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Titolo:
Tactile allodynia in the absence of C-fiber activation: altered firing properties of DRG neurons following spinal nerve injury
Autore:
Liu, CN; Wall, PD; Ben-Dor, E; Michaelis, M; Amir, R; Devor, M;
Indirizzi:
Hebrew Univ Jerusalem, Inst Life Sci, Dept Cell & Anim Biol, IL-91904 Jerusalem, Israel Hebrew Univ Jerusalem Jerusalem Israel IL-91904 -91904 Jerusalem, Israel Med Sch St Thomas, Dept Physiol, London, England Med Sch St Thomas London England Thomas, Dept Physiol, London, England Univ Kiel, Inst Physiol, D-24098 Kiel, Germany Univ Kiel Kiel Germany D-24098 Kiel, Inst Physiol, D-24098 Kiel, Germany
Titolo Testata:
PAIN
fascicolo: 3, volume: 85, anno: 2000,
pagine: 503 - 521
SICI:
0304-3959(200004)85:3<503:TAITAO>2.0.ZU;2-Z
Fonte:
ISI
Lingua:
ENG
Soggetto:
DORSAL-ROOT GANGLION; PRIMARY SENSORY NEURONS; INFLAMMATORY PAIN HYPERSENSITIVITY; NEUROPATHIC PAIN; PERIPHERAL-NERVE; RAT MODEL; ELECTROPHYSIOLOGICAL CHARACTERISTICS; THERMAL HYPERALGESIA; MEMBRANE-PROPERTIES; CROSS-EXCITATION;
Keywords:
axotomy; dorsal root ganglion; ectopic firing; neuropathic pain; pain;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Clinical Medicine
Life Sciences
Citazioni:
98
Recensione:
Indirizzi per estratti:
Indirizzo: Devor, M Hebrew Univ Jerusalem, Inst Life Sci, Dept Cell & Anim Biol, IL-91904 Jerusalem, Israel Hebrew Univ Jerusalem Jerusalem Israel IL-91904 rusalem, Israel
Citazione:
C.N. Liu et al., "Tactile allodynia in the absence of C-fiber activation: altered firing properties of DRG neurons following spinal nerve injury", PAIN, 85(3), 2000, pp. 503-521

Abstract

We examined the relation between ectopic afferent firing and tactile allodynia in the Chung model of neuropathic pain. Transection of the L5 spinal nerve in rats triggered a sharp, four- to six-fold increase in the spontaneous ectopic discharge recorded in vivo in sensory axons in the ipsilateral L5 dorsal root (DR). The increase, which was not yet apparent 16 h postoperatively, was complete by 24 h. This indicates rapid modification of the electrical properties of the neurons. Qnly A-neurons, primarily rapidly conducting A-neurons, contributed to the discharge. No spontaneously active C-neurons were encountered. Tactile allodynia in hindlimb skin emerged during precisely the same time window after spinal nerve section as the ectopia, suggesting that ectopic activity in injured myelinated afferents can trigger central sensitization, the mechanism believed to be responsible for tactile allodynia in the Chung model. Most of the spike activity originated in the somata of axotomized DRG neurons; the spinal nerve end neuroma accounted foronly a quarter of the overall ectopic barrage. Intracellular recordings from afferent neuron somata in excised DRGs in vitro revealed changes in excitability that closely paralleled those seen in the DR axon recordings in vivo. Corresponding changes in biophysical characteristics of the axotomized neurons were catalogued. Axotomy carried out at a distance from the DRG, inthe mid-portion of the sciatic nerve, also triggered increased afferent excitability. However, this increase occurred at a later time following axotomy, and the relative contribution of DRG neuronal somata, as opposed to neuroma endings, was smaller. Axotomy triggers a wide variety of changes in the neurochemistry and physiology of primary afferent neurons. Investigators studying DRG neurons in culture need to be alert to the rapidity with whichaxotomy, an inevitable consequence of DRG excision and dissociation, alters key properties of these neurons. Our identification of a specific population of neurons whose firing properties change suddenly and synchronously following axotomy, and whose activity is associated with tactile allodynia, provides a powerful vehicle for defining the specific cascade of cellular and molecular events that underlie neuropathic pain. (C) 2000 International Association for the Study of Pain. Published by Elsevier Science B.V. All rights reserved.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 09/07/20 alle ore 20:03:41