title: Topical capsaicin application causes cold hypersensitivity in awake monkeys.
abstract: Recent animal studies have demonstrated that many trigeminal ganglion neurons co-express TRPV1 and TRPA1 receptors following peripheral inflammation. In the present study, we examined whether cold receptors were sensitized by capsaicin in awake monkeys. Two monkeys were trained to detect a change in cold stimulus temperature (30 degrees C to 0.5, 1.0, 1.5 or 2.0 degrees C) applied to the facial skin. A total of 589 trials were studied, and the number of escape and hold-through trials and detection latency were measured. The number of escape trials was increased after capsaicin treatment, whereas that of hold-through trials was decreased. Detection latency was significantly decreased after capsaicin treatment. The present findings suggest that topical application of capsaicin to the facial skin induces reversible hypersensitivity to a facial cold stimulus in behaving monkeys.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Nihon University School of Dentistry, Tokyo, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kamo
authors.forename: Kuniya
authors.initials: K
authors.lastname: Honda
authors.forename: Junichi
authors.initials: J
authors.lastname: Kitagawa
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Tsuboi
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kondo
authors.forename: Masato
authors.initials: M
authors.lastname: Taira
authors.forename: Akiko
authors.initials: A
authors.lastname: Yamashita
authors.forename: Narumi
authors.initials: N
authors.lastname: Katsuyama
authors.forename: Yuji
authors.initials: Y
authors.lastname: Masuda
authors.forename: Takafumi
authors.initials: T
authors.lastname: Kato
authors.forename: Koichi
authors.initials: K
authors.lastname: Iwata
mesh_terms: D000279:Administration, Cutaneous; D000818:Animals; D002211:Capsaicin / Q000008:administration & dosage / Q000494:pharmacology*; D003080:Cold Temperature; D005145:Face / Q000294:innervation; D008251:Macaca; D011930:Reaction Time / Q000187:drug effects; D018689:Sensory System Agents / Q000008:administration & dosage / Q000494:pharmacology*; D012684:Sensory Thresholds / Q000187:drug effects*; D012867:Skin / Q000187:drug effects / Q000294:innervation; D050916:TRPV Cation Channels / Q000187:drug effects; D013823:Thermoreceptors / Q000187:drug effects*; D014851:Wakefulness
chemical_list: D018689:Sensory System Agents; D050916:TRPV Cation Channels; D002211:Capsaicin