Endocrine disruption and reproduction impairment in zebrafish after long‐term exposure to DE‐71
Our objective was to investigate the impact of Polybrominated diphenyl ethers (PBDEs) on fish reproduction over two generations. Zebrafish (Danio rerio) embryos (F0) were exposed to low concentrations (3, 10, 30 μg/L) of the PBDE mixture DE‐71 until they were sexually mature, and steroid hormone production, expression of genes involved in steroidogenesis, gonadal development and gamete characteristics were examined. Exposure of female zebrafish to DE‐71 resulted in lower estradiol (E2) production and down‐regulation of cytochrome P450 aromatase (CYP19a and CYP19b) mRNA. In males, exposure to DE‐71 resulted in greater testosterone (T) production and greater cytochrome P450 c17 α‐hydroxylase, 17, 20‐lase (CYP17) mRNA expression. Moreover, hepatic vitellogenin (VTG) mRNA and estrogenic receptor (ERβ) gene transcription were down‐regulated in females and males. Expression of the follicle‐stimulating hormone β (FSHβ) gene in the pituitary was up‐regulated and the expression of luteinizing hormone β (LHβ) was down‐regulated in both sexes. Histological examination showed inhibition of oocyte maturation in females and retarded spermiation in males. The average number of eggs (F1) produced was also reduced. Additionally, exposure of F0 embryos to DE‐71 did not result in developmental toxicity, whereas delayed hatching, reduced survival and decreased growth were observed in the F1 embryos derived from parent fish exposed to DE‐71. Therefore, long‐term exposure to low concentrations of PBDEs in zebrafish could cause reproductive impairment, suggesting that PBDEs may have significant adverse effects on fish population in the highly PBDEs‐contaminated aquatic environment. Environ Toxicol Chem © 2014 SETAC
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