Full sexual maturity-cycle exposure to environmentally relevant concentrations of 17β-estradiol decreases reproductive capacity of zebrafish

17β-Estradiol (E2) has been widely detected in natural water and treatment with E2 induces potential endocrine disrupting effects in fish. However, effects on fish fecundity and steroid system after treatment with environmentally relevant concentrations of E2 for the full sexual maturation cycle remain unclear. In this study, zebrafish were treatment with 0, 10 or 100 ng/L E2 from embryo to adult stage, and effects on gonadal development and differentiation, steroid hormone levels, transcription of genes associated with the hypothalamic-pituitary-gonadal-liver (HPG) axis in adults and fertilization rate of offspring were assessed. The results showed that treatment with E2 lead to increased number of feminization in zebrafish. In females, E2 decreased cumulative amount of spawning and inhibited the maturation of oocyte. In males, E2 inhibited the maturation and motility of sperm, as well as decreased the movement speed of sperm. These adverse effects on sperm might be responsible for the reduced fertilization observed in offspring. In addition, treatment with E2 changed the levels of steroid hormones in zebrafish gonad and altered the transcriptional levels of genes associated with HPG axis, which is responsible for the regulation of germ cells maturation and gonadal development in zebrafish. Overall, these results suggested that treatment with environmentally relevant concentrations of E2 for the full sexual maturity cycle resulted in adverse effects on reproduction in zebrafish.