title: [Antagonistic effects of estrogen on iron-induced bone resorption and its mechanism].
abstract: OBJECTIVE
  To explore the antagonistic effect of estrogen on iron-induced bone resorption and the role of oxidative stress.
  
  
  METHODS
  In vivo, 8-week-old female imprinting control region mice were randomly divided into 3 groups of ferritin (F), ovariectomy (OVX) and F+OVX. Intervention was made by ferric ammonium citrate (FAC) and OVX. Serum levels of ferritin, malondialdehyde (MDA) and superoxide dismutase (SOD) were measured. The expression changes of TRAP, CTR, matrix metallopeptidase 9 (MMP9) and CTK derived from murine bilateral tibia were detected by reverse transcription-polymerase chain reaction (RT-PCR). A high-resolution micro-computed tomography was utilized for scanning distal femur. In vitro, RAW264.7 cells were used and intervened by FAC and estradiol. Tartrate resistant acid phosphatase (TRAP) staining was performed and wine-red TRAP positive cells were counted. ROS level was detected by 2', 7'-dichloro-dihydrofluorescein diacetate (DCFH-DA) with a multi-detection reader.
  
  
  RESULTS
  The serum ferritin were heightened in F and F+OVX groups [(335.30 ± 44.10) vs (41.38 ± 5.56) µg/L, (324.80 ± 38.60) vs (41.38 ± 5.56) µg/L respectively, P < 0.01]. The trend of MDA level was F+OVX>OVX>F while SOD level was quite opposite. Body mass density of F+OVX group was lower than that of OVX group (0.114 ± 0.013 vs 0.187 ± 0.029 mg/mm³, P < 0.05) or F group (0.114 ± 0.013 vs 0.902 ± 0.064 mg/mm³, P < 0.05).
  TRAP and CTK gene expression of OVX group was lower than that of F+OVX group. However, TRAP, CTR and CTK gene expression of F+OVX group was higher than that of F group. TRAP staining: FAC increased the number of TRAP positive cells (41.7 ± 5.5 vs 20.0 ± 4.0, P < 0.05) while estradiol decreased it (14.8 ± 5.1 vs 41.7 ± 5.5, P < 0.05). DCFH-DA test show that reactive oxygen species was elevated by FAC (160% ± 8% vs 100% ± 9%, P < 0.05) and reduced by estradiol (53% ± 13% vs 160% ± 8%, P < 0.05).
  
  
  CONCLUSIONS
  The antagonistic effect of estrogen on iron-induced bone resorption is probably regulated by oxidative stress.
authors.affiliation: Department of Orthopedics, Second Affiliated Hospital, Soochow University, Suzhou 215004, China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Wang
authors.forename: Lulin
authors.initials: L
authors.lastname: Liu
authors.forename: Chao
authors.initials: C
authors.lastname: Gao
authors.forename: Guoyang
authors.initials: G
authors.lastname: Zhao
authors.forename: Guangsi
authors.initials: G
authors.lastname: Shen
authors.forename: Wen
authors.initials: W
authors.lastname: Zhang
authors.forename: Zhanli
authors.initials: Z
authors.lastname: Xie
authors.affiliation: Email: xuyoujia@medmail.com.cn.
authors.forename: Youjia
authors.initials: Y
authors.lastname: Xu
mesh_terms: D000818:Animals; D001862:Bone Resorption; D004958:Estradiol; D004965:Estrogen Antagonists; D004967:Estrogens; D005260:Female; D005269:Femur; D005290:Ferric Compounds; D005293:Ferritins; D005452:Fluoresceins; D007501:Iron; D051379:Mice; D010052:Ovariectomy; D000644:Quaternary Ammonium Compounds; D055114:X-Ray Microtomography
chemical_list: D004965:Estrogen Antagonists; D004967:Estrogens; D005290:Ferric Compounds; D005452:Fluoresceins; D000644:Quaternary Ammonium Compounds; C110423:dihydrofluorescein; C029569:diacetyldichlorofluorescein; D004958:Estradiol; D005293:Ferritins; D007501:Iron; C013531:ferric ammonium citrate