title: Combined effect of soy isoflavones and vitamin D3 on bone loss in ovariectomized rats.
abstract: OBJECTIVE
  Several studies have shown that soy isoflavones have estrogen-like activities and might constitute an alternative to hormone replacement treatment. The present study investigated the effects of soy isoflavones alone and combined with vitamin D3 on prevention of bone loss.
  
  
  METHODS
  Sprague-Dawley rats were sham-operated (n = 8) or ovariectomized (OVX; n = 40), and then the OVX rats were randomly assigned to five groups that were untreated or treated for 14 wk with vitamin D3, 17β-estradiol, soy isoflavone extract (SIE), or vitamin D3 plus SIE. The effects of the isoflavones and 1α,25(OH)(2)D(3) on cultured osteoblasts and osteoclasts also were investigated.
  
  
  RESULTS
  In OVX rats, the bone mineral density and trabecular bone volume loss were improved by 17β-estradiol, SIE, or SIE plus vitamin D3 treatment. SIE treatment was more effective than vitamin D3 or 17β-estradiol in inhibiting increases in serum tumor necrosis factor-α levels and osteoblast osteoprotegerin expression. SIE plus vitamin D3 was more effective in increasing osterix expression than each alone. Bone cell cultures showed that the isoflavones induced preosteoblasts to differentiate into osteoblasts and increased osteoblast mineralization. Isoflavones inhibited preosteoclasts and osteoclast proliferation and decreased osteoclast resorption. The combination of isoflavones plus 1α,25(OH)(2)D(3) showed additive effects on the increase in cell proliferation of cultured preosteoblasts.
  
  
  CONCLUSIONS
  Treatment with soy isoflavones might be an alternative to hormone replacement therapy in decreasing bone loss from postmenopausal estrogen deficiency. In addition, there are further effects on increasing transcription factor osterix expression and preosteoblast proliferation when these were combined with vitamin D3.
authors.affiliation: Department of Biochemistry, Faculty of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Kee-Lung
authors.initials: KL
authors.lastname: Chang
authors.forename: Yu-Chen
authors.initials: YC
authors.lastname: Hu
authors.forename: Bau-Shan
authors.initials: BS
authors.lastname: Hsieh
authors.forename: Hsiao-Ling
authors.initials: HL
authors.lastname: Cheng
authors.forename: Hen-Wei
authors.initials: HW
authors.lastname: Hsu
authors.forename: Li-Wen
authors.initials: LW
authors.lastname: Huang
authors.forename: Shu-Jem
authors.initials: SJ
authors.lastname: Su
mesh_terms: D000469:Alkaline Phosphatase / Q000097:blood; D000818:Animals; D015519:Bone Density / Q000187:drug effects; D002762:Cholecalciferol / Q000008:administration & dosage*; D004195:Disease Models, Animal; D004357:Drug Synergism; D004958:Estradiol / Q000008:administration & dosage; D005260:Female; D006801:Humans; D053583:Interleukin-1beta / Q000097:blood; D007529:Isoflavones / Q000008:administration & dosage*; D010006:Osteoblasts / Q000187:drug effects / Q000473:pathology; D015675:Osteocalcin / Q000097:blood; D010010:Osteoclasts / Q000187:drug effects / Q000473:pathology; D010012:Osteogenesis / Q000187:drug effects / Q000235:genetics; D010024:Osteoporosis / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D010052:Ovariectomy; D048789:Phytoestrogens / Q000008:administration & dosage; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013025:Glycine max / Q000737:chemistry; D014409:Tumor Necrosis Factor-alpha / Q000097:blood
chemical_list: D053583:Interleukin-1beta; D007529:Isoflavones; D048789:Phytoestrogens; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D015675:Osteocalcin; D002762:Cholecalciferol; D004958:Estradiol; D000469:Alkaline Phosphatase