An NMDA receptor/nitric oxide cascade is involved in cerebellar LTD but is not localized to the parallel fiber terminal.

Long-term depression (LTD) of the parallel fiber-Purkinje cell synapse in the cerebellum is a cellular model system that has been suggested to underlie certain forms of motor learning. Induction of cerebellar LTD requires a postsynaptic kinase limb involving activation of mGluR1, protein kinase Calpha (PKCalpha), and phosphorylation of ser-880 on the AMPA receptor subunit GluR2. Several lines of evidence have also implicated a complementary phosphatase limb in which N-methyl-d-aspartate (NMDA) receptor-mediated Ca(2+) influx activates neuronal nitric oxide synthase (nNOS), the ultimate consequences of which are mediated by nitric oxide (NO), cGMP, and inhibition of postsynaptic protein phosphatases. However, the cellular localization of an NMDA/NO cascade has been complicated by the fact that neither functional NMDA receptors nor nNOS are expressed in Purkinje cells. This has lead to a proposal in which NMDA receptors activate nNOS in parallel fibers. Here, we confirm that pharmacological blockade of NMDA receptor or NO signaling blocks induction of LTD. However, no evidence was found for functional NMDA receptors in parallel fiber terminals: blockade of NMDA receptors did not alter either presynaptic Ca(2+) transients or the frequency of miniature excitatory postsynaptic currents. NMDA receptor blockade did abolish a slow depolarization evoked by burst stimulation of parallel fiber-stellate cell synapses. The application of NMDA evoked a Ca(2+) transient in stellate cell terminals but not in parallel fiber terminals. These results are consistent with the hypothesis that an NMDA receptor/NO cascade involved in cerebellar LTD is localized to interneurons rather than parallel fibers.

[1]  J. Garthwaite,et al.  Synaptic activation of metabotropic glutamate receptors in the parallel Fibre-Purkinje cell pathway in rat cerebellar slices , 1994, Neuroscience.

[2]  K. Shibuki,et al.  Endogenous nitric oxide release required for long-term synaptic depression in the cerebellum , 1991, Nature.

[3]  M. Ito,et al.  Messengers mediating long-term desensitization in cerebellar Purkinje cells. , 1990, Neuroreport.

[4]  D. Linden.  From Molecules to Memory in the Cerebellum , 2003, Science.

[5]  D. Bredt,et al.  PSD-93 Knock-Out Mice Reveal That Neuronal MAGUKs Are Not Required for Development or Function of Parallel Fiber Synapses in Cerebellum , 2001, The Journal of Neuroscience.

[6]  M. Ito,et al.  Protein phosphatase 2A inhibition induces cerebellar long-term depression and declustering of synaptic AMPA receptor. , 2004, Proceedings of the National Academy of Sciences of the United States of America.

[7]  Masao Ito,et al.  Long-lasting depression of parallel fiber-Purkinje cell transmission induced by conjunctive stimulation of parallel fibers and climbing fibers in the cerebellar cortex , 1982, Neuroscience Letters.

[8]  S. Nakanishi,et al.  Differential expression of five N‐methyl‐D‐aspartate receptor subunit mRNAs in the cerebellum of developing and adult rats , 1994, The Journal of comparative neurology.

[9]  A. Marty,et al.  Presynaptic Effects of NMDA in Cerebellar Purkinje Cells and Interneurons , 1999, The Journal of Neuroscience.

[10]  M H Ellisman,et al.  Absence of cerebellar long-term depression in mice lacking neuronal nitric oxide synthase. , 1997, Learning & memory.

[11]  R. Huganir,et al.  Requirement of AMPA Receptor GluR2 Phosphorylation for Cerebellar Long-Term Depression , 2003, Science.

[12]  E. D’Angelo,et al.  Beyond parallel fiber LTD: the diversity of synaptic and non-synaptic plasticity in the cerebellum , 2001, Nature Neuroscience.

[13]  A. Bordey,et al.  Glial Glutamate Transporters Limit Spillover Activation of Presynaptic NMDA Receptors and Influence Synaptic Inhibition of Purkinje Neurons , 2004, The Journal of Neuroscience.

[14]  B. Clark,et al.  Activity-Dependent Recruitment of Extrasynaptic NMDA Receptor Activation at an AMPA Receptor-Only Synapse , 2002, The Journal of Neuroscience.

[15]  M. Ito,et al.  Cerebellar long-term depression. , 1996, Trends in neurosciences.

[16]  F. Crépel,et al.  Synapses between parallel fibres and stellate cells express long‐term changes in synaptic efficacy in rat cerebellum , 2004, The Journal of physiology.

[17]  D. Linden.  Neuroscience. From molecules to memory in the cerebellum. , 2003, Science.

[18]  D. Linden,et al.  A Unique PDZ Ligand in PKCα Confers Induction of Cerebellar Long-Term Synaptic Depression , 2004, Neuron.

[19]  P. J. Sjöström,et al.  Neocortical LTD via Coincident Activation of Presynaptic NMDA and Cannabinoid Receptors , 2003, Neuron.

[20]  W G Regehr,et al.  Calcium transients in cerebellar granule cell presynaptic terminals. , 1995, Biophysical journal.

[21]  N. Hartell.  cGMP acts within cerebellar Purkinje cells to produce long term depression via mechanisms involving PKC and PKG. , 1994, Neuroreport.

[22]  M. Dickinson,et al.  A long-term depression of AMPA currents in cultured cerebellar purkinje neurons , 1991, Neuron.

[23]  Joseph P. Yuan,et al.  Activation of the TRPC1 cation channel by metabotropic glutamate receptor mGluR1 , 2003, Nature.

[24]  F. Crépel,et al.  Receptors and Second Messengers Involved in Long‐term Depression in Rat Cerebellar Slices In Vitro: a Reappraisal , 1995, The European journal of neuroscience.

[25]  D. Linden,et al.  Cerebellar Long-Term Synaptic Depression Requires PKC-Mediated Activation of CPI-17, a Myosin/Moesin Phosphatase Inhibitor , 2002, Neuron.

[26]  Philippe Isope,et al.  Involvement of Presynaptic N-Methyl-D-Aspartate Receptors in Cerebellar Long-Term Depression , 2002, Neuron.

[27]  Ian Duguid,et al.  Retrograde activation of presynaptic NMDA receptors enhances GABA release at cerebellar interneuron–Purkinje cell synapses , 2004, Nature Neuroscience.

[28]  H. Kimura,et al.  Histochemical mapping of nitric oxide synthase in the rat brain , 1992, Neuroscience.

[29]  R. Wenthold,et al.  The NMDA receptor subunits NR2A and NR2B show histological and ultrastructural localization patterns similar to those of NR1 , 1994, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[30]  S. Mikawa,et al.  Disruption of AMPA receptor GluR2 clusters following long‐term depression induction in cerebellar Purkinje neurons , 2000, The EMBO journal.

[31]  W. Regehr,et al.  Prolonged Synaptic Currents and Glutamate Spillover at the Parallel Fiber to Stellate Cell Synapse , 2000, The Journal of Neuroscience.

[32]  R. Tsien,et al.  Synergies and Coincidence Requirements between NO, cGMP, and Ca2+ in the Induction of Cerebellar Long-Term Depression , 1997, Neuron.

[33]  M. Santacana,et al.  Neuronal and inducible nitric oxide synthase expression and protein nitration in rat cerebellum after oxygen and glucose deprivation , 2001, Brain Research.

[34]  S. Snyder,et al.  Localization of nitric oxide synthase indicating a neural role for nitric oxide , 1990, Nature.

[35]  N. Berretta,et al.  Tonic facilitation of glutamate release by presynaptic N-methyl-d-aspartate autoreceptors in the entorhinal cortex , 1996, Neuroscience.

[36]  J. Garthwaite,et al.  Long‐Term Depression in Rat Cerebellum Requires both NO Synthase and NO‐sensitive Guanylyl Cyclase , 1996, The European journal of neuroscience.

[37]  R. Tsien,et al.  Long-term depression in cerebellar Purkinje neurons results from coincidence of nitric oxide and depolarization-induced Ca2+ transients , 1995, Neuron.

[38]  D. Linden,et al.  An evaluation of the nitric oxide/cGMP/cGMP-dependent protein kinase cascade in the induction of cerebellar long-term depression in culture , 1995, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[39]  W. Lim,et al.  PSD-95 Assembles a Ternary Complex with theN-Methyl-d-aspartic Acid Receptor and a Bivalent Neuronal NO Synthase PDZ Domain* , 1999, The Journal of Biological Chemistry.

[40]  P. Reiner,et al.  Localization of the cGMP-dependent protein kinases in relation to nitric oxide synthase in the brain , 1999, Journal of Chemical Neuroanatomy.

[41]  D. Linden,et al.  Expression of Cerebellar Long-Term Depression Requires Postsynaptic Clathrin-Mediated Endocytosis , 2000, Neuron.

[42]  M. Ito,et al.  Cerebellar long-term depression: characterization, signal transduction, and functional roles. , 2001, Physiological reviews.

[43]  F. Crépel,et al.  Activation of protein kinase C induces a long-term depression of glutamate sensitivity of cerebellar Purkinje cells. An in vitro study , 1988, Brain Research.

[44]  T. Otis,et al.  Neuronal Glutamate Transporters Control Activation of Postsynaptic Metabotropic Glutamate Receptors and Influence Cerebellar Long-Term Depression , 2001, Neuron.

[45]  M. Ito,et al.  A unique role of protein phosphatases in cerebellar long-term depression. , 1995, Neuroreport.

[46]  WG Regehr,et al.  Contributions of calcium-dependent and calcium-independent mechanisms to presynaptic inhibition at a cerebellar synapse , 1996, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[47]  P. Ascher,et al.  Presynaptic N-methyl-D-aspartate receptors at the parallel fiber-Purkinje cell synapse. , 2000, Proceedings of the National Academy of Sciences of the United States of America.

[48]  Anatol C. Kreitzer,et al.  Retrograde Inhibition of Presynaptic Calcium Influx by Endogenous Cannabinoids at Excitatory Synapses onto Purkinje Cells , 2001, Neuron.

[49]  D. Linden.  The expression of cerebellar LTD in culture is not associated with changes in AMPA-receptor kinetics, agonist affinity, or unitary conductance , 2001, Proceedings of the National Academy of Sciences of the United States of America.