title: Left-right asymmetry of the hippocampal synapses with differential subunit allocation of glutamate receptors.
abstract: Left-right asymmetry of the brain has been studied mostly through psychological examination and functional imaging in primates, leaving its molecular and synaptic aspects largely unaddressed. Here, we show that hippocampal CA1 pyramidal cell synapses differ in size, shape, and glutamate receptor expression depending on the laterality of presynaptic origin. CA1 synapses receiving neuronal input from the right CA3 pyramidal cells are larger and have more perforated PSD and a GluR1 expression level twice as high as those receiving input from the left CA3. The synaptic density of GluR1 increases as the size of a synapse increases, whereas that of NR2B decreases because of the relatively constant NR2B expression in CA1 regardless of synapse size. Densities of other major glutamate receptor subunits show no correlation with synapse size, thus resulting in higher net expression in synapses having right input. Our study demonstrates universal left-right asymmetry of hippocampal synapses with a fundamental relationship between synaptic area and the expression of glutamate receptor subunits.
authors.affiliation: Division of Cerebral Structure, National Institute for Physiological Sciences, Okazaki 444-8787, Japan. shinohara@brain.riken.jp
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Shinohara
authors.forename: Hajime
authors.initials: H
authors.lastname: Hirase
authors.forename: Masahiko
authors.initials: M
authors.lastname: Watanabe
authors.forename: Makoto
authors.initials: M
authors.lastname: Itakura
authors.forename: Masami
authors.initials: M
authors.lastname: Takahashi
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Shigemoto
mesh_terms: D000818:Animals; D007839:Functional Laterality / Q000502:physiology*; D006624:Hippocampus / Q000166:cytology* / Q000378:metabolism*; D051379:Mice; D017966:Pyramidal Cells / Q000378:metabolism*; D018091:Receptors, AMPA / Q000378:metabolism; D017470:Receptors, Glutamate / Q000378:metabolism*; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism; D013569:Synapses / Q000378:metabolism
chemical_list: D018091:Receptors, AMPA; D017470:Receptors, Glutamate; D016194:Receptors, N-Methyl-D-Aspartate; C409466:NR1 NMDA receptor; C120997:NR2A NMDA receptor; C121001:NR2B NMDA receptor; C104723:glutamate receptor ionotropic, AMPA 3; C104722:glutamate receptor ionotropic, AMPA 2