title: Solubilization and immunological identification of presynaptic alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors in the rat hippocampus.
abstract: Alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors have been identified mostly as postsynaptic receptors mediating fast glutamatergic synaptic transmission. However, neurochemical studies based on the modulation of neurotransmitter release have suggested the existence of presynaptic AMPA receptors. We have used a recently described technique that allows a high-purity fractionation of the pre- and postsynaptic proteins of synaptic junctions to evaluate the distribution of the different AMPA receptor subunits in rat hippocampal synapses. Surprisingly, we found very high levels of GluR1- and GluR2/3-like immunoreactivity in the presynaptic fraction, but also in the postsynaptic and extrasynaptic fractions. GluR4-like immunoreactivity was much less abundant but was still detected, predominantly in the postsynaptic fraction. This methodology appears to be far more sensitive than the classical immunogold electron microscopy to determine the localization of synaptic receptors.
authors.affiliation: Center for Neuroscience and Cell Biology of Coimbra, Institute of Biochemistry, Faculty of Medicine, University of Coimbra, 3004-504 Coimbra, Portugal.
authors.forename: Paulo S
authors.initials: PS
authors.lastname: Pinheiro
authors.forename: Ricardo J
authors.initials: RJ
authors.lastname: Rodrigues
authors.forename: Ana P
authors.initials: AP
authors.lastname: Silva
authors.forename: Rodrigo A
authors.initials: RA
authors.lastname: Cunha
authors.forename: Catarina R
authors.initials: CR
authors.lastname: Oliveira
authors.forename: João O
authors.initials: JO
authors.lastname: Malva
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002458:Cell Fractionation; D006624:Hippocampus / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D051381:Rats; D018091:Receptors, AMPA / Q000032:analysis / Q000145:classification* / Q000378:metabolism*; D017981:Receptors, Neurotransmitter / Q000032:analysis / Q000145:classification / Q000378:metabolism; D017661:Receptors, Presynaptic / Q000032:analysis / Q000378:metabolism*; D012995:Solubility; D013570:Synaptic Membranes / Q000378:metabolism; D013574:Synaptosomes / Q000378:metabolism*
chemical_list: D018091:Receptors, AMPA; D017981:Receptors, Neurotransmitter; D017661:Receptors, Presynaptic