title: Angiotensin II type 1 receptor antagonist attenuates lung fibrosis in hyperoxia-exposed newborn rats.
abstract: Bronchopulmonary dysplasia (BPD) remains a major cause of morbidity and mortality during the first year of life, and many infants have significant respiratory problems throughout childhood. Currently no effective therapy is clinically available to prevent the long-term pulmonary sequelae of BPD. Previous research has demonstrated that the renin-angiotensin system is up-regulated in human lung fibroblasts. Angiotensin II type 1 receptor (AT₁R) antagonists and AT₁R short interfering RNA diminished hyperoxia-increased collagen expression, whereas AT₂R antagonists did not have any effects on these hyperoxia-induced changes. The in vivo therapeutic effects of AT₁R antagonists on hyperoxia-induced lung fibrosis remain unknown. The present study assessed the effects of an AT₁R antagonist (losartan) on preventing hyperoxia-induced lung fibrosis in newborn rats. Rat pups were exposed to 7 days of > 95% O₂ and an additional 2 weeks of 60% O₂. AT₁R antagonist-treated pups were injected intraperitoneally with losartan at a dose of 10 mg/kg/day from postnatal days 1 to 7 and a dose of 5 mg/kg/day from postnatal days 8 to 21. Control group pups were injected with an equal volume of normal saline. AT₁R antagonist treatment attenuated the hyperoxia-induced lung fibrosis on postnatal days 7 and 21 and also decreased the hyperoxia-induced expression of extracellular signal-regulated protein kinase and α-smooth muscle actin. AT₁R antagonist treatment did not affect body weight or lung weight of the rats. These data suggest that AT₁R antagonist may offer a novel therapeutic strategy for preventing hyperoxia-induced lung fibrosis.
authors: Department of Anatomy, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.
authors: Hsiu-Chu
authors: HC
authors: Chou
authors: Yaw-Dong
authors: YD
authors: Lang
authors: Leng-Fang
authors: LF
authors: Wang
authors: Tzu-Ying
authors: TY
authors: Wu
authors: Yu-Fang
authors: YF
authors: Hsieh
authors: Chung-Ming
authors: CM
authors: Chen
mesh_terms: D000199:Actins / Q000096:biosynthesis; D047228:Angiotensin II Type 1 Receptor Blockers / Q000627:therapeutic use*; D000818:Animals; D000831:Animals, Newborn; D015153:Blotting, Western; D001835:Body Weight / Q000187:drug effects; D003094:Collagen / Q000096:biosynthesis / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000096:biosynthesis; D005260:Female; D018496:Hyperoxia / Q000150:complications* / Q000473:pathology; D019808:Losartan / Q000494:pharmacology; D008168:Lung / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D009929:Organ Size / Q000187:drug effects; D011247:Pregnancy; D011658:Pulmonary Fibrosis / Q000188:drug therapy* / Q000209:etiology / Q000473:pathology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D000199:Actins; D047228:Angiotensin II Type 1 Receptor Blockers; D003094:Collagen; D048049:Extracellular Signal-Regulated MAP Kinases; D019808:Losartan; D012333:RNA, Messenger; C498862:Acta2 protein, rat