Effect Of Carbachol On Acute Lung Injury Induced By Hyperoxia In Mice

Objective:1.To detect the expression changes of inflammatory factors in hyperoxia-induced acute lung injury（HALI）in mice.2.To observe the effect of carbachol（Carba）on the TLR4/NF-κB signaling pathway.3.To determine whether Carba can alleviate lung injury and its mechanism in HALI mice,and provide theoretical basis for HALI prevention and treatment.Methods:Thirty-two healthy male ICR mice were randomly divided into four groups:control group,hyperoxia exposure three days group（HO₂3d group）,hyperoxia exposure three days+Carbachol group（HO₂3d+Carba group）,and Carbachol group（Carba group）,eight mice in each group.The general view of the lungs was observed with naked eyes,and the pathological changes of lung tissue in each group were observed under light microscope after the models were completed in each group.The expression of TLR4 and NF-κB protein were detected by Western blot method.And the expression of HMGB-1 and TNF-αmRNA in lung tissues were detected by RT-PCR.Results:There was no significant difference in the detection indexes between the Carba group and the Control group（P>0.05）;The naked eyes of the lungs were fresh and tender,and there was no bleeding point;Under the light microscope,the alveolar structure was intact and no obvious abnormal changes were observed.The surface of lung tissue of HO₂3d group had obvious hemorrhage,display under light microscope showing pulmonary interstitial edema,inflammatory cell infiltration,and severe destruction of lung tissue structure;At the same time,the expression of TLR4,NF-κB protein and HMGB-1 and TNF-αmRNA were especially higher than those in the control group and Carba group（P<0.01）.The degree of lung tissue damage in the HO₂3d+Carba group was attenuate in contrast to the HO₂3d group,and the expression of TLR4,NF-κB protein and HMGB-1and TNF-αmRNA were significantly lower than HO₂3d group（P<0.01）.Conclusion:Hyperoxia exposure can increase the expression of TLR4 and NF-κB in lung tissue,and cause inflammatory injury in lung tissue.Intervention of HALI with carbachol can significantly reduce the release of inflammatory cytokines such as HMGB-1 and TNF-α,and reduce the degree of lung injury.The mechanism is related to the inhibition of TLR4/NF-κB signaling pathway,which has a protective effect on HALI.