Thyroid Disruption in Zebrafish Larvae by Short-Term Exposure to Bisphenol AF.

Tianle Tang,Fuqiang Wang,Wenhao Tang,Xiaoping Diao,Yang Yang,Yawen Chen

doi:10.3390/ijerph121013069

Abstract

Bisphenol AF (BPAF) is extensively used as a raw material in industry, resulting in its widespread distribution in the aqueous environment. However, the effect of BPAF on the hypothalamic-pituitary-thyroidal (HPT) axis remains unknown. For elucidating the disruptive effects of BPAF on thyroid function and expression of the representative genes along the HPT axis in zebrafish (Danio rerio) embryos, whole-body total 3,3′,5-triiodothyronine (TT3), total 3,5,3′,5′-tetraiodothyronine (TT4), free 3,3′,5-triiodothyronine (FT3) and free 3,5,3′,5′-tetraiodothyronine (FT4) levels were examined following 168 h post-fertilization exposure to different BPAF concentrations (0, 5, 50 and 500 μg/L). The results showed that whole-body TT3, TT4, FT3 and FT4 contents decreased significantly with the BPAF treatment, indicating an endocrine disruption of thyroid. The expression of thyroid-stimulating hormone-β and thyroglobulin genes increased after exposing to 50 μg/L BPAF in seven-day-old larvae. The expressions of thyronine deiodinases type 1, type 2 and transthyretin mRNAs were also significantly up-regulated, which were possibly associated with a deterioration of thyroid function. However, slc5a5 gene transcription was significantly down-regulated at 50 μg/L and 500 μg/L BPAF exposure. Furthermore, trα and trβ genes were down-regulated transcriptionally after BPAF exposure. It demonstrates that BPAF exposure triggered thyroid endocrine toxicity by altering the whole-body contents of thyroid hormones and changing the transcription of the genes involved in the HPT axis in zebrafish larvae.

Highlights

Bisphenol AF (BPAF, 1,1,1,3,3,3-hexafluoro-2,2-bis(4-hydroxyphenyl)propane), is a derivative of bisphenol A (BPA) in which the (–CH3) groups are replaced by (–CF3) groups
No significant effects were observed with survival, length, weight after exposure to BPAF (SC, 5, 50, and 500 μg/L) from being hatched to 168 hpf
Previous studies showed that other bisphenol analogues, such as bisphenol F, tetrabromobisphenol A (TBBPA), and bisphenol B, may have similar endocrine-disrupting effects based on their structural similarity with BPA

Summary

Introduction

Bisphenol AF (BPAF, 1,1,1,3,3,3-hexafluoro-2,2-bis(4-hydroxyphenyl)propane), is a derivative of bisphenol A (BPA) in which the (–CH3) groups are replaced by (–CF3) groups. It is one of the high-yielding raw materials used in fluoroelastomers and polyesters [1,2,3]. BPAF has been detected at a concentration of 1.53 × 104 ng/L in water and 2.00 × 103 ng/g (dry weight) in sediments which were sampled from a river near a factory in China [4]. The BPAF detection ratio was nearly half (24/52) in 52 samples collected from 30 urban sewage treatment plants in China, and the highest concentration detected was 45.1 ng/g (dry weight) [5]

Results

Discussion

Conclusion