Intradermal injection of capsaicin induces acute substance P release from rat spinal cord dorsal horn

Jing Yin Yan, Rui Qing Sun, Michael G. Hughes, David J. McAdoo, William D. Willis

Research output: Contribution to journalArticlepeer-review


Increased release of substance P (SP) from the dorsal horn following noxious stimuli, such as spinal administration of capsaicin, has been demonstrated in previous studies. However, changes in the release of SP in response to intradermal injection of capsaicin still remain unknown. This study was designed to demonstrate in vivo spinal SP release following intradermal injection of capsaicin (3%, 50 μl), using polyimide tubing with a single hole introduced into the rat dorsal horn. The changes in the content of SP in the rat dorsal horn tissues before and after capsaicin (3%, 50 μl) injection were also investigated. The SP concentration in the samples was analyzed using an enzyme-linked immunosorbent assay (ELISA). We found that intradermal injection of capsaicin induced a quick SP release within the dorsal horn. The peak of the release appeared around 10 min after the injection. In contrast, intradermal injection of capsaicin had no significant effect on the SP content in the dorsal horn. This study has provided direct evidence of the effect of intradermal injection of capsaicin on SP release within the dorsal horn, with the major source being from the central terminals of primary afferents.

Original languageEnglish (US)
Pages (from-to)183-186
Number of pages4
JournalNeuroscience Letters
Issue number3
StatePublished - Dec 27 2006
Externally publishedYes


  • Capsaicin
  • Substance P

ASJC Scopus subject areas

  • General Neuroscience


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