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^-1solution)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-1βand TNF-αproteins 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.