Central connectivity of transient receptor potential melastatin 8-expressing axons in the brain stem and spinal dorsal horn.

Transient receptor potential melastatin 8 (TRPM8) ion channels mediate the detection of noxious and innocuous cold and are expressed by primary sensory neurons, but little is known about the processing of the TRPM8-mediated cold information within the trigeminal sensory nuclei (TSN) and the spinal d...

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Main Authors: Yun Sook Kim, Jun Hong Park, Su Jung Choi, Jin Young Bae, Dong Kuk Ahn, David D McKemy, Yong Chul Bae
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2014-01-01
Series:PLoS ONE
Online Access:http://europepmc.org/articles/PMC3977991?pdf=render
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spelling doaj-21cd31da27b74ff39d56f639f36375062020-11-25T00:47:27ZengPublic Library of Science (PLoS)PLoS ONE1932-62032014-01-0194e9408010.1371/journal.pone.0094080Central connectivity of transient receptor potential melastatin 8-expressing axons in the brain stem and spinal dorsal horn.Yun Sook KimJun Hong ParkSu Jung ChoiJin Young BaeDong Kuk AhnDavid D McKemyYong Chul BaeTransient receptor potential melastatin 8 (TRPM8) ion channels mediate the detection of noxious and innocuous cold and are expressed by primary sensory neurons, but little is known about the processing of the TRPM8-mediated cold information within the trigeminal sensory nuclei (TSN) and the spinal dorsal horn (DH). To address this issue, we characterized TRPM8-positive (+) neurons in the trigeminal ganglion and investigated the distribution of TRPM8+ axons and terminals, and their synaptic organization in the TSN and in the DH using light and electron microscopic immunohistochemistry in transgenic mice expressing a genetically encoded axonal tracer in TRPM8+ neurons. TRPM8 was expressed in a fraction of small myelinated primary afferent fibers (23.7%) and unmyelinated fibers (76.3%), suggesting that TRPM8-mediated cold is conveyed via C and Aδ afferents. TRPM8+ axons were observed in all TSN, but at different densities in the dorsal and ventral areas of the rostral TSN, which dominantly receive sensory afferents from intra- and peri-oral structures and from the face, respectively. While synaptic boutons arising from Aδ and non-peptidergic C afferents usually receive many axoaxonic contacts and form complex synaptic arrangements, TRPM8+ boutons arising from afferents of the same classes of fibers showed a unique synaptic connectivity; simple synapses with one or two dendrites and sparse axoaxonic contacts. These findings suggest that TRPM8-mediated cold is conveyed via a specific subset of C and Aδ afferent neurons and is processed in a unique manner and differently in the TSN and DH.http://europepmc.org/articles/PMC3977991?pdf=render
collection DOAJ
language English
format Article
sources DOAJ
author Yun Sook Kim
Jun Hong Park
Su Jung Choi
Jin Young Bae
Dong Kuk Ahn
David D McKemy
Yong Chul Bae
spellingShingle Yun Sook Kim
Jun Hong Park
Su Jung Choi
Jin Young Bae
Dong Kuk Ahn
David D McKemy
Yong Chul Bae
Central connectivity of transient receptor potential melastatin 8-expressing axons in the brain stem and spinal dorsal horn.
PLoS ONE
author_facet Yun Sook Kim
Jun Hong Park
Su Jung Choi
Jin Young Bae
Dong Kuk Ahn
David D McKemy
Yong Chul Bae
author_sort Yun Sook Kim
title Central connectivity of transient receptor potential melastatin 8-expressing axons in the brain stem and spinal dorsal horn.
title_short Central connectivity of transient receptor potential melastatin 8-expressing axons in the brain stem and spinal dorsal horn.
title_full Central connectivity of transient receptor potential melastatin 8-expressing axons in the brain stem and spinal dorsal horn.
title_fullStr Central connectivity of transient receptor potential melastatin 8-expressing axons in the brain stem and spinal dorsal horn.
title_full_unstemmed Central connectivity of transient receptor potential melastatin 8-expressing axons in the brain stem and spinal dorsal horn.
title_sort central connectivity of transient receptor potential melastatin 8-expressing axons in the brain stem and spinal dorsal horn.
publisher Public Library of Science (PLoS)
series PLoS ONE
issn 1932-6203
publishDate 2014-01-01
description Transient receptor potential melastatin 8 (TRPM8) ion channels mediate the detection of noxious and innocuous cold and are expressed by primary sensory neurons, but little is known about the processing of the TRPM8-mediated cold information within the trigeminal sensory nuclei (TSN) and the spinal dorsal horn (DH). To address this issue, we characterized TRPM8-positive (+) neurons in the trigeminal ganglion and investigated the distribution of TRPM8+ axons and terminals, and their synaptic organization in the TSN and in the DH using light and electron microscopic immunohistochemistry in transgenic mice expressing a genetically encoded axonal tracer in TRPM8+ neurons. TRPM8 was expressed in a fraction of small myelinated primary afferent fibers (23.7%) and unmyelinated fibers (76.3%), suggesting that TRPM8-mediated cold is conveyed via C and Aδ afferents. TRPM8+ axons were observed in all TSN, but at different densities in the dorsal and ventral areas of the rostral TSN, which dominantly receive sensory afferents from intra- and peri-oral structures and from the face, respectively. While synaptic boutons arising from Aδ and non-peptidergic C afferents usually receive many axoaxonic contacts and form complex synaptic arrangements, TRPM8+ boutons arising from afferents of the same classes of fibers showed a unique synaptic connectivity; simple synapses with one or two dendrites and sparse axoaxonic contacts. These findings suggest that TRPM8-mediated cold is conveyed via a specific subset of C and Aδ afferent neurons and is processed in a unique manner and differently in the TSN and DH.
url http://europepmc.org/articles/PMC3977991?pdf=render
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