A Preliminary Study On Astragalus Polysaccharide Protection Of Ochratoxin A-induced Chicken Liver Injury

Ochratoxin A(OTA)is a toxic mycotoxin which could widely found in nature.Previous studies have shown that the most important target organs of OTA are liver and kidney.Ingestion and accumulation of a low dose of OTA can cause strong organ damage.OTA-induced liver toxicity may be caused by causing oxidative stress or inflammatory reaction in the liver.Astragalus polysaccharides(APS)is from the roots of the legume plant Astragalus membranaceus or Astragalus membranaceus and can be obtained through the step of drying,extracting,concentrating and purifying.Astragalus polysaccharides are usually used as immunomodulators or enhancers to promote antibody formation.Astragalus polysaccharides also have antiviral,antitumor,anti-stress,antioxidant,lipid-lowering,anti-aging and many other effects.Previous studies have confirmed that ingestion of Astragalus polysaccharide can significantly improve the cardiac function of diabetic mice and reduce the oxidative stress damage of myocardial cells.However,the role of Astragalus polysaccharide in the liver damage by Ochratoxin has not been seen.We aimed to establish a model of chick liver injury using Ochratoxin A and tried to explore the protective effect of Astragalus polysaccharide on OTA-induced liver toxicity in chiken,and found out the possible mechanism.First,28 healthy 1-day-old white feather chicks were equally divided into 4 groups,which including blank control group and OTA group(0.5mg/kg,1mg/kg,2mg/kg).The blank group was fed with 0.5ml saline.In the OTA group,OTA was weighed according to the weight ratio of chicks at 0.5 mg/kg,1 mg/kg,and 2 mg/kg,dissolved in 0.5 ml of saline,and given OTA by oral administration of OTA solution..During the experiment,weigh the chicks every day,observe and record the chicks' feed intake and mental state.After the test,the liver tissue was taken,and HE staining method,kit,etc.were used to detect the model of liver injury and confirm the concentration of the drug used for modeling.Through analysis of the data,1mg/kg and 2mg/kg Ochratoxin A can significantly increase the ALT and AST indexes in the serum of chicks,and reduce the content of GSH-Px and SOD in the liver tissues of chicks.However,in the 2mg/kg group of Ochratoxin A,two dead chicks appeared during the experiment,which means that the concentration of Ochratoxin A at 2mg/kg body weight is too high and the toxicity is too strong.Therefore,we determined the body weight of 1mg/kg chick as the modelling concentration.The experiment selected 35 healthy broilers,randomly divided into 5 groups,7 in each group.Respectively: blank control group,OTA group(1mg/kg),APS+OTA low-dose group(APS: 50mg/kg,OTA: 1mg/kg),APS+OTA medium-dose group(APS: 100mg/kg,OTA: 1mg/kg),APS+OTA high-dose group(APS: 200mg/kg,OTA: 1mg/kg).During the test period,the chicks can freely eat and drink water,feed toxins and drugs by the feeding method,at the same time,feed once a day.This process lasts 7 days.After the test,the liver tissues were taken,and the biochemical indicators of broiler blood,histopathology,liver tissue antioxidant levels,MAPK signal transduction pathways and iNOS,COX-were detected by HE staining,kit method,Western Blotting,qPCR and other methods.2.Changes in the mRNA expression levels of Casepase-3 and Bax signaling pathway related genes.The results showed that:(1)OTA caused obvious growth inhibition and liver damage in broilers,which showed that the body weight of broilers in the OTA group significantly reduced.The liver organ coefficient was significantly increased and the liver histological structure was changed.(2)Astragalus polysaccharides can inhibit liver function damage caused by OTA.Astragalus polysaccharides significantly improve liver histological structure damage and play an antagonistic role in OTA-induced liver toxicity.(3)APS can inhibit the change of antioxidant status of broiler liver tissue caused by OTA exposure,increase the activity of T-SOD and GSH-Px(4)APS inhibits MAPK signaling pathway.And reduce the expression of ERK,P38 and its downstream genes,improve the body's ability to resist oxidative stress,and interfere with the toxicity of broiler liver caused by OTA exposure.(5)APS can increase the body's ability to resist oxidative stress by inhibiting the mRNA expression levels of Casepase-3 and Bax signaling pathway related genes,and interfere with the toxicity of broiler liver caused by OTA exposure.In summary: Ochratoxin A can quickly and stably establish a model of liver damage in chicks;APS can effectively reduce the liver tissue damage caused by OTA in broilers.APS may antagonize MAPK,iNOS,COX-2,Casepase-3,Bax signaling pathways OTA-induced oxidative damage.