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2003 Fiscal Year Final Research Report Summary

Epileptic Discharges and the neural network in the hippocampus.

Research Project

Project/Area Number 14570050
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field General physiology
Research InstitutionKURUME UNIVERSITY

Principal Investigator

HIGASHI Hideho  Kurume Univ Sch of Med, Dept of Physiol, Professor, 医学部, 教授 (10098907)

Project Period (FY) 2002 – 2003
Keywordsneural network / hippocampus / epilepsy / lidocaine / A_1 receptor / adenosine / EPSP / IPSP
Research Abstract

Extracellular recordings were made from CA1 and CA3 regions in the rat hippocampal tissue slices. Administration of various concentration (1-100μM) of lidocaine induced a transient inhibition, which was followed by an augmentation of the maximal slope of field postsynaptic potentials (fPSPs) and field excitatory postsynaptic potentials (fEPSPs). The amplitude of presynaptic volleys was simply depressed by lidocaine in a conaentration-dependent manner. Administration of adenosine 1 (A_1) receptor antagonist, DPCPX (1μM),diminished the transient inhibition of the fPSPs and fEPSPs. Intracellular recordings from CA1 neurons revealed that lidocaine suppressed the amplitude of both the evoked fast EPSPs and fast IPSP in a concentration-pendent manner, and the IC_<50> values for fast EPSPs and fast IPSP were 68μM and 7μM, respectively. Studies on evoked PSPs showed that lidocaine at low concentration (<30μM) reduced the amplitude of the fast and late IPSPs, but augmented that of the fast EPSPs. Administration of lidocaine (1-30μM) induced a DPCPX-sensitive transient hyperpolarization. In CA3 neurons, adenosine (500μM) induced a DPCPX-sensitive hyperpolarization, which was blocked by lidocaine. When the slice was incised in the stratum oriens in CA2 region, lidocaine (100μM) only augmented the fEPSPs. These results suggest that the transient inhibition of the fPSPs and fEPSPs is mainly mediated by the hyperpolarization of CA3 neurons via A_1 receptor activation. The augmentation of the fPSPs may result from the relative resistance of the fast EPSPs for the lidocaine-induced inhibition, in comparison with the fast IPSP. Thus, the intrinsic circuit of CA3 region and the synaptic inputs from CA2 and CA3 region may contribute to the transient inhibition and subsequent augmentation of the fPSPs and fEPSPs.

  • Research Products

    (16 results)

All Other

All Publications (16 results)

  • [Publications] Yasumoto S: "Direct and indirect actions of dopamine on the membrane potential in medium spiny neurons of the mouse neostriatum."J.Neurophysiol.. 87. 1234-1243 (2002)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Niiyama S: "Bupivacaine, but not tetracaine, protects against the in vitro ischemic insult of rat hippocampal CA1 neurons."Neurosci.Res.. 42. 231-241 (2002)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Tanaka E: "Extrusion of intracellular calcium ion after in vitro ischemia in the rat hippocampal CA1 region."J.Neurophysiol.. 88. 879-887 (2002)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Tanaka E: "The presynaptic modulation glutamate release and the membrane dysfunction induced by in vitro ischemia in rat hippocampal CA1 neurons."Life Sci.. 72. 363-374 (2002)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Wang D-S: "Postnatal changes in the overall postsynaptic currents evoked in CA1 pyramidal neurons of the rat hippocampus."Life Sci.. 72. 341-353 (2002)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Hattori G: "Electrical and pharmacological properties of the slow depolarization induced by Schaffer collateral stimulation in asfrocytes of the rat hippocampal CA1 region."Neurosci.Lett.. 343. 85-88 (2003)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Tanaka E: "Arachidonic acid metabolite contribute to the irreversible depolarization induced by in vitro ischemia."J.Neurophysiol.. 90. 3213-3223 (2003)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Tanaka E: "A new cytochemical method for ultrastructural localization of Co~<2+> in rat hippocampal CA1 pyramidal neurons in vitro."J.Neurosci.Methods. 135. 1-8 (2003)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Yasumoto S: "Direct and indirect actions of dopamine on the membrane potential in medium spiny neurons of the mouse neostriatum."J.Neurophysiol.. 87. 1234-1243 (2002)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Niiyama S: "Bupivacaine, but not tetracaine, protects against the in vitro ischemic insult of rat hippocampal CA1 neurons."Neurosci. Res.. 42. 231-241 (2002)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Tanaka E: "Extrusion of intracellular calcium ion after in vitro ischemia in the rat hippocampal CA1 region."J.Neurophysiol.. 88. 879-887 (2002)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Tanaka E: "The presynaptic modulation of glutamate release and the membrane dysfunction induced by in vitro ischemia in rat hippocampal CA 1 neurons."Life Sci.. 72. 363-374 (2002)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Wang D-S: "Postnatal changes in the overall postsynaptic currents evoked in CA1 pyramidal neurons of the rat hippocampus."Life Sci.. 72. 341-353 (2002)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Hattori G: "Electrical and pharmacological properties of the slow depolarization induced by Schaffer collateral stimulation in astrocytes of the rat hippocampal CA1 region."Neurosci.Lett.. 343. 85-88 (2003)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Tanaka E: "Arachidonic acid metabolites contribute to the irreversible depolarization induced by in vitro ischemia."J.Neurophysiol.. 90. 3213-3223 (2003)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Tanaka E: "A new cytochemical method for ultrastructural localization of Co^<2+> in rat hippocampal CA1 pyramidal neurons in vitro."J.Neurosci.Methods. 135. 1-8 (2004)

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 2005-04-19  

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