title: Prevention of bone loss by injection of insulin-like growth factor-1 after sciatic neurectomy in rats.
abstract: OBJECTIVE
  Injection of insulin-like growth factor-1 (IGF-1) can prevent bone loss in sciatic nerve transaction rats. We try to investigate the action mechanism of IGF-1 on bone formation.
  
  
  METHODS
  A total of 40 adult male Spragne-Dawley rats were divided into two groups (experimental group and control group) with 20 animals in each. Sciatic neurectomy was performed to model disuse osteoporosis in all rats. IGF-1 was administered in experimental group with the dose of 100 microgramme/kilogram per day for 3 days. Meanwhile, the rats in control group were treated with saline. Bone mineral density was measured by dual-energy X-ray absorptiometry 4 and 6 weeks after neurectomy respectively. Expression of Osterix and Runx2 was determined by reverse transcription-polymerase chain reaction (RT-PCR) assay.
  
  
  RESULTS
  There was a significant increase in the bone mineral density of experimental group compared with control group. There was a significant decrease in the level of receptor activator of nuclear factor-kappaB-ligand but an increase in the level of osteoprotegerin 4 and 6 weeks after neurectomy in the experimental group compared with control one. The expression of Osterix and Runx2 was up-regulated in the bone marrow of experimental group compared with control group.
  
  
  CONCLUSIONS
  IGF-1 can increase bone formation by stimulation of osteoblast number and activity, and reduce bone resorption by restriction of differentiation of osteoclast, suggesting that IGF-1 may improve the therapeutic efficacy for disuse osteoporosis.
authors.affiliation: Xi'an Jiaotong University Medical School, Xi'an 710049, China.
authors.forename: Hai-Biao
authors.initials: HB
authors.lastname: Sun
authors.forename: Jun-Chang
authors.initials: JC
authors.lastname: Chen
mesh_terms: D000818:Animals; D015519:Bone Density / Q000187:drug effects; D001862:Bone Resorption / Q000517:prevention & control*; D002454:Cell Differentiation; D050659:Core Binding Factor Alpha 1 Subunit / Q000378:metabolism; D007150:Immunohistochemistry; D007267:Injections; D007334:Insulin-Like Growth Factor I / Q000008:administration & dosage; D008297:Male; D010006:Osteoblasts / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012584:Sciatic Nerve / Q000601:surgery*; D014157:Transcription Factors / Q000378:metabolism; D015854:Up-Regulation / Q000502:physiology
chemical_list: D050659:Core Binding Factor Alpha 1 Subunit; C493717:Runx2 protein, rat; C495181:Sp7 protein, rat; D014157:Transcription Factors; D007334:Insulin-Like Growth Factor I