Exposição embrionária a genisteína induz comportamento ansiolítico e antissocial em zebrafish: efeitos persistentes até a fase adulta

Abstract

Genistein is a phytoestrogen present in several food and in bigger abundance in soybean and its derivatives. It has a chemical structure similar to 17𝛽-estradiol and has the ability to bind to the same receptors, triggering estrogenic or antiestrogenic action depending on the target tissue, concentration of endogenous estrogens and number of free receptors. Because it is an endocrine disrupting substance, it may cause damage to the reproductive system, both in humans and animals. The main objective of this work was to elucidate the effects that genistein, in similar concentrations found in effluents, causes in behavior and sexual differentiation of fish exposed during the embryonic period. The effects of embryonic exposure were evaluated in the larval stage and in adult stage. Zebrafish eggs were exposed during the first 72 hours post-fertilization (hpf) to 3 different concentrations of genistein: 10μg/L, 40μg/L e 80μg/L. At 48hpf, the heart rate was checked (BPM) and during the first 72hpf, the mortality rate was performed. The light/dark and open field behavioral test were applied to the larvae at 6 day post-fertilization (dpf), and the novel tank, social preference and light/dark tests to adult fish at 90dpf. Sexing was performed after conducting behavioral tests (90dpf). Embryonic exposure to genistein caused anxiolytic-like behavior both in larvae and in adult stages. In adult stages, we observed an increasing in locomotor activity and antisocial behavior in concentration of 40μg/L. There was an increase in mortality rate, in concentrations of 10, 40 and 80μg/L when compared to the control and there was an increase in heart rate at the dosage of 80μg/L. Exposure to 10μg/L presented a higher rate in females when compared to the rate found in controls. Our results show that exposure to genistein during embryonic phase brings short and long term damages as it increases mortality rate and leads to behavioral disorder both in the larval and adult stages. The anxiolytic-like effect and less social interaction are effects that harm survival, due to the loss of notion of predator, affecting social performance and, therefore, the search for food and the reproduction of fish.