The Protective Effects And Mechanisms Of Imperatorin On Acute Respiratory Distress Syndrome Of Mice

Objectives: 1.To research whether imperatorin plays a protective role on lipopolysaccharide-induced acute respiratory distress syndrome(ARDS)in mice and investigate its possible mechanisms.2.To observe the effect of different doses of imperatorin on lipopolysaccharide-induced ARDS in mice.Methods: Thirty-two female BALB/c mice were randomly divided into four groups: normal control group(Control group),model group(LPS group),imperatorin 30mg/kg group(LPS+ IMP 30mg/kg group),imperatorin 60mg/kg group(LPS+IMP 60mg/kg group).Mice in imperatorin groups were intraperitoneally injected with imperatorin and mice in Control group and LPS group were intraperitoneally injected with 4% dimethyl sulfoxide solution.After an hour,mice in model group and imperatorin groups were intranasally instilled with lipopolysaccharide and mice in normal control group were intranasally instilled with corresponding volume of phosphate buffer salt solution(PBS).The lung tissue of each group was collected after 7 hours of lipopolysaccharide modeled.The wet-to-dry ratio of lung was measured.Using hematoxylin-eosin(HE)staining to observe the pathological changes of lung tissue in mice.Lung tissue injury score was calculated.The myeloperoxidase(MPO)activity and the reactive oxygen species(ROS)level in lung tissue in mice were measured.The levels of tumor necrosis factor-?(TNF-?)and interleukin-1?(IL-1?)in lung tissue in mice were detected by enzyme-linked immunosorbent assay(ELISA).The expression levels of phosphorylated phosphatidylinositol 3'-kinase(p-PI3-K),phosphorylated protein kinase B(p-Akt),phosphorylated nuclear factor ?B(p-NF-?B)p65,phosphatidylinositol 3'-kinase(PI3K),protein kinase B(Akt),nuclear factor ?B(NF-?B)p65 and matrix metalloproteinase 9(MMP9)in lung tissues in mice were detected by western blot(WB).Results: 1.According to the detection of wet-to-dry ratio of lung,the wet-to-dry ratio of lung in LPS group was higher than that in Control group(P<0.05).The wet-to-dry ratio of lung in LPS+IMP 60 mg/kg group was higher than that in Control group,which was not statistically significant(P>0.05).The wet-to-dry ratio of lung in both LPS+IMP 30mg/kg group and LPS+IMP 60mg/kg group was lower than that in LPS group(P<0.05)but that in LPS+IMP 60mg/kg group was lower than that in LPS+IMP 30mg/kg group(P<0.05).2.HE staining revealed normal lung tissue structure in Control group.LPS group showed that lung tissue structure destroyed,alveolar septum thickened,edema,congestion and inflammatory cell infiltration in lung tissue,alveolar cavity decreased.The above histology changes of LPS+IMP 30mg/kg group and LPS+IMP 60mg/kg group were lighter than those in LPS group,while those in LPS+IMP 60mg/kg group were lighter than those in LPS+IMP 30mg/kg group.The lung tissue injury score of LPS group is higher than that of Control group(P<0.05).The lung injury score of both LPS+IMP 30mg/kg group and LPS+IMP 60mg/kg group was lower than that of LPS group(P<0.05),while that of LPS+IMP 60mg/kg group was lower than that of LPS+IMP 30mg/kg group(P<0.05).3.The ROS level and MPO activity in LPS group were increased compared with Control group(P<0.05).The MPO activity in LPS+IMP 60mg/kg was increased compared with Control group,which is not statistically significant(P>0.05).The ROS level in both LPS+IMP 30 mg/kg group and LPS+ IMP 60mg/kg group was decreased compared with LPS group(P<0.05).The MPO activity in LPS+IMP 30 mg/kg group was decreased compared with LPS group(P>0.05).The MPO activity in LPS+IMP 60 mg/kg group was decreased compared with LPS group(P<0.05).The ROS level and MPO activity in LPS+IMP 60 mg/kg group were decreased compared with LPS+IMP 30mg/kg group(P<0.05).4.ELISA analysis showed that the levels of TNF-? and IL-1? in LPS group were increased compared with Control group(P<0.05).The levels of TNF-? and IL-1? in both LPS+IMP 30mg/kg group and LPS+IMP 60mg/kg group were decreased compared with LPS group(P<0.05).The level of IL-1? in LPS+IMP 60 mg/kg group were decreased compared with LPS+IMP 30mg/kg group(P>0.05).The level of TNF-? in LPS+IMP 60 mg/kg group were decreased compared with LPS+IMP 30mg/kg group(P<0.05).5.Western Blot analysis showed that the expression levels of p-PI3 K,p-Akt,p-NF-?B p65 and MMP9 in LPS group were increased compared with Control group(P<0.05).Those in LPS+IMP 60 mg/kg group were increased compared with Control group(P>0.05),while those in both LPS+IMP 30 mg/kg group and LPS+IMP 60 mg/kg group were decreased compared with LPS group(P<0.05).Those in LPS+IMP 60 mg/kg group were decreased compared with LPS+IMP 30mg/kg group(P<0.05).Conclusions: 1.Imperatorin has protective effect on lipopolysaccharide-induced ARDS in mice.2.The protective effect of imperatorin may be related to its influence on the activity of ROS mediated PI3 K /Akt/NF-?B signaling pathway,down-regulation of the expression levels of p-PI3 K,p-AKT and pNF-?B p65 proteins,and ultimately reduction of the release of pro-inflammatory factors.3.The protective effect of imperatorin in high dose group was better than that in low dose group.