Luzindole Attenuates LPS/D-Gal-Inuuced Liver Injury

Background:The uncontrolled inflammatory response is one of the primary mechanisms underlying the development of acute hepatitis induced by infections,autoimmune factors,drugs,toxins,etc.Lipopolysaccharide(LPS),the major virulence factor of Gram negative bacteria,is a representative stimulator of inflammation,which is extensively involved in various inflammatory disorders including acute hepatitis.Exposure to LPS in D-galactosamine(D-Gal)-sensitized mice is a widely used approach to induce acute hepatitis in experimental studies.The inflammatory response is tightly regulated by various endogenous factors,such as hormones,neurotransmitter and metabolites.Melatonin is a well-documented hormone that is mainly released from the pineal gland and plays central roles in the regulation of sleep-wake cycles.In addition,cumulative evidence suggests that melatonin also functions as a pleiotropic regulator of inflammation in peripheral tissues and experimental studies have found that melatonin might act as both an activator and an inhibitor in inflammatory response.Luzindole is a competitive antagonist of melatonin receptor,which has been widely used to block the activities of endogenous or exogenous melatonin in experimental studies.Although some studies have found that luzindole abolished the anti-inflammatory benefits of melatonin,treatment with luzindole also resulted in alleviated inflammatory injury under certain circumstance(3,4).In the present study,the melatonin receptor antagonist luzindole was administered into mice with LPS/D-Gal-induced acute hepatitis,its potential effects on inflammatory response,hepatocyte apoptosis,histological abnormalities and animal survival have been determined.Objective:To study the potential effects of luzindole on acute liver injury induced by lipopolysaccharide(LPS)/D-galactosamine(D-Gal).Methods:This study first attempted to establish a model of acute liver injury induced by LPS/D-Gal in BALB / c mice,and to detect biochemical markers and pathological changes of liver injury.Then,the melatonin-specific inhibitor luzindole was pre-treated by intraperitoneal injection for 30 min in advance,and the mice were sacrificed at 1.5 h and 6 h after LPS/D-Gal injection,respectively,and then subjected to blood collection and liver treatment.The role of Luzidole in LPS/D-Gal-induced ALI and its preliminary mechanism were investigated by blood test and WB test results to observe its protective effect and the influence of inflammatory factors and important molecules involved in signal transduction pathway.Results:Treatment with luzindole can attenuate acute liver injury induced by LPS/D-Gal and inhibit hepatocyte apoptosis.The results are as follows:(1)Luzidole inhibits the increase of ALT and AST activity in plasma induced by LPS/D-Gal.There was no significant difference between the normal control group and the drug control group.Compared with the normal control group,the serum ALT and AST activities of the model group were significantly increased,while the serum ALT and AST activities of the mice were significantly decreased after luzindole treatment.(2)Luzidole relieves abnormalities in liver tissue morphology.There was no significant difference between the normal control group and the drug control group.The liver lobule structure of mice treated with LPS/D-Gal was blurred,and the hepatocyte cell line was disordered,indicating hepatocyte necrosis accompanied by inflammatory cell infiltration.Pathological changes such as liver congestion and necrosis were significantly alleviated in the Luzindole intervention group.(3)Luzidole increases the survival rate of mice.Compared with the LPS/D-Gal model group,the luzindole intervention group significantly improved the survival rate of the mice.(4)Luzidole reduced serum TNF-α and IL-6 levels in mice.After treatment with LPS / D-Gal,the levels of TNF-α and IL-6 in the model group were significantly higher than those in the normal control group and the luzindole control group.Serum TNF-α and IL-6 levels were significantly lower than the model group after luzindole intervention.There was no difference in serum TNF-α and IL-6 levels between the normal control group and the luzindole control group.(5)Luzidole inhibits LPS/D-Gal-induced hepatocyte apoptosis.Compared with the normal control group,the TUNEL-positive apoptotic bodies in the model group were significantly increased;the number of TUNEL-positive cells in the mice was decreased after administration of luzindole.(6)Luzindole reduced LPS/D-Gal-induced up-regulation of cleaved caspase-3 and cleaved PARP-1.The expression levels of cleaved caspase-3 and cleaved PARP-1 in the model group were significantly higher than those in the normal control group,and the expression of increased protein was down-regulated after treatment with luzindole.(7)Luzidole inhibits LPS/D-Gal-induced caspase activity.Compared with the normal control group,the caspase activity of the liver tissue of the model group was significantly increased,while the treatment of luzindole decreased the activity of caspase in the liver tissue of mice.Conclusion:Treatment with luzindole can alleviate the acute liver injury induced by LPS / D-gal,suggesting that luzindole may have potential value in the intervention of inflammatory liver disease,and hope to provide some reference for the treatment of acute liver injury.