title: [Retinoic acid protects neonatal rats from hyperoxia-induced lung injury through down-regulating connective tissue growth factor].
abstract: OBJECTIVE
  To explore the mechanism of retinoic acid (RA)　protection　against hyperoxia-induced lung injury.
  
  
  METHODS
  Ninety Sprague-Dawley rats were randomly assigned into three groups (n=30 each): air control group (exposed to air) and hyperoxia groups (exposed to 85% oxygen) with and without RA treatment. The RA-treated hyperoxia group received an intraperitoneal injection of RA (500 μg/kg) daily. Lungs were removed by tnoracotomy 4, 7 and 14 days after exposure. Radical alveolar counts (RAC) were observed by hematoxylin and eosin staining under a light microscope. The mRNA level of CTGF in lungs was detected by reverse transcriptase polymerase chain reaction (RT-PCR). The expression of CTGF protein in lungs was detected by immunohistochemistry.
  
  
  RESULTS
  With the prolonged hyperoxia exposure, the lungs developed inflammatory cell infiltration, alveolar structure disorders, a decrease in the number of alveoli, and alveolar interstitial thickening in the hyperoxia groups with and without RA treatment. Pathological changes in the RA-treated hyperoxia group were less severe than the untreated hyperoxia group. The CTGF mRNA and protein expression were up-regulated in the hyperoxia groups with and without RA treatment 7 and 14 days after exposure compared with the air control group. Significantly decreased CTGF mRNA and protein expression were noted in the RA-treated hyperoxia group compared with the untreated hyperoxia group 14 days after exposure.
  
  
  CONCLUSIONS
  The expression of CTGF mRNA and protein increases in neonatal rats with hyperoxia-induced lung injury. RA may provide protections against the lung injury possibly through down-regulating CTGF expression.
authors.affiliation: Neonatal Diagnosis and Treatment Center, Children's Hospital of Chongqing Medical University, Chongqing 400014, China.
authors.forename: Ya-Li
authors.initials: YL
authors.lastname: Xu
authors.forename: Yi-Ji
authors.initials: YJ
authors.lastname: Chen
authors.forename: Ya-Wei
authors.initials: YW
authors.lastname: Zhang
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D055513:Connective Tissue Growth Factor / Q000235:genetics*; D019610:Cytoprotection; D015536:Down-Regulation; D018496:Hyperoxia / Q000150:complications* / Q000378:metabolism; D008168:Lung / Q000378:metabolism / Q000473:pathology; D055370:Lung Injury / Q000517:prevention & control*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014212:Tretinoin / Q000494:pharmacology*
chemical_list: D012333:RNA, Messenger; D055513:Connective Tissue Growth Factor; D014212:Tretinoin