prevented sensitization of sodium intake specifically when water and sodium intake were dissociated. The involvement of NMDA-Rs provides support for the possibility that sensitization of sodium appetite is mediated by neuroplasticity. PMID:24341713

  20. NMDA Receptor as a Newly Identified Member of the Metabotropic Glutamate Receptor Family: Clinical Implications for Neurodegenerative Diseases

    PubMed Central

    Chung, ChiHye

    2013-01-01

    Recent reports have proposed a novel function for the N-methyl-d-aspartate (NMDA) receptor (NMDAR), a well-known excitatory, ionotropic receptor. A series of observations employing pharmacological techniques has proposed that upon ligand binding, this ionotropic receptor can actually function via signaling cascades independent of traditional ionotropic action. Moreover, the “metabotropic” action of NMDARs is suggested to mediate a form of synaptic plasticity, namely long-term synaptic depression (LTD), which shares cellular mechanisms with the synaptic deficits observed in Alzheimer’s disease. Given that a growing body of clinical and preclinical evidence strongly recommends NMDAR antagonists for their therapeutic potentials and advantages in a variety of diseases, further investigation into their molecular and cellular mechanisms is required to better understand the “metabotropic” action of NMDARs. PMID:23740429

  1. Expression of specific ionotropic glutamate and GABA-A receptor subunits is decreased in central amygdala of alcoholics.

    PubMed

    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.

  2. 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

  3. 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…

  4. NMDA-receptor blockade by CPP impairs post-training consolidation of a rapidly acquired spatial representation in rat hippocampus.

    PubMed

    McDonald, Robert J; Hong, Nancy S; Craig, Laura A; Holahan, Matthew R; Louis, Meira; Muller, Robert U

    2005-09-01

    Recent evidence suggests that N-methyl-D-aspartate (NMDA)-receptor mediated plasticity in hippocampus has a more subtle role in memory-based behaviours than originally thought. One idea is that NMDA-based plasticity is essential for the consolidation of post-training memory but not for the initial encoding or for short-term memory. To further test this idea we used a three-phase variant of the hidden goal water maze task. In the first phase, rats were pre-trained to an initial location. Next, intense, massed training was done in a 2-h interval to teach the rats to go to a new location after either an injection of the NMDA receptor antagonist (6)-3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid (CPP) or of vehicle. Finally, under drug-free conditions 24 h after new location training, a competition test was done between the original and new locations. We find that N-methyl-D-aspartate (NMDA)-receptor blockade has little or no effect on new location training. In contrast, when tested 24 h later, the strength of the trace for the new location learned during NMDA-receptor blockade was much weaker compared with the trace for the new location learned after saline injection. Further experiments showed similar effects when NMDA-receptors were blocked immediately after the new location training, suggesting that this is a memory consolidation effect. Our results therefore reinforce the notion that hippocampal NMDA-receptors participate in post-training memory consolidation but are not essential for the processes necessary to learn or retain navigational information in the short term.

  5. 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...

  6. Characterization of Human Hippocampal Neural Stem/Progenitor Cells and Their Application to Physiologically Relevant Assays for Multiple Ionotropic Glutamate Receptors.

    PubMed

    Fukushima, Kazuyuki; Tabata, Yoshikuni; Imaizumi, Yoichi; Kohmura, Naohiro; Sugawara, Michiko; Sawada, Kohei; Yamazaki, Kazuto; Ito, Masashi

    2014-09-01

    The hippocampus is an important brain region that is involved in neurological disorders such as Alzheimer disease, schizophrenia, and epilepsy. Ionotropic glutamate receptors-namely,N-methyl-D-aspartate (NMDA) receptors (NMDARs), α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptors (AMPARs), and kainic acid (KA) receptors (KARs)-are well known to be involved in these diseases by mediating long-term potentiation, excitotoxicity, or both. To predict the therapeutic efficacy and neuronal toxicity of drug candidates acting on these receptors, physiologically relevant systems for assaying brain region-specific human neural cells are necessary. Here, we characterized the functional differentiation of human fetal hippocampus-derived neural stem/progenitor cells-namely, HIP-009 cells. Calcium rise assay demonstrated that, after a 4-week differentiation, the cells responded to NMDA (EC50= 7.5 ± 0.4 µM; n= 4), AMPA (EC50= 2.5 ± 0.1 µM; n= 3), or KA (EC50= 33.5 ± 1.1 µM; n= 3) in a concentration-dependent manner. An AMPA-evoked calcium rise was observed in the absence of the desensitization inhibitor cyclothiazide. In addition, the calcium rise induced by these agonists was inhibited by antagonists for each receptor-namely, MK-801 for NMDA stimulation (IC50= 0.6 ± 0.1 µM; n= 4) and NBQX for AMPA and KA stimulation (IC50= 0.7 ± 0.1 and 0.7 ± 0.03 µM, respectively; n= 3). The gene expression profile of differentiated HIP-009 cells was distinct from that of undifferentiated cells and closely resembled that of the human adult hippocampus. Our results show that HIP-009 cells are a unique tool for obtaining human hippocampal neural cells and are applicable to systems for assay of ionotropic glutamate receptors as a physiologically relevant in vitro model. © 2014 Society for Laboratory Automation and Screening.

  7. Nitric Oxide Mediates Glutamate-Linked Enhancement of cGMP Levels in the Cerebellum

    NASA Astrophysics Data System (ADS)

    Bredt, David S.; Snyder, Solomon H.

    1989-11-01

    Nitric oxide, which mediates influences of numerous neurotransmitters and modulators on vascular smooth muscle and leukocytes, can be formed in the brain from arginine by an enzymatic activity that stoichiometrically generates citrulline. We show that glutamate and related amino acids, such as N-methyl-D-aspartate, markedly stimulate arginine-citrulline transformation in cerebellar slices stoichiometrically with enhancement of cGMP levels. Nω-monomethyl-L-arginine blocks the augmentation both of citrulline and cGMP with identical potencies. Arginine competitively reverses both effects of Nω-monomethyl-L-arginine with the same potencies. Hemoglobin, which complexes nitric oxide, prevents the stimulation by N-methyl-D-aspartate of cGMP levels, and superoxide dismutase, which elevates nitric oxide levels, increases cGMP formation. These data establish that nitric oxide mediates the stimulation by glutamate of cGMP formation.

  8. NMDA and D2-like receptors modulate cognitive flexibility in a color discrimination reversal task in pigeons.

    PubMed

    Herold, Christina

    2010-06-01

    Reversal and extinction learning represent forms of cognitive flexibility that refer to the ability of an animal to alter behavior in response to unanticipated changes on environmental demands. A role for dopamine and glutamate in modulating this behavior has been implicated. Here, we determined the effects of intracerebroventricular injections in pigeons' forebrain of the D2-like receptor agonist quinpirole, the D2-like receptor antagonist sulpiride and the N-methyl-d-aspartate receptor antagonist AP-5 on initial acquisition and reversal of a color discrimination task. On day one, pigeons had to learn to discriminate two color keys. On day two, pigeons first performed a retention test, which was followed by a reversal of the reward contingencies of the two color keys. None of the drugs altered performance in the initial acquisition of color discrimination or affected the retention of the learned color key. In contrast, all drugs impaired reversal learning by increasing trials and incorrect responses in the reversal session. Our data support the hypothesis that D2-like receptor mechanisms, like N-methyl-d-aspartate receptor modulations, are involved in cognitive flexibility and relearning processes, but not in initial learning of stimulus-reward association.

  9. Neuroprotective Effects of Glutamate Antagonists and Extracellular Acidity

    NASA Astrophysics Data System (ADS)

    Kaku, David A.; Giffard, Rona G.; Choi, Dennis W.

    1993-06-01

    Glutamate antagonists protect neurons from hypoxic injury both in vivo and in vitro, but in vitro studies have not been done under the acidic conditions typical of hypoxia-ischemia in vivo. Consistent with glutamate receptor antagonism, extracellular acidity reduced neuronal death in murine cortical cultures that were deprived of oxygen and glucose. Under these acid conditions, N-methyl-D-aspartate and α-amino-3-hydroxy-5-methyl-4-isox-azolepropionate-kainate antagonists further reduced neuronal death, such that some neurons tolerated prolonged oxygen and glucose deprivation almost as well as did astrocytes. Neuroprotection induced by this combination exceeded that induced by glutamate antagonists alone, suggesting that extracellular acidity has beneficial effects beyond the attenuation of ionotropic glutamate receptor activation.

  10. Ventral tegmental ionotropic glutamate receptor stimulation of nucleus accumbens tonic dopamine efflux blunts hindbrain-evoked phasic neurotransmission: implications for dopamine dysregulation disorders.

    PubMed

    Tye, S J; Miller, A D; Blaha, C D

    2013-11-12

    Activation of glutamate receptors within the ventral tegmental area (VTA) stimulates extrasynaptic (basal) dopamine release in terminal regions, including the nucleus accumbens (NAc). Hindbrain inputs from the laterodorsal tegmental nucleus (LDT) are critical for elicitation of phasic VTA dopamine cell activity and consequent transient dopamine release. This study investigated the role of VTA ionotropic glutamate receptor (iGluR) stimulation on both basal and LDT electrical stimulation-evoked dopamine efflux in the NAc using in vivo chronoamperometry and fixed potential amperometry in combination with stearate-graphite paste and carbon fiber electrodes, respectively. Intra-VTA infusion of the iGluR agonists (±)-α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA; 1 μg/μl) or N-methyl-d-aspartic acid (NMDA; 2 μg/μl) enhanced basal NAc dopamine efflux. This iGluR-mediated potentiation of basal dopamine efflux was paralleled by an attenuation of LDT-evoked transient NAc dopamine efflux, suggesting that excitation of basal activity effectively inhibited the capacity of hindbrain afferents to elicit transient dopamine efflux. In line with this, post-NMDA infusion of the dopamine D2 autoreceptor (D2R) agonist quinpirole (1 μg/μl; intra-VTA) partially recovered NMDA-mediated attenuation of LDT-evoked NAc dopamine, while concurrently attenuating NMDA-mediated potentiation of basal dopamine efflux. Post-NMDA infusion of quinpirole (1 μg/μl) alone attenuated basal and LDT-evoked dopamine efflux. Taken together, these data reveal that hyperstimulation of basal dopamine transmission can stunt hindbrain burst-like stimulation-evoked dopamine efflux. Inhibitory autoreceptor mechanisms within the VTA help to partially recover the magnitude of phasic dopamine efflux, highlighting the importance of both iGluRs and D2 autoreceptors in maintaining the functional balance of tonic and phasic dopamine neurotransmission. Dysregulation of this balance may have important

  11. A new and specific non-NMDA receptor antagonist, FG 9065, blocks L-AP4-evoked depolarization in rat cerebral cortex.

    PubMed

    Sheardown, M J

    1988-04-13

    L(+)-AP4 (2-amino-4-phosphonobutyrate) depolarized slices of rat cerebral cortex, when applied following a 2 min priming application of quisqualate. This response diminishes with time and is not seen after NMDA application. A new selective non-N-methyl-D-aspartate (NMDA) antagonist, 6-cyano-7-nitro-2,3-dihydroxyquinoxaline (FG 9065), inhibits the L(+)-AP4 depolarization. It is argued that the response is mediated indirectly by postsynaptic quisqualate receptors.

  12. Differential regulation of NMDA receptor-expressing neurons in the rat hippocampus and striatum following bilateral vestibular loss demonstrated using flow cytometry.

    PubMed

    Benoit, Alice; Besnard, Stephane; Guillamin, Maryline; Philoxene, Bruno; Sola, Brigitte; Le Gall, Anne; Machado, Marie-Laure; Toulouse, Joseph; Hitier, Martin; Smith, Paul F

    2018-06-21

    There is substantial evidence that loss of vestibular function impairs spatial learning and memory related to hippocampal (HPC) function, as well as increasing evidence that striatal (Str) plasticity is also implicated. Since the N-methyl-D-aspartate (NMDA) subtype of glutamate receptor is considered essential to spatial memory, previous studies have investigated whether the expression of HPC NMDA receptors changes following vestibular loss; however, the results have been contradictory. Here we used a novel flow cytometric method to quantify the number of neurons expressing NMDA receptors in the HPC and Str following bilateral vestibular loss (BVL) in rats. At 7 and 30 days post-op., there was a significant increase in the number of HPC neurons expressing NMDA receptors in the BVL animals, compared to sham controls (P ≤ 0.004 and P ≤ 0.0001, respectively). By contrast, in the Str, at 7 days there was a significant reduction in the number of neurons expressing NMDA receptors in the BVL group (P ≤ 0.05); however, this difference had disappeared by 30 days post-op. These results suggest that BVL causes differential changes in the number of neurons expressing NMDA receptors in the HPC and Str, which may be related to its long-term impairment of spatial memory. Copyright © 2018. Published by Elsevier B.V.

  13. Selective Impairment of Spatial Cognition Caused by Autoantibodies to the N-Methyl-d-Aspartate Receptor

    PubMed Central

    Chang, Eric H.; Volpe, Bruce T.; Mackay, Meggan; Aranow, Cynthia; Watson, Philip; Kowal, Czeslawa; Storbeck, Justin; Mattis, Paul; Berlin, RoseAnn; Chen, Huiyi; Mader, Simone; Huerta, Tomás S.; Huerta, Patricio T.; Diamond, Betty

    2015-01-01

    Patients with systemic lupus erythematosus (SLE) experience cognitive abnormalities in multiple domains including processing speed, executive function, and memory. Here we show that SLE patients carrying antibodies that bind DNA and the GluN2A and GluN2B subunits of the N-methyl-d-aspartate receptor (NMDAR), termed DNRAbs, displayed a selective impairment in spatial recall. Neural recordings in a mouse model of SLE, in which circulating DNRAbs penetrate the hippocampus, revealed that CA1 place cells exhibited a significant expansion in place field size. Structural analysis showed that hippocampal pyramidal cells had substantial reductions in their dendritic processes and spines. Strikingly, these abnormalities became evident at a time when DNRAbs were no longer detectable in the hippocampus. These results suggest that antibody-mediated neurocognitive impairments may be highly specific, and that spatial cognition may be particularly vulnerable to DNRAb-mediated structural and functional injury to hippocampal cells that evolves after the triggering insult is no longer present. PMID:26286205

  14. Positive Modulators of the N-Methyl-d-aspartate Receptor: Structure-Activity Relationship Study of Steroidal 3-Hemiesters.

    PubMed

    Krausova, Barbora; Slavikova, Barbora; Nekardova, Michaela; Hubalkova, Pavla; Vyklicky, Vojtech; Chodounska, Hana; Vyklicky, Ladislav; Kudova, Eva

    2018-05-24

    Here, we report the synthesis of pregn-5-ene and androst-5-ene dicarboxylic acid esters and explore the structure-activity relationship (SAR) for their modulation of N-methyl-d-aspartate receptors (NMDARs). All compounds were positive modulators of recombinant GluN1/GluN2B receptors (EC 50 varying from 1.8 to 151.4 μM and E max varying from 48% to 452%). Moreover, 10 compounds were found to be more potent GluN1/GluN2B receptor modulators than endogenous pregnenolone sulfate (EC 50 = 21.7 μM). The SAR study revealed a relationship between the length of the residues at carbon C-3 of the steroid molecule and the positive modulatory effect at GluN1/GluN2B receptors for various D-ring modifications. A selected compound, 20-oxo-pregnenolone hemiadipate, potentiated native NMDARs to a similar extent as GluN1/GluN2A-D receptors and inhibited AMPARs and GABA A R responses. These results provide a unique opportunity for the development of new steroid based drugs with potential use in the treatment of neuropsychiatric disorders involving hypofunction of NMDARs.

  15. NMDA inhibits oxotremorine-induced acid secretion via the NO-dependent cyclic GMP system in rat stomach.

    PubMed

    Tsai, L H; Lee, Y J

    2001-12-31

    The mechanism of N-methyl-D-aspartate (NMDA) inhibits oxotremorine-induced acid secretion was examined in rat stomach, in relation to the cyclic GMP system. NMDA (10(-7) M) did not affect the spontaneous acid secretion from the everted preparations of isolated rat stomach, but inhibited the acid secretion stimulated by oxotremorine, and this effect of NMDA was antagonized by 2-amino-5-phosphonovaleric acid (AP-5), (+/-)3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid (CPP) or N(G)-nitro-L-arginine (L-NNA). NMDA also elevated the cyclic GMP content of mucosal slices from rat stomach, and this effect of NMDA was antagonized by L-NNA. These results indicate that NMDA receptors are present in the rat stomach and regulate the gastric acid secretion. The mechanism underlying the effect of NMDA inhibits oxotremorine-induced acid secretion may be mediated by the NO-dependent cyclic GMP system.

  16. A 16-year-old girl with anti-NMDA-receptor encephalitis and family history of psychotic disorders.

    PubMed

    Cleland, Neil; Lieblich, Samuel; Schalling, Martin; Rahm, Christoffer

    2015-12-01

    Autoimmune NMDA-R encephalitis (ANRE) shares clinical features with schizophrenia. Recent research also indicates that both disorders are associated with dysfunction of the N-Methyl-D-Aspartate glutamate receptors (NMDA-R) subunit 1. We present the case of Ms A, 16 years old. Ms A presented with acute personality change, bizarre behaviour, delusional ideas and atypical seizures. She had a family history of psychotic disorders, and autistic traits diagnosed in childhood. She was initially diagnosed with a psychotic disorder. Delayed testing of CSF indicated ANRE. As the patient was a Jehovah's witness the treating team was unable to use gammaglobulin therapy; they instead relied on combined plasmapheresis and rituximab. To exclude the possibility that the affected members of this family shared a gene coding for an abnormal configuration of the NMDA receptor subunit 1 we sequenced the region of the GRIN1 gene in DNA extracted from blood in both Ms A and her grandmother. Ms A's condition improved dramatically, though her long-term memory is still demonstrably impaired. No genetic abnormality was detected. This case emphasizes how important it is, for a first episode psychosis, to exclude ANRE and other autoimmune synaptic encephalitides, even in the face of significant family history, and if seronegative, the importance of testing for CSF autoantibodies.

  17. Effects of metabotropic glutamate receptor block on the synaptic transmission and plasticity in the rat medial vestibular nuclei.

    PubMed

    Grassi, S; Malfagia, C; Pettorossi, V E

    1998-11-01

    In rat brainstem slices, we investigated the possible role of metabotropic glutamate receptors in modulating the synaptic transmission within the medial vestibular nuclei, under basal and plasticity inducing conditions. We analysed the effect of the metabotropic glutamate receptor antagonist (R,S)-alpha-methyl-4-carboxyphenylglycine on the amplitude of the field potentials and latency of unitary potentials evoked in the ventral portion of the medial vestibular nuclei by primary vestibular afferent stimulation, and on the induction and maintenance of long-term potentiation, after high-frequency stimulation. Two effects were observed, consisting of a slight increase of the field potentials and reduction of unit latency during the drug infusion, and a further long-lasting development of these modifications after the drug wash-out. The long-term effect depended on N-methyl-D-aspartate receptor activation, as D,L-2-amino-5-phosphonopentanoic acid prevented its development. We suggest that (R,S)-alpha-methyl-4carboxyphenylglycine enhances the vestibular responses and induces N-methyl-D-aspartate-dependent long-term potentiation by increasing glutamate release, through the block of presynaptic metabotropic glutamate receptors which actively inhibit it. The block of these receptors was indirectly supported by the fact that the agonist (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid reduced the vestibular responses and blocked the induction of long-term potentiation by high-frequency stimulation. The simultaneous block of metabotropic glutamate receptors facilitating synaptic plasticity, impedes the full expression of the long-term effect throughout the (R,S)-alpha-methyl-4-carboxyphenylglycine infusion. The involvement of such a facilitatory mechanism in the potentiation is supported by its reversible reduction following a second (R,S)-alpha-methyl-4-carboxyphenylglycine infusion. The drug also reduced the expression of potentiation induced by high-frequency stimulation

  18. The effect of neonatal N-methyl-D-aspartate receptor blockade on exploratory and anxiety-like behaviors in adult BALB/c and C57BL/6 mice.

    PubMed

    Akillioglu, Kubra; Binokay, Secil; Kocahan, Sayad

    2012-07-15

    N-methyl-D-aspartate (NMDA) receptors play an important role in brain maturation and developmental processes. In our study, we evaluated the effects of neonatal NMDA receptor blockade on exploratory locomotion and anxiety-like behaviors of adult BALB/c and C57BL/6 mice. In this study, NMDA receptor hypofunction was induced 7-10 days after birth using MK-801 in BALB/c and C57BL/6 mice (0.25mg/kg twice a day for 4 days via intraperitoneal injection). The open-field (OF) and elevated plus maze (EPM) tests were used to evaluate exploratory locomotion and anxiety-like behaviors. In the OF, BALB/c mice spent less time in the center of the field (p<0.05) and had less vertical locomotor activity (p<0.01) compared to C57BL/6 mice. In BALB/c mice, MK-801 caused a decrease in vertical and horizontal locomotor activity in the OF test, compared to the control group (p<0.05). In C57BL/6 mice, MK-801 treatment increased horizontal locomotor activity and decreased time spent in the center in the OF test (p<0.05). In the EPM, the number of open-arm entries, the percentage of open-arm time (p<0.01) and total arm entries (p<0.05) were lower in BALB/c mice compared to C57BL/6 mice. In BALB/c mice, MK-801 caused an increase in the percentage of open-arm time compared to the control group (p<0.05). In C57BL/6 mice, MK-801 caused a decrease in the percentage of open-arm time compared to the control group (p<0.05). MK-801 decreased exploratory and anxiety-like behaviors in BALB/c mice. In contrast, MK-801 increased exploratory and anxiety-like behaviors in C57BL/6 mice. In conclusion, hereditary factors may play an important role in neonatal NMDA receptor blockade-induced responses. Copyright © 2012 Elsevier B.V. All rights reserved.

  19. Synthesis and receptor binding studies of (+/-)1-iodo-MK-801

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yang, D.J.; Ciliax, B.J.; Van Dort, M.E.

    1989-06-01

    The glutamate analogue N-methyl-D-aspartate (NMDA) binds to a subset of glutamate receptors that are coupled to a voltage-sensitive cation channel. This NMDA-linked channel is the likely binding locus of the potent anticonvulsant MK-801. To develop single-photon emission computed tomography (SPECT) probes of this brain channel, we synthesized (+/)1-iodo-MK-801 and (+/-)1-({sup 125}I)iodo-MK-801. The effect of (+/-)1-iodo-MK-801 on ligand binding to the NMDA-linked glutamate receptor site was assessed using a rat brain homogenate assay. (+/-)1-Iodo-MK-801 displaced the dissociative anesthetic ligand ({sup 3}H)N-(1-(2-thienyl)cyclohexyl)piperidine (({sup 3}H)TCP) binding with an IC50 of 1 microM, which is a 10-fold lower binding affinity than that of (+/-)MK-801.more » In in vivo autoradiographic studies, (+/-)MK-801 failed to block selective uptake of (+/-)1-iodo-MK-801 in rat brain. These results suggest that (+/-)1-iodo-MK-801 may not be a suitable ligand for mapping NMDA-linked glutamate receptor channels.« less

  20. Tryptophanol-derived oxazolopiperidone lactams: identification of a hit compound as NMDA receptor antagonist.

    PubMed

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

    2014-08-01

    N-Methyl-D-aspartate receptors (NMDAR) exacerbated activation leads to neuron death through a phenomenon called excitotoxicity. These receptors are implicated in several neurological diseases (e.g., Alzheimer and Parkinson) and thus represent an important therapeutic target. We herein describe the study of enantiopure tryptophanol-derived oxazolopiperidone lactams as NMDA receptor antagonists. The most active hit exhibited an IC50 of 63.4 μM in cultured rat cerebellar granule neurons thus being 1.5 fold more active than clinically approved NMDA antagonist amantadine (IC50=92 μM). Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. The effects of verapamil and its combinations with glutamate and glycine on cardiodynamics, coronary flow and oxidative stress in isolated rat heart.

    PubMed

    Stojic, Isidora; Srejovic, Ivan; Zivkovic, Vladimir; Jeremic, Nevena; Djuric, Marko; Stevanovic, Ana; Milanovic, Tamara; Djuric, Dragan; Jakovljevic, Vladimir

    2017-02-01

    The role of N-methyl-D-aspartate receptor (NMDA-R) in heart is still unclear. For these ionotropic glutamate receptors is characteristic the necessity of both co-agonists, glutamate and glycine, for their activation, which primarily allows influx of calcium. The aim of the present study was to examine the effects of verapamil, as a calcium channel blocker, alone and its combination with glycine and/or glutamate on cardiac function, coronary flow, and oxidative stress in isolated rat heart or to examine the effects of potential activation of NMDA-R in isolated rat heart. The hearts of male Wistar albino rats were excised and perfused according to Langendorff technique, and cardiodynamic parameters and coronary flow were determined during the administration of verapamil and its combinations with glutamate and/or glycine. The oxidative stress biomarkers, including thiobarbituric acid-reactive substances, nitrites, superoxide anion radical, and hydrogen peroxide, were each determined spectrophotometrically from coronary venous effluent. The greatest decline in parameters of cardiac contractility and systolic pressure was in the group that was treated with verapamil only, while minimal changes were observed in group treated with all three tested substances. Also, the largest changes in coronary flow were in the group treated only with verapamil, and at least in the group that received all three tested substances, as well as the largest increase in oxidative stress parameters. Based on the obtained results, it can be concluded that NMDA-R activation allows sufficient influx of calcium to increase myocardial contractility and systolic pressure, as well as short-term increase of oxidative stress.

  2. NMDA-Type Glutamate Receptor Activation Promotes Vascular Remodeling and Pulmonary Arterial Hypertension.

    PubMed

    Dumas, Sébastien J; Bru-Mercier, Gilles; Courboulin, Audrey; Quatredeniers, Marceau; Rücker-Martin, Catherine; Antigny, Fabrice; Nakhleh, Morad K; Ranchoux, Benoit; Gouadon, Elodie; Vinhas, Maria-Candida; Vocelle, Matthieu; Raymond, Nicolas; Dorfmüller, Peter; Fadel, Elie; Perros, Frédéric; Humbert, Marc; Cohen-Kaminsky, Sylvia

    2018-05-29

    Excessive proliferation and apoptosis resistance in pulmonary vascular cells underlie vascular remodeling in pulmonary arterial hypertension (PAH). Specific treatments for PAH exist, mostly targeting endothelial dysfunction, but high pulmonary arterial pressure still causes heart failure and death. Pulmonary vascular remodeling may be driven by metabolic reprogramming of vascular cells to increase glutaminolysis and glutamate production. The N -methyl-d-aspartate receptor (NMDAR), a major neuronal glutamate receptor, is also expressed on vascular cells, but its role in PAH is unknown. We assessed the status of the glutamate-NMDAR axis in the pulmonary arteries of patients with PAH and controls through mass spectrometry imaging, Western blotting, and immunohistochemistry. We measured the glutamate release from cultured pulmonary vascular cells using enzymatic assays and analyzed NMDAR regulation/phosphorylation through Western blot experiments. The effect of NMDAR blockade on human pulmonary arterial smooth muscle cell proliferation was determined using a BrdU incorporation assay. We assessed the role of NMDARs in vascular remodeling associated to pulmonary hypertension, in both smooth muscle-specific NMDAR knockout mice exposed to chronic hypoxia and the monocrotaline rat model of pulmonary hypertension using NMDAR blockers. We report glutamate accumulation, upregulation of the NMDAR, and NMDAR engagement reflected by increases in GluN1-subunit phosphorylation in the pulmonary arteries of human patients with PAH. K v channel inhibition and type A-selective endothelin receptor activation amplified calcium-dependent glutamate release from human pulmonary arterial smooth muscle cell, and type A-selective endothelin receptor and platelet-derived growth factor receptor activation led to NMDAR engagement, highlighting crosstalk between the glutamate-NMDAR axis and major PAH-associated pathways. The platelet-derived growth factor-BB-induced proliferation of human

  3. Septohippocampal GABAergic neurons mediate the altered behaviors induced by n-methyl-D-aspartate receptor antagonists.

    PubMed

    Ma, Jingyi; Tai, Siew Kian; Leung, L Stan

    2012-12-01

    We hypothesize that selective lesion of the septohippocampal GABAergic neurons suppresses the altered behaviors induced by an N-methyl-D-aspartate (NMDA) receptor antagonist, ketamine or MK-801. In addition, we hypothesize that septohippocampal GABAergic neurons generate an atropine-resistant theta rhythm that coexists with an atropine-sensitive theta rhythm in the hippocampus. Infusion of orexin-saporin (ore-SAP) into the medial septal area decreased parvalbumin-immunoreactive (GABAergic) neurons by ~80%, without significantly affecting choline-acetyltransferase-immunoreactive (cholinergic) neurons. The theta rhythm during walking, or the immobility-associated theta induced by pilocarpine, was not different between ore-SAP and sham-lesion rats. Walking theta was, however, more disrupted by atropine sulfate in ore-SAP than in sham-lesion rats. MK-801 (0.5 mg/kg i.p.) induced hyperlocomotion associated with an increase in frequency, but not power, of the hippocampal theta in both ore-SAP and sham-lesion rats. However, MK-801 induced an increase in 71-100 Hz gamma waves in sham-lesion but not ore-SAP lesion rats. In sham-lesion rats, MK-801 induced an increase in locomotion and an impairment of prepulse inhibition (PPI), and ketamine (3 mg/kg s.c.) induced a loss of gating of hippocampal auditory evoked potentials. MK-801-induced behavioral hyperlocomotion and PPI impairment, and ketamine-induced auditory gating deficit were reduced in ore-SAP rats as compared to sham-lesion rats. During baseline without drugs, locomotion and auditory gating were not different between ore-SAP and sham-lesion rats, and PPI was slightly but significantly increased in ore-SAP as compared with sham lesion rats. It is concluded that septohippocampal GABAergic neurons are important for the expression of hyperactive and psychotic symptoms an enhanced hippocampal gamma activity induced by ketamine and MK-801, and for generating an atropine-resistant theta. Selective suppression of

  4. On the mechanism of aluminum ion-induced neurotoxicity: The effects of aluminum species on G-protein-mediated processes and on drug interactions with the N-methyl-D-aspartate modulated ionophore

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hubbard, C.M.

    1989-01-01

    To establish what effects Al{sup 3+} may have on G-protein mediate signal transduction, the effects of Al{sup 3+} on the signal-coupling G-protein from retinal rod outer segments (G{sub t} or transducin) have been investigated as a model for the effects of Al{sup 3+} on signal transduction by G-proteins in general. In this investigation, we have studied the effects of Al{sup 3+} on the isolated, light-dependent rhodopsin catalyzed GTP-GDP exchange on G{sub t}; the light-dependent GTPase activity of G{sub t}; the light-independent cGMP hydrolysis by PDE; and the light activated, rhodopsin catalyzed, cGMP hydrolysis by PDE in vitro. To determine themore » effects of two defined species of aluminum on N-methyl-D-aspartic acid (NMDA) receptor-channel modulation we utilized a specific radioligand binding assay. This allowed us to compare the effects of aluminum to other metal ions on specific ({sup 3}H)MK-801 binding to the NMDA receptor-channel complex. This complex is involved in long-term potentiation, which is currently being investigated as the mechanism by which learning and memory occur and has been implicated in the pathology of Alzheimer's disease. We have investigated the effects of two different species of aluminum, as well as Ca{sup 2+}, Zn{sup 2+}, Mg{sup 2+}, and Li{sup +} on the specific binding of ({sup 3}H)MK-801 to the NMDA receptor-channel complex under depolarized conditions.« less

  5. The utility of ionotropic glutamate receptor antagonists in the treatment of nociception induced by epidural glutamate infusion in rats.

    PubMed

    Osgood, Doreen B; Harrington, William F; Kenney, Elizabeth V; Harrington, J Frederick

    2013-01-01

    The authors have previously demonstrated that human herniated disc material contains high concentrations of free glutamate. In an experimental model, elevated epidural glutamate concentrations in the lumbar spine can cause a focal hyperesthetic state. Rats underwent epidural glutamate infusion in the lumbar spine by a miniosmotic pump over a 72-hour period. Some rats underwent coinfusion with glutamate and ionotropic glutamate antagonists. Nociception was assessed by von Frey fibers and by assessment of glutamate receptor expression in the corresponding dorsal horn of the spinal cord. The kainic acid antagonist, UBP 301, decreased epidural glutamate-based hyperesthesia in a dose dependent manner. Concordant with these findings, there was significant decrease in kainate receptor expression in the dorsal horn. The N-Methyl-4-isoxazoleproionic acid (NMDA) antagonist Norketamine also significantly diminished hyperesthesia and decreased receptor expression in the dorsal horn. Both UBP 301, the kainic acid receptor antagonist and Norketamine, an NMDA receptor antagonist, dampened epidural glutamate-based nociception. Focal epidural injections of Kainate or NMDA receptor antagonists could be effective treatments for disc herniation-based lumbar radiculopathy.

  6. CDKL5 controls postsynaptic localization of GluN2B-containing NMDA receptors in the hippocampus and regulates seizure susceptibility.

    PubMed

    Okuda, Kosuke; Kobayashi, Shizuka; Fukaya, Masahiro; Watanabe, Aya; Murakami, Takuto; Hagiwara, Mai; Sato, Tempei; Ueno, Hiroe; Ogonuki, Narumi; Komano-Inoue, Sayaka; Manabe, Hiroyuki; Yamaguchi, Masahiro; Ogura, Atsuo; Asahara, Hiroshi; Sakagami, Hiroyuki; Mizuguchi, Masashi; Manabe, Toshiya; Tanaka, Teruyuki

    2017-10-01

    Mutations in the Cyclin-dependent kinase-like 5 (CDKL5) gene cause severe neurodevelopmental disorders accompanied by intractable epilepsies, i.e. West syndrome or atypical Rett syndrome. Here we report generation of the Cdkl5 knockout mouse and show that CDKL5 controls postsynaptic localization of GluN2B-containing N-methyl-d-aspartate (NMDA) receptors in the hippocampus and regulates seizure susceptibility. Cdkl5 -/Y mice showed normal sensitivity to kainic acid; however, they displayed significant hyperexcitability to NMDA. In concordance with this result, electrophysiological analysis in the hippocampal CA1 region disclosed an increased ratio of NMDA/α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor-mediated excitatory postsynaptic currents (EPSCs) and a significantly larger decay time constant of NMDA receptor-mediated EPSCs (NMDA-EPSCs) as well as a stronger inhibition of the NMDA-EPSCs by the GluN2B-selective antagonist ifenprodil in Cdkl5 -/Y mice. Subcellular fractionation of the hippocampus from Cdkl5 -/Y mice revealed a significant increase of GluN2B and SAP102 in the PSD (postsynaptic density)-1T fraction, without changes in the S1 (post-nuclear) fraction or mRNA transcripts, indicating an intracellular distribution shift of these proteins to the PSD. Immunoelectron microscopic analysis of the hippocampal CA1 region further confirmed postsynaptic overaccumulation of GluN2B and SAP102 in Cdkl5 -/Y mice. Furthermore, ifenprodil abrogated the NMDA-induced hyperexcitability in Cdkl5 -/Y mice, suggesting that upregulation of GluN2B accounts for the enhanced seizure susceptibility. These data indicate that CDKL5 plays an important role in controlling postsynaptic localization of the GluN2B-SAP102 complex in the hippocampus and thereby regulates seizure susceptibility, and that aberrant NMDA receptor-mediated synaptic transmission underlies the pathological mechanisms of the CDKL5 loss-of-function. Copyright © 2017 Elsevier Inc. All rights

  7. Epileptiform activity induced by lowering extracellular [Mg2+] in combined hippocampal-entorhinal cortex slices: modulation by receptors for norepinephrine and N-methyl-D-aspartate.

    PubMed

    Stanton, P K; Jones, R S; Mody, I; Heinemann, U

    1987-01-01

    Reduction of extracellular Mg2+ concentration induced spontaneous and evoked epileptiform activity in the entorhinal cortex (EC) and dentate gyrus (DG) of combined hippocampus (HC)-EC slices. Extracellular field potentials, as well as changes in extracellular Ca2+ and K+ concentrations, were measured in EC and DG with ion-selective/reference electrodes during both repetitive and single stimuli. In the EC, lowering extracellular [Mg2+] induces both spontaneous and single stimulus evoked ictal events consisting of extracellular negative potential shifts (up to 5 mV, 30 sec), decreases in [Ca2+]0 and increases in [K+]0. In the DG, spontaneous events were much shorter, but similar changes in [Ca2+]0, [K+]0 and field potentials (FPs) could be evoked by brief high-frequency stimulation. In both areas, the N-methyl-D-aspartate (NMDA) receptor antagonist 2-aminophosphonovalerate (2-APV) completely blocked spontaneous as well as stimulus evoked epileptiform events. The neurotransmitter norepinephrine (NE), which has previously been shown to modulate long-term potentiation in the DG, was found to exhibit differential modulation of epileptiform activity in the EC and DG. In the EC, NE, acting via alpha 1-receptors, completely blocked low Mg2+-induced epileptiform activity. In contrast, in the DG, NE exhibited a beta-receptor mediated prolongation of the low Mg2+-induced ictal events, and enhanced the stimulus-induced ionic and field potential changes. From these results, we conclude that lowering extracellular [Mg2+], acting in large part through the removal of the Mg2+ voltage-dependent blockade of NMDA receptors, leads to induction of epileptiform activity in both the EC and DG.(ABSTRACT TRUNCATED AT 250 WORDS)

  8. The uncompetitive N-methyl-D-aspartate antagonist memantine reduces binge-like eating, food-seeking behavior, and compulsive eating: role of the nucleus accumbens shell.

    PubMed

    Smith, Karen L; Rao, Rahul R; Velázquez-Sánchez, Clara; Valenza, Marta; Giuliano, Chiara; Everitt, Barry J; Sabino, Valentina; Cottone, Pietro

    2015-03-13

    Binge-eating disorder is characterized by excessive, uncontrollable consumption of palatable food within brief periods of time. The role of the glutamatergic N-methyl-D-aspartate (NMDA) receptor system in hedonic feeding is poorly understood. The aim of this study was to characterize the effects of the uncompetitive NMDA receptor antagonist memantine on palatable food-induced behavioral adaptations using a rat model, which mimics the characteristic symptomatology observed in binge-eating disorder. For this purpose, we allowed male Wistar rats to respond to obtain a highly palatable, sugary diet (Palatable group) or a regular chow diet (Chow control group), for 1 h a day, under a fixed-ratio 1 (FR1) schedule of reinforcement. Upon stabilization of food responding, we tested the effects of memantine on the Chow and Palatable food groups' intake. Then, we tested the effects of memantine on food-seeking behavior, under a second-order schedule of reinforcement. Furthermore, we investigated the effects of memantine on the intake of food when it was offered in an aversive, bright compartment of a light/dark conflict test. Finally, we evaluated the effects of memantine on FR1 responding for food, when microinfused into the nucleus accumbens (NAcc) shell or core. Memantine dose-dependently decreased binge-like eating and fully blocked food-seeking behavior and compulsive eating, selectively in the Palatable food group. The drug treatment did not affect performance of the control Chow food group. Finally, intra-NAcc shell, but not core, microinfusion of memantine decreased binge-like eating. Together, these findings substantiate a role of memantine as a potential pharmacological treatment for binge-eating disorder.

  9. The Uncompetitive N-methyl-D-Aspartate Antagonist Memantine Reduces Binge-Like Eating, Food-Seeking Behavior, and Compulsive Eating: Role of the Nucleus Accumbens Shell

    PubMed Central

    Smith, Karen L; Rao, Rahul R; Velázquez-Sánchez, Clara; Valenza, Marta; Giuliano, Chiara; Everitt, Barry J; Sabino, Valentina; Cottone, Pietro

    2015-01-01

    Binge-eating disorder is characterized by excessive, uncontrollable consumption of palatable food within brief periods of time. The role of the glutamatergic N-methyl-D-aspartate (NMDA) receptor system in hedonic feeding is poorly understood. The aim of this study was to characterize the effects of the uncompetitive NMDA receptor antagonist memantine on palatable food-induced behavioral adaptations using a rat model, which mimics the characteristic symptomatology observed in binge-eating disorder. For this purpose, we allowed male Wistar rats to respond to obtain a highly palatable, sugary diet (Palatable group) or a regular chow diet (Chow control group), for 1 h a day, under a fixed-ratio 1 (FR1) schedule of reinforcement. Upon stabilization of food responding, we tested the effects of memantine on the Chow and Palatable food groups' intake. Then, we tested the effects of memantine on food-seeking behavior, under a second-order schedule of reinforcement. Furthermore, we investigated the effects of memantine on the intake of food when it was offered in an aversive, bright compartment of a light/dark conflict test. Finally, we evaluated the effects of memantine on FR1 responding for food, when microinfused into the nucleus accumbens (NAcc) shell or core. Memantine dose-dependently decreased binge-like eating and fully blocked food-seeking behavior and compulsive eating, selectively in the Palatable food group. The drug treatment did not affect performance of the control Chow food group. Finally, intra-NAcc shell, but not core, microinfusion of memantine decreased binge-like eating. Together, these findings substantiate a role of memantine as a potential pharmacological treatment for binge-eating disorder. PMID:25381776

  10. Neurosteroid-like Inhibitors of N-Methyl-d-aspartate Receptor: Substituted 2-Sulfates and 2-Hemisuccinates of Perhydrophenanthrene.

    PubMed

    Slavikova, Barbora; Chodounska, Hana; Nekardova, Michaela; Vyklicky, Vojtech; Ladislav, Marek; Hubalkova, Pavla; Krausova, Barbora; Vyklicky, Ladislav; Kudova, Eva

    2016-05-26

    N-Methyl-d-aspartate receptors (NMDARs) display a critical role in various diseases of the central nervous system. The activity of NMDARs can be modulated by neurosteroids. Herein, we report a structure-activity relationship study for perhydrophenanthrene analogues possessing a framework that mimics the steroidal ring system. This study comprises the design, synthesis, and assessment of the biological activity of a library of perhydrophenanthrene 2-sulfates and 2-hemisuccinates (1-10). Their ability to modulate NMDAR-induced currents was tested on recombinant GluN1/GluN2B receptors. Our results demonstrate that such structural optimization leads to compounds that are inhibitors of NMDARs. Notably, compound 9 (IC50 = 15.6 μM) was assessed as a more potent inhibitor of NMDAR-induced currents than the known endogenous neurosteroid, pregnanolone sulfate (IC50 = 24.6 μM).

  11. Influence of Pharmacological Manipulations of NMDA and Cholinergic Receptors on Working versus Reference Memory in a Dual Component Odor Span Task

    ERIC Educational Resources Information Center

    MacQueen, David A.; Dalrymple, Savannah R.; Drobes, David J.; Diamond, David M.

    2016-01-01

    Developed as a tool to assess working memory capacity in rodents, the odor span task (OST) has significant potential to advance drug discovery in animal models of psychiatric disorders. Prior investigations indicate OST performance is impaired by systemic administration of N-methyl-D-aspartate receptor (NMDA-r) antagonists and is sensitive to…

  12. High sensitivity and specificity in proposed clinical diagnostic criteria for anti-N-methyl-D-aspartate receptor encephalitis.

    PubMed

    Ho, Alvin C C; Mohammad, Shekeeb S; Pillai, Sekhar C; Tantsis, Esther; Jones, Hannah; Ho, Reena; Lim, Ming; Hacohen, Yael; Vincent, Angela; Dale, Russell C

    2017-12-01

    To determine the validity of the proposed clinical diagnostic criteria for anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis in paediatric patients. The diagnostic criteria for anti-NMDAR encephalitis proposed by Graus et al. (2016) use clinical features and conventional investigations to facilitate early immunotherapy before antibody status is available. The criteria are satisfied if patients develop four out of six symptom groups within 3 months, together with at least one abnormal investigation (electroencephalography/cerebrospinal fluid) and reasonable exclusion of other disorders. We evaluated the validity of the criteria using a retrospective cohort of paediatric patients with encephalitis. Twenty-nine patients with anti-NMDAR encephalitis and 74 comparison children with encephalitis were included. As expected, the percentage of patients with anti-NMDAR encephalitis who fulfilled the clinical criteria increased over time. During the hospital inpatient admission, most patients (26/29, 90%) with anti-NMDAR encephalitis fulfilled the criteria, significantly more than the comparison group (3/74, 4%) (p<0.001). The median time of fulfilling the criteria in patients with anti-NMDAR encephalitis was 2 weeks from first symptom onset (range 1-6). The sensitivity of the criteria was 90% (95% confidence interval 73-98) and the specificity was 96% (95% confidence interval 89-99). The proposed diagnostic criteria for anti-NMDAR encephalitis have good sensitivity and specificity. Incomplete criteria do not exclude the diagnosis. The proposed clinical diagnostic criteria for anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis by Graus et al. (2016) have high sensitivity and specificity in paediatric patients. The median time of fulfilling the criteria in patients with anti-NMDAR was 2 weeks from first symptom onset. © 2017 Mac Keith Press.

  13. 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

  14. Central phencyclidine (PCP) receptor binding is glutamate dependent: evidence for a PCP/excitatory amino acid receptor (EAAR) complex

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Loo, P.; Braunwalder, A.; Lehmann, J.

    PCP and other dissociative anesthetica block the increase in neuronal firing rate evoked by the EAAR agonist, N-methyl-Daspartate. NMDA and other EAAs such as glutamate (glu) have not been previously shown to affect PCP ligand binding. In the present study, using once washed rat forebrain membranes, 10 ..mu..M-glu was found to increase the binding of (/sup 3/H)TCP, a PCP analog, to defined PCP recognition sites by 20%. Removal of glu and aspartate (asp) by extensive washing decreased TCP binding by 75-90%. In these membranes, 10 ..mu..M L-glu increased TCP binding 3-fold. This effect was stereospecific and evoked by other EAAsmore » with the order of activity, L-glu > D-asp > L- asp > NMDA > D-glu > quisqualate. Kainate, GABA, NE, DA, 5-HT, 2-chloroadenosine, oxotremorine and histamine had no effect on TCP binding at concentrations up to 100 ..mu..M. The effects of L-glu were attenuated by the NMDA-type receptor antagonist, 2-amino-7--phosphonoheptanoate (AP7; 10 ..mu..M-1 mM). These findings indicate that EAAS facilitate TCP binding, possibly through NMDA-type receptors. The observed interaction between the PCP receptor and EAARs may reflect the existence of a macromolecular receptor complex similar to that demonstrated for the benzodiazepines and GABA.« less

  15. Pregnanolone Glutamate, a Novel Use-Dependent NMDA Receptor Inhibitor, Exerts Antidepressant-Like Properties in Animal Models.

    PubMed

    Holubova, Kristina; Nekovarova, Tereza; Pistovcakova, Jana; Sulcova, Alexandra; Stuchlík, Ales; Vales, Karel

    2014-01-01

    A number of studies demonstrated a rapid onset of an antidepressant effect of non-competitive N-methyl-d-aspartic acid receptor (NMDAR) antagonists. Nonetheless, its therapeutic potential is rather limited, due to a high coincidence of negative side-effects. Therefore, the challenge seems to be in the development of NMDAR antagonists displaying antidepressant properties, and at the same time maintaining regular physiological function of the NMDAR. Previous results demonstrated that naturally occurring neurosteroid 3α5β-pregnanolone sulfate shows pronounced inhibitory action by a use-dependent mechanism on the tonically active NMDAR. The aim of the present experiments is to find out whether the treatment with pregnanolone 3αC derivatives affects behavioral response to chronic and acute stress in an animal model of depression. Adult male mice were used throughout the study. Repeated social defeat and forced swimming tests were used as animal models of depression. The effect of the drugs on the locomotor/exploratory activity in the open-field test was also tested together with an effect on anxiety in the elevated plus maze. Results showed that pregnanolone glutamate (PG) did not induce hyperlocomotion, whereas both dizocilpine and ketamine significantly increased spontaneous locomotor activity in the open field. In the elevated plus maze, PG displayed anxiolytic-like properties. In forced swimming, PG prolonged time to the first floating. Acute treatment of PG disinhibited suppressed locomotor activity in the repeatedly defeated group-housed mice. Aggressive behavior of isolated mice was reduced after the chronic 30-day administration of PG. PG showed antidepressant-like and anxiolytic-like properties in the used tests, with minimal side-effects. Since PG combines GABAA receptor potentiation and use-dependent NMDAR inhibition, synthetic derivatives of neuroactive steroids present a promising strategy for the treatment of mood disorders. -3α5

  16. Glutamate Increases In Vitro Survival and Proliferation and Attenuates Oxidative Stress-Induced Cell Death in Adult Spinal Cord-Derived Neural Stem/Progenitor Cells via Non-NMDA Ionotropic Glutamate Receptors.

    PubMed

    Hachem, Laureen D; Mothe, Andrea J; Tator, Charles H

    2016-08-15

    Traumatic spinal cord injury (SCI) leads to a cascade of secondary chemical insults, including oxidative stress and glutamate excitotoxicity, which damage host neurons and glia. Transplantation of exogenous neural stem/progenitor cells (NSPCs) has shown promise in enhancing regeneration after SCI, although survival of transplanted cells remains poor. Understanding the response of NSPCs to the chemical mediators of secondary injury is essential in finding therapies to enhance survival. We examined the in vitro effects of glutamate and glutamate receptor agonists on adult rat spinal cord-derived NSPCs. NSPCs isolated from the periventricular region of the adult rat spinal cord were exposed to various concentrations of glutamate for 96 h. We found that glutamate treatment (500 μM) for 96 h significantly increased live cell numbers, reduced cell death, and increased proliferation, but did not significantly alter cell phenotype. Concurrent glutamate treatment (500 μM) in the setting of H2O2 exposure (500 μM) for 10 h increased NSPC survival compared to H2O2 exposure alone. The effects of glutamate on NSPCs were blocked by the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)/kainate receptor antagonist GYKI-52466, but not by the N-methyl-D-aspartic acid receptor antagonist MK-801 or DL-AP5, or the mGluR3 antagonist LY-341495. Furthermore, treatment of NSPCs with AMPA, kainic acid, or the kainate receptor-specific agonist (RS)-2-amino-3-(3-hydroxy-5-tert-butylisoxazol-4-yl)propanoic acid mimicked the responses seen with glutamate both alone and in the setting of oxidative stress. These findings offer important insights into potential mechanisms to enhance NSPC survival and implicate a potential role for glutamate in promoting NSPC survival and proliferation after traumatic SCI.

  17. Molecular basis for subtype-specificity and high-affinity zinc inhibition in the GluN1-GluN2A NMDA receptor amino terminal domain

    PubMed Central

    Romero-Hernandez, Annabel; Simorowski, Noriko; Karakas, Erkan

    2016-01-01

    Summary Zinc is vastly present in the mammalian brain and controls functions of various cell surface receptors to regulate neurotransmission. A distinctive characteristic of N-methyl-D-aspartate (NMDA) receptors containing a GluN2A subunit is that their ion channel activity is allosterically inhibited by a nano-molar concentration of zinc that binds to an extracellular domain called an amino terminal domain (ATD). Despite physiological importance, the molecular mechanism underlying the high-affinity zinc inhibition has been incomplete due to lack of a GluN2A ATD structure. Here we show the first crystal structures of the heterodimeric GluN1-GluN2A ATD, which provide the complete map of the high-affinity zinc binding site and reveals distinctive features from the ATD of the GluN1-GluN2B subtype. Perturbation of hydrogen bond networks at the hinge of the GluN2A bi-lobe structure affects both zinc inhibition and open probability supporting the general model where the bi-lobe motion in ATD regulates the channel activity in NMDA receptors. PMID:27916457

  18. Activation of the prelimbic medial prefrontal cortex induces anxiety-like behaviors via N-Methyl-D-aspartate receptor-mediated glutamatergic neurotransmission in mice.

    PubMed

    Saitoh, Akiyoshi; Ohashi, Masanori; Suzuki, Satoshi; Tsukagoshi, Mai; Sugiyama, Azusa; Yamada, Misa; Oka, Jun-Ichiro; Inagaki, Masatoshi; Yamada, Mitsuhiko

    2014-08-01

    We investigated the possible roles of the prelimbic medial prefrontal cortex (PL) in the regulation of anxiety-like behaviors by pharmacologically activating the terminals of neuronal inputs or postsynaptic efferent neurons with a sodium channel activator veratrine. The extracellular glutamate levels were measured by in vivo microdialysis, and the behaviors were assessed with the open field (OF) test in mice simultaneously. The samples were collected every 10 min for 60 min, as basal levels of glutamate. The medium containing drugs were perfused for 30 min. The OF test was performed in the last 10 min of drug perfusion. After the drug treatments, the perfusion medium containing drugs was switched back to perfusion medium without drugs, and then samples were collected for another 90 min. The extracellular glutamate levels were significantly elevated after local perfusion of veratrine in the PL. At the same time, perfusion of veratrine in the PL produced anxiety-like behaviors in mice. Local coperfusion of a sodium channel blocker, lamotrigine, completely diminished the veratrine-induced elevated extracellular glutamate levels and the behavioral changes. Local coperfusion of an NMDA receptor antagonist, MK-801, but not a non-NMDA (AMPA/kainate) receptor antagonist, CNQX, completely diminished the behavioral changes without any effects on the veratrine-induced elevated extracellular glutamate levels. This study demonstrates that the activation of the PL with veratrine induces anxiety-like behaviors via NMDA receptor-mediated glutamatergic neurotransmission in mice. © 2014 Wiley Periodicals, Inc.

  19. Motor impairments, striatal degeneration, and altered dopamine-glutamate interplay in mice lacking PSD-95.

    PubMed

    Zhang, Jingping; Saur, Taixiang; Duke, Angela N; Grant, Seth G N; Platt, Donna M; Rowlett, James K; Isacson, Ole; Yao, Wei-Dong

    2014-01-01

    Excessive activation of the N-methyl-d-aspartate (NMDA) receptor and the neurotransmitter dopamine (DA) mediate neurotoxicity and neurodegeneration under many neurological conditions, including Huntington's disease (HD), an autosomal dominant neurodegenerative disease characterized by the preferential loss of medium spiny projection neurons (MSNs) in the striatum. PSD-95 is a major scaffolding protein in the postsynaptic density (PSD) of dendritic spines, where a classical role for PSD-95 is to stabilize glutamate receptors at sites of synaptic transmission. Our recent studies indicate that PSD-95 also interacts with the D1 DA receptor localized in spines and negatively regulates spine D1 signaling. Moreover, PSD-95 forms ternary protein complexes with D1 and NMDA receptors, and plays a role in limiting the reciprocal potentiation between both receptors from being escalated. These studies suggest a neuroprotective role for PSD-95. Here we show that mice lacking PSD-95, resulting from genetic deletion of the GK domain of PSD-95 (PSD-95-ΔGK mice), sporadically develop progressive neurological impairments characterized by hypolocomotion, limb clasping, and loss of DARPP-32-positive MSNs. Electrophysiological experiments indicated that NMDA receptors in mutant MSNs were overactive, suggested by larger, NMDA receptor-mediated miniature excitatory postsynaptic currents (EPSCs) and higher ratios of NMDA- to AMPA-mediated corticostriatal synaptic transmission. In addition, NMDA receptor currents in mutant cortical neurons were more sensitive to potentiation by the D1 receptor agonist SKF81297. Finally, repeated administration of the psychostimulant cocaine at a dose regimen not producing overt toxicity-related phenotypes in normal mice reliably converted asymptomatic mutant mice to clasping symptomatic mice. These results support the hypothesis that deletion of PSD-95 in mutant mice produces concomitant overactivation of both D1 and NMDA receptors that makes neurons more

  20. Peripheral ionotropic glutamate receptors contribute to Fos expression increase in the spinal cord through antidromic electrical stimulation of sensory nerves.

    PubMed

    Li, Jia-Heng; He, Pei-Yao; Fan, Dan-Ni; Alemujiang, Dilinapa; Huo, Fu-Quan; Zhao, Yan; Cao, Dong-Yuan

    2018-06-21

    Previous studies have shown that peripheral ionotropic glutamate receptors are involved in the increase in sensitivity of a cutaneous branch of spinal dorsal ramus (CBDR) through antidromic electrical stimulation (ADES) of another CBDR in the adjacent segment. CBDR in the thoracic segments run parallel to each other and no synaptic contact at the periphery is reported. The present study investigated whether the increased sensitivity of peripheral sensory nerves via ADES of a CBDR induced Fos expression changes in the adjacent segments of the spinal cord. Fos expression increased in the T8 - T12 segments of the spinal cord evoked by ADES of the T10 CBDR in rats. The increased Fos expression in the T11 and T12, but not T8 - T10 spinal cord segments, was significantly blocked by local application of either N-methyl-D-aspartate (NMDA) receptor antagonist dizocilpine maleate (MK-801) or non-NMDA receptor antagonist 6,7-dinitroquinoxaline-2,3-dione (DNQX) into the receptive field of T11 CBDR. The results suggest that endogenous glutamate released by ADES of sensory nerve may bind to peripheral ionotropic glutamate receptors and activate adjacent sensory nerve endings to increase the sensitivity of the spinal cord. These data reveal the potential mechanisms of neuron activation in the spinal cord evoked by peripheral sensitization. Copyright © 2018 Elsevier B.V. All rights reserved.

  1. Anti-NMDA-receptor encephalitis presenting with catatonia and neuroleptic malignant syndrome in patients with intellectual disability and autism.

    PubMed

    Kiani, Reza; Lawden, Mark; Eames, Penelope; Critchley, Peter; Bhaumik, Sabyasachi; Odedra, Sunita; Gumber, Rohit

    2015-02-01

    We report anti-N-methyl-d-aspartate (NMDA) receptor encephalitis in two patients with autism and intellectual disability presenting with neuropsychiatric symptoms of catatonia and neuroleptic malignant syndrome. Case reports such as these help raise awareness of this clinical issue. By paving the way for earlier diagnoses they ultimately maximise the potential for curative treatments and prevention of long-term complications.

  2. Fractionating spatial memory with glutamate receptor subunit-knockout mice.

    PubMed

    Bannerman, David M

    2009-12-01

    In recent years, the contribution that different glutamate receptor subtypes and subunits make to spatial learning and memory has been studied extensively using genetically modified mice in which key proteins are knocked out. This has revealed dissociations between different aspects of spatial memory that were not previously apparent from lesion studies. For example, studies with GluA1 AMPAR [AMPA (alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid) receptor] subunit-knockout mice have revealed the presence of a GluA1-dependent, non-associative short-term memory mechanism that is important for performance on spatial working memory tasks, and a GluA1-independent, long-term associative memory mechanism which underlies performance on spatial reference memory tasks. Within this framework we have also studied the contributions of different GluN2-containing NMDARs [NMDA (N-methyl-D-aspartate) receptors] to spatial memory. Studies with GluN2 NMDAR mutants have revealed different contributions from GluN2A- and GluN2B-containing NMDARs to spatial learning. Furthermore, comparison of forebrain- and hippocampus-specific GluN2B-knockout mice has demonstrated that both hippocampal and extra-hippocampal NMDARs make important contributions to spatial memory performance.

  3. The role of NMDA receptors in human eating behavior: evidence from a case of anti-NMDA receptor encephalitis.

    PubMed

    Perogamvros, Lampros; Schnider, Armin; Leemann, Beatrice

    2012-06-01

    Research in animal models has implicated N-methyl-D-aspartate (NMDA) receptors (NMDARs) in the control of food intake. Until now, these findings have been not replicated in humans. Here we describe a 22-year-old woman with anti-NMDAR encephalitis and no prior neurological or psychiatric history. Her clinical course was marked by successive eating disorders: anorexia followed by hyperphagia. We propose that, much as they do in other animals, NMDARs in humans interact with the neuroendocrine, homeostatic, and reward systems controlling food intake in the central and peripheral nervous system structures related to feeding and satiety.

  4. D-serine signalling as a prominent determinant of neuronal-glial dialogue in the healthy and diseased brain.

    PubMed

    Billard, J-M

    2008-10-01

    Rather different from their initial image as passive supportive cells of the CNS, the astrocytes are now considered as active partners at synapses, able to release a set of gliotransmitter-like substances to modulate synaptic communication within neuronal networks. Whereas glutamate and ATP were first regarded as main determinants of gliotransmission, growing evidence indicates now that the amino acid D-serine is another important player in the neuronal-glial dialogue. Through the regulation of glutamatergic neurotransmission through both N-methyl-D-aspartate (NMDA-R) and non-NMDA-R, D-serine is helping in modelling the appropriate connections in the developing brain and influencing the functional plasticity within neuronal networks throughout lifespan. The understanding of D-serine signalling, which has increased linearly in the last few years, gives new insights into the critical role of impaired neuronal-glial communication in the diseased brain, and offers new opportunities for developing relevant strategies to treat cognitive deficits associated to brain disorders.

  5. D-serine signalling as a prominent determinant of neuronal-glial dialogue in the healthy and diseased brain

    PubMed Central

    Billard, J-M

    2008-01-01

    Rather different from their initial image as passive supportive cells of the CNS, the astrocytes are now considered as active partners at synapses, able to release a set of gliotransmitter-like substances to modulate synaptic communication within neuronal networks. Whereas glutamate and ATP were first regarded as main determinants of gliotransmission, growing evidence indicates now that the amino acid D-serine is another important player in the neuronal-glial dialogue. Through the regulation of glutamatergic neurotransmission through both N-methyl-D-aspartate (NMDA-R) and non-NMDA-R, D-serine is helping in modelling the appropriate connections in the developing brain and influencing the functional plasticity within neuronal networks throughout lifespan. The understanding of D-serine signalling, which has increased linearly in the last few years, gives new insights into the critical role of impaired neuronal-glial communication in the diseased brain, and offers new opportunities for developing relevant strategies to treat cognitive deficits associated to brain disorders. PMID:18363840

  6. Effects of NMDA receptor antagonists on probability discounting depend on the order of probability presentation.

    PubMed

    Yates, Justin R; Breitenstein, Kerry A; Gunkel, Benjamin T; Hughes, Mallory N; Johnson, Anthony B; Rogers, Katherine K; Shape, Sara M

    Risky decision making can be measured using a probability-discounting procedure, in which animals choose between a small, certain reinforcer and a large, uncertain reinforcer. Recent evidence has identified glutamate as a mediator of risky decision making, as blocking the N-methyl-d-aspartate (NMDA) receptor with MK-801 increases preference for a large, uncertain reinforcer. Because the order in which probabilities associated with the large reinforcer can modulate the effects of drugs on choice, the current study determined if NMDA receptor ligands alter probability discounting using ascending and descending schedules. Sixteen rats were trained in a probability-discounting procedure in which the odds against obtaining the large reinforcer increased (n=8) or decreased (n=8) across blocks of trials. Following behavioral training, rats received treatments of the NMDA receptor ligands MK-801 (uncompetitive antagonist; 0, 0.003, 0.01, or 0.03mg/kg), ketamine (uncompetitive antagonist; 0, 1.0, 5.0, or 10.0mg/kg), and ifenprodil (NR2B-selective non-competitive antagonist; 0, 1.0, 3.0, or 10.0mg/kg). Results showed discounting was steeper (indicating increased risk aversion) for rats on an ascending schedule relative to rats on the descending schedule. Furthermore, the effects of MK-801, ketamine, and ifenprodil on discounting were dependent on the schedule used. Specifically, the highest dose of each drug decreased risk taking in rats in the descending schedule, but only MK-801 (0.03mg/kg) increased risk taking in rats on an ascending schedule. These results show that probability presentation order modulates the effects of NMDA receptor ligands on risky decision making. Copyright © 2016 Elsevier Inc. All rights reserved.

  7. (+)-Pentazocine Reduces NMDA-Induced Murine Retinal Ganglion Cell Death Through a σR1-Dependent Mechanism

    PubMed Central

    Zhao, Jing; Mysona, Barbara A.; Qureshi, Azam; Kim, Lily; Fields, Taylor; Gonsalvez, Graydon B.; Smith, Sylvia B.; Bollinger, Kathryn E.

    2016-01-01

    Purpose To evaluate, in vivo, the effects of the sigma-1 receptor (σR1) agonist, (+)-pentazocine, on N-methyl-D-aspartate (NMDA)-mediated retinal excitotoxicity. Methods Intravitreal NMDA injections were performed in C57BL/6J mice (wild type [WT]) and σR1−/− (σR1 knockout [KO]) mice. Fellow eyes were injected with phosphate-buffered saline (PBS). An experimental cohort of WT and σR1 KO mice was administered (+)-pentazocine by intraperitoneal injection, and untreated animals served as controls. Retinas derived from mice were flat-mounted and labeled for retinal ganglion cells (RGCs). The number of RGCs was compared between NMDA and PBS-injected eyes for all groups. Apoptosis was assessed using TUNEL assay. Levels of extracellular-signal–regulated kinases (ERK1/2) were analyzed by Western blot. Results N-methyl-D-aspartate induced a significant increase in TUNEL-positive nuclei and a dose-dependent loss of RGCs. Mice deficient in σR1 showed greater RGC loss (≈80%) than WT animals (≈50%). (+)-Pentazocine treatment promoted neuronal survival, and this effect was prevented by deletion of σR1. (+)-Pentazocine treatment resulted in enhanced activation of ERK at the 6-hour time point following NMDA injection. The (+)-pentazocine–induced ERK activation was diminished in σR1 KO mice. Conclusions Targeting σR1 activation prevented RGC death while enhancing activation of the mitogen-activated protein kinase (MAPK), ERK1/2. Sigma-1 receptor is a promising therapeutic target for retinal neurodegenerative diseases. PMID:26868747

  8. Ethanol Inhibition of Recombinant NMDA Receptors Is Not Altered by Co-Expression of CaMKII-α or CaMKII-β

    PubMed Central

    Xu, Minfu; Chandler, L. Judson; Woodward, John J.

    2008-01-01

    Previous studies have shown that the N-methyl-D-aspartate (NMDA) receptor is an important target for the actions of ethanol in the brain. NMDA receptors are glutamate-activated ion channels that are highly expressed in neurons. They are activated during periods of significant glutamatergic synaptic activity and are an important source of the signaling molecule calcium in the post-synaptic spine. Alterations in the function of NMDA receptors by drugs or disease are associated with deficits in motor, sensory and cognitive processes of the brain. Acutely, ethanol inhibits ion flow through NMDA receptors while sustained exposure to ethanol can induce compensatory changes in the density and localization of the receptor. Defining factors that govern the acute ethanol sensitivity of NMDA receptors is an important step in how an individual responds to ethanol. In the present study, we investigated the effect of calcium-calmodulin dependent protein kinase II (CaMKII) on the ethanol sensitivity of recombinant NMDA receptors. CaMKII is a major constituent of the post-synaptic density and is critically involved in various forms of learning and memory. NMDA receptor subunits were transiently expressed in human embryonic kidney 293 cells (HEK 293) along with CaMKII-α or CaMKII-β tagged with the green fluorescent protein (GFP). Whole cell currents were elicited by brief exposures to glutamate and were measured using patchclamp electrophysiology. Neither CaMKII-α or CaMKII-β had any significant effect on the ethanol inhibition of NR1/2A or NR1/2B receptors. Ethanol inhibition was also unaltered by deletion of CaMKII binding domains in NR1 or NR2 subunits or by phospho-site mutants that mimic or occlude CaMKII phosphorylation. Chronic treatment of cortical neurons with ethanol had no significant effect on the expression of CaMKII-α or CaMKII-β. The results of this study suggest that CaMKII is not involved in regulating the acute ethanol sensitivity of NMDA receptors. PMID

  9. The interplay of BDNF-TrkB with NMDA receptor in propofol-induced cognition dysfunction : Mechanism for the effects of propofol on cognitive function.

    PubMed

    Zhou, Junfei; Wang, Fang; Zhang, Jun; Li, Jianfeng; Ma, Li; Dong, Tieli; Zhuang, Zhigang

    2018-04-05

    The aim of the present study was to verify whether propofol impaired learning and memory through the interplay of N-methyl-D-aspartate (NMDA) receptor with brain-derived neurotrophic factor (BDNF)-tyrosine kinase B (TrkB) signaling pathway. 120 Sprague-Dawley (SD) rats were randomly assigned into eight groups. Experimental drugs including saline, intralipid, propofol, N-methyl-D-aspartate (NMDA), 7,8-dihydroxyflavone (7,8-DHF), K252a and MK-801. Spatial learning and memory of rats were tested by the Morris water maze (MWM) test. The mRNA and protein expression were determined by immunohistochemistry, RT-PCR and western blot. Finally, hippocampus cells proliferation and apoptosis were examined by PCNA immunohistochemistry and TUNEL respectively. The memory and learning was diminished in the propofol exposure group, however, the impaired memory and learning of rats were improved with the addition of NMDA and 7,8-DHF, while the improvement of memory and learning of rats were reversed with the addition of K252a and MK-801. In addition, the mRNA and protein expression levels and hippocampus cells proliferation were the same trend with the results of the MWM test, while apoptosis in hippocampus was reversed. The propofol can impair memory and learning of rats and induce cognition dysfunction through the interplay of NMDA receptor and BDNF-TrkB-CREB signaling pathway.

  10. Increased accuracy of ligand sensing by receptor diffusion on cell surface

    NASA Astrophysics Data System (ADS)

    Aquino, Gerardo; Endres, Robert G.

    2010-10-01

    The physical limit with which a cell senses external ligand concentration corresponds to the perfect absorber, where all ligand particles are absorbed and overcounting of same ligand particles does not occur. Here, we analyze how the lateral diffusion of receptors on the cell membrane affects the accuracy of sensing ligand concentration. Specifically, we connect our modeling to neurotransmission in neural synapses where the diffusion of glutamate receptors is already known to refresh synaptic connections. We find that receptor diffusion indeed increases the accuracy of sensing for both the glutamate α -Amino-3-hydroxy-5-Methyl-4-isoxazolePropionic Acid (AMPA) and N -Methyl-D-aspartic Acid (NMDA) receptor, although the NMDA receptor is overall much noisier. We propose that the difference in accuracy of sensing of the two receptors can be linked to their different roles in neurotransmission. Specifically, the high accuracy in sensing glutamate is essential for the AMPA receptor to start membrane depolarization, while the NMDA receptor is believed to work in a second stage as a coincidence detector, involved in long-term potentiation and memory.

  11. Common influences of non-competitive NMDA receptor antagonists on the consolidation and reconsolidation of cocaine-cue memory.

    PubMed

    Alaghband, Yasaman; Marshall, John F

    2013-04-01

    Environmental stimuli or contexts previously associated with rewarding drugs contribute importantly to relapse among addicts, and research has focused on neurobiological processes maintaining those memories. Much research shows contributions of cell surface receptors and intracellular signaling pathways in maintaining associations between rewarding drugs (e.g., cocaine) and concurrent cues/contexts; these memories can be degraded at the time of their retrieval through reconsolidation interference. Much less studied is the consolidation of drug-cue memories during their acquisition. The present experiments use the cocaine-conditioned place preference (CPP) paradigm in rats to directly compare, in a consistent setting, the effects of N-methyl-D-aspartate (NMDA) glutamate receptor antagonists MK-801 and memantine on the consolidation and reconsolidation of cocaine-cue memories. For the consolidation studies, animals were systemically administered MK-801 or memantine immediately following training sessions. To investigate the effects of these NMDA receptor antagonists on the retention of previously established cocaine-cue memories, animals were systemically administered MK-801 or memantine immediately after memory retrieval. Animals given either NMDA receptor antagonist immediately following training sessions did not establish a preference for the cocaine-paired compartment. Post-retrieval administration of either NMDA receptor antagonist attenuated the animals' preference for the cocaine-paired compartment. Furthermore, animals given NMDA receptor antagonists post-retrieval showed a blunted response to cocaine-primed reinstatement. Using two distinct NMDA receptor antagonists in a common setting, these findings demonstrate that NMDA receptor-dependent processes contribute both to the consolidation and reconsolidation of cocaine-cue memories, and they point to the potential utility of treatments that interfere with drug-cue memory reconsolidation.

  12. MK-801-Treated Oligodendrocytes as a Cellular Model to Study Schizophrenia.

    PubMed

    Brandão-Teles, Caroline; Martins-de-Souza, Daniel; Guest, Paul C; Cassoli, Juliana S

    2017-01-01

    Glutamate is the most important excitatory neurotransmitter in the brain. The N-methyl-D-aspartate (NMDA) subtype of glutamate receptor is found both in neurons and glial cells such as oligodendrocytes, which have been shown to be dysfunctional in schizophrenia. For this reasons, the oligodendrocyte MO3.13 cell line has been used to study glutamatergic dysfunction as a model of schizophrenia using the NMDA receptor antagonists such as MK-801 to block receptor function. Here, we describe a comprehensive protocol for culturing and carrying out proteomic analyses of MK-801-treated MO3.13 cells as a means of identifying potential new biomarkers and targets for drug discovery in schizophrenia research.

  13. Schizophrenia patients show task switching deficits consistent with N-methyl-d-aspartate system dysfunction but not global executive deficits: implications for pathophysiology of executive dysfunction in schizophrenia.

    PubMed

    Wylie, Glenn R; Clark, E A; Butler, P D; Javitt, D C

    2010-05-01

    Schizophrenia is associated with cognitive processing deficits, including deficits in executive processing, that represent a core component of the disorder. In the Task Switching Test, subjects view ambiguous stimuli and must alternate between competing rules to generate correct responses. Subjects show worse performance (prolonged response time and/or increased error rates) on the first response after a switch than on subsequent responses ("switch costs"), as well as performing worse when stimuli are incongruent as opposed to congruent ("congruence costs"). Finally, subjects show worse performance in the dual vs single task condition ("mixing costs"). In monkeys, the N-methyl-D-aspartate (NMDA) antagonist ketamine has been shown to increase congruence but not switch costs. Here, subjects viewed colored letters and had to respond alternately based upon letter (X vs O) or color (red vs blue). Switch, congruence and mixing costs were calculated. Patients with schizophrenia (n = 16) and controls (n = 17) showed similar switch costs, consistent with prior literature. Patients nevertheless showed increased congruence and mixing costs. In addition, relative to controls, patients showed worse performance across conditions in the letter vs color tasks, suggesting deficits in form vs color processing. Overall, while confirming executive dysfunction in schizophrenia, this study indicates that not all aspects of executive control are impaired and that the task switching paradigm may be useful for evaluating neurochemical vs neuroanatomic hypotheses of schizophrenia.

  14. Rotigotine protects against glutamate toxicity in primary dopaminergic cell culture.

    PubMed

    Oster, Sandra; Radad, Khaled; Scheller, Dieter; Hesse, Marlen; Balanzew, Wladimir; Reichmann, Heinz; Gille, Gabriele

    2014-02-05

    In Parkinson disease the degeneration of dopaminergic neurones is believed to lead to a disinhibition of the subthalamic nucleus thus increasing the firing rate of the glutamatergic excitatory projections to the substantia nigra. In consequence, excessive glutamatergic activity will cause excitotoxicity and oxidative stress. In the present study we investigated mechanisms of glutamate toxicity and the neuroprotective potential of the dopamine agonist rotigotine towards dopaminergic neurones in mouse mesencephalic primary culture. Glutamate toxicity was mediated by the N-methyl-d-aspartic acid (NMDA) receptor and accompanied by a strong calcium influx into dopaminergic neurones for which the L-type voltage-sensitive calcium channels play an important role. The rate of superoxide production in the culture was highly increased. Deleterious nitric oxide production did not participate in glutamate-mediated excitotoxicity. Pretreatment of cultures with rotigotine significantly increased the survival of dopaminergic neurones exposed to glutamate. Rotigotine exerted its protective effects via dopamine receptor stimulation (presumably via dopamine D3 receptor) and decreased significantly the production of superoxide radicals. When cultures were preincubated with Phosphoinositol 3-Kinase (PI3K) inhibitors the protective effect of rotigotine was abolished suggesting a decisive role of the PI3K/Akt pathway in rotigotine-mediated neuroprotection. Consistently, exposure to rotigotine induced the activation of Akt by phosphorylation followed by phosphorylation, and thus inactivation, of the pro-apoptotic factor glycogen synthase kinase-3-beta (GSK-3-β). Taken together, our work contributed to elucidating the mechanisms of glutamate toxicity in mesencephalic culture and unravelled the signalling pathways associated with rotigotine-induced neuroprotection against glutamate toxicity in primary dopaminergic cultures. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. Metabotropic and ionotropic glutamate receptors mediate the modulation of acetylcholine release at the frog neuromuscular junction.

    PubMed

    Tsentsevitsky, Andrei; Nurullin, Leniz; Nikolsky, Evgeny; Malomouzh, Artem

    2017-07-01

    There is some evidence that glutamate (Glu) acts as a signaling molecule at vertebrate neuromuscular junctions where acetylcholine (ACh) serves as a neurotransmitter. In this study, performed on the cutaneous pectoris muscle of the frog Rana ridibunda, Glu receptor mechanisms that modulate ACh release processes were analyzed. Electrophysiological experiments showed that Glu reduces both spontaneous and evoked quantal secretion of ACh and synchronizes its release in response to electrical stimulation. Quisqualate, an agonist of ionotropic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic receptors and metabotropic Group I mGlu receptors, also exerted Glu-like inhibitory effects on the secretion of ACh but had no effect on the kinetics of quantal release. Quisqualate's inhibitory effect did not occur when a blocker of Group I mGlu receptors (LY 367385) or an inhibitor of phospholipase C (U73122) was present. An increase in the degree of synchrony of ACh quantal release, such as that produced by Glu, was obtained after application of N-methyl-D-aspartic acid (NMDA). The presence of Group I mGlu and NMDA receptors in the neuromuscular synapse was confirmed by immunocytochemistry. Thus, the data suggest that both metabotropic Group I mGlu receptors and ionotropic NMDA receptors are present at the neuromuscular synapse of amphibians, and that the activation of these receptors initiates different mechanisms for the regulation of ACh release from motor nerve terminals. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  16. Attenuation of behavioral effects of cocaine by the Metabotropic Glutamate Receptor 5 Antagonist 2-Methyl-6-(phenylethynyl)-pyridine in squirrel monkeys: comparison with dizocilpine.

    PubMed

    Lee, Buyean; Platt, Donna M; Rowlett, James K; Adewale, Adepero S; Spealman, Roger D

    2005-03-01

    Growing evidence suggests a role for metabotropic glutamate receptors (mGluRs) in the behavioral effects of cocaine related to its abuse. The mGluR5 subtype, in particular, has come under scrutiny due to its distribution in brain regions associated with drug addiction. This study investigated interactions between the selective mGluR5 antagonist 2-methyl-6-(phenylethynyl)-pyridine (MPEP) and cocaine in squirrel monkeys whose lever-pressing behavior was 1) maintained under a second-order schedule of cocaine self-administration, 2) extinguished and then reinstated by cocaine priming, and 3) controlled by the discriminative stimulus (DS) effects of cocaine. Additional studies determined the effects of MPEP on unconditioned behaviors, coordination, and muscle resistance. In each experiment, the effects of MPEP were compared with those of the N-methyl-d-aspartate antagonist dizocilpine. MPEP attenuated cocaine self-administration, cocaine-induced reinstatement of drug seeking, and the DS effects of cocaine at doses that did not markedly impair motor function or operant behavior in the context of drug discrimination. Dizocilpine also attenuated cocaine self-administration, but it did not significantly alter cocaine-induced reinstatement of drug seeking, and it enhanced rather than attenuated the DS effects of cocaine. The findings point to a significant contribution of mGluR5 mechanisms in the behavioral effects of cocaine related to its abuse and suggest that MPEP has properties of a functional cocaine antagonist, which are not secondary to antagonism at NMDA receptors. The contrasting interactions of MPEP and dizocilpine with cocaine imply that glutamate acting through different metabotropic and ionotropic receptors may modulate the behavioral effects of cocaine in qualitatively different ways.

  17. Effects of the NMDA receptor antagonist memantine on the expression and development of acute opiate dependence as assessed by withdrawal-potentiated startle and hyperalgesia.

    PubMed

    Harris, Andrew C; Rothwell, Patrick E; Gewirtz, Jonathan C

    2008-03-01

    While the N-methyl-D: -aspartate (NMDA) glutamate receptor has been strongly implicated in chronic opiate dependence, relatively few studies have examined the effects of NMDA receptor antagonists on withdrawal from acute opiate exposure. The current study examined the effects of memantine, a well-tolerated NMDA receptor antagonist, on acute opiate dependence as assessed by elevations in rodent startle responding (i.e., "withdrawal-potentiated startle") and increased pain sensitivity (i.e., hyperalgesia). Administration of memantine either attenuated (5 mg/kg) or blocked (10 mg/kg) the expression of withdrawal-potentiated startle during naloxone (2.5 mg/kg)-precipitated withdrawal from a single dose of morphine sulfate (10 mg/kg). Pre-treatment with the NMDA receptor antagonist also inhibited the exacerbation of withdrawal-potentiated startle across repeated acute opiate exposures. Memantine blocked the expression of acute dependence, but was less effective in inhibiting its escalation, when hyperalgesia was used as a measure of withdrawal. These doses of memantine did not affect startle responding or nociception in otherwise drug-free animals. Data from additional control groups indicated that the effects of memantine on the expression of withdrawal were not influenced by nonspecific interactions between the NMDA antagonist and either morphine or naloxone. These findings suggest that the NMDA receptor may play a key role in the earliest stages of opiate dependence and provide further evidence that memantine may be useful for the treatment of opiate withdrawal.

  18. Activation of NMDA receptor by elevated homocysteine in chronic liver disease contributes to encephalopathy.

    PubMed

    Choudhury, Sabanum; Borah, Anupom

    2015-07-01

    Liver diseases lead to a complex syndrome characterized by neurological, neuro-psychiatric and motor complications, called hepatic encephalopathy, which is prevalent in patients and animal models of acute, sub-chronic and chronic liver failure. Although alterations in GABAergic, glutamatergic, cholinergic and serotonergic neuronal functions have been implicated in HE, the molecular mechanisms that lead to HE in chronic liver disease (CLD) is least illustrated. Due to hepatocellular failure, levels of ammonia and homocysteine (Hcy), in addition to others, are found to increase in the brain as well as plasma. Hcy, a non-protein forming amino acid and an excitotoxin, activates ionotropic glutamate (n-methyl-d-aspartate; NMDA) receptors, and thereby leads to influx of Ca(2+) into neurons, which in turn activates several pathways that trigger oxidative stress, inflammation and apoptosis, collectively called excitotoxicity. Elevated levels of Hcy in the plasma and brain, a condition called Hyperhomocysteinemia (HHcy), and the resultant NMDA receptor-mediated excitotoxicity has been implicated in several diseases, including Parkinson's disease and Alzheimer's disease. Although, hyperammonemia has been shown to cause excitotoxicity, the role of HHcy in the development of behavioral and neurochemical alterations that occur in HE has not been illustrated yet. It is hypothesized that CLD-induced HHcy plays a major role in the development of HE through activation of NMDA receptors. It is further hypothesized that HHcy synergizes with hyperammonemia to activate NMDA receptor in the brain, and thereby cause oxidative stress, inflammation and apoptosis, and neuronal loss that leads to HE. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. D-cycloserine adjuvant therapy to molindone in the treatment of schizophrenia.

    PubMed

    Rosse, R B; Fay-McCarthy, M; Kendrick, K; Davis, R E; Deutsch, S I

    1996-10-01

    This preliminary investigation examined the therapeutic efficacy of two doses of oral D-cycloserine (5 and 15 mg p.o. b.i.d.) administered as an adjuvant to molindone (150 mg p.o. q.d.) in the treatment of schizophrenia. D-Cycloserine is an agonist at the N-methyl-D-aspartate (NMDA) subclass of glutamate receptor complex. An NMDA agonist intervention was studied because of the schizophreniform psychosis precipitated by phencyclidine (PCP), which is a noncompetitive antagonist at the NMDA glutamate receptor. The PCP model of schizophrenia is regarded as the most comprehensive pharmacological model of this disorder. In this preliminary, placebo-controlled, double-blind, parallel-group study, the measures of treatment efficacy were the Brief Psychiatric Rating Scale, Schedule for the Assessment of Negative Symptoms, and Clinical Global Impression Scale. The final scores for each item of the outcome measures employed were based on the consensus of at least two trained raters who were present during each rating interview. In the 13 subjects evaluated, although the D-cycloserine was well tolerated, neither dose seemed to possess adjuvant therapeutic efficacy. However, since another recent report of nine patients with schizophrenia treated for 2 weeks with a slightly higher dose of D-cycloserine (50 mg/day) described significant clinical and neuropsychological improvement, further study of the adjuvant potential of slightly higher doses of D-cycloserine seems warranted. Additionally, there might be a therapeutic window for D-cycloserine dosing, as daily doses of 250 mg have been associated with symptom worsening.

  20. Dynamics of Learning in Cultured Neuronal Networks with Antagonists of Glutamate Receptors

    PubMed Central

    Li, Yanling; Zhou, Wei; Li, Xiangning; Zeng, Shaoqun; Luo, Qingming

    2007-01-01

    Cognitive dysfunction may result from abnormality of ionotropic glutamate receptors. Although various forms of synaptic plasticity in learning that rely on altering of glutamate receptors have been considered, the evidence is insufficient from an informatics view. Dynamics could reflect neuroinformatics encoding, including temporal pattern encoding, spatial pattern encoding, and energy distribution. Discovering informatics encoding is fundamental and crucial to understanding the working principle of the neural system. In this article, we analyzed the dynamic characteristics of response activities during learning training in cultured hippocampal networks under normal and abnormal conditions of ionotropic glutamate receptors, respectively. The rate, which is one of the temporal configurations, was decreased markedly by inhibition of α-amino-3-hydroxy-5-methylisoxazole-4-proprionic acid (AMPA) receptors. Moreover, the energy distribution in different characteristic frequencies was changed markedly by inhibition of AMPA receptors. Spatial configurations, including regularization, correlation, and synchrony, were changed significantly by inhibition of N-methyl-d-aspartate receptors. These results suggest that temporal pattern encoding and energy distribution of response activities in cultured hippocampal neuronal networks during learning training are modulated by AMPA receptors, whereas spatial pattern encoding of response activities is modulated by N-methyl-d-aspartate receptors. PMID:17766359

  1. Metabotropic glutamate receptor 5 upregulates surface NMDA receptor expression in striatal neurons via CaMKII.

    PubMed

    Jin, Dao-Zhong; Xue, Bing; Mao, Li-Min; Wang, John Q

    2015-10-22

    Metabotropic and ionotropic glutamate receptors are closely clustered in postsynaptic membranes and are believed to interact actively with each other to control excitatory synaptic transmission. Metabotropic glutamate receptor 5 (mGluR5), for example, has been well documented to potentiate ionotropic NMDA receptor activity, although underlying mechanisms are poorly understood. In this study, we investigated the role of mGluR5 in regulating trafficking and subcellular distribution of NMDA receptors in adult rat striatal neurons. We found that the mGluR1/5 agonist DHPG concentration-dependently increased NMDA receptor GluN1 and GluN2B subunit expression in the surface membrane. Meanwhile, DHPG reduced GluN1 and GluN2B levels in the intracellular compartment. The effect of DHPG was blocked by an mGluR5 selective antagonist MTEP but not by an mGluR1 selective antagonist 3-MATIDA. Pretreatment with an inhibitor or a specific inhibitory peptide for synapse-enriched Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) also blocked the DHPG-stimulated redistribution of GluN1 and GluN2B. In addition, DHPG enhanced CaMKIIα activity and elevated GluN2B phosphorylation at a CaMKII-sensitive site (serine 1303). These results demonstrate that mGluR5 regulates trafficking of NMDA receptors in striatal neurons. Activation of mGluR5 appears to induce rapid trafficking of GluN1 and GluN2B to surface membranes through a signaling pathway involving CaMKII. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Medial prefrontal cortex TRPV1 and CB1 receptors modulate cardiac baroreflex activity by regulating the NMDA receptor/nitric oxide pathway.

    PubMed

    Lagatta, Davi C; Kuntze, Luciana B; Ferreira-Junior, Nilson C; Resstel, Leonardo B M

    2018-05-29

    The ventral medial prefrontal cortex (vMPFC) facilitates the cardiac baroreflex response through N-methyl-D-aspartate (NMDA) receptor activation and nitric oxide (NO) formation by neuronal NO synthase (nNOS) and soluble guanylate cyclase (sGC) triggering. Glutamatergic transmission is modulated by the cannabinoid receptor type 1 (CB 1 ) and transient receptor potential vanilloid type 1 (TRPV 1 ) receptors, which may inhibit or stimulate glutamate release in the brain, respectively. Interestingly, vMPFC CB 1 receptors decrease cardiac baroreflex responses, while TRPV 1 channels facilitate them. Therefore, the hypothesis of the present study is that the vMPFC NMDA/NO pathway is regulated by both CB 1 and TRPV 1 receptors in the modulation of cardiac baroreflex activity. In order to test this assumption, we used male Wistar rats that had stainless steel guide cannulae bilaterally implanted in the vMPFC. Subsequently, a catheter was inserted into the femoral artery, for cardiovascular recordings, and into the femoral vein for assessing baroreflex activation. The increase in tachycardic and bradycardic responses observed after the microinjection of a CB 1 receptors antagonist into the vMPFC was prevented by an NMDA antagonist as well as by the nNOS and sGC inhibition. NO extracellular scavenging also abolished these responses. These same pharmacological manipulations inhibited cardiac reflex enhancement induced by TRPV 1 agonist injection into the area. Based on these results, we conclude that vMPFC CB 1 and TRPV 1 receptors inhibit or facilitate the cardiac baroreflex activity by stimulating or blocking the NMDA activation and NO synthesis.

  3. Single-Molecule Patch-Clamp FRET Anisotropy Microscopy Studies of NMDA Receptor Ion Channel Activation and Deactivation under Agonist Ligand Binding in Living Cells.

    PubMed

    Sasmal, Dibyendu Kumar; Yadav, Rajeev; Lu, H Peter

    2016-07-20

    N-methyl-d-aspartate (NMDA) receptor ion channel is activated by the binding of two pairs of glycine and glutamate along with the application of action potential. Binding and unbinding of ligands changes its conformation that plays a critical role in the open-close activities of NMDA receptor. Conformation states and their dynamics due to ligand binding are extremely difficult to characterize either by conventional ensemble experiments or single-channel electrophysiology method. Here we report the development of a new correlated technical approach, single-molecule patch-clamp FRET anisotropy imaging and demonstrate by probing the dynamics of NMDA receptor ion channel and kinetics of glycine binding with its ligand binding domain. Experimentally determined kinetics of ligand binding with receptor is further verified by computational modeling. Single-channel patch-clamp and four-channel fluorescence measurement are recorded simultaneously to get correlation among electrical on and off states, optically determined conformational open and closed states by FRET, and binding-unbinding states of the glycine ligand by anisotropy measurement at the ligand binding domain of GluN1 subunit. This method has the ability to detect the intermediate states in addition to electrical on and off states. Based on our experimental results, we have proposed that NMDA receptor gating goes through at least one electrically intermediate off state, a desensitized state, when ligands remain bound at the ligand binding domain with the conformation similar to the fully open state.

  4. Epileptogenesis causes an N-methyl-d-aspartate receptor/Ca2+-dependent decrease in Ca2+/calmodulin-dependent protein kinase II activity in a hippocampal neuronal culture model of spontaneous recurrent epileptiform discharges.

    PubMed

    Blair, Robert E; Sombati, Sompong; Churn, Severn B; Delorenzo, Robert J

    2008-06-24

    Alterations in the function of Ca2+/calmodulin-dependent protein kinase II (CaM kinase II) have been observed in both in vivo and in vitro models of epileptogenesis; however the molecular mechanism mediating the effects of epileptogenesis on CaM kinase II has not been elucidated. This study was initiated to evaluate the molecular pathways involved in causing the long-lasting decrease in CaM kinase II activity in the hippocampal neuronal culture model of low Mg2+-induced spontaneous recurrent epileptiform discharges (SREDs). We show here that the decrease in CaM kinase II activity associated with SREDs in hippocampal cultures involves a Ca2+/N-methyl-d-aspartate (NMDA) receptor-dependent mechanism. Low Mg2+-induced SREDs result in a significant decrease in Ca2+/calmodulin-dependent substrate phosphorylation of the synthetic peptide autocamtide-2. Reduction of extracellular Ca2+ levels (0.2 mM in treatment solution) or the addition of dl-2-amino-5-phosphonovaleric acid (APV) 25 microM blocked the low Mg2+-induced decrease in CaM kinase II-dependent substrate phosphorylation. Antagonists of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)/kainic acid receptor or L-type voltage sensitive Ca2+ channel had no effect on the low Mg2+-induced decrease in CaM kinase II-dependent substrate phosphorylation. The results of this study demonstrate that the decrease in CaM kinase II activity associated with this model of epileptogenesis involves a selective Ca2+/NMDA receptor-dependent mechanism and may contribute to the production and maintenance of SREDs in this model.

  5. Epileptogenesis causes an N-methyl-d-aspartate receptor/Ca2+-dependent decrease in Ca2+/calmodulin-dependent protein kinase II activity in a hippocampal neuronal culture model of spontaneous recurrent epileptiform discharges

    PubMed Central

    Blair, Robert E.; Sombati, Sompong; Churn, Severn B.; DeLorenzo, Robert J.

    2008-01-01

    Alterations in the function of Ca2+/calmodulin-dependent protein kinase II (CaM Kinase II) have been observed in both in vivo and in vitro models of epileptogenesis; however the molecular mechanism mediating the effects of epileptogenesis on CaM Kinase II have not been elucidated. This study was initiated to evaluate the molecular pathways involved in causing the long lasting decrease in CaM Kinase II activity in the hippocampal neuronal culture model of low Mg2+ induced spontaneous recurrent epileptiform discharges (SREDs). We show here that the decrease in CaM kinase II activity associated with SREDs in hippocampal cultures involves a Ca2+/N-methyl-d-aspartate (NMDA) receptor-dependent mechanism. Low Mg2+ induced SREDs results in a significant decrease in Ca2+/calmodulin-dependent substrate phosphorylation of the synthetic peptide autocamtide-2. Reduction of extracellular Ca2+ levels (0.2 mM in treatment solution) or the addition of DL-2-amino-5-phosphonovaleric acid (APV) 25 µM blocked the low Mg2+ induced decrease in CaM kinase II-dependent substrate phosphorylation. Antagonists of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)/kainic acid receptor or L-type voltage sensitive Ca2+ channel had no effect on the low Mg2+ induced decrease in CaM kinase II-dependent substrate phosphorylation. The results of this study demonstrate that the decrease in CaM kinase II activity associated with this model of epileptogenesis involves a selective Ca2+/NMDA receptor-dependent mechanism and may contribute to the production and maintenance of SREDs in this model. PMID:18495112

  6. STEP activation by Gαq coupled GPCRs opposes Src regulation of NMDA receptors containing the GluN2A subunit

    PubMed Central

    Tian, Meng; Xu, Jian; Lei, Gang; Lombroso, Paul J.; Jackson, Michael F.; MacDonald, John F.

    2016-01-01

    N-methyl-D-aspartate receptors (NMDARs) are necessary for the induction of synaptic plasticity and for the consolidation of learning and memory. NMDAR function is tightly regulated by functionally opposed families of kinases and phosphatases. Herein we show that the striatal-enriched protein tyrosine phosphatase (STEP) is recruited by Gαq-coupled receptors, including the M1 muscarinic acetylcholine receptor (M1R), and opposes the Src tyrosine kinase-mediated increase in the function of NMDARs composed of GluN2A. STEP activation by M1R stimulation requires IP3Rs and can depress NMDA-evoked currents with modest intracellular Ca2+ buffering. Src recruitment by M1R stimulation requires coincident NMDAR activation and can augment NMDA-evoked currents with high intracellular Ca2+ buffering. Our findings suggest that Src and STEP recruitment is contingent on differing intracellular Ca2+ dynamics that dictate whether NMDAR function is augmented or depressed following M1R stimulation. PMID:27857196

  7. Glutamatergic targets for new alcohol medications

    PubMed Central

    Spanagel, Rainer; Krystal, John H.

    2013-01-01

    Rationale An increasingly compelling literature points to a major role for the glutamate system in mediating the effects of alcohol on behavior and the pathophysiology of alcoholism. Preclinical studies indicate that glutamate signaling mediates certain aspects of ethanol’s intoxicating and rewarding effects, and undergoes adaptations following chronic alcohol exposure that may contribute to the withdrawal, craving and compulsive drug-seeking that drive alcohol abuse and alcoholism. Objectives We discuss the potential for targeting the glutamate system as a novel pharmacotherapeutic approach to treating alcohol use disorders, focusing on five major components of the glutamate system: the N-methyl-D-aspartate (NMDA) receptor and specific NMDA subunits, the glycineB site on the NMDA receptors (NMDAR), L-alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid ionotropic (AMPA) and kainate (KAR) receptors, metabotropic receptors (mGluR), and glutamate transporters. Results Chronic alcohol abuse produces a hyperglutamatergic state, characterized by elevated extracellular glutamate and altered glutamate receptors and transporters. Pharmacologically manipulating glutamatergic neurotransmission alters alcohol-related behaviors including intoxication, withdrawal, and alcohol-seeking, in rodents and human subjects. Blocking NMDA and AMPA receptors reduces alcohol consumption in rodents, but side-effects may limit this as a therapeutic approach. Selectively targeting NMDA and AMPA receptor subunits (e.g., GluN2B, GluA3), or the NMDAR glycineB site offers an alternative approach. Blocking mGluR5 potently affects various alcohol-related behaviors in rodents, and mGluR2/3 agonism also suppresses alcohol consumption. Finally, glutamate transporter upregulation may mitigate behavioral and neurotoxic sequelae of excess glutamate caused by alcohol. Conclusions Despite the many challenges that remain, targeting the glutamate system offers genuine promise for developing new

  8. Cortical ionotropic glutamate receptor antagonism protects against methamphetamine-induced striatal neurotoxicity.

    PubMed

    Gross, N B; Duncker, P C; Marshall, J F

    2011-12-29

    Binge administration of the psychostimulant drug, methamphetamine (mAMPH), produces long-lasting structural and functional abnormalities in the striatum. mAMPH binges produce nonexocytotic release of dopamine (DA), and mAMPH-induced activation of excitatory afferent inputs to cortex and striatum is evidenced by elevated extracellular glutamate (GLU) in both regions. The mAMPH-induced increases in DA and GLU neurotransmission are thought to combine to injure striatal DA nerve terminals of mAMPH-exposed brains. Systemic pretreatment with either competitive or noncompetitive N-methyl-D-aspartic acid (NMDA) antagonists protects against mAMPH-induced striatal DA terminal damage, but the locus of these antagonists' effects has not been determined. Here, we applied either the NMDA receptor antagonist, (dl)-amino-5-phosphonovaleric acid (AP5), or the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor antagonist, dinitroquinoxaline-2,3-dione (DNQX), directly to the dura mater over frontoparietal cortex to assess their effects on mAMPH-induced cortical and striatal immediate-early gene (c-fos) expression. In a separate experiment we applied AP5 or DNQX epidurally in the same cortical location of rats during a binge regimen of mAMPH and assessed mAMPH-induced striatal dopamine transporter (DAT) depletions 1 week later. Our results indicate that both ionotropic glutamate receptor antagonists reduced the mAMPH-induced Fos expression in cerebral cortex regions near the site of epidural application and reduced Fos immunoreactivity in striatal regions innervated by the affected cortical regions. Also, epidural application of the same concentration of either antagonist during a binge mAMPH regimen blunted the mAMPH-induced striatal DAT depletions with a topography similar to its effects on Fos expression. These findings demonstrate that mAMPH-induced dopaminergic injury depends upon cortical NMDA and AMPA receptor activation and suggest the involvement of the

  9. The major brain cholesterol metabolite 24(S)-hydroxycholesterol is a potent allosteric modulator of N-methyl-D-aspartate receptors.

    PubMed

    Paul, Steven M; Doherty, James J; Robichaud, Albert J; Belfort, Gabriel M; Chow, Brian Y; Hammond, Rebecca S; Crawford, Devon C; Linsenbardt, Andrew J; Shu, Hong-Jin; Izumi, Yukitoshi; Mennerick, Steven J; Zorumski, Charles F

    2013-10-30

    N-methyl-D-aspartate receptors (NMDARs) are glutamate-gated ion channels that are critical to the regulation of excitatory synaptic function in the CNS. NMDARs govern experience-dependent synaptic plasticity and have been implicated in the pathophysiology of various neuropsychiatric disorders including the cognitive deficits of schizophrenia and certain forms of autism. Certain neurosteroids modulate NMDARs experimentally but their low potency, poor selectivity, and very low brain concentrations make them poor candidates as endogenous ligands or therapeutic agents. Here we show that the major brain-derived cholesterol metabolite 24(S)-hydroxycholesterol (24(S)-HC) is a very potent, direct, and selective positive allosteric modulator of NMDARs with a mechanism that does not overlap that of other allosteric modulators. At submicromolar concentrations 24(S)-HC potentiates NMDAR-mediated EPSCs in rat hippocampal neurons but fails to affect AMPAR or GABAA receptors (GABA(A)Rs)-mediated responses. Cholesterol itself and other naturally occurring oxysterols present in brain do not modulate NMDARs at concentrations ≤10 μM. In hippocampal slices, 24(S)-HC enhances the ability of subthreshold stimuli to induce long-term potentiation (LTP). 24(S)-HC also reverses hippocampal LTP deficits induced by the NMDAR channel blocker ketamine. Finally, we show that synthetic drug-like derivatives of 24(S)-HC, which potently enhance NMDAR-mediated EPSCs and LTP, restore behavioral and cognitive deficits in rodents treated with NMDAR channel blockers. Thus, 24(S)-HC may function as an endogenous modulator of NMDARs acting at a novel oxysterol modulatory site that also represents a target for therapeutic drug development.

  10. 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. © The Author(s) 2016.

  11. Functional characterization of α7 nicotinic acetylcholine and NMDA receptor signaling in SH-SY5Y neuroblastoma cells in an ERK phosphorylation assay.

    PubMed

    Elnagar, Mohamed R; Walls, Anne Byriel; Helal, Gouda K; Hamada, Farid M; Thomsen, Morten Skøtt; Jensen, Anders A

    2018-05-05

    In the present study, the functional properties of α7 nicotinic acetylcholine receptors (α7 nAChRs) and N-methyl-D-aspartate receptors (NMDARs) endogenously expressed in SH-SY5Y human neuroblastoma cells were characterized in an extracellular-signal regulated kinase (ERK) phosphorylation assay. Both choline and N-methyl-D-aspartate (NMDA) mediated robust concentration-dependent increases in ERK phosphorylation in the SH-SY5Y cells, exhibiting EC 50 values in good agreement with those reported for the agonists at recombinant α7 nAChRs and NMDARs, respectively. Importantly, the responses evoked by choline (10 mM) and by NMDA (50 μM) were significantly inhibited by the α7-selective antagonist α-bungarotoxin (100 nM) and by the NMDAR-selective antagonist MK-801 (50 μM), respectively. The increased ERK phosphorylation levels observed upon co-application of choline (1, 3, 10 mM) and NMDA (50 μM) compared to those produced by the two agonists on their own were fully reconcilable with additive effects and did not reveal substantial synergy between α7 nAChR and NMDAR signaling. Interestingly, however, the responses evoked by the "choline (10 mM) - NMDA (50 μM)" combination were almost completely inhibited by α-bungarotoxin (100 nM) as well as by MK-801 (50 μM), suggesting some sort of a link between α7 nAChR- and NMDAR-mediated ERK phosphorylation. Finally, oligomeric amyloid-β 1-42 peptide (1000 nM) mediated robust inhibition of the ERK phosphorylation induced by choline (10 mM), NMDA (50 μM) and the "choline (10 mM) - NMDA (50 μM)" combination. In conclusion, ERK phosphorylation measurements in SH-SY5Y cells provides a robust assay for studies of α7 nAChR- and NMDAR-mediating signaling and putative functional interactions between the receptors. Copyright © 2018 Elsevier B.V. All rights reserved.

  12. Neuropeptide S attenuates neuropathological, neurochemical and behavioral changes induced by the NMDA receptor antagonist MK-801

    PubMed Central

    Okamura, Naoe; Reinscheid, Rainer K.; Ohgake, Shintaro; Iyo, Masaomi; Hashimoto, Kenji

    2009-01-01

    Neuropeptide S (NPS) and its cognate receptor were reported to mediate anxiolytic-like and arousal effects. NPS receptors are predominantly expressed in the brain, especially in limbic structures, including amygdala, olfactory nucleus, subiculum and retrosplenial cortex. In contrast, the NPS precursor is expressed in only a few brainstem nuclei where it is co-expressed with various excitatory transmitters, including glutamate. The current study investigates interactions of the NPS system with glutamatergic neurotransmission. It has been suggested that dysfunctions in glutamatergic neurotransmission via N-methyl-D-aspartate (NMDA) receptors might be involved in the pathophysiology of schizophrenia since NMDA receptor antagonists, such as MK-801, have been shown to induce psychotic-like behavior in humans and animal models. Also, MK-801 is known to produce histological changes such as cytoplasmic vacuoles in retrosplenial cortex neurons where NPS receptors are highly expressed. In this study we show that NPS is able to alleviate neuropathological, neurochemical and behavioral changes produced by NMDA receptor antagonists. NPS treatment attenuated MK-801-induced vacuolization in the rat retrosplenial cortex in a dose dependent manner that can be blocked by an NPS receptor-selective antagonist. NPS also suppressed MK-801-induced increases of extracellular acetylcholine levels in the retrosplenial cortex. In the prepulse inhibition (PPI) assay, animals pretreated with NPS recovered significantly from MK-801-induced disruption of PPI. Our study suggests that NPS may have protective effects against the neurotoxic and behavioral changes produced by NMDA receptor antagonists and that NPS receptor agonists may elicit antipsychotic effects. PMID:19576911

  13. Decursinol and decursin protect primary cultured rat cortical cells from glutamate-induced neurotoxicity.

    PubMed

    Kang, So Young; Kim, Young Choong

    2007-06-01

    We previously reported six neuroprotective decursinol derivatives, coumarins from Angelica gigas (Umbelliferae) roots. To elucidate the action patterns of decursinol derivatives, we investigated the neuroprotective effects of decursinol and decursin, which showed highly significant activity and were major constituents of A. gigas, using primary cultures of rat cortical cells in-vitro. At concentrations of 0.1-10.0 microM, both decursinol and decursin exerted a significant neuroprotective activity pretreatment and throughout treatment. In addition, decursin had a neuroprotective impact in the post-treatment paradigm implying that decursin might possess different action mechanisms from that of decursinol in the protection of neurons against glutamate injury. Both decursinol and decursin effectively reduced the glutamate-induced increased intracellular calcium ([Ca(2+)](i)) in cortical cells, suggesting that these two coumarins may exert neuroprotection by reducing calcium influx by overactivation of glutamate receptors. This suggestion was supported by the result that decursinol and decursin protected neurons against kainic acid (KA)-induced neurotoxicity better than against that induced by N-methyl-D-aspartate (NMDA). Moreover, both decursinol and decursin significantly prevented glutamate-induced decreases in glutathione, a cellular antioxidant, and glutathione peroxidase activity. In addition, both compounds efficiently reduced the overproduction of cellular peroxide in glutamate-injured cortical cells. These results suggested that both decursinol and decursin protected primary cultured rat cortical cells against glutamate-induced oxidative stress by both reducing calcium influx and acting on the cellular antioxidative defence system. Moreover, decursin is considered to probably have a different action mechanism from that of decursinol in protecting cortical cells against glutamate injury.

  14. Exploring neuroprotective potential of Withania somnifera phytochemicals by inhibition of GluN2B-containing NMDA receptors: An in silico study.

    PubMed

    Kumar, Gaurav; Patnaik, Ranjana

    2016-07-01

    N-methyl-d-aspartate receptors (NMDARs) mediated excitotoxicity has been implicated in multi-neurodegenerative diseases. Due to lack of efficacy and adverse effects of NMDA receptor antagonists, search for herbal remedies that may act as therapeutic agents is an active area of research to combat these diseases. Withania somnifera (WS) is being used for centuries as a nerve tonic and Nootropic agents. The present study targets the in silico evaluation of the neuroprotective efficacy of W. somnifera phytochemicals by inhibition of NMDA receptor-mediated excitotoxicity through allosteric inhibition of the GluN2B containing NMDARs. We predict Blood Brain Barrier (BBB) penetration, mutagenicity, drug-likeness and Human Intestinal Absorption properties of 25 WS phytochemicals. Further, molecular docking was performed to know whether these phytochemicals inhibit the GluN2B containing NMDARs or not. The results suggest that Anaferine, Beta-Sitosterol, Withaferin A, Withanolide A, Withanolide B and Withanolide D inhibit GluN2B containing NMDARs through allosteric mode similar to the well-known selective antagonist Ifenprodil. These phytochemicals have potential as an essentially useful oral drug to counter NMDARs mediated excitotoxicity and to treat multi-neurodegenerative diseases. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

    PubMed

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

    2015-01-01

    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. 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. Postsynaptic density-enriched fractions were isolated from fresh-frozen prefrontal cortex (BA10) and subjected to western blot analysis for NR1 and PSD-95. 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. 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.

  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.

  17. NMDA receptor-antagonistic properties of hyperforin, a constituent of St. John's Wort.

    PubMed

    Kumar, Vikas; Mdzinarishvili, Alexander; Kiewert, Cornelia; Abbruscato, Thomas; Bickel, Ulrich; van der Schyf, Cornelis J; Klein, Jochen

    2006-09-01

    Extracts of the medicinal plant St. John's wort (Hypericum perforatum) are widely used for the treatment of affective disorders. Hyperforin, a constituent of St. John's wort, is known to modulate the release and re-uptake of various neurotransmitters, an action that likely underlies its antidepressive activity. We now report that hyperforin also has N-methyl-D-aspartate (NMDA)-antagonistic effects. Hyperforin (10 microM) was found to inhibit the NMDA-induced calcium influx into cortical neurons. In rat hippocampal slices, hyperforin inhibited the NMDA-receptor-mediated release of choline from phospholipids. Hyperforin also antagonized the increase of water content in freshly isolated hippocampal slices, and it counteracted, at 3 and 10 microM, the increase of water content induced by NMDA. Hyperforin was inactive, however, in two in vivo models of brain edema formation, middle cerebral artery occlusion and water intoxication in mice. In conclusion, hyperforin has NMDA-receptor-antagonistic and potential neuroprotective effects in vitro. This effect may contribute to the therapeutic effectiveness of St. John's wort extracts in some situations, for example, for relapse prevention in alcoholism.

  18. Evidence that NMDA-dependent limbic neural plasticity in the right hemisphere mediates pharmacological stressor (FG-7142)-induced lasting increases in anxiety-like behavior. Study 2--The effects on behavior of block of NMDA receptors prior to injection of FG-7142.

    PubMed

    Adamec, R E

    1998-01-01

    The hypothesis that N-methyl-D-aspartate (NMDA) receptors mediate initiation of lasting behavioral changes induced by the anxiogenic beta-carboline, FG-7142, was supported in this study. Behavioral changes normally induced by FG-7142 were blocked when the competitive NMDA receptor blocker, 7-amino-phosphono-heptanoic acid, was given prior to administration of FG-7142. When cats were subsequently given FG-7142 alone, the drug produced lasting behavioral changes like those reported previously. Flumazenil, a benzodiazepine receptor antagonist, reversed an increase in defensiveness produced by FG-7142 alone, replicating previous findings. The data are consistent with the hypothesis that NMDA-dependent long-term potentiation in limbic pathways subserving defensive response to threat mediates lasting increases in defensiveness produced by FG-7142.

  19. The N-Methyl-D-Aspartate Receptor in Heart Development: A Gene Knockdown Model Using siRNA

    PubMed Central

    Lie, Octavian V.; Bennett, Gregory D.; Rosenquist, Thomas H

    2009-01-01

    Antagonists of the N-methyl-D-aspartate receptor (NMDAR) may disrupt the development of the cardiac neural crest (CNC) and contribute to conotruncal heart defects. To test this interaction, a loss-of-function model was generated using small interfering RNAs (siRNA) directed against the critical NR1-subunit of this receptor in avian embryos. The coding sequence of the chicken NR1-gene and predicted protein sequences were characterized and found to be homologous with other vertebrate species. Analysis of its spatiotemporal expression demonstrated its expression within the neural tube at pre-migratory CNC sites. siRNA targeted to the NR1-mRNA in pre-migratory CNC lead to a significant decrease in NR1 protein expression. However, embryo survival and heart development were not adversely affected. These results indicate that the CNC may function normally in the absence of functional NMDAR, and that NMDAR antagonists may have a complex impact upon the CNC that transcends impairment of a single receptor type. PMID:19737608

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

    PubMed

    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.

  1. NMDA Receptor Activity in Circulating Red Blood Cells: Methods of Detection.

    PubMed

    Makhro, Asya; Kaestner, Lars; Bogdanova, Anna

    2017-01-01

    Abundance and activity of N-methyl-D-aspartate (NMDA) in circulating red blood cells contributes to the maintenance of intracellular Ca 2+ in these cells and, by doing that, controls red cell volume, membrane stability, and O 2 carrying capacity. Detection of the NMDA receptor activity in red blood cells is challenging as the number of its copies is low and shows substantial cell-to-cell heterogeneity. Receptor abundance is reliably assessed using the radiolabeled antagonist ([ 3 H]MK-801) binding technique. Uptake of Ca 2+ following the NMDA receptor activation is detected in cells loaded with Ca 2+ -sensitive fluorescent dye Fluo-4 AM. Both microfluorescence live-cell imaging and flow cytometry may be used for fluorescence intensity detection. Automated patch clamp is currently used for recording of electric currents triggered by the stimulation of the NMDA receptor. These currents are mediated by the Ca 2+ -sensitive K + (Gardos) channels that open upon Ca 2+ uptake via the active NMDA receptor. Furthermore, K + flux through the Gardos channels induced by the NMDA receptor stimulation in red blood cells may be detected using unidirectional K + ( 86 Rb + ) influx.

  2. 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

  3. Histone methylation at gene promoters is associated with developmental regulation and region-specific expression of ionotropic and metabotropic glutamate receptors in human brain.

    PubMed

    Stadler, Florian; Kolb, Gabriele; Rubusch, Lothar; Baker, Stephen P; Jones, Edward G; Akbarian, Schahram

    2005-07-01

    Glutamatergic signaling is regulated, in part, through differential expression of NMDA and AMPA/KA channel subunits and G protein-coupled metabotropic receptors. In human brain, region-specific expression patterns of glutamate receptor genes are maintained over the course of decades, suggesting a role for molecular mechanisms involved in long-term regulation of transcription, including methylation of lysine residues at histone N-terminal tails. Using a native chromatin immunoprecipitation assay, we studied histone methylation marks at proximal promoters of 16 ionotropic and metabotropic glutamate receptor genes (GRIN1,2A-D; GRIA1,3,4; GRIK2,4,5; GRM1,3,4,6,7 ) in cerebellar cortex collected across a wide age range from midgestation to 90 years old. Levels of di- and trimethylated histone H3-lysine 4, which are associated with open chromatin and transcription, showed significant differences between promoters and a robust correlation with corresponding mRNA levels in immature and mature cerebellar cortex. In contrast, levels of trimethylated H3-lysine 27 and H4-lysine 20, two histone modifications defining silenced or condensed chromatin, did not correlate with transcription but were up-regulated overall in adult cerebellum. Furthermore, differential gene expression patterns in prefrontal and cerebellar cortex were reflected by similar differences in H3-lysine 4 methylation at promoters. Together, these findings suggest that histone lysine methylation at gene promoters is involved in developmental regulation and maintenance of region-specific expression patterns of ionotropic and metabotropic glutamate receptors. The association of a specific epigenetic mark, H3-(methyl)-lysine 4, with the molecular architecture of glutamatergic signaling in human brain has potential implications for schizophrenia and other disorders with altered glutamate receptor function.

  4. Neonatal olfactory bulbectomy enhances locomotor activity, exploratory behavior and binding of NMDA receptors in pre-pubertal rats.

    PubMed

    Flores, G; Ibañez-Sandoval, O; Silva-Gómez, A B; Camacho-Abrego, I; Rodríguez-Moreno, A; Morales-Medina, J C

    2014-02-14

    In this study, we investigated the effect of neonatal olfactory bulbectomy (nOBX) on behavioral paradigms related to olfaction such as exploratory behavior, locomotor activity in a novel environment and social interaction. We also studied the effect of nOBX on the activity of the N-methyl-d-aspartate (NMDA) subtype of glutamate receptors during development. The behavioral effects of nOBX (postnatal day 7, PD7) were investigated in pre- (PD30) and post-pubertal (PD60) Wistar rats. NMDA receptor activity was measured with [(125)I]MK-801 in the brain regions associated with the olfactory circuitry. A significant increase in the novelty-induced locomotion was seen in the pre-pubertal nOBX rats. Although the locomotor effect was less marked than in pre-pubertal rats, the nOBX rats tested post-pubertally failed to habituate to the novel situation as quickly as the sham- and normal- controls. Pre-pubertally, the head-dipping behavior was enhanced in nOBX rats compared with sham-operated and normal controls, while normal exploratory behavior was observed between groups in adulthood. In contrast, social interaction was increased in post-pubertal animals that underwent nOBX. Both pre- and post-pubertal nOBX rats recovered olfaction. Interestingly, pre-pubertal rats showed a significant increase in the [(125)I]MK-801 binding in the piriform cortex, dorsal hippocampus, inner and outer layers of the frontal cortex and outer layer of the cingulate cortex. At post-pubertal age, no significant differences in [(125)I]MK-801 binding were observed between groups at any of the brain regions analyzed. These results suggest that nOBX produces pre-pubertal behavioral disturbances and NMDA receptor changes that are transitory with recovery of olfaction early in adulthood. Copyright © 2013 IBRO. Published by Elsevier Ltd. All rights reserved.

  5. The effect of 1800MHz radio-frequency radiation on NMDA receptor subunit NR1 expression and peroxidation in the rat brain in healthy and inflammatory states.

    PubMed

    Bodera, Paweł; Makarova, Katerina; Zawada, Katarzyna; Antkowiak, Bożena; Paluch, Małgorzata; Sobiczewska, Elżbieta; Sirav, Bahriye; Siwicki, Andrzej K; Stankiewicz, Wanda

    2017-08-01

    The aim of this study was to evaluate the effect of repeated exposure (5 times for 15min) of 1800MHz radio-frequency radiation (RFR) on N-methyl-d-aspartate receptor subunit NR1 (NMDA-NR1) expression in the brains of rats in a persistent inflammatory state. We also measured the effect of RFR combined with tramadol (TRAM) to determine the potential antioxidant capacity of this agent. The effects of the Global System for Mobile Communication (GSM) modulated 1800MHz RFR exposure on the expression and activity of glutamate receptor channels with antioxidative activity in brain tissue was measured using oxygen radical absorbance capacity (ORAC) and electron spin resonance (ESR) detection of the hydroxyl radical generated by the Fenton reaction. NMDA-NR1 was measured in the cerebral tissue of rats with inflammation (complete Freund's adjuvent) and those injected with tramadol after RFR exposure (RFR, RFR/TRAM) and in non-exposed (baseline, TRAM) rats. No differences between the baseline group and the exposed group (RFR) were observed. NMDA-NR1 expression decreased after CFA injection and RFR exposure, and an elevated expression of NMDA-NR1 was observed in healthy control rats of both groups: TRAM/RFR and RFR. ORAC assessment revealed a robust effect of RFR, however the other experiments revealed equivocal effects. Further studies examining the combination of ORAC with NMDA are warranted to elucidate more clearly the effect of RFR on the brain. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  6. NMDA receptor activation upstream of methyl farnesoate signaling for short day-induced male offspring production in the water flea, Daphnia pulex.

    PubMed

    Toyota, Kenji; Miyakawa, Hitoshi; Yamaguchi, Katsushi; Shigenobu, Shuji; Ogino, Yukiko; Tatarazako, Norihisa; Miyagawa, Shinichi; Iguchi, Taisen

    2015-03-14

    The cladoceran crustacean Daphnia pulex produces female offspring by parthenogenesis under favorable conditions, but in response to various unfavorable external stimuli, it produces male offspring (environmental sex determination: ESD). We recently established an innovative system for ESD studies using D. pulex WTN6 strain, in which the sex of the offspring can be controlled simply by changes in the photoperiod: the long-day and short-day conditions can induce female and male offspring, respectively. Taking advantage of this system, we demonstrated that de novo methyl farnesoate (MF) synthesis is necessary for male offspring production. These results indicate the key role of innate MF signaling as a conductor between external environmental stimuli and the endogenous male developmental pathway. Despite these findings, the molecular mechanisms underlying up- and downstream signaling of MF have not yet been well elucidated in D. pulex. To elucidate up- and downstream events of MF signaling during sex determination processes, we compared the transcriptomes of daphnids reared under the long-day (female) condition with short-day (male) and MF-treated (male) conditions. We found that genes involved in ionotropic glutamate receptors, known to mediate the vast majority of excitatory neurotransmitting processes in various organisms, were significantly activated in daphnids by the short-day condition but not by MF treatment. Administration of specific agonists and antagonists, especially for the N-methyl-D-aspartic acid (NMDA) receptor, strongly increased or decreased, respectively, the proportion of male-producing mothers. Moreover, we also identified genes responsible for male production (e.g., protein kinase C pathway-related genes). Such genes were generally shared between the short-day reared and MF-treated daphnids. We identified several candidate genes regulating ESD which strongly suggests that these genes may be essential factors for male offspring production as an

  7. 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…

  8. Creatine affords protection against glutamate-induced nitrosative and oxidative stress.

    PubMed

    Cunha, Mauricio P; Lieberknecht, Vicente; Ramos-Hryb, Ana Belén; Olescowicz, Gislaine; Ludka, Fabiana K; Tasca, Carla I; Gabilan, Nelson H; Rodrigues, Ana Lúcia S

    2016-05-01

    Creatine has been reported to exert beneficial effects in several neurodegenerative diseases in which glutamatergic excitotoxicity and oxidative stress play an etiological role. The purpose of this study was to investigate the protective effects of creatine, as compared to the N-Methyl-d-Aspartate (NMDA) receptor antagonist dizocilpine (MK-801), against glutamate or hydrogen peroxide (H2O2)-induced injury in human neuroblastoma SH-SY5Y cells. Exposure of cells to glutamate (60-80 mM) or H2O2 (200-300 μM) for 24 h decreased cellular viability and increased dichlorofluorescein (DCF) fluorescence (indicative of increased reactive oxygen species, ROS) and nitric oxide (NO) production (assessed by mono-nitrogen oxides, NOx, levels). Creatine (1-10 mM) or MK-801 (0.1-10 μM) reduced glutamate- and H2O2-induced toxicity. The protective effect of creatine against glutamate-induced toxicity involves its antioxidant effect, since creatine, similar to MK-801, prevented the increase on DCF fluorescence induced by glutamate or H2O2. Furthermore, creatine or MK-801 blocked glutamate- and H2O2-induced increases in NOx levels. In another set of experiments, the repeated, but not acute, administration of creatine (300 mg/kg, po) in mice prevented the decreases on cellular viability and mitochondrial membrane potential (assessed by tetramethylrhodamine ethyl ester, TMRE, probe) of hippocampal slices incubated with glutamate (10 mM). Creatine concentration-dependent decreased the amount of nitrite formed in the reaction of oxygen with NO produced from sodium nitroprusside solution, suggesting that its protective effect against glutamate or H2O2-induced toxicity might be due to its scavenger activity. Overall, the results suggest that creatine may be useful as adjuvant therapy for neurodegenerative disease treatments. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Crucial Role of Postsynaptic Syntaxin 4 in Mediating Basal Neurotransmission and Synaptic Plasticity in Hippocampal CA1 Neurons.

    PubMed

    Bin, Na-Ryum; Ma, Ke; Harada, Hidekiyo; Tien, Chi-Wei; Bergin, Fiona; Sugita, Kyoko; Luyben, Thomas T; Narimatsu, Masahiro; Jia, Zhengping; Wrana, Jeffrey L; Monnier, Philippe P; Zhang, Liang; Okamoto, Kenichi; Sugita, Shuzo

    2018-06-05

    Trafficking of neurotransmitter receptors on postsynaptic membranes is critical for basal neurotransmission and synaptic plasticity, yet the underlying mechanisms remain elusive. Here, we investigated the role of syntaxin 4 in postsynaptic hippocampal CA1 neurons by analyzing conditional knockout (syntaxin 4 cKO) mice. We show that syntaxin 4 cKO resulted in reduction of basal neurotransmission without changes in paired-pulse ratios. Both α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and N-methyl-d-aspartic acid (NMDA) receptor-mediated charge transfers were diminished. Patch-clamp experiments revealed that amplitudes, but not frequencies, of spontaneous excitatory postsynaptic currents are reduced. Syntaxin 4 knockout (KO) caused drastic reduction in expression of surface α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and N-methyl-d-aspartic acid (NMDA) receptors in cultured hippocampal neurons. Furthermore, cKO caused defects in theta-burst stimulation induced long-term potentiation and spatial learning as assessed by a water maze task, indicating that synaptic plasticity was altered. Our data reveal a crucial role of syntaxin 4 in trafficking of ionotropic glutamate receptors that are essential for basal neurotransmission, synaptic plasticity, and spatial memory. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

  10. New Targets for Rapid Antidepressant Action

    PubMed Central

    Machado-Vieira, Rodrigo; Henter, Ioline D; Zarate, Carlos A.

    2016-01-01

    Current therapeutic options for major depressive disorder (MDD) and bipolar disorder (BD) are associated with a lag of onset that can prolong distress and impairment for patients, and their antidepressant efficacy is often limited. All currently approved antidepressant medications for MDD act primarily through monoaminergic mechanisms. Glutamate is the major excitatory neurotransmitter in the central nervous system, and glutamate and its cognate receptors are implicated in the pathophysiology of MDD, and in the development of novel therapeutics for this disorder. The rapid and robust antidepressant effects of the N-methyl-D-aspartate (NMDA) antagonist ketamine were first observed in 2000. Since then, other NMDA receptor antagonists have been studied in MDD. Most have demonstrated relatively modest antidepressant effects compared to ketamine, but some have shown more favorable characteristics. This article reviews the clinical evidence supporting the use of novel glutamate receptor modulators with direct affinity for cognate receptors: 1) non-competitive NMDA receptor antagonists (ketamine, memantine, dextromethorphan, AZD6765); 2) subunit (GluN2B)-specific NMDA receptor antagonists (CP-101,606/traxoprodil, MK-0657); 3) NMDA receptor glycine-site partial agonists (GLYX-13); and 4) metabotropic glutamate receptor (mGluR) modulators (AZD2066, RO4917523/basimglurant). We also briefly discuss several other theoretical glutamate receptor targets with preclinical antidepressant-like efficacy that have yet to be studied clinically; these include α-amino-3-hydroxyl-5-methyl-4-isoxazoleproprionic acid (AMPA) agonists and mGluR2/3 negative allosteric modulators. The review also discusses other promising, non-glutamatergic targets for potential rapid antidepressant effects, including the cholinergic system (scopolamine), the opioid system (ALKS-5461), corticotropin releasing factor (CRF) receptor antagonists (CP-316,311), and others. PMID:26724279

  11. H2O2 attenuates IGF-1R tyrosine phosphorylation and its survival signaling properties in neuronal cells via NR2B containing NMDA receptor.

    PubMed

    Zeng, Zhiwen; Wang, Dejun; Gaur, Uma; Rifang, Liao; Wang, Haitao; Zheng, Wenhua

    2017-09-12

    Impairment of insulin-like growth factor I (IGF-I) signaling plays an important role in the development of neurodegeneration. In the present study, we investigated the effect of H 2 O 2 on the survival signaling of IGF-1 and its underlying mechanisms in human neuronal cells SH-SY5Y. Our results showed that IGF-1 promoted cell survival and stimulated phosphorylation of IGF-1R as well as its downstream targets like AKT and ERK1/2 in these cells. Meanwhile, these effects of IGF-1 were abolished by H 2 O 2 at 200μM concentration which did not cause any significant toxicity to cells itself in our experiments. Moreover, studies using various glutamate receptor subtype antagonists displayed that N-methyl-D -aspartate (NMDA) receptor antagonist dizocilpine maleate (MK-801) blocked the effects of H 2 O 2 , whereas other glutamate receptor subtype antagonists, such as non-NMDA receptor antagonist 6,7-dinitroquinoxaline-2,3-dione (DNQX), metabolic glutamate receptor antagonists LY341495 and CPCCOEt, had no effect. Further studies revealed that NR2B-containing NMDARs are responsible for these effects as its effects were blocked by pharmacological inhibitor Ro25-698 or specific siRNA for NR2B, but not NR2A. Finally, our data also showed that Ca 2+ influx contributes to the effects of H 2 O 2 . Similar results were obtained in primary cultured cortical neurons. Taken together, the results from the present study suggested that H 2 O 2 attenuated IGF-1R tyrosine phosphorylation and its survival signaling properties via NR2B containing NMDA receptors and Ca 2+ influx in SH-SY5Y cells. Therefore, NMDAR antagonists, especially NR2B-selective ones, combined with IGF-1 may serve as an alternative therapeutic agent for oxidative stress related neurodegenerative disease.

  12. 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.

  13. 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.

  14. Psychological effects of (S)-ketamine and N,N-dimethyltryptamine (DMT): a double-blind, cross-over study in healthy volunteers.

    PubMed

    Gouzoulis-Mayfrank, E; Heekeren, K; Neukirch, A; Stoll, M; Stock, C; Obradovic, M; Kovar, K-A

    2005-11-01

    Pharmacological challenges with hallucinogens are used as models for psychosis in experimental research. The state induced by glutamate antagonists such as phencyclidine (PCP) is often considered as a more appropriate model of psychosis than the state induced by serotonergic hallucinogens such as lysergic acid diethylamide (LSD), psilocybin and N,N-dimethyltryptamine (DMT). However, so far, the psychological profiles of the two types of hallucinogenic drugs have never been studied directly in an experimental within-subject design. Fifteen healthy volunteers were included in a double-blind, cross-over study with two doses of the serotonin 5-HT2A agonist DMT and the glutamate N-methyl-D-aspartate (NMDA) antagonist (S)-ketamine. Data are reported for nine subjects who completed both experimental days with both doses of the two drugs. The intensity of global psychological effects was similar for DMT and (S)-ketamine. However, phenomena resembling positive symptoms of schizophrenia, particularly positive formal thought disorder and inappropriate affect, were stronger after DMT. Phenomena resembling negative symptoms of schizophrenia, attention deficits, body perception disturbances and catatonia-like motor phenomena were stronger after (S)-ketamine. The present study suggests that the NMDA antagonist model of psychosis is not overall superior to the serotonin 5-HT2A agonist model. Rather, the two classes of drugs tend to model different aspects or types of schizophrenia. The NMDA antagonist state may be an appropriate model for psychoses with prominent negative and possibly also catatonic features, while the 5-HT2A agonist state may be a better model for psychoses of the paranoid type.

  15. Alterations in NMDA receptor expression during retinal degeneration in the RCS rat.

    PubMed

    Gründer, T; Kohler, K; Guenther, E

    2001-01-01

    To determine how a progressive loss of photoreceptor cells and the concomitant loss of glutamatergic input to second-order neurons can affect inner-retinal signaling, glutamate receptor expression was analyzed in the Royal College of Surgeons (RCS) rat, an animal model of retinitis pigmentosa. Immunohistochemistry was performed on retinal sections of RCS rats and congenic controls between postnatal (P) day 3 and the aged adult (up to P350) using specific antibodies against N-methyl-D-aspartate (NMDA) subunits. All NMDA subunits (NR1, NR2A-2D) were expressed in control and dystrophic retinas at all ages, and distinct patterns of labeling were found in horizontal cells, subpopulations of amacrine cells and ganglion cells, as well as in the outer and inner plexiform layer (IPL). NRI immunoreactivity in the inner plexiform layer of adult control retinas was concentrated in two distinct bands, indicating a synaptic localization of NMDA receptors in the OFF and ON signal pathways. In the RCS retina, these bands of NRI immunoreactivity in the IPL were much weaker in animals older than P40. In parallel, NR2B immunoreactivity in the outer plexiform layer (OPL) of RCS rats was always reduced compared to controls and vanished between P40 and P120. The most striking alteration observed in the degenerating retina, however, was a strong expression of NRI immunoreactivity in Müller cell processes in the inner retina which was not observed in control animals and which was present prior to any visible sign of photoreceptor degeneration. The results suggest functional changes in glutamatergic receptor signaling in the dystrophic retina and a possible involvement of Müller cells in early processes of this disease.

  16. Brain glutamine synthesis requires neuronal-born aspartate as amino donor for glial glutamate formation.

    PubMed

    Pardo, Beatriz; Rodrigues, Tiago B; Contreras, Laura; Garzón, Miguel; Llorente-Folch, Irene; Kobayashi, Keiko; Saheki, Takeyori; Cerdan, Sebastian; Satrústegui, Jorgina

    2011-01-01

    The glutamate-glutamine cycle faces a drain of glutamate by oxidation, which is balanced by the anaplerotic synthesis of glutamate and glutamine in astrocytes. De novo synthesis of glutamate by astrocytes requires an amino group whose origin is unknown. The deficiency in Aralar/AGC1, the main mitochondrial carrier for aspartate-glutamate expressed in brain, results in a drastic fall in brain glutamine production but a modest decrease in brain glutamate levels, which is not due to decreases in neuronal or synaptosomal glutamate content. In vivo (13)C nuclear magnetic resonance labeling with (13)C(2)acetate or (1-(13)C) glucose showed that the drop in brain glutamine is due to a failure in glial glutamate synthesis. Aralar deficiency induces a decrease in aspartate content, an increase in lactate production, and lactate-to-pyruvate ratio in cultured neurons but not in cultured astrocytes, indicating that Aralar is only functional in neurons. We find that aspartate, but not other amino acids, increases glutamate synthesis in both control and aralar-deficient astrocytes, mainly by serving as amino donor. These findings suggest the existence of a neuron-to-astrocyte aspartate transcellular pathway required for astrocyte glutamate synthesis and subsequent glutamine formation. This pathway may provide a mechanism to transfer neuronal-born redox equivalents to mitochondria in astrocytes.

  17. Dizocilpine (MK-801) induces distinct changes of N-methyl-D-aspartic acid receptor subunits in parvalbumin-containing interneurons in young adult rat prefrontal cortex.

    PubMed

    Xi, Dong; Zhang, Wentong; Wang, Huai-Xing; Stradtman, George G; Gao, Wen-Jun

    2009-11-01

    N-methyl-D-aspartic acid receptor (NMDAR) hypofunction has long been implicated in schizophrenia and NMDARs on gamma-aminobutyric acid (GABA)ergic interneurons are proposed to play an essential role in the pathogenesis. However, controversial results have been reported regarding the regulation of NMDAR expression, and direct evidence of how NMDAR antagonists act on specific subpopulations of prefrontal interneurons is missing. We investigated the effects of the NMDAR antagonist dizocilpine (MK-801) on the expression of NMDAR subtypes in the identified interneurons in young adult rat prefrontal cortex (PFC) by using laser microdissection and real-time polymerase chain reaction, combined with Western blotting and immunofluorescent staining. We found that MK-801 induced distinct changes of NMDAR subunits in the parvalbumin-immunoreactive (PV-ir) interneurons vs. pyramidal neurons in the PFC circuitry. The messenger RNA (mRNA) expression of all NMDAR subtypes, including NR1 and NR2A to 2D, exhibited inverted-U dose-dependent changes in response to MK-801 treatment in the PFC. In contrast, subunit mRNAs of NMDARs in PV-ir interneurons were significantly down-regulated at low doses, unaltered at medium doses, and significantly decreased again at high doses, suggesting a biphasic dose response to MK-801. The differential effects of MK-801 in mRNA expression of NMDAR subunits were consistent with the protein expression of NR2A and NR2B subunits revealed with Western blotting and double immunofluorescent staining. These results suggest that PV-containing interneurons in the PFC exhibit a distinct responsiveness to NMDAR antagonism and that NMDA antagonist can differentially and dose-dependently regulate the functions of pyramidal neurons and GABAergic interneurons in the prefrontal cortical circuitry.

  18. D-Cycloserine for Treatment Nonresponders with Obsessive-Compulsive Disorder: A Case Report

    ERIC Educational Resources Information Center

    Norberg, Melissa M.; Gilliam, Christina M.; Villavicencio, Anna; Pearlson, Godfrey D.; Tolin, David F.

    2012-01-01

    Despite being the most effective treatment available, as many as one third of patients who receive exposure and response prevention (ERP) for obsessive-compulsive disorder (OCD) do not initially respond to treatment. Recent research suggests that the n-methyl d-aspartate (NMDA) receptor partial agonist D-Cycloserine (DCS) may speed up the course…

  19. [Anti-NMDA receptor encephalitis: two paediatric cases].

    PubMed

    González-Toro, M Cristina; Jadraque-Rodríguez, Rocío; Sempere-Pérez, Ángela; Martínez-Pastor, Pedro; Jover-Cerdá, Jenaro; Gómez-Gosálvez, Francisco

    2013-12-01

    Encephalitis associated to anti-N-methyl D-aspartate (NMDA) receptor antibodies is an autoimmune neurological pathology that has been reported increasingly more frequently in the paediatric population in recent years. We report two cases from our own experience with similar clinical pictures. Case 1: a 5-year-old girl who began with clinical signs and symptoms of convulsions and altered consciousness, associated to movement disorders and regression of previously acquired abilities that developed into autism. Case 2: a 13-year-old girl who presented left-side hemiparesis, abnormal movements, conduct disorder and dysautonomia. In both cases positive anti-NMDA receptor antibodies were obtained in cerebrospinal fluid and they were diagnosed with anti-NMDA receptor encephalitis. In the first case, treatment was established with intravenous perfusion of corticoids and immunoglobulins, and rituximab also had to be associated. In the second case, treatment consisted in corticoids and immunoglobulins. Progress was favourable in both cases, with a slight language disorder as a sequela in the first case and a relapse in the second case, with full resolution. Anti-NMDA receptor encephalitis is a treatable disorder and early diagnosis and treatment are crucial, since this improves the prognosis and diminishes the chances of relapses.

  20. 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.

  1. IgE binding to peanut allergens is inhibited by combined D-aspartic and D-glutamic acids.

    PubMed

    Chung, Si-Yin; Reed, Shawndrika

    2015-01-01

    The objective of this study was to determine if D-amino acids (D-aas) bind and inhibit immunoglobulin E (IgE) binding to peanut allergens. D-aas such as D-Asp (aspartic acid), D-Glu (glutamic acid), combined D-[Asp/Glu] and others were each prepared in a cocktail of 9 other D-aas, along with L-amino acids (L-aas) and controls. Each sample was mixed with a pooled plasma from peanut-allergic donors, and tested by ELISA (enzyme-linked immunosorbent assay) and Western blots for IgE binding to peanut allergens. Results showed that D-[Asp/Glu] (4 mg/ml) inhibited IgE binding (75%) while D-Glu, D-Asp and other D-aas had no inhibitory effect. A higher inhibition was seen with D-[Asp/Glu] than with L-[Asp/Glu]. We concluded that IgE was specific for D-[Asp/Glu], not D-Asp or D-Glu, and that D-[Asp/Glu] was more reactive than was L-[Asp/Glu] in IgE inhibition. The finding indicates that D-[Asp/Glu] may have the potential for removing IgE or reducing IgE binding to peanut allergens in vitro. Published by Elsevier Ltd.

  2. 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.

  3. mGluR2/3 agonist LY379268 rescues NMDA and GABAA receptor level deficits induced in a two-hit mouse model of schizophrenia.

    PubMed

    Engel, Martin; Snikeris, Peta; Matosin, Natalie; Newell, Kelly Anne; Huang, Xu-Feng; Frank, Elisabeth

    2016-04-01

    An imbalance of excitatory and inhibitory neurotransmission underlies the glutamate hypothesis of schizophrenia. Agonists of group II metabotropic glutamate receptors, mGluR2/3, have been proposed as novel therapeutic agents to correct this imbalance. However, the influence of mGluR2/3 activity on excitatory and inhibitory neurotransmitter receptors has not been explored. We aimed to investigate the ability of a novel mGluR2/3 agonist, LY379268, to modulate the availability of the excitatory N-methyl-D-aspartate receptor (NMDA-R) and the inhibitory gamma-aminobutyrate-A receptor (GABAA-R), in a two-hit mouse model of schizophrenia. Wild type (WT) and heterozygous neuregulin 1 transmembrane domain mutant mice (NRG1 HET) were treated daily with phencyclidine (10 mg/kg ip) or saline for 14 days. After a 14-day washout, an acute dose of the mGluR2/3 agonist LY379268 (3 mg/kg), olanzapine (antipsychotic drug comparison, 1.5 mg/kg), or saline was administered. NMDA-R and GABAA-R binding densities were examined by receptor autoradiography in several schizophrenia-relevant brain regions. In both WT and NRG1 HET mice, phencyclidine treatment significantly reduced NMDA-R and GABAA-R binding density in the prefrontal cortex, hippocampus, and nucleus accumbens. Acute treatment with LY379268 restored NMDA-R and GABAA-R levels in the two-hit mouse model comparable to olanzapine. We demonstrate that the mGluR2/3 agonist LY379268 restores excitatory and inhibitory deficits with similar efficiency as olanzapine in our two-hit schizophrenia mouse model. This study significantly contributes to our understanding of the mechanisms underlying the therapeutic effects of LY379268 and supports the use of agents aimed at mGluR2/3.

  4. Quinolinic acid induces neuritogenesis in SH-SY5Y neuroblastoma cells independently of NMDA receptor activation.

    PubMed

    Hernandez-Martinez, Juan-Manuel; Forrest, Caroline M; Darlington, L Gail; Smith, Robert A; Stone, Trevor W

    2017-03-01

    Glutamate and nicotinamide adenine dinucleotide (NAD + ) have been implicated in neuronal development and several types of cancer. The kynurenine pathway of tryptophan metabolism includes quinolinic acid (QA) which is both a selective agonist at N-methyl-D-aspartate (NMDA) receptors and also a precursor for the formation of NAD + . The effect of QA on cell survival and differentiation has therefore been examined on SH-SY5Y human neuroblastoma cells. Retinoic acid (RA, 10 μm) induced differentiation of SH-SY5Y cells into a neuronal phenotype showing neurite growth. QA (50-150 nm) also caused a concentration-dependent increase in the neurite/soma ratio, indicating differentiation. Both RA and QA increased expression of the neuronal marker β3-tubulin in whole-cell homogenates and in the neuritic fraction assessed using a neurite outgrowth assay. Expression of the neuronal proliferation marker doublecortin revealed that, unlike RA, QA did not decrease the number of mitotic cells. QA-induced neuritogenesis coincided with an increase in the generation of reactive oxygen species. Neuritogenesis was prevented by diphenylene-iodonium (an inhibitor of NADPH oxidase) and superoxide dismutase, supporting the involvement of reactive oxygen species. NMDA itself did not promote neuritogenesis and the NMDA antagonist dizocilpine (MK-801) did not prevent quinolinate-induced neuritogenesis, indicating that the effects of QA were independent of NMDA receptors. Nicotinamide caused a significant increase in the neurite/soma ratio and the expression of β3-tubulin in the neuritic fraction. Taken together, these results suggest that QA induces neuritogenesis by promoting oxidizing conditions and affecting the availability of NAD + , independently of NMDA receptors. © 2016 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  5. 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

  6. 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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. The PICK1 Ca2+ sensor modulates N-methyl-d-aspartate (NMDA) receptor-dependent microRNA-mediated translational repression in neurons.

    PubMed

    Rajgor, Dipen; Fiuza, Maria; Parkinson, Gabrielle T; Hanley, Jonathan G

    2017-06-09

    MicroRNAs (miRNAs) are important regulators of localized mRNA translation in neuronal dendrites. The presence of RNA-induced silencing complex proteins in these compartments and the dynamic miRNA expression changes that occur in response to neuronal stimulation highlight their importance in synaptic plasticity. Previously, we demonstrated a novel interaction between the major RNA-induced silencing complex component Argounaute-2 (Ago2) and the BAR (bin/amphiphysin/rvs) domain protein PICK1. PICK1 recruits Ago2 to recycling endosomes in dendrites, where it inhibits miRNA-mediated translational repression. Chemical induction of long-term depression via NMDA receptor activation causes the dissociation of Ago2 from PICK1 and a consequent increase in dendritic miRNA-mediated gene silencing. The mechanism that underlies the regulation of PICK1-Ago2 binding is unknown. In this study, we demonstrate that the PICK1-Ago2 interaction is directly sensitive to Ca 2+ ions so that high [Ca 2+ ] free reduces PICK1 binding to Ago2. Mutating a stretch of C-terminal Ca 2+ -binding residues in PICK1 results in a complete block of NMDA-induced PICK1-Ago2 disassociation in cortical neurons. Furthermore, the same mutant also blocks NMDA-stimulated miRNA-mediated gene silencing. This study defines a novel mechanism whereby elevated [Ca 2+ ] induced by NMDA receptor activation modulates Ago2 and miRNA activity via PICK1. Our work suggests a Ca 2+ -dependent process to regulate miRNA activity in neurons in response to the induction of long-term depression. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  8. On the Role of Glutamate in Presynaptic Development: Possible Contributions of Presynaptic NMDA Receptors.

    PubMed

    Fedder, Karlie N; Sabo, Shasta L

    2015-12-14

    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.

  9. Ion channels in EEG: isolating channel dysfunction in NMDA receptor antibody encephalitis.

    PubMed

    Symmonds, Mkael; Moran, Catherine H; Leite, M Isabel; Buckley, Camilla; Irani, Sarosh R; Stephan, Klaas Enno; Friston, Karl J; Moran, Rosalyn J

    2018-06-01

    See Roberts and Breakspear (doi:10.1093/brain/awy136) for a scientific commentary on this article.Neurological and psychiatric practice frequently lack diagnostic probes that can assess mechanisms of neuronal communication non-invasively in humans. In N-methyl-d-aspartate (NMDA) receptor antibody encephalitis, functional molecular assays are particularly important given the presence of NMDA antibodies in healthy populations, the multifarious symptomology and the lack of radiological signs. Recent advances in biophysical modelling techniques suggest that inferring cellular-level properties of neural circuits from macroscopic measures of brain activity is possible. Here, we estimated receptor function from EEG in patients with NMDA receptor antibody encephalitis (n = 29) as well as from encephalopathic and neurological patient controls (n = 36). We show that the autoimmune patients exhibit distinct fronto-parietal network changes from which ion channel estimates can be obtained using a microcircuit model. Specifically, a dynamic causal model of EEG data applied to spontaneous brain responses identifies a selective deficit in signalling at NMDA receptors in patients with NMDA receptor antibody encephalitis but not at other ionotropic receptors. Moreover, though these changes are observed across brain regions, these effects predominate at the NMDA receptors of excitatory neurons rather than at inhibitory interneurons. Given that EEG is a ubiquitously available clinical method, our findings suggest a unique re-purposing of EEG data as an assay of brain network dysfunction at the molecular level.

  10. Separate intramolecular targets for protein kinase A control N-methyl-D-aspartate receptor gating and Ca2+ permeability.

    PubMed

    Aman, Teresa K; Maki, Bruce A; Ruffino, Thomas J; Kasperek, Eileen M; Popescu, Gabriela K

    2014-07-04

    Protein kinase A (PKA) enhances synaptic plasticity in the central nervous system by increasing NMDA receptor current amplitude and Ca(2+) flux in an isoform-dependent yet poorly understood manner. PKA phosphorylates multiple residues on GluN1, GluN2A, and GluN2B subunits in vivo, but the functional significance of this multiplicity is unknown. We examined gating and permeation properties of recombinant NMDA receptor isoforms and of receptors with altered C-terminal domain (CTDs) prior to and after pharmacological inhibition of PKA. We found that PKA inhibition decreased GluN1/GluN2B but not GluN1/GluN2A gating; this effect was due to slower rates for receptor activation and resensitization and was mediated exclusively by the GluN2B CTD. In contrast, PKA inhibition reduced NMDA receptor-relative Ca(2+) permeability (PCa/PNa) regardless of the GluN2 isoform and required the GluN1 CTD; this effect was due primarily to decreased unitary Ca(2+) conductance, because neither Na(+) conductance nor Ca(2+)-dependent block was altered substantially. Finally, we show that both the gating and permeation effects can be reproduced by changing the phosphorylation state of a single residue: GluN2B Ser-1166 and GluN1 Ser-897, respectively. We conclude that PKA effects on NMDA receptor gating and Ca(2+) permeability rely on distinct phosphorylation sites located on the CTD of GluN2B and GluN1 subunits. This separate control of NMDA receptor properties by PKA may account for the specific effects of PKA on plasticity during synaptic development and may lead to drugs targeted to alter NMDA receptor gating or Ca(2+) permeability. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  11. Separate Intramolecular Targets for Protein Kinase A Control N-Methyl-d-aspartate Receptor Gating and Ca2+ Permeability*

    PubMed Central

    Aman, Teresa K.; Maki, Bruce A.; Ruffino, Thomas J.; Kasperek, Eileen M.; Popescu, Gabriela K.

    2014-01-01

    Protein kinase A (PKA) enhances synaptic plasticity in the central nervous system by increasing NMDA receptor current amplitude and Ca2+ flux in an isoform-dependent yet poorly understood manner. PKA phosphorylates multiple residues on GluN1, GluN2A, and GluN2B subunits in vivo, but the functional significance of this multiplicity is unknown. We examined gating and permeation properties of recombinant NMDA receptor isoforms and of receptors with altered C-terminal domain (CTDs) prior to and after pharmacological inhibition of PKA. We found that PKA inhibition decreased GluN1/GluN2B but not GluN1/GluN2A gating; this effect was due to slower rates for receptor activation and resensitization and was mediated exclusively by the GluN2B CTD. In contrast, PKA inhibition reduced NMDA receptor-relative Ca2+ permeability (PCa/PNa) regardless of the GluN2 isoform and required the GluN1 CTD; this effect was due primarily to decreased unitary Ca2+ conductance, because neither Na+ conductance nor Ca2+-dependent block was altered substantially. Finally, we show that both the gating and permeation effects can be reproduced by changing the phosphorylation state of a single residue: GluN2B Ser-1166 and GluN1 Ser-897, respectively. We conclude that PKA effects on NMDA receptor gating and Ca2+ permeability rely on distinct phosphorylation sites located on the CTD of GluN2B and GluN1 subunits. This separate control of NMDA receptor properties by PKA may account for the specific effects of PKA on plasticity during synaptic development and may lead to drugs targeted to alter NMDA receptor gating or Ca2+ permeability. PMID:24847051

  12. Role of AMPA and NMDA receptors and back-propagating action potentials in spike timing-dependent plasticity.

    PubMed

    Fuenzalida, Marco; Fernández de Sevilla, David; Couve, Alejandro; Buño, Washington

    2010-01-01

    The cellular mechanisms that mediate spike timing-dependent plasticity (STDP) are largely unknown. We studied in vitro in CA1 pyramidal neurons the contribution of AMPA and N-methyl-d-aspartate (NMDA) components of Schaffer collateral (SC) excitatory postsynaptic potentials (EPSPs; EPSP(AMPA) and EPSP(NMDA)) and of the back-propagating action potential (BAP) to the long-term potentiation (LTP) induced by a STDP protocol that consisted in pairing an EPSP and a BAP. Transient blockade of EPSP(AMPA) with 7-nitro-2,3-dioxo-1,4-dihydroquinoxaline-6-carbonitrile (CNQX) during the STDP protocol prevented LTP. Contrastingly LTP was induced under transient inhibition of EPSP(AMPA) by combining SC stimulation, an imposed EPSP(AMPA)-like depolarization, and BAP or by coupling the EPSP(NMDA) evoked under sustained depolarization (approximately -40 mV) and BAP. In Mg(2+)-free solution EPSP(NMDA) and BAP also produced LTP. Suppression of EPSP(NMDA) or BAP always prevented LTP. Thus activation of NMDA receptors and BAPs are needed but not sufficient because AMPA receptor activation is also obligatory for STDP. However, a transient depolarization of another origin that unblocks NMDA receptors and a BAP may also trigger LTP.

  13. New targets for rapid antidepressant action.

    PubMed

    Machado-Vieira, Rodrigo; Henter, Ioline D; Zarate, Carlos A

    2017-05-01

    Current therapeutic options for major depressive disorder (MDD) and bipolar disorder (BD) are associated with a lag of onset that can prolong distress and impairment for patients, and their antidepressant efficacy is often limited. All currently approved antidepressant medications for MDD act primarily through monoaminergic mechanisms. Glutamate is the major excitatory neurotransmitter in the central nervous system, and glutamate and its cognate receptors are implicated in the pathophysiology of MDD, and in the development of novel therapeutics for this disorder. The rapid and robust antidepressant effects of the N-methyl-d-aspartate (NMDA) antagonist ketamine were first observed in 2000. Since then, other NMDA receptor antagonists have been studied in MDD. Most have demonstrated relatively modest antidepressant effects compared to ketamine, but some have shown more favorable characteristics. This article reviews the clinical evidence supporting the use of novel glutamate receptor modulators with direct affinity for cognate receptors: (1) non-competitive NMDA receptor antagonists (ketamine, memantine, dextromethorphan, AZD6765); (2) subunit (GluN2B)-specific NMDA receptor antagonists (CP-101,606/traxoprodil, MK-0657); (3) NMDA receptor glycine-site partial agonists (GLYX-13); and (4) metabotropic glutamate receptor (mGluR) modulators (AZD2066, RO4917523/basimglurant). We also briefly discuss several other theoretical glutamate receptor targets with preclinical antidepressant-like efficacy that have yet to be studied clinically; these include α-amino-3-hydroxyl-5-methyl-4-isoxazoleproprionic acid (AMPA) agonists and mGluR2/3 negative allosteric modulators. The review also discusses other promising, non-glutamatergic targets for potential rapid antidepressant effects, including the cholinergic system (scopolamine), the opioid system (ALKS-5461), corticotropin releasing factor (CRF) receptor antagonists (CP-316,311), and others. Published by Elsevier Ltd.

  14. The plasticity of the association between mu-opioid receptor and glutamate ionotropic receptor N in opioid analgesic tolerance and neuropathic pain.

    PubMed

    Sánchez-Blázquez, Pilar; Rodríguez-Muñoz, Maria; Berrocoso, Esther; Garzón, Javier

    2013-09-15

    Multiple groups have reported the functional cross-regulation between mu-opioid (MOP) receptor and glutamate ionotropic receptor N (GluN), and the post-synaptic association of these receptors has been implicated in the transmission and modulation of nociceptive signals. Opioids, such as morphine, disrupt the MOP receptor-GluN receptor complex to stimulate the activity of GluN receptors via protein kinase C (PKC)/Src. This increased GluN receptor activity opposes MOP receptor signalling, and via neural nitric oxide synthase (nNOS) and calcium and calmodulin regulated kinase II (CaMKII) induces the phosphorylation and uncoupling of the opioid receptor, which results in the development of morphine analgesic tolerance. Both experimental in vivo activation of GluN receptors and neuropathic pain separate the MOP receptor-GluN receptor complex via protein kinase A (PKA) and reduce the analgesic capacity of morphine. The histidine triad nucleotide-binding protein 1 (HINT1) associates with the MOP receptor C-terminus and connects the activities of MOP receptor and GluN receptor. In HINT1⁻/⁻ mice, morphine promotes enhanced analgesia and produces tolerance that is not related to GluN receptor activity. In these mice, the GluN receptor agonist N-methyl-D-aspartate acid (NMDA) does not antagonise the analgesic effects of morphine. Treatments that rescue morphine from analgesic tolerance, such as GluN receptor antagonism or PKC, nNOS and CaMKII inhibitors, all induce MOP receptor-GluN receptor re-association and reduce GluN receptor/CaMKII activity. In mice treated with NMDA or suffering from neuropathic pain (induced by chronic constriction injury, CCI), GluN receptor antagonists, PKA inhibitors or certain antidepressants also diminish CaMKII activity and restore the MOP receptor-GluN receptor association. Thus, the HINT1 protein stabilises the association between MOP receptor and GluN receptor, necessary for the analgesic efficacy of morphine, and this coupling is reduced

  15. NMDA Receptor Antagonism Impairs Reversal Learning in Developing Rats

    PubMed Central

    Chadman, Kathryn K.; Watson, Deborah J.; Stanton, Mark E.

    2014-01-01

    Four experiments examined the effect of dizocilpine maleate (MK-801), a noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist, on reversal learning during development. On postnatal days (PND) 21, 26, or 30, rats were trained on spatial discrimination and reversal in a T-maze. When MK-801 was administered (intraperitoneally) before both acquisition and reversal, 0.18 mg/kg generally impaired performance, whereas doses of 0.06 mg/kg and 0.10 mg/kg, but not 0.03 mg/kg, selectively impaired reversal learning (Experiments 1 and 3). The selective effect on reversal was not a result of sensitization to the second dose of MK-801 (Experiment 2) and was observed when the drug was administered only during reversal in an experiment addressing state-dependent learning (Experiment 4). Spatial reversal learning is more sensitive to NMDA-receptor antagonism than is acquisition. No age differences in sensitivity to MK-801 were found between PND 21 and 30. PMID:17014258

  16. CYP3A4 and CYP3A5 catalyse the conversion of the N-methyl-D-aspartate (NMDA) antagonist CJ-036878 to two novel dimers.

    PubMed

    Emoto, C; Nishida, H; Hirai, H; Iwasaki, K

    2007-12-01

    CJ-036878, N-(3-phenethoxybenzyl)-4-hydroxybenzamide, was developed as an antagonist of the N-methyl-D-aspartate receptor NR2B subunit. Two dimeric metabolites, CJ-047710 and CJ-047713, were identified from the incubation mixture with CJ-036878 in human liver microsomes (HLM). The identification of the enzymes involved in the formation of these dimeric metabolites was investigated in the current study. Inhibition of the formation of CJ-047710 and CJ-047713 in pooled HLM by 1-aminobenztriazole, SKF-525A, and ketoconazole were observed. Ketoconazole played a significant role in inhibiting formation of these two metabolites in a concentration-dependent manner. Recombinant CYP3A4 and CYP3A5 exhibited a markedly high activity toward the formation of CJ-047710 and CJ-047713 from CJ-036878, but the contribution of other CYP enzymes to these formations was at a very low level or negligible. The formation of CJ-047710 and CJ-047713 in pooled HLM, CYP3A4, and CYP3A5 showed sigmoid characteristics. S50 values for CJ-047710 and CJ-047713 formation in HLM were almost equivalent with those for CYP3A4 and CYP3A5. For the CYP3A enzymes, maximal clearance due to auto-activation values for CJ-047710 and CJ-047713 formation catalysed by CYP3A5 were 3.6- and 3.1-fold higher than those catalysed by CYP3A4. This is the first report that shows both CYP3A4 and CYP3A5 simultaneously contribute to dimerization through oxidative C-C and C-O coupling reactions.

  17. Loss of GluN2D subunit results in social recognition deficit, social stress, 5-HT2C receptor dysfunction, and anhedonia in mice.

    PubMed

    Yamamoto, Hideko; Kamegaya, Etsuko; Hagino, Yoko; Takamatsu, Yukio; Sawada, Wakako; Matsuzawa, Maaya; Ide, Soichiro; Yamamoto, Toshifumi; Mishina, Masayoshi; Ikeda, Kazutaka

    2017-01-01

    The N-methyl-d-aspartate (NMDA) receptor channel is involved in various physiological functions, including learning and memory. The GluN2D subunit of the NMDA receptor has low expression in the mature brain, and its role is not fully understood. In the present study, the effects of GluN2D subunit deficiency on emotional and cognitive function were investigated in GluN2D knockout (KO) mice. We found a reduction of motility (i.e., a depressive-like state) in the tail suspension test and a reduction of sucrose preference (i.e., an anhedonic state) in GluN2D KO mice that were group-housed with littermates. Despite apparently normal olfactory function and social interaction, GluN2D KO mice exhibited a decrease in preference for social novelty, suggesting a deficit in social recognition or memory. Golgi-Cox staining revealed a reduction of the complexity of dendritic trees in the accessory olfactory bulb in GluN2D KO mice, suggesting a deficit in pheromone processing pathway activation, which modulates social recognition. The deficit in social recognition may result in social stress in GluN2D KO mice. Isolation housing is a procedure that has been shown to reduce stress in mice. Interestingly, 3-week isolation and treatment with agomelatine or the 5-hydroxytryptamine-2C (5-HT 2C ) receptor antagonist SB242084 reversed the anhedonic-like state in GluN2D KO mice. In contrast, treatment with the 5-HT 2C receptor agonist CP809101 induced depressive- and anhedonic-like states in isolated GluN2D KO mice. These results suggest that social stress that is caused by a deficit in social recognition desensitizes 5-HT 2c receptors, followed by an anhedonic- and depressive-like state, in GluN2D KO mice. The GluN2D subunit of the NMDA receptor appears to be important for the recognition of individuals and development of normal emotionality in mice. 5-HT 2C receptor antagonism may be a therapeutic target for treating social stress-induced anhedonia. This article is part of the Special

  18. 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'. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  19. Interactions of Pannexin1 channels with purinergic and NMDA receptor channels.

    PubMed

    Li, Shuo; Bjelobaba, Ivana; Stojilkovic, Stanko S

    2018-01-01

    Pannexins are a three-member family of vertebrate plasma membrane spanning molecules that have homology to the invertebrate gap junction forming proteins, the innexins. However, pannexins do not form gap junctions but operate as plasma membrane channels. The best-characterized member of these proteins, Pannexin1 (Panx1) was suggested to be functionally associated with purinergic P2X and N-methyl-D-aspartate (NMDA) receptor channels. Activation of these receptor channels by their endogenous ligands leads to cross-activation of Panx1 channels. This in turn potentiates P2X and NMDA receptor channel signaling. Two potentiation concepts have been suggested: enhancement of the current responses and/or sustained receptor channel activation by ATP released through Panx1 pore and adenosine generated by ectonucleotidase-dependent dephosphorylation of ATP. Here we summarize the current knowledge and hypotheses about interactions of Panx1 channels with P2X and NMDA receptor channels. This article is part of a Special Issue entitled: Gap Junction Proteins edited by Jean Claude Herve. Published by Elsevier B.V.

  20. An in vivo evaluation of the antiseizure activity and acute neurotoxicity of agmatine.

    PubMed

    Bence, Aimee K; Worthen, David R; Stables, James P; Crooks, Peter A

    2003-02-01

    Agmatine, an endogenous cationic amine, exerts a wide range of biological effects, including modulation of glutamate-activated N-methyl-D-aspartate (NMDA) receptor function in the central nervous system (CNS). Since glutamate and the NMDA receptor have been implicated in the initiation and spread of seizure activity, the capacity of agmatine to inhibit seizure spread was evaluated in vivo. Orally administered agmatine (30 mg/kg) protected against maximal electroshock seizure (MES)-induced seizure spread in rats as rapidly as 15 min and for as long as 6 h after administration. Inhibition of MES-induced seizure spread was also observed when agmatine was administered intraperitoneally. Agmatine's antiseizure activity did not appear to be dose-dependent. An in vivo neurotoxicity screen indicated that agmatine was devoid of any acute neurological toxicity at the doses tested. These preliminary data suggest that agmatine has promising anticonvulsant activity.

  1. Antinociceptive actions of honokiol and magnolol on glutamatergic and inflammatory pain

    PubMed Central

    2009-01-01

    The antinociceptive effects of honokiol and magnolol, two major bioactive constituents of the bark of Magnolia officinalis, were investigated on animal paw licking responses and thermal hyperalgesia induced by glutamate receptor agonists including glutamate, N-methyl-D-aspartate (NMDA), and metabotropic glutamate 5 receptor (mGluR5) activator (RS)-2-chloro-5-hydroxyphenylglycine (CHPG), as well as inflammatory mediators such as substance P and prostaglandin E2 (PGE2) in mice. The actions of honokiol and magnolol on glutamate-induced c-Fos expression in the spinal cord dorsal horn were also examined. Our data showed that honokiol and magnolol blocked glutamate-, substance P- and PGE2-induced inflammatory pain with similar potency and efficacy. Consistently, honokiol and magnolol significantly decreased glutamate-induced c-Fos protein expression in superficial (I-II) laminae of the L4-L5 lumbar dorsal horn. However, honokiol was more selective than magnolol for inhibition of NMDA-induced licking behavioral and thermal hyperalgesia. In contrast, magnolol was more potent to block CHPG-mediated thermal hyperalgesia. These results demonstrate that honokiol and magnolol effectively decreased the inflammatory pain. Furthermore, their different potency on inhibition of nociception provoked by NMDA receptor and mGluR5 activation should be considered. PMID:19832997

  2. Thalamocortical NMDA conductances and intracortical inhibition can explain cortical temporal tuning

    NASA Technical Reports Server (NTRS)

    Krukowski, A. E.; Miller, K. D.

    2001-01-01

    Cells in cerebral cortex fail to respond to fast-moving stimuli that evoke strong responses in the thalamic nuclei innervating the cortex. The reason for this behavior has remained a mystery. We study an experimentally motivated model of the thalamic input-recipient layer of cat primary visual cortex that accounts for many aspects of cortical orientation tuning. In this circuit, inhibition dominates over excitation, but temporal modulations of excitation and inhibition occur out of phase with one another, allowing excitation to transiently drive cells. We show that this circuit provides a natural explanation of cortical low-pass temporal frequency tuning, provided N-methyl-D-aspartate (NMDA) receptors are present in thalamocortical synapses in proportions measured experimentally. This suggests a new and unanticipated role for NMDA conductances in shaping the temporal response properties of cortical cells, and suggests that common cortical circuit mechanisms underlie both spatial and temporal response tuning.

  3. Increased serum anti-N-methyl-D-aspartate receptor antibody immunofluorescence in psychiatric patients with past catatonia

    PubMed Central

    Lin, Chin-Chuen; Hung, Yi-Yung; Tsai, Meng-Chang

    2017-01-01

    Objective Anti-N-methyl-D-aspartate receptor (NMDAR) antibody was thought to be the cause of anti-NMDAR encephalitis, with manifestations similar to catatonia and schizophrenia. Anti-NMDAR antibody in neuropsychiatric patients who had catatonia before were investigated in a follow-up evaluation. The intensity of antibody immunofluorescence was quantified and compared with healthy controls. Method Nineteen patients (eight males and eleven females) agreed to be followed-up. Thirteen had the diagnosis of schizophrenia, two had the diagnosis of major depressive disorder, two had bipolar disorder, one had postpartum depression, and one had herpes simplex encephalitis. No patient had catatonia during the follow-up. Nineteen sex-matched healthy controls were recruited. Results Using Mann-Whitney U test, patients had greater intensity of anti-NMDAR antibody immunofluorescence than the healthy controls (121,979 ± 86,526 vs. 47,692 ± 26,102, p = 0.003). No correlation was found between immunofluorescence intensity and catatonia scales or symptom severity scores. Neuropsychiatric patients with past catatonia showed greater anti-NMDAR antibody response than the healthy controls. Conclusion NMDAR dysfunction might play a role in the mechanism underlying catatonia. Further studies are needed to confirm this finding. PMID:29073246

  4. Increased serum anti-N-methyl-D-aspartate receptor antibody immunofluorescence in psychiatric patients with past catatonia.

    PubMed

    Lin, Chin-Chuen; Hung, Yi-Yung; Tsai, Meng-Chang; Huang, Tiao-Lai

    2017-01-01

    Anti-N-methyl-D-aspartate receptor (NMDAR) antibody was thought to be the cause of anti-NMDAR encephalitis, with manifestations similar to catatonia and schizophrenia. Anti-NMDAR antibody in neuropsychiatric patients who had catatonia before were investigated in a follow-up evaluation. The intensity of antibody immunofluorescence was quantified and compared with healthy controls. Nineteen patients (eight males and eleven females) agreed to be followed-up. Thirteen had the diagnosis of schizophrenia, two had the diagnosis of major depressive disorder, two had bipolar disorder, one had postpartum depression, and one had herpes simplex encephalitis. No patient had catatonia during the follow-up. Nineteen sex-matched healthy controls were recruited. Using Mann-Whitney U test, patients had greater intensity of anti-NMDAR antibody immunofluorescence than the healthy controls (121,979 ± 86,526 vs. 47,692 ± 26,102, p = 0.003). No correlation was found between immunofluorescence intensity and catatonia scales or symptom severity scores. Neuropsychiatric patients with past catatonia showed greater anti-NMDAR antibody response than the healthy controls. NMDAR dysfunction might play a role in the mechanism underlying catatonia. Further studies are needed to confirm this finding.

  5. Activation of µ-opioid receptors and block of KIR3 potassium channels and NMDA receptor conductance by l- and d-methadone in rat locus coeruleus

    PubMed Central

    Matsui, Aya; Williams, John T

    2010-01-01

    BACKGROUND AND PURPOSE Methadone activates opioid receptors to increase a potassium conductance mediated by G-protein-coupled, inwardly rectifying, potassium (KIR3) channels. Methadone also blocks KIR3 channels and N-methyl-D-aspartic acid (NMDA) receptors. However, the concentration dependence and stereospecificity of receptor activation and channel blockade by methadone on single neurons has not been characterized. EXPERIMENTAL APPROACH Intracellular and whole-cell recording were made from locus coeruleus neurons in brain slices and the activation of µ-opioid receptors and blockade of KIR3 and NMDA channels with l- and d-methadone was examined. KEY RESULTS The potency of l-methadone, measured by the amplitude of hyperpolarization was 16.5-fold higher than with d-methadone. A maximum hyperpolarization was caused by both enantiomers (∼30 mV); however, the maximum outward current measured with whole-cell voltage-clamp recording was smaller than the current induced by [Met]5enkephalin. The KIR3 conductance induced by activation of α2-adrenoceptors was decreased with high concentrations of l- and d-methadone (10–30 µM). In addition, methadone blocked the resting inward rectifying conductance (KIR). Both l- and d-methadone blocked the NMDA receptor-dependent current. The block of NMDA receptor-dependent current was voltage-dependent suggesting that methadone acted as a channel blocker. CONCLUSIONS AND IMPLICATIONS Methadone activated µ-opioid receptors at low concentrations in a stereospecific manner. KIR3 and NMDA receptor channel block was not stereospecific and required substantially higher concentrations. The separation in the concentration range suggests that the activation of µ-opioid receptors rather than the channel blocking properties mediate both the therapeutic and toxic actions of methadone. PMID:20659105

  6. Effects of Acutely Elevated Hydrostatic Pressure in a Rat Ex Vivo Retinal Preparation

    PubMed Central

    Yoshitomi, Takeshi; Zorumski, Charles F.; Izumi, Yukitoshi

    2010-01-01

    Purpose. A new experimental glaucoma model was developed by using an ex vivo rat retinal preparation to examine the effects of elevated hydrostatic pressure on retinal morphology and glutamine synthetase (GS) activity. Methods. Ex vivo rat retinas were exposed to elevated hydrostatic pressure for 24 hours in the presence of glutamate or glutamate receptor antagonists and examined histologically. GS activity was assessed by colorimetric assay. Results. Pressure elevation induced axonal swelling in the nerve fiber layer. Axonal swelling was prevented by a combination of non-N-methyl-d-aspartate (non-NMDA) receptor antagonist and an NMDA receptor antagonist, indicating that the damage results from activation of both types of glutamate receptor. When glial function was preserved, the typical changes induced by glutamate consisted of reversible Müller cell swelling resulting from excessive glial glutamate uptake. The irreversible Müller cell swelling in hyperbaric conditions may indicate that pressure disrupts glutamate metabolism. Indeed, elevated pressure inhibited GS activity. In addition, glutamate exposure after termination of pressure exposure exhibited apparent Müller cell swelling. Conclusions. These results suggest that the neural degeneration observed during pressure elevation is caused by impaired glial glutamate metabolism after uptake. PMID:20688725

  7. NMDA Receptors as Potential Therapeutic Targets in Diabetic Nephropathy: Increased Renal NMDA Receptor Subunit Expression in Akita Mice and Reduced Nephropathy Following Sustained Treatment With Memantine or MK-801.

    PubMed

    Roshanravan, Hila; Kim, Eun Young; Dryer, Stuart E

    2016-10-01

    N-methyl-d-aspartate (NMDA) receptors are expressed throughout the kidney, and the abundance of these receptors and some of their endogenous agonists are increased in diabetes. Moreover, sustained activation of podocyte NMDA receptors induces Ca(2+) influx, oxidative stress, loss of slit diaphragm proteins, and apoptosis. We observed that NMDA receptor subunits and their transcripts are increased in podocytes and mesangial cells cultured in elevated glucose compared with controls. A similar increase in NMDA subunits, especially NR1, NR2A, and NR2C, was observed in glomeruli and tubules of Akita mice. Sustained continuous treatment with the strong NMDA receptor antagonist dizocilpine (MK-801) for 28 days starting at 8 weeks of age reduced 24-h albumin excretion and mesangial matrix expansion and improved glomerular ultrastructure in Akita mice. MK-801 did not alleviate reduced Akita mouse body weight and had no effect on kidney histology or ultrastructure in DBA/2J controls. The structurally dissimilar NMDA antagonist memantine also reduced diabetic nephropathy, although it was less effective than MK-801. Inhibition of NMDA receptors may represent a valid therapeutic approach to reduce renal complications of diabetes, and it is possible to develop well-tolerated agents with minimal central nervous system effects. Two such agents, memantine and dextromethorphan, are already in widespread clinical use. © 2016 by the American Diabetes Association.

  8. Simultaneous determination of D-aspartic acid and D-glutamic acid in rat tissues and physiological fluids using a multi-loop two-dimensional HPLC procedure.

    PubMed

    Han, Hai; Miyoshi, Yurika; Ueno, Kyoko; Okamura, Chieko; Tojo, Yosuke; Mita, Masashi; Lindner, Wolfgang; Zaitsu, Kiyoshi; Hamase, Kenji

    2011-11-01

    For a metabolomics study focusing on the analysis of aspartic and glutamic acid enantiomers, a fully automated two-dimensional HPLC system employing a microbore-ODS column and a narrowbore-enantioselective column was developed. By using this system, a detailed distribution of D-Asp and D-Glu besides L-Asp and L-Glu in mammals was elucidated. For the total analysis concept, the amino acids were first pre-column derivatized with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) to be sensitively and fluorometrically detected. For the non-stereoselective separation of the analytes in the first dimension a monolithic ODS column (750 mm × 0.53 mm i.d.) was adopted, and a self-packed narrowbore-Pirkle type enantioselective column (Sumichiral OA-2500S, 250 mm × 1.5 mm i.d.) was selected for the second dimension. In the rat plasma, RSD values for intra-day and inter-day precision were less than 6.8%, and the accuracy ranged between 96.1% and 105.8%. The values of LOQ of D-Asp and D-Glu were 5 fmol/injection (0.625 nmol/g tissue). The present method was successfully applied to the simultaneous determination of free aspartic acid and glutamic acid enantiomers in 7 brain areas, 11 peripheral tissues, plasma and urine of Wistar rats. Biologically significant D-Asp values were found in various tissue samples whereas for D-Glu the values were very low possibly indicating less significance. Copyright © 2011 Elsevier B.V. All rights reserved.

  9. Insulin-Like Growth Factor-I Regulates LH Release by Modulation of Kisspeptin and NMDA-Mediated Neurotransmission in Young and Middle-Aged Female Rats

    PubMed Central

    Yao, Dachun; Shu, Jun; Sun, Yan; Etgen, Anne M.

    2014-01-01

    This study investigated potential mechanisms by which age and IGF-I receptor (IGF-Ir) signaling in the neuroendocrine hypothalamus affect estradiol-positive feedback effects on GnRH neuronal activation and on kisspeptin and N-methyl-D-aspartate (NMDA)-induced LH release and on the abundance of NMDA receptor subunits Nr1 and Nr2b and Kiss1r transcript and protein in the hypothalamus of young and middle-aged female rats. We infused vehicle, IGF-I, or JB-1, a selective antagonist of IGF-Ir, into the third ventricle of ovariectomized female rats primed with estradiol or vehicle and injected with vehicle, kisspeptin (3 or 30 nmol/kg), or NMDA (15 or 30 mg/kg). Regardless of dose, NMDA and kisspeptin resulted in significantly more LH release, GnRH/c-Fos colabeling, and c-Fos immunoreative cells in young than in middle-aged females. Estradiol priming significantly increased Kiss1r, Nr1, and Nr2b receptor transcript and protein abundance in young but not middle-aged female hypothalamus. JB-1 attenuated kisspeptin and NMDA-induced LH release, numbers of GnRH/c-Fos and c-Fos cells, and Kiss1r, Nr1, and Nr2b transcript and protein abundance in young females to levels observed in middle-aged females. IGF-I significantly enhanced NMDA and kisspeptin-induced LH release in middle-aged females without increasing numbers of GnRH/c-Fos or c-Fos immunoreactive cells. IGF-I infusion in middle-aged females also increased Kiss1r, Nr1, and Nr2b protein and transcript to levels that were equivalent to young estradiol-primed females. These findings indicate that age-related changes in estradiol-regulated responsiveness to excitatory input from glutamate and kisspeptin reflect reduced IGF-Ir signaling. PMID:24617524

  10. D-Serine and a glycine transporter inhibitor improve MK-801-induced cognitive deficits in a novel object recognition test in rats.

    PubMed

    Karasawa, Jun-Ichi; Hashimoto, Kenji; Chaki, Shigeyuki

    2008-01-10

    Compounds enhancing N-methyl-d-aspartate (NMDA) glutamate receptor function have been reported to improve cognitive deficits. Since cognitive deficits are considered to be the core symptom of schizophrenia, enhancing NMDA receptor function represents a promising approach to treating schizophrenia. In the present study, we investigated whether d-serine or a glycine transporter inhibitor N-[3-(4'-fluorophenyl)-3-(4'-phenylphenoxy)propyl]sarcosine (NFPS), both of which enhance NMDA receptor function, could improve MK-801-induced cognitive deficits in rats, and compared their effects with those of the atypical antipsychotic clozapine and of the typical antipsychotic haloperidol. To assess cognitive function, we used a novel object recognition test in rats that measured spontaneous exploratory activity of a novel object when paired with a familiar object. We then evaluated the effects of the compounds on cognitive deficits induced by treatment with MK-801, the NMDA receptor antagonist. Pretreatment with clozapine (1, 5 mg/kg, i.p.) but not haloperidol (0.03, 0.1 mg/kg, i.p.) significantly improved MK-801-induced cognitive deficits. Pretreatment with D-serine at 800 mg/kg (i.p.) or NFPS (0.3, 1 mg/kg, i.p.) significantly improved MK-801-induced cognitive deficits under this test paradigm. These findings suggest that impaired preference for novel objects induced by MK-801 in the novel object recognition test could be a useful animal model for evaluating the efficacy of compounds targeting the cognitive deficits observed in schizophrenic patients. The results also suggest that enhancing NMDA receptor function is an effective way for treating the cognitive deficits associated with schizophrenia.

  11. Anti–N-Methyl-D-Aspartate Receptor (NMDAR) Encephalitis in Children and Adolescents

    PubMed Central

    Florance, Nicole R.; Davis, Rebecca L.; Lam, Christopher; Szperka, Christina; Zhou, Lei; Ahmad, Saba; Campen, Cynthia J.; Moss, Heather; Peter, Nadja; Gleichman, Amy J.; Glaser, Carol A.; Lynch, David R.; Rosenfeld, Myrna R.; Dalmau, Josep

    2010-01-01

    Objective To report the clinical features of anti–N-methyl-D-aspartate receptor (NMDAR) encephalitis in patients ≤ 18 years old. Methods Information was obtained by the authors or referring physicians. Antibodies were determined by immunocytochemistry and enzyme-linked immunosorbent assay (ELISA) using HEK293 cells ectopically expressing NR1. Results Over an 8-month period, 81 patients (12 male) with anti-NMDAR encephalitis were identified. Thirty-two (40%) were ≤18 years old (youngest 23 months, median 14 years); 6 were male. The frequency of ovarian teratomas was 56% in women >18 years old, 31% in girls ≤18 years old (p = 0.05), and 9% in girls ≤14 years old ( p = 0.008). None of the male patients had tumors. Of 32 patients ≤18 years old, 87.5% presented with behavioral or personality change, sometimes associated with seizures and frequent sleep dysfunction; 9.5% with dyskinesias or dystonia; and 3% with speech reduction. On admission, 53% had severe speech deficits. Eventually, 77% developed seizures, 84% stereotyped movements, 86% autonomic instability, and 23% hypoventilation. Responses to immunotherapy were slow and variable. Overall, 74% had full or substantial recovery after immunotherapy or tumor removal. Neurological relapses occurred in 25%. At the last follow-up, full recovery occurred more frequently in patients who had a teratoma that was removed (5/8) than in those without a teratoma (4/23; p = 0.03). Interpretation Anti-NMDAR encephalitis is increasingly recognized in children, comprising 40% of all cases. Younger patients are less likely to have tumors. Behavioral and speech problems, seizures, and abnormal movements are common early symptoms. The phenotype resembles that of the adults, although dysautonomia and hypoventilation are less frequent or severe in children. PMID:19670433

  12. Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis in children and adolescents.

    PubMed

    Florance, Nicole R; Davis, Rebecca L; Lam, Christopher; Szperka, Christina; Zhou, Lei; Ahmad, Saba; Campen, Cynthia J; Moss, Heather; Peter, Nadja; Gleichman, Amy J; Glaser, Carol A; Lynch, David R; Rosenfeld, Myrna R; Dalmau, Josep

    2009-07-01

    To report the clinical features of anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis in patients < or = 18 years old. Information was obtained by the authors or referring physicians. Antibodies were determined by immunocytochemistry and enzyme-linked immunosorbent assay (ELISA) using HEK293 cells ectopically expressing NR1. Over an 8-month period, 81 patients (12 male) with anti-NMDAR encephalitis were identified. Thirty-two (40%) were < or =18 years old (youngest 23 months, median 14 years); 6 were male. The frequency of ovarian teratomas was 56% in women >18 years old, 31% in girls < or =18 years old (p = 0.05), and 9% in girls < or =14 years old (p = 0.008). None of the male patients had tumors. Of 32 patients < or =18 years old, 87.5% presented with behavioral or personality change, sometimes associated with seizures and frequent sleep dysfunction; 9.5% with dyskinesias or dystonia; and 3% with speech reduction. On admission, 53% had severe speech deficits. Eventually, 77% developed seizures, 84% stereotyped movements, 86% autonomic instability, and 23% hypoventilation. Responses to immunotherapy were slow and variable. Overall, 74% had full or substantial recovery after immunotherapy or tumor removal. Neurological relapses occurred in 25%. At the last follow-up, full recovery occurred more frequently in patients who had a teratoma that was removed (5/8) than in those without a teratoma (4/23; p = 0.03). Anti-NMDAR encephalitis is increasingly recognized in children, comprising 40% of all cases. Younger patients are less likely to have tumors. Behavioral and speech problems, seizures, and abnormal movements are common early symptoms. The phenotype resembles that of the adults, although dysautonomia and hypoventilation are less frequent or severe in children. Ann Neurol 2009;66:11-18.

  13. LSD and DOB: interaction with 5-HT2A receptors to inhibit NMDA receptor-mediated transmission in the rat prefrontal cortex.

    PubMed

    Arvanov, V L; Liang, X; Russo, A; Wang, R Y

    1999-09-01

    Both the phenethylamine hallucinogen (-)-1-2, 5-dimethoxy-4-bromophenyl-2-aminopropane (DOB), a selective serotonin 5-HT2A,2C receptor agonist, and the indoleamine hallucinogen D-lysergic acid diethylamide (LSD, which binds to 5-HT1A, 1B, 1D, 1E, 1F, 2A, 2C, 5, 6, 7, dopamine D1 and D2, and alpha1 and alpha2 adrenergic receptors), but not their non-hallucinogenic congeners, inhibited N-methyl-D-aspartate (NMDA)-induced inward current and NMDA receptor-mediated synaptic responses evoked by electrical stimulation of the forceps minor in pyramidal cells of the prefrontal cortical slices. The inhibitory effect of hallucinogens was mimicked by 5-HT in the presence of selective 5-HT1A and 5-HT3 receptor antagonists. The inhibitory action of DOB, LSD and 5-HT on the NMDA transmission was blocked by the 5-HT2A receptor antagonists R-(+)-alpha-(2, 3-dimethoxyphenil)-1-[4-fluorophenylethyl]-4-piperidineme thanol (M100907) and ketanserin. However, at low concentrations, when both LSD and DOB by themselves only partially depressed the NMDA response, they blocked the inhibitory effect of 5-HT, suggesting a partial agonist action. Whereas N-(4-aminobutyl)-5-chloro-2-naphthalenesulphonamide (W-7, a calmodulin antagonist) and N-[2-[[[3-(4'-chlorophenyl)- 2-propenyl]methylamino]methyl]phenyl]-N-(2-hydroxyethyl)-4'-methoxy-b enzenesulphonamide phosphate (KN-93, a Ca2+/CaM-KII inhibitor), but not the negative control 2-[N-4'methoxybenzenesulphonyl]amino-N-(4'-chlorophenyl)-2-propeny l-N -methylbenzylamine phosphate (KN-92), blocked the inhibitory action of LSD and DOB, the selective protein kinase C inhibitor chelerythrine was without any effect. We conclude that phenethylamine and indoleamine hallucinogens may exert their hallucinogenic effect by interacting with 5-HT2A receptors via a Ca2+/CaM-KII-dependent signal transduction pathway as partial agonists and modulating the NMDA receptors-mediated sensory, perceptual, affective and cognitive processes.

  14. Combination of aspartic acid and glutamic acid inhibits tumor cell proliferation.

    PubMed

    Yamaguchi, Yoshie; Yamamoto, Katsunori; Sato, Yoshinori; Inoue, Shinjiro; Morinaga, Tetsuo; Hirano, Eiichi

    2016-01-01

    Placental extract contains several biologically active compounds, and pharmacological induction of placental extract has therapeutic effects, such as improving liver function in patients with hepatitis or cirrhosis. Here, we searched for novel molecules with an anti-tumor activity in placental extracts. Active molecules were separated by chromatographic analysis, and their antiproliferative activities were determined by a colorimetric assay. We identified aspartic acid and glutamic acid to possess the antiproliferative activity against human hepatoma cells. Furthermore, we showed that the combination of aspartic acid and glutamic acid exhibited enhanced antiproliferative activity, and inhibited Akt phosphorylation. We also examined in vivo tumor inhibition activity using the rabbit VX2 liver tumor model. The treatment mixture (emulsion of the amino acids with Lipiodol) administered by hepatic artery injection inhibited tumor cell growth of the rabbit VX2 liver. These results suggest that the combination of aspartic acid and glutamic acid may be useful for induction of tumor cell death, and has the potential for clinical use as a cancer therapeutic agent.

  15. CORM-A1 prevents blood-brain barrier dysfunction caused by ionotropic glutamate receptor-mediated endothelial oxidative stress and apoptosis.

    PubMed

    Basuroy, Shyamali; Leffler, Charles W; Parfenova, Helena

    2013-06-01

    In cerebral microvascular endothelial cells (CMVEC) of newborn pigs, glutamate at excitotoxic concentrations (mM) causes apoptosis mediated by reactive oxygen species (ROS). Carbon monoxide (CO) produced by CMVEC or delivered by a CO-releasing molecule, CORM-A1, has antioxidant properties. We tested the hypothesis that CORM-A1 prevents cerebrovascular endothelial barrier dysfunction caused by glutamate excitotoxicity. First, we identified the glutamate receptors (GluRs) and enzymatic sources of ROS involved in the mechanism of endothelial apoptosis. In glutamate-exposed CMVEC, ROS formation and apoptosis were blocked by rotenone, 2-thenoyltrifluoroacetone (TTFA), and antimycin, indicating that mitochondrial complexes I, II, and III are the major sources of oxidative stress. Agonists of ionotropic GluRs (iGluRs) N-methyl-D-aspartate (NMDA), cis-ACPD, AMPA, and kainate increased ROS production and apoptosis, whereas iGluR antagonists exhibited antiapoptotic properties, suggesting that iGluRs mediate glutamate-induced endothelial apoptosis. The functional consequences of endothelial injury were tested in the model of blood-brain barrier (BBB) composed of CMVEC monolayer on semipermeable membranes. Glutamate and iGluR agonists reduced transendothelial electrical resistance and increased endothelial paracellular permeability to 3-kDa dextran. CORM-A1 exhibited potent antioxidant and antiapoptotic properties in CMVEC and completely prevented BBB dysfunction caused by glutamate and iGluR agonists. Overall, the endothelial component of the BBB is a cellular target for excitotoxic glutamate that, via a mechanism involving a iGluR-mediated activation of mitochondrial ROS production and apoptosis, leads to BBB opening that may be prevented by the antioxidant and antiapoptotic actions of CORMs. Antioxidant CORMs therapy may help preserve BBB functional integrity in neonatal cerebrovascular disease.

  16. The effects of an intraperitoneal single low dose of ketamine in attenuating the postoperative skin/muscle incision and retraction-induced pain related to the inhibition of N-methyl-D-aspartate receptors in the spinal cord.

    PubMed

    Shen, Yu; Xu, Li; Liu, Ming; Lei, Yishan; Gu, Xiaoping; Ma, Zhengliang

    2016-03-11

    Chronic postoperative pain (CPOP) is a common clinical problem which might be related to central sensitization. It has been widely accepted that NMDA (N-methyl-D-aspartate) receptors are among the triggers of central sensitization. Ketamine is a non-competitive NMDA receptor antagonist that is widely used in alleviating postoperative pain, but its effect on CPOP has been rarely reported. In the present study, the skin/muscle incision and retraction (SMIR) model was used to investigate the role of NMDARs in chronic postoperative pain and the effect of an intraperitoneal single low dose ketamine (10mg/kg) of attenuating SMIR-induced CPOP. We assessed pain behaviours after a SMIR operation by paw withdrawal threshold (PWMT) and paw withdrawal latency (PWMTL). Western blotting were performed to examine the role of NMDARs in SMIR-induced CPOP and the effect of ketamine on the expression and phosphorylation of NMDARs. The SMIR operation induced long-lasting mechanical hyperalgesia, and the up-regulation of phosphorylated NMDARs and total NMDARs at the spinal level. A single intraperitoneal administration of low dose ketamine (10mg/kg) during surgery alleviated pain behaviors and inhibited the up-regulation of phosphorylated NMDARs and total NMDARs. Our datas suggested that NMDARs play important roles in SMIR-induced CPOP. A single intraperitoneal low dose of ketamine could attenuate SMIR-induced CPOP, which might be associated with the inhibition of NMDARs. Our finding might provide a new, simple method of addressing CPOP. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  17. Temporal-difference prediction errors and Pavlovian fear conditioning: role of NMDA and opioid receptors.

    PubMed

    Cole, Sindy; McNally, Gavan P

    2007-10-01

    Three experiments studied temporal-difference (TD) prediction errors during Pavlovian fear conditioning. In Stage I, rats received conditioned stimulus A (CSA) paired with shock. In Stage II, they received pairings of CSA and CSB with shock that blocked learning to CSB. In Stage III, a serial overlapping compound, CSB --> CSA, was followed by shock. The change in intratrial durations supported fear learning to CSB but reduced fear of CSA, revealing the operation of TD prediction errors. N-methyl- D-aspartate (NMDA) receptor antagonism prior to Stage III prevented learning, whereas opioid receptor antagonism selectively affected predictive learning. These findings support a role for TD prediction errors in fear conditioning. They suggest that NMDA receptors contribute to fear learning by acting on the product of predictive error, whereas opioid receptors contribute to predictive error. (PsycINFO Database Record (c) 2007 APA, all rights reserved).

  18. Interactions of MK-801 with glutamate-, glutamine- and methamphetamine-evoked release of ( sup 3 H)dopamine from striatal slices

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bowyer, J.F.; Scallet, A.C.; Holson, R.R.

    1991-04-01

    The interactions of MK-801 ((+)-5-methyl-10,11-dihydro-5H-dibenzo(a,d) cyclohepten-5,10-imine), glutamate and glutamine with methamphetamine (METH)-evoked release of ({sup 3}H)dopamine were assessed in vitro to determine whether MK-801 inhibition of METH neurotoxicity might be mediated presynaptically, and to evaluate the effects of glutamatergic stimulation on METH-evoked dopamine release. MK-801 inhibition of glutamate- or METH-evoked dopamine release might reduce synaptic dopamine levels during METH exposure and decrease the formation of 6-hydroxydopamine or other related neurotoxins. Without Mg{sup 2}{sup +} present, 40 microM and 1 mM glutamate evoked a N-methyl-D-aspartate receptor-mediated ({sup 3}H)dopamine and ({sup 3}H)metabolite (tritium) release of 3 to 6 and 12 to 16%more » of total tritium stores, respectively, from striatal slices. With 1.50 mM Mg{sup 2}{sup +} present, 10 mM glutamate alone or in combination with the dopamine uptake blocker nomifensine released only 2.1 or 4.2%, respectively, of total tritium stores, and release was only partially dependent on N-methyl-D-aspartate-type glutamate receptors. With or without 1.50 mM Mg{sup 2}{sup +} present, 0.5 or 5 microM METH evoked a substantial release of tritium (5-8 or 12-21% of total stores, respectively). METH-evoked dopamine release was not affected by 5 microM MK-801 but METH-evoked release was additive with glutamate-evoked release. Without Mg{sup 2}{sup +} present, 1 mM glutamine increased glutamate release and induced the release of ({sup 3}H)dopamine and metabolites. Both 0.5 and 5 microM METH also increased tritium release with 1 mM glutamine present. When striatal slices were exposed to 5 microM METH this glutamine-evoked release of glutamate was increased more than 50%.« less

  19. Structural basis of subunit selectivity for competitive NMDA receptor antagonists with preference for GluN2A over GluN2B subunits

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lind, Genevieve E.; Mou, Tung-Chung; Tamborini, Lucia

    NMDA-type glutamate receptors are ligand-gated ion channels that contribute to excitatory neurotransmission in the central nervous system (CNS). Most NMDA receptors comprise two glycine-binding GluN1 and two glutamate-binding GluN2 subunits (GluN2A–D). We describe highly potent (S)-5-[(R)-2-amino-2-carboxyethyl]-4,5-dihydro-1H-pyrazole-3-carboxylic acid (ACEPC) competitive GluN2 antagonists, of which ST3 has a binding affinity of 52 nM at GluN1/2A and 782 nM at GluN1/2B receptors. This 15-fold preference of ST3 for GluN1/2A over GluN1/2B is improved compared with NVP-AAM077, a widely used GluN2A-selective antagonist, which we show has 11-fold preference for GluN1/2A over GluN1/2B. Crystal structures of the GluN1/2A agonist binding domain (ABD) heterodimer with boundmore » ACEPC antagonists reveal a binding mode in which the ligands occupy a cavity that extends toward the subunit interface between GluN1 and GluN2A ABDs. Mutational analyses show that the GluN2A preference of ST3 is primarily mediated by four nonconserved residues that are not directly contacting the ligand, but positioned within 12 Å of the glutamate binding site. Two of these residues influence the cavity occupied by ST3 in a manner that results in favorable binding to GluN2A, but occludes binding to GluN2B. Thus, we reveal opportunities for the design of subunit-selective competitive NMDA receptor antagonists by identifying a cavity for ligand binding in which variations exist between GluN2A and GluN2B subunits. This structural insight suggests that subunit selectivity of glutamate-site antagonists can be mediated by mechanisms in addition to direct contributions of contact residues to binding affinity.« less

  20. Structural basis of subunit selectivity for competitive NMDA receptor antagonists with preference for GluN2A over GluN2B subunits

    PubMed Central

    Lind, Genevieve E.; Mou, Tung-Chung; Tamborini, Lucia; Pomper, Martin G.; De Micheli, Carlo; Conti, Paola; Pinto, Andrea

    2017-01-01

    NMDA-type glutamate receptors are ligand-gated ion channels that contribute to excitatory neurotransmission in the central nervous system (CNS). Most NMDA receptors comprise two glycine-binding GluN1 and two glutamate-binding GluN2 subunits (GluN2A–D). We describe highly potent (S)-5-[(R)-2-amino-2-carboxyethyl]-4,5-dihydro-1H-pyrazole-3-carboxylic acid (ACEPC) competitive GluN2 antagonists, of which ST3 has a binding affinity of 52 nM at GluN1/2A and 782 nM at GluN1/2B receptors. This 15-fold preference of ST3 for GluN1/2A over GluN1/2B is improved compared with NVP-AAM077, a widely used GluN2A-selective antagonist, which we show has 11-fold preference for GluN1/2A over GluN1/2B. Crystal structures of the GluN1/2A agonist binding domain (ABD) heterodimer with bound ACEPC antagonists reveal a binding mode in which the ligands occupy a cavity that extends toward the subunit interface between GluN1 and GluN2A ABDs. Mutational analyses show that the GluN2A preference of ST3 is primarily mediated by four nonconserved residues that are not directly contacting the ligand, but positioned within 12 Å of the glutamate binding site. Two of these residues influence the cavity occupied by ST3 in a manner that results in favorable binding to GluN2A, but occludes binding to GluN2B. Thus, we reveal opportunities for the design of subunit-selective competitive NMDA receptor antagonists by identifying a cavity for ligand binding in which variations exist between GluN2A and GluN2B subunits. This structural insight suggests that subunit selectivity of glutamate-site antagonists can be mediated by mechanisms in addition to direct contributions of contact residues to binding affinity. PMID:28760974

  1. An ionotropic but not a metabotropic glutamate agonist potentiates the pharmacological effects of olanzapine in the rat.

    PubMed

    Dall'Olio, Rossella; Rimondini, Roberto; Locchi, Federica; Voltattorni, Manuela; Gandolfi, Ottavio

    2005-12-01

    This study aimed to evaluate the possible potentiating action of ionotropic or metabotropic (metabotropic glutamate receptor type 5) glutamate agonists on pharmacological effects induced in rats by the atypical antipsychotic olanzapine. The administration of doses of olanzapine, which did not affect spontaneous motility, inhibited behaviors induced by the selective stimulation of 5HT(2A) and D(2) receptors. In particular, 0.03 or 0.06 mg/kg of olanzapine was sufficient to reduce, respectively, head shakes induced by the 5HT(2A) agonist 1-2,5-dimethoxy-4-iodophenyl-2-aminopropane (1 mg/kg) or hypermotility elicited by the D(2) stimulant quinpirole (0.15 mg/kg). Behavioral responses to a D(1)/D(2) agonist (apomorphine-induced stereotypies) were inhibited by doses of olanzapine that also influenced spontaneous behavior. The concomitant administration of D-cycloserine, an agonist at the glycine site on the N-methyl-D-aspartate receptor complex, given at a dose (3 mg/kg) that did not affect behavior, increased the inhibitory effect of olanzapine on the responses produced by 5HT2A, D(2) and D(1)/D(2) receptor stimulation. The concomitant administration of 2-chloro-5-hydroxyphenylglycine, an agonist of metabotropic glutamate receptor type 5, increased the inhibitory effect of olanzapine on the behaviors induced by the stimulation of D(2), but not 5HT2A or D(1)/D(2) receptors. As the effect on the serotonergic system seems important for the unusual pharmacological profile of atypical antipsychotics, the present results suggest that N-methyl-D-aspartate, but not metabotropic glutamate receptor type 5 agonists could be seen as promising therapeutic agents for increasing the pharmacological effects of olanzapine.

  2. Lanicemine: a low-trapping NMDA channel blocker produces sustained antidepressant efficacy with minimal psychotomimetic adverse effects.

    PubMed

    Sanacora, G; Smith, M A; Pathak, S; Su, H-L; Boeijinga, P H; McCarthy, D J; Quirk, M C

    2014-09-01

    Ketamine, an N-methyl-D-aspartate receptor (NMDAR) channel blocker, has been found to induce rapid and robust antidepressant-like effects in rodent models and in treatment-refractory depressed patients. However, the marked acute psychological side effects of ketamine complicate the interpretation of both preclinical and clinical data. Moreover, the lack of controlled data demonstrating the ability of ketamine to sustain the antidepressant response with repeated administration leaves the potential clinical utility of this class of drugs in question. Using quantitative electroencephalography (qEEG) to objectively align doses of a low-trapping NMDA channel blocker, AZD6765 (lanicemine), to that of ketamine, we demonstrate the potential for NMDA channel blockers to produce antidepressant efficacy without psychotomimetic and dissociative side effects. Furthermore, using placebo-controlled data, we show that the antidepressant response to NMDA channel blockers can be maintained with repeated and intermittent drug administration. Together, these data provide a path for the development of novel glutamatergic-based therapeutics for treatment-refractory mood disorders.

  3. Memantine Protects Rats Treated with Intrathecal Methotrexate from Developing Spatial Memory Deficits

    PubMed Central

    Cole, Peter D.; Vijayanathan, Veena; Ali, Nafeeza F.; Wagshul, Mark E.; Tanenbaum, Eric J.; Price, Jeremy; Dalal, Vidhi; Gulinello, Maria E.

    2014-01-01

    Purpose To test whether memantine can prevent methotrexate-induced cognitive deficits in a preclinical model. Experimental Design After noting that methotrexate exposure induces prolonged elevations of the glutamate analog homocysteic acid (HCA) within cerebrospinal fluid, we tested whether intrathecal injection of HCA would produce memory deficits similar to those observed after intrathecal methotrexate. We then tested whether memantine, an antagonist of the N-methyl-D-aspartate (NMDA) subclass of glutamate receptors, could protect animals treated with clinically relevant doses of intrathecal methotrexate against developing memory deficits. Finally, we asked whether memantine affected this pathway beyond inhibiting the NMDA receptor by altering expression of the NMDA receptor or affecting concentrations of HCA or glutamate within the central nervous system. Results Four intrathecal doses of methotrexate induced deficits in spatial memory, persisting at least one month following the final injection. Intrathecal HCA was sufficient to reproduce this deficit. Concurrent administration of memantine during the period of methotrexate exposure was protective, decreasing the incidence of methotrexate-induced spatial memory deficits from 56% to 20% (P < 0.05). Memantine neither altered expression of NMDA receptors within the hippocampus nor blunted the methotrexate-induced increases in glutamate or HCA. Conclusions Excitotoxic glutamate analogs including HCA contribute to cognitive deficits observed after intrathecal methotrexate. Memantine, an NMDA receptor antagonist, reduces the incidence of cognitive deficits in rats treated with intrathecal methotrexate, and may therefore benefit patients with cancer receiving similar treatment. PMID:23833301

  4. Differential Modulation of Ethanol-Induced Sedation and Hypnosis by Metabotropic Glutamate Receptor Antagonists in C57BL/6J Mice

    PubMed Central

    Sharko, Amanda C.; Hodge, Clyde W.

    2008-01-01

    Background Emerging evidence implicates metabotropic glutamate receptor (mGluR) function in the neurobiological effects of ethanol. The recent development of subtype specific mGluR antagonists has made it possible to examine the roles of specific mGluRs in biochemical and behavioral responses to ethanol. The purpose of the present study was to determine if mGluRs modulate the acute sedative-hypnotic properties of ethanol in mice. Methods C57BL / 6J mice were tested for locomotor activity (sedation) and duration of loss of the righting reflex (hypnosis) following acute systemic administration of ethanol alone or in combination with the mGluR5-selective antagonist, 2-methyl-6-(phenylethynyl)pyridine (MPEP), the mGluR1-selective antagonist, 7-(hydroxyimino)cyclopropa[b]chromen-1a-carboxylate ethyl ester (CPCCOEt), or the mGluR2 / 3-selective antagonist (2S)-2-Amino-2-[(1S,2S)-2-carboxycycloprop-1-yl]-3-(xanth-9-yl) propanoic acid (LY341495)). Results MPEP (10 and 30 mg / kg) significantly enhanced both the sedative and hypnotic effects of ethanol, while LY341495 (10 and 30 mg / kg) significantly reduced the sedative-hypnotic effects of ethanol. CPCCOEt had no effect at any concentration tested. Further loss of righting reflex experiments revealed that LY341495 (30 mg / kg) significantly reduced hypnosis induced by the gamma-aminobutyric acid type A (GABAA) positive modulators, pentobarbital (50 mg / kg) and midazolam (60 mg / kg), and the N-methyl-D-aspartate (NMDA) receptor antagonist, ketamine (150 mg / kg), while MPEP (30 mg / kg) only significantly enhanced the hypnotic properties of ketamine (150 mg / kg). Conclusions These findings suggest that specific subtypes of the metabotropic glutamate receptor differentially modulate the sedative-hypnotic properties of ethanol through separate mechanisms of action, potentially involving GABAA and NMDA receptors. PMID:18070246

  5. Neuroprotection in rabbit retina with N-acetyl-aspartylglutamate and 2-phosphonyl-methyl pentanedioic acid

    NASA Astrophysics Data System (ADS)

    Hacker, Henry D.; Yourick, Debra L.; Koenig, Michael K.; Slusher, Barbara S.; Meyerhoff, James L.

    1999-06-01

    Retinal tissue is subject to ischemia from diabetic retinopathy and other conditions that affect the retinal vasculature such as lupus erythematosus and temporal arteritis. There is evidence in animal models of reversible ischemia that a therapeutic window exists during early recovery when agents that reduce glutamate activity at its receptor sites can rescue neurons from injury. To model ischemia, we used sodium cyanide (NaCN), to inhibit oxidative metabolism, and 2-deoxyglucose (2-DG) to inhibit glycolysis. Dissociated rabbit retina cells were studied to evaluate the potential neuroprotective effects of N-acetyl-aspartyl-glutamate (MAAG), which competes with glutamate as a low-potency agonist at the NMDA receptor complex. N-acetylated α-linked acidic dipeptidase (NAALADase; the NAAG-hydrolyzing enzyme) is responsible for the hydrolysis of NAAG into glutamate, a neurotransmitter and potent excitotoxin, and N-acetylaspartate. 2-Phosphonyl-methyl pentanedioic acid (PMPA) and β-linked NAAG (β-NAAG), inhibitors of NAALADase, were also tested, since inhibition of NAALADase could reduce synaptic glutamate and increase the concentration of NAAG. We found that metabolic inhibition with NaCN/2-DG for 1 hour caused 50% toxicity as assessed with the MTT assay. Co-treatment with NAAG resulted in dose-dependent protection of up to 55% (p<0.005). When the non-hydrolyzable, NAALADase inhibitor β-NAAG was employed dose-dependent protection of up to 37% was observed (p<0.001). PMPA also showed 48% protection (p<.05-.001) against these insults. These data suggest that NAAG may antagonize the effect of glutamate at the NMDA receptor complex in retina. Inhibition of NAALADase by PMPA and β-NAAG may increase the activity of endogenous NAAG.

  6. Autistic-like social behaviour in Shank2-mutant mice improved by restoring NMDA receptor function.

    PubMed

    Won, Hyejung; Lee, Hye-Ryeon; Gee, Heon Yung; Mah, Won; Kim, Jae-Ick; Lee, Jiseok; Ha, Seungmin; Chung, Changuk; Jung, Eun Suk; Cho, Yi Sul; Park, Sae-Geun; Lee, Jung-Soo; Lee, Kyungmin; Kim, Daesoo; Bae, Yong Chul; Kaang, Bong-Kiun; Lee, Min Goo; Kim, Eunjoon

    2012-06-13

    Autism spectrum disorder (ASD) is a group of conditions characterized by impaired social interaction and communication, and restricted and repetitive behaviours. ASD is a highly heritable disorder involving various genetic determinants. Shank2 (also known as ProSAP1) is a multi-domain scaffolding protein and signalling adaptor enriched at excitatory neuronal synapses, and mutations in the human SHANK2 gene have recently been associated with ASD and intellectual disability. Although ASD-associated genes are being increasingly identified and studied using various approaches, including mouse genetics, further efforts are required to delineate important causal mechanisms with the potential for therapeutic application. Here we show that Shank2-mutant (Shank2(-/-)) mice carrying a mutation identical to the ASD-associated microdeletion in the human SHANK2 gene exhibit ASD-like behaviours including reduced social interaction, reduced social communication by ultrasonic vocalizations, and repetitive jumping. These mice show a marked decrease in NMDA (N-methyl-D-aspartate) glutamate receptor (NMDAR) function. Direct stimulation of NMDARs with D-cycloserine, a partial agonist of NMDARs, normalizes NMDAR function and improves social interaction in Shank2(-/-) mice. Furthermore, treatment of Shank2(-/-) mice with a positive allosteric modulator of metabotropic glutamate receptor 5 (mGluR5), which enhances NMDAR function via mGluR5 activation, also normalizes NMDAR function and markedly enhances social interaction. These results suggest that reduced NMDAR function may contribute to the development of ASD-like phenotypes in Shank2(-/-) mice, and mGluR modulation of NMDARs offers a potential strategy to treat ASD.

  7. High extracellular concentration of excitatory amino acids glutamate and aspartate in human brain abscess.

    PubMed

    Dahlberg, Daniel; Ivanovic, Jugoslav; Hassel, Bjørnar

    2014-04-01

    Brain abscesses often cause symptoms of brain dysfunction, including seizures, suggesting interference with normal neurotransmission. We determined the concentration of extracellular neuroactive amino acids in brain abscesses from 16 human patients. Glutamate was present at 3.6 mmol/L (median value, range 0.5-10.8), aspartate at 1.0 mmol/L (range 0.09-6.8). For comparison, in cerebroventricular fluid glutamate was ∼0.6 μmol/L, and aspartate was not different from zero. The total concentration of amino acids was higher in eight patients with seizures: 66 mmol/L (median value, range 19-109) vs. 21 mmol/L (range 4-52) in eight patients without seizures (p=0.026). The concentration of aspartate and essential amino acids tryptophan, phenylalanine, tyrosine, leucine, and isoleucine was higher in pus from patients with seizures (p⩽0.040), whereas that of glutamate was not (p=0.095). The median concentration of the non-proteinogenic, inhibitory amino acid taurine was similar in the two groups, 0.7-0.8 mmol/L (range 0.1-6.1). GABA could not be detected in pus. The patient groups did not differ with respect to abscess volume, the cerebral lobe affected, age, or time from symptom onset to surgery. Seven patients with extracerebral, intracranial abscesses had significantly lower pus concentration of glutamate (352 μmol/L, range 83-1368) and aspartate (71 μmol/L, range 22-330) than intracerebral abscesses (p<0.001). We conclude that excitatory amino acids glutamate and aspartate may reach very high concentrations in brain abscesses, probably contributing to symptoms through activation of glutamate receptors in the surrounding brain tissue. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. 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

  9. Neuropsychiatric disturbances in SLE are associated with antibodies against NMDA receptors.

    PubMed

    Omdal, R; Brokstad, K; Waterloo, K; Koldingsnes, W; Jonsson, R; Mellgren, S I

    2005-05-01

    To determine whether neuropsychiatric manifestations in patients with systemic lupus erythematosus (SLE) are influenced by antibodies against the human N-methyl-D-aspartate (NMDA) receptor types NR2a or NR2b. A decapeptide was synthesized containing a sequence motif present in the extracellular ligand-binding domain of NMDA receptors NR2a and NR2b, bound by the monoclonal murine anti-DNA antibody R4A. In an ELISA with the murine monoclonal R4v as positive control, plasma samples of 57 patients with SLE were examined for the anti-peptide (anti-NR2) antibody after the patients had been subjected to comprehensive psychological and cognitive testing. Poor performance on the Visual Paired Associates test (immediate), the Grooved Pegboard test, as well as high scores on the Beck Depression Inventory, and scales D-2 (depression), Pd-4 (psychopathic deviate), Sc-8 (schizophrenia), and Ma-9 (hypomania) of the MMPI-2 were significantly associated with elevated levels of anti-NR2 antibodies. The findings in several domains indicate an association between anti-NR2 antibodies and depressed mood in addition to decreased short-time memory and learning. Antibodies to NMDA receptors thus may represent one of several mechanisms for cerebral dysfunction in patients with SLE.

  10. The drugs don't work-or do they? Pharmacological and transgenic studies of the contribution of NMDA and GluR-A-containing AMPA receptors to hippocampal-dependent memory.

    PubMed

    Bannerman, D M; Rawlins, J N P; Good, M A

    2006-11-01

    The aim of this article is to provide a review of studies using N-methyl-D-aspartate (NMDA) receptor antagonists to assess the hippocampal long-term potentiation (LTP)/learning hypothesis. In particular, we will re-examine the validity of both (1) the original hippocampal LTP/spatial learning hypothesis of Morris and (2) the sensorimotor account put forward by Cain, among others, both from the point of view of the pharmacological studies on which they were based and with regard to recent studies with genetically modified mice. More specifically, we will review the pharmacological studies in the light of recent work on the glutamate receptor A (GluR-A or GluR1) L-alpha-amino-3-hydroxy-5-methyl-4-isoxazelopropionate (AMPA) receptor sub-unit knockout mouse. We will argue that neither the original hippocampal LTP/spatial learning hypothesis nor a sensorimotor account can adequately explain all of the available data. We argue instead that hippocampal synaptic plasticity, which requires NMDA receptors for its induction and GluR-A-containing AMPA receptors for its continued expression, contributes to a process whereby appropriate behavioural responses are selected rapidly on the basis of conditional information provided by the context. These contextual cues could include not only the spatial context (i.e. the 'where') and the temporal context (the 'when'), but also other aspects of context, such as internal state cues (hunger and fear state), and can be used to rapidly and flexibly alter valences of specific response options. We also suggest that there is a separate, distinct, NMDA/GluR-A-independent mechanism through which the context can gradually (incrementally or decrementally) alter the valence of a particular response option.

  11. Gender specific influence of endogenous glutamate release on stress-induced fear in rats.

    PubMed

    Jain, S K; Zelena, D

    2011-01-01

    Stress, fear and anxiety are among major public health concerns. The role of glutamate in these processes is becoming more recognized with promising new drug targets. The aim of this study was to establish the gender specificity of a possible treatment of fear by glutamate antagonists in correspondence with changes in stress-hormone release. Footshock-induced fear was used as an anxiogenic situation in rats. A combination of two ionotrop receptor antagonists such as MK-801 (dizocilpine; 0.2 mg/kg) for NMDA (N-methyl-D-aspartic acid) and GYKI 52466 (benzodiazepine derivative; 10 mg/kg) for AMPA/kainate receptors were used for 5 days following the hypothesis that they potentiate each other the main action, but at the same time the side effects may be minimized. Female rats tried to avoid the electrical stimulus more actively than males, as they spent more time with exploration and jumping and less time with freezing or rest. Ionotropic glutamate receptor antagonists have anxiolytic action. MK-801 was more effective in females, as it prevented the footshock-induced freezing per se, while in males it was effective only in combination with GyKI 52466. The locomotor side effect of MK-801 was not visible after repeated administration. The freezing behavior was positively correlated with the changes in prolactin but not with adrenocorticotropin levels. We proved the involvement of endogenous glutamate neurotransmission in stress-induced fear. Therapeutical usage may involve a combination of different receptor antagonists. Special attention should be paid to the gender, as females seem to be more sensitive, therefore they require smaller doses. During the treatment the prolactin levels should be monitored.

  12. Prenatal exposure to phencyclidine produces abnormal behaviour and NMDA receptor expression in postpubertal mice.

    PubMed

    Lu, Lingling; Mamiya, Takayoshi; Lu, Ping; Toriumi, Kazuya; Mouri, Akihiro; Hiramatsu, Masayuki; Kim, Hyoung-Chun; Zou, Li-Bo; Nagai, Taku; Nabeshima, Toshitaka

    2010-08-01

    Several studies have shown the disruptive effects of non-competitive N-methyl-d-aspartate (NMDA) receptor antagonists on neurobehavioural development. Based on the neurodevelopment hypothesis of schizophrenia, there is growing interest in animal models treated with NMDA antagonists at developing stages to investigate the pathogenesis of psychological disturbances in humans. Previous studies have reported that perinatal treatment with phencyclidine (PCP) impairs the development of neuronal systems and induces schizophrenia-like behaviour. However, the adverse effects of prenatal exposure to PCP on behaviour and the function of NMDA receptors are not well understood. This study investigated the long-term effects of prenatal exposure to PCP in mice. The prenatal PCP-treated mice showed hypersensitivity to a low dose of PCP in locomotor activity and impairment of recognition memory in the novel object recognition test at age 7 wk. Meanwhile, the prenatal exposure reduced the phosphorylation of NR1, although it increased the expression of NR1 itself. Furthermore, these behavioural changes were attenuated by atypical antipsychotic treatment. Taken together, prenatal exposure to PCP produced long-lasting behavioural deficits, accompanied by the abnormal expression and dysfunction of NMDA receptors in postpubertal mice. It is worth investigating the influences of disrupted NMDA receptors during the prenatal period on behaviour in later life.

  13. Memory in aged mice is rescued by enhanced expression of the GluN2B subunit of the NMDA receptor

    PubMed Central

    Brim, B. L.; Haskell, R.; Awedikian, R.; Ellinwood, N.M.; Jin, L.; Kumar, A.; Foster, T.C.; Magnusson, K.

    2012-01-01

    The GluN2B subunit of the N-methyl-D-aspartate (NMDA) receptor shows age-related declines in expression across the frontal cortex and hippocampus. This decline is strongly correlated to age-related memory declines. This study was designed to determine if increasing GluN2B subunit expression in the frontal lobe or hippocampus would improve memory in aged mice. Mice were injected bilaterally with either the GluN2B vector, containing cDNA specific for the GluN2B subunit and enhanced Green Fluorescent Protein (eGFP); a control vector or vehicle. Spatial memory, cognitive flexibility, and associative memory were assessed using the Morris water maze. Aged mice, with increased GluN2B subunit expression, exhibited improved long-term spatial memory, comparable to young mice. However, memory was rescued on different days in the Morris water maze; early for hippocampal GluN2B subunit enrichment and later for the frontal lobe. A higher concentration of the GluN2B antagonist, Ro 25-6981, was required to impair long-term spatial memory in aged mice with enhanced GluN2B expression, as compared to aged controls, suggesting there was an increase in the number of GluN2B-containing NMDA receptors. In addition, hippocampal slices from aged mice with increased GluN2B subunit expression exhibited enhanced NMDA receptor-mediated excitatory post-synaptic potentials (EPSP). Treatment with Ro 25-6981 showed that a greater proportion of the NMDA receptor-mediated EPSP was due to the GluN2B subunit in these animals, as compared to aged controls. These results suggest that increasing the production of the GluN2B subunit in aged animals enhances memory and synaptic transmission. Therapies that enhance GluN2B subunit expression within the aged brain may be useful for ameliorating age-related memory declines. PMID:23103326

  14. D-Serine Metabolism and Its Importance in Development of Dictyostelium discoideum

    PubMed Central

    Ito, Tomokazu; Hamauchi, Natsuki; Hagi, Taisuke; Morohashi, Naoya; Hemmi, Hisashi; Sato, Yukie G.; Saito, Tamao; Yoshimura, Tohru

    2018-01-01

    In mammals, D-Ser is synthesized by serine racemase (SR) and degraded by D-amino acid oxidase (DAO). D-Ser acts as an endogenous ligand for N-methyl-D-aspartate (NMDA)- and δ2 glutamate receptors, and is involved in brain functions such as learning and memory. Although SR homologs are highly conserved in eukaryotes, little is known about the significance of D-Ser in non-mammals. In contrast to mammals, the slime mold Dictyostelium discoideum genome encodes SR, DAO, and additionally D-Ser specific degradation enzyme D-Ser dehydratase (DSD), but not NMDA- and δ2 glutamate receptors. Here, we studied the significances of D-Ser and DSD in D. discoideum. Enzymatic assays demonstrated that DSD is 460- and 1,700-fold more active than DAO and SR, respectively, in degrading D-Ser. Moreover, in dsd-null cells D-Ser degradation activity is completely abolished. In fact, while in wild-type D. discoideum intracellular D-Ser levels were considerably low, dsd-null cells accumulated D-Ser. These results indicated that DSD but not DAO is the primary enzyme responsible for D-Ser decomposition in D. discoideum. We found that dsd-null cells exhibit delay in development and arrest at the early culmination stage. The efficiency of spore formation was considerably reduced in the mutant cells. These phenotypes were further pronounced by exogenous D-Ser but rescued by plasmid-borne expression of dsd. qRT-PCR analysis demonstrated that mRNA expression of key genes in the cAMP signaling relay is perturbed in the dsd knockout. Our data indicate novel roles for D-Ser and/or DSD in the regulation of cAMP signaling in the development processes of D. discoideum. PMID:29740415

  15. Identification of Novel 14-3-3 Residues That Are Critical for Isoform-specific Interaction with GluN2C to Regulate N-Methyl-d-aspartate (NMDA) Receptor Trafficking*

    PubMed Central

    Chung, Connie; Wu, Wei-Hua; Chen, Bo-Shiun

    2015-01-01

    The 14-3-3 family of proteins is widely distributed in the CNS where they are major regulators of essential neuronal functions. There are seven known mammalian 14-3-3 isoforms (ζ,, τ, ϵ, η, β, and σ), which generally function as adaptor proteins. Previously, we have demonstrated that 14-3-3ϵ isoform dynamically regulates forward trafficking of GluN2C-containing NMDA receptors (NMDARs) in cerebellar granule neurons, that when expressed on the surface, promotes neuronal survival following NMDA-induced excitotoxicity. Here, we report 14-3-3 isoform-specific binding and functional regulation of GluN2C. In particular, we show that GluN2C C-terminal domain (CTD) binds to all 14-3-3 isoforms except 14-3-3σ, and binding is dependent on GluN2C serine 1096 phosphorylation. Co-expression of 14-3-3 (ζ and ϵ) and GluN1/GluN2C promotes the forward delivery of receptors to the cell surface. We further identify novel residues serine 145, tyrosine 178, and cysteine 189 on α-helices 6, 7, and 8, respectively, within ζ-isoform as part of the GluN2C binding motif and independent of the canonical peptide binding groove. Mutation of these conserved residues abolishes GluN2C binding and has no functional effect on GluN2C trafficking. Reciprocal mutation of alanine 145, histidine 180, and isoleucine 191 on 14-3-3σ isoform promotes GluN2C binding and surface expression. Moreover, inhibiting endogenous 14-3-3 using a high-affinity peptide inhibitor, difopein, greatly diminishes GluN2C surface expression. Together, these findings highlight the isoform-specific structural and functional differences within the 14-3-3 family of proteins, which determine GluN2C binding and its essential role in targeting the receptor to the cell surface to facilitate glutamatergic neurotransmission. PMID:26229101

  16. Expression analysis in a rat psychosis model identifies novel candidate genes validated in a large case–control sample of schizophrenia

    PubMed Central

    Ingason, A; Giegling, I; Hartmann, A M; Genius, J; Konte, B; Friedl, M; Ripke, S; Sullivan, P F; St. Clair, D; Collier, D A; O'Donovan, M C; Mirnics, K; Rujescu, D

    2015-01-01

    Antagonists of the N-methyl-D-aspartate (NMDA)-type glutamate receptor induce psychosis in healthy individuals and exacerbate schizophrenia symptoms in patients. In this study we have produced an animal model of NMDA receptor hypofunction by chronically treating rats with low doses of the NMDA receptor antagonist MK-801. Subsequently, we performed an expression study and identified 20 genes showing altered expression in the brain of these rats compared with untreated animals. We then explored whether the human orthologs of these genes are associated with schizophrenia in the largest schizophrenia genome-wide association study published to date, and found evidence for association for 4 out of the 20 genes: SF3B1, FOXP1, DLG2 and VGLL4. Interestingly, three of these genes, FOXP1, SF3B1 and DLG2, have previously been implicated in neurodevelopmental disorders. PMID:26460480

  17. Expression analysis in a rat psychosis model identifies novel candidate genes validated in a large case-control sample of schizophrenia.

    PubMed

    Ingason, A; Giegling, I; Hartmann, A M; Genius, J; Konte, B; Friedl, M; Ripke, S; Sullivan, P F; St Clair, D; Collier, D A; O'Donovan, M C; Mirnics, K; Rujescu, D

    2015-10-13

    Antagonists of the N-methyl-D-aspartate (NMDA)-type glutamate receptor induce psychosis in healthy individuals and exacerbate schizophrenia symptoms in patients. In this study we have produced an animal model of NMDA receptor hypofunction by chronically treating rats with low doses of the NMDA receptor antagonist MK-801. Subsequently, we performed an expression study and identified 20 genes showing altered expression in the brain of these rats compared with untreated animals. We then explored whether the human orthologs of these genes are associated with schizophrenia in the largest schizophrenia genome-wide association study published to date, and found evidence for association for 4 out of the 20 genes: SF3B1, FOXP1, DLG2 and VGLL4. Interestingly, three of these genes, FOXP1, SF3B1 and DLG2, have previously been implicated in neurodevelopmental disorders.

  18. Effects of Ginkgo biloba extracts on NMDA-activated currents in acutely isolated hippocampal neurons of the rat.

    PubMed

    Li, Shao; Luo, Jie; Wang, Xi; Guan, Bing-Cai; Sun, Chang-Kai

    2011-01-01

    Ginkgo biloba extracts (GBE) have long been used as a traditional herbal medicine for treating central nervous system diseases and peripheral vascular diseases, but the underlying mechanisms have yet to be elucidated. Furthermore, traditional GBE is in the form of microsomes and only dissolves in organic solvents; its clinical applications have been greatly limited. Therefore, in the present study, nanometer GBE (nGBE) was prepared utilizing supercritical anti-solvent (SAS) upon CO(2) -supercritical fluid extraction (CO(2) -SPF). Using whole-cell patch clamp techniques, the effects of different preparations of GBE on N-methyl-D-aspartate (NMDA)-activated currents (I(NMDA) ) from acutely isolated rat hippocampal neurons were investigated and the difference in protective potency between nGBE and mGBE evaluated. The results showed that the inward current activated by NMDA could be depressed by mGBE and nGBE. The inhibitory rates were 40% ± 17% and 64% ± 15%, and the half-inhibition concentrations (IC(50) ) were 0.0210 ± 0.0055 and 0.0262 ± 0.0038 mg/mL, respectively. In comparison, the modulatory effect of nGBE (dissolved in extracellular solution) on NMDA-activated current was significantly greater than that of mGBE (dissolved in DMSO) (p < 0.05). This indicated that the modulatory effects of GBE on NMDA-activated current may contribute to the neuroprotective effects of GBE and the modulatory effect of nGBE on NMDA-activated current was greater than that of mGBE. Copyright © 2010 John Wiley & Sons, Ltd.

  19. Glutamate Delta-1 Receptor Regulates Metabotropic Glutamate Receptor 5 Signaling in the Hippocampus.

    PubMed

    Suryavanshi, Pratyush S; Gupta, Subhash C; Yadav, Roopali; Kesherwani, Varun; Liu, Jinxu; Dravid, Shashank M

    2016-08-01

    The delta family of ionotropic glutamate receptors consists of glutamate delta-1 (GluD1) and glutamate delta-2 receptors. We have previously shown that GluD1 knockout mice exhibit features of developmental delay, including impaired spine pruning and switch in the N-methyl-D-aspartate receptor subunit, which are relevant to autism and other neurodevelopmental disorders. Here, we identified a novel role of GluD1 in regulating metabotropic glutamate receptor 5 (mGlu5) signaling in the hippocampus. Immunohistochemical analysis demonstrated colocalization of mGlu5 with GluD1 punctas in the hippocampus. Additionally, GluD1 protein coimmunoprecipitated with mGlu5 in the hippocampal membrane fraction, as well as when overexpressed in human embryonic kidney 293 cells, demonstrating that GluD1 and mGlu5 may cooperate in a signaling complex. The interaction of mGlu5 with scaffold protein effector Homer, which regulates mechanistic target of rapamycin (mTOR) signaling, was abnormal both under basal conditions and in response to mGlu1/5 agonist (RS)-3,5-dihydroxyphenylglycine (DHPG) in GluD1 knockout mice. The basal levels of phosphorylated mTOR and protein kinase B, the signaling proteins downstream of mGlu5 activation, were higher in GluD1 knockout mice, and no further increase was induced by DHPG. We also observed higher basal protein translation and an absence of DHPG-induced increase in GluD1 knockout mice. In accordance with a role of mGlu5-mediated mTOR signaling in synaptic plasticity, DHPG-induced internalization of surface α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor subunits was impaired in the GluD1 knockout mice. These results demonstrate that GluD1 interacts with mGlu5, and loss of GluD1 impairs normal mGlu5 signaling potentially by dysregulating coupling to its effector. These studies identify a novel role of the enigmatic GluD1 subunit in hippocampal function. Copyright © 2016 by The American Society for Pharmacology and Experimental

  20. Importance of the GluN2B Carboxy-Terminal Domain for Enhancement of Social Memories

    ERIC Educational Resources Information Center

    Jacobs, Stephanie; Wei, Wei; Wang, Deheng; Tsien, Joe Z.

    2015-01-01

    The N-methyl-D-aspartate (NMDA) receptor is known to be necessary for many forms of learning and memory, including social recognition memory. Additionally, the GluN2 subunits are known to modulate multiple forms of memory, with a high GluN2A:GluN2B ratio leading to impairments in long-term memory, while a low GluN2A:GluN2B ratio enhances some…

  1. 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.

  2. Prenatal exposure to an NMDA receptor antagonist, MK-801 reduces density of parvalbumin-immunoreactive GABAergic neurons in the medial prefrontal cortex and enhances phencyclidine-induced hyperlocomotion but not behavioral sensitization to methamphetamine in postpubertal rats.

    PubMed

    Abekawa, Tomohiro; Ito, Koki; Nakagawa, Shin; Koyama, Tsukasa

    2007-06-01

    Neurodevelopmental deficits of parvalbumin-immunoreactive gamma-aminobutyric acid (GABA)ergic interneurons in prefrontal cortex have been reported in schizophrenia. Glutamate influences the proliferation of this type of interneuron by an N-methyl-D-aspartate (NMDA)-receptor-mediated mechanism. The present study hypothesized that prenatal blockade of NMDA receptors would disrupt GABAergic neurodevelopment, resulting in differences in effects on behavioral responses to a noncompetitive NMDA antagonist, phencyclidine (PCP), and a dopamine releaser, methamphetamine (METH). GABAergic neurons were immunohistochemically stained with parvalbumin antibody. Psychostimulant-induced hyperlocomotion was measured using an infrared sensor. Prenatal exposure (E15-E18) to the NMDA receptor antagonist MK-801 reduced the density of parvalbumin-immunoreactive neurons in rat medial prefrontal cortex on postnatal day 63 (P63) and enhanced PCP-induced hyperlocomotion but not the acute effects of METH on P63 or the development of behavioral sensitization. Prenatal exposure to MK-801 reduced the number of parvalbumin-immunoreactive neurons even on postnatal day 35 (P35) and did not enhance PCP-induced hyperlocomotion, the acute effects of METH on P35, or the development of behavioral sensitization to METH. These findings suggest that prenatal blockade of NMDA receptors disrupts GABAergic neurodevelopment in medial prefrontal cortex, and that this disruption of GABAergic development may be related to the enhancement of the locomotion-inducing effect of PCP in postpubertal but not juvenile offspring. GABAergic deficit is unrelated to the effects of METH. This GABAergic neurodevelopmental disruption and the enhanced PCP-induced hyperlocomotion in adult offspring prenatally exposed to MK-801 may prove useful as a new model of the neurodevelopmental process of pathogenesis of treatment-resistant schizophrenia via an NMDA-receptor-mediated hypoglutamatergic mechanism.

  3. Contribution of N-methyl-D-aspartate receptors to attention and episodic spatial memory during senescence

    PubMed Central

    Guidi, Michael; Rani, Asha; Karic, Semir; Severance, Barrett; Kumar, Ashok; Foster, Thomas C.

    2015-01-01

    A decrease in N-methyl-D-aspartate receptor (NMDAR) function is associated with age-related cognitive impairments. However, NMDAR antagonists are prescribed for cognitive decline associated with age-related neurodegenerative disease, raising questions as to the role of NMDAR activity in cognitive function during aging. The current studies examined effects of NMDAR blockade on cognitive task that are sensitive to aging. Young and middle-age rats were trained on the five-choice serial reaction time task (5-CSRTT) and challenged with MK-801 (0.025, 0.05, and 0.1 mg/kg or vehicle). Attention deficits were apparent in middle-age and performance of young and middle-age rats was enhanced for low doses of MK-801 (0.025 and 0.05). The beneficial effects on attention were reversed by the highest dose of MK-801. Older animals exhibited a delay-dependent impairment of episodic spatial memory examined on a delayed-matching to place water maze task. Similarly, a low dose of MK-801 (0.05 mg/kg) impaired performance with increasing delay and aged animals were more susceptible to disruption by NMDAR blockade. Despite MK-801 impairment of episodic spatial memory, MK-801 had minimal effects on spatial reference memory. Our results confirm that NMDARs contribute to rapidly acquired and flexible spatial memory and support the idea that a decline in NMDAR function contributes to the age-related impairments in cognition. PMID:26234588

  4. Contribution of N-methyl-D-aspartate receptors to attention and episodic spatial memory during senescence.

    PubMed

    Guidi, Michael; Rani, Asha; Karic, Semir; Severance, Barrett; Kumar, Ashok; Foster, Thomas C

    2015-11-01

    A decrease in N-methyl-D-aspartate receptor (NMDAR) function is associated with age-related cognitive impairments. However, NMDAR antagonists are prescribed for cognitive decline associated with age-related neurodegenerative disease, raising questions as to the role of NMDAR activity in cognitive function during aging. The current studies examined effects of NMDAR blockade on cognitive task that are sensitive to aging. Young and middle-age rats were trained on the five-choice serial reaction time task (5-CSRTT) and challenged with MK-801 (0.025, 0.05, and 0.1mg/kg or vehicle). Attention deficits were apparent in middle-age and performance of young and middle-age rats was enhanced for low doses of MK-801 (0.025 and 0.05). The beneficial effects on attention were reversed by the highest dose of MK-801. Older animals exhibited a delay-dependent impairment of episodic spatial memory examined on a delayed-matching to place water maze task. Similarly, a low dose of MK-801 (0.05mg/kg) impaired performance with increasing delay and aged animals were more susceptible to disruption by NMDAR blockade. Despite MK-801 impairment of episodic spatial memory, MK-801 had minimal effects on spatial reference memory. Our results confirm that NMDARs contribute to rapidly acquired and flexible spatial memory and support the idea that a decline in NMDAR function contributes to the age-related impairments in cognition. Copyright © 2015 Elsevier Inc. All rights reserved.

  5. The regulatory effect of electro-acupuncture on the expression of NMDA receptors in a SCI rat model.

    PubMed

    Tu, Wen-Zhan; Chen, Wen-Ci; Xia, Wan; He, Rong; Hu, Jie; Jiang, Ming-Chen; Jiang, Song-He

    2017-05-15

    In early spinal cord injury (SCI), glutamate receptors, including N-methyl-d-aspartate (NMDA) receptors (NMDARs), are over-stimulated by excessively released glutamate. The enhanced activity of NMDARs may cause cell death by overloading calcium (Ca 2+ ) into cells based on their high permeability to Ca 2+ . Studies in SCI animals have shown that treatment with electro-acupuncture (EA) is able to reduce cell death and to improve functional recovery. One possible mechanism of this neuroprotective effect is that EA has regulatory effect on NMDARs. To test whether EA could protect the spinal cord after SCI by decreasing the expression levels of NR1 and NR2A. We conducted EA treatment on a rat SCI model produced with a New York University (NYU) Impactor and measured hindlimb locomotor function by Basso, Beattie and Bresnahan Locomotor Rating Scale (BBB Scale). The expression of NR1 and NR2, the subunits of NMDARs, in the injured spinal cord was measured by Immunofluorescence stainings, western blot and real-time quantitative PCR (RT-qPCR). Our results showed that two days after the SCI the expression of NR1 and NR2 were dramatically enhanced at both protein and mNRA levels, which were significantly reduced by EA treatment at two specific acupoints, Dazhui (DU14) and Mingmen (DU4). EA is a potential therapeutic method for treating early SCI in human. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Myosin IIb-dependent Regulation of Actin Dynamics Is Required for N-Methyl-D-aspartate Receptor Trafficking during Synaptic Plasticity.

    PubMed

    Bu, Yunfei; Wang, Ning; Wang, Shaoli; Sheng, Tao; Tian, Tian; Chen, Linlin; Pan, Weiwei; Zhu, Minsheng; Luo, Jianhong; Lu, Wei

    2015-10-16

    N-Methyl-d-aspartate receptor (NMDAR) synaptic incorporation changes the number of NMDARs at synapses and is thus critical to various NMDAR-dependent brain functions. To date, the molecules involved in NMDAR trafficking and the underlying mechanisms are poorly understood. Here, we report that myosin IIb is an essential molecule in NMDAR synaptic incorporation during PKC- or θ burst stimulation-induced synaptic plasticity. Moreover, we demonstrate that myosin light chain kinase (MLCK)-dependent actin reorganization contributes to NMDAR trafficking. The findings from additional mutual occlusion experiments demonstrate that PKC and MLCK share a common signaling pathway in NMDAR-mediated synaptic regulation. Because myosin IIb is the primary substrate of MLCK and can regulate actin dynamics during synaptic plasticity, we propose that the MLCK- and myosin IIb-dependent regulation of actin dynamics is required for NMDAR trafficking during synaptic plasticity. This study provides important insights into a mechanical framework for understanding NMDAR trafficking associated with synaptic plasticity. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  7. Extrasynaptic targeting of NMDA receptors following D1 dopamine receptor activation and cocaine self-administration

    PubMed Central

    Ortinski, Pavel I.; Turner, Jill R.; Pierce, R. Christopher

    2013-01-01

    We previously showed that after repeated exposure to cocaine, D1-like dopamine receptor (D1DR) stimulation reverses plastic changes of AMPA receptor-mediated signaling in the nucleus accumbens shell. However, there is little information on the impact of cocaine self-administration on D1-NMDA receptor interactions in this brain region. Here, we assessed whether cocaine self-administration alters the effects of D1DR stimulation on synaptic and extrasynaptic NMDA receptors (NMDARs) using whole-cell patch-clamp recordings. In slices from cocaine-naïve rats, pre-treatment with a D1DR agonist decreased synaptic NMDAR receptor-mediated currents and increased the contribution of extrasynaptic NMDARs. In contrast, neither cocaine self-administration alone nor cocaine experience followed by D1DR stimulation had an effect on synaptic or extrasynaptic NMDAR signaling. Activation of extrasynaptic NMDARs relies on the availability of extracellular glutamate, which is regulated primarily by glutamate transporters. In cocaine-experienced animals, administration of a glutamate re-uptake blocker, DL-threo-β-benzyloxyaspartic acid (TBOA), revealed increased extrasynaptic NMDAR activity and stronger baseline activity of glutamate uptake transporters relative to cocaine-naïve rats. In cocaine-naïve rats, the D1DR-mediated increase in extrasynaptic NMDAR signaling was independent of the activity of glutamate re-uptake transporters. Taken together, these results indicate that cocaine experience blunts the influence of D1DRs on synaptic and extrasynaptic NMDAR signaling. Additionally, prior cocaine self-administration limits activation of the extrasynaptic NMDAR pool by increasing glutamate re-uptake. These findings outline a pattern of adaptive interactions between D1DRs and NMDARs in the nucleus accumbens shell and demonstrate up-regulation of extrasynaptic NMDAR signaling as a novel consequence of cocaine self-administration. PMID:23719812

  8. Regulation of dopamine D1 receptor dynamics within the postsynaptic density of hippocampal glutamate synapses.

    PubMed

    Ladepeche, Laurent; Yang, Luting; Bouchet, Delphine; Groc, Laurent

    2013-01-01

    Dopamine receptor potently modulates glutamate signalling, synaptic plasticity and neuronal network adaptations in various pathophysiological processes. Although key intracellular signalling cascades have been identified, the cellular mechanism by which dopamine and glutamate receptor-mediated signalling interplay at glutamate synapse remain poorly understood. Among the cellular mechanisms proposed to aggregate D1R in glutamate synapses, the direct interaction between D1R and the scaffold protein PSD95 or the direct interaction with the glutamate NMDA receptor (NMDAR) have been proposed. To tackle this question we here used high-resolution single nanoparticle imaging since it provides a powerful way to investigate at the sub-micron resolution the dynamic interaction between these partners in live synapses. We demonstrate in hippocampal neuronal networks that dopamine D1 receptors (D1R) laterally diffuse within glutamate synapses, in which their diffusion is reduced. Disrupting the interaction between D1R and PSD95, through genetical manipulation and competing peptide, did not affect D1R dynamics in glutamatergic synapses. However, preventing the physical interaction between D1R and the GluN1 subunit of NMDAR abolished the synaptic stabilization of diffusing D1R. Together, these data provide direct evidence that the interaction between D1R and NMDAR in synapses participate in the building of the dopamine-receptor-mediated signalling, and most likely to the glutamate-dopamine cross-talk.

  9. Protection by imidazol(ine) drugs and agmatine of glutamate-induced neurotoxicity in cultured cerebellar granule cells through blockade of NMDA receptor

    PubMed Central

    Olmos, Gabriel; DeGregorio-Rocasolano, Nuria; Regalado, M Paz; Gasull, Teresa; Boronat, M Assumpció; Trullas, Ramón; Villarroel, Alvaro; Lerma, Juan; García-Sevilla, Jesús A

    1999-01-01

    This study was designed to assess the potential neuroprotective effect of several imidazol(ine) drugs and agmatine on glutamate-induced necrosis and on apoptosis induced by low extracellular K+ in cultured cerebellar granule cells.Exposure (30 min) of energy deprived cells to L-glutamate (1–100 μM) caused a concentration-dependent neurotoxicity, as determined 24 h later by a decrease in the ability of the cells to metabolize 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide (MTT) into a reduced formazan product. L-glutamate-induced neurotoxicity (EC50=5 μM) was blocked by the specific NMDA receptor antagonist MK-801 (dizocilpine).Imidazol(ine) drugs and agmatine fully prevented neurotoxicity induced by 20 μM (EC100) L-glutamate with the rank order (EC50 in μM): antazoline (13)>cirazoline (44)>LSL 61122 [2-styryl-2-imidazoline] (54)>LSL 60101 [2-(2-benzofuranyl) imidazole] (75)>idazoxan (90)>LSL 60129 [2-(1,4-benzodioxan-6-yl)-4,5-dihydroimidazole] (101)>RX821002 (2-methoxy idazoxan) (106)>agmatine (196). No neuroprotective effect of these drugs was observed in a model of apoptotic neuronal cell death (reduction of extracellular K+) which does not involve stimulation of NMDA receptors.Imidazol(ine) drugs and agmatine fully inhibited [3H]-(+)-MK-801 binding to the phencyclidine site of NMDA receptors in rat brain. The profile of drug potency protecting against L-glutamate neurotoxicity correlated well (r=0.90) with the potency of the same compounds competing against [3H]-(+)-MK-801 binding.In HEK-293 cells transfected to express the NR1-1a and NR2C subunits of the NMDA receptor, antazoline and agmatine produced a voltage- and concentration-dependent block of glutamate-induced currents. Analysis of the voltage dependence of the block was consistent with the presence of a binding site for antazoline located within the NMDA channel pore with an IC50 of 10–12 μM at 0 mV.It is concluded that imidazol(ine) drugs and agmatine are

  10. The forced swimming-induced behavioural immobility response involves histone H3 phospho-acetylation and c-Fos induction in dentate gyrus granule neurons via activation of the N-methyl-D-aspartate/extracellular signal-regulated kinase/mitogen- and stress-activated kinase signalling pathway.

    PubMed

    Chandramohan, Yalini; Droste, Susanne K; Arthur, J Simon C; Reul, Johannes M H M

    2008-05-01

    The hippocampus is involved in learning and memory. Previously, we have shown that the acquisition of the behavioural immobility response after a forced swim experience is associated with chromatin modifications and transcriptional induction in dentate gyrus granule neurons. Given that both N-methyl-D-aspartate (NMDA) receptors and the extracellular signal-regulated kinases (ERK) 1/2 signalling pathway are involved in neuroplasticity processes underlying learning and memory, we investigated in rats and mice whether these signalling pathways regulate chromatin modifications and transcriptional events participating in the acquisition of the immobility response. We found that: (i) forced swimming evoked a transient increase in the number of phospho-acetylated histone H3-positive [P(Ser10)-Ac(Lys14)-H3(+)] neurons specifically in the middle and superficial aspects of the dentate gyrus granule cell layer; (ii) antagonism of NMDA receptors and inhibition of ERK1/2 signalling blocked forced swimming-induced histone H3 phospho-acetylation and the acquisition of the behavioural immobility response; (iii) double knockout (DKO) of the histone H3 kinase mitogen- and stress-activated kinases (MSK) 1/2 in mice completely abolished the forced swimming-induced increases in histone H3 phospho-acetylation and c-Fos induction in dentate granule neurons and the behavioural immobility response; (iv) blocking mineralocorticoid receptors, known not to be involved in behavioural immobility in the forced swim test, did not affect forced swimming-evoked histone H3 phospho-acetylation in dentate neurons; and (v) the pharmacological manipulations and gene deletions did not affect behaviour in the initial forced swim test. We conclude that the forced swimming-induced behavioural immobility response requires histone H3 phospho-acetylation and c-Fos induction in distinct dentate granule neurons through recruitment of the NMDA/ERK/MSK 1/2 pathway.

  11. Nodding syndrome in Tanzania may not be associated with circulating anti-NMDA-and anti-VGKC receptor antibodies or decreased pyridoxal phosphate serum levels-a pilot study.

    PubMed

    Dietmann, Anelia; Wallner, Bernd; König, Rebekka; Friedrich, Katrin; Pfausler, Bettina; Deisenhammer, Florian; Griesmacher, Andrea; Seger, Christoph; Matuja, William; JilekAall, Louise; Winkler, Andrea S; Schmutzhard, Erich

    2014-06-01

    Nodding syndrome (NS) is a seemingly progressive epilepsy disorder of unknown underlying cause. We investigated association of pyridoxal-phosphate serum levels and occurrence of anti-neuronal antibodies against N-methyl-D-aspartate (NMDA) receptor and voltage gated potassium channel (VGKC) complex in NS patients. Sera of a Tanzanian cohort of epilepsy and NS patients and community controls were tested for the presence of anti-NMDA-receptor and anti-VGKC complex antibodies by indirect immunofluorescence assay. Furthermore pyridoxal-phosphate levels were measured. Auto-antibodies against NMDA receptor or VGKC (LG1 or Caspr2) complex were not detected in sera of patients suffering from NS (n=6), NS plus other seizure types (n=16), primary generalized epilepsy (n=1) and community controls without epilepsy (n=7). Median Pyridoxal-phosphate levels in patients with NS compared to patients with primary generalized seizures and community controls were not significantly different. However, these median pyridoxal-phosphate levels are significantly lower compared to the range considered normal in Europeans. In this pilot study NS was not associated with serum anti-NMDA receptor or anti-VGKC complex antibodies and no association to pyridoxal-phosphate serum levels was found.

  12. CXCL13 regulates the trafficking of GluN2B-containing NMDA receptor via IL-17 in the development of remifentanil-induced hyperalgesia in rats.

    PubMed

    Zhu, M; Yuan, S T; Yu, W L; Jia, L L; Sun, Y

    2017-05-01

    This study aimed to investigate whether CXCL13 modulated the trafficking of NMDA receptor via interleukin (IL)-17 in a rat model of remifentanil-induced hyperalgesia (RIH).Although chemokines are crucial regulators of neuroinflammation, spinal N-methyl-d-aspartate (NMDA) receptor activation, and development of hypernociceptive process, little is known about specific pathogenesis and effective treatment. Inflammatory mediators are required for excitatory synaptic transmission in pathologic pain. A neutralizing antibody against CXCL13 (anti-CXCL13), antiserum against IL-17 (anti-IL-17), and recombinant CXCL13 and IL-17 were administered intrathecally to explore the roles of CXCL13, IL-17, and NMDA receptor, as well as the prevention of hyperalgesia. Paw withdrawal threshold and paw withdrawal latency were employed to record mechanical allodynia and thermal hyperalgesia. Reverse transcriptase quantitative polymerase chain reaction was used to evaluate the levels of CXCL13/CXCR5 and IL-17/IL-17RA in the spinal dorsal horn. The trafficking of spinal GluN2B-containing NMDA receptor was assessed by Western blot after nociceptive testing. This study found mechanical allodynia and thermal hyperalgesia with a remarkable increase in the expression of spinal CXCL13/CXCR5 and IL-17/IL-17RA and trafficking of GluN2B-containing NMDA receptor after remifentanil exposure. Behavioral RIH and elevated GluN2B trafficking were dampened by intrathecal anti-CXCL13 and anti-IL-17, respectively. The delivery of exogenous CXCL13 dose-dependently generated a rapid nociceptive hypersensitivity in naïve rats, which was prevented by coadministering anti-IL-17. CXCL13-induced IL-17RA overproduction and GluN2B trafficking were reversed by anti-IL-17 treatment. GluN2B antagonist also blocked CXCL13, and IL-17 directly induced hyperalgesia. This study highlighted the contribution of IL-17 pathway in the trafficking of CXCL13-induced GluN2B-containing NMDA receptor in the pathogenesis of RIH

  13. [The role of non-NMDA glutamate receptors in the EEG effects of chronic administration of noopept GVS-111 in awake rats].

    PubMed

    Kovalev, G I; Vorob'ev, V V

    2002-01-01

    Participation of the non-NMDA glutamate receptor subtype in the formation of the EEG frequency spectrum was studied in wakeful rats upon a long-term (10 x 0.2 mg/kg, s.c.) administration of the nootropic dipeptide GVS-111 (noopept or N-phenylacetyl-L-prolyglycine ethylate). The EEGs were measured with electrodes implanted into somatosensor cortex regions, hippocampus, and a cannula in the lateral ventricle. The acute reactions (characteristic of nootropes) in the alpha and beta ranges of EEG exhibited inversion after the 6th injection of noopept and almost completely vanished after the 9th injection. Preliminary introduction of the non-NMDA antagonist GDEE (glutamic acid diethyl ester) in a dose of 1 mumole into the lateral ventricle restored the EEG pattern observed upon the 6th dose of GVS-111. The role of glutamate receptors in the course of a prolonged administration of nootropes, as well as the possible mechanisms accounting for a difference in the action of GVS-111 and piracetam are discussed.

  14. Involvement of pre- and postsynaptic NMDA receptors at local circuit interneuron connections in rat neocortex

    PubMed Central

    De-May, C.L.; Ali, A.B.

    2013-01-01

    To investigate the involvement of N-Methyl-D-aspartate (NMDA) receptors in local neocortical synaptic transmission, dual whole-cell recordings – combined with biocytin labelling – were obtained from bitufted adapting, multipolar adapting or multipolar non-adapting interneurons and pyramidal cells in layers II–V of rat (postnatal days 17–22) sensorimotor cortex. The voltage dependency of the amplitude of Excitatory postsynaptic potentials (EPSPs) received by the three types of interneuron appeared to coincide with the interneuron subclass; upon depolarisation, EPSPs received by multipolar non-adapting interneurons either decreased in amplitude or appeared insensitive, multipolar adapting interneuron EPSP amplitudes increased or appeared insensitive, whereas bitufted interneuron EPSP amplitudes increased or decreased. Connections were challenged with the NMDA receptor antagonist d-(−)-2-amino-5-phosphonopentanoic acid (d-AP5) (50 μM) revealing NMDA receptors to contribute to EPSPs received by all cell types, this also abolished the non-conventional voltage dependency. Reciprocal connections were frequent between pyramidal cells and multipolar interneurons, and inhibitory postsynaptic potentials (IPSPs) elicited in pyramidal cells by both multipolar adapting and multipolar non-adapting interneurons were sensitive to a significant reduction in amplitude by d-AP5. The involvement of presynaptic NMDA receptors was indicated by coefficient of variation analysis and an increase in the failures of transmission. Furthermore, by loading MK-801 into the pre- or postsynaptic neurons, we observed that a reduction in inhibition requires presynaptic and not postsynaptic NMDA receptors. These results suggest that NMDA receptors possess pre- and postsynaptic roles at selective neocortical synapses that are probably important in governing spike-timing and information flow. PMID:23079623

  15. Effect of memantine on cue-induced alcohol craving in recovering alcohol-dependent patients.

    PubMed

    Krupitsky, Evgeny M; Neznanova, Olga; Masalov, Dimitry; Burakov, Andrey M; Didenko, Tatyana; Romanova, Tatyana; Tsoy, Marina; Bespalov, Anton; Slavina, Tatyana Y; Grinenko, Alexander A; Petrakis, Ismene L; Pittman, Brian; Gueorguieva, Ralitza; Zvartau, Edwin E; Krystal, John H

    2007-03-01

    Ethanol blocks N-methyl-d-aspartic acid (NMDA) glutamate receptors. Increased NMDA receptor function may contribute to motivational disturbances that contribute to alcoholism. The authors assessed whether the NMDA receptor antagonist memantine reduces cue-induced alcohol craving and produces ethanol-like subjective effects. Thirty-eight alcohol-dependent inpatients participated in three daylong testing sessions in a randomized order under double-blind conditions. On each test day, subjects received 20 mg of memantine, 40 mg of memantine, or placebo, and subjective responses to treatment were assessed. The level of alcohol craving was assessed before and after exposure to an alcohol cue. Memantine did not stimulate alcohol craving before exposure to an alcohol cue, and it attenuated alcohol cue-induced craving in a dose-related fashion. It produced dose-related ethanol-like effects without adverse cognitive or behavioral effects. These data support further exploration of whether well-tolerated NMDA receptor antagonists might have a role in the treatment of alcoholism.

  16. Distinct presynaptic regulation of dopamine release through NMDA receptors in striosome- and matrix-enriched areas of the rat striatum

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Krebs, M.O.; Trovero, F.; Desban, M.

    1991-05-01

    Striosome- and matrix-enriched striatal zones were defined in coronal and sagittal brain sections of the rat, on the basis of {sup 3}H-naloxone binding to mu-opiate receptors (a striosome-specific marker). Then, using a new in vitro microsuperfusion device, the NMDA (50 microM)-evoked release of newly synthesized {sup 3}H-dopamine ({sup 3}H-DA) was examined in these four striatal areas under Mg(2+)-free conditions. The amplitudes of the responses were different in striosomal (171 +/- 6% and 161 +/- 5% of the spontaneous release) than in matrix areas (223 +/- 6% and 248 +/- 12%), even when glycine (1 or 100 microM) was coapplied (inmore » the presence of 1 microM strychnine). In the four areas, the NMDA-evoked release of {sup 3}H-DA was blocked completely by Mg{sup 2}{sup +} (1 mM) or (+)-5-methyl-10,11-dihydro-5H-dibenzo(a,d)cyclohepten-5,10-imine maleate (MK-801; 1 microM) and almost totally abolished by kynurenate (100 microM). Because the tetrodotoxin (TTX)-resistant NMDA-evoked release of {sup 3}H-DA was similar in striosome- (148 +/- 5% and 152 +/- 6%) or matrix-enriched (161 +/- 5% and 156 +/- 7%) areas, the indirect (TTX-sensitive) component of NMDA-evoked responses, which involves striatal neurons and/or afferent fibers, seems more important in the matrix- than in the striosome-enriched areas. The modulation of DA release by cortical glutamate and/or aspartate-containing inputs through NMDA receptors in the matrix appears thus to be partly distinct from that observed in the striosomes, providing some functional basis for the histochemical striatal heterogeneity.« less

  17. Crystal Structures of the Glutamate Receptor Ion Channel GluK3 and GluK5 Amino-Terminal Domains

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kumar, Janesh; Mayer, Mark L.

    2010-11-30

    Ionotropic glutamate receptors (iGluRs) mediate the majority of fast excitatory synaptic neurotransmission in the central nervous system. The selective assembly of iGluRs into AMPA, kainate, and N-methyl-d-aspartic acid (NMDA) receptor subtypes is regulated by their extracellular amino-terminal domains (ATDs). Kainate receptors are further classified into low-affinity receptor families (GluK1-GluK3) and high-affinity receptor families (GluK4-GluK5) based on their affinity for the neurotoxin kainic acid. These two families share a 42% sequence identity for the intact receptor but only a 27% sequence identity at the level of ATD. We have determined for the first time the high-resolution crystal structures of GluK3 andmore » GluK5 ATDs, both of which crystallize as dimers but with a strikingly different dimer assembly at the R1 interface. By contrast, for both GluK3 and GluK5, the R2 domain dimer assembly is similar to those reported previously for other non-NMDA iGluRs. This observation is consistent with the reports that GluK4-GluK5 cannot form functional homomeric ion channels and require obligate coassembly with GluK1-GluK3. Our analysis also reveals that the relative orientation of domains R1 and R2 in individual non-NMDA receptor ATDs varies by up to 10{sup o}, in contrast to the 50{sup o} difference reported for the NMDA receptor GluN2B subunit. This restricted domain movement in non-NMDA receptor ATDs seems to result both from extensive intramolecular contacts between domain R1 and domain R2 and from their assembly as dimers, which interact at both R1 and R2 domains. Our results provide the first insights into the structure and function of GluK4-GluK5, the least understood family of iGluRs.« less

  18. Atypical cleavage of protonated N-fatty acyl amino acids derived from aspartic acid evidenced by sequential MS3 experiments.

    PubMed

    Boukerche, Toufik Taalibi; Alves, Sandra; Le Faouder, Pauline; Warnet, Anna; Bertrand-Michel, Justine; Bouchekara, Mohamed; Belbachir, Mohammed; Tabet, Jean-Claude

    2016-12-01

    Lipidomics calls for information on detected lipids and conjugates whose structural elucidation by mass spectrometry requires to rationalization of their gas phase dissociations toward collision-induced dissociation (CID) processes. This study focused on activated dissociations of two lipoamino acid (LAA) systems composed of N-palmitoyl acyl coupled with aspartic and glutamic acid mono ethyl esters (as LAA (*D) and LAA (*E) ). Although in MS/MS, their CID spectra show similar trends, e.g., release of water and ethanol, the [(LAA (*D/*E) +H)-C 2 H 5 OH] + product ions dissociate via distinct pathways in sequential MS 3 experiments. The formation of all the product ions is rationalized by charge-promoted cleavages often involving stepwise processes with ion isomerization into ion-dipole prior to dissociation. The latter explains the maleic anhydride or ketene neutral losses from N-palmitoyl acyl aspartate and glutamate anhydride fragment ions, respectively. Consequently, protonated palmitoyl acid amide is generated from LAA (*D), whereas LAA (*E) leads to the [*E+H-H 2 O] + anhydride. The former releases ammonia to provide acylium, which gives the C n H (2n-1) and C n H (2n-3) carbenium series. This should offer structural information, e.g., to locate either unsaturation(s) or alkyl group branching present on the various fatty acyl moieties of lipo-aspartic acid in further studies based on MS n experiments.

  19. Computationally Discovered Potentiating Role of Glycans on NMDA Receptors

    NASA Astrophysics Data System (ADS)

    Sinitskiy, Anton V.; Stanley, Nathaniel H.; Hackos, David H.; Hanson, Jesse E.; Sellers, Benjamin D.; Pande, Vijay S.

    2017-04-01

    N-methyl-D-aspartate receptors (NMDARs) are glycoproteins in the brain central to learning and memory. The effects of glycosylation on the structure and dynamics of NMDARs are largely unknown. In this work, we use extensive molecular dynamics simulations of GluN1 and GluN2B ligand binding domains (LBDs) of NMDARs to investigate these effects. Our simulations predict that intra-domain interactions involving the glycan attached to residue GluN1-N440 stabilize closed-clamshell conformations of the GluN1 LBD. The glycan on GluN2B-N688 shows a similar, though weaker, effect. Based on these results, and assuming the transferability of the results of LBD simulations to the full receptor, we predict that glycans at GluN1-N440 might play a potentiator role in NMDARs. To validate this prediction, we perform electrophysiological analysis of full-length NMDARs with a glycosylation-preventing GluN1-N440Q mutation, and demonstrate an increase in the glycine EC50 value. Overall, our results suggest an intramolecular potentiating role of glycans on NMDA receptors.

  20. Need for Better Diabetes Treatment: The Therapeutic Potential of NMDA Receptor Antagonists.

    PubMed

    Welters, A; Lammert, E; Mayatepek, E; Meissner, T

    2017-01-01

    Diabetes mellitus is the most common metabolic disorder in children and adolescents. Optimal control of blood glucose concentration is essential to prevent acute and diabetic long-term complications. The options to treat diabetes have clearly improved over the last decades, however, to date neither type 1 diabetes nor type 2 diabetes mellitus can be cured. Therefore, diabetes research aims at developing β-cell protective agents that prevent or even reverse diabetes onset. N-methyl-D-aspartate receptors (NMDARs) are glutamate-gated ion channels that are widely expressed in the central nervous system (CNS) where they hold central roles in CNS function. NMDAR dysfunction is associated with several neurological and psychiatric disorders and therefore NMDAR modulators have several potential therapeutic indications. Only little is known about the role of pancreatic NMDA receptors. Our data provide evidence that inhibition of pancreatic NMDARs, either genetically or pharmacologically with the over-the-counter drug dextromethorphan, increases glucose-stimulated insulin secretion from mouse and human pancreatic islets, improves glucose tolerance in mice and individuals with diabetes and promotes islet cell survival under diabetogenic conditions. Thus, our data indicate for the first time that NMDAR antagonists could serve as adjunct treatment for diabetes mellitus. The development of a safe, blood glucose lowering and particularly β-cell protective medication would significantly enhance current diabetes treatment. © Georg Thieme Verlag KG Stuttgart · New York.

  1. Characterization of postsynaptic calcium signals in the pyramidal neurons of anterior cingulate cortex

    PubMed Central

    Li, Xu-Hui; Song, Qian; Chen, Tao; Zhuo, Min

    2017-01-01

    Calcium signaling is critical for synaptic transmission and plasticity. N-methyl-D-aspartic acid (NMDA) receptors play a key role in synaptic potentiation in the anterior cingulate cortex. Most previous studies of calcium signaling focus on hippocampal neurons, little is known about the activity-induced calcium signals in the anterior cingulate cortex. In the present study, we show that NMDA receptor-mediated postsynaptic calcium signals induced by different synaptic stimulation in anterior cingulate cortex pyramidal neurons. Single and multi-action potentials evoked significant suprathreshold Ca2+ increases in somas and spines. Both NMDA receptors and voltage-gated calcium channels contributed to this increase. Postsynaptic Ca2+signals were induced by puff-application of glutamate, and a NMDA receptor antagonist AP5 blocked these signals in both somas and spines. Finally, long-term potentiation inducing protocols triggered postsynaptic Ca2+ influx, and these influx were NMDA receptor dependent. Our results provide the first study of calcium signals in the anterior cingulate cortex and demonstrate that NMDA receptors play important roles in postsynaptic calcium signals in anterior cingulate cortex pyramidal neurons. PMID:28726541

  2. HD iPSC-derived neural progenitors accumulate in culture and are susceptible to BDNF withdrawal due to glutamate toxicity

    PubMed Central

    Mattis, Virginia B.; Tom, Colton; Akimov, Sergey; Saeedian, Jasmine; Østergaard, Michael E.; Southwell, Amber L.; Doty, Crystal N.; Ornelas, Loren; Sahabian, Anais; Lenaeus, Lindsay; Mandefro, Berhan; Sareen, Dhruv; Arjomand, Jamshid; Hayden, Michael R.; Ross, Christopher A.; Svendsen, Clive N.

    2015-01-01

    Huntington's disease (HD) is a fatal neurodegenerative disease, caused by expansion of polyglutamine repeats in the Huntingtin gene, with longer expansions leading to earlier ages of onset. The HD iPSC Consortium has recently reported a new in vitro model of HD based on the generation of induced pluripotent stem cells (iPSCs) from HD patients and controls. The current study has furthered the disease in a dish model of HD by generating new non-integrating HD and control iPSC lines. Both HD and control iPSC lines can be efficiently differentiated into neurons/glia; however, the HD-derived cells maintained a significantly greater number of nestin-expressing neural progenitor cells compared with control cells. This cell population showed enhanced vulnerability to brain-derived neurotrophic factor (BDNF) withdrawal in the juvenile-onset HD (JHD) lines, which appeared to be CAG repeat-dependent and mediated by the loss of signaling from the TrkB receptor. It was postulated that this increased death following BDNF withdrawal may be due to glutamate toxicity, as the N-methyl-d-aspartate (NMDA) receptor subunit NR2B was up-regulated in the cultures. Indeed, blocking glutamate signaling, not just through the NMDA but also mGlu and AMPA/Kainate receptors, completely reversed the cell death phenotype. This study suggests that the pathogenesis of JHD may involve in part a population of ‘persistent’ neural progenitors that are selectively vulnerable to BDNF withdrawal. Similar results were seen in adult hippocampal-derived neural progenitors isolated from the BACHD model mouse. Together, these results provide important insight into HD mechanisms at early developmental time points, which may suggest novel approaches to HD therapeutics. PMID:25740845

  3. Enhanced pre-synaptic glutamate release in deep-dorsal horn contributes to calcium channel alpha-2-delta-1 protein-mediated spinal sensitization and behavioral hypersensitivity

    PubMed Central

    Nguyen, David; Deng, Ping; Matthews, Elizabeth A; Kim, Doo-Sik; Feng, Guoping; Dickenson, Anthony H; Xu, Zao C; Luo, Z David

    2009-01-01

    Nerve injury-induced expression of the spinal calcium channel alpha-2-delta-1 subunit (Cavα2δ1) has been shown to mediate behavioral hypersensitivity through a yet identified mechanism. We examined if this neuroplasticity modulates behavioral hypersensitivity by regulating spinal glutamatergic neurotransmission in injury-free transgenic mice overexpressing the Cavα2δ1 proteins in neuronal tissues. The transgenic mice exhibited hypersensitivity to mechanical stimulation (allodynia) similar to the spinal nerve ligation injury model. Intrathecally delivered antagonists for N-methyl-D-aspartate (NMDA) and α-amino-3-hydroxyl-5-methylisoxazole-4-propionic acid (AMPA)/kainate receptors, but not for the metabotropic glutamate receptors, caused a dose-dependent allodynia reversal in the transgenic mice without changing the behavioral sensitivity in wild-type mice. This suggests that elevated spinal Cavα2δ1 mediates allodynia through a pathway involving activation of selective glutamate receptors. To determine if this is mediated by enhanced spinal neuronal excitability or pre-synaptic glutamate release in deep-dorsal horn, we examined wide-dynamic-range (WDR) neuron excitability with extracellular recording and glutamate-mediated excitatory postsynaptic currents with whole-cell patch recording in deep-dorsal horn of the Cavα2δ1 transgenic mice. Our data indicated that overexpression of Cavα2δ1 in neuronal tissues led to increased frequency, but not amplitude, of miniature excitatory post synaptic currents mediated mainly by AMPA/kainate receptors at physiological membrane potentials, and also by NMDA receptors upon depolarization, without changing the excitability of WDR neurons to high intensity stimulation. Together, these findings support a mechanism of Cavα2δ1-mediated spinal sensitization in which elevated Cavα2δ1 causes increased pre-synaptic glutamate release that leads to reduced excitation thresholds of post-synaptic dorsal horn neurons to innocuous

  4. Different Classes of Glutamate Receptors Mediate Distinct Behaviors in a Single Brainstem Nucleus

    NASA Astrophysics Data System (ADS)

    Dye, John; Heiligenberg, Walter; Keller, Clifford H.; Kawasaki, Masashi

    1989-11-01

    We have taken advantage of the increasing understanding of glutamate neuropharmacology to probe mechanisms of well-defined vertebrate behaviors. Here we report a set of experiments that suggests distinct roles for two major classes of glutamate receptors in a discrete premotor nucleus of the brainstem. The medullary pacemaker nucleus of weakly electric fish is an endogenous oscillator that controls the electric organ discharge (EOD). Its regular frequency of firing is modulated during several distinct behaviors. The pacemaker nucleus continues firing regularly when isolated in vitro, and modulatory behaviors can be reproduced by stimulating the descending input pathway. Glutamate agonists applied to the pacemaker in vitro produced increases in frequency, while glutamate antagonists selectively blocked stimulus-induced modulations. Experiments with glutamate antagonists in the intact animal resulted in specific effects on two well-characterized behaviors. Our data indicate that these behaviors are separately mediated in the pacemaker by receptors displaying characteristics of the kainate/quisqualate and N-methyl-D-aspartate subtypes of glutamate receptor, respectively.

  5. Glycine Potentiates AMPA Receptor Function through Metabotropic Activation of GluN2A-Containing NMDA Receptors

    PubMed Central

    Li, Li-Jun; Hu, Rong; Lujan, Brendan; Chen, Juan; Zhang, Jian-Jian; Nakano, Yasuko; Cui, Tian-Yuan; Liao, Ming-Xia; Chen, Jin-Cao; Man, Heng-Ye; Feng, Hua; Wan, Qi

    2016-01-01

    NMDA receptors are Ca2+-permeable ion channels. The activation of NMDA receptors requires agonist glutamate and co-agonist glycine. Recent evidence indicates that NMDA receptor also has metabotropic function. Here we report that in cultured mouse hippocampal neurons, glycine increases AMPA receptor-mediated currents independent of the channel activity of NMDA receptors and the activation of glycine receptors. The potentiation of AMPA receptor function by glycine is antagonized by the inhibition of ERK1/2. In the hippocampal neurons and in the HEK293 cells transfected with different combinations of NMDA receptors, glycine preferentially acts on GluN2A-containing NMDA receptors (GluN2ARs), but not GluN2B-containing NMDA receptors (GluN2BRs), to enhance ERK1/2 phosphorylation independent of the channel activity of GluN2ARs. Without requiring the channel activity of GluN2ARs, glycine increases AMPA receptor-mediated currents through GluN2ARs. Thus, these results reveal a metabotropic function of GluN2ARs in mediating glycine-induced potentiation of AMPA receptor function via ERK1/2 activation. PMID:27807405

  6. Sustained neuronal activity generated by glial plasticity

    PubMed Central

    Pirttimaki, Tiina M.; Hall, Stephen D.; Parri, H. Rheinallt

    2011-01-01

    Astrocytes release gliotransmitters, notably glutamate, that can affect neuronal and synaptic activity. In particular, astrocytic glutamate release results in the generation of N-methyl D-aspartate receptor (NMDA-R) mediated slow inward currents (SICs) in neurons. However, factors underlying the emergence of SICs, and their physiological roles are largely unknown. Here we show that, in acute slices of rat somatosensory thalamus, stimulation of Lemniscal or cortical afferents results in a sustained increase of SICs in thalamocortical (TC) neurons that outlasts the duration of the stimulus by an hour. This long term enhancement (LTE) of astrocytic glutamate release is induced by group I metabotropic glutamate receptors (mGluRs), and is dependent on astrocytic intracellular calcium ([Ca2+]i). Neuronal SICs are mediated by extrasynaptic NR2B subunit-containing NMDA-Rs and are capable of eliciting bursts. These are distinct from T-type Ca2+ channel dependent bursts of action potentials, and are synchronized in neighboring TC neurons. These findings describe a previously unrecognized form of excitatory, non-synaptic plasticity in the central nervous system (CNS) that feeds forward to generate local neuronal firing long after stimulus termination. PMID:21613477

  7. Neurosteroid binding to the amino terminal and glutamate binding domains of ionotropic glutamate receptors.

    PubMed

    Cameron, Krasnodara; Bartle, Emily; Roark, Ryan; Fanelli, David; Pham, Melissa; Pollard, Beth; Borkowski, Brian; Rhoads, Sarah; Kim, Joon; Rocha, Monica; Kahlson, Martha; Kangala, Melinda; Gentile, Lisa

    2012-06-01

    The endogenous neurosteroids, pregnenolone sulfate (PS) and 3α-hydroxy-5β-pregnan-20-one sulfate (PREGAS), have been shown to differentially regulate the ionotropic glutamate receptor (iGluR) family of ligand-gated ion channels. Upon binding to these receptors, PREGAS decreases current flow through the channels. Upon binding to non-NMDA or NMDA receptors containing an GluN2C or GluN2D subunit, PS also decreases current flow through the channels, however, upon binding to NMDA receptors containing an GluN2A or GluN2B subunit, flow through the channels increases. To begin to understand this differential regulation, we have cloned the S1S2 and amino terminal domains (ATD) of the NMDA GluN2B and GluN2D and AMPA GluA2 subunits. Here we present results that show that PS and PREGAS bind to different sites in the ATD of the GluA2 subunit, which when combined with previous results from our lab, now identifies two binding domains for each neurosteroid. We also show both neurosteroids bind only to the ATD of the GluN2D subunit, suggesting that this binding is distinct from that of the AMPA GluA2 subunit, with both leading to iGluR inhibition. Finally, we provide evidence that both PS and PREGAS bind to the S1S2 domain of the NMDA GluN2B subunit. Neurosteroid binding to the S1S2 domain of NMDA subunits responsible for potentiation of iGluRs and to the ATD of NMDA subunits responsible for inhibition of iGluRs, provides an interesting option for therapeutic design. Copyright © 2012 Elsevier Inc. All rights reserved.

  8. Gelidium amansii promotes dendritic spine morphology and synaptogenesis, and modulates NMDA receptor-mediated postsynaptic current.

    PubMed

    Hannan, Md Abdul; Mohibbullah, Md; Hong, Yong-Ki; Nam, Joo Hyun; Moon, Il Soo

    2014-01-01

    Neurotrophic factors are essential for the differentiation and maturation of developing neurons as well as providing survival support to the mature neurons. Moreover, therapeutically neurotrophic factors are promising to reconstruct partially damaged neuronal networks in neurodegenerative diseases. In the previous study, we reported that the ethanol extract of an edible marine alga, Gelidium amansii (GAE) had shown promising effects in the development and maturation of both axon and dendrites of hippocampal neurons. Here, we demonstrate that in primary culture of hippocampal neurons (1) GAE promotes a significant increase in the number of filopodia and dendritic spines; (2) promotes synaptogenesis; (3) enhances N-methyl-D-aspartic acid (NMDA) receptor recruitment; and (4) modulates NMDA-receptor-mediated postsynaptic current. Taken together these findings that GAE might be involved in both morphological and functional maturation of neurons suggest the possibility that GAE may constitute a promising candidate for novel compounds for the prevention and treatment of neurodegenerative diseases.

  9. Antidepressant action of ketamine via mTOR is mediated by inhibition of nitrergic Rheb degradation.

    PubMed

    Harraz, M M; Tyagi, R; Cortés, P; Snyder, S H

    2016-03-01

    As traditional antidepressants act only after weeks/months, the discovery that ketamine, an antagonist of glutamate/N-methyl-D-aspartate (NMDA) receptors, elicits antidepressant actions in hours has been transformative. Its mechanism of action has been elusive, though enhanced mammalian target of rapamycin (mTOR) signaling is a major feature. We report a novel signaling pathway wherein NMDA receptor activation stimulates generation of nitric oxide (NO), which S-nitrosylates glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Nitrosylated GAPDH complexes with the ubiquitin-E3-ligase Siah1 and Rheb, a small G protein that activates mTOR. Siah1 degrades Rheb leading to reduced mTOR signaling, while ketamine, conversely, stabilizes Rheb that enhances mTOR signaling. Drugs selectively targeting components of this pathway may offer novel approaches to the treatment of depression.

  10. Genetic differences in NMDA and D1 receptor levels, and operant responding for food and morphine in Lewis and Fischer 344 rats.

    PubMed

    Martín, Sonsoles; Lyupina, Yulia; Crespo, José Antonio; González, Begoña; García-Lecumberri, Carmen; Ambrosio, Emilio

    2003-05-30

    Previously, we have shown that Lewis (LEW) rats acquire faster than Fischer 344 (F344) rats operant food- and morphine-reinforced tasks under fixed-ratio schedules of reinforcement. The first purpose of the present work has been to study if differences in operant responding behavior may participate in the reported differences in morphine self-administration behavior between both inbred rat strains. To this end, we have analyzed the microstructure of responding obtained under a variable-interval (VI) of food reinforcement by calculating the inter-response time (IRT) for each rat strain. LEW rats exhibited shorter IRTs than F344 rats, suggesting that LEW rats may have an inherent high or compulsive operant responding activity. When subjects of both inbred rat strains were submitted to a schedule of morphine reinforcement of high responding requirements such as progressive ratio schedules, LEW rats also reached significantly higher breaking points and final response ratio than F344 rats for i.v. morphine self-administration. Given that there are neurochemical differences between both rat strains and that glutamatergic N-methyl-D-aspartate (NMDA) and dopaminergic D(1) receptors have been involved in operant responding behavior, a second purpose of this work has been to measure basal NMDA and D(1) receptor levels in these rat strains by quantitative receptor autoradiography. Compared to F344 rats, LEW rats showed higher basal NMDA receptor levels in frontal and cingulate cortex, caudate putamen, central amygdaloid nuclei, and intermediate white layer of superior colliculus, and higher basal D(1) receptor levels in several areas of hippocampus and thalamus, and substantia nigra pars reticulata. Taken together, these results suggest that an inherent high operant responding activity of LEW rats may have a role in the previous reported faster acquisition of opiate-reinforced behavior in operant self-administration paradigms under fixed-ratio schedules of reinforcement. In

  11. Alterations in brain extracellular dopamine and glycine levels following combined administration of the glycine transporter type-1 inhibitor Org-24461 and risperidone.

    PubMed

    Nagy, Katalin; Marko, Bernadett; Zsilla, Gabriella; Matyus, Peter; Pallagi, Katalin; Szabo, Geza; Juranyi, Zsolt; Barkoczy, Jozsef; Levay, Gyorgy; Harsing, Laszlo G

    2010-12-01

    The most dominant hypotheses for the pathogenesis of schizophrenia have focused primarily upon hyperfunctional dopaminergic and hypofunctional glutamatergic neurotransmission in the central nervous system. The therapeutic efficacy of all atypical antipsychotics is explained in part by antagonism of the dopaminergic neurotransmission, mainly by blockade of D(2) dopamine receptors. N-methyl-D-aspartate (NMDA) receptor hypofunction in schizophrenia can be reversed by glycine transporter type-1 (GlyT-1) inhibitors, which regulate glycine concentrations at the vicinity of NMDA receptors. Combined drug administration with D(2) dopamine receptor blockade and activation of hypofunctional NMDA receptors may be needed for a more effective treatment of positive and negative symptoms and the accompanied cognitive deficit in schizophrenia. To investigate this type of combined drug administration, rats were treated with the atypical antipsychotic risperidone together with the GlyT-1 inhibitor Org-24461. Brain microdialysis was applied in the striatum of conscious rats and determinations of extracellular dopamine, DOPAC, HVA, glycine, glutamate, and serine concentrations were carried out using HPLC/electrochemistry. Risperidone increased extracellular concentrations of dopamine but failed to influence those of glycine or glutamate measured in microdialysis samples. Org-24461 injection reduced extracellular dopamine concentrations and elevated extracellular glycine levels but the concentrations of serine and glutamate were not changed. When risperidone and Org-24461 were added in combination, a decrease in extracellular dopamine concentrations was accompanied with sustained elevation of extracellular glycine levels. Interestingly, the extracellular concentrations of glutamate were also enhanced. Our data indicate that coadministration of an antipsychotic with a GlyT-1 inhibitor may normalize hypofunctional NMDA receptor-mediated glutamatergic neurotransmission with reduced

  12. A novel missense mutation in GRIN2A causes a nonepileptic neurodevelopmental disorder.

    PubMed

    Fernández-Marmiesse, Ana; Kusumoto, Hirofumi; Rekarte, Saray; Roca, Iria; Zhang, Jin; Myers, Scott J; Traynelis, Stephen F; Couce, Mª Luz; Gutierrez-Solana, Luis; Yuan, Hongjie

    2018-04-11

    Mutations in the GRIN2A gene, which encodes the GluN2A (glutamate [NMDA] receptor subunit epsilon-1) subunit of the N-methyl-d-aspartate receptor, have been identified in patients with epilepsy-aphasia spectrum disorders, idiopathic focal epilepsies with centrotemporal spikes, and epileptic encephalopathies with severe developmental delay. However, thus far, mutations in this gene have not been associated with a nonepileptic neurodevelopmental disorder with dystonia. The objective of this study was to identify the disease-causing gene in 2 siblings with neurodevelopmental and movement disorders with no epileptiform abnormalities. The study method was targeted next-generation sequencing panel for neuropediatric disorders and subsequent electrophysiological studies. The 2 siblings carry a novel missense mutation in the GRIN2A gene (p.Ala643Asp) that was not detected in genomic DNA isolated from blood cells of their parents, suggesting that the mutation is the consequence of germinal mosaicism in 1 progenitor. In functional studies, the GluN2A-A643D mutation increased the potency of the agonists L-glutamate and glycine and decreased the potency of endogenous negative modulators, including protons, magnesium and zinc but reduced agonist-evoked peak current response in mammalian cells, suggesting that this mutation has a mixed effect on N-methyl-d-aspartate receptor function. De novo GRIN2A mutations can give rise to a neurodevelopmental and movement disorder without epilepsy. © 2018 International Parkinson and Movement Disorder Society. © 2018 International Parkinson and Movement Disorder Society.

  13. Testing synaptic plasticity in dynamic mate choice decisions: N-methyl d-aspartate receptor blockade disrupts female preference

    PubMed Central

    Ramsey, Mary E.; Vu, Wendy; Cummings, Molly E.

    2014-01-01

    Social behaviours such as mate choice require context-specific responses, often with evolutionary consequences. Increasing evidence indicates that the behavioural plasticity associated with mate choice involves learning. For example, poeciliids show age-dependent changes in female preference functions and express synaptic-plasticity-associated molecular markers during mate choice. Here, we test whether social cognition is necessary for female preference behaviour by blocking the central player in synaptic plasticity, NMDAR (N-methyl d-aspartate receptor), in a poeciliid fish, Xiphophorus nigrensis. After subchronic exposure to NMDAR antagonist MK-801, female preference behaviours towards males were dramatically reduced. Overall activity levels were unaffected, but there was a directional shift from ‘social’ behaviours towards neutral activity. Multivariate gene expression patterns significantly discriminated between females with normal versus disrupted plasticity processes and correlated with preference behaviours—not general activity. Furthermore, molecular patterns support a distinction between ‘preference’ (e.g. neuroserpin, neuroligin-3, NMDAR) and ‘sociality’ (isotocin and vasotocin) gene clusters, highlighting a possible conservation between NMDAR disruption and nonapeptides in modulating behaviour. Our results suggest that mate preference may involve greater social memory processing than overall sociality, and that poeciliid preference functions integrate synaptic-plasticity-oriented ‘preference’ pathways with overall sociality to invoke dynamic, context-specific responses towards favoured males and away from unfavoured males. PMID:24807251

  14. Involvement of NMDA receptors in the antidepressant-like effect of tramadol in the mouse forced swimming test.

    PubMed

    Ostadhadi, Sattar; Norouzi-Javidan, Abbas; Chamanara, Mohsen; Akbarian, Reyhaneh; Imran-Khan, Muhammad; Ghasemi, Mehdi; Dehpour, Ahmad-Reza

    2017-09-01

    Tramadol is an analgesic agent that is mainly used to treat moderate to severe pain. There is evidence that tramadol may have antidepressant property. However, the mechanisms underlying the antidepressant effects of tramadol have not been elucidated yet. Considering that fact that N-methyl-d-aspartate (NMDA) receptor signaling may play an important role in the pathophysiology of depression, the aim of the present study was to investigate the role of NMDA receptor signaling in the possible antidepressant-like effects of tramadol in the mouse forced swimming test (mFST). We found that tramadol exerted antidepressant-like effects at high dose (40mg/kg, intraperitoneally [i.p.]) in the mFST. Co-administration of non-effective doses of NMDA receptor antagonists (ketamine [1mg/kg, i.p.], MK-801 [0.05mg/kg, i.p.], or magnesium sulfate [10mg/kg, i.p.]) with sub-effective dose of tramadol (20mg/kg, i.p.) exerted significant antidepressant-like effects in the mFST. The antidepressant-like effects of tramadol (40mg/kg) was also inhibited by pre-treatment with non-effective dose of the NMDA receptor agonist NMDA (75mg/kg, i.p.). Our data suggest a role for NMDA receptor signaling in the antidepressant-like effects of tramadol in the mFST. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Involvement of ventral tegmental area ionotropic glutamate receptors in the expression of ethanol-induced conditioned place preference.

    PubMed

    Pina, Melanie M; Cunningham, Christopher L

    2016-10-15

    The ventral tegmental area (VTA) is a well-established neural substrate of reward-related processes. Activity within this structure is increased by the primary and conditioned rewarding effects of abused drugs and its engagement is heavily reliant on excitatory input from structures upstream. In the case of drug seeking, it is thought that exposure to drug-associated cues engages glutamatergic VTA afferents that signal directly to dopamine cells, thereby triggering this behavior. It is unclear, however, whether glutamate input to VTA is directly involved in ethanol-associated cue seeking. Here, the role of intra-VTA ionotropic glutamate receptor (iGluR) signaling in ethanol-cue seeking was evaluated in DBA/2J mice using an ethanol conditioned place preference (CPP) procedure. Intra-VTA iGluRs α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPAR)/kainate and N-methyl-d-aspartate (NMDAR) were blocked during ethanol CPP expression by co-infusion of antagonist drugs 6,7-dinitroquinoxaline-2,3-dione (DNQX; AMPA/kainate) and d-(-)-2-Amino-5-phosphonopentanoic acid (AP5; NMDA). Compared to aCSF, bilateral infusion of low (1 DNQX+100 AP5ng/side) and high (5 DNQX+500 AP5ng/side) doses of the AMPAR and NMDAR antagonist cocktail into VTA blocked ethanol CPP expression. This effect was site specific, as DNQX/AP5 infusion proximal to VTA did not significantly impact CPP expression. An increase in activity was found at the high but not low dose of DNQX/AP5. These findings demonstrate that activation of iGluRs within the VTA is necessary for ethanol-associated cue seeking, as measured by CPP. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. NMDA and AMPA receptors in the anterior cingulate cortex mediates visceral pain in visceral hypersensitivity rats.

    PubMed

    Zhou, Lin; Huang, Junjing; Gao, Jun; Zhang, Guanpo; Jiang, Jinjin

    2014-02-01

    Several studies have shown that N-methyl-D-aspartate (NMDA)-receptor activation in anterior cingulate cortex (ACC) neurons plays critical roles in modulating visceral pain responses in visceral hypersensitivity (VH) rats. However, there are few reports about the expressions of NMDA and α-amino-3-hydroxy-5-methyl-4-isox-azolepropionic-acid (AMPA) receptor subtypes in ACC of VH model rats at different time points. The current study was undertaken to investigate NR2A, NR2B and GluR2 expressions in ACC of VH rats that were induced by administration with 5% mustard oil. Our results indicated that NR2B, but not NR2A, was highly expressed in VH model group on day 15, 22, and 36 compared with normal group (p < 0.05). GluR2 expression was also higher in VH model group on day 15, 22, and 36 than that of normal group (p < 0.05). These findings suggested increased expression of NR2B and GluR2 might be key mechanisms for long-term synaptic plastic changes in VH rats. Copyright © 2014. Published by Elsevier Inc.

  17. Timosaponin derivative YY-23 acts as a non-competitive NMDA receptor antagonist and exerts a rapid antidepressant-like effect in mice.

    PubMed

    Zhang, Qi; Guo, Fei; Fu, Zhi-wen; Zhang, Bing; Huang, Cheng-gang; Li, Yang

    2016-02-01

    N-methyl-D-aspartic acid (NMDA) receptor modulators have shown promising results as potential antidepressant agents, whereas timosaponins extracted from the Chinese herb Rhizoma Anemarrhenae exhibit antidepressant activities. In the present study we examined whether YY-23, a modified metabolite of timosaponin B-III, could affect NMDA receptors in rat hippocampal neurons in vitro, and evaluated its antidepressant-like effects in stressed mice. NMDA-induced currents were recorded in acutely dissociated rat hippocampal CA1 neurons using a whole-cell recording technique. C57BL/6 mice were exposed to a 6-week chronic mild stress (CMS) or a 10-d chronic social defeat stress (CSDS). The stressed mice were treated with YY-23 (20 mg·kg(-1)·d(-1)) or a positive-control drug, fluoxetine (10 mg·kg(-1)·d(-1)) for 3 weeks. Behavioral assessments were carried out every week. In acutely dissociated rat hippocampal CA1 neurons, YY-23 selectively and reversibly inhibited NMDA-induced currents with an EC50 value of 2.8 μmol/L. This inhibition of NMDA-induced currents by YY-23 was non-competitive, and had no features of voltage-dependency or use-dependency. Treatment of the stressed mice with YY-23 not only reversed CMS-induced deficiency of sucrose preference and immobility time, and CSDS-induced reduction of social interaction, but also had faster onset as compared to fluoxetine. YY-23 is a novel non-competitive antagonist of NMDA receptors with promising rapid antidepressant-like effects in mouse models of CMS and CSDS depression.

  18. Temporal Dynamics of Antidepressant Ketamine Effects on Glutamine Cycling Follow Regional Fingerprints of AMPA and NMDA Receptor Densities.

    PubMed

    Li, Meng; Demenescu, Liliana Ramona; Colic, Lejla; Metzger, Coraline Danielle; Heinze, Hans-Jochen; Steiner, Johann; Speck, Oliver; Fejtova, Anna; Salvadore, Giacomo; Walter, Martin

    2017-05-01

    The anterior cingulate cortex (ACC) has shown decreased glutamate levels in patients with major depressive disorder. Subanesthetic doses of ketamine were repeatedly shown to improve depressive symptoms within 24 h after infusion and this antidepressant effect was attributed to increased α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate (AMPA) throughput. To elucidate ketamine's mechanism of action, we tested whether the clinical time course of the improvement is mirrored by the change of glutamine/glutamate ratio and if such effects show a regional and temporal specificity in two distinct subdivisions of ACC with different AMPA/N-methyl-D-aspartate receptor profiles. In a double-blind, placebo-controlled intravenous infusion study of ketamine, we measured glutamate and glutamine in the pregenual ACC (pgACC) and the anterior midcingulate cortex at 1 and 24 h post infusion with magnetic resonance spectroscopy at 7 T. A significant interaction of time, region, and treatment was found for the glutamine/glutamate ratios (placebo, n=14; ketamine, n=12). Post-hoc analyses revealed that the glutamine/glutamate ratio increased significantly in the ketamine group, compared with placebo, specifically in the pgACC after 24 h. The glutamine/glutamate increase in the pgACC caused by ketamine at 24 h post infusion was reproduced in an enlarged sample (placebo, n=24; ketamine, n=20). Our results support a significant temporal and regional response in glutamine/glutamate ratios to a single subanesthetic dose of ketamine, which mirrors the time course of the antidepressant response and reversal of the molecular deficits in patients and which may be associated with the histoarchitectonical receptor fingerprints of the ACC subregions.

  19. Temporal Dynamics of Antidepressant Ketamine Effects on Glutamine Cycling Follow Regional Fingerprints of AMPA and NMDA Receptor Densities

    PubMed Central

    Li, Meng; Demenescu, Liliana Ramona; Colic, Lejla; Metzger, Coraline Danielle; Heinze, Hans-Jochen; Steiner, Johann; Speck, Oliver; Fejtova, Anna; Salvadore, Giacomo; Walter, Martin

    2017-01-01

    The anterior cingulate cortex (ACC) has shown decreased glutamate levels in patients with major depressive disorder. Subanesthetic doses of ketamine were repeatedly shown to improve depressive symptoms within 24 h after infusion and this antidepressant effect was attributed to increased α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate (AMPA) throughput. To elucidate ketamine's mechanism of action, we tested whether the clinical time course of the improvement is mirrored by the change of glutamine/glutamate ratio and if such effects show a regional and temporal specificity in two distinct subdivisions of ACC with different AMPA/N-methyl-D-aspartate receptor profiles. In a double-blind, placebo-controlled intravenous infusion study of ketamine, we measured glutamate and glutamine in the pregenual ACC (pgACC) and the anterior midcingulate cortex at 1 and 24 h post infusion with magnetic resonance spectroscopy at 7 T. A significant interaction of time, region, and treatment was found for the glutamine/glutamate ratios (placebo, n=14; ketamine, n=12). Post-hoc analyses revealed that the glutamine/glutamate ratio increased significantly in the ketamine group, compared with placebo, specifically in the pgACC after 24 h. The glutamine/glutamate increase in the pgACC caused by ketamine at 24 h post infusion was reproduced in an enlarged sample (placebo, n=24; ketamine, n=20). Our results support a significant temporal and regional response in glutamine/glutamate ratios to a single subanesthetic dose of ketamine, which mirrors the time course of the antidepressant response and reversal of the molecular deficits in patients and which may be associated with the histoarchitectonical receptor fingerprints of the ACC subregions. PMID:27604568

  20. Essential role of GluD1 in dendritic spine development and GluN2B to GluN2A NMDAR subunit switch in the cortex and hippocampus reveals ability of GluN2B inhibition in correcting hyperconnectivity.

    PubMed

    Gupta, Subhash C; Yadav, Roopali; Pavuluri, Ratnamala; Morley, Barbara J; Stairs, Dustin J; Dravid, Shashank M

    2015-06-01

    The glutamate delta-1 (GluD1) receptor is highly expressed in the forebrain. We have previously shown that loss of GluD1 leads to social and cognitive deficits in mice, however, its role in synaptic development and neurotransmission remains poorly understood. Here we report that GluD1 is enriched in the medial prefrontal cortex (mPFC) and GluD1 knockout mice exhibit a higher dendritic spine number, greater excitatory neurotransmission as well as higher number of synapses in mPFC. In addition abnormalities in the LIMK1-cofilin signaling, which regulates spine dynamics, and a lower ratio of GluN2A/GluN2B expression was observed in the mPFC in GluD1 knockout mice. Analysis of the GluD1 knockout CA1 hippocampus similarly indicated the presence of higher spine number and synapses and altered LIMK1-cofilin signaling. We found that systemic administration of an N-methyl-d-aspartate (NMDA) receptor partial agonist d-cycloserine (DCS) at a high-dose, but not at a low-dose, and a GluN2B-selective inhibitor Ro-25-6981 partially normalized the abnormalities in LIMK1-cofilin signaling and reduced excess spine number in mPFC and hippocampus. The molecular effects of high-dose DCS and GluN2B inhibitor correlated with their ability to reduce the higher stereotyped behavior and depression-like behavior in GluD1 knockout mice. Together these findings demonstrate a critical requirement for GluD1 in normal spine development in the cortex and hippocampus. Moreover, these results identify inhibition of GluN2B-containing receptors as a mechanism for reducing excess dendritic spines and stereotyped behavior which may have therapeutic value in certain neurodevelopmental disorders such as autism. Copyright © 2015 Elsevier Ltd. All rights reserved.