title: Assessment of intraoral mucosal pain induced by the application of capsaicin.
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).
  
  
  METHODS
  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.
authors.affiliation: 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.
authors.forename: Ryuji
authors.initials: R
authors.lastname: Terayama
authors.affiliation: 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.
authors.forename: Kotaro
authors.initials: K
authors.lastname: Maruhama
authors.affiliation: 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.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Tsuchiya
authors.affiliation: 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.
authors.forename: Masahide
authors.initials: M
authors.lastname: Mizutani
authors.affiliation: 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.
authors.forename: Seiji
authors.initials: S
authors.lastname: Iida
authors.affiliation: 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.
authors.forename: Tomosada
authors.initials: T
authors.lastname: Sugimoto
mesh_terms: D000818:Animals; D002211:Capsaicin / Q000494:pharmacology*; D004195:Disease Models, Animal; D006930:Hyperalgesia / Q000503:physiopathology*; D008297:Male; D009619:Nociceptors / Q000187:drug effects*; D010147:Pain Measurement; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D061221:Trigeminal Nerve Injuries / Q000188:drug therapy*
chemical_list: D016760:Proto-Oncogene Proteins c-fos; D002211:Capsaicin
keywords: Behaviour; Capsaicin; Immunohistochemistry; Medullary dorsal horn; Nerve injury; c-Fos