Effects of Diethylstilbestrol on Zebrafish Gonad Development and Endocrine Disruption Mechanism

Environmental estrogen is a substance that functions as an endocrine hormone in organisms and can cause endocrine system disruption. A typical environmental estrogen, diethylstilbestrol (DES), can affect normal sexual function and organism development. However, even though the effects of different exposure stages of DES on the endocrine system and gonadal development of zebrafish juveniles are unknown, sex determination is strongly influenced by endocrine-disrupting chemicals (EDCs). From 10–90 days post fertilization (dpf), juvenile zebrafish were exposed to DES (100 and 1000 ng/L) in three different stages (initial development stage (IDS), 10–25 dpf; gonadal differentiation stage (GDS), 25–45 dpf and gonadal maturity stage (GMS), 45–60 dpf). Compared with that of IDS and GMS, the growth indicators (body length, body weight, and others) decreased significantly at GDS, and the proportion of zebrafish females exposed to 100 ng/L DES was significantly higher (by 59.65%) than that of the control; in addition, the zebrafish were biased towards female differentiation. The GDS is a critical period for sex differentiation. Our results show that exposure to environmental estrogen during the critical gonadal differentiation period not only affects the development of zebrafish, but also affects the population development.