Toxicological Effects And Mechanism Of Tricresyl Phosphate On Reproduction Of Medaka(oryzias Latipes)

Organophosphorus flame retardant(OPFRs)is an emerging flame retardant due to the increasing production and consumption constantly.Although OPFRs have been detected widely in aquatic environment,the potential impacts of reproductive on fish and the mechanism are not well studied,which limits the ecological risk assessment for them.The present study investigated the reproductive effects of Triphenyl phosphate(TCr P),one kind of OPFRs,using in vitro and in vivo.Firstly,the binding activities of TCr P with AR and m ER were evaluated by the yeast two-hybrid system,respectively.The results showed that TCr P had no binding activity with m ER,but AR antagonistic activity(IC50=47.0??),suggesting TCr P might cause reproductive damage to male fish.Then,juvenile medaka(1 dph)was exposed to TCr P to unveil the adverse effects of TCr P(8?40?200?g/L)on fish reproduction.After 100 dph,the intersex of male was found in 657.8-4041.8 ng/L of TCr P,and 21.9%occurred in the highest concentration group(p<0.01)with an obvious dose-effect relationship.Moreover,the fertilization rate(12.8%,p<0.05),hatching rate(7.5%,p<0.01)and reproductive success rate(50%,p<0.01)were also decreased in males exposure to the highest concentration of TCr P.Compared to the controls,plasma T(81.1%,p<0.05)and 11-KT(46.5%,p<0.05)decreased significantly in males exposure to the highest concentration of TCr P,while the estrogen level increased significantly(1.92-fold,p<0.05),and the VTG2 m RNA transcription level(1.74-fold,p<0.05)was also significant increased,implying that,besides via antagonizing AR,TCr P could also induced intersex by decreasing androgens and increasing estrogen levels.Lastly,the present study found the metabolites of TCr P also showed strong AR antagonistic activities OH-TCr P(IC50=23.62?M)and CH₂OH-TCr P(IC50=9.24?M),indicating that the CH₂OH-TCr P might also play an important role on the intersex incidence of medaka exposure to TCr P.All these results demonstrated the adverse impacts of TCr P on reproductive of medaka by AR pathway,which provide the scientific evidences for revealing TCr P ecotoxicity risk assessment.