title: Ovariectomy and genes encoding core circadian regulatory proteins in murine bone.
abstract: CONCLUSIONS
  This study investigated the influence of ovarian hormone deficiency on core circadian regulatory protein (CCRP) in the context of bone loss. Our data suggest that ovarian hormone deficiency disrupts diurnal rhythmicity and CCRP expression in bone. Further studies should determine if chronobiology provides a novel therapeutic target for osteoporosis intervention.
  
  
  BACKGROUND
  CCRP synchronize metabolic activities and display an oscillatory expression profile in murine bone. In vitro studies using bone marrow mesenchymal stromal/stem cells have demonstrated that the CCRP is present and can be regulated within osteoblast progenitors. In vivo studies have shown that the CCRP regulates bone mass via leptin/neuroendocrine pathways. The current study used an ovariectomized murine model to test the hypothesis that ovarian hormone deficiency is associated with either an attenuation and/or temporal phase shift of the CCRP oscillatory expression in bone and that these changes are correlated with the onset of osteoporosis.
  
  
  METHODS
  Sham-operated controls and ovariectomized female C57BL/6 mice were euthanized at 4-h intervals 2 weeks post-operatively.
  
  
  RESULTS
  Ovariectomy attenuated the oscillatory expression of CCRP mRNAs in the femur and vertebra relative to the controls and reduced the wheel-running activity profile.
  
  
  CONCLUSIONS
  Ovarian hormone deficiency modulates the expression profile of the CCRP with potential impact on bone marrow mesenchymal stem cell lineage commitment.
authors.affiliation: Department of Nutritional Sciences, Oklahoma State University, 423 HES, Stillwater, OK 74078, USA. bjsmith@okstate.edu
authors.forename: B J
authors.initials: BJ
authors.lastname: Smith
authors.forename: G M
authors.initials: GM
authors.lastname: Sutton
authors.forename: X
authors.initials: X
authors.lastname: Wu
authors.forename: G
authors.initials: G
authors.lastname: Yu
authors.forename: B C
authors.initials: BC
authors.lastname: Goh
authors.forename: T
authors.initials: T
authors.lastname: Hebert
authors.forename: G
authors.initials: G
authors.lastname: Pelled
authors.forename: Z
authors.initials: Z
authors.lastname: Gazit
authors.forename: D
authors.initials: D
authors.lastname: Gazit
authors.forename: A A
authors.initials: AA
authors.lastname: Butler
authors.forename: J M
authors.initials: JM
authors.lastname: Gimble
mesh_terms: D000818:Animals; D002940:Circadian Rhythm / Q000235:genetics / Q000502:physiology*; D056925:Circadian Rhythm Signaling Peptides and Proteins / Q000096:biosynthesis* / Q000235:genetics; D004195:Disease Models, Animal; D004967:Estrogens / Q000172:deficiency / Q000502:physiology*; D005260:Female; D005269:Femur / Q000378:metabolism; D020869:Gene Expression Profiling / Q000379:methods; D005786:Gene Expression Regulation / Q000502:physiology; D008159:Lumbar Vertebrae / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009043:Motor Activity / Q000502:physiology; D010024:Osteoporosis / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology*; D010052:Ovariectomy; D012333:RNA, Messenger / Q000235:genetics; D013314:Stress, Mechanical; D055114:X-Ray Microtomography / Q000379:methods
chemical_list: D056925:Circadian Rhythm Signaling Peptides and Proteins; D004967:Estrogens; D012333:RNA, Messenger