Protective Effect Of Baicalin Magnesium Salt On LPS-induced Acute Lung Injury In Mice

Objectives:To select a mice model of acute lung injury(ALI)using lipopolysaccharide(LPS),to observe whether Baicalin magnesium salt(BA-Mg)has a protective effect on ALI mice,to compare the difference of efficacy of BA-Mg,Baicalin(BA)and MgSO4 on ALI,and to preliminarily explore BA-Mg’s therapeutic mechanism provides theoretical and experimental basis for the research and development of drugs for the treatment of ALI,and to lay a foundation for further study of the mechanism of action of BA-Mg.Methods:Thirty-five male ICR mice were randomly divided into 7 groups with 5 mice in each group.Specifically,the control group,model group,BA-Mg low-dose group(100 mg/kg),BA-Mg high-dose group(200 mg/kg),BA group(195.2 mg/kg),MgSO4 group(5.2 mg/kg),dexamethasone group(5 mg/kg).Doses of BA and MgSO4 were converted according to equal molar doses of BA and Mg2+in the high-dose BA-Mg group,respectively.ALI model was established by nasal dripping of LPS(16 mg/mL)in model group and administration group,the control group was given the same volume of normal saline;BA-Mg different dose groups,BA group and MgSO4 group were administered by intraperitoneal injection once a day 3 days before the start of the experiment,and LPS(16 mg/mL)was instilled into the nasal cavity on the 4th day to establish an ALI model,re-administered 1h after modeling on the 4th day,then continuously dosing for 2 days,a total of 6 dosing.In the dexamethasone group,an equal volume of normal saline was injected into the abdominal cavity on the first 3 days,re-administered 1h after modeling on the 4th day,and then administered for 2 consecutive days for a total of 3 times.The control group and the model group were given an equal volume of sterile water for injection by intraperitoneal injection,the dosing volume is 0.1 mL/10 g.Anesthetizing the mice 1 hour after the end of the administration,and taking the lung tissue and bronchoalveolar lavage fluid of the mice after execution;Calculating the wet/dry weight(W/D)ratio of lung tissue;Calculating the total cells,neutrophils,and macrophages in BALF;Enzyme-linked immunoadsorbent assay(ELISA)detects the contents of tumor necrosis factor-α(TNF-α),interleukin-1 β(IL-1 β)and IL-6 in BALF;Detection of Myeloperoxidase(MPO),superoxide dismutase(SOD)and malonaldehyde(MDA)in homogenate of lung tissue by ELISA;Pathological staining and hematoxylin-eosin staining(HE)were performed to observe the pathological changes of the lung tissue of mice in each group,and pathological staining was performed to score;Protein levels of Toll-like receptor 4(TLR4),Myeloid differentiation primary response 88(MyD88),Nuclear factor-κB p65(NF-κB p65)and phosphorylated NF-κB p65 were detected by Western blot assay.Results:Mice in the model group were sluggish,with towering and dim hairs,and reduced activity levels.After sampling,the W/D ratio of lung tissue was significantly increased,inflammatory cells in the lungs increased,and inflammatory factors were released in large quantities.The pathological section of lung tissue showes obvious neutrophils infiltration,thickening of alveolar wall,disorder of lung tissue structure,destruction of alveolar structure,etc;The contents of MDA content in lung tissues increased significantly,MPO activity increased,SOD activity decreased significantly;TLR4,MyD88,and p-p65/p65 protein levels were significantly expressed.Each administration group improved the state of LPS-induced mice to varying degrees,and compared with BA and MgSO4,the BA-Mg high-dose group was more effective in reducing the lung wet/dry weight ratio,reducing inflammatory cell activation and mass aggregation,and reducing inflammation cells release a large number of inflammatory factors,reduce lung tissue MDA content,inhibit MPO activity,and increase SOD activity,and significantly down-regulate the expression of TLR4,MyD88,and p-p65/p65 protein levels.Conclusions:1.After LPS was instilled into the nasal cavity,the physiological and biochemical indexes of the mice were consistent with the characteristics of ALI,and the mice ALI model was successfully replicated.2.BA-Mg can significantly antagonize LPS-induced ALI lesions in mice,and have better anti-inflammatory and antioxidant capacity than equimolar doses of BA and MgSO4.3.The mechanism of BA-Mg’s protection of ALI may be related to the inhibition of inflammatory signal TLR4/MyD88/NF-κB protein activation.