A reliable method for the preferential activation of C- or A-fibre heat nociceptors

Simon McMullan*, Daniel A.A. Simpson, Bridget M. Lumb

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

42 Citations (Scopus)

Abstract

There is strong evidence that A- and C-fibre nociceptors evoke significantly different sensory experiences, are differentially sensitive to pharmacological intervention, and play different roles in pain pathology. It is therefore of considerable interest to be able to selectively activate one fibre type or the other in studies of nociceptive processing. Here, we report significant modifications to a non-invasive technique, first described by Yeomans et al. [Pain 59 (1994) 85; Pain 68 (1996) 141; Pain 68 (1996) 133], which uses different rates of skin heating to preferentially activate A- or C-nociceptors. A copper disk (diameter: 4 mm) was used to transfer heat evenly across the dorsal surface of the rat hindpaw. Initial experiments established the relationship between the temperature at the skin surface and the sub-epidermal temperature. Subsequently, the vanilloid capsaicin, which sensitises unmyelinated C-mechanoheat nociceptors, was shown to decrease the thresholds of reflex responses evoked by slow rates of heating. In contrast thresholds of responses to fast rates of skin heating were unchanged, indicating that nociceptors activated by this stimulus were capsaicin-insensitive A-fibre heat nociceptors.

Original languageEnglish
Pages (from-to)133-139
Number of pages7
JournalJournal of Neuroscience Methods
Volume138
Issue number1-2
DOIs
Publication statusPublished - 30 Sep 2004
Externally publishedYes

Keywords

  • C-fibre
  • Capsaicin
  • EMG
  • Heat
  • Method
  • Nociception
  • Rat
  • Reflex

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