脳スライス標本における最後野ニューロンのATP受容体を介する興奮性の修飾 Purinergic modulation of area postrema neuronal excitability in rat brain slices.

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Author(s)

    • 兒玉 直紀 Kodama Naoki
    • 岡山大院・医歯総合・咬合口腔機能再建学分野 Dept. Occl. Oral. Func. Rehab.,Okayama Univ. Graduate Sch. Med. & Dent., Okayama, Japan
    • 舩橋 誠 Funahashi Makoto
    • 岡山大院・医歯総合・口腔生理 Dept. Oral Physiol., Okayama Univ. Graduate Sch. Med. & Dent., Okayama, Japan
    • 皆木 省吾 Minagi Shogo
    • 岡山大院・医歯総合・咬合口腔機能再建学分野 Dept. Occl. Oral. Func. Rehab.,Okayama Univ. Graduate Sch. Med. & Dent., Okayama, Japan
    • 松尾 龍二 Matsuo Ryuji
    • 岡山大院・医歯総合・口腔生理 Dept. Oral Physiol., Okayama Univ. Graduate Sch. Med. & Dent., Okayama, Japan

Abstract

Histochemical and electrophysiological studies have reported the presence of P2X purinoceptors in the area postrema (AP). In this study, we sought to clarify the purinergic modulation of AP neuronal excitability using a patch-clamp technique in rat brain slices. Voltage-clamp recordings were obtained from 40 neurons in the presence of TTX (1 μM) at a holding potential of –50 mV. Each cell was tested whether it displays the hyperpolarization-activated cation current (I<SUB>h</SUB>) or not. Twenty of 40 cells tested showed excitatory responses to ATP (up to 1 mM), including cells displaying 1) ATP-induced inward currents with significant changes in the frequency of miniature EPSCs (mEPSCs) (n=14, including 1 cell displaying I<SUB>h</SUB> and 13 cells not displaying I<SUB>h</SUB>), 2) ATP-induced inward currents without significant changes in the frequency of mEPSCs (n=1, cells not displaying I<SUB>h</SUB>), and 3) marked increases in the frequency of mEPSCs without any direct postsynaptic currents (n=5, including 4 cells displaying I<SUB>h</SUB> and 1 cell not displaying I<SUB>h</SUB>). PPADS (10-20 μM), selective P2X purinoceptor antagonist, abolished the responses of AP neurons to the bath application of ATP in all cells tested (n=10). These results indicate that P2X purinoceptors are present both pre- and post- and/or extrasynaptically in the AP. Further this study suggests the different localization of purinoceptors between pacemaker cells displaying I<SUB>h</SUB> and cells not displaying I<SUB>h</SUB>. <b>[Jpn J Physiol 55 Suppl:S188 (2005)]</b>

Histochemical and electrophysiological studies have reported the presence of P2X purinoceptors in the area postrema (AP). In this study, we sought to clarify the purinergic modulation of AP neuronal excitability using a patch-clamp technique in rat brain slices. Voltage-clamp recordings were obtained from 40 neurons in the presence of TTX (1 μM) at a holding potential of –50 mV. Each cell was tested whether it displays the hyperpolarization-activated cation current (I<SUB>h</SUB>) or not. Twenty of 40 cells tested showed excitatory responses to ATP (up to 1 mM), including cells displaying 1) ATP-induced inward currents with significant changes in the frequency of miniature EPSCs (mEPSCs) (n=14, including 1 cell displaying I<SUB>h</SUB> and 13 cells not displaying I<SUB>h</SUB>), 2) ATP-induced inward currents without significant changes in the frequency of mEPSCs (n=1, cells not displaying I<SUB>h</SUB>), and 3) marked increases in the frequency of mEPSCs without any direct postsynaptic currents (n=5, including 4 cells displaying I<SUB>h</SUB> and 1 cell not displaying I<SUB>h</SUB>). PPADS (10-20 μM), selective P2X purinoceptor antagonist, abolished the responses of AP neurons to the bath application of ATP in all cells tested (n=10). These results indicate that P2X purinoceptors are present both pre- and post- and/or extrasynaptically in the AP. Further this study suggests the different localization of purinoceptors between pacemaker cells displaying I<SUB>h</SUB> and cells not displaying I<SUB>h</SUB>. <b>[Jpn J Physiol 55 Suppl:S188 (2005)]</b>

Journal

  • Proceedings of Annual Meeting of the Physiological Society of Japan

    Proceedings of Annual Meeting of the Physiological Society of Japan 2005(0), S188-S188, 2005

    PHYSIOLOGICAL SOCIETY OF JAPAN

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