title: External Dentin Stimulation Induces ATP Release in Human Teeth.
abstract: ATP is involved in neurosensory processing, including nociceptive transduction. Thus, ATP signaling may participate in dentin hypersensitivity and dental pain. In this study, we investigated whether pannexins, which can form mechanosensitive ATP-permeable channels, are present in human dental pulp. We also assessed the existence and functional activity of ecto-ATPase for extracellular ATP degradation. We further tested if ATP is released from dental pulp upon dentin mechanical or thermal stimulation that induces dentin hypersensitivity and dental pain and if pannexin or pannexin/gap junction channel blockers reduce stimulation-dependent ATP release. Using immunofluorescence staining, we demonstrated immunoreactivity of pannexin 1 and 2 in odontoblasts and their processes extending into the dentin tubules. Using enzymatic histochemistry staining, we also demonstrated functional ecto-ATPase activity within the odontoblast layer, subodontoblast layer, dental pulp nerve bundles, and blood vessels. Using an ATP bioluminescence assay, we found that mechanical or cold stimulation to the exposed dentin induced ATP release in an in vitro human tooth perfusion model. We further demonstrated that blocking pannexin/gap junction channels with probenecid or carbenoxolone significantly reduced external dentin stimulation-induced ATP release. Our results provide evidence for the existence of functional machinery required for ATP release and degradation in human dental pulp and that pannexin channels are involved in external dentin stimulation-induced ATP release. These findings support a plausible role for ATP signaling in dentin hypersensitivity and dental pain.
authors.affiliation: Division of General Dentistry, Eastman Institute for Oral Health, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA xiuxin_liu@urmc.rochester.edu.
authors.forename: X
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Neurosurgery, Qilu Hospital, Shandong University, Jinan, China.
authors.forename: C
authors.initials: C
authors.lastname: Wang
authors.affiliation: Center for Translational Neuromedicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA.
authors.forename: T
authors.initials: T
authors.lastname: Fujita
authors.affiliation: Division of General Dentistry, Eastman Institute for Oral Health, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA.
authors.forename: H S
authors.initials: HS
authors.lastname: Malmstrom
authors.affiliation: Center for Translational Neuromedicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA.
authors.forename: M
authors.initials: M
authors.lastname: Nedergaard
authors.affiliation: Division of General Dentistry, Eastman Institute for Oral Health, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA.
authors.forename: Y F
authors.initials: YF
authors.lastname: Ren
authors.affiliation: Department of Pharmacology and Physiology, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA.
authors.forename: R T
authors.initials: RT
authors.lastname: Dirksen
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D003782:Dental Pulp / Q000378:metabolism; D003804:Dentin / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D006801:Humans; D014070:Tooth / Q000378:metabolism*
chemical_list: D000255:Adenosine Triphosphate
keywords: NTPDases; dental pulp; dentin sensitivity; odontoblasts; pain; pannexins