Endocrine disruption and reproduction impairment in zebrafish after long‐term exposure to DE‐71

Abstract

The objective of the present study was to investigate the impact of polybrominated diphenyl ethers (PBDEs) on fish reproduction over 2 generations. Zebrafish (Danio rerio) embryos (F0) were exposed to low concentrations (3 mg/L, 10 mg/L, and 30 mg/ 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 production and downregulation of cytochrome P450 aromatase mRNA. In males, exposure to DE-71 resulted in greater testosterone production and greater cytochrome P450 c17 a-hydroxylase,17,20-lase mRNA expression. Moreover, hepatic vitellogenin mRNA and estrogenic receptor b gene transcription were downregulated in females and males. Expression of the follicle-stimulating hormone b gene in the pituitary was upregulated, and the expression of luteinizing hormone b was downregulated 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 might have significant adverse effects on fish population in the highly PBDEs-contaminated aquatic environment. Environ Toxicol Chem 2014;33:1354-1362. # 2014 SETAC

Localization of steroidogenic enzymes and Foxl2a in the gonads of mature zebrafish ( Danio rerio )

“…the higher circulating concentrations of estradiol in female zebrafish(Deng et al, 2010; Liu et al, 2012;Ma et al, 2012;Ji et al, 2013; Liu et al, 2013; Lu et al, 2014;Yu et al, 2014; …”

Exposure to a PBDE/OH‐BDE mixture alters juvenile zebrafish (Danio rerio) development

“…The differential responses we observed may reflect differences in life stage and exposure conditions, including the presence of 6‐OH‐BDE‐47 and 2,4,6‐TBP in the exposure mixture along with DE‐71. In addition to effects on thyroid homeostasis, long‐term exposure to DE‐71 can elicit reproductive effects through altered sex ratios, decreased gamete quality, and altered steroidogenesis . Reproductive endpoints were not evaluated in the present study, so further studies are needed to discern potential effects of PBDE/OH‐BDE mixtures on reproductive maturation.…”

Ecotoxicological Risk of Endocrine Disruptors

“…Because it has been observed in many fish species (Bahamonde et al, 2013;Blazer et al, 2012Blazer et al, , 2014Yonkos et al, 2014), it could be an important determinant of reproductive performance, particularly in rivers where there is a high prevalence of moderately to severely feminized males (Harris et al, 2011). Yu et al (2014) have investigated the impact of low doses of PBDEs on the reproduction of zebrafish over two generations. Several reproductive endpoints showed impairments in F0 specimens.…”