title: Low-magnitude mechanical vibration regulates expression of osteogenic proteins in ovariectomized rats.
abstract: OBJECTIVE
  The present study aimed to investigate the impact of low-magnitude and high-frequency mechanical vibration with various lengths of resting period incorporated between loading cycles on the expression of osteogenesis-related proteins in a rat model of osteoporosis.
  
  
  METHODS
  The rats in the mechanical loading groups received low-magnitude and high-frequency vibration (35 Hz and acceleration of 0.25 g, 15 min/day) for 8 weeks. Bilateral humeral heads and femoral heads were then isolated, and protein levels of bone morphogenetic protein 2 (BMP-2), extracellular signal-regulated kinase 1/2 (ERK1/2), phosphorylated ERK1/2 (p-ERK1/2), runt-related transcription factor 2 (Runx2) and osteocalcin (OCN) were determined by Western blotting.
  
  
  RESULTS
  Increased levels of BMP-2, Runx2 and OCN were observed in rats receiving mechanical vibration. Total ERK1/2 protein remained unchanged, whereas the level of activated ERK1/2 (p-ERK1/2) increased after mechanical vibration. Vibration with incorporated resting period, regardless of length, was more effective in inducing expression of these osteogenic proteins, and the vibration with 7-day resting period had the most profound impact.
  
  
  CONCLUSIONS
  Signals from low-magnitude and high-frequency mechanical vibration upregulated the expression of BMP-2 and Runx2, activated the ERK1/2 signaling pathway, and consequently led to increased expression of OCN. The anabolic effect of mechanical stimulation was enhanced with incorporation of resting period between loadings, and the one with 7-day resting period exhibited the strongest effect among all. Our results could provide a reference for development of mechanical stimulation as a non-pharmacological intervention for osteoporosis.
authors.affiliation: Department of Orthopaedics Trauma, First Hospital of Jilin University, China; Department of Orthopaedics Trauma, Honghui Hospital, Xi'an Jiaotong University College of Medicine, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Li
authors.affiliation: Department of Neurosurgery, First Hospital of Jilin University, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wu
authors.affiliation: Department of Orthopaedics Trauma, First Hospital of Jilin University, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Tan
authors.affiliation: Operating Theater, First Hospital of Jilin University, China.
authors.forename: Degong
authors.initials: D
authors.lastname: Mu
authors.affiliation: Department of Orthopaedics Trauma, First Hospital of Jilin University, China. Electronic address: swyxgc@126.com.
authors.forename: Dong
authors.initials: D
authors.lastname: Zhu
authors.affiliation: Department of Orthopaedics Trauma, First Hospital of Jilin University, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Orthopaedics Trauma, First Hospital of Jilin University, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Zhao
mesh_terms: D000818:Animals; D019485:Bone Morphogenetic Proteins / Q000378:metabolism*; D005260:Female; D005786:Gene Expression Regulation; D040542:Mechanotransduction, Cellular; D010012:Osteogenesis; D010024:Osteoporosis / Q000175:diagnosis / Q000503:physiopathology* / Q000628:therapy*; D010052:Ovariectomy; D010812:Physical Stimulation / Q000379:methods; D051381:Rats; D017207:Rats, Sprague-Dawley; D016896:Treatment Outcome; D014732:Vibration
chemical_list: D019485:Bone Morphogenetic Proteins
keywords: Low-magnitude mechanical vibration; Osteogenic proteins; Osteoporosis