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Front. Neuroanat. | doi: 10.3389/fnana.2018.00015

TRPC1 channels are expressed in pyramidal neurons and in a subset of somatostatin interneurons in the rat neocortex

  • 1Instituto de Investigación en Discapacidades Neurológicas/Facultad de Medicina, Universidad de Castilla La Mancha Albacete, Spain

Disturbances in calcium homeostasis due to canonical transient receptor potential (TRPC) and/or store-operated calcium (SOC) channels can play a key role in a large number of brain disorders. TRPC channels are plasma membrane cation channels included in the transient receptor potential (TRP) superfamily. The most widely distributed member of the TRPC subfamily in the brain is TRPC1, which is frequently linked to group I metabotropic glutamate receptors (mGluRs) and to the components of SOC channels. Proposing TRPC/SOC channels as a therapeutic target in neurological diseases previously requires a detailed knowledge of the distribution of such molecules in the brain. The aim of our study was to analyze the neuroanatomical distribution of TRPC1 in the rat neocortex. By double- and triple-labeling and confocal microscopy, we tested the presence of TRPC1 by using a series of specific neurochemical markers. TRPC1 was abundant in SMI 32-positive pyramidal neurons, and in some GAD67 interneurons, but was lacking in GFAP-positive glial cells. In neurons it colocalized with postsynaptic marker MAP2 in cell bodies and apical dendritic trunks and it was virtually absent in synaptophysin-immunoreactive terminals. By using a panel of antibodies to classify interneurons, we identified the GABAergic interneurons that contained TRPC1. TRPC1 was lacking in basket and chandelier parvalbumin (PVALB) cells, and a very low percentage of calretinin (CALR) or calbindin (CALB) interneurons expressed TRPC1. Moreover, 63% of somatostatin (SST) expressing-cells and 37% of reelin-positive cells expressed TRPC1. All the SST/TRPC1 double-labeled cells, many of which were presumptive Martinotti cells (MC), were positive for reelin. The presence of TRPC1 in the somata and apical dendritic trunks of neocortical pyramidal cells suggests a role for this channel in sensory processing and synaptic plasticity. Conversely in SST/reelin interneurons, TRPC1 could modulate GABAergic transmission, which is responsible for shaping the coordinated activity of the pyramidal cells in the cortical network. In future studies, it would be relevant to investigate whether TRPC1 could be involved in the expression or processing of reelin in SST inhibitory interneurons.

Keywords: TRPC1, Somatosensory Cortex, Pyramidal neurons, Somatostatin Interneurons, Martinotti cells

Received: 13 Dec 2017; Accepted: 09 Feb 2018.

Edited by:

Alberto Munoz, Complutense University of Madrid, Spain

Reviewed by:

Eduard Korkotian, Weizmann Institute of Science, Israel
Francisco Javier Martin-Romero, University of Extremadura, Spain  

Copyright: © 2018 Martinez-Galan, Verdejo and Caminos. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: PhD. Juan R. Martinez-Galan, Universidad de Castilla La Mancha Albacete, Instituto de Investigación en Discapacidades Neurológicas/Facultad de Medicina, C/ Almansa, 14., Albacete, 02008, Albacete, Spain, JuanRamon.Martinez@uclm.es