title: Expression of transient receptor potential vanilloid 1 and anoctamin 1 in rat trigeminal ganglion neurons innervating the tongue.
abstract: Transient receptor potential vanilloid 1 (TRPV1) is a polymodal sensor that is activated by heat (>43 °C), acid, or capsaicin, the pungent ingredient of hot peppers. Reports that mice lacking TRPV1 display heat avoidance behaviors and TRPV1-negative neurons respond to heat suggest that an additional heat sensor is present. Anoctamin 1 (ANO1; also known as transmembrane protein 16A [TMEM16A]), is a component of Ca(2+)-activated chloride channels (CaCCs), and has been recently identified as a heat sensor, activated by temperatures over 44 °C. ANO1 is highly co-localized with TRPV1 in small-diameter dorsal root ganglion (DRG) neurons. The aim of the present study was to investigate co-expression of ANO1 and TRPV1 in rat trigeminal ganglion (TG) neurons innervating the tongue by using retrograde labeling and immunohistochemical techniques. Fluoro-gold (FG) retrograde labeling was used to identify the TG neurons innervating the anterior two thirds of the tongue; as expected, most labeling was detected in the mandibular division of the TGs. The FG-labeled TG neurons showed TRPV1 immunoreactivity (17.9%) and ANO1 immunoreactivity (13.7%), indicating that TRPV1- and ANO1-expressing neurons were present in the mandibular division of the TGs. Seventy-six percent of the ANO1-immunoreactive TG neurons were also immunoreactive for TRPV1; this co-expression was mainly detected in small- to medium-diameter TG neurons. The high degree of co-expression of TRPV1 and ANO1 suggests that cooperation between ANO1 and TRPV1 plays a role in the signaling pathways of nociceptive TG neurons.
authors.affiliation: Department of Physiology, School of Life Dentistry at Tokyo, Nippon Dental University, 1-9-20, Fujimi-cho, Chiyoda-ku, Tokyo 102-8159, Japan. Electronic address: kanazawa@tky.ndu.ac.jp.
authors.forename: Takuya
authors.initials: T
authors.lastname: Kanazawa
authors.affiliation: Department of Physiology, School of Life Dentistry at Tokyo, Nippon Dental University, 1-9-20, Fujimi-cho, Chiyoda-ku, Tokyo 102-8159, Japan.
authors.forename: Shigeji
authors.initials: S
authors.lastname: Matsumoto
mesh_terms: D000818:Animals; D000075369:Anoctamin-1; D018118:Chloride Channels / Q000378:metabolism*; D005260:Female; D008297:Male; D009474:Neurons / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D050916:TRPV Cation Channels / Q000378:metabolism*; D014059:Tongue / Q000294:innervation*; D012668:Trigeminal Ganglion / Q000166:cytology / Q000378:metabolism*
chemical_list: C552942:ANO1 protein, rat; D000075369:Anoctamin-1; D018118:Chloride Channels; D050916:TRPV Cation Channels; C493922:Trpv1 protein, rat
keywords: ANO1; Nociception; TMEM16A; TRPV1; Tongue; Trigeminal ganglion