title: RANKL expression in rat periodontal ligament subjected to a continuous orthodontic force.
abstract: OBJECTIVE
  This study investigated longitudinal changes in receptor activator NF kappa B ligand (RANKL) expression in periodontal ligament (PDL) cells subjected to a continuous orthodontic force.
  
  
  METHODS
  Fifty-five-day-old male Wistar rats were divided into experimental and control groups. The experimental group had the first molars laterally expanded by a continuous orthodontic force. In each group, the horizontal section specimens were embedded in OTC compound and frozen at 0, 1, 3 and 7 days after the expansion. Sections were observed by immunostaining with anti-RANKL and the tartrate-resistant acid phosphatase (TRAP) staining.
  
  
  RESULTS
  Immunoreaction of RANKL and TRAP-positive cells were observed in the distal region of the controls and on the compressed side of the expansion group in the 3 and 7 days. Immunoreaction of RANKL was also observed after 1 day on the compression side of the expansion group, but here TRAP-positive cells were few.
  
  
  CONCLUSIONS
  The experiments have showed that PDL cells are continuously producing RANKL on the PDL pressure side of rats subjected to mechanical stress with a continuous orthodontic force, there was no noticeable the excessive appearance of osteoclasts however. Considering this, it is expected that not only RANKL production but also other cytokines play an important role in the balancing adjustment in the alveolar bone remodeling.
authors.affiliation: Department of Orthodontics, Division of Oral Functional Science, Graduate School of Dental Medicine, Hokkaido University, Sapporo, Japan. takenori@den.hokudai.ac.jp
authors.forename: Takenori
authors.initials: T
authors.lastname: Kim
authors.forename: Asako
authors.initials: A
authors.lastname: Handa
authors.forename: Junichiro
authors.initials: J
authors.lastname: Iida
authors.forename: Shigemitsu
authors.initials: S
authors.lastname: Yoshida
mesh_terms: D000135:Acid Phosphatase / Q000032:analysis; D000818:Animals; D015415:Biomarkers / Q000032:analysis; D002478:Cells, Cultured; D007527:Isoenzymes / Q000032:analysis; D008297:Male; D008963:Molar; D009971:Orthodontics, Corrective; D010010:Osteoclasts / Q000737:chemistry; D010513:Periodontal Ligament / Q000737:chemistry* / Q000166:cytology; D011312:Pressure; D053245:RANK Ligand / Q000032:analysis*; D051381:Rats; D017208:Rats, Wistar; D013314:Stress, Mechanical; D000071681:Tartrate-Resistant Acid Phosphatase
chemical_list: D015415:Biomarkers; D007527:Isoenzymes; D053245:RANK Ligand; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase