Selective excitation by capsaicin of mechano-heat sensitive nociceptors in rat skin

Janos Szolcsanyi, Fernand Anton, Peter W. Reeh, Hermann O. Handwerker

Research output: Contribution to journalArticle

187 Citations (Scopus)

Abstract

The effect of close-by arterial injections of capsaicin on single afferent fibers of the saphenous nerve was studied on 82 units from control rats and on 44 units from rats pretreated with capsaicin (total dose 200 mg/kg applied subcutaneously under anesthesia 3 days before the experiment). In control rats low doses of capsaicin selectively excited mechano-heat sensitive cutaneous nociceptors (polymodal C fiber nociceptors and MH-Aδ nociceptors). The median threshold dose for polymodal nociceptors was 0.1 μg. Repeated injections of capsaicin in near-threshold doses evoked reproducible effects without obvious signs of desensitization. In contrast Aδ high-threshold mechanoreceptors, hair follicle receptors, cold receptors and C fiber mechanoreceptors were not excited by capsaicin even at doses of 5 μg. These high doses activated, however, some SA-II mechanoreceptors after a time lag, probably due to increased tissue turgor induced by plasma extravasation. Systemic capsaicin pretreatment of adult rats resulted in a selective decrease in the proportion of polymodal nociceptors among the afferent C-units, and an increment in the threshold dose of capsaicin of the responding polymodal nociceptors. It is concluded that in the adult rat capsaicin exerts a selective stimulatory and blocking effect on cutaneous mechano-heat sensitive nociceptors conducting both in the C fiber and Aδ fiber range.

Original languageEnglish
Pages (from-to)262-268
Number of pages7
JournalBrain research
Volume446
Issue number2
DOIs
Publication statusPublished - Apr 19 1988

Keywords

  • Capsaicin
  • Cutaneous receptor
  • Desensitization of polymodal nociceptor
  • Nociceptor

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology

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