Capsaicin-sensitive cutaneous primary afferents convey electrically induced itch in humans

NEUROSCIENCE LETTERS

卷:666

Article

Andersen, Hjalte H.¹  van Laarhoven, Antoinette I. M.^1,2,3,4  Justesen, Frederik D.¹  Pedersen, Jacob B.¹  Sorensen, Laurits L.¹  Jensen, Line P.¹  Arendt-Nielsen, Lars¹ 

[1] Aalborg Univ, Fac Med, Dept Hlth Sci & Technol, Lab Expt Cutaneous Pain Res,SMI, Aalborg, Denmark

[2] Leiden Univ, Fac Social & Behav Sci, Hlth Med & Neuropsychol Unit, Leiden, Netherlands

[3] Leiden Univ, LIBC, Leiden, Netherlands

[4] Leiden Univ, Med Ctr, Dept Psychiat, Leiden, Netherlands

关键词: Itch;    C-Fibers;    TPRV1;    Histamine;    Capsaicin;    Pruriceptors;    Nociceptors;   

DOI  :  10.1016/j.neulet.2017.11.061

来源: Elsevier

【 摘 要 】

Specially designed transcutaneous electrical stimulation paradigms can be used to provoke experimental itch. However, it is unclear which primary afferent fibers are activated and whether they represent pathophysiologically relevant, C-fiber mediated itch. Since low-threshold mechano-receptors have recently been implicated in pruriception we aimed to characterize the peripheral primary afferent subpopulation conveying electrically evoked itch in humans (50 Hz stimulation, 100 mu s square pulses, stimulus-response function to graded stimulus intensity). In 10 healthy male volunteers a placebo-controlled, 24-h 8% topical capsaicin-induced defunctionalization of capsaicin-sensitive (transient receptor potential V1-positive, 'TRPV1'+) cutaneous fibers was performed. Histaminergic itch (1% solution introduced by a prick test lancet) was provoked as a positive control condition. Capsaicin pretreatment induced profound loss of warmth and heat pain sensitivity (pain threshold and supra-threshold ratings) as assessed by quantitative sensory testing, indicative of efficient TRPV1-fiber defunctionalization (all outcomes: P < 0.0001). The topical capsaicin robustly, and with similar efficaciousness, inhibited itch intensity evoked by electrical stimulation and histamine (-89 +/- 4.1% and -78 +/- 4.9%, respectively, both: P < 0.0001 compared to the placebo patch area). The predominant primary afferent substrate for electrically evoked itch in humans, using the presently applied stimulation paradigm, is concluded to be capsaicin-sensitive polymodal C-fibers.

【 授权许可】

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