title: Proximity of excitatory synapses and astroglial gap junctions in layer IV of the mouse barrel cortex.
abstract: Neurons and astrocytes, the two major cell populations in the adult brain, are characterized by their own mode of intercellular communication--the synapses and the gap junctions (GJ), respectively. In addition, there is increasing evidence for dynamic and metabolic neuroglial interactions resulting in the modulation of synaptic transmission at the so-called "tripartite synapse". Based on this, we have investigated at the ultrastructural level how excitatory synapses (ES) and astroglial GJ are spatially distributed in layer IV of the barrel cortex of the adult mouse. We used specific antibodies for connexin (Cx) 30 and 43 to identify astroglial GJ, these two proteins are known to be present in the majority of astroglial GJ in the cerebral cortex. In electron-microscopic images, we measured the distance between two ES, between two GJ and between a GJ and its nearest ES. We found a ratio of two GJ per three ES in the hollow and septal areas. Taking into account the size of an astrocyte domain, the high density of GJ suggests the occurrence of reflexive type, i.e. GJ between processes of the same astrocyte. Interestingly, the distance between an ES and an astroglial GJ was found to be significantly lower than that between either two synapses or between two GJ. These observations indicate that the two modes of cell-to-cell communication are not randomly distributed in layer IV of the barrel cortex. Consequently, this feature may provide the morphological support for the recently reported functional interactions between neuronal circuits and astroglial networks.
authors: Département de Neurosciences Fondamentales, University of Lausanne, 1005 Lausanne, Switzerland; Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland.
authors: C
authors: C
authors: Genoud
authors: Collège de France, Center for Interdisciplinary Research in Biology (CIRB), France; Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7241, France; Institut National de la Santé et de la Recherche Médicale U1050, 75231 Paris Cedex 05, France; University Pierre et Marie Curie, ED, N°158, 75005 Paris, France; MEMOLIFE Laboratory of Excellence and Paris Science Lettre Research University, 75005 Paris, France.
authors: V
authors: V
authors: Houades
authors: Département de Neurosciences Fondamentales, University of Lausanne, 1005 Lausanne, Switzerland.
authors: R
authors: R
authors: Kraftsik
authors: Département de Neurosciences Fondamentales, University of Lausanne, 1005 Lausanne, Switzerland. Electronic address: egbert.welker@unil.ch.
authors: E
authors: E
authors: Welker
authors: Collège de France, Center for Interdisciplinary Research in Biology (CIRB), France; Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7241, France; Institut National de la Santé et de la Recherche Médicale U1050, 75231 Paris Cedex 05, France; University Pierre et Marie Curie, ED, N°158, 75005 Paris, France; MEMOLIFE Laboratory of Excellence and Paris Science Lettre Research University, 75005 Paris, France. Electronic address: christian.giaume@college-de-france.fr.
authors: C
authors: C
authors: Giaume
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000378:metabolism / Q000648:ultrastructure*; D000075302:Connexin 30; D018031:Connexin 43 / Q000378:metabolism; D017630:Connexins / Q000378:metabolism; D017629:Gap Junctions / Q000378:metabolism / Q000648:ultrastructure*; D007150:Immunohistochemistry; D051379:Mice; D008854:Microscopy, Electron; D009474:Neurons / Q000378:metabolism / Q000648:ultrastructure*; D013003:Somatosensory Cortex / Q000378:metabolism / Q000648:ultrastructure*; D013569:Synapses / Q000378:metabolism / Q000648:ultrastructure*; D014738:Vibrissae
chemical_list: D000075302:Connexin 30; D018031:Connexin 43; D017630:Connexins; C543076:GJA1 protein, mouse; C100629:Gjb6 protein, mouse
keywords: astrocyte; connexins; glia; somatosensory cortex