Protective Effects And Mechanisms Of Taraxasterol On Alcoholic Liver Injury And Immunological Liver Injury In Mice

Taraxacum officinaleis a traditional Chinese medicine which has a long history in China.Taraxasterol is a pentacyclic-triterpene which was isolated from Taraxacum officinale as the main active ingredient.In the study,two models of ethanol-induced and concanavalin A-induced liver injury were established,the hepatoprotective effects and the mechanisms of Taraxasterol on alcoholic liver injury and immue liver injury in mice were studied,which provided scientific basis for the clinical application of Taraxasterol.The model of ethanol-induced alcoholic liver injury was established in mice.The mice were randomly divided into six groups:control group,EtOH group as model group,Tiopronin group as positive group,Taraxasterol high,medium and low dose groups(10,5,2.5 mg/kg).Each group of mice were treated intragastrically with drugs and 50%ethanol once a day for 15 days.12 h after the last ethanol administration,the blood and liver were collected from mice.The liver index was calculated.The levels of AST,ALT,TG,ADH and LDH in serum were detected.The activities of TG,MDA,GSH,SOD and ROS in liver tissue was measured.The content of TNF-α and IL-6 in serum was determined using ELISA kits.The expression of CYP2E1 protein in liver tissue of mice was detected by immunohistochemistry and Western blot,and the expression of Nrf2,HO-1,IκBα and p65 protein in liver tissue of mice was detected by Western blot method.The model of concanavalin A-induced immune liver injury was established in mice.The mice were randomly divided into six groups:control group,Com A group as model group,Bifondate group as positive group,Taraxasterol high,medium and low dose groups(10,5,2.5 mg/kg).Expect for the control group and Con A group,each group of mice were treated intragastrically with medicine once a day for 7 days.One hour after the last administration,the mice were injected via the tail vein with Con A(18 mg/kg).Eight hours later,the blood and liver were collected from mice.The liver index and spleen index were calculated.The levels of AST and ALT in serum were detected.The activities of MDA,GSH and SOD in liver tissue was measured.The content of TNF-α,IL-6,IL-1β,IFN-γ and IL-4 in serum was determined using ELISA kits.The apoptotic cells was detected in liver tissue using TUNEL kit.The expression of TLR2,TLR4,p65,Bax and Bcl-2 protein in liver tissue of mice was detected by Western blot method,and the value of Bax/Bcl-2 was calculated.Compared with EtOH group,Taraxasterol could significantly reduce the liver index,the levels of ALT,AST,TG,ADH and LDH in serum of mice,the content of TG,MDA and ROS in liver tissue of mice(P<0.05 or P<0.01),and significantly enhanced the activity of GSH and SOD in the liver tissue of mice(P<0.05 or P<0.01).Taraxasterol could significantly inhibit the secretion of TNF-a and IL-6 in serum(P<0.05 or P<0.01).Taraxasterol could significantly down-regulate the expression of CYP2E1 and p65 protein in mouse liver tissue,significantly inhibite the degradation of IκBα protein and significantly up-regulate the expression of Nrf2,HO-1 and IκBαin mouse liver tissue(P<0.05 or P<0.01).Compared with Con A group,Taraxasterol could significantly reduce the liver index and spleen index,the levels of ALT and AST in serum of mice,the content of MDA in liver tissue of mice(P<0.05 or P<0.01),and significantly enhanced the activity of GSH and SOD in the liver tissue of mice(P<0.05 or P<0.01).Taraxasterol could significantly inhibit the secretion of TNF-a,IL-6,IL-1β,IFN-γ and IL-4 in serum(P<0.05 or P<0.01).Taraxasterol could significantly down-regulate the expression of TLR2,TLR4 and p65 protein in liver tissue,and significantly decrease the value of Bax/Bcl-2.The results demonstrated that Taraxasterol could decrease the activity of enzymes such as AST and ALT,and increase the activity of antioxidant enzymes,reduce the occurrence of lipid peroxidation.Taraxasterol could regulate the critical factor IκBα and p65 protein expressions of NF-κB signaling pathway,upregulation of Nrf2 and antioxidant enzyme HO-1 to inhibit the production of oxidative stress,play its protective effects on ethanol and Con A-induced liver injury in mice.Taraxasterol could inhibit the secretion of cytokines,down-regulate the expression of NF-κB p65 and Bax protein,up-regulate the expression of Bcl-2 protein,reduce the damage caused by cytokines to hepatocytes and reduce the hepatocytes apoptosis,and play its protective effects on Con A-induced liver injury in mice.