Study On The Effect And Mechanism Of Glycyrrhetic Acid On The Treatment Of Acute Radiation-induced Lung Injury

Purpose: By establishing acute radiation-induced lung injury model in mice toobserve the effect of glycyrrhetinic acid on pathomorphism changes and expression ofSmad2, Smad3, TGF-β1in these models’ lung and to explore its possiblemechanism.Materials and Methods:90adult C57BL/6female mice were randomly dividedinto four groups:(1) control group (Conrol group): no irradiation;(2) glycyrrhetinicgroup (GA group): irradiation+glycyrrhetinic acid40mg/kg by gavage;(3)irradiation group (IR group): irradiation+saline0.01ml/g by gavage. The mice’swhole lung in irradiation group were exposed to12Gy6MV-X ray once. Irradiationstart the day administered once daily for7days, then changed every other day untilone month after irradiation.At the end of the2nd,17th and30th day, chose9-10micerandomly from every group to be executed. Histopathological study of lung tissue wasdone with HE and Masson staining.The expression of Smad2,Smad3and TGF-β1inlung tissue were assessed by immunohist-ochemical staining and real time-PCR.Results:1. Pathological HE and Masson staining: each time point after irradiation,the degree of alveolitis in irradiation group were significantly higher than the controlgroup and GA group, the differences were statistically significant (P <0.05).17th day,30th day after irradiation, collagen deposition increased in IR group, with the controlgroup, GA group differences were statistically significant (P <0.05).2. Immunohistochemical staining results: compared with the control group, the IRgroup of the2nd,17th day after irradiation, the expression of the Smad2, Smad3and TGF-β1in lung tissue progressive increased (P<0.05).After giving glycyrrhetinicacid intervention, the content of TGF-β1, Smad2, Smad3significantly reduced, therewas a significant difference between the two group(P <0.05). 3. Real time-PCR results: compared with the control group, the IR group of the2nd,17th,day after irradiation，the expression of the Smad2, Smad3and TGF-β1inlung tissue progressive increased (P<0.05).After giving glycyrrhetinic acidintervention, the content of TGF-β1, Smad2, Smad3significantly reduced, there was asignificant difference between the two group(P <0.05).Conclusions:: Glycyrrhetinic acid can reduce the degree of acute radiation-inducedlung injury in mice, reducing TGF-β1, smad2, smad3expression levels, itsmechanism of anti-radiation-induced lung injury may by decreasing expression ofTGF-β1and inhibit TGFβ1/Smad signal transduction pathway.