Study Of Accumulation Of Phthalates Esters Into Mice Transferred By Microplastics And Their Toxic Effects

Recent microplastics(MPs)were constantly detected in various environmental media.Simultaneously,MPs could be ingested by many aquatic organisms and induce many toxic effects,such as oxidative stress,abnormal energy metabolism and inflammation.In addition,due to the hydrophobic of MPs surface,organic contaminates could be adsorbed and transferred by MPs into bodies of marine organisms and would induce more serious toxicities.Phthalates esters(PAEs)are typically used as plasticizers in plastic products,hence MPs would adsorb PAEs as combined pollutants.However,so far there is not any report about MPs adsorbed and transferred PAEs into organims.Compared to aquatic organisms,MPs could also be ingested into terrestrial mammals and even humans through diets and respirations.Based on the above background,this study first studied the distribution and potential toxic effects of virgin MPs,and toxic effects and potential mechanisms of PAEs transported by MPs in mice.The main research results are as follows:(1)Accumulation of MPs in mice tissues and its corresponding toxic effects:After exposure to 5 and 20?m fluorescent spherical PS MPs(0.1Omg/day)for 28 days,5?m MPs in the mice tissues were(1.39±0.14 mg/g)>kidney(0.95±0.01 mg/g)>liver(0.30±0.03 mg/g).The concentrations of 20?m MPs were in the mice liver(0.76±0.07 mg/g),kidney(0.78±0.08 mg/g),and gut(0.78±0.08 mg/g),and no significant difference were observed in those three tissues.The enriched concentrations in different tissues were significantly related to the sizes of MPs.On the other hand,after uptake MPs,the levels of GSH-Px,SOD and LDH in the liver significantly increased,whereas CAT,ATP,T-CHO and TG significantly decreased,which indicated that MPs induced oxidative stress and abnormal energy metabolism in the liver of mice.In addition,the metabolomics analysis of mouse serum showed that metabolic profile and metabolites were significanted changed after uptake MPs.Moreover,the significant changed mtebolites(SCMs)including phosphocreatine,succinate,creatine,2-oxoglutarate,alanine,pyruvate,glutamine,citrate,choline,lysine,and phenylalanine were significantly decreased in MPs treatment groups,whereas taurine,threonine,lipids and aspartate were significantly increased.Those SCMs were involved the biological processes of oxidative stress,energy metabolism and lipid metabolism.Hence,MPs could significantly affect oxidative stress,energy metabolism and lipid metabolism in mice.(2)Accumulation of PAEs in mice tissues transferred by MPs:PE spherical MPs with different size range(0.7-5?m,S-MPs;45-53?m,L-MPs)were selected to interact with the 4 typical PAEs(DBP,DEHP,DEP,and DMP;5 and 50?g/L).The DEHP(50?g/L)on S-MPs and L-MPs were 154.32±20.76 ?g/g and 70.27±7.89,respectively,which were significant higher than the concentrations of other 3 PAEs(DBP,DEP,and DMP)on MPs.The mix PAEs(50?g/L)on S-MPs and L-MPs were 176.07±20.54 ?g/g and 92.29±10.13,repsectively.On the other hand,the PAEs on MPs can be transferred by MPs into mouse testis,liver,kidney and intestine.The concentrations of single PAEs transferred by MPs in the mice gut was significantly higher than that in testis,liver and kidney,especially S-MPs.The concentrations of DEHP(471.28±20.53 ng/g)in mice gut transferred by S-MPs were significantly higher than for DBP(356.29 ±9.52 ng/g),DEP(174.89±8.89 ng/g),and DMP(211.66±26.11 ng/g).In addition,there was no significant difference between the concentration of mix PAEs and single DEHP transferred by MPs in mice tissues.(3)The toxic effects and mechanism in mice gut after uptake MPs and PAEs:After MPs transferred DEHP and mixed PAEs into mice gut,DAO significantly decreased and D-Lac significantly increased,which meant the intestinal permeability of mice were significantly changed.MPs+PAEs could change the expression of gut transcripts.On the other hand,MPs+PAEs could change the mice gut microbiota diversity and structure.Relative levels of microbes were changed by MPs+ PAEs,which related to energy metabolism,lipid metabolism {Actinobacteria and Proteobacteria decreased),and immunity(Anaeroplasma and Dorea decreased).Based on above results,the oxidative stress,energy metabolism,lipid metabolism,hormone metabolism,and immune functions were significantly changed by MPs+PAEs.Finally,the serious toxic effects were observed after treated with MPs+PAEs.Besides GO trems related to hormone metabolism were observed in MPs+DEHP treatment,no significant difference between MPs+DEHP and MPs+MIX treatments.In addition,H2-DMb2,H2-Eb1,Cyp2a5,Cyp1a2,Gm8909,Aldh8al,Scarbl,and Rdh16 were selected as biomarkers for the toxic effects of MPs+PAEs.Although more DEHP in gut transferred by S-MPs,DEHP transferred by L-MPs had higher bioavailability than that transferred by S-MPs.(4)The toxic effects and mechanism in mice testicle after uptake MPs and PAEs:After MPs transferred DEHP and mix PAEs into mice testicle,the relative weight of testicle,sperm vitality and quantity were significantly decreased.The results of electron microscopy revealed that mitochondrial swelling and ridge structure were blurred in testicular cells.The levels of SOD,MDA,LDH and ACP in testicle significantly increased,whereas SDH significantly decreased,which indicated that oxidative stress and abnormal energy metabolism in mice testicle.On the other hand,the transcriptome analysis of testis showed that the MPs+DEHP could induce differential expression of genes related the male reproductive development.Moreover,Bik,Col9a3,Rxfp2,and lnsl3 were selected as biomarkers of reproductive toxicity after uptake MPs and PAEs.Besides GO trems related to reproductive development were observed in MPs+DEHP treatment,no significant difference between MPs+DEHP and MPs+MIX treatments.In summary,this research uncovered the accumulation of PAEs in mice liver,kindey,gut and testicle,which transferred by MPs.The toxic effects of mice gut and testicle induced by MPs+PAEs were more serious than those induced by virgin MPs.Additionally,the potential toxic mechanism of MPs+PAEs in mice gut and testicles were deduced in this research.The results could provide useful suggestions for toxicity evaluation and risk control of MPs combined with other pollutants in water.