title: Presynaptically silent synapses studied with light microscopy.
abstract: Synaptic plasticity likely underlies the nervous system's ability to learn and remember and may also represent an adaptability that prevents otherwise damaging insults from becoming neurotoxic. We have been studying a form of presynaptic plasticity that is interesting in part because it is expressed as a digital switching on and off of a presynaptic terminal s ability to release vesicles containing the neurotransmitter glutamate. Here we demonstrate a protocol for visualizing the activity status of presynaptic terminals in dissociated cell cultures prepared from the rodent hippocampus. The method relies on detecting active synapses using staining with a fixable form of the styryl dye FM1-43, commonly used to label synaptic vesicles. This staining profile is compared with immunostaining of the same terminals with an antibody directed against the vesicular glutamate transporter 1 (vGluT-1), a stain designed to label all glutamate synapses regardless of activation status. We find that depolarizing stimuli induce presynaptic silencing. The population of synapses that is silent under baseline conditions can be activated by prolonged electrical silencing or by activation of cAMP signaling pathways.
authors.affiliation: Department of Psychiatry, Washington University School of Medicine, USA.
authors.forename: Krista L
authors.initials: KL
authors.lastname: Moulder
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Jiang
authors.forename: Amanda A
authors.initials: AA
authors.lastname: Taylor
authors.forename: Ann M
authors.initials: AM
authors.lastname: Benz
authors.forename: Steven
authors.initials: S
authors.lastname: Mennerick
mesh_terms: D000818:Animals; D000906:Antibodies / Q000737:chemistry; D002478:Cells, Cultured; D023902:Chromosome Pairing / Q000502:physiology*; D018698:Glutamic Acid / Q000502:physiology; D006624:Hippocampus / Q000166:cytology; D008027:Light; D051379:Mice; D008853:Microscopy / Q000379:methods*; D009473:Neuronal Plasticity / Q000502:physiology*; D051381:Rats; D013194:Staining and Labeling / Q000379:methods; D050598:Vesicular Glutamate Transport Protein 1 / Q000276:immunology
chemical_list: D000906:Antibodies; D050598:Vesicular Glutamate Transport Protein 1; D018698:Glutamic Acid