Distribution patterns of pyramidal and thalamocortical inputs to the parvalbumin-expressing GABAergic neurons in rat frontal cortex

Abstracts mice, GluN2B was mainly expressed in principal neurons, whereas GluN2D was selective to GAD-positive interneurons. The distinct cellular expression was already found at postnatal day 5, when barrels are formed. GluN2B-positive puncta were predominant and most of them were negative to GluN2D, whereas GluN2D-positive puncta were few in number and occasionally possessed GluN2B. By immunoelectron microscopy, asymmetrical synapses on spiny neurons preferentially expressed GluN2B, whereas those on parvalbumin-positive interneurons did GluN2D. Thus, the two subunits are largely utilized in distinct neuronal populations in the somatosensory cortex from early postnatal development. This will explain, at least partly, the failed refinement of synaptic circuits made by excitatory neurons in GluN2Bdeficient, but not GluN2D-deficient, mice. doi:10.1016/j.neures.2009.09.700

P2-a39 Reversible changes in complex hippocampal synapses of CA3 thorny excrescences during hibernation of Siberian ground squirrel: a serial ultrathin section investigation in vivo Ilya Patrushev Institute of Cell Biophysics RAS, Pushchino, Russia Hibernation as a natural model for studying synaptic plasticity (Popov et al., 2007) allows obtaining functional states with alternative synaptic transmission efficacy. It is shown that multiple presynaptic varicosities of different mossy fibers can be located at individual thorny excrescences of CA3 pyramidal neurons. In hibernation more than half of thorns are retracted, with volumes and surface areas of thorny excrescences, areas of synaptic active zones and a percentage of the surface occupied by active zones considerably decreased. In 2–3 hours after the provoked arousal most of these values are restored except the percentage of spine surface occupied by active zones of synapse, which remains the same. Based on the results obtained it is concluded that in hibernation synaptic active zones are partly resembled and receptor proteins are dispended in membrane of thorny excrescence, then during arousal there is a reverse process of grouping and clusterization of receptor proteins, that leads to increase in the surface area of active zones. doi:10.1016/j.neures.2009.09.701

P2-b01 Inflammation triggers noxious synaptic alteration in the rat spinal dorsal horn in vivo Hidemasa Furue 1,2 , Keiji Imoto 1 , Megumu Yoshimura 2 1

National Institite for Physiological Sciences, Japan; 2 Department of Integrative Physiology, Grad. Sch. Med. Sci., Kyushu University, Japan In vivo patch-clamp recordings were made from substantia gelatinosa (SG, lamina II) of the spinal cord in naïve and inflamed rats to investigate plastic changes in the noxious synaptic transmission following inflammation. After thoracolumbar laminectomy was performed and the dorsal surface of the lumbar spinal cord was exposed, patch electrodes were inserted in the SG. Whole-cell recordings were made from SG neurons. SG neurons tested exhibited spontaneous EPSCs. Cutaneous pinch stimulation elicited a barrage of EPSCs. The amplitude and frequency of spontaneous and pinch-evoked EPSCs were higher in inflamed than naïve rats. The voltage dependence of pinch-elicited EPSCs and the sensitivity of AMPA receptor antagonists suggest that pinch-evoked EPSCs in inflamed but not naïve rats are mediated through calcium-permeable AMPA receptors. These plastic changes may have a crucial role in the induction of central sensitization following inflammation. doi:10.1016/j.neures.2009.09.702

P2-b02 Distribution patterns of pyramidal and thalamocortical inputs to the parvalbumin-expressing GABAergic neurons in rat frontal cortex Naoki Shigematsu, Yoshiyuki Kubota, Yasuo Kawaguchi Div. Cerebral Circuitry, NIPS, Okazaki, Japan Neocortical parvalbumin-expressing neurons (PV neurons) generate the fast rhythms by interaction with the excitatory inputs. PV neurons receive excitations from two major sources, pyramidal and thalamocortical (TC) cells. To reveal the differences of two inputs in excitation to PV neurons, their terminal distributions onto PV neurons were compared in rat frontal cortex. Pyramidal terminals were visualized by immunolabeling of vesicular glutamate transporter type 1 (VGluT1), and TC ones by that of type 2 (VGluT2). PV neurons were visualized by immunolabeling, or Lucifer yellow injection into vicia villosa agglutinin-labeled cells. Their appositions were identified by confocal images. PV dendrites and somata had much more appositions to the terminal boutons positive for VGluT1 than to those for VGluT2 in individual layers. VGluT2 appositions to the somata were found mostly in layer 4, but those to the dendrites were not. These results suggest that the

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direct TC interaction with the frontal PV population occurs at their somata of layer 4. doi:10.1016/j.neures.2009.09.703

P2-b03 Quantitative analysis of excitatory inputs to the three groups of the neostriatal projection neurons in rats Takahiro Sonomura 1 , Takahiro Furuta 2 , Keiko Okamoto-Furuta 3 , Tomo Unzai 2 , Masanori Uemura 1 , Takeshi Kaneko 2,4 1

Department Anat. Oral. Sci., Kagoshima University, Kagoshima, Japan; Department Morphological Brain Sci., Grad. Sch. Med., Kyoto University, Kyoto, Japan; 3 Electron Microscopy Center, Grad. Sch. Med., Kyoto University, Kyoto, Japan; 4 CREST, JST, Japan 2

The majority of neostriatal neurons are medium-sized projection neurons with spiny dendrites and have so far been classified into three groups: striatoentopeduncular/striatonigral neurons producing PPD, and striatopallidal neurons producing PPE, and striatoinnominatal neurons producing PPTB. These projection neurons resceive excitatory inputs from the neocortex and the thalamus. In this study, we quantitatively analysed the relation between the three groups of the projection neurons and two kinds of inputs in the neostriatum. The appositions of the dendrites to the inputs were observed three-dimensionally with a confocal laser-scanning microscope. Some appositions were examined electron-microscopically and calculated the densities of inputs. The striatoinnominatal neurons recived glutamatergic excitatory afferents less than the striatonigral neurons or striatopallidal neurons. doi:10.1016/j.neures.2009.09.704

P2-b04 Analysis of the synaptic vesicle transportation of Syntaxin1A (R151G) knock-in mouse Yumi Watanabe 1 , Yukiyo Tada 2 , Ayako Banba 2 , Kenji Sakimura 3 , Michihiro Igarashi 1,2 1

Transdisc Res. Prog., Niigata University, Japan; 2 Div. of Mol. Cell. Biol., Grad. Sch. of Med. Dent. Sci., Niigata University, Japan; 3 Department of Cell Neurobiol, Brain. Res. Inst., Niigata University, Japan

We previously found that the autophosphorylated CaMKII interacts with syntaxin1A, a t-SNARE operating the vesicle docking and fusion, in the presence of submicromolar Ca2+ , and demonstrated at the cellular level that this binding modulates the frequency of exocytosis. This interaction is strongly dependent upon R151 of syntaxin-1A, a highly conserved residue localized in the linker domain of syntaxin1A, and R151G syntaxin-1A completely lost the activities both binding to CaMKII in vitro. To understand the significance of this interaction more in detail, we made the knock-in mice having R151G syntaxin-1A from the C57/BL6-dervied ES cells. Although the homozygous mice with this mutation are developing without large defect, in the comprehensive behavioral test batteryt, the mutant showed increase in motility and decrease in anxiety-like behavior. Currently we are working on further characterization of the synaptic vesicle transportation of this mutant. doi:10.1016/j.neures.2009.09.705

P2-b05 Effects of TRPA1 and TRPV1 agonists on synaptic transmission in morphologically distinct cell types in substantia gelatinosa of the rat spinal cord Daisuke Uta 1,2 , Hidemasa Furue 1,2 , Keiji Imoto 1 , Megumu Yoshimura 2 1

National Institute for Physiological Sciences, Japan; grative Physiology, Kyushu University, Japan

2

Department of Inte-

Whole-cell patch-clamp recordings were made from substantia gelatinosa neurons of spinal cord slices to examine effects of TRP receptor agonists on the excitatory and inhibitory synaptic transmission. CA increased the frequency and amplitude of spontaneous EPSCs. The excitatory effect of CA on spontaneous EPSCs was observed in about 30 % of total neurons tested. In morphological analysis, SG neurons sensitive to CA were identified as the vertical neurons. CAP also increased the frequency of spontaneous EPSCs in most SG neurons. In all SG neurons sensitive to CA, CAP also increased the frequency of sEPSCs. However, CA and CAP had no effects on the frequency and amplitude of GABAergic and glycinergic spontaneous IPSCs. The present results suggest that activation of TRP receptors in the presynaptic terminals of afferent fibers facilitates excitatory synaptic transmission in the SG, though TRPA1 activation selectively enhances the synaptic inputs to excitatory interneurons. doi:10.1016/j.neures.2009.09.706