Protective Effect And Mechanism Of Glabridin On Lipopolysaccharide Induced Lung Injury In Rats

Objective To investigate the effect of Glabridin(GLA)on pulmonary edema and pathological changes in lung tissue of normal rats and acute lung injury(ALI)rats induced by lipopolysaccharide(LPS).Methods Ninety-six Wistar rats were randomly assigned into control group(Control 6h?12h?24h),GLA alone group(GLA group)(GLA6h?12h?24h),model group(LPS 6h?12h?24h)?,GLAtreatment group(LPS+GLA6h?12h?24h),with 8 in each group.The rats in GLA group were gavaged only by glabridin(30mg/kg),GLA treatment group was given GLA after intraperitoneal injection of LPS for 1 h(30mg/kg);The rats in the control group received an equal volume of normal saline at the same times,Rats in each group were given biopsy of lung tissue at 6h,12h and 24h after dosing.Measuring the wet weight and dry weight and calculating the wet/dry(W/D)ratio of lung tissue;Lung tissue was subjected to HE staining,and the pathological changes of lung tissue were observed under light microscope?Results 1.Compared with the control group,the wet/dry weight ratio of the lung tissue was increased in the model group(P<0.05),and the change was most obvious in the 12h group,which indicated that the pulmonary edema was the most obvious at this time;The lung/dry weight ratio of GLA treatment group was lower than that of model group(P<0.05);There was no significant difference between GLA alone group and control group.2.Observed the control group and GLA alone group under light microscope,we can find that the lung tissue was intact,the alveolar wall had no congestion,the alveolar cavity was clear and the pulmonary interstitial without infiltration of inflammatory cells;while,we can discover that the alveolar wall diffuse thickened,some alveolar wall was damaged,there were obvious inflammatory cell infiltration,alveolar hemorrhage and structural damage in the model group;The pathological changes of GLA treatment group were significantly less than that of model group.Conclusion 1.The rat model of acute lung injury was successfully prepared by intraperitoneal injection of lipopolysaccharide;2.Glabridin has the effect of reducing the pulmonary edema caused by lipopolysaccharide and pathological changes of lung tissue;3.Glabridin had no adverse effects on pulmonary edema and pathological changes of lung tissue in normal rats.Objective To explore the mechanism of glabridin by anti-inflammatory and anti-oxidative effects in alleviating acute lung injury induced by lipopolysaccharide in rats.Methods Ninety-six Wistar rats were randomly assigned into control group(Control 6h?12h?24h),model group(LPS 6h?12h?24h),GLA treatment group(LPS+GLA 6h?12h?24h),Ulinastatin treatment group(LPS+UTI 6h?12h‘'24h),with 8 in each group.Acute lung injury rat model was reproduced by intraperitoneal injection of LPS(10mg/kg),GLA treatment group was given GLA after intraperitoneal injection of LPS for 1 h(30mg/kg),UTI treatment group was injected intraperitoneally with ulinastatin on the right side,one hour later of intraperitoneal injection of LPS on the left side(20000u/kg);The rats in the control group received an equal volume of normal saline at the same time.Plasma and lung tissue samples were collected at different time points in each group.Detecting the levels of tumor necrosis factor-a,interleukin-18,pulmonary surfactant A in plasma,and the contents of superoxide dismutase,malondialdehyde and nitric oxide in lung homogenate.Results 1.Compared with the control group,the levels of TNF-a and IL-18 in the model group were significantly higher than those in the control group(P<0.05).GLA and UTI can inhibit the increase of TNF-a and IL-18,and effect of glabridin is better than UTI.2.Compared with the control group,the plasma SP-A level in the model group was higher than that in the control group at 12h and 24h group,but there was no significant difference between the 6h group(P>0.05);It means that GLA and UTI can inhibit the increase of SP-A caused by lipopolysaccharide,the inhibitory effect between GLA and UTI was no significant difference(P>0.05)3.Compared with the control group,the content of MDA increased significantly in the lung tissue of the model group(P<0.05);Compared with model group,the levels of MDA in lung tissue were significantly lower than those in GLA treatment group and UTI treatment group(P<0.05).There was no significant difference between GLA treatment group and UTI treatment group.4.Compared with the control group,there was no significant difference in the NO content of the lung tissue in the 6h group in the control group,but the NO content in the 12h and 24h groups increased significantly(P<0.05);The content of NO in lung tissue of GLA treatment group was lower than that of model group,and the difference was significant between 12h group(P<0.05),while 6h and 24h group was not statistically significant(P>0.05);Compared with the model group,the content of NO in lung tissue in ulinastatin treatment group was decreased,but there was significant difference between 12h group(P<0.05),yet 6h and 24h group was not statistically significant(P>0.05);Compared with GLA treatment group and control group,the content of NO in UTI treatment group was significantly increased,and the difference was statistically significant(P<0.05)?GLA inhibits NO effect better than UTI.5.Compared with the control group,the SOD content in the lung tissue was significantly decreased in the model group(P<0.05);The content of SOD in lung tissue of GLA treatment group was significantly higher than that of model group(P<0.05);Compared with the UTI treatment group the content of SOD in lung tissue was higher than that of model group,but the difference was not statistically significant(P>0.05).The level of SOD in the lung tissue of GLA group was significantly higher than that of ulinastatin group,and the difference was statistically significant(P<0.05),suggesting that GLA could significantly increase the SOD content of lung tissue in rats with acute lung injury,and the effect was better than that of ulinastatin.Conclusion 1.GLA exert protective effect on lipopolysaccharide-induced lung injury in rats by inhibiting inflammatory factors to reduce inflammation.2.GLA exert protective effect on lipopolysaccharide-induced lung injury in rats by scavenging oxygen free radicals,regulating oxidation/antioxidant balance.3.GLA can improve the surface tension and permeability of alveoli by regulating the content of pulmonary surfactant,which exert protective effect on lipopolysaccharide-induced lung injury in rats?Objective To investigate the role and the mechanism of p38MAPK/ERK signaling pathway in lipopolysaccharide-induced acute lung injury,and how the glabridin exerts a protective effect on the inhibition of p38MAPK/ERK signaling pathway.Methods Eighty Wistar rats were randomly assigned into control group.model group(LPS 6h?12h?24h).GLA treatment group(LPS+GLA 6h?12h?24h),UTI treatment group(LPS+UTI 6h?12h?24h),with 8 in each group.Acute lung injury rat model was reproduced by intraperitoneal injection of LPS(10mg/kg),GLA treatment group was given GLA after intraperitoneal injection of LPS for 1 h(30mg/kg),UTI treatment group was injected intraperitoneally with ulinastatin on the right side after 1 hour of intraperitoneal injection of LPS on the left side(20000u/kg);The rats in the control group received an equal volume of normal saline at the same times,and rats in each group were given biopsy of lung tissue at 6h,12h and 24h after dosing.p38 mitogen activated protein kinase(p-p38MAPK)and phosphorylated extracellular regulated protein kinases(pERK)protein in lung tissue were detect by Immunohistochemical method and Western blot method.Results 1.Immunohistochemical results of p-p38MAPK:The p-p38MAPK positive signal in the nucleus of the lung tissue of the control group was very weak?The positive expression of p-p38MAPK in the model group was significantly increased,which was mainly distributed in infiltrating inflammatory cells,airway epithelial cells,alveolar epithelial cells and vascular endothelial cells,and no significant difference in cytoplasmic expression,but nuclear expression was significantly enhanced:The distribution of p-p38MAPK positive cells in GLA group and UTI group was similar to that in model group,but the number of positive cells was significantly decreased and the signal was significantly lower than that of model group.2.Immunohistochemical results of p-ERK:The expression of p-ERK in the cytoplasm of the control group was very weak and scattered in the cytoplasm of airway epithelial cells and alveolar epithelial cells;In the model group,phosphorylated ERK-positive cells were expressed in the cytoplasm and nucleus of inflammatory cells,airway epithelial cells,alveolar epithelial cells and vascular endothelial cells;The expression of cytoplasmic positive cells and positive cells in GLA treatment group and UTI treatment group was significantly lower than that in model group.3.Western-blot of p-p38MAPK:The expression of p-p38MAPK in the model group was significantly increased compared with the control group,the difference was statistically significant(P<0.05);GLA treatment group can significantly inhibit the phosphorylation of p38MAPK induced by lipopolysaccharide,and its inhibition is stronger than that of UTI traetment group;while there was no significant difference in the expression of p38MAPK between each group.4.Western blot results of pERK(Figure 3-4):The expression of ERK and pERK in the lung of the model group was significantly higher than that in the control group,and the difference was statistically significant(P<0.05),as well as GLA group can significantly inhibit lipopolysaccharide-induced ERK and its phosphorylation,but its inhibition is slightly weaker than UTI.Conclusion GLA protects against lung injury induced by lipopolysaccharide by inhibiting p38MAPK/ERK signaling pathway.