Molecular identity of dendritic voltage-gated sodium channels in CA1 pyramidal cells

Abstract

Event Abstract Back to Event Molecular identity of dendritic voltage-gated sodium channels in CA1 pyramidal cells Andrea Lorincz1* and Zoltán Nusser1 1 Hungarian Academy of Sciences, Laboratory of Cellular Neurophysiology, Institute of Experimental Medicine, Hungary High density of voltage-gated sodium (Nav) channels in axon initial segments (AIS) of pyramidal cells (PC) ensures low threshold for the initiation of action potential (AP). Nav channels-mediated currents were found in the somato-dendritic domain of PCs, where they contribute to dendritic spikes and backpropagating APs. However, the molecular identity of somato-dendritic Nav channels is unknown, most likely owing to the limited sensitivity of the applied methods. Here we used immunofluorescent reactions and a highly sensitive electron microscopic SDS-digested freeze-fracture replica-labeling (SDS-FRL) technique to identify the Nav subunit content of the axo-somato-dendritic plasma membranes of CA1 pyramidal cells (PCs). Modified immunofluorescent reactions with a pan-Nav antibody demonstrated the presence of Nav channels in the axo-somato-dendritic compartments of CA1 PCs, but the method failed to detect Nav1.1, Nav1.2 or Nav1.6 subunits on the somato-dendritic surface of CA1 PCs. Using SDS-FRL, high densities of gold particles for the Nav1.6 subunit were detected in Nodes of Ranvier and AISs of CA1 PCs. We found a graded increase in the density of gold particles along the proximo-distal axis of AISs and the gold particles consistently avoided GABAergic axo-axonic synapses. Somatic and dendritic plasma membranes also contained gold particles for the Nav1.6 subunit at low, but significant densities. However, we could not detect gold particles in dendritic spines. Quantitative analysis revealed that AISs contained ~40-fold higher density of gold particles than somatic and proximal dendritic plasma membranes. A distance dependent decrease in the density of gold particles was also observed along the proximo-distal axis of the dendrites. Our results demonstrate for the first time the somato-dendritic presence of the Nav1.6 subunit and reveal quantitative differences in the amount of the Nav1.6 subunit between different subcellular compartments of CA1 PCs. Conference: IBRO International Workshop 2010, Pécs, Hungary, 21 Jan - 23 Jan, 2010. Presentation Type: Poster Presentation Topic: Cellular neuroscience Citation: Lorincz A and Nusser Z (2010). Molecular identity of dendritic voltage-gated sodium channels in CA1 pyramidal cells. Front. Neurosci. Conference Abstract: IBRO International Workshop 2010. doi: 10.3389/conf.fnins.2010.10.00078 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 21 Apr 2010; Published Online: 21 Apr 2010. * Correspondence: Andrea Lorincz, Hungarian Academy of Sciences, Laboratory of Cellular Neurophysiology, Institute of Experimental Medicine, Budapest, Hungary, lorincz@koki.hu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Andrea Lorincz Zoltán Nusser Google Andrea Lorincz Zoltán Nusser Google Scholar Andrea Lorincz Zoltán Nusser PubMed Andrea Lorincz Zoltán Nusser Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.