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1998 Fiscal Year Final Research Report Summary

Phaimacological analysis of a novel NMDA receptor mediating synaptic responses involued in pain transmossion in the spinal cord

Research Project

Project/Area Number 09680815
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field 神経・脳内生理学
Research InstitutionSaga Medical School

Principal Investigator

KUMAMOTO Eiichi  Saga Medical School, Associate Professor, 医学部, 助教授 (60136603)

Co-Investigator(Kenkyū-buntansha) YOSHIMURA Megumu  Saga Medical School, Full Professor, 医学部, 教授 (10140641)
Project Period (FY) 1997 – 1998
KeywordsSpinal cord / Substantia gelatinosa / Pain / glutamate / Patch-clamp / Synaptic transmission
Research Abstract

It is thought that peripheral noxious information is transmitted through unmyclinated C-and thinly-myelinated Adelta-afferents to superficial dorsal horn, particularly substantia gelatinosa (SG, lamina II of Rexed) neurons, in the spinal cord, where the pain transmission is modulated. We examined what effects acutely or chronically pain-eliciting stimuli have on glutamatergic excitatory synaptic transmission by applying the blind whole-cell patch-clamp technique to SG neurons of an adult rat spinal cord slice to which the dorsal root is attached. The SG neurons exhibited not only a non-NMDA but also NMDA response by stimulating repetitively Adelta-afferents ; the latter of which is less sensitive to AP-5 or Mg^2^+ than reported in other central neurons (1). Capsaicin potentiated spontaneous transmitter release (2) while attenuating the amplitude of excitatory postsynaptic currents evoked in SG neurons by stimulating C-, but not Adelta-afferent fibers, for more than 30 min. SG neurons in rats inflamed by an intraplantar injection of complete Freund's adjuvant displayed synaptic transmissions different from those in naive rats. In inflamed rats, SG neurons receiving Abeta-afferent inputs decreased in number whereas those having A43-afferent inputs increased (3). These results demonstrate that glutamatergic transmissions in SG neurons are mediated by both non-NMDA and NMDA receptors and that these exhibit a plastic alteration following a pain stimulation. For example, capsaicin acts on specifically C-fibers, resulting in an inhibition of evoked transmission ; this would account for, at least in part, an analgesic action of capsaicin. Peripheral inflammation induces a reorganization of Abeta-afferents to the SG from deeper laminae ; this may partly contribute to the development of allodynia.

  • Research Products

    (9 results)

All Other

All Publications (9 results)

  • [Publications] Y.Yajiri: "A novel slow excitatory postsynaptic curcent in substantia gelatinosa neurons of the rat spinal coid in vitro" Neuroscience. 76. 673-688 (1997)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] E.Kumamoto: "The pharmacology of amino-acid responses in septal neurons" Progress in Neurobiology. 52. 197-259 (1997)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] E.Kumamoto: "Action of furosemide on GABA and glycine currents in rat septal cholinergic neurons in culture" Brain Research. 776. 246-249 (1997)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Y.Murata: "Phenotypic characterization of septal neurons in culture:immunohistochemistry of GABA,calbindin D-28k and choline acctyltransgerose,and histochemistry of acetglcholinaits." Developmental Brain Research. 105. 1-8 (1998)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] K.Yang: "Capsaicin facilitate excitatory but not inhibitory synaptic transmission in substantia gelatinosa of the rat sprnal cord" Neuroscience Letters. 255. 135-138 (1998)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] T.Nakatsuka: "Plastic changes in sensory inputs to rat substantia gelatinoa neurons following peicpheral inglammation" Pain. (印刷中).

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Y.yajiri, M.Yoshimura, M.Okamoto, H.Takahashi & H.Higashi: "A novel slow excitatory postsynaptic current in substantia gelatinosa neurons of the rat spinal cord in vitro." Neurosciece. 76. 673-688 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] K.yang, E.Kumamoto, H.Furue & M.Yoshimura: "Capsaicin facilitates excitatory but not inhibitory synaptic transmission in substantia gelatinosa of the rat spinal cord." Neurosci.Lett.255. 135-138 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] N.Nakatsuka, J.-S.Park, E.Kumamoto, T.Tamaki & M.Yoshimura: "Plastic Changes in sensory inputs to rat substantia gelationosa neurons following peripheral inflammation" Pain. (in press).

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

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Published: 1999-12-08  

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