An In Vitro and In Vivo Study of Thyroid Disruption of 1,2-Bis(2,4,6-tribromophenoxy)ethane (BTBPE)─A Novel Brominated Flame Retardant

Abstract

The novel brominated flame retardant, 1,2-bis-(2,4,6-tribromophenoxy)ethane (BTBPE), is an emerging environmental pollutant with undetermined toxicity. We investigated how BTBPE causes thyroid endocrine disruption with integrated in silico, in vitro, and in vivo assays. In yeast two-hybrid and T-Screen assays, BTBPE interacted with zebrafish thyroid hormone receptors with binding energies weaker than the TR agonist-3,3′,5-Triiodo-L-thyronine (T3), and disrupted thyroid function as a thyroid receptor (TR) agonist. We examined the bioconcentration, developmental toxicity, and thyroid endocrine disruption in zebrafish after a 14-day exposure to BTBPE (1, 3, 10 μg/L). Thyroxine (T4) was lower in BTBPE-treated larvae, whereas corticotropin-releasing hormone (CRH) and thyroid-stimulating hormone (TSH) were higher. The gene transcription alterations along the hypothalamic-pituitary-thyroid (HPT) axis were observed. Furthermore, reduced locomotion suggested that BTBPE imparts developmental neurotoxicity at zebrafish early developmental stage. Establishing that BTBPE has thyroid endocrine-disrupting effects is an important step for understanding and managing BTBPE toxicity.

Bis(2-ethylhexyl)-2,3,4,5-tetrabromophthalate Enhances foxo1-Mediated Lipophagy to Remodel Lipid Metabolism in Zebrafish Liver

“…Both wild-type (AB strain) and transgenic zebrafish Tg (Apo14: GFP) were obtained from the China Zebrafish Resource Center (Wuhan, China). The zebrafish maintenance was performed following a previously described protocol . Randomly selected zebrafish embryos (0.75 hpf) were maintained in a 14:10 light–dark cycle at a constant temperature of 28 ± 0.5 °C.…”

“…The zebrafish maintenance was performed following a previously described protocol. 29 Randomly selected zebrafish embryos (0.75 hpf) were maintained in a 14:10 light−dark cycle at a constant temperature of 28 ± 0.5 °C. All experiments involving zebrafish were performed according to the Zebrafish Usage Guidelines of the China Zebrafish Resource Center with the approval of the Institutional Animal Care and Use Committee of the Institute of Hydrobiology, Chinese Academy of Sciences (IHB/LL/2021016).…”

Mechanistic Insights into 1,2-bis(2,4,6-tribromophenoxy)ethane-Induced Male Reproductive Toxicity in Zebrafish

“…The concentration of BTBPE in the exposure solution was determined utilizing a GC-MS system (Agilent 7890B-7000c; Agilent Technologies, CA, USA) as previously described . Immediately after refreshing the exposure solution, 1 L water samples were collected, ensuring triplicate samples for each group.…”