title: [Effect of leptin on lung fibrosis of silicosis rats and the correlation between leptin and HIF-1α expressions].
abstract: OBJECTIVE
  To observe the expression of leptin (LP) and its influence on pulmonary fibrosis in experimental rats with silicosis and the correlation between the expressions of leptin and HIF-1α.
  
  
  METHODS
  A total of 120 male Sprague-Dawley rats were randomly divided into normal control group, silicosis model group, LP intervention groups (consisting of LP5, LP10 and LP20 groups according to the concentration of LP). The rats in the normal control group were intratracheally administered 1 mL normal sodium, and the ones in the other groups were intratracheally given 1 mL SiO₂(40 mg/mL) suspension. The rats in LP intervention groups were intraperitoneally injected with leptin 5, 10, 20 ng/kg.d respectively from the first day. Six rats in each group were sacrificed on the 7th, 14th, 21th and 28th day. The expression of LP on the 7th, 14th, 21th and 28th day and the hydroxyproline content on the 28th day in rat lung tissues were measured by ELISA, and the expressions of HIF-1α and LP proteins in the lung tissues of the silicosis model group were measured by Western blotting.
  
  
  RESULTS
  There were significant differences in the expression of LP in the lung tissues at each time point (7th, 14th, 21th and 28th day) among the five groups (F=669.18, 948.67, 1 172.00, 521.55, P<0.05). The LP content in the silicosis model group was significantly higher than that in the normal control group (P<0.05) and the expression of LP in the LP intervention groups were significantly elevated at each time point (P<0.05) as compared with the silicosis model group. Hydroxyproline content on 28th day was (0.89 ± 0.16), (3.14 ± 0.40), (3.78 ± 0.27), (4.35 ± 0.13), (4.87 ± 0.16) mg/g in normal control group, silicosis model group, LP5, LP10 and LP20 intervention groups, respectively. Compared with the normal control group, hydroxyproline content in the silicosis model group significantly increased (P<0.05), and compared with the silicosis model group, hydroxyproline content in LP intervention groups were significantly raised (P<0.05). The significant positive correlations were noted between the expressions of HIF-1α and LP (r=0.876, 0.796, 0.859 and 0.854 at each time, P<0.05).
  
  
  CONCLUSIONS
  The expression of LP goes up significantly in the lung tissues of rats with silicosis. Addition of exogenous leptin can increase the collagen deposition in the lung tissues; meanwhile leptin has a positive correlation with HIF-1α.
authors.affiliation: Department of Respiratory Medicine, Central Hospital of Datun Coal Company, Xuzhou 221611, China.
authors.forename: Houshuang
authors.initials: H
authors.lastname: Pei
authors.affiliation: Department of Respiratory Medicine, Central Hospital of Datun Coal Company, Xuzhou 221611, China.
authors.forename: Yongbin
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Respiratory Medicine, Central Hospital of Datun Coal Company, Xuzhou 221611, China.
authors.forename: Delong
authors.initials: D
authors.lastname: Fan
authors.affiliation: Department of Respiratory Medicine, Affiliated Hospital, Xuzhou Medical College, Xuzhou 221004, China.
authors.forename: Shuyang
authors.initials: S
authors.lastname: Zhu
authors.affiliation: Department of Respiratory Medicine, Affiliated Hospital, Xuzhou Medical College, Xuzhou 221004, China.
authors.forename: Maowei
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Xuzhou Mining Group General Hospital, Xuzhou 221004, China.
authors.forename: Huiting
authors.initials: H
authors.lastname: Li
authors.affiliation: Department of Respiratory Medicine, Affiliated Hospital, Xuzhou Medical College, Xuzhou 221004, China.
authors.forename: Bi
authors.initials: B
authors.lastname: Chen
authors.affiliation: Department of Respiratory Medicine, Affiliated Hospital, Xuzhou Medical College, Xuzhou 221004, China.
authors.forename: Miao
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Department of Respiratory Medicine, Affiliated Hospital, Xuzhou Medical College, Xuzhou 221004, China.
authors.forename: Ruijuan
authors.initials: R
authors.lastname: Zhou
mesh_terms: D000818:Animals; D015153:Blotting, Western; D003094:Collagen / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D006909:Hydroxyproline / Q000378:metabolism; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism*; D007274:Injections, Intraperitoneal; D020738:Leptin / Q000008:administration & dosage / Q000378:metabolism* / Q000494:pharmacology; D008168:Lung / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D008297:Male; D011658:Pulmonary Fibrosis / Q000378:metabolism* / Q000517:prevention & control; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012829:Silicosis / Q000378:metabolism* / Q000517:prevention & control; D013997:Time Factors
chemical_list: D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D020738:Leptin; D003094:Collagen; D006909:Hydroxyproline