title: Sequential expression of endothelial nitric oxide synthase, inducible nitric oxide synthase, and nitrotyrosine in odontoblasts and pulp cells during dentin repair after tooth preparation in rat molars.
abstract: Nitric oxide (NO) stimulates osteoblast differentiation, but whether NO contributes to odontoblast differentiation during dentin repair is unknown. By using reverse transcription/polymerase chain reaction and immunostaining, we investigated the gene expression and/or immunolocalization of endothelial NO synthase (eNOS), inducible NOS (iNOS), and nitrotyrosine (a biomarker for NO-derived peroxinitrite), and alkaline phosphatase (ALP) and osteocalcin (early and terminal differentiation markers of odontoblasts, respectively) in dental pulp tissue after rat tooth preparation. At the early stage (1-3 days) post-preparation, markedly increased expression of iNOS and nitrotyrosine was found in odontoblasts and pulp cells beneath the cavity, whereas eNOS expression was significantly decreased. ALP mRNA expression was significantly increased after 1 day but decreased after 3 days, whereas ALP activity was weak in the dentin-pulp interface under the cavity after 1 day but strong after 3 days. Osteocalcin mRNA expression was significantly increased at this stage. At 7 days post-preparation, tertiary dentin was formed under the cavity. All the molecules studied were expressed at control levels in odontoblasts/pulp cells beneath the cavity. These findings show that abundant NO is released from odontoblasts and pulp cells at an early stage after tooth preparation and indicate that, after tooth preparation, the up-regulation of iNOS and nitrotyrosine in odontoblasts is synchronized with increased cellular expression of ALP and osteocalcin. Therefore, the NO synthesized by iNOS after tooth preparation probably participates in regulating odontoblast differentiation during tertiary dentinogenesis.
authors.affiliation: Department of Oral Anatomy and Cell Biology, Kyushu University Graduate School of Dental Science, Fukuoka, 812-8582, Japan.
authors.forename: Yu Feng
authors.initials: YF
authors.lastname: Mei
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Yamaza
authors.forename: Ikiru
authors.initials: I
authors.lastname: Atsuta
authors.forename: Atsushi
authors.initials: A
authors.lastname: Danjo
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Yamashita
authors.forename: Mizuho A
authors.initials: MA
authors.lastname: Kido
authors.forename: Masaaki
authors.initials: M
authors.lastname: Goto
authors.forename: Akifumi
authors.initials: A
authors.lastname: Akamine
authors.forename: Teruo
authors.initials: T
authors.lastname: Tanaka
mesh_terms: D000469:Alkaline Phosphatase / Q000235:genetics / Q000378:metabolism; D000818:Animals; D003782:Dental Pulp / Q000166:cytology / Q000201:enzymology*; D003804:Dentin / Q000166:cytology; D015971:Gene Expression Regulation, Enzymologic; D008297:Male; D008963:Molar / Q000201:enzymology*; D052247:Nitric Oxide Synthase Type II / Q000235:genetics* / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000235:genetics* / Q000378:metabolism; D009804:Odontoblasts / Q000166:cytology / Q000201:enzymology*; D015675:Osteocalcin / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D019246:Tooth Preparation; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000378:metabolism; D014945:Wound Healing
chemical_list: D012333:RNA, Messenger; D015675:Osteocalcin; C002744:3-nitrotyrosine; D014443:Tyrosine; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D000469:Alkaline Phosphatase