title: Receptor activator of nuclear factor-κB ligand and sclerostin expression in osteocytes of alveolar bone in rats with ligature-induced periodontitis.
abstract: BACKGROUND
  Osteocytes are increasingly recognized as significant sources of osteoclast differentiation factor, receptor activator of nuclear factor-κB ligand (RANKL), and osteoblast differentiation inhibitory factor, sclerostin. In this study, RANKL and sclerostin expression of osteocytes is investigated in rats with ligature-induced periodontitis.
  
  
  METHODS
  Rats were divided into control and periodontitis groups, and periodontitis was induced by ligature on the mandibular first molars. At 1, 3, 10, and 20 days after ligature, histologic analyses of alveolar bone (AB) and osteoid areas in the molar furcation were performed. The numbers of osteoclasts and RANKL- and sclerostin-positive osteocytes were estimated by tartrate-resistant acid phosphatase staining and immunohistochemistry, respectively.
  
  
  RESULTS
  The AB area gradually decreased at day 10 after ligature and increased at day 20. The number of osteoclasts markedly increased at day 3 and then decreased. Conversely, osteoid formation was suppressed up to day 3 and then showed a remarkable increase above control level at day 20. The number of RANKL-positive osteocytes increased at days 1 and 3 and then decreased. Sclerostin-positive osteocytes markedly increased at days 3 and 10 but decreased below control level at day 20.
  
  
  CONCLUSIONS
  These results show that AB loss is accompanied by enhanced osteoclast formation and suppressed osteoid formation. Osteocytes express RANKL when osteoclast formation increases, and they express sclerostin when osteoid formation is suppressed. Conversely, osteocytic sclerostin expression decreases when osteoid formation increases. These findings suggest that osteocytes may be important in AB loss via RANKL and sclerostin expression in periodontitis.
authors: Department of Oral Biology, Yonsei University College of Dentistry, Seoul, Republic of Korea.
authors: Ji-Hye
authors: JH
authors: Kim
authors: Dong-Eun
authors: DE
authors: Lee
authors: Jeong-Heon
authors: JH
authors: Cha
authors: Eun-Jung
authors: EJ
authors: Bak
authors: Yun-Jung
authors: YJ
authors: Yoo
mesh_terms: D000135:Acid Phosphatase / Q000032:analysis; D016301:Alveolar Bone Loss / Q000378:metabolism / Q000473:pathology; D000539:Alveolar Process / Q000737:chemistry* / Q000473:pathology; D000818:Animals; D017209:Apoptosis / Q000502:physiology; D001857:Bone Matrix / Q000737:chemistry / Q000473:pathology; D019485:Bone Morphogenetic Proteins / Q000032:analysis*; D005819:Genetic Markers; D007527:Isoenzymes / Q000032:analysis; D007963:Leukocytes, Mononuclear / Q000473:pathology; D008297:Male; D008336:Mandibular Diseases / Q000378:metabolism / Q000473:pathology; D009504:Neutrophils / Q000473:pathology; D010010:Osteoclasts / Q000473:pathology; D010011:Osteocytes / Q000737:chemistry*; D010518:Periodontitis / Q000378:metabolism* / Q000473:pathology; D053245:RANK Ligand / Q000032:analysis*; D011897:Random Allocation; D051381:Rats; D011916:Rats, Inbred F344; D000071681:Tartrate-Resistant Acid Phosphatase; D013997:Time Factors
chemical_list: D019485:Bone Morphogenetic Proteins; D005819:Genetic Markers; D007527:Isoenzymes; D053245:RANK Ligand; C486031:Sost protein, rat; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase
keywords: Osteocytes; RANK ligand; periodontitis; sclerostin protein, rat