Effects of 17α-ethynylestradiol on early-life development, sex differentiation and vitellogenin induction in mummichog (Fundulus heteroclitus)

Abstract

Fertilized mummichog eggs retrieved from 17alpha-ethynylestradiol (EE(2)) exposed adult fish were raised in concentrations of EE(2) ranging from 0 to 100 ng/L (100 ng/L EE(2) estimated to have actual average exposure concentrations of 30% of nominal; 0.1-10 ng/L were below detect throughout 24-h exposure period) for 61 weeks post-hatch. Eggs exposed at 100 ng/L hatched sooner, the larvae were longer, and survival of juvenile fish from hatch to study termination was greater than all other treatments, though fewer hatched at this treatment. Sex ratios were skewed (>80% female phenotype) at 100 ng/L EE(2), and some gonadal male fish displayed female secondary sex characteristics. Condition factor, gonadosomatic index (GSI), and liver somatic index (LSI) were found to decrease in both sexes between 52 and 61 weeks post-hatch. Female fish had increased hepatic vitellogenin (VTG) at 52 weeks post-hatch. When exposed to 1, 10 and 100 ng/L EE(2), female fish had a higher proportion of vitellogenic follicles in the ovarian tissue. Males exposed at 100 ng/L may have had disruption at some endpoints (GSI, VTG) that is masked due to reduced sample size compared to other treatments. Fish exposed to concentrations of EE(2) at or below 10 ng/L showed inconsistent effects on development and reproductive potential. This study indicates the potential for population-level effects at the high range of environmental EE(2) at concentrations equivalent to those at which consistent effects in fecundity in the adult mummichog reproductive test have been measured. This work demonstrates that chronic EE(2) exposure causes developmental effects at concentrations similar to those which cause effects in the shorter-term adult mummichog reproductive test. Effects are at higher concentrations than have been noted for freshwater model species. Whether this is because of species sensitivity or due to differences between freshwater and saltwater availability of EE(2) or its uptake requires further study.

An approach to detecting estrogenic endocrine disruption via choriogenin expression in an estuarine model fish species

“…This is particularly useful in light of the heightened sensitivity of juvenile fish to EDCs (Jin et al 2010;Peters et al 2009). Using silversides as a surrogate for examining the impact of endocrine disruption in North American estuaries is supported by of the high sensitivity of juveniles to ethinylestradiol (EE2) in this study.…”

“…An alternative to using plasma is to instead use whole body homogenate (WBH). This enables the inclusion of juveniles, which are more sensitive to EDCs than adults (Peters et al 2009). Although WBH is a complex matrix, it can be successfully used in conjunction with a highly specific antibody (Holbech et al 2001).…”

The in vivo estrogenic and in vitro anti‐estrogenic activity of permethrin and bifenthrin

“…has been shown to be susceptible to estrogen exposure during the larval period [36]. Notably, our study is the first to look at protein-level endocrine disrupting effects of pyrethroids on juvenile fishes, which are more sensitive to such environmental EDC perturbations than adults [14] and more likely to experience long-term developmental changes such as reduced fecundity and/or intersex when exposed to EDCs [37]. …”

A review of studies on androgen and estrogen exposure in fish early life stages: effects on gene and hormonal control of sexual differentiation

“…When environmental exposure to hormones is in mixtures, which is the case more often than not, effects like inhibited reproduction and growth are also seen (Jobling et al , ; Peters et al , ). Although many environmental factors (most notably temperature) can contribute to changes in growth, reproductive condition and sex ratios, many of the studies discussed here provide evidence that these may also be seen as signs of hormone exposure.…”