title: Effects of heat stress and starvation on clonal odontoblast-like cells.
abstract: BACKGROUND
  Heat stress during restorative procedures, particularly under severe starvation conditions, can trigger damage to dental pulp. In the present study, we examined effects of heat stress on odontoblastic activity and inflammatory responses in an odontoblast-like cell line (KN-3) under serum-starved conditions.
  
  
  METHODS
  Viability, nuclear structures, and inflammatory responses of KN-3 cells were examined in culture medium containing 10% or 1% serum after exposure to heat stress at 43°C for 45 minutes. Gene expression of extracellular matrices, alkaline phosphatase activity, and detection of extracellular calcium deposition in cells exposed to heat stress were also examined.
  
  
  RESULTS
  Reduced viability and apoptosis were transiently induced in KN-3 cells during the initial phases after heat stress; thereafter, cells recovered their viability. The cytotoxic effects of heat stress were enhanced under serum-starved conditions. Heat stress also strongly up-regulated expression of heat shock protein 25 as well as transient expression of tumor necrosis factor-alpha, interleukin-6, and cyclooxygenase-2 in KN-3 cells. In contrast, expression of type-1 collagen, runt-related transcription factor 2, and dentin sialophosphoprotein were not inhibited by heat stress although starvation suppressed ALP activity and delayed progression of calcification.
  
  
  CONCLUSIONS
  Odontoblast-like cells showed thermoresistance with transient inflammatory responses and without loss of calcification activity, and their thermoresistance and calcification activity were influenced by nutritional status.
authors.affiliation: Department of Odontology, Section of Operative Dentistry and Endodontology, Fukuoka Dental College, Fukuoka, Japan. morotomi@college.fdcnet.ac.jp
authors.forename: Takahiko
authors.initials: T
authors.lastname: Morotomi
authors.forename: Chiaki
authors.initials: C
authors.lastname: Kitamura
authors.forename: Takashi
authors.initials: T
authors.lastname: Toyono
authors.forename: Toshinori
authors.initials: T
authors.lastname: Okinaga
authors.forename: Ayako
authors.initials: A
authors.lastname: Washio
authors.forename: Noriko
authors.initials: N
authors.lastname: Saito
authors.forename: Tatsuji
authors.initials: T
authors.lastname: Nishihara
authors.forename: Masamichi
authors.initials: M
authors.lastname: Terashita
authors.forename: Hisashi
authors.initials: H
authors.lastname: Anan
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D017209:Apoptosis / Q000502:physiology; D002113:Calcification, Physiologic / Q000502:physiology; D002470:Cell Survival; D002478:Cells, Cultured; D002999:Clone Cells; D016895:Culture Media, Serum-Free; D018869:Heat-Shock Response / Q000502:physiology*; D006358:Hot Temperature; D018836:Inflammation Mediators / Q000378:metabolism; D009804:Odontoblasts / Q000166:cytology / Q000502:physiology*; D051381:Rats; D013312:Stress, Physiological / Q000502:physiology*
chemical_list: D016895:Culture Media, Serum-Free; D018836:Inflammation Mediators