Presynaptic activation of silent synapses and growth of new synapses contribute to intermediate and long-term facilitation in Aplysia

Joung Hun Kim, Hiroshi Udo, Hsiu Ling Li, Trisha Y. Youn, Mary Chen, Eric R. Kandel, Craig H. Bailey

Research output: Contribution to journalArticle

108 Citations (Scopus)

Abstract

The time course and functional significance of the structural changes associated with long-term facilitation of Aplysia sensory to motor neuron synaptic connections in culture were examined by time-lapse confocal imaging of individual sensory neuron varicosities labeled with three different fluorescent markers: the whole-cell marker Alexa-594 and two presynaptic marker proteins - synaptophysin-eGFP to monitor changes in synaptic vesicle distribution and synapto-PHluorin to monitor active transmitter release sites. Repeated pulses of serotonin induce two temporally, morphologically, and molecularly distinct presynaptic changes: (1) a rapid activation of silent presynaptic terminals by filling of preexisting empty varicosities with synaptic vesicles, which parallels intermediate-term facilitation, is completed within 3-6 hr and requires translation but not transcription and (2) a slower generation of new functional varicosities which occurs between 12-18 hr and requires transcription and translation. Enrichment of empty varicosities with synaptophysin accounts for 32% of the newly activated synapses at 24 hr, whereas newly formed varicosities account for 68%.

Original languageEnglish
Pages (from-to)151-165
Number of pages15
JournalNeuron
Volume40
Issue number1
DOIs
Publication statusPublished - Sep 25 2003

All Science Journal Classification (ASJC) codes

  • Neuroscience(all)

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