Antagonistic Effect Of Lycopene On Liver Injury Induced By Nano Titanium Dioxide In Mice

Objective:Nano titanium dioxide（Nano-Ti O₂）can induce hepatotoxicity through oxidative stress reaction because of its unique physical and chemical properties.Lycopene,as a natural antioxidant,has been proved to alleviate oxidative damage induced by many exogenous substances.The purpose of this study was to explore whether lycopene could alleviate liver injury induced by Nano-Ti O₂in mice,and to investigate the mechanism of lycopene in alleviating liver injury from oxidative damage and apoptosis,which would provide a theoretical foundation for the prevention and treatment of liver injury caused by Nano-Ti O₂and the application of lycopene.Methods:96 healthy male ICR mice were randomly divided into 8 groups:control group,Nano-Ti O₂group（50 mg/kg BW）,different doses of lycopene group（5,20 and 40 mg/kg BW,respectively）and Nano-Ti O₂combined with different doses of lycopene group（50 mg/kg BW for Nano-Ti O₂,and 5,20 and 40 mg/kg BW for lycopene）.After intragastric administration for 30 days,the mice were killed through cervical dislocation.The livers of mice were taken to observe the pathological changes.The levels of ALT,AST and ALP in plasma of mice were detected using commercial kit;the contents of MDA and GSH,the activity of SOD,the level of GSH-Px and T-AOC in livers of mice were measured using commercial kits.The apoptosis of hepatocytes was detected using TUNEL staining,and the expression of apoptosis-related proteins was detected through western blotting.Results:1.The liver morphology of mice in the control group and all different doses of lycopene groups were normal.In the Nano-Ti O₂group,the structure of hepatic lobules of mice was blurred,the arrangement of hepatocytes were disordered,lipid vacuoles were formed within hepatocytes,some hepatocytes were necrosed,and appeared inflammatory cell infiltration.Compared with that of the Nano-Ti O₂group,the pathological changes such as liver hyperemia and lipid vacuoles were fewer in livers of mice in the Nano-Ti O₂+5,20 and 40 mg/kg BW lycopene groups.Compared with those of the control group,the levels of ALT,AST and ALP in plasma of mice in Nano-Ti O₂group were significantly increased（P<0.05）,the levels of ALT and AST in plasma of mice in the 20 mg/kg BW lycopene group were obviously decreased（P<0.05）,the plasma ALP level of mice in 5,20 and 40 mg/kg BW lycopene groups was obviously decreased（P<0.05）.Compared with those of the Nano-Ti O₂group,the levels of ALT and AST in plasma of mice in the Nano-Ti O₂+5,20 and 40 mg/kg BW lycopene groups were significantly decreased（P<0.05）,and the level of ALP in plasma of mice in Nano-Ti O₂+20 and 40 mg/kg BW lycopene groups were significantly decreased（P<0.05）.2.Compared with those of control group,the activity of GSH-Px and SOD,the content of GSH and the level of T-AOC in livers of mice in the Nano-Ti O₂group were significantly decreased（P<0.05）,while the level of MDA was significantly increased（P<0.05）,the SOD activity and GSH content in livers of mice in all different doses of lycopene groups were significantly increased（P<0.05）,the GSH-Px activity in livers of mice in 5 and 20 mg/kg BW lycopene groups was significantly increased（P<0.05）,the T-AOC level in livers of mice in 20 and 40 mg/kg BW lycopene groups were significantly increased（P<0.05）,the MDA level in livers of mice in 20 and 40 mg/kg BW lycopene groups was significantly decreased（P<0.05）.Compared with those of the Nano-Ti O₂group,the SOD activity and GSH content in livers of mice in the Nano-Ti O₂+5,20 and 40 mg/kg BW lycopene groups were significantly increased（P<0.05）,the GSH-Px activity in livers of mice in the Nano-Ti O₂+5 and 20 mg/kg BW lycopene groups were significantly increased（P<0.05）,and the T-AOC level in livers of mice in Nano-Ti O₂+20 and 40 mg/kg BW lycopene groups were significantly increased（P<0.05）,the MDA level were decreased significantly in livers of mice in the Nano-Ti O₂+20 and 40 mg/kg BW lycopene groups（P<0.05）.3.No obvious apoptotic cells were observed in liver of mice in control group and different doses of lycopene groups.There were more apoptotic cells observed in livers of mice in the Nano-Ti O₂group.Compared with that of the Nano-Ti O₂group,the number of apoptotic cells in livers were observed decreased in Nano-Ti O₂+5,20 and 40 mg/kg BW lycopene groups.Compared with those of the control group,the expression levels of p53,Bax,Cleaved Caspase 3,Cleaved Caspase 9,p-p38 and the ratio of Bax/Bcl-2 and p-p38/p38 in livers of mice in the Nano-Ti O₂group were significantly increased（P<0.05）,while the expression levels of Bcl-2 was significantly decreased（P<0.05）,and there was no significant difference in the expression of these apoptosis-related proteins in livers of mice in Nano-Ti O₂+5,20,40mg/kg BW lycopene groups.Compared with those of the Nano-Ti O₂group,the expression levels of p53,Bax,Cleaved Caspase 3,Cleaved Caspase 9,p-p38 and the ratio of Bax/Bcl-2 and p-p38/p38 in livers of mice in the Nano-Ti O₂group were significantly decreased（P<0.05）.Conclusion:Lycopene can alleviate Nano-Ti O₂-induced liver injury of mice through reducing oxidative damage and apoptosis.Moreover,inhibiting the ROS-p38-p53 signaling pathway which is activated by Nano-Ti O₂may be one of the important mechanisms of lycopene in alleviating liver injury induced by Nano-Ti O₂in mice.