title: Detection of acid-sensing ion channel 3 (ASIC3) in periodontal Ruffini endings of mouse incisors.
abstract: The acid-sensing ion channel 3 (ASIC3), a member of the epithelial sodium channel/degenerin (ENaC/DEG) superfamily, has been reported to participate in acid sensing, mechanosensation, and nociception. However, no information is available regarding the precise localization and function of this molecule in the periodontal ligament, which contains abundant sensory nerves originating from the trigeminal ganglion. The present study examined the expression of ASIC3 in the lingual periodontal ligament of mouse incisors by immunohistochemistry. Furthermore, the expression of ASIC3 in the trigeminal ganglion - which innervates the periodontal ligament - was investigated at protein (immunohistochemistry and quantitative analysis) and mRNA levels (RT-PCR technique and in situ hybridization histochemistry). Immunohistochemistry for ASIC3 was able to demonstrate dendritic profiles of the periodontal Ruffini endings in the mouse incisors. No thin fibers terminating as nociceptive free nerve endings exhibited ASIC3 immunoreactivity. Double immunofluorescent staining revealed ASIC3 immunoreaction in the axoplasm but not in the ordinary Schwann cells - including the associated terminal Schwann cells. Observation of the trigeminal ganglia showed variously sized neurons expressing ASIC3 immunoreaction; the most intense immunopositivity was found in the small and medium-sized neurons, as confirmed by in situ hybridization histochemistry using a specific cRNA probe. Quantitative analysis on trigeminal ganglion neurons showed that 38.0% of ASIC3 neurons could be categorized as medium-sized neurons which mediate mechanotransduction. These findings suggest that ASIC3 functions as a molecule for mechanosensation in the periodontal Ruffini endings.
authors.affiliation: Division of Oral Anatomy, Niigata University Graduate School of Medical and Dental Sciences, 2-5274 Gakkocho-dori, Chuo-ku, Niigata 951-8514, Japan.
authors.forename: Farhana
authors.initials: F
authors.lastname: Rahman
authors.forename: Fumiko
authors.initials: F
authors.lastname: Harada
authors.forename: Isao
authors.initials: I
authors.lastname: Saito
authors.forename: Akiko
authors.initials: A
authors.lastname: Suzuki
authors.forename: Yoshiro
authors.initials: Y
authors.lastname: Kawano
authors.forename: Kenji
authors.initials: K
authors.lastname: Izumi
authors.forename: Kayoko
authors.initials: K
authors.lastname: Nozawa-Inoue
authors.forename: Takeyasu
authors.initials: T
authors.lastname: Maeda
mesh_terms: D062565:Acid Sensing Ion Channels; D000818:Animals; D005455:Fluorescent Antibody Technique; D007150:Immunohistochemistry; D007180:Incisor / Q000294:innervation* / Q000378:metabolism; D008297:Male; D008465:Mechanoreceptors / Q000378:metabolism*; D051379:Mice; D008813:Mice, Inbred ICR; D010513:Periodontal Ligament / Q000294:innervation / Q000378:metabolism; D010519:Periodontium / Q000294:innervation / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015222:Sodium Channels / Q000096:biosynthesis*; D012668:Trigeminal Ganglion / Q000378:metabolism
chemical_list: C508378:ASIC3 protein, mouse; D062565:Acid Sensing Ion Channels; D015222:Sodium Channels