Possible association of alcohol tolerance with increased synaptic Ca 2+ sensitivity

Marina A. Lynch, John M. Littleton

Research output: Contribution to journalArticlepeer-review

81 Scopus citations


The inhibitory effect of ethanol on neurotransmitter release1,2 has been suggested to be due to either reduced Ca2+ entry3 or increased removal of free intracellular Ca2+ from the synapse4. The use of the Ca2+ ionophore, A23187, to allow direct access of external Ca2+ to the presynaptic interior 5 should help to determine which of these two factors is the more important, as ethanol should inhibit A23187-induced release of transmitter only if increased Ca2+ removal from the synapse is important. Here we show in rat striatal slices that, although 3H-dopamine release evoked by depolarization with 40 mM K+ is inhibited by 50 mM ethanol, the release evoked by A23187 is enhanced by the presence of ethanol in vitro. The results suggest that ethanol reduces depolarization-induced transmitter release by reducing Ca2+ entry to the presynaptic terminal. However, for brain slices taken from rats made tolerant to ethanol, 3H-dopamine release in the absence of ethanol showed altered characteristics; both K + depolarization and A23187 released a significantly greater fraction of 3H-dopamine from these slices than from controls. Thus tolerance to the inhibitory effect of ethanol on release may develop by a mechanism involving increased sensitivity of the terminal to Ca2+ entry.

Original languageEnglish
Pages (from-to)175-176
Number of pages2
Issue number5913
StatePublished - 1983

ASJC Scopus subject areas

  • General


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