同: DRG

同: DRG

WordNet

plant by the roots
(botany) the usually underground organ that lacks buds or leaves or nodes; absorbs water and mineral salts; usually it anchors the plant to the ground
a number that, when multiplied by itself some number of times, equals a given number
cause to take roots
take root and begin to grow; "this plant roots quickly"
(linguistics) the form of a word after all affixes are removed; "thematic vowels are part of the stem" (同)root word, base, stem, theme, radical
the part of a tooth that is embedded in the jaw and serves as support (同)tooth_root
come into existence, originate; "The problem roots in her depression"
belonging to or on or near the back or upper surface of an animal or organ or part; "the dorsal fin is the vertical fin on the back of a fish and certain marine mammals"
the condition of belonging to a particular place or group by virtue of social or ethnic or cultural lineage; "his roots in Texas go back a long way"; "he went back to Sweden to search for his roots"; "his music has African roots"

PrepTutorEJDIC

《しばしば複数形で》『根』 / 『根元』 / 《the~》『根源』,根本;根底 / 《複数形で》(その人の根底にある)ある場所との根源的なつながり / (数学で)根,ルート / (派生語の)語根(例えばrootlessの中のroot) / 〈植物〉‘を'『根づかせる』 / 《しばしば受動態で》(根をおろしたように)(…に)…‘を'『定着させる』『+『名』+『to』(『in』)+『名』》 / (…に)『根を下ろす』,定着する《+『in』(『on』,『to』)+『名』》
〈豚などが〉(…をあさって)鼻で地面を掘る《+『about』(『around』)『for』+『名』》 / (…を捜して)〈人が〉かき回す《+『about for』+『名』》
(…を)声援する,(…の)成功を願う《+『for』+『名』》
(植物の)背部の,背の
《補語にのみ用いて》(植物が)根づいた / (考えなどが)定着した

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/06/29 17:00:37」(JST)

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[Wiki en表示]

A posterior root ganglion (or spinal ganglion) (also known as a dorsal root ganglion), is a cluster of nerve cell bodies (a ganglion) in a posterior root of a spinal nerve.

Structure

The axons of posterior root ganglion neurons are known as afferents. In the peripheral nervous system, afferents refer to the axons that relay sensory information into the central nervous system (i.e. the brain and the spinal cord). These neurons are of the pseudo-unipolar type, meaning they have an axon with two branches that act as a single axon, often referred to as a distal process and a proximal process.

Note: the neuron can consist of three parts:

1. Dendrite that receives the information and relays it to the Soma, or cell body.
2. Soma - the cell body of the neuron
3. Axon: which relays information from the soma.

In a neuron, the dendrite receives information from another neuron's axon at the synapse, and the axon sends information to the next neuron's dendrites, even though the dendrite may be covered with myelin.

Unlike the majority of neurons found in the central nervous system, an action potential in posterior root ganglion neuron may initiate in the distal process in the periphery, bypass the cell body, and continue to propagate along the proximal process until reaching the synaptic terminal in the posterior horn of spinal cord.

Distal section

The distal section of the axon may either be a bare nerve ending or encapsulated by a structure that helps relay specific information to nerve. For example, a Meissner's corpuscle or Pacinian corpuscle may encapsulate the nerve ending, rendering the distal process sensitive to mechanical stimulation, such as stroking or vibration, respectively.^[1]

Location

The posterior root ganglia lie along the vertebral column by the spine.

Development

The posterior root ganglia develops in the embryo from neural crest cells, not neural tube. Hence, the spinal ganglia can be regarded as gray matter of the spinal cord that became translocated to the periphery.

Function

Nociception

Proton-sensing G protein-coupled receptors are expressed by DRG sensory neurons and might play a role in acid-induced nociception.^[2]

Mechanosensitive channels

The nerve endings of posterior root ganglion neurons have a variety of sensory receptors that are activated by mechanical, thermal, chemical, and noxious stimuli.^[3] In these sensory neurons, a group of ion channels thought to be responsible for somatosensory transduction have been identified. Compression of the dorsal root ganglion by a mechanical stimulus lowers the voltage threshold needed to evoke a response and causes action potentials to be fired.^[4] This firing may even persist after the removal of the stimulus.^[4]

Two distinct types of mechanosensitive ion channels have been found in the posterior root ganglion neurons. The two channels are broadly classified as either high-threshold (HT) or low threshold (LT) .^[3] As their names suggest, they have different thresholds as well as different sensitivities to pressure. These are cationic channels whose activity appears to be regulated by the proper functioning of the cytoskeleton and cytoskeleton associated proteins.^[3] The presence of these channels in the posterior root ganglion gives reason to believe that other sensory neurons may contain them as well.

High-threshold mechanosensitive channels

High-threshold channels have a possible role in nociception. These channels are found predominantly in smaller sensory neurons in the posterior root ganglion cells and are activated by higher pressures, two attributes that are characteristic of nociceptors.^[3] Also, the threshold of HT channels was lowered in the presence of PGE2 (a compound that sensitizes neurons to mechanical stimuli and mechanical hyperalgesia) which further supports a role for HT channels in the transduction of mechanical stimuli into nociceptive neuronal signals.^[3]^[4]^[5]

Presynaptic control

The presynaptic regulation of the dorsal nerve ending discharge in the spinal cord can occur through certain types of GABA_A receptors but not through the activation of glycine receptors which are absent from these types of terminals. Thus GABA_A receptors but not glycine receptors can presynaptically control nociception and pain transmission. ^[6]

References

^ Kandel ER, Schwartz JH, Jessell TM. Principles of Neural Science, 4th ed., p.431-433. McGraw-Hill, New York (2000). ISBN 0-8385-7701-6
^ Huang CW, Tzeng JN, Chen YJ, Tsai WF, Chen CC, Sun WH (2007). "Nociceptors of dorsal root ganglion express proton-sensing G-protein-coupled receptors". Mol. Cell. Neurosci. 36 (2): 195–210. doi:10.1016/j.mcn.2007.06.010. PMID 17720533.
^ ^a ^b ^c ^d ^e Cho, H.; Shin, J.; Shin, C. Y.; Lee, S. Y.; Oh, U. (2002). "Mechanosensitive ion channels in cultured sensory neurons of neonatal rats". The Journal of neuroscience : the official journal of the Society for Neuroscience 22 (4): 1238–1247. PMID 11850451. edit
^ ^a ^b ^c Sugawara, O.; Atsuta, Y.; Iwahara, T.; Muramoto, T.; Watakabe, M.; Takemitsu, Y. (1996). "The effects of mechanical compression and hypoxia on nerve root and dorsal root ganglia. An analysis of ectopic firing using an in vitro model". Spine 21 (18): 2089–2094. doi:10.1097/00007632-199609150-00006. PMID 8893432. edit
^ Syriatowicz, J. P.; Hu, D.; Walker, J. S.; Tracey, D. J. (1999). "Hyperalgesia due to nerve injury: Role of prostaglandins". Neuroscience 94 (2): 587–594. doi:10.1016/S0306-4522(99)00365-6. PMID 10579219. edit
^ Lorenzo LE, Godin AG, Wang F, St-Louis M, Carbonetto S, Wiseman PW, Ribeiro-da-Silva A, De Koninck Y (June 2014). "Gephyrin Clusters Are Absent from Small Diameter Primary Afferent Terminals Despite the Presence of GABA_A Receptors". J. Neurosci. 34 (24): 8300–17. doi:10.1523/JNEUROSCI.0159-14.2014. PMID 24920633.

Additional images

Medulla spinalis
The formation of the spinal nerve from the posterior and anterior roots |
Scheme showing structure of a typical spinal nerve.

External links

Anatomy figure: 02:04-09 at Human Anatomy Online, SUNY Downstate Medical Center
Histology image: 04401loa – Histology Learning System at Boston University
Photo of model at Ohio State University
Diagram at webanatomy.net
Photo at uwlax.edu

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English Journal

Melanocortin-4 receptor expression in different classes of spinal and vagal primary afferent neurons in the mouse.

Gautron L, Lee CE, Lee S, Elmquist JK.SourceDepartment of Internal Medicine, Division of Hypothalamic Research, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9077. Laurent.Gautron@UTSouthwestern.edu.
The Journal of comparative neurology.J Comp Neurol.2012 Dec 1;520(17):3933-48. doi: 10.1002/cne.23137.
Melanocortin-4 receptor (MC4R) ligands are known to modulate nociception, but the site of action of MC4R signaling on nociception remains to be elucidated. The current study investigated MC4R expression in dorsal root ganglia (DRG) of the MC4R-GFP reporter mouse. Because MC4R is known to be expresse
PMID 22592759

Selective distribution of GABA(A) receptor subtypes in mouse spinal dorsal horn neurons and primary afferents.

Paul J, Zeilhofer HU, Fritschy JM.SourceInstitute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zurich, Switzerland; Neuroscience Center, University of Zurich, CH-8057 Zurich, Switzerland.
The Journal of comparative neurology.J Comp Neurol.2012 Dec 1;520(17):3895-911. doi: 10.1002/cne.23129.
In the spinal cord dorsal horn, presynaptic GABA(A) receptors (GABA(A) Rs) in the terminals of nociceptors as well as postsynaptic receptors in spinal neurons regulate the transmission of nociceptive and somatosensory signals from the periphery. GABA(A) Rs are heterogeneous and distinguished functi
PMID 22522945

Japanese Journal

Analgesic effect of Ilex paraguariensis extract on postoperative and neuropathic pain in rats

Lim Dong Wook,Kim Jae Goo,Han Taewon,Jung Sung Keun,Lim Eun Yeong,Han Daeseok,Kim Yun Tai
Biological and Pharmaceutical Bulletin advpub(0), 2015
… Neuropeptide Y (NPY) and pain-related cytokines were also determined in the dorsal root ganglia in a rat model of SNI. …
NAID 130005090664

Biodistribution of gold nanoparticles in mice and investigation of their possible translocation by nerve uptake around the alveolus

Koyama Yosuke,Matsui Yasuto,Shimada Yoko [他],Yoneda Minoru
The Journal of Toxicological Sciences 40(2), 243-249, 2015
… Furthermore, the possibility of migration of nanoparticles through the nerves that project around the alveolus, including the nodose ganglion and dorsal root ganglion (DRG), was investigated. … With respect to quantification in ganglia, the levels in most samples were lower than the limit of quantification of inductively coupled plasma mass spectrometry (ICP-MS). …
NAID 130004904038

Up-regulation of brain-derived neurotrophic factor in the dorsal root ganglion of the rat bone cancer pain model

Tomotsuka Naoto,Kaku Ryuji,Obata Norihiko,Matsuoka Yoshikazu,Kanzaki Hirotaka,Taniguchi Arata,Muto Noriko,Omiya Hiroki,Itano Yoshitaro,Sato Tadasu,Ichikawa Hiroyuki,Mizobuchi Satoshi,Morimatsu Hiroshi
Journal of Pain Research 7, 415-423, 2014-07-11
… in this study, we investigated changes of BDNF expression in dorsal root ganglia in a rat bone cancer pain model. … As we expected, BDNF mRNA (messenger ribonucleic acid) and protein were significantly increased in L3 dorsal root ganglia after intra-tibial inoculation of MRMT-1 rat breast cancer cells. …
NAID 120005517857

Related Pictures

★リンクテーブル★

リンク元	「背根神経節」「spinal ganglia」
関連記事	「root」「ganglia」「dorsal」

「背根神経節」

Posterior root ganglion
	A posterior root ganglion (DRG) from a chicken embryo (around stage of day 7) after incubation overnight in NGF growth medium stained with anti-neurofilament antibody. Axons growing out of the ganglion are visible.
	A spinal nerve with its anterior and posterior roots. The posterior root ganglion is the "spinal ganglion", following the posterior root.
Details
Latin	ganglion sensorium nervi spinalis
Precursor	neural crest
Identifiers
Gray's	p.750
MeSH	A08.340.390.340
Dorlands; /Elsevier	g_02/12384883
TA	A14.2.00.006
FMA	5888
	Anatomical terminology