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Adaptive and non‐adaptive changes in activity‐deprived presynaptic terminals
Author(s) -
Horellou Süzel,
Pascual Olivier,
Triller Antoine,
Marty Serge
Publication year - 2014
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/ejn.12399
Subject(s) - vesicle , synaptic vesicle , excitatory postsynaptic potential , biophysics , hippocampal formation , tetrodotoxin , postsynaptic potential , neuroscience , chemistry , biology , microbiology and biotechnology , biochemistry , receptor , inhibitory postsynaptic potential , membrane
How the number of docked vesicles is regulated is still unclear. Following chronic activity blockade the number of docked vesicles increases, providing a model through which to address this issue. We tested the hypotheses that the number of docked vesicles is regulated with the size of the terminal, and by the level of Rab3‐interacting molecule 1/2 ( RIM 1/2). We immobilized mouse hippocampal slice cultures by high‐pressure freezing after 3 days of tetrodotoxin treatment and analysed them by electron microscopy. The number of docked vesicles, the size of the active zones and the amount of G lu A 2 were increased after activity blockade. However, there was no modification of either the total number of synaptic vesicles or the area of presynaptic profiles. Surprisingly, immunocytochemistry showed no change in the mean level of RIM 1/2 per terminal but its distribution was modified. Additionally, there was no modification of the mean frequency or amplitude of miniature excitatory postsynaptic currents, but the distribution of amplitudes was modified. These results indicate a specific homeostatic regulation of the synaptic junction. The number of docked vesicles does not seem to be regulated by the amount of RIM 1/2. The modification of the distribution, but not the amount, of RIM 1/2 may explain the contradiction between the morphological and electrophysiological findings.