Protective Effect Of Apigenin On D-GalN/LPS-induced Acute Liver Injury And Its Possible Mechanisms

Aim: To examine the protective effect of apigenin on D-galactosamine/ lipopolysaccharide(D-Gal N/LPS)-induced acute liver injury and its potential mechanisms.Methods: Male ICR mice were used in the vivo study.These mice were randomly divided into the control group,model group,apigenin 200 and 100 mg/kg groups,and silymarin 100 mg/kg group.The drug-treated mice were orally given apigenin or silymarin by gavage based on different doses for 7 days.After the last administration,the mice were intraperitoneally injected once with D-Gal N 700 mg/kg and LPS 20 ?g/kg to induce acute liver injury.After 6 h of D-Gal N/LPS treatment,all of these mice were sacrificed.Blood was collected to measure the serum alanine aminotransferase(ALT),aspartate aminotransferase(AST),total protein(TP),and albumin(ALB)levels.The liver was taken,the coefficient of liver weight was calculated,the hepatic histopathological changes were examined under a light microscope,the hepatic superoxide dismutase(SOD),catalase(CAT),glutathione-S-transferase(GST),glutathione peroxidase(GSH-Px),glutathione reductase(GR),malondialdehyde(MDA),reduced glutathione(GSH),and tumor necrosis factor-alpha(TNF-?)levels were determined.The expressions of hepatic nuclear factor erythroid 2-related factor 2(Nrf-2),peroxisome proliferator-activated receptor ?(PPAR?),and nuclear factor kappa B(NF-?B)proteins were determined by Western Blot methods,respectively.The rat BRL hepatocytes were used to observe the effects of apigenin on D-Gal N/LPS-induced hepatocellular injury in vitro.The levels of the supernatant ALT,AST,TNF-?,MDA,SOD,and CAT were determined.The expression levels of hepatocellular Nrf-2,PPAR?,NF-?B,and inhibitor of kappa B-alpha(I?B-?)proteins were determined by Western Blot methods,respectively.The inhibitors of PPAR? and Nrf-2 were used to observe the variations in the effects of apigenin on expressions of PPAR? and Nrf-2 proteins,and to illustrate the exact protective mechanisms of apigenin against D-Gal N/LPS-induced hepatic injury.Results: The animal experimental results showed that after administration of apigenin 100-200 mg/kg for 7 days,the hepatic necrosis and inflammatory cell infiltration were significantly ameliorated,the levels of serum ALT and AST were decreased,while the levels of serum TP,ALB,and GLB were increased,especially in the apigenin 200 mg/kg group(P<0.05).Also,the contents of hepatic TNF-? and MDA were obviously decreased(P<0.01 or P<0.05),and the levels of hepatic SOD,CAT,GST,and GR were obviously increased(P<0.01 or P<0.05).The Western Blot assays showed that apigenin treatment could significantly increase the protein expressions of hepatic Nrf-2 and PPAR?(P<0.01 or P<0.05),and decrease the expression of hepatic NF-?B proteion(P<0.01).In vitro,the results showed that following pretreatment of hepatocytes with apigenin,the levels of supernatant ALT,AST,TNF-?,and MDA were decreased significantly(P<0.01 or P<0.05),while the levels of supernatant SOD and CAT were increased significantly(P<0.01 or P<0.05).The levels of hepatocellular Nrf-2,PPAR?,and I?B-? proteins were increased(P<0.01 or P<0.05),and the expression of NF-?B protein was significantly decreased(P<0.01).After pretreatment of hepatocytes with the inhibitor of PPAR? GW9662,apigenin could increased the expression of hepatocellular Nrf-2 protein yet(P<0.01).But the increment of PPAR? protein expression and decrement of NF-?B protein expression by apigenin were completely cancelled after pretreatment of hepatocytes with the inhibitor of Nrf-2 BML-111.Conclusion: Apigenin had a protective effect on D-Gal N/LPS-induced acute liver injury,and its mechanisms might be associated with the enhancement of nucleus Nrf-2 protein,which subsequently increased the expressions of antioxidative gene proteins and inhibited the NF-?B inflammatory pathway via increment of Nrf-2-mediated PPAR? protein expression.