Assessment of intraoral mucosal pain induced by the application of capsaicin

Ryuji Terayama; Kotaro Maruhama; Hiroki Tsuchiya; Masahide Mizutani; Seiji Iida; Tomosada Sugimoto

doi:10.1016/j.archoralbio.2014.08.008

Assessment of intraoral mucosal pain induced by the application of capsaicin

Arch Oral Biol. 2014 Dec;59(12):1334-41. doi: 10.1016/j.archoralbio.2014.08.008. Epub 2014 Aug 23.

Authors

Ryuji Terayama¹, Kotaro Maruhama², Hiroki Tsuchiya³, Masahide Mizutani⁴, Seiji Iida⁴, Tomosada Sugimoto²

Affiliations

¹ Department of Oral Function and Anatomy, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8525, Japan; Advanced Research Center for Oral and Craniofacial Sciences, Okayama University Dental School, Okayama 700-8525, Japan. Electronic address: ryujit@md.okayama-u.ac.jp.
² Department of Oral Function and Anatomy, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8525, Japan; Advanced Research Center for Oral and Craniofacial Sciences, Okayama University Dental School, Okayama 700-8525, Japan.
³ Department of Oral Function and Anatomy, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8525, Japan; ASAHI Medical College at Okayama, Okayama 700-0028, Japan.
⁴ Department of Oral and Maxillofacial Reconstructive Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8525, Japan; Advanced Research Center for Oral and Craniofacial Sciences, Okayama University Dental School, Okayama 700-8525, Japan.

PMID: 25189505
DOI: 10.1016/j.archoralbio.2014.08.008

Abstract

Objective: To develop an objective method for assessing nociceptive behaviour in an animal model of capsaicin-induced intraoral pain. Changes in nociceptive responses were also examined after injury to the inferior alveolar nerve (IAN).

Design: Nociceptive responses evoked by the intraoral application of various doses of capsaicin were analyzed in lightly anaesthetized rats. The number of c-Fos protein-like immunoreactive (Fos-LI) neurons in the medullary dorsal horn (MDH) induced by the intraoral application of capsaicin was measured. Behavioural and c-Fos responses were also examined 14 days after injury to the IAN.

Results: Larger doses of intraoral capsaicin (1, 10 and 100μg) induced vigorous licking behaviour and c-Fos response in the MDH in a reproducible manner. The magnitudes of both behavioural activity and the c-Fos response from the 10 and 100μg doses of capsaicin were significantly greater than that by the 1μg dose. Injury to the IAN exaggerated the behavioural and c-Fos responses evoked by intraoral capsaicin.

Conclusions: The intraoral application of capsaicin is a valid and reliable method for studying intraoral pain and hyperalgesia following nerve injury.

Keywords: Behaviour; Capsaicin; Immunohistochemistry; Medullary dorsal horn; Nerve injury; c-Fos.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Capsaicin / pharmacology*
Disease Models, Animal
Hyperalgesia / physiopathology*
Male
Nociceptors / drug effects*
Pain Measurement
Proto-Oncogene Proteins c-fos / metabolism
Rats
Rats, Sprague-Dawley
Trigeminal Nerve Injuries / drug therapy*

Substances

Proto-Oncogene Proteins c-fos
Capsaicin