title: [Effects of hyperoxia on lung vascular development and expression of angiopoietin-1 in neonatal rat lungs].
abstract: OBJECTIVE
  To study the effects of prolonged 85% oxygen exposure on lung vascular development and the expression of angiopoietin-1 (Ang-1) in the neonatal rat lungs.
  
  
  METHODS
  Ninety-six Sprague-Dawley rat pups were randomly exposed to air (control group) and 85% oxygen (experimental group) 6 hrs after birth. The rats were sacrificed 3, 7 and 14 days after exposure and their lungs were sampled. The lung sections were stained with hematoxylin and eosin for histological evaluation and analysis of vessel volume density. Expressions of angiopoietin-1 (Ang-1) in lung tissue were measured by immunohistochemistry. Expression of Ang-1 protein and mRNA was detected by Western Blot and Real time-PCR.
  
  
  RESULTS
  After being exposed to 85% oxygen for 14 days, lung tissues had pathological changes as "new" bronchopulmonary dysplasia (BPD). The RAC on day 7 and day 14 in experimental group decreased significantly as compared with the control group [(10.55 ± 0.13) vs. (11.74 ± 0.19), (12.47 ± 0.05) vs. (15.03 ± 0.16), P < 0.05]. The X-ray showed that the diameter of lung vessel was much smaller and the vessels had less branches in experimental group compared with the control group on day 14. The vessel volume density on day 14 in experimental group decreased significantly as compared with the control group [(3.55 ± 0.09) vs. (6.03 ± 0.16), P < 0.05]. Immunohistochemistry and Western blotting showed that the expressions of Ang-1 protein on day 7 and day 14 in the experimental group decreased significantly as compared with the control group [(4.27 ± 0.34) vs. (3.10 ± 0.29), P < 0.05, (5.65 ± 0.49) vs. (3.21 ± 0.28), P < 0.01], [(0.88 ± 0.31) vs. (0.41 ± 0.12), P < 0.05, (0.90 ± 0.29) vs. (0.21 ± 0.06), P < 0.01]. The expressions of Ang-1 mRNA on day 7 and day 14 in the experimental group also decreased significantly as compared with the control group [(0.85 ± 0.14) vs. (0.44 ± 0.21), P < 0.05, (0.87 ± 0.24) vs. (0.24 ± 0.05), P < 0.01].
  
  
  CONCLUSIONS
  Prolonged exposure of high concentration of oxygen may cause impairment of lung vascular development by inhibiting expression of Ang-1 in neonatal rats, which is likely to contribute to pathogenesis of BPD.
authors.affiliation: Department of Pediatrics, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: Fei
authors.initials: F
authors.lastname: Liang
authors.forename: Jian-xing
authors.initials: JX
authors.lastname: Zhu
authors.forename: Hong-ping
authors.initials: HP
authors.lastname: Xia
authors.forename: Hui-ping
authors.initials: HP
authors.lastname: Li
authors.forename: Lü-chang
authors.initials: LC
authors.lastname: Zhu
mesh_terms: D042683:Angiopoietin-1 / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn; D018496:Hyperoxia; D008168:Lung / Q000098:blood supply / Q000378:metabolism*; D011651:Pulmonary Artery / Q000254:growth & development*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
chemical_list: D042683:Angiopoietin-1; C467629:Angpt1 protein, rat; D012333:RNA, Messenger; D042461:Vascular Endothelial Growth Factor A; C467498:vascular endothelial growth factor A, rat