title: Expression of Vesicular Nucleotide Transporter in Rat Odontoblasts.
abstract: Several theories have been proposed regarding pain transmission mechanisms in tooth. However, the exact signaling mechanism from odontoblasts to pulp nerves remains to be clarified. Recently, ATP-associated pain transmission has been reported, but it is unclear whether ATP is involved in tooth pain transmission. In the present study, we focused on the vesicular nucleotide transporter (VNUT), a transporter of ATP into vesicles, and examined whether VNUT was involved in ATP release from odontoblasts. We examined the expression of VNUT in rat pulp by RT-PCR and immunostaining. ATP release from cultured odontoblast-like cells with heat stimulation was evaluated using ATP luciferase methods. VNUT was expressed in pulp tissue, and the distribution of VNUT-immunopositive vesicles was confirmed in odontoblasts. In odontoblasts, some VNUT-immunopositive vesicles were colocalized with membrane fusion proteins. Additionally P2X3, an ATP receptor, immunopositive axons were distributed between odontoblasts. The ATP release by thermal stimulation from odontoblast-like cells was inhibited by the addition of siRNA for VNUT. These findings suggest that cytosolic ATP is transported by VNUT and that the ATP in the vesicles is then released from odontoblasts to ATP receptors on axons. ATP vesicle transport in odontoblasts seems to be a key mechanism for signal transduction from odontoblasts to axons in the pulp.
authors.affiliation: Division of Orofacial Functions and Orthodontics, Kyushu Dental University.
authors.forename: Erina
authors.initials: E
authors.lastname: Ikeda
authors.affiliation: Department of Oral Anatomy and Cell Biology, Kagoshima University , 8-35-1, Sakuragaoka, Kagoshima 890-8544, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Goto
authors.affiliation: Division of Orofacial Functions and Orthodontics, Kyushu Dental University.
authors.forename: Kaori
authors.initials: K
authors.lastname: Gunjigake
authors.affiliation: Division of Orofacial Functions and Orthodontics, Kyushu Dental University.
authors.forename: Kayoko
authors.initials: K
authors.lastname: Kuroishi
authors.affiliation: Division of Orofacial Functions and Orthodontics, Kyushu Dental University.
authors.forename: Masae
authors.initials: M
authors.lastname: Ueda
authors.affiliation: Division of Anatomy, Kyushu Dental University.
authors.forename: Shinji
authors.initials: S
authors.lastname: Kataoka
authors.affiliation: Division of Anatomy, Kyushu Dental University.
authors.forename: Takashi
authors.initials: T
authors.lastname: Toyono
authors.affiliation: Division of Anatomy, Kyushu Dental University.
authors.forename: Mitsushiro
authors.initials: M
authors.lastname: Nakatomi
authors.affiliation: Division of Anatomy, Kyushu Dental University.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Seta
authors.affiliation: Division of Endodontics and Restorative Dentistry, Kyushu Dental University.
authors.forename: Chiaki
authors.initials: C
authors.lastname: Kitamura
authors.affiliation: Division of Infections and Molecular Biology, Kyushu Dental University , 2-6-1, Manazuru, Kokurakita-ku, Kitakyushu 803-8580, Japan.
authors.forename: Tatsuji
authors.initials: T
authors.lastname: Nishihara
authors.affiliation: Division of Orofacial Functions and Orthodontics, Kyushu Dental University.
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Kawamoto
keywords: ATP; VNUT; odontoblast; pain; pain transmission