[Regulatory effect of signal transducer and activator of transcription 1 on acute lung injury induced by endotoxin in rat].

Objective: To investigate the expression and regulatory effect of signal transducer and activator of transcription 1 (STAT1) in acute lung injury (ALI) induced by endotoxin.

Methods: ALI model was induced by intravenous lipopolysaccharide (LPS). Wistar rats were randomly divided into three groups, the control group, LPS group, dexamethasone (DEX) group. Each group was subdivided into five subgroups according to the time after administration of endotoxin (1, 2, 4, 8 and 16 hours), except the control group. Rats were given normal saline by gavage in control group and LPS group, and 0.135 mg/kg DEX in DEX group for 5 days. Six rats were sacrificed at different time points after normal saline or LPS injection. The lungs were harvested for microscopic examination. Western blotting was used to examine protein expression of STAT1 in lung tissue.

Results: In LPS group the levels of STAT1 began to increase at 1 hour, reaching the peak value at 4 hours, then declined gradually. There was a significant difference at 2, 4, 8 hours (all P<0.01). The expression trend for STAT1 was similar between DEX and LPS groups, but the levels of STAT1 were significantly decreased in DEX group at 2, 4, 8 hours compared with the LPS group (all P<0.05).

Conclusion: There is abnormal expression of STAT1 in the lung tissue of ALI. The abnormal STAT1 expression takes part in the inflammatory formation of lung tissue in ALI.