title: [Expressions of RANK, RANKL, and osteoprotegerin in male rats at different ages].
abstract: OBJECTIVE
  To investigate the expression of receptor activator of nuclear factor-κB (RANK), its ligand RANKL, and osteoprotegerin, and observe the effects of αD3 on their expressions in male rats at different ages.
  
  
  METHODS
  Wistar rats at 6 weeks, 6 months, and 24 months (n=15) were examined for mRNA expressions of RANK/RANKL and osteoprotegerin in the left proximal femur using RT-PCR and for their protein expressions in the right femur using immunohistochemistry. RANK/RANKL and osteoprotegerin expressions were also detected in another 15 rats aged 24 months following intragastric administration of 0.05 µg/kg αD3 (3 times a week for 10 weeks).
  
  
  RESULTS
  Compared with 6-week-old rats, 6-month- and 24-month-old rats showed a 6.2-fold and 7.3-fold increase of RANKL mRNA expression, respectively (P<0.05), and osteoprotegerin mRNA levels increased slightly with age. αD3 treatment resulted in significantly increased expression of RANK in 24-month-old rats with a lowered RANKL/osteoprotegerin ratio. RANKL and osteoprotegerin were co-localized in the osteoblasts and chondrocytes. αD3 treatment also caused an increased expression of osteoprotegerin mRNA in 24-month-old rats.
  
  
  CONCLUSIONS
  The age-related increase of the ratio of RANKL/osteoprotegerin mRNA promotes osteoclast activity and bone turnover. αD3 has favorable effect on osteogenesis and suppress bone absorption in the femur possibly by reducing RANK expression and lowering RANKL/osteoprotegerin ratio.
authors.affiliation: Department of Stomatology, Central South University, Changsha, China. zhouxw1128@163.com
authors.forename: Xiong-wen
authors.initials: XW
authors.lastname: Zhou
authors.forename: Ying-chun
authors.initials: YC
authors.lastname: Liu
authors.forename: Xin-chun
authors.initials: XC
authors.lastname: Jian
authors.forename: Yong-hua
authors.initials: YH
authors.lastname: Lei
authors.forename: Ying
authors.initials: Y
authors.lastname: Wu
mesh_terms: D000367:Age Factors; D000818:Animals; D019902:Chondrocytes / Q000378:metabolism*; D005269:Femur / Q000378:metabolism; D008297:Male; D010006:Osteoblasts / Q000378:metabolism*; D053244:Osteoprotegerin / Q000235:genetics / Q000378:metabolism*; D053245:RANK Ligand / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D053246:Receptor Activator of Nuclear Factor-kappa B / Q000235:genetics / Q000378:metabolism*
chemical_list: D053244:Osteoprotegerin; D053245:RANK Ligand; D012333:RNA, Messenger; D053246:Receptor Activator of Nuclear Factor-kappa B; C506032:Tnfrsf11b protein, rat