The Effects Of Disturbance On Hypothalamus-Pituitary-Thyroid (HPT) Axis In Zebrafish Larvae After Exposure To DEHP

Di-(2-ethylhexyl)-phthalate(DEHP)as one of the phthalate acid esters(PAEs)family,is the most extensive used plasticizer though the world in the production of human daily use such as infusion tube,flood bags,food packaging materials,baby toys,cosmetics,artificial leather and etc.As no stable chemical bonds to the plastic molecules in the products,DEHP is easily released into the environments.Currently,DEHP was found in the air,waters,soil environment and so on,even in the body of wild animals,human tissues,blood and breast milk.Previous reports proved that DEHP has the cell toxicity,endocrine distupting toxicity,reproduction toxicity and neurotoxicity.Since the biological amplification of the organic pollutants,the DEHP toxicity effect on the aquatic organism and human's health should be evaluated.The objective of the present study was to evaluate the disrupting effects on the thyroid hormone system in zebrafish after short time exposed to DEHP.In the present study,zebrafish embryos were exposed to different concentration of DEHP(0,40,100,200,400 ug/L)from2 hours post fertilization to168 hpf.Then the samples were collected to detect the developmental indexes and the whole-body thyroid hormones(THs)content and the key genes expression of the hypothalamus-pituitary-thyroid(HPT)axis related to the thyroid development and function.The results showed that DEHP caused no significant changes of the development indexes.However,DEHP treatment altered key genes expression significantly,and finally changed the zebrafish larvae whole-body TH content though the HPT axis pathway.Therefore,we draw the conclusion that DEHP caused the endocrine disrupting toxicity on the zebrafish larvae thyroid system.Due to the different levels of DEHP pollution and combined effects with other pollutants in the environment,the mechanisms studies on DEHP toxicity to the aquatic organism and human need to be further investigated.All results in this study provided new ideas to explore the mechanisms of DEHP disturbance on thyroid endocrine system.