Establishment of Acute Lung Injury Model Induced by Intraperitoneal Injection of Lipopolysaccharide in Rats

The model of acute lung injury （ALI） was established by intraperitoneal administration,but there was no time-point observation and comparison.ALI model was established by intraperitoneal injection of lipopolysaccharide （LPS） at the concentration of 10 mg·kg^-1 (10 mg LPS dissolved in 1 mL normal saline to prepare 1 mL·kg^-1 solution) in rats.The control group （CG） was intraperitoneally injected with saline of the same dose.In the LPS group,lung tissues were collected at 4,6,8,12 and 24 h after administration.Then,the morphology changes,the ratio of wet-to-dry weight （W/D）,the expression of interleukin-1β （IL-1β） and tumor necrosis factor-α （TNF-α） proteins,the levels of malondialdehyde （MDA）,the activities of superoxide dismutase （SOD）,glutathione peroxidase （GSH） were measured.To verify the success of the model,the degrees of lung injury via Western blot,RT-PCR,ELISA and other techniques were detected at different time points,and the severe time of the ALI model established was deterimined by intraperitoneal administration,which provided a stable model basis for the study of the pathogenesis of ALI in the future.The results showed that the lung injury occurred in LPS group.W/D and lung pathological changes at 12 and 24 h of LPS group were significantly different from those in the CG.Compared with the CG,the expression of IL-1β and TNF-α proteins and the content of MDA in lung tissues of LPS group increased and most significant difference was found at 12 and 24 h （p＜0.01）.Compared with the CG,the activities of SOD and GSH in LPS 12 h group decreased significantly （p＜0.01）.In conclusion,inflammation and oxidative damage were the main causes of the ALI in rats.Lung injury was most obvious 12 h after intraperitoneal injection of 10 mg·kg^-1 LPS.