Protective Effect Of PBC2 On Acute Liver Injury Induced By AFB₁ In Rats

ObjectiveAflatoxins（AFT）are a class of structurally similar compounds that are metabolized primarily by Aspergillus flavus and parasiticus.Aflatoxin B1（AFB₁）,the most toxic compound of AFT,has strong teratogenic,mutagenic and carcinogenic effects.Its main target organ is liver,which can cause degeneration,necrosis and hyperplasia of liver cells.In severe cases,carcinogenesis can be induced.In warm and humid climates,molds tend to grow and produce AFB₁,contaminating various types of food,causing great harm to health.Oligomeric proantho cyanidins（OPC）are widely found in fruits,vegetables,petals,seeds andothernaturalplants,belongingtopolyphenolic phytochemicals.Proanthocyanidin B2（PCB2）is a common dimer of oligomeric proantho cyanidins,which has anti-oxidation,blood vessel protection,anti-inflammatory,anti-cancer and other effects.But there are few reports on the intervention of PCB2 on AFB₁ induced liver injury.The purpose of this study was to explore the protective effect of PCB2 on acute liver injury induced by AFB₁ and to explore its possible mechanism.This study can lay the foundation for the future research of AFB₁-induced（sub）chronic liver injury and liver cancer intervention by PCB2 and provided some theoretical basis for the future prevention of AFB₁ dietary guidance and the development of AFB₁ therapeutic drugs.MethodsForty male SD rats were randomly divided into control group,AFB₁exposure group,PCB2 intervention group and PCB2 control group,with 10 rats in each.The body weight distribution of each group was similar.After 5 days of preconditioning,rats in control group and AFB₁ model group were treated with double distilled water continuously for 5 days,once per day.Rats in PCB2intervention group and PCB2 control group were treated with PCB2 solution at a dose of 30mg/kg gavage for 5 days,once a day.On the sixth day of gavage,rats in control group and PCB2 control group were intraperitoneally injected with DMSO solution;rats in AFB₁ exposure group and PCB2 intervention group were given intraperitoneal injection of 2mg/kg AFB₁ solution.Then observed for48 hours.During the period of observation,each group of rats was still administered with the corresponding solution.After 48 hours,all the rats’whole blood and liver tissues were taken for detecting liver function（AST,ALT,TBIL,DBIL and ALP）,pathology,organ index（liver index,spleen index,kidney index）,oxidative damage（CAT,SOD,GSH,MDA,8-OHdG）,inflammatory factors（IL-6 gene expression and concentration）and apoptosis related indicators（bcl-2,bax gene and protein expression）.Results1.The liver histopathology was observed under 400 times microscope.The liver tissue of the control group had a clear and tidy texture,the liver cells were polygonal with clear edges.The liver tissue of AFB₁ exposure group was disorder,inflammatory cell infiltration and punctate necrosis could be seen.There were balloon-like changes in liver cells,and the border between cells is not clear.As for PCB2 intervention group,the whole liver tissue was texture relatively clear and tidy,inflammatory cell infiltration decreased,the degree of hepatocellular degeneration was reduced.The liver tissue of PCB2 control group was basically the same as control group.2.The levels of ALT,AST,TBIL,DBIL and ALP in AFB₁ exposure group were significantly higher than those in control group（P<0.01）.The levels of ALT,AST,TBIL,DBIL and ALP in PCB2 intervention group were significantly lower than those in AFB₁ exposure group（P<0.05）,while higher than those in control group（P<0.01）.The liver function of PCB2 control group was basically the same as that of control group（P>0.05）.3.The weight gain of AFB₁ exposure group rats was lower than that of the control group rats（P<0.05）,and the liver index,spleen index and kidney index were higher than those of the control group rats（P<0.01）.The liver index and renal index of PCB2 intervention group rats were lower than those of AFB₁exposure group rats（P<0.01）,while spleen index was higher than that of control group rats（P<0.05）.The weight gain,liver and kidney index of rats in the PCB2control group were the same as those in the control group（P>0.05）,while the spleen index was higher than that in the control group（P<0.01）.4.The levels of CAT,GSH and SOD in the liver tissue of AFB₁ exposure group rats were lower than those of the control group（P<0.01）,while the level of serum MDA and the level of 8-OHdG in the liver were higher than those of the control group（P<0.01）.The levels of CAT,GSH and SOD in liver tissue of PCB2 intervention group rats were higher than those of AFB₁ exposure group rats（P<0.05）,while the level of serum MDA and the content of hepatic 8-OHdG in PCB2 intervention group were lower than those in AFB₁ exposure group（P<0.05）.The level of CAT and GSH in liver tissue of PCB2 intervention group was lower than that of control group（P<0.01）,the serum MDA level and the content of 8-OHdG in liver tissue were higher than those in control group（P<0.01）,while the level of SOD was similar to control group（P>0.05）.The contents of CAT,GSH,SOD,8-OHdG in liver tissue and serum MDA of PCB2control group were basically the same as the control group（P>0.05）.5.The relative expression level of IL-6 gene and the concentration of serum IL-6 in the liver of AFB₁ exposure group rats were significantly higher than those of the control group rats（P<0.05）.The relative expression level of IL-6gene and the concentration of serum IL-6 in PCB2 intervention group were lower than those in AFB₁ exposure group（P<0.05）,and the concentration of IL-6 in PCB2 intervention group was higher than that in control group（P<0.01）.The relative expression level of IL-6 gene and the concentration of serum IL-6in PCB2 control group were similar to those in control group（P>0.05）.6.The relative expression of bcl-2 gene and protein in liver tissue of AFB₁exposure group rats was lower than that in control group rats（P<0.01）,and the relative expression of bax gene and protein was higher than that in control group（P<0.01）,bcl-2/bax ratio was lower than control group（P<0.01）.The relative expression of bcl-2 gene and protein in rats of PCB2 intervention group was higher than that in AFB₁ exposure group（P<0.01）,the relative expression of bax gene and protein was lower than that in AFB₁ exposure group（P<0.05）,the ratio of bcl-2/bax was higher than AFB₁ exposure group（P<0.01）.The expression of bcl-2 gene and protein and bcl-2/bax ratio were lower in PCB2 intervention group than that in control group（P<0.01）,while the expression of bax gene and protein was higher in PCB2 intervention group than in control group（P<0.05）.The ratio of bcl-2 and bax genes and protein expression and bcl-2/bax ratio in PCB2 control group were similar to those in control group（P>0.05）.ConclusionPCB2 is safe and has a protective effect on acute liver injury induced by AFB₁,which is mainly reflected in improving liver function,reducing liver tissue pathological and oxidative damage,improving weight gain and liver and renal index,reducing inflammation,and upregulating bcl-2/bax gene and protein ratio.