title: Paraquat-induced pulmonary fibrosis starts at an early stage of inflammation in rats.
abstract: OBJECTIVE
  To investigate the starting point of paraquat-induced pulmonary fibrosis in rats.
  
  
  METHODS
  A total of 96 healthy Sprague-Dawley rats were randomly divided into eight groups (n = 12 in each group) including a control and paraquat-poisoning group. Control rats received treatment with saline. Samples were collected at 2, 6, 12, 24, 48, 72 and 120 h after paraquat administered by lavage. All lung tissues were stained with hematoxylin-eosin and Masson's trichrome. Collagen III expressed in bronchoalveolar lavage fluid was detected by ELISA. The α-smooth muscle actin in lung tissue was detected by western blotting.
  
  
  RESULTS
  A rat model of paraquat poisoning was established. Histological examination results indicated that lung fibrosis started in rats 2 h after paraquat poisoning. Compared with the control group, the collagen III protein in bronchoalveolar lavage fluid was significantly upregulated in the 2-h group (α = 0.05) and the same level was maintained in the other poisoning groups. The expression of α-smooth muscle actin in the lung tissue was significantly increased in the 12-h group (α = 0.05) and remained at the same level after 12 h.
  
  
  CONCLUSIONS
  The paraquat-induced pulmonary fibrosis in rats began at an early stage of inflammation. The therapy of antifibrosis should be applied at an early time of paraquat poisoning.
authors.affiliation: Department of Critical Care Medicine, Afﬁliated First People's Hospital, Shanghai Jiao Tong University, School of Medicine, Shanghai 200080, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Xie
authors.forename: Ruilan
authors.initials: R
authors.lastname: Wang
authors.forename: Xue
authors.initials: X
authors.lastname: Tang
authors.forename: Ying
authors.initials: Y
authors.lastname: Xiong
authors.forename: Rong
authors.initials: R
authors.lastname: Xu
authors.forename: Xin
authors.initials: X
authors.lastname: Wu
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry; D024061:Collagen Type III / Q000378:metabolism; D004195:Disease Models, Animal; D018450:Disease Progression; D006540:Herbicides / Q000506:poisoning*; D006801:Humans; D007249:Inflammation / Q000139:chemically induced* / Q000276:immunology; D008168:Lung / Q000187:drug effects* / Q000276:immunology; D008297:Male; D010269:Paraquat / Q000506:poisoning*; D011658:Pulmonary Fibrosis / Q000139:chemically induced* / Q000276:immunology; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D000199:Actins; D024061:Collagen Type III; D006540:Herbicides; D010269:Paraquat; C498862:Acta2 protein, rat