The effects of ethinylestradiol (EE2) on molecular signalling cascades in mummichog (Fundulus heteroclitus)
University of New Brunswick
Exposures to ≤10 ng/L of 17 α-ethinylestradiol (EE2), a synthetic estrogen used in birth control pills, will reduce or shutdown egg production in freshwater fish models, while mummichog (Fundulus heteroclitus), an estuarine species, are able to produce eggs at EE2 concentrations of >3000 ng/L. The objective of this research was to gain mechanistic insights into how mummichogs are able to produce eggs at high EE2 exposures. Mummichog were exposed to 0, 50 or 250 ng/L of EE2 for 14 d. There were no differences in gonadosomatic index, liversomatic index, gonad development, or plasma estradiol levels. However, testosterone decreased with increasing EE2 concentrations (50, 250 ng/L). Microarray analysis of liver tissue revealed that cell processes associated with apoptosis, lipids, and translation were affected by EE2. Transcriptomics data are comparable to other fish studies and the liver appears to be under generalized stress from EE2 exposure. This study suggests that mummichog are able to maintain lipid/vitellogenin uptake by the ovary despite exposure to EE2, while other species are unable to do so.