Activation and desensitisation of aetylcholine release by zinc at Torpedo nerve terminals

Yves Dunant, Françoise Loctin, Jean Paul Vallée, Arpad Parducz, Bernard Lesbats, Maurice Israël

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Treatment with 100 or 250μM ZnCl2 irreversibly blocked neurotransmission in the Torpedo electric organ by inhibiting acetylcholine (ACh) release. In Zn2+-treated tissue, release failure did not result from impairment of Ca2+ entry since stimulation still provoked an accumulation of Ca2+. Also pretreatment of isolated synaptosomes with Zn2+ inhibited to the same extent the release elicited by KCl evoked depolarisation and the release elicited by using the Ca2+ ionophore A23187. On the other hand, after application of A23187, Zn2+ by itself efficiently triggered ACh release elicited by KCl-evoked depolarisation and the release elicited by using the Ca2+ ionophore A23187. On the other hand, after application of A23187, Zn2+ by itself efficiently triggered ACh release from synaptosomes. This dual effect of Zn2+ was also observed to occur in proteoliposomes equipped with mediatophore (a protein of the presynaptic membrane characterised by its capability to support Ca2+-dependent transmitter release). Hence, Zn2+ mimicked two fundamental actions of Ca2+ on nerve terminals, which are: (1) the immediate activation of release, and (2) a more slowly developing desensitisation of release. Zn2+ was more powerful than Ca2+ for both actions. It is concluded that the dual action of Zn2+ on the mediatophore protein accounts at least in part for its complex effects on neurotransmission.

Original languageEnglish
Pages (from-to)853-858
Number of pages6
JournalPflugers Archiv European Journal of Physiology
Volume432
Issue number5
DOIs
Publication statusPublished - 1996

Keywords

  • Acetylcholine release
  • Calcium
  • Mediatophore
  • Synaptic transmission
  • Synaptosomes
  • Torpedo electric organ
  • Zinc

ASJC Scopus subject areas

  • Physiology
  • Clinical Biochemistry
  • Physiology (medical)

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