Protective Effect And Mechanism Of Taurine On AFB1 Induced Injury In Rats

Aflatoxin B1(AFB1)is the most toxic aflatoxin(AF)and the most effective carcinogen.It is widely found in peanuts,corn,wheat and other grains,which seriously threatens the health of human beings and animals.AFB1 is mainly metabolized in the liver,producing toxic substances that damage the hepatic structure and function.Meanwhile AFB1 metabolites are mainly excreted from the kidney,which can cause irreversible damage to the kidney.AFB1 toxicity can also affect the spleen,causing inflammation in the body and lowering immunity.Taurine is a conditioned essential amino acid in human beings and most mammals,which has antioxidant,anti-inflammatory,immune-enhancing and body protective effects,but its effect on liver,kidney and spleen function damage caused by AFB1 poisoning is still unclear.In this experiment,the rat model of AFB1 poisoning was prepared,and taurine was added into the drinking water to explore the protective effect and mechanism of taurine,so as to provide theoretical basis for the application of taurine to prevent AFB1 poisoning.In experiment 1,SD rats were randomly divided into 3 groups: 250 μg/kg B.W AFB1 were intragastrically administered to rats in order to establish AFB1 toxic rat model.Rats in the normal control and solvent control group were intragastrically administered with salin or DMSO.After 40 days,liver,kidney and spleen were collected,paraffin sections and HE staining were performed to observe the pathological changes.The results showed that the histological structure of the liver,kidney and spleen were normal.In the AFB1 model group,the hepatic lobules remained,the hepatic cell cords were disordered,and the cells had granulopathy and steatosis.The epithelial cells of renal tubules were swollen and the cytoplasm was granular degeneration.Spleen red pulp congestion,white pulp lymphocyte reduction,white pulp atrophy red pulp,white pulp demarcation is not clear.No significant pathological changes were observed in liver,kidney and spleen of rats in DMSO group.The results indicated that continuous gavage of AFB1 for 40 days caused liver,kidney and spleen damage in rats,and AFB1 poisoning rat model was successfully prepared,while DMSO alone had no significant effect on organ structure.In experiment 2,SD rats were randomly divided into 7 groups: rats in the normal control group(C),solvent control group(DMSO)and model group(M)were treated the same as experimental one,rats in taurine control group(T)and taurine interventive group(MT)were given 1%,2% and 3% taurine respectively added in drinking water.Blood and urine were collected at the end of the experiment,liver function,kidney function indexes and blood immunoglobulin levels were measured.The experimental results showed that the rats in the model group had decreased food intake and body weight compared with the control group.Liver and kidney indexes increased obviously,spleen index decreased significantly.Serum ALT,AST,ALP,LDH,BUN,CRE,UA,cys-c,urine ALP and m ALB were significantly4 increased.The contents of serum immunoglobulin A(Ig A),immunoglobulin M(Ig M)and immunoglobulin G(Ig G)were significantly reduced.The food intake and body weight of rats in taurine intervention group was significantly improved compared with the model group.Liver and kidney index decreased,spleen index increased significantly.Serum ALT,AST,ALP activity,LDH activity,BUN,CRE,UA,cys-c levels,urine ALP,m ALB levels were significantly increased.Serum concentrations of Ig A,Ig M and Ig G lowered obveriously compared with normal rats,among which 2% and 3% taurine intervention effects were better than 1% taurine.Taurine control group and DMSO control group showed no significant difference when compared with the normal rats.The above results indicated that taurine could alleviate the poisoning symptoms of AFB1 in rats,improve the pathological damage of liver,kidney and spleen tissues caused by AFB1,and improve the liver,kidney and humoral immune function of rats,so as to protect rats from the toxic damage caused by AFB1 to a certain extent.In experiment 3,rats were selected and divided into 5 groups: normal control group(C),taurine control group(T),DMSO control group and model group(M)rats were treated in the same way as in experiment 2.Taurine intervention group(MT)rats were treated with 2%taurine on the basis of modeling.At the end of the 40-day experiment,liver,kidney and spleen were collected to detect antioxidant capacity,liver mitochondrial function,liver and kidney cell apoptosis,m RNA expression levels of factors related to Nrf2 signaling pathway and apoptosis pathway in liver and kidney,liver and spleen inflammatory factors and TLR4 pathway related gene expression levels.The results showed that catalase(CAT),glutathione peroxidase(GSH-Px),superoxide dismutase(SOD),total antioxidant capacity(T-AOC)and glutathione(GSH)activity/content in liver,kidney and spleen of the model group were significantly decreased,while MDA level was significantly increased.The expressions of Nrf2,NQO1,HO-1,GCLC,GSH-Px and SOD m RNA in liver and kidney were significantly decreased.The levels of mitochondrial membrane potential(MMP),mitochondrial uncoupled protein 2(UCP2),carnitine palmitoyl transferase(CPT-1),cytochrome C oxidase(COX)and NADPH cytochrome C reductase(NCR)were significantly reduced.The apoptosis rates of liver and kidney cells were significantly increased,the m RNA expressions of Bax,Bak-1,Apaf-1,Caspase 9 and Caspase 3 were significantly increased,and the m RNA expressions of Bcl-2 were decreased.The levels of TNF-α,IL-1β,IL-6 in the liver and spleen were significantly increased,and the expressions of TLR4,CD14,My D88,NF-κB and p65 m RNA were significantly increased.Compared with the model group,the activity/content of liver,kidney,spleen CAT,GSH-Px,SOD,T-AOC and GSH in the intervention group were significantly increased,and the MDA level was significantly decreased.The expressions of Nrf2,NQO1,HO-1,GCLC,gsh-px and SOD m RNA in liver and kidney were significantly increased.Liver line MMP,UCP2,CPT-1,COX and NCR levels were significantly increased.The apoptosis rates of liver and kidney cells were significantly decreased,the m RNA expressions of Bax,Bak-1,Apaf-1,Caspase 9 and Caspase 3 were significantly decreased,and the m RNA expressions of Bcl-2 were significantly increased.The levels of TNF-α,IL-1β,IL-6 in the liver and spleen were significantly decreased,and the expressions of TLR4,CD14,My D88,NF-κB and p65 m RNA were significantly decreased.The above results indicate that:(1)Taurine can promote the transcription and translation of antioxidant enzymes by up-regulating Nrf2 signaling pathway in AFB1 poisoned rats,enhance the antioxidant capacity of rat liver,kidney and spleen,and protect the body from the oxidative stress injury caused by AFB1.(2)Taurine can maintain the normal mitochondrial membrane potential and mitochondrial function in AFB1 poisoned rats,and reduce the apoptosis of liver and kidney cells caused by AFB1 through inhibiting the mitochondrial apoptosis pathway.(3)Taurine can down-regulate the expression of TLR4 and its downstream signaling pathway in AFB1 poisoned rats,inhibit the transcription and response of inflammatory factors,and further inhibit the inflammatory injury of liver and spleen caused by AFB1.