title: Increased activity of osteocyte autophagy in ovariectomized rats and its correlation with oxidative stress status and bone loss.
abstract: OBJECTIVE
  The objectives of the present study were to investigate ovariectomy on autophagy level in the bone and to examine whether autophagy level is associated with bone loss and oxidative stress status.
  
  
  METHODS
  36 female Sprague-Dawley rats were randomly divided into sham-operated (Sham), and ovariectomized (OVX) rats treated either with vehicle or 17-β-estradiol. At the end of the six-week treatment, bone mineral density (BMD) and bone micro-architecture in proximal tibias were assessed by micro-CT. Serum 17β-estradiol (E2) level were measured. Total antioxidant capacity (T-AOC), superoxide dismutase (SOD) activity, catalase (CAT) activity in proximal tibia was also determined. The osteocyte autophagy in proximal tibias was detected respectively by Transmission Electron Microscopy (TEM), immunofluorescent histochemistry (IH), realtime-PCR and Western blot. In addition, the spearman correlation between bone mass, oxidative stress status, serum E2 and autophagy were analyzed.
  
  
  RESULTS
  Ovariectomy increased Atg5, LC3, and Beclin1 mRNA and proteins expressions while decreased p62 expression. Ovariectomy also declined the activities of T-AOC, CAT, and SOD. Treatment with E2 prevented the reduction in bone mass as well as restored the autophagy level. Furthermore, LC3-II expression was inversely correlated with T-AOC, CAT, and SOD activities. A significant inverse correlation between LC3-II expression and BV/TV, Tb.N, BMD in proximal tibias was found.
  
  
  CONCLUSIONS
  Ovariectomy induced oxidative stress, autophagy and bone loss. Autophagy of osteocyte was inversely correlated with oxidative stress status and bone loss.
authors: Department of Orthopaedic Surgery, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, 1665 Kongjiang Road, Shanghai 200092, China. Electronic address: yuesjtu@126.com.
authors: Yuehua
authors: Y
authors: Yang
authors: Department of Orthopaedic Surgery, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, 1665 Kongjiang Road, Shanghai 200092, China. Electronic address: zxf272@126.com.
authors: Xinfeng
authors: X
authors: Zheng
authors: Department of Orthopaedic Surgery, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, 1665 Kongjiang Road, Shanghai 200092, China. Electronic address: libo@126.com.
authors: Bo
authors: B
authors: Li
authors: Department of Orthopaedic Surgery, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, 1665 Kongjiang Road, Shanghai 200092, China. Electronic address: jiangsd@126.com.
authors: Shengdan
authors: S
authors: Jiang
authors: Department of Orthopaedic Surgery, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, 1665 Kongjiang Road, Shanghai 200092, China. Electronic address: leisheng_jiang@126.com.
authors: Leisheng
authors: L
authors: Jiang
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism; D001343:Autophagy / Q000187:drug effects; D000071187:Autophagy-Related Protein 5; D000071186:Beclin-1; D015519:Bone Density; D002384:Catalysis; D004958:Estradiol / Q000097:blood / Q000494:pharmacology; D005260:Female; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism; D010011:Osteocytes / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology*; D010024:Osteoporosis / Q000378:metabolism / Q000503:physiopathology*; D010052:Ovariectomy / Q000009:adverse effects*; D018384:Oxidative Stress; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013482:Superoxide Dismutase; D013977:Tibia / Q000378:metabolism / Q000473:pathology / Q000648:ultrastructure
chemical_list: D000975:Antioxidants; D051017:Apoptosis Regulatory Proteins; D000071187:Autophagy-Related Protein 5; D000071186:Beclin-1; D004958:Estradiol; D008869:Microtubule-Associated Proteins; D011506:Proteins; D013482:Superoxide Dismutase; C545865:Atg5 protein, rat; C512829:Becn1 protein, rat; C526109:Anxa3 protein, rat
keywords: Autophagy; Estrogen; Osteoporosis; Oxidative stress