TRPA1 contributes to capsaicin‐induced facial cold hyperalgesia in rats. (5th November 2014)

• Record Type: Journal Article
• Authors: Honda, Kuniya; Shinoda, Masamichi; Furukawa, Akihiko; Kita, Kozue; Noma, Noboru; Iwata, Koichi
• Is Part Of: European journal of oral sciences. Volume 122:Number 6(2014:Dec.)
• Page Start: 391
• Page End: 396
• Publication Date: 2014-11-05
• Subjects: Dentistry -- Periodicals; Oral medicine -- Periodicals; 617.6005
• DOI: 10.1111/eos.12157
• Languages: English
• ISSNs: 0909-8836

Abstract

<abstract abstract-type="main" id="eos12157-abs-0001"> <title> <x xml:space="preserve">Abstract</x> </title> <p>Orofacial cold hyperalgesia is known to cause severe persistent pain in the face following trigeminal nerve injury or inflammation, and transient receptor potential (TRP) vanilloid 1 (TRPV1) and TRP ankylin 1 (TRPA1) are thought to be involved in cold hyperalgesia. However, how these two receptors are involved in cold hyperalgesia is not fully understood. To clarify the mechanisms underlying facial cold hyperalgesia, nocifensive behaviors to cold stimulation, the expression of TRPV1 and TRPA1 in trigeminal ganglion (TG) neurons, and TG neuronal excitability to cold stimulation following facial capsaicin injection were examined in rats. The head‐withdrawal reflex threshold (HWRT) to cold stimulation of the lateral facial skin was significantly decreased following facial capsaicin injection. This reduction of HWRT was significantly recovered following local injection of TRPV1 antagonist as well as TRPA1 antagonist. Approximately 30% of TG neurons innervating the lateral facial skin expressed both TRPV1 and TRPA1, and about 64% of TRPA1‐positive neurons also expressed TRPV1. The TG neuronal excitability to noxious cold stimulation was significantly increased following facial capsaicin injection and this increase was recovered by pretreatment with TRPA1 antagonist. These findings suggest that TRPA1 sensitization via TRPV1 signaling in TG neurons is involved in cold hyperalgesia following facial skin capsaicin injection.</p> </abstract>