Three functionally distinct classes of C-fibre nociceptors in primates

Matthew Wooten, Hao Jui Weng, Timothy V. Hartke, Jasenka Borzan, Amanda H. Klein, Brian Turnquist, Xinzhong Dong, Richard A. Meyer, Matthias Ringkamp

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60 Scopus citations

Abstract

In primates, C-fibre polymodal nociceptors are broadly classified into two groups based on mechanosensitivity. Here we demonstrate that mechanically sensitive polymodal nociceptors that respond either quickly (QC) or slowly (SC) to a heat stimulus differ in responses to a mild burn, heat sensitization, conductive properties and chemosensitivity. Superficially applied capsaicin and intradermal injection of Î 2-alanine, an MrgprD agonist, excite vigorously all QCs. Only 40% of SCs respond to β-alanine, and their response is only half that of QCs. Mechanically insensitive C-fibres (C-MIAs) are β-alanine insensitive but vigorously respond to capsaicin and histamine with distinct discharge patterns. Calcium imaging reveals that β-alanine and histamine activate distinct populations of capsaicin-responsive neurons in primate dorsal root ganglion. We suggest that histamine itch and capsaicin pain are peripherally encoded in C-MIAs, and that primate polymodal nociceptive afferents form three functionally distinct subpopulations with β-alanine responsive QC fibres likely corresponding to murine MrgprD-expressing, non-peptidergic nociceptive afferents.

Original languageEnglish (US)
Article number4122
JournalNature communications
Volume5
DOIs
StatePublished - Jun 20 2014

Bibliographical note

Funding Information:
This study was supported by NIH grant P01 NS47399 (M.R.), R01DE022750 and R01GM087369 (X.D.), the Blaustein Pain Research and Education Fund, the Brain Science Institute and the Neurosurgery Pain Research Institute at the Johns Hopkins University.

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