title: Sleep deprivation induces abnormal bone metabolism in temporomandibular joint.
abstract: BACKGROUND
  The purpose of this study was to explore the effect of experimental sleep deprivation (SD) on the temporomandibular joint (TMJ) of rats and the possible mechanism related to abnormal bone metabolism.
  
  
  METHODS
  SD was induced by a modified multiple platform method and assessed by serum adrenocorticotropic hormone (ACTH) level. TMJs were detached and stained with hematoxylin and eosin (H&E). Expression of interleukin-1β (IL-1β), tumor necrosis factor alpha (TNF-α), osteoprotegerin (OPG) and receptor activator of nuclear factor kappa B ligand (RANKL) was evaluated by quantitative reverse transcription polymerase chain reaction, H&E staining, immunohistochemical staining and enzyme linked immunosorbent assay.
  
  
  RESULTS
  Compared with controls, SD significantly increased serum ACTH, indicating that the SD model was successful. In the SD group, H&E staining revealed greater vessel hyperplasia in the synovial membrane and thicker hypertrophic layers in condylar cartilages. Compared with controls, RNA and protein expression of the inflammatory factors IL-1β and TNF-α and the bone metabolism-related factor RANKL increased in condylar cartilage in the SD group, whereas OPG and the OPG/RANKL ratio decreased. Immunohistochemical staining revealed that OPG/RANKL immunopositive cells were mainly located in hypertrophic layers.
  
  
  CONCLUSIONS
  These results suggest that sleep deprivation might play an important role in the occurrence and development of temporomandibular disorders, which may occur through abnormal secretion of inflammatory and bone metabolism-related factors.
authors.affiliation: Department of Dental Implantology Centre, School of Stomatology, Capital Medical University Beijing 100050, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Geng
authors.affiliation: Department of Stomatology, Jinan Military General Hospital Number 25, Shi Fan Lu, Jinan City 250031, Shandong Province, China.
authors.forename: Gaoyi
authors.initials: G
authors.lastname: Wu
authors.affiliation: Department of Stomatology, PLA Navy General Hospital Beijing 100048, China.
authors.forename: Fei
authors.initials: F
authors.lastname: Huang
authors.affiliation: College of Stomatology, Shandong University Number 44, Wen Hua Xi Lu, Jinan City 250012, Shandong Province, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: Department of Stomatology, The First Hospital Affiliated to The PLA General Hospital Beijing 100048, China.
authors.forename: Jia
authors.initials: J
authors.lastname: Nie
authors.affiliation: Department of Stomatology, Jinan Military General Hospital Number 25, Shi Fan Lu, Jinan City 250031, Shandong Province, China.
authors.forename: Yuhong
authors.initials: Y
authors.lastname: He
authors.affiliation: Department of Stomatology, Jinan Military General Hospital Number 25, Shi Fan Lu, Jinan City 250031, Shandong Province, China ; Department of Orthodontics, Jinan Stomatological Hospital Number 101, Jing Liu Road, Jinan City 250001, Shandong Province, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Chen
keywords: Sleep deprivation; bone metabolism; inflammation; temporomandibular joint