Effects of tris(2-butoxyethyl) phosphate exposure on endocrine systems and reproduction of zebrafish (Danio rerio)

Tris(2-butoxyethyl) phosphate (TBEOP), a widely used organophosphate flame retardant, has frequently been detected both in the environment and the biota. However, limited information is available on the effects of TBEOP on the endocrine system and its underlying mechanisms. We exposed adult zebrafish pairs to TBEOP at concentrations of 0, 2.1, 11, and 118 μg/L for 21 d, and investigated the effects on gene transcription and hormone production related to the hypothalamic-pituitary-gonadal (HPG) axis, and on reproduction. The adverse effects on the F1 generation were further examined. In male fish, plasma concentrations of 17β-estradiol were significantly increased along with up-regulation of cyp19a. Exposure to TBEOP at 118 μg/L led to a significant decrease in average egg production. Exposure of the F0 generation to TBEOP delayed hatching and lowered hatching rates in the F1 generation. The results demonstrate that exposure to TBEOP at environmentally relevant concentration levels could affect the sex hormone balance by altering regulatory circuits of the HPG axis, eventually leading to disruption of reproductive performance and the development of offspring. [Display omitted] •TBEP increased the levels of E2 hormone and transcription of cyp19 gene in male zebrafish.•Changes in hormones and gene transcriptions of the HPG axis were sex-dependent.•Continuous exposure to TBEP impaired normal development in offspring generation. Our study demonstrates that TBEOP exposure at environmentally relevant concentrations causes hormonal and reproductive changes related to endocrine disruption in zebrafish.