title: Adaptive and non-adaptive changes in activity-deprived presynaptic terminals.
abstract: 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 (RIM1/2). 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 GluA2 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 RIM1/2 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 RIM1/2. The modification of the distribution, but not the amount, of RIM1/2 may explain the contradiction between the morphological and electrophysiological findings.
authors.affiliation: Institute of Biology of the Ecole Normale Supérieure, 46 rue d'Ulm, 75005, Paris, France; INSERM U1024, Paris, France; CNRS UMR8197, Paris, France.
authors.forename: Süzel
authors.initials: S
authors.lastname: Horellou
authors.forename: Olivier
authors.initials: O
authors.lastname: Pascual
authors.forename: Antoine
authors.initials: A
authors.lastname: Triller
authors.forename: Serge
authors.initials: S
authors.lastname: Marty
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D019706:Excitatory Postsynaptic Potentials; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism / Q000502:physiology; D051379:Mice; D055369:Miniature Postsynaptic Potentials; D017729:Presynaptic Terminals / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D021381:Protein Transport; D018091:Receptors, AMPA / Q000378:metabolism; D026941:Sodium Channel Blockers / Q000494:pharmacology; D013572:Synaptic Vesicles / Q000378:metabolism*; D013779:Tetrodotoxin / Q000494:pharmacology; D020692:rab3 GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D018091:Receptors, AMPA; C491490:Rims1 protein, mouse; D026941:Sodium Channel Blockers; D013779:Tetrodotoxin; D019204:GTP-Binding Proteins; C475524:Rim2 protein, mouse; D020692:rab3 GTP-Binding Proteins; C104722:glutamate receptor ionotropic, AMPA 2
keywords: GluA2; RIM1/2; mouse; synaptic vesicles; tetrodotoxin