Research On The Development Effects And Endocrine Disruption Of BDE-99 In Zebrafish Embryo/Larvae

As a brominated flame retardant, PBDEs have been widely used in furniture, textiles, buildings and electronic products. However, they have serve side effects on environment and human health. Therefore, we tried to investigate their reproductive development and endocrine disruption effect and then evaluate their ecotoxicity in this study. As a type of PBDEs, BDE-99 was chosen as the representative compounds, and zebrafish was chosen as a testing specie.In this study, does-response and embryo/larvae at the early developmental stages effects on zebrafish was studied by applying exposure in water. Results indicated that LC50 decreased by time, and LC50 did not change after 96h with a concentration of 707 μg/L; hatching rate increased significantly from 24h to 48h, and at 96h, all embryos became larvas. In early exposure, the hatching rate of 2 μg/L was highest to 17%; high toxicity concentration groups resulted in abnormal development, and in the late stage of waterborne exposure experiment, high concentration resulted in larvae with edema and malformed spin.In order to judge whether BDE-99 affected the normal function by influencing the biological signal pathways of HPT and HPA axis, q-RT-PCR technique was used to detect the mRNA expression of HPA and HPT axis related genes in zebrafish, which was exposed to BDE-99 after 120hpf. After exposure to BDE-99, most related genes in zebrafish in the mRNA expressions of HPA and HPT axis were affected in different degree, on HPT axis, compared to control, the mRNA expression of TTR and TRH had no obvious change; in 2μg/L, the mRNA expressions of TSHb、TSHR、TG、 TRb、NIS were up-regulation significantly, and as a core gene, TRb was up-regulation 2.07 times after exposure. On HPA axis, the mRNA expressions of all genes decreased by time, most genes expressions less than 2 times. In sum, BDE-99 has some effects on endocrine system in zebrafish.Q-RT-PCR technique was also used to detect the mRNA expression of eight receptors genes and associated genes. Eight receptors are Aryl hydrocarbon receptor(AhR), Peroxisome proliferator activated receptor(PPAR), Pregnane x receptor(PxR), Androgen receptor(AR), Glucocorticoid receptor(GR), Mineralocorticoid receptor(MR), Thyroid hormone reseptor(TR)and Estrogen receptors(ER). This research suggested that the expression of the genes in high concentration had obvious change compared to lower concentration. Expression of mRNA in some genes had no changes while most had changes in three concentration. Amout of BDE-99 in embryos increased by time extended. BDE-99 might AhR、GR、 ERs、PxR mediated. Further study would be focused on the endocrine disruption mechanism of other receptors.