A whole life cycle assessment on effects of waterborne PBDEs on gene expression profile along the brain-pituitary-gonad axis and in the liver of zebrafish

X. B. HAN, Elva N. Y. LEI, Michael H. W. LAM, Shiu Sun Rudolf WU

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Abstract

Polybrominated diphenyl ethers (PBDEs) are now found ubiquitously in the aquatic environment and biota, and there is a growing concern that PBDEs may disrupt endocrine systems, leading to reproductive impairments of aquatic animals. In our study, zebrafish (Danio rerio) were exposed to the 5. ng/L, 1. μg/L and 50. μg/L of DE-71 for the duration of the whole life cycle (120. days, from eggs to adults). The expression of selected genes along the brain-pituitary-gonadal (BPG) axis and liver, and the levels of plasma sex hormones were examined.In male fish, up-regulation of GnRH in brain, FSHβ and LHβ in pituitary, FSH-receptor, LH-receptor, and CYP19a in testis was clearly evident, while down-regulation of CYP11a and 3β-HSD was found in testis. In female fish, a 2.4-fold up-regulation of 3β-HSD was found in ovary upon exposure to 50. μg/L of DE-71. GnRH in brain, FSHβ and LHβ in pituitary were also up-regulated, while ERβ, TH and TPH in brain and GnRH-receptor in pituitary were significantly down-regulated. Hepatic ERα, AR and VTG in males were all down-regulated, while hepatic ERα and AR in female were up-regulated.Serum estradiol (E2) was reduced in both male and female upon exposure to DE-71, while significant increases in serum testosterone (T) and 11-keto-testosterone (11-KT) were only found in male but not female fish. The ratio of T/E2 as well as the ratio of 11-KT/E2 in male fish increased in a dose-dependent manner upon exposure to DE-71. Our overall results showed that whole life exposure of DE-71 altered the expression of regulatory genes and receptors at all three levels of the BPG axis in zebrafish, and the responses are sex dependent. The observed disruption of GnRH and GtHs can be further related to the subsequent disruption in both levels and balance sex steroid hormones. Copyright © 2011 Elsevier Ltd. All rights reserved.

Original languageEnglish
Pages (from-to)160-165
JournalMarine Pollution Bulletin
Volume63
Issue number5-12
DOIs
Publication statusPublished - 2011

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polybrominated diphenyl ethers
life cycle assessment
PBDE
Danio rerio
Gene expression
Liver
gene expression
gonads
brain
Life cycle
Ethers
Brain
life cycle
Fish
testosterone
liver
receptors
sex hormones
fish
serum

Bibliographical note

Han, X. B., Lei, E. N. Y., Lam, M. H. W., & Wu, R. S. S. (2011). A whole life cycle assessment on effects of waterborne PBDEs on gene expression profile along the brain-pituitary-gonad axis and in the liver of zebrafish. Marine Pollution Bulletin, 63(5-12), 160-165. doi: 10.1016/j.marpolbul.2011.04.001

Keywords

  • PBDEs
  • Endocrine disruption
  • BPG axis
  • Steroidogenic genes
  • Reproduction
  • Zebrafish