関: dorsal root ganglia、dorsal root ganglion、spinal ganglion

WordNet

work natural fibers into a thread; "spin silk"
prolong or extend; "spin out a visit" (同)spin out
the act of rotating rapidly; "he gave the crank a spin"; "it broke off after much twisting" (同)twirl, twist, twisting, whirl
a distinctive interpretation (especially as used by politicians to sway public opinion); "the campaign put a favorable spin on the story"
a short drive in a car; "he took the new car for a spin"
a swift whirling motion (usually of a missile)
revolve quickly and repeatedly around ones own axis; "The dervishes whirl around and around without getting dizzy" (同)spin around, whirl, reel, gyrate
form a web by making a thread; "spiders spin a fine web"
make up a story; "spin a yarn"
stream in jets, of liquids; "The creek spun its course through the woods"
twist and turn so as to give an intended interpretation; "The Presidents spokesmen had to spin the story to make it less embarrassing"
of or relating to the spine or spinal cord; "spinal cord"; "spinal injury"

PrepTutorEJDIC

(羊毛などから)〈糸など〉‘を'『紡ぐ』《+『名』+『out of』+『名』〈羊毛〉》,(糸などに)〈羊毛など〉‘を'紡ぐ《+『名』〈羊毛〉+『into』+『名』》 / 〈クモ・カイコなどが〉〈糸〉‘を'『吐く』;〈巣・繭〉‘を'かける / …‘を'くるくる回す / 〈物語など〉‘を'作る,話す / 『糸を紡ぐ』;〈クモ・カイコなどが〉糸を吐く / 〈こまなどが〉くるくる回る / 〈車などが〉疾走する / 〈頭などが〉くらくらする / 〈C〉〈U〉くるくる回すこと;回転 / 〈C〉《単数形で》(車などの)一走り / 〈C〉(飛行機の)きりもみ降下 / 〈C〉《単数形で》(価値などの)急落
背骨の / せき髄麻酔

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2012/12/14 14:28:46」(JST)

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In anatomy and neuroscience, a dorsal root ganglion (or spinal ganglion) is a nodule on a dorsal root of the spine that contains cell bodies of nerve cells (neurons) that carry signals from sensory organs toward the appropriate integration center. Nerves that carry signals toward the brain are known as afferent nerves.

Unique unipolar structure

The axons of dorsal 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 dorsal 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 dorsal horn of the 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 dorsal root ganglia lie along the vertebral column by the spine.

Embryology

The dorsal 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.

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 dorsal 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 dorsal 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 cytoskelton and cytoskeleton associated proteins.^[3] The presence of these channels in the dorsal root ganglion gives reason to believe that other sensory neurons may contain them as well.

High-Threshold Mechanosensitive Channels

HT channels have a possible role in nociception. These channels are found predominantly in smaller sensory neurons in the dorsal 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]

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. 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

Additional images

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

External links

SUNY Figs 02:04-09
BU Histology Learning System: 04401loa
Photo of model at Ohio State University
Diagram at webanatomy.net
Photo at uwlax.edu

UpToDate Contents

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English Journal

Inhibition of T-type calcium channels and hydrogen sulfide-forming enzyme reverses paclitaxel-evoked neuropathic hyperalgesia in rats.

Okubo K, Takahashi T, Sekiguchi F, Kanaoka D, Matsunami M, Ohkubo T, Yamazaki J, Fukushima N, Yoshida S, Kawabata A.SourceDivision of Pharmacology and Pathophysiology, Kinki University School of Pharmacy, 3-4-1 Kowakae, Higashi-Osaka 577-8502, Japan.
Neuroscience.Neuroscience.2011 Aug 11;188:148-56. Epub 2011 May 11.
Hydrogen sulfide (H(2)S), a gasotransmitter, facilitates pain sensation by targeting Ca(v)3.2 T-type calcium channels. The H(2)S/Ca(v)3.2 pathway appears to play a role in the maintenance of surgically evoked neuropathic pain. Given evidence that chemotherapy-induced neuropathic pain is blocked by e
PMID 21596106

Blockade of adrenomedullin receptors reverses morphine tolerance and its neurochemical mechanisms.

Wang D, Chen P, Li Q, Quirion R, Hong Y.SourceProvincial Key Laboratory of Developmental Biology and Neuroscience, College of Life Sciences, Fujian Normal University, Fuzhou, Fujian 350108, People's Republic of China.
Behavioural brain research.Behav Brain Res.2011 Aug 1;221(1):83-90. Epub 2011 Mar 4.
Adrenomedullin (AM) has been demonstrated to be involved in the development of opioid tolerance. The present study further investigated the role of AM in the maintenance of morphine tolerance, morphine-associated hyperalgesia and its cellular mechanisms. Intrathecal (i.t.) injection of morphine for
PMID 21382419

Japanese Journal

Identification of an evolutionarily conserved, functional noncoding element regulated by Six1 homeoprotein

Jeong Yongsu,Oh Sangtaek
Genes & Genetic Systems 85(3), 233-240, 2010
… Six1 is expressed in various tissues including the nervous system during ontogenesis and has been implicated in cell differentiation, morphogenesis, and organogenesis of the ganglia and sensory placodes. … One of the novel sequences, which was designated Six1-bound Regulatory Element 1 (SRE1), was sufficient to activate lacZ reporter expression in the cranial and spinal ganglia. …
NAID 130000413751

脳機能イメージングによるヒト二足歩行の中枢神経制御機構の解明

花川隆
Equilibrium research 68(3), 176-182, 2009-06-01
… Neurophysiological studies on quadruped animals have indicated the importance of the basal ganglia-brainstem system for the neural control of gait. … However, recent advances in neuroimaging techniques have also begun to shed light on the role of the cortical motor areas, which project to the brainstem, the spinal cord and the basal ganglia, in the control of bipedal gait in primates. …
NAID 10026088310

Related Pictures

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関連記事	「spinal」「ganglia」「spin」

「spinal」

Dorsal root ganglion
	This is a dorsal 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 dorsal root ganglion is the "spinal ganglion", following the posterior/dorsal root.
Latin	ganglion sensorium nervi spinalis
Gray's	subject #185 750
Precursor	neural crest
MeSH	Spinal+Ganglia
Code	TA A14.2.00.006