title: Segregation and coactivation of developing neocortical layer 1 neurons.
abstract: Layer 1 in the developing cerebral cortex is populated by two basic neuronal cell types, Cajal-Retzius (CR) cells and non-CR cells. We generated transgenic mice in which green fluorescent protein (GFP) was driven by the promoter of metabotropic glutamate receptor subtype 2 and expressed specifically in CR cells during cortical development. On the basis of the precise identification of CR cells with GFP fluorescence, we pursued developmental changes and synaptic mechanisms of both CR and non-CR cells during the postnatal period. Immunostaining in combination with GFP fluorescence imaging showed that GFP and reelin, a protein involved in corticogenesis, completely overlap in CR cells at postnatal day 0. At the subsequent postnatal stage, reelin-positive neurons are segregated and categorized into GFP-positive/GABA-negative CR cells and GFP-negative/GABA-positive non-CR cells. Individual and simultaneous whole-cell recordings of CR and non-CR cells in developing cerebral slices revealed that spontaneous and electrically evoked postsynaptic currents (sPSCs and ePSCs) measured in CR and non-CR cells are differentially mediated by GABA(A) receptors versus GABA(A), AMPA, and NMDA receptors, respectively. Furthermore, CR and non-CR cells show synchronized repetitive barrages of sPSCs that reflect a network-driven activity in the developing cerebral cortex. These findings imply that the layer 1 neurons dynamically change and play a distinct and integral role in the postnatal developing neocortex.
authors.affiliation: Department of Biological Sciences, Kyoto University Faculty of Medicine, Kyoto University Graduate School of Biostudies, Kyoto 606-8501, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Soda
authors.forename: Ryo
authors.initials: R
authors.lastname: Nakashima
authors.forename: Dai
authors.initials: D
authors.lastname: Watanabe
authors.forename: Kazunori
authors.initials: K
authors.lastname: Nakajima
authors.forename: Ira
authors.initials: I
authors.lastname: Pastan
authors.forename: Shigetada
authors.initials: S
authors.lastname: Nakanishi
mesh_terms: D000818:Animals; D015816:Cell Adhesion Molecules, Neuronal / Q000096:biosynthesis; D004558:Electric Stimulation; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D016326:Extracellular Matrix Proteins / Q000096:biosynthesis; D018756:GABA Antagonists / Q000494:pharmacology; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins; D006801:Humans; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D008164:Luminescent Proteins / Q000235:genetics; D051379:Mice; D019579:Neocortex / Q000166:cytology / Q000254:growth & development* / Q000502:physiology*; D009419:Nerve Tissue Proteins; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D015375:Receptors, Interleukin-2 / Q000235:genetics; D018094:Receptors, Metabotropic Glutamate / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000235:genetics; D000091042:Reelin Protein; D012697:Serine Endopeptidases; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology
chemical_list: D015816:Cell Adhesion Molecules, Neuronal; D018691:Excitatory Amino Acid Antagonists; D016326:Extracellular Matrix Proteins; D018756:GABA Antagonists; D008164:Luminescent Proteins; D009419:Nerve Tissue Proteins; D015375:Receptors, Interleukin-2; D018094:Receptors, Metabotropic Glutamate; D011993:Recombinant Fusion Proteins; D000091042:Reelin Protein; C108822:metabotropic glutamate receptor 2; D049452:Green Fluorescent Proteins; C000717127:RELN protein, human; C000717128:Reln protein, mouse; D012697:Serine Endopeptidases