title: The distribution of transient receptor potential melastatin-8 in the rat soft palate, epiglottis, and pharynx.
abstract: Immunohistochemistry for transient receptor potential melastatin-8 (TRPM8), the cold and menthol receptor, was performed on the rat soft palate, epiglottis and pharynx. TRPM8-immunoreactive (IR) nerve fibers were located beneath the mucous epithelium, and occasionally penetrated the epithelium. These nerve fibers were abundant in the posterior portion of the soft palate and at the border region of naso-oral and laryngeal parts of the pharynx. The epiglottis was free from such nerve fibers. The double immunofluorescence method demonstrated that TRPM8-IR nerve fibers in the pharynx and soft palate were mostly devoid of calcitonin gene-related peptide-immunoreactivity (CGRP-IR). The retrograde tracing method also demonstrated that 30.1 and 8.7 % of sensory neurons in the jugular and petrosal ganglia innervating the pharynx contained TRPM8-IR, respectively. Among these neurons, the co-expression of TRPM8 and CGRP-IR was very rare. In the nodose ganglion, however, pharyngeal neurons were devoid of TRPM8-IR. Taste bud-like structures in the soft palate and pharynx contained 4-9 TRPM8-IR cells. In the epiglottis, the mucous epithelium on the laryngeal side had numerous TRPM8-IR cells. The present study suggests that TRPM8 can respond to cold stimulation when food and drinks pass through oral and pharyngeal cavities.
authors.affiliation: Division of Oral and Craniofacial Anatomy, Graduate School of Dentistry, Tohoku University, Sendai, Japan. tadasu@dent.tohoku.ac.jp
authors.forename: Tadasu
authors.initials: T
authors.lastname: Sato
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Fujita
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Kano
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hosokawa
authors.forename: Teruyoshi
authors.initials: T
authors.lastname: Kondo
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Suzuki
authors.forename: Eriko
authors.initials: E
authors.lastname: Kasahara
authors.forename: Noriaki
authors.initials: N
authors.lastname: Shoji
authors.forename: Takashi
authors.initials: T
authors.lastname: Sasano
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ichikawa
mesh_terms: D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism; D004825:Epiglottis / Q000166:cytology / Q000294:innervation / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D008297:Male; D010160:Palate, Soft / Q000166:cytology / Q000294:innervation / Q000378:metabolism*; D010614:Pharynx / Q000166:cytology / Q000294:innervation / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D050053:TRPM Cation Channels / Q000378:metabolism*
chemical_list: D050053:TRPM Cation Channels; C498947:Trpm8 protein, rat; D015740:Calcitonin Gene-Related Peptide