RESUMEN
ObjectiveTo investigate the effects and mechanism of baicalin （BA） on lipopolysaccharide （LPS）-induced acute lung injury in rats. MethodEighty healthy male SD rats were randomly divided into the control group， model group， low-dose BA （BA-L） group， medium-dose BA （BA-M） group， high-dose BA （BA-H） group， dexamethasone （DEX） group， SB203580 group， and BA + SB203580 group， with 10 rats in each group. The rats in the BA-L， BA-M， and BA-H groups were injected intraperitoneally with different doses （10， 50， 100 mg·kg-1） of BA solution， the ones in the DEX group with 5 mg·kg-1 DEX solution， the ones in the SB203580 group with 0.5 mg·kg-1 SB203580 solution， the ones in the BA + SB203580 group with 100 mg·kg-1 BA solution and 0.5 mg·kg-1 SB203580， and those in both the control group and model group with the same volume of normal saline， once per day， for seven successive days. One hour after the last administration， rats in all groups except for the control group were given 5 mg·kg-1 LPS via intratracheal instillation for inducing the acute lung injury， whereas those in the control group received the same volume of normal saline solution. Twelve hours later， the lung tissues were sampled and stained with htoxylin-eosin （HE） for observing the pathological changes， followed by the counting of the total number of cells and neutrophils in bronchoalveolar lavage fluid （BALF）. The wet/dry weight ratio of the lung tissue and the contents of serum superoxide dismutase （SOD） and malondialdehyde （MDA） were measured. The activity of reactive oxygen species （ROS） in the lung tissue was detected by immunofluorescence and the levels of interleukin-1β （IL-1β）， interleukin-18 （IL-18）， interleukin-6 （IL-6）， and tumor necrosis factor-α （TNF-α） in BALF by enzyme-linked immunosorbent assay （ELISA）. Immunohistochemistry （IHC） was conducted to determine the relative expression of p-p38 mitogen-activated protein kinase （MAPK） and Western blotting was carried out to detect the protein expression levels of p-p38 MAPK， thioredoxin interacting protein （TXNIP）， NOD-like receptor protein 3 （NLRP3）， and cysteinyl aspartate specific protease-1 （Caspase-1） in the lung tissue. ResultCompared with the control group， the model group displayed inflammatory pathological changes in lung tissue， elevated wet/dry weight ratio， total number of cells and neutrophils in BALF， and ROS and MDA levels （P<0.01）， decreased SOD activity （P<0.01）， and up-regulated IL-1， IL-18， IL-6， TNF-α， p-p38 MAPK， NLRP3， and Caspase-1 expression （P<0.01）. Compared with the model group， BA at different doses， SB203580， and BA + SB203580 all effectively alleviated the pathological changes in lung tissue induced by LPS， reduce the lung wet/dry weight ratio， the total number of cells and neutrophils in BALF， and ROS and MDA levels （P<0.05，P<0.01）， enhanced the activity of SOD （P<0.05，P<0.01）， and down-regulated the expression of IL-1β， IL-18， IL-6，TNF-α， p-p38 MAPK， NLRP3， and Caspase-1 in lung tissue （P<0.05，P<0.01）. ConclusionBA has a protective effect against LPS-induced acute lung injury， which may be related to its inhibition of p38MAPK/NLRP3 signaling pathway and the improvement of inflammatory response.