Effects of 17α-ethinylestradiol on the neuroendocrine gonadotropic system and behavior of European sea bass larvae (Dicentrarchus labrax)

ABSTRACT

The widespread use of 17α-ethinylestradiol (EE2), and other estrogenic endocrine disruptors, results in a continuous release of estrogenic compounds into aquatic environments. Xenoestrogens may interfere with the neuroendocrine system of aquatic organisms and may produce various adverse effects. The aim of the present study was to expose European sea bass larvae (Dicentrarchus labrax) to EE2 (0.5 and 50 nM) for 8 d and determine the expression levels of brain aromatase (cyp19a1b), gonadotropin-releasing hormones (gnrh1, gnrh2, gnrh3), kisspeptins (kiss1, kiss2) and estrogen receptors (esr1, esr2a, esr2b, gpera, gperb). Growth and behavior of larvae as evidenced by locomotor activity and anxiety-like behaviors were measured 8 d after EE2 treatment and a depuration period of 20 d. Exposure to 0.5 nM EE2 induced a significant increase in cyp19a1b expression levels, while upregulation of gnrh2, kiss1, and cyp19a1b expression was noted after 8 d at 50 nM EE2. Standard length at the end of the exposure phase was significantly lower in larvae exposed to 50 nM EE2 than in control; however, this effect was no longer observed after the depuration phase. The upregulation of gnrh2, kiss1, and cyp19a1b expression levels was found in conjunction with elevation in locomotor activity and anxiety-like behaviors in larvae. Behavioral alterations were still detected at the end of the depuration phase. Evidence indicates that the long-lasting effects of EE2 on behavior might impact normal development and subsequent fitness of exposed fish.

Acknowledgments

The authors thank the Normandie Region (program LITOTES), the institute IFREMER (program PENELOP) and the Interreg RedPol project (Reduction of Pollution by endocrine-disrupting compounds at source: innovative products for the commercial lab market) for their financial support. S.S is a recipient of a PhD grant from the urban community LHSM (Le Havre Seine Métropole).

Authors’ contributions

S.A. and S.S. designed the study; S.A., S.O. A.P., and S.A. carried out the experiment; S.S and C.J.A. performed data analyses; and S.S, MP.H.L, C.J.A, C.M and S.A. wrote or contributed to the writing of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

Raw data were generated at SEBIO. Derived data supporting the findings of this study are available from the corresponding author [S.A.] on request.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/15287394.2023.2177781

Ethics approval and consent to participate

All procedures were performed in accordance with the French and European legislation concerning the protection of animals used in experimentation. Procedures undertaken were approved (#10263–2017061911009684v3) by the regional ethical committee

Additional information

Funding

This work was supported by the Normandie Region (program LITOTES), the urban community Le Havre Seine Metropole, the IFREMER institute (program PENELOP) and the European Interreg RedPol project (Reduction of Pollution by endocrine disrupting compounds at source: innovative products for the commercial lab market).