| Background The mortality rate of acute liver failure is extremely high. Its mechanism isso complicated that there hasn’t been any effective medicine to cure it until now. More andmore evidence suggests that oxidative stress is one of the important mechanisms of acuteliver injury. The nuclear transcription factor Nrf2is an important transcription factorregulating oxidative stress reaction, and may be an important therapeutic target for acuteliver failure. Antioxidant effect of astragaloside Ⅳ has now been widely recognized, butthere are few reports about whether it could protect ALF, and whether it plays an importantrole in regulating Nrf2.Objective To observe the early protective effect of AS-Ⅳ on D-GalN/LPS-induced acuteliver failure in mice and to study its effect on the expression of Nrf2-HO-1and Bcl-2/Bax,then explore the antioxidative and anti apoptotic mechanism of AS-Ⅳ in acute liver failure.Methods The study includes two parts.(1) Seventy male C57BL/6mice were randomlydivided into5groups: the normal control group, the model group, the AS-Ⅳ low dose(A-L) group, the AS-Ⅳ medium dose (A-M) group and the AS-Ⅳ high dose (A-H) group,15mice in each group besides10in normal control group. Different dosage of AS-Ⅳ wasadministrated by gavage to the three intervention groups for three days, at the same time,cosolvent was given to the normal control group and the model group. Then the normalcontrol group was given normal saline by intraperitoneal injection, while the other fourgroups were given D-GalN and LPS by intraperitoneal injection to establish mice modelsof ALF. To observe the symptoms and the survival situation of mice in each group within48h. To count mice at the different time points, draw survival curves and do analysis about survival rate of each group.(2) fifty male C57BL/6mice were randomly divided into5groups (the same as above),10mice in each group. With the same method of modeling andAS-Ⅳ intervention, all survival mice were killed by dislocation at this point of time that6hafter modeling. Blood samples were collected and assayed for ALT and AST; grossmorphology of the liver was observed by the naked eye, pathological changes of hepatictissue were examined by HE staining, and hepatic apoptosis was determined by TUNEL;Real-Time PCR was applied for detection of Nrf2, HO-1, Bcl-2, Bax, Caspase-3mRNAexpression; the activity of SOD was tested by xanthine oxidase method, the content ofMDA was tested by thiobarbituric acid method; Western Blot was applied for detection ofNrf2, HO-1, Bcl-2, Bax, Caspase-3protein expression.Results (1) The survival rate within48h of mice in the A-H group was increasedsignificantly (60%vs13.3%, p<0.05); in the A-M and A-H group, the level of ALT inserum (1889.00±980.11vs7435.20±2493.07and154.11±69.18vs7435.20±2493.07,p<0.01) and the level of AST (1310.00±134.35vs4369.80±1960.90and146.65±76.41vs4369.80±1960.90, p<0.01) were all significantly lower than that in the model group, andthe hepatic pathological index was improved significantly (0.19±0.13vs0.40±0.00and0.11±0.08vs0.40±0.00, p<0.01).(2) The content of MDA in the A-L, A-M and A-H groupwere decreased significantly (86.03±4.38vs105.73±9.09,56.62±14.11vs105.73±9.09and41.79±5.05vs105.73±9.09, p<0.01); however, in the A-H group, the activity of SOD wasenhanced significantly (81.90±18.58vs61.16±7.85, p<0.05), the expression of Nrf2protein (1.15±0.28vs0.42±0.02, p<0.01), the expression of HO-1protein (1.28±0.14vs0.50±0.06, p<0.01), the expression of Nrf2mRNA (1.07±0.25vs0.29±0.10, p<0.01) andthe expression of HO-1mRNA (5.85±0.36vs1.06±0.14, p<0.01) were all significantlyhigher than that in the model group.(3) The hepatocyte apoptosis index in the A-L, A-Mand A-H group were decreased significantly (8.6%±5.2%vs25.1%±11.2%,5.0%±2.7%vs25.1%±11.2%and1.8±0.8%vs25.1%±11.2%, p<0.05); in the A-M and A-H group,the expression of Bcl-2/bax protein (1.39±0.18vs0.30±0.13and1.95±0.25vs0.30±0.13, p<0.01) and the expression of Bcl-2/bax mRNA (0.82±0.08vs0.55±0.10and0.92±0.14vs0.55±0.10, p<0.01) were all increased significantly, but the expression of Caspase-3protein (2.72±0.16vs4.65±0.43and1.86±0.15vs4.65±0.43, p<0.01) and the expressionof Caspase-3mRNA (2.49±0.04vs3.58±0.14and1.32±0.48vs3.58±0.14, p<0.01) weresignificantly lower than that in the model group.Conclusion AS-Ⅳ has significant protective effect on D-GalN/LPS-induced acute liverfailure in mice. Its mechanism may be related to the enhanced expression of antioxidantprotein HO-1by Nrf2, which can alleviate the acute liver injury induced by oxidativestress, and the up-regulation of the expression of anti apoptosis protein Bcl-2, butdown-regulation of Bax, Caspase-3, inhibiting hepatic apoptosis. |
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