The decrease in the presynaptic calcium current is a major cause of short-term depression at a calyx-type synapse

Jianhua Xu, Ling Gang Wu

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Repetitive nerve firings cause short-term depression (STD) of release at many synapses. Its underlying mechanism is largely attributed to depletion of a readily releasable vesicle pool (RRP) and a decreased probability of releasing a readily releasable vesicle during an action potential. Which of these two mechanisms is dominant and the mechanism that decreases the release probability remain debated. Here, we report that a decreased release probability is caused by a calcium-induced inhibition of presynaptic calcium channels, particularly P/Q-type channels at the calyx of Held in rat brainstem. This mechanism was the dominant cause of STD in a wide range of stimulation conditions, such as during 2 to 20 action potential-equivalent stimuli (AP-e) at 0.2-30 Hz and after 2 to 20 AP-e at 0.2-100 Hz. Only during ≥100 Hz AP-e was depletion the dominant mechanism.

Original languageEnglish (US)
Pages (from-to)633-645
Number of pages13
Issue number4
StatePublished - May 19 2005


ASJC Scopus subject areas

  • Neuroscience(all)

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