Early-life exposure to di(2-ethylhexyl) phthalate impairs reproduction in adult female zebrafish (Danio rerio)

Abstract

Di(2-ethylhexyl) phthalate (DEHP) is a plasticizer used in various industrial and consumer products. It is not covalently bound within these products and leaches out during repeated use, heating, or cleaning. Main routes of environmental DEHP pollution are through the industrial and municipal wastewaters, which pollute aquatic environments. The reproductive system of adult fish is known to be vulnerable to DEHP exposure; however, the effects of early-life exposure to DEHP on reproductive function in adult zebrafish (Danio rerio) females are less studied. To evaluate the impact of early-life exposure to DEHP on freshwater female fish reproduction, zebrafish embryos were exposed to DEHP at 0, 10, 100, and 1000 nmol/L from 5 h post-fertilization (hpf) to 120 hpf (larval stage) and then raised to adulthood in clean water. DEHP decreased the number of released eggs and the fertilization rate after mating with unexposed males. Body weight and length, the weight of the ovaries, and the gonadosomatic index were decreased in adult female zebrafish following early-life exposure to DEHP. Histological analysis of the ovaries revealed that DEHP inhibited oogenesis. Serum 17β-estradiol levels were significantly reduced. DEHP inhibited gene expression of all three nuclear estrogen receptors in the ovaries, namely esr1, esr2a, and esr2b, and two gonadotropin receptors, fshr and lhr. These results suggest that transient early-life exposure to environmentally relevant concentrations of DEHP can inhibit the reproduction of adult female zebrafish.