title: Synapse composition and organization following chronic activity blockade in cultured hippocampal neurons.
abstract: Activity plays multiple roles in the expression of synaptic plasticity, and has been shown to regulate the localization of both neurotransmitter receptors and downstream signaling machinery. However, the role of activity in central synapse formation and organization is incompletely understood. Some studies indicate that synapse formation can occur in the absence of synaptic activity, while others indicate that activity is required for synapse maintenance and receptor recruitment. In addition, the effects of long-term blockade of transmission generally, rather than blockade of specific receptors, on postsynaptic protein complement has been poorly characterized. In order to address the role of activity in synapse formation and postsynaptic specialization, we used tetanus toxin to chronically cleave VAMP2 and inhibit SNARE-mediated neurotransmitter release in cultured hippocampal neurons. Although these neurons are deficient in synaptic release, they are of normal size and morphology. In addition, both excitatory and inhibitory synapses form along their processes with normal density. These synapses have a remarkably similar cellular and molecular organization compared to controls, and are capable of recruiting postsynaptic scaffolding proteins, GABA, and glutamate receptors. Subcellular enrichment of synaptic proteins into specialized domains also appears intact. These data indicate that global activity inhibition is insufficient to disrupt central synapse formation or organization.
authors.affiliation: Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
authors.forename: Kimberly J
authors.initials: KJ
authors.lastname: Harms
authors.forename: Ann Marie
authors.initials: AM
authors.lastname: Craig
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D002478:Cells, Cultured; D003712:Dendrites / Q000378:metabolism; D004622:Embryo, Mammalian; D020690:GTPase-Activating Proteins / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects*; D005968:Glutamate Decarboxylase / Q000378:metabolism; D006624:Hippocampus / Q000166:cytology*; D007150:Immunohistochemistry / Q000379:methods; D008565:Membrane Proteins / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009433:Neural Inhibition / Q000187:drug effects; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D050683:R-SNARE Proteins; D051381:Rats; D017207:Rats, Sprague-Dawley; D011963:Receptors, GABA-A / Q000378:metabolism; D017470:Receptors, Glutamate / Q000378:metabolism; D013569:Synapses / Q000187:drug effects*; D016704:Synapsins / Q000378:metabolism; D009435:Synaptic Transmission / Q000187:drug effects; D013744:Tetanus Toxin / Q000494:pharmacology*; D013779:Tetrodotoxin / Q000494:pharmacology*; D050598:Vesicular Glutamate Transport Protein 1
chemical_list: D002352:Carrier Proteins; D020690:GTPase-Activating Proteins; C489787:MAP2 protein, rat; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D008869:Microtubule-Associated Proteins; D009419:Nerve Tissue Proteins; D050683:R-SNARE Proteins; D011963:Receptors, GABA-A; D017470:Receptors, Glutamate; D016704:Synapsins; C112202:Syngap1 protein, rat; D013744:Tetanus Toxin; D050598:Vesicular Glutamate Transport Protein 1; C073441:gephyrin; C033652:postsynaptic density proteins; D013779:Tetrodotoxin; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D005968:Glutamate Decarboxylase