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Electrical synapse formation disrupts calcium‐dependent exocytosis, but not vesicle mobilization
Author(s) -
Neunuebel Joshua P.,
Zoran Mark J.
Publication year - 2005
Publication title -
synapse
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.809
H-Index - 106
eISSN - 1098-2396
pISSN - 0887-4476
DOI - 10.1002/syn.20139
Subject(s) - neurotransmission , synaptic vesicle , neurotransmitter , synapse , neuroscience , chemistry , synaptogenesis , postsynaptic potential , calcium , synaptic vesicle recycling , biophysics , biology , vesicle , biochemistry , receptor , central nervous system , organic chemistry , membrane
Electrical coupling exists prior to the onset of chemical connectivity at many developing and regenerating synapses. At cholinergic synapses in vitro, trophic factors facilitated the formation of electrical synapses and interfered with functional neurotransmitter release in response to photolytic elevations of intracellular calcium. In contrast, neurons lacking trophic factor induction and electrical coupling possessed flash‐evoked transmitter release. Changes in cytosolic calcium and postsynaptic responsiveness to acetylcholine were not affected by electrical coupling. These data indicate that transient electrical synapse formation delayed chemical synaptic transmission by imposing a functional block between the accumulation of presynaptic calcium and synchronized, vesicular release. Despite the inability to release neurotransmitter, neurons that had possessed strong electrical coupling recruited secretory vesicles to sites of synaptic contact. These results suggest that the mechanism by which neurotransmission is disrupted during electrical synapse formation is downstream of both calcium influx and synaptic vesicle mobilization. Therefore, electrical synaptogenesis may inhibit synaptic vesicles from acquiring a readily releasable state. We hypothesize that gap junctions might negatively interact with exocytotic processes, thereby diminishing chemical neurotransmission. Synapse 56:154–165, 2005. © 2005 Wiley‐Liss, Inc.