Effect of dexamethasone on the content of pulmonary surfactant protein D in young rats with acute lung injury induced by lipopolysaccharide.
OBJECTIVE
Pulmonary surfactant protein-D (SP-D) is regarded as a valuable biomarker in acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). This study was to explore the changes of SP-D content in lung tissue following ALI and the effect of dexamethasone (Dex) on the SP-D content in young rats.


METHODS
One hundred and forty-four 21-day-old Sprague-Dawley rats were randomly assigned into control, ALI and Dex-treated groups. ALI was induced by intraperitoneal injection of lipopolysaccharide (LPS) (4 mg/kg) in the rats from the ALI and Dex-treated groups. Normal saline was given for the control group. Dex (5 mg/kg) was administered 1 hr after LPS injection in the Dex-treated group. At each time interval of 6, 12, 24, 36, 48 and 72 hrs after LPS injection, eight rats of each group were randomly chosen and sacrificed. Western blot was employed to detect the content of SP-D in lung tissues.


RESULTS
The pulmonary SP-D content decreased significantly at 36, 48 and 72 hrs after LPS administration in the ALI group, and reduced to a nadir (0.92 +/-0.11 vs 3.27 +/- 0.52) at 48 hrs compared with that of the control group (P < 0.01). The SP-D content in the Dex-treated group increased significantly at 36,48 and 72 hrs after LPS administration when compared with the ALI group (P < 0.01). A significant difference in the SP-D content between the Dex-treated and the control group was noted only at 72 hrs after LPS administration (P < 0.05).


CONCLUSIONS
The SP-D content in lung tissue was reduced following ALI in young rats at the early stage. Early administration of Dex can significantly increase the pulmonary SP-D content.
Shu
Lin-Hua
LH
Department of Pediatrics, Second Affiliated Hospital, China Medical University, Shenyang, China. shulinhua@126.com
Xue
Xin-Dong
XD
Shu
Lin-Hong
LH
Liu
Chun-Feng
CF
Han
Xiao-Hua
XH
Wu
Hong-Min
HM
Shang
Yun-Xiao
YX
Cai
Xu-Xu
XX
Wei
Ke-Lun
KL
D000818:Animals; D003907:Dexamethasone / Q000627:therapeutic use*; D008070:Lipopolysaccharides / Q000633:toxicity; D008168:Lung / Q000737:chemistry*; D037663:Pulmonary Surfactant-Associated Protein D / Q000032:analysis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012128:Respiratory Distress Syndrome / Q000188:drug therapy* / Q000378:metabolism
D008070:Lipopolysaccharides; D037663:Pulmonary Surfactant-Associated Protein D; D003907:Dexamethasone