Study On The Toxicological Effects And Metabolic Effects Of Acetamiprid On The Liver Of African Clawed Frog

Acetamiprid,the first generation of new neonicotinoid insecticide,which is widely used to control aphids,plant hoppers,thrips and some lepidoptera pests in rice,vegetables,fruit trees and tea.Only approximately 2～20%of acetamiprid,which is mainly used for foliar spraying,is assimilated by the crops,and the rest enters the environment.Because of the high water solubility,it reaches the water body through rainwater scouring and water and soil erosion,resulting in water pollution and posing a threat to the survival of aquatic non-target organisms.At present,limited information is available on the toxic effects of acetamiprid on nontarget aquatic organisms.In this paper,the hepatotoxity and metabolic effects of acetamiprid on Xenopus laevis,a typical model organism as the environmental carrier.The research contents and conclusions are as follows:（1）The acute toxicity test of acetamiprid on X.laevis was performed.The LC₅₀value of acetamiprid on X.laevis for 96 h was 64.48 mg/L,indicating that acetamiprid was low toxicity to X.laevis.X.laevis poisoning was characterized by convulsions of limbs,vomiting of white viscous substances and body rollover.（2）A HPLC-MS/MS method for the determination of acetamiprid in water and X.laevis liver was established.The limit of detection（LOD）and limit of quantification（LOQ）of acetamiprid in water were 0.0002 mg/L and 0.0007 mg/L,respectively,and the LOD and LOQ in livers were 0.003 mg/kg and 0.001 mg/kg respectively.The detection of acetamiprid in water samples confirmed that during the exposure process,the concentration range of the high and low concentration(1/10 LC₅₀and 1/100 LC₅₀)groups at each stage before water renewing were 6.3567±0.0368 and 0.6398±0.0064mg/L,respectively,indicating that the concentration of acetamiprid was stable during the exposure process.After 28 d of exposure,acetamiprid contents in the livers were5.547±0.1724 and 0.6443±0.0661 mg/kg in the high and low concentration groups,respectively,indicating that acetamiprid accumulated in the liver.（3）Antioxidant enzyme activities and MDA contents in the livers of X.laevis were studied after exposure to acetamiprid for 28 d.The activities of antioxidant enzymes and GST were both induced and activated,and the content of MDA increased,indicating that acetamiprid exposure led to oxidative stress of X.laevis,causing oxidative damage to liver tissue.（4）Hematoxylin and eosin（H&E）staining observation was carried out within 28d to determine the effect of acetamiprid exposure on liver tissue of X.laevis.Histopathological sections showed that low concentration exposure resulted in inflammatory infiltration.Under high concentration exposure,inflammatory infiltration in the liver futher expanded and also liver showed fat vacuoles and hepatocyte necrosis,indicating a certain degree of liver function damage.The higher the concentration of acetamiprid,the greater the damage to liver tissue.（5）The untargeted metabolomic analysis identified the endogenous metabolites that were significantly altered.There were 89 differential metabolites compared to the controls:64 in the high concentration group,47 in the low concentration group,and 23metabolites in the high concentration group were the same as those in the low concentration group.Sixteen pathways that were mainly associated with amino acid metabolism and lipid metabolism,such as sphingolipid metabolism,glycerophospholipid metabolism and histidine metabolism,indicating that acetamiprid exposure disrupted the metabolism of the body and further revealing the essence of liver injury.