Disturbance Effect Of Pyrethroids On Endocrine And Oxidative Metabolism In Zebrafish (Danio Rerio)

Pyrethroids as a new class of potent and effective insecticides,have became the second largest insecticide in the world.Although pyrethroids are characterized as low toxic to mammals and aves,but they have been highly toxic to insects and aquatic organisms such as fish,and its aquatic toxicity has been an issue of great concern.At present,synthetic pyrethroids(SPs)has been identified as endocrine disrupting chemieals(EDCs),which can disrupt the endocrine balance and metabolic activity in vivo.But scant information is available regarding the mechanism research by SPs' s interference effects in endocrine balance and oxidative metabolism at the environment.The present study explored the developmental toxicity,disturbing effects and mechanism on endocrine balance and oxidative metabolism of zebrafish induced by the pyrethroids,while a comparative study of the differences between type I and type II pyrethroids on aquatic toxicity and interference mechanisms of endocrine balance and oxidative metabolism has been done.The main work and achievements of our study are shown as followed:(1)The pyrethroids were toxic to develop ment of zebrafish embryo,and induced the occurrence of phenomenon including coagulation,delay hatching,larval death,yolk sac edema,pericardial edema and curved body axis,after exposure to 96 hpf.According to the sublethal and lethal effects,the toxic to embryonic development of zebrafish rank as: Lambda-Cyhalothrin> Fenvalerate> Permethrin.Besides,after a week exposure,base on the lethal effects of each treatment,the toxic to adult zebrafish rank as: Lambda-Cyhalothrin(type II)> Permethrin(type I).These results indicated that pyrethroids have high toxicity on zebrafish embryo development and adult zebrafish,which also is an effective evidence of the reported results.(2)During the embryonic development of zebrafish,the expression of gonads system,thyroid system and adrenal system-related nuclear receptor gene disrupted by all of the three pyrethroids.And in the study of disturbance effects on adult zebrafish's endocrine balance,we found that exposure to Lambda-Cyhalothrin and Permethrin alter the gene transcription in the HPT axis and HPA axis of zebrafish.In particular,at the environmental treatment groups,the pyrethroids showed disturbance effect on endocrine system in larvae and adult zebrafish.These results not only expound the mechanism of alterations in endocrine balance induced by type I and type II pyrethroids,but also would help to achieve a better understanding of the environmental and eco-safety of pyrethroids in environment.(3)In this study,the pyrethroids altered the o xidative metabolism-related nuclear receptor gene expression in larval and adult zebrafish,and there were differences in their mediated modulation and effects.In the environmental treatment groups,Lambda-Cyhalothrin,Fenvalerate and Permethrin had weak influence on oxidative metabolism-related nuclear receptor gene expression in zebrafish embryo,but those gene transcription altered by Permethrin in adult zebrafish.This may be related to the protection of embryo's chorionic,and also prompted us to give more attention to the disturbances of oxidative metabolism in vivo induced by pyrethroids in environment,and necessary to be carried out in further research.