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Activity‐induced large amplitude postsynaptic mPSPs at soma–soma synapses between Lymnaea neurons
Author(s) -
Dunn T.W.,
McCamphill P.K.,
Syed N.I.
Publication year - 2009
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.20589
Subject(s) - soma , postsynaptic potential , neuroscience , chemistry , lymnaea , biology , snail , ecology , receptor , biochemistry
Abstract Spontaneous transmitter release has been observed at various synapses that permit analysis at a sufficient resolution as a miniature postsynaptic potential (mPSP). However, the precise mechanisms that regulate spontaneous transmitter release have not yet been fully defined. Activity and ligand‐mediated modulation of large amplitude, spontaneous events significantly enhances postsynaptic excitation in the absence of action potential activity suggesting a more complicated role for this mode of transmitter release, and thus warrants further analysis. Here, we used Lymnaea soma–soma synaptic connections to demonstrate that a transient increase in both the frequency and amplitude of spontaneous events (mPSPs) occurs following a short burst of action potentials in the presynaptic cell. These events were of presynaptic origin and the increase in mPSP amplitude could also be achieved with a stimulatory concentration of ryanodine. Ryanodine also occluded the activity‐induced increase in mPSP amplitude implicating calcium release from these channels in the production of large amplitude spontaneous transmitter release events. This suggests that presynaptic activity triggers ryanodine receptor‐mediated large amplitude minis, indicating that although these events are action potential‐independent, they are nevertheless responsive to the prior activity of the synapse. Synapse 63:117–125, 2009. ©2008 Wiley‐Liss, Inc.