Neurotoxity Effects Of Typical Synthetic Phenolic Antioxidants On Danio Rerio

Synthetic phenolic antioxidants(SPAs)are widely used in food production and the processing of macromolecular materials such as plastics to remove free radicals and prevent oxidation of products.Because of its high production,wide distribution,environmental persistence and biological enrichment,it has received a great deal of attention.Studies have shown that SPAs have estrogenic effects,developmental toxicity,and can cause heart defects in zebrafish(Danio rerio).However,the toxic effects of SPAs with different structures and their mode of action remain unclear.In this study,three typical SPAs(BHT,4-tOP and 2,4-DTBP)were selected,and zebrafish as the model organism.First,zebrafish larvae were exposed to BHT,4-tOP and 2,4-DTBP at a concentration of 0.1 ?M for 6 days.After that,transcriptomic analysis was conducted to preliminarily screen the interaction of three SPAs on the pathways related to the nervous system of zebrafish.In order to further study the neurotoxicity and mechanism of SPAs,we measured locomotor behavior and the expression levels of genes involved in ?-aminobutyric acid(GABA),5-hydroxytrypamine(5-HT)and dopamine(DA)pathway after exposure to three kinds of SPAs(0.01,0.1 and 1 ?M)for 6 days.The main conclusions are as follows:(1)Transcriptome analysis showed that 525,1154 and 580 differentially expressed genes were detected in BHT,4-tOP and 2,4-DTBP,respectively.Pathway analysis showed that the three SPAs co-acted in nervous system,cardiovascular development,immune system,and endocrine-related biological processes.(2)After exposure to 0.1 and 1?M BHT,heart rate and eye size were significantly inhibited in zebrafish embryos.Locomotor behavior test results showed that total swimming distance and average velocity of larvae were significantly increased after exposure to 0.1 and 1?M BHT,and larvae exhibited skototaxis behavior.Meanwhile,BHT induced significant changes in the expression of dat?drd3and mao.These results suggest that BHT may produce neurotoxicity in zebrafish by interfering with DA and 5-HT pathways.(3)Heart rate and eye size were significantly inhibited after 0.1 ?M 4-tOP exposure.The locomotor behavior test results showed that the total swimming distance and average velocity decreased significantly after 1 ?M 4-tOP exposure,and the skototaxis behavior was obvious in the anxiety test.The molecular level of 4-tOP suggesting that may induce neurotoxicity in zebrafish by interfering with DA and5-HT pathways.(4)0.1 ?M and 1 ?M 2,4-DTBP could inhibit the spontaneous movement,hatching rate and heart rate of zebrafish embryos in different degrees.Exposure to 0.1?M 2,4-DTBP inhibited larval swimming behavior.At the molecular level,0.01 ?M2,4-DTBP could significantly inhibit the expression of gat1,gad1 b and grinb in GABA pathway,and promote the expression of 5ht1 b in 5-HT pathway.Medium and high concentrations of 2,4-DTBP inhibited the expression of th1?th2?drd2b and drd2 c in the DA pathway of larva,and drd1 was significantly up-regulated after exposure.These results suggest that 2,4-DTBP may induce neurotoxicity in zebrafish by interfering with GABA,DA,and 5-HT pathways.In conclusion,SPAs may jointly produce neurotoxicity on zebrafish by interfering with GABA,5-HT and DA pathways,and exert influence on zebrafish swimming behavior and anxiety behavior.However,different structures of SPAs may have different neurotoxic mechanisms on zebrafish in the early development stage,which needs to be further studied in combination with other biological indicators.