Parental Transfer of Polybrominated Diphenyl Ethers (PBDEs) and Thyroid Endocrine Disruption in Zebrafish

Abstract

Polybrominated diphenyl ethers (PBDEs) have the potential to disrupt the thyroid endocrine system. The objective of the present study was to characterize the disrupting effects of longterm exposure on the thyroid endocrine system in adult fish and their progeny following parental exposure to PBDEs. Zebrafish (Danio rerio) embryos were exposed to environmentally relevant concentrations (1, 3, and 10 μg/L) of the PBDE mixture DE-71 for 5 months until sexual maturation. In the F0 generation, exposure to DE-71 significantly increased plasma thyroxine (T4) but not 3,5,3 0 -triiodothyronine (T3) in females. This increased T4 was accompanied by decreased mRNA levels of corticotropinreleasing hormone (CRH) and thyrotropin β-subunit (TSHβ) in the brain. The F1 generation was further examined with or without continued DE-71 treatment conditions. Exposure to DE-71 in the F0 fish caused significant increases in T4 and T3 levels in the F1 larvae and modified gene expressions in the hypothalamicÀ pituitaryÀthyroid axis (HPT axis) under both conditions. Decreased hatching and inhibition of growth in the F1 offspring were observed in the condition without DE-71 treatment. Continued DE-71 treatment in the F1 embryos/larvae resulted in further decreased hatching, and increased malformation rates compared with those without DE-71 exposure. Analysis of F1 eggs indicated that parental exposure to DE-71 could result in a transfer of PBDEs and thyroid hormones (THs) to their offspring. For the first time, we demonstrated that parental exposure to low concentrations of PBDEs could affect THs in the offspring and the transgenerational PBDE-induced toxicity in subsequent nonexposed generations.

Prenatal Transfer of Polybrominated Diphenyl Ethers (PBDEs) Results in Developmental Neurotoxicity in Zebrafish Larvae

“…12 Our previous study demonstrated that 150 days of exposing zebrafish embryos to DE-71 (1, 3, 10 μg/L) can elevate TH levels in adults and that increased TH levels are also transferred to F1 eggs. 6 In the present study, our results showed again that significant levels of DE-71 are transferred from exposed adult fish to their offspring, resulting in an increased prevalence of impaired health in the offspring. A 21-day dietary PBDE-47 treatment (2.4 or 12.3 μg/pair/day) in adult fathead minnows (Pimephales promelas) resulted in depressed plasma thyroxine (T4) and changed brain mRNA levels of THresponsive genes.…”

“…The detection limit was calculated as three times the procedural blank (0.1 ng/g for tetra-BDE, 0.05 ng/g for tri-and penta-to hepta-BDEs). 6,31 Statistical Analysis. All data are expressed as the mean ± standard error (SEM).…”

“…In fish, the maternal transfer of PBDEs has previously been observed after dietary PBDE exposure, 4,5 and via water in laboratory conditions. 6 It has also been detected in striped bass (Morone saxatilis) eggs (100−150 ppb) in the San Francisco estuary. 7 This transfer of PBDEs from parents could interfere with developmental effects on the progeny.…”

Sex-dependent accumulation and maternal transfer of Dechlorane Plus flame retardant in fish from an electronic waste recycling site in South China

“…Early life stages of many oviparous species exhibit the greatest toxicological sensitivity to organic contaminants, and various organochlorine compounds have been shown to cause embryotoxic effects in fish (Henry et al, 1997;Westerlund et al, 1999;Wassenberg and Di Giulio, 2004;Heiden et al, 2005). Maternal transfer of various lipophilic organic chemicals such as polychlorinated biphenyls (PCBs) and PBDEs in fish has been observed both in laboratory experiments and field research (Miller, 1993;Russell et al, 1999;Heiden et al, 2005;Nyholm et al, 2008;Ostrach et al, 2008;Yu et al, 2011). Like PCBs and PBDEs, DP and its dechlorinated analogs are highly lipophilic.…”

Acute exposure to DE‐71: Effects on locomotor behavior and developmental neurotoxicity in zebrafish larvae

“…In fish, levels of PBDEs have been recorded in fish eggs, demonstrating that maternal transfer takes place and suggesting that offspring could be exposed to these compounds during embryogenesis, particularly the central nervous system [15][16][17][18]. Lema et al [19] reported that waterborne exposure of zebrafish embryos to BDE-47 resulted in reduced movement of cerebrospinal fluid in the brain ventricles and neural tubes in the larvae.…”