title: Glutamate induces the rapid formation of spine head protrusions in hippocampal slice cultures.
abstract: Synaptic plasticity at neuronal connections has been well characterized functionally by using electrophysiological approaches, but the structural basis for this phenomenon remains controversial. We have studied the dynamic interactions between presynaptic and postsynaptic structures labeled with FM 4-64 and a membrane-targeted GFP, respectively, in hippocampal slices. Under conditions of reduced neuronal activity (1 muM tetrodotoxin), we observed extension of glutamate receptor-dependent processes from dendritic spines of CA1 pyramidal cells to presynaptic boutons. The formation of these spine head protrusions is blocked by alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor antagonists and by agents that reduce the release of glutamate from presynaptic terminals. Moreover, spine head protrusions form in response to exogenously applied glutamate, with clear directionality toward the glutamate electrode. Our results suggest that spontaneously released glutamate is sufficient to activate nearby spines, which can then lead to the growth of new postsynaptic processes connecting to a presynaptic site. Spines thus can compare their recent history with that of neighboring synapses and modify local connectivity accordingly.
authors.affiliation: Brain Research Institute, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
authors.forename: David A
authors.initials: DA
authors.lastname: Richards
authors.forename: José Maria
authors.initials: JM
authors.lastname: Mateos
authors.forename: Sylvain
authors.initials: S
authors.lastname: Hugel
authors.forename: Vincenzo
authors.initials: V
authors.lastname: de Paola
authors.forename: Pico
authors.initials: P
authors.lastname: Caroni
authors.forename: Beat H
authors.initials: BH
authors.lastname: Gähwiler
authors.forename: R Anne
authors.initials: RA
authors.lastname: McKinney
mesh_terms: D000818:Animals; D003712:Dendrites / Q000187:drug effects / Q000648:ultrastructure; D018698:Glutamic Acid / Q000494:pharmacology*; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D007091:Image Processing, Computer-Assisted; D007700:Kinetics; D051379:Mice; D016202:N-Methylaspartate / Q000494:pharmacology; D009924:Organ Culture Techniques; D017966:Pyramidal Cells / Q000166:cytology / Q000187:drug effects / Q000648:ultrastructure; D011810:Quinoxalines / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology
chemical_list: D011810:Quinoxalines; C062865:2,3-dioxo-6-nitro-7-sulfamoylbenzo(f)quinoxaline; D018698:Glutamic Acid; D013779:Tetrodotoxin; D016202:N-Methylaspartate