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L5 spinal nerve axotomy induces sensitization of cutaneous L4 Aβ-nociceptive dorsal root ganglion neurons in the rat in vivo.
Neurosci Lett. 2016 06 15; 624:72-7.NL

Abstract

Partial nerve injury often leads to peripheral neuropathic pain (PNP), a major health problem that lacks effective drug treatment. PNP is characterized by ongoing/spontaneous pain, and hypersensitivity to noxious (hyperalgesia) and innocuous (allodynia) stimuli. Preclinical studies using the L5 spinal nerve ligation/axotomy (SNL/SNA) model of PNP suggest that this type of chronic pain results partly from sensitization of ipsilateral L4C-and Aδ-fiber nociceptive dorsal root ganglion (DRG) neurons, but whether L4 β-nociceptors, which constitute a substantial group of DRG neurons, also become sensitized remains unanswered. To address this issue, intracellular recordings from somata of cutaneous Aβ-nociceptors (classified according to their dorsal root conduction velocities (>6.5m/s), and physiologically based on their responses to noxious (but not innocuous) mechanical stimuli) were made from L4-DRGs in normal (control) rats and in rats seven days after L5 SNA in vivo. Compared with control, cutaneous L4 Aβ-nociceptive DRG neurons in SNA rats (that developed mechanical hypersensitivity) exhibited sensitization indicated by: a) decreased mean mechanical threshold (from 57.8±7.1 to 10.3±1.7mN), b) decreased mean dorsal root electrical threshold (from 11.4±0.7 to 4.3±0.4V), c) increased mean response to a suprathreshold mechanical stimulus (from 18.5±1.8 to 34±3.7spikes/sec) and d) an obvious, but non-significant, increase in the incidence of ongoing/spontaneous activity (from 3% to 18%). These findings suggest that cutaneous L4 Aβ-nociceptors also become sensitized after L5 SNA, and that sensitization of this subclass of A-fiber nociceptors may contribute both directly and indirectly to nerve injury-induced PNP.

Authors+Show Affiliations

Department of Physiology, College of Medicine, King Saud University, P.O. Box 7805, Riyadh 11472, KSA. Electronic address: ldjouhri@ksu.edu.sa.

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

27173166

Citation

Djouhri, Laiche. "L5 Spinal Nerve Axotomy Induces Sensitization of Cutaneous L4 Aβ-nociceptive Dorsal Root Ganglion Neurons in the Rat in Vivo." Neuroscience Letters, vol. 624, 2016, pp. 72-7.
Djouhri L. L5 spinal nerve axotomy induces sensitization of cutaneous L4 Aβ-nociceptive dorsal root ganglion neurons in the rat in vivo. Neurosci Lett. 2016;624:72-7.
Djouhri, L. (2016). L5 spinal nerve axotomy induces sensitization of cutaneous L4 Aβ-nociceptive dorsal root ganglion neurons in the rat in vivo. Neuroscience Letters, 624, 72-7. https://doi.org/10.1016/j.neulet.2016.05.008
Djouhri L. L5 Spinal Nerve Axotomy Induces Sensitization of Cutaneous L4 Aβ-nociceptive Dorsal Root Ganglion Neurons in the Rat in Vivo. Neurosci Lett. 2016 06 15;624:72-7. PubMed PMID: 27173166.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - L5 spinal nerve axotomy induces sensitization of cutaneous L4 Aβ-nociceptive dorsal root ganglion neurons in the rat in vivo. A1 - Djouhri,Laiche, Y1 - 2016/05/09/ PY - 2016/04/19/received PY - 2016/05/06/revised PY - 2016/05/07/accepted PY - 2016/5/14/entrez PY - 2016/5/14/pubmed PY - 2017/6/7/medline KW - Myelinated nerve fibers KW - Neuropathic pai KW - Nociceptors KW - Primary sensory neurons KW - Uninjured neurons SP - 72 EP - 7 JF - Neuroscience letters JO - Neurosci Lett VL - 624 N2 - Partial nerve injury often leads to peripheral neuropathic pain (PNP), a major health problem that lacks effective drug treatment. PNP is characterized by ongoing/spontaneous pain, and hypersensitivity to noxious (hyperalgesia) and innocuous (allodynia) stimuli. Preclinical studies using the L5 spinal nerve ligation/axotomy (SNL/SNA) model of PNP suggest that this type of chronic pain results partly from sensitization of ipsilateral L4C-and Aδ-fiber nociceptive dorsal root ganglion (DRG) neurons, but whether L4 β-nociceptors, which constitute a substantial group of DRG neurons, also become sensitized remains unanswered. To address this issue, intracellular recordings from somata of cutaneous Aβ-nociceptors (classified according to their dorsal root conduction velocities (>6.5m/s), and physiologically based on their responses to noxious (but not innocuous) mechanical stimuli) were made from L4-DRGs in normal (control) rats and in rats seven days after L5 SNA in vivo. Compared with control, cutaneous L4 Aβ-nociceptive DRG neurons in SNA rats (that developed mechanical hypersensitivity) exhibited sensitization indicated by: a) decreased mean mechanical threshold (from 57.8±7.1 to 10.3±1.7mN), b) decreased mean dorsal root electrical threshold (from 11.4±0.7 to 4.3±0.4V), c) increased mean response to a suprathreshold mechanical stimulus (from 18.5±1.8 to 34±3.7spikes/sec) and d) an obvious, but non-significant, increase in the incidence of ongoing/spontaneous activity (from 3% to 18%). These findings suggest that cutaneous L4 Aβ-nociceptors also become sensitized after L5 SNA, and that sensitization of this subclass of A-fiber nociceptors may contribute both directly and indirectly to nerve injury-induced PNP. SN - 1872-7972 UR - https://www.unboundmedicine.com/medline/citation/27173166/L5_spinal_nerve_axotomy_induces_sensitization_of_cutaneous_L4_Aβ_nociceptive_dorsal_root_ganglion_neurons_in_the_rat_in_vivo_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0304-3940(16)30307-X DB - PRIME DP - Unbound Medicine ER -