title: Expression of TGF-β1 in the blood during fracture repair in an estrogen-deficient rat model.
abstract: OBJECTIVE
  Previous studies have reported that osteoporosis due to estrogen deficiency influences fracture healing. Transforming growth factor (TGF-b) has been found to be involved in fracture healing via the regulation of the differentiation and activation of osteoblasts and osteoclasts. The current study aimed to determine the effects of estrogen on the expression of TGF-β1 during fracture healing in ovariectomized rats.
  
  
  METHODS
  Thirty female Sprague-Dawley rats weighing 200-250 g were assigned to: (i) a sham-operated group that was given a normal saline; (ii) an ovariectomized control group that was given a normal saline; or (iii) an ovariectomized + estrogen (100 mg/kg/day) group that was treated with conjugated equine estrogen. The right femur of all rats was fractured, and a Kirschner wire was inserted six weeks post-ovariectomy. Treatment with estrogen was given for another six weeks post-fracture. At the end of the study, blood samples were taken, and the right femur was harvested and subjected to biomechanical strength testing.
  
  
  RESULTS
  The percentage change in the plasma TGF-β1 level before treatment was significantly lower in the ovariectomized control and estrogen groups when compared with the sham group (p<0.001). After six weeks of treatment, the percentage change in the plasma TGF-β1 level in the estrogen group was significantly higher compared with the level in the ovariectomized control group (p = 0.001). The mean ultimate force was significantly increased in the ovariectomized rats treated with estrogen when compared with the ovariectomized control group (p = 0.02).
  
  
  CONCLUSIONS
  These data suggest that treatment with conjugated equine estrogen enhanced the strength of the healed bone in estrogen-deficient rats by most likely inducing the expression of TGF-β1.
authors.affiliation: Department of Anatomy, Universiti Kebangsaan Malaysia Medical Center, Kuala Lumpur, Malaysia. abdalla177@gmail.com
authors.forename: Mohamed Abdalla
authors.initials: MA
authors.lastname: Estai
authors.forename: Farihah
authors.initials: F
authors.lastname: Suhaimi
authors.forename: Srijit
authors.initials: S
authors.lastname: Das
authors.forename: Ahmad Nazrun
authors.initials: AN
authors.lastname: Shuid
authors.forename: Zahiah
authors.initials: Z
authors.lastname: Mohamed
authors.forename: Ima-Nirwana
authors.initials: IN
authors.lastname: Soelaiman
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D004967:Estrogens / Q000008:administration & dosage / Q000172:deficiency*; D005260:Female; D005264:Femoral Fractures / Q000097:blood* / Q000188:drug therapy / Q000209:etiology; D017102:Fracture Healing / Q000187:drug effects* / Q000502:physiology; D010024:Osteoporosis / Q000150:complications* / Q000378:metabolism; D010052:Ovariectomy; D010865:Pilot Projects; D051381:Rats; D017207:Rats, Sprague-Dawley; D053773:Transforming Growth Factor beta1 / Q000097:blood*
chemical_list: D004967:Estrogens; D053773:Transforming Growth Factor beta1