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Updated: Nov 19, 2025
Studying Neurobehavioral Effects of Environmental Pollutants on Zebrafish Larvae
Published on: February 5, 2020
Ethinylestradiol (EE2) residues from birth control pills impair nervous system development and swimming behavior of
Ahmed Nasri1, Ali Mezni2, Pierre-André Lafon3
1Laboratory of Environment Biomonitoring, Unit of coastal Ecology and Ecotoxicology, Faculty of Sciences of Bizerte, University of Carthage, 7021, Zarzouna, Tunisia; U1198 MMDN (Molecular Mechanisms of Neurodegenerative Diseases), Inserm (National Institute for Health and Medical Research), MGX (Montpellier GenomiX), BioCampus, University of Montpellier, 34095, Montpellier, France.
Abstract:
The ubiquitous use of ethinylestradiol (EE2), an active constituent of birth control preparations, results in continuous release of this synthetic estrogen to surface waters. Many studies document the untoward effects of EE2 on the endocrine system of aquatic organisms. Effects of environmental EE2 on the nervous system are still poorly documented. We studied effects of pico- to nanomolar concentrations of EE2 on early nervous system development of zebrafish larvae. EE2 disrupted axonal nerve regeneration and hair cell regeneration up to 50%. Gene expression in larval brain tissues showed significantly upregulated expression of target genes, such as estrogen and progesterone receptors, and aromatase B. In contrast, downregulation of the tyrosine hydroxylase, involved in the synthesis of neurotransmitters, occurred concomitant with diminution of proliferating cells. Overall, the size of exposed fish larvae decreased by 25% and their swimming behavior was modified compared to non-treated larvae. EE2 interferes with nervous system development, both centrally and peripherally, with negative effects on regeneration and swimming behavior. Survival of fish and other aquatic species may be at risk in chronically EE2-contaminated environments.
