en
Scientific article
English

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

Published inPflügers Archiv, vol. 432, no. 5, p. 853-858
Publication date1996-09
Abstract

Treatment with 100 or 250 μM 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 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.

eng
Keywords
  • Acetylcholine / metabolism
  • Animals
  • Calcimycin / pharmacology
  • Calcium / metabolism
  • Cholinergic Fibers / drug effects
  • Cholinergic Fibers / metabolism
  • Electric Organ / drug effects
  • Electric Organ / physiology
  • Female
  • Male
  • Potassium Chloride
  • Proteolipids / metabolism
  • Synaptic Transmission / drug effects
  • Synaptosomes / drug effects
  • Synaptosomes / metabolism
  • Torpedo
  • Zinc / pharmacology
  • Torpedo electric organ
  • Mediatophore
Citation (ISO format)
DUNANT, Yves et al. Activation and desensitisation of acetylcholine release by zinc at <i>Torpedo</i> nerve terminals. In: Pflügers Archiv, 1996, vol. 432, n° 5, p. 853–858. doi: 10.1007/s004240050208
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Article (Published version)
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ISSN of the journal0031-6768
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