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1995 Fiscal Year Final Research Report Summary

Regulation of exocytotic release of neurotransmitters by Ca^<2+> and associated proteins.

Research Project

Project/Area Number 06454146
Research Category

Grant-in-Aid for General Scientific Research (B)

Allocation TypeSingle-year Grants
Research Field General physiology
Research InstitutionTohoku University (1995)
Kyoto University (1994)

Principal Investigator

YAWO Hiromu  Tohoku University, School of Medicine, Professor, 医学部, 教授 (00144353)

Project Period (FY) 1994 – 1995
Keywordssynapse / presynaptic / exocytosis / calcium / adrenergic / noradrenaline / neuromodulator / ciliary ganglion
Research Abstract

The giant presynaptic terminal of chick ciliary ganglion was used to examine how noradrenaline (NA) modulates neurotransmitter release. The cholinergic excitatory synaptic currents (EPSCs) were recorded under whole-cell voltage clamp of the postsynaptic neuron. Although the EPSC was potentiated by NA,the current directly activated by acetylcholine (I_<ACh>) was unaffected. NA also increased the quantal contents without changing the quantal size. The NA-dependent potentiation was antagonized by neither phentolamine nor propranolol. The EPSC was also potentiated by adrenaline and dopamine but not by normetanephrine, phenylephrine or isoproterenol. The EPSC was attenuated by clonidine. Therefore, NA potentiated the transmitter release through a receptor pharmacologically different from both alpha- or beta- adrenergic receptors. The Ca^<2+> increment produced by an action potential (DELTA[Ca^<2+>]_<pre>) was reduced by NA through an alpha_2-adrenergic receptor. However, when alpha_<2+>-adrenergic receptors were blocked, neither DELTA[Ca^<2+>]_<pre> nor resting Ca^<2+> were changed by NA.The [Ca^<2+>]_o-EPSC relation was shifted by NA, decreasing the half saturating [Ca^<2+>]_o, without changing the maximum. It is concluded that NA-dependent potentiation of transmitter release was due to an increase in the Ca^<2+> sensitivity of the exocytotic process. The enhancement of the fusion probability is suggested.

  • Research Products

    (8 results)

All Other

All Publications (8 results)

  • [Publications] Yawo, H. et al.: "Modulation of presynaptic calcium channels by neurotransmitters." Biocned. Res.15. 9-16 (1994)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Endo, K. and Yawo,H.: "Cellulan mechanisms of enkephalin action on transmitter release from the giant presynaptic terminal of chick ciliary ganglion." Jpn. J. Physiol.44. S177- (1994)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Yawo, H. and Endo, K.: "Facilitation of Transmitter ralease by noradrenaline from the giant presyraptic terminal of chick ciliary garglion." Neurosci. Res. Suppl.19. S30- (1994)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Yawo, H.: "Noradrenaline modulates transmitter release by enhancing the Ca^<2+> sensitivity of exocytosis in the chick ciliary Guglion" J. Physiol. Lond.(印刷中). (1996)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Yawo, H.et al.: "Modulation of presynaptic calcium channels by neurotransmitters." Biomed.Res.15, suppl. 1. 9-16 (1994)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Endo, K.and Yawo, H.: "Cellular mechanisms of enkephalin action on transmitter release from the giant presynaptic terminal of the chick ciliary ganglion." Jpn J.Physiol.44, suppl. 1. S177 (1994)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Yawo, H.and Endo, K.: "Facilitation of transmitter release by noradrenaline from the giant presynaptic terminal of chick ciliary ganglion." Neurosci. Res.Suppl. 19. S30 (1994)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Yawo, H.: "Noradrenaline modulates transmitter release by enhancing the Ca2+sensitivity of exocytosis in the chick ciliary presynaptic terminal." J.Physiol. Lond.(in press).

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

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Published: 1997-03-04  

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