Competitive Inhibition at the Glycine Site of the N-Methyl-d-aspartate Receptor by the Anesthetics Xenon and Isoflurane: Evidence from Molecular Modeling and Electrophysiology

Background:Inhibition of N-methyl-d-aspartate (NMDA) receptors by anesthetic gases and vapors may play an important role in anesthesia and neuroprotection. However, the site of action of these agents on the NMDA receptor is unknown. The authors show that xenon and isoflurane compete for the binding of the coagonist glycine on the NMDA receptor NR1 subunit. Methods:Using a novel application of grand canonical Monte Carlo simulations, the authors predict the binding site of xenon on NMDA receptors. They test this prediction using electrophysiology on recombinant NMDA receptors. Results:The authors’ modeling predicts that xenon binds at the glycine site of the NMDA receptor. The authors show that inhibition of NMDA receptors by xenon and isoflurane increases as glycine concentration is decreased, consistent with the prediction of competitive inhibition at the glycine site. Lineweaver-Burk analysis shows that isoflurane inhibition seems purely competitive with glycine, but for xenon, there is an additional component of noncompetitive inhibition. The loss of inhibitory effect of xenon and isoflurane in mutant NR1(F639A)/NR2A receptors is explained by increased glycine affinity of the mutant receptors, and inhibition is restored at low glycine concentrations. Conclusions:Xenon and isoflurane inhibit NMDA receptors by binding at the same site as the coagonist glycine. This finding may have important implications for general anesthesia and neuroprotection. Neuroprotectants that act at the glycine site of the NMDA receptor antagonists are well tolerated in patients, being devoid of psychotomimetic side effects, and the mechanism of inhibition may play a role in their clinical profile.

[1]  R. Harris,et al.  Effects of Anesthetics on Mutant N-Methyl-d-Aspartate Receptors Expressed in Xenopus Oocytes , 2006, Journal of Pharmacology and Experimental Therapeutics.

[2]  P. Bickler,et al.  Isoflurane Neuroprotection in Rat Hippocampal Slices Decreases with Aging: Changes in Intracellular Ca2+ Regulation and N-methyl-d-aspartate Receptor–mediated Ca2+ Influx , 2006, Anesthesiology.

[3]  E. Eger,et al.  Differential Modulation of Human N-Methyl-d-Aspartate Receptors by Structurally Diverse General Anesthetics , 2006, Anesthesia and analgesia.

[4]  T. González-Hernández,et al.  Glycine release in the substantia nigra: Interaction with glutamate and GABA , 2006, Neuropharmacology.

[5]  M. Mayer,et al.  Crystal Structures of the Kainate Receptor GluR5 Ligand Binding Core Dimer with Novel GluR5-Selective Antagonists , 2006, The Journal of Neuroscience.

[6]  G. Westbrook,et al.  Synaptic and extrasynaptic NMDA receptor NR2 subunits in cultured hippocampal neurons. , 2006, Journal of neurophysiology.

[7]  N. Franks,et al.  Molecular targets underlying general anaesthesia , 2006, British journal of pharmacology.

[8]  Matthew Clark,et al.  Grand Canonical Monte Carlo Simulation of Ligand-Protein Binding , 2006, J. Chem. Inf. Model..

[9]  W. R. Lieb,et al.  Two-pore-domain K+ channels are a novel target for the anesthetic gases xenon, nitrous oxide, and cyclopropane. , 2004, Molecular pharmacology.

[10]  Eric Gouaux,et al.  Mechanisms of activation, inhibition and specificity: crystal structures of the NMDA receptor NR1 ligand‐binding core , 2003, The EMBO journal.

[11]  Jérôme Chave,et al.  Cluster Analysis of Spatial Patterns in Malaysian Tree Species , 2002, The American Naturalist.

[12]  M. Maze,et al.  Effects of Xenon on In Vitro and In Vivo Models of Neuronal Injury , 2002, Anesthesiology.

[13]  W. R. Lieb,et al.  Determinants of the Anesthetic Sensitivity of Neuronal Nicotinic Acetylcholine Receptors* , 2002, The Journal of Biological Chemistry.

[14]  Thomas W Vickroy,et al.  In vivo monitoring of amino acids by direct sampling of brain extracellular fluid at ultralow flow rates and capillary electrophoresis , 2002, Journal of Neuroscience Methods.

[15]  J. Woodward,et al.  Ethanol Inhibition ofN-Methyl-d-aspartate Receptors Is Reduced by Site-directed Mutagenesis of a Transmembrane Domain Phenylalanine Residue* , 2001, The Journal of Biological Chemistry.

[16]  Berend Smit,et al.  Understanding Molecular Simulation , 2001 .

[17]  E. Bertaccini,et al.  Anesthetics and ion channels: molecular models and sites of action. , 2001, Annual review of pharmacology and toxicology.

[18]  M. Hollmann,et al.  Modulation of NMDA Receptor Function by Ketamine and Magnesium. Part II: Interactions with Volatile Anesthetics , 2001, Anesthesia and analgesia.

[19]  T. Yamakura,et al.  Effects of Gaseous Anesthetics Nitrous Oxide and Xenon on Ligand-gated Ion Channels: Comparison with Isoflurane and Ethanol , 2000, Anesthesiology.

[20]  B. Matthews,et al.  Size versus polarizability in protein-ligand interactions: binding of noble gases within engineered cavities in phage T4 lysozyme. , 2000, Journal of molecular biology.

[21]  Jie Yang,et al.  COMPASS Force Field for 14 Inorganic Molecules, He, Ne, Ar, Kr, Xe, H2, O2, N2, NO, CO, CO2, NO2, CS2, and SO2, in Liquid Phases , 2000 .

[22]  Nicholas P. Franks,et al.  Contrasting Synaptic Actions of the Inhalational General Anesthetics Isoflurane and Xenon , 2000, Anesthesiology.

[23]  M. MacIver,et al.  Excitatory Synaptic Transmission Mediated by NMDA Receptors Is More Sensitive to Isoflurane than Are Non-NMDA Receptor-mediated Responses , 2000, Anesthesiology.

[24]  N. Harrison,et al.  General anaesthetic actions on ligand-gated ion channels , 1999, Cellular and Molecular Life Sciences CMLS.

[25]  K. Lees,et al.  Safety and tolerability of GV150526 (a glycine site antagonist at the N-methyl-D-aspartate receptor) in patients with acute stroke. , 1999, Stroke.

[26]  R. Dingledine,et al.  The glutamate receptor ion channels. , 1999, Pharmacological reviews.

[27]  P. Ascher,et al.  Glycine uptake governs glycine site occupancy at NMDA receptors of excitatory synapses. , 1998, Journal of neurophysiology.

[28]  R. Dickinson,et al.  How does xenon produce anaesthesia? , 1998, Nature.

[29]  R. Harris,et al.  Sites of alcohol and volatile anaesthetic action on GABAA and glycine receptors , 1997, Nature.

[30]  V. Malashkevich,et al.  The Crystal Structure of a Five-Stranded Coiled Coil in COMP: A Prototype Ion Channel? , 1996, Science.

[31]  M Mezei,et al.  Grand canonical ensemble Monte Carlo simulation of the dCpG/proflavine crystal hydrate. , 1996, Biophysical journal.

[32]  A C Hall,et al.  Effects of inhalational general anaesthetics on native glycine receptors in rat medullary neurones and recombinant glycine receptors in Xenopus oocytes , 1996, British journal of pharmacology.

[33]  W. R. Lieb,et al.  Temperature Dependence of the Potency of Volatile General Anesthetics: Implications for In Vitro Experiments , 1996, Anesthesiology.

[34]  J. Woodward,et al.  Ethanol sensitivity of heteromeric NMDA receptors: Effects of subunit assembly, glycine and NMDAR1 Mg2+-insensitive mutants , 1995, Neuropharmacology.

[35]  D. Monaghan,et al.  Glycine modulates ethanol inhibition of heteromeric N-methyl-D-aspartate receptors expressed in Xenopus oocytes. , 1995, Molecular pharmacology.

[36]  L. Buck,et al.  Effects of lsoflurane and Hypothermia on Glutamate Receptor-mediated Calcium Influx in Brain Slices , 1994, Anesthesiology.

[37]  Y. Jan,et al.  Changing subunit composition of heteromeric NMDA receptors during development of rat cortex , 1994, Nature.

[38]  W. R. Lieb,et al.  Molecular and cellular mechanisms of general anaesthesia , 1994, Nature.

[39]  F. F. Weight,et al.  Ethanol inhibition of N-methyl-d-aspartate-activated ion current in rat hippocampal neurons is not competitive with glycine , 1992, Brain Research.

[40]  B. Tabakoff,et al.  Glycine site-directed agonists reverse the actions of ethanol at the N-methyl-D-aspartate receptor. , 1990, Molecular pharmacology.

[41]  S. Curry,et al.  Effects of general anesthetics on the bacterial luciferase enzyme from Vibrio harveyi: an anesthetic target site with differential sensitivity. , 1990, Biochemistry.

[42]  N. P. Franks,et al.  Do general anaesthetics act by competitive binding to specific receptors? , 1984, Nature.

[43]  W. Cleland,et al.  Statistical analysis of enzyme kinetic data. , 2006, Methods in enzymology.