The objective of this study was to evaluate the toxic effects of progesterone (PF) and estradiol (EF) and the effect of these steroid hormones complexed into cyclodextrins, commercially available drugs, such as micronized progesterone (PM) and transdermal estradiol (ET), and evaluate them as endocrine disruptors through biological parameters of Danio rerio. An acute toxicity test was performed with hormones using D. rerio embryos according to OECD 236 guidelines. The heart rate, mortality, and teratogenic effects were evaluated. In addition, a chronic toxicity test was assayed with adult animals for evaluation of animal behavior, reproductive capacity, and electrophysiological responses of the retina. Analysis of the results of the acute toxicity test with embryos exposed to progestins and estrogens showed that free hormones caused a higher percentage of teratogenic effects such as pericardial edema, yolk sac edema, and spinal deformation. Behavioral evaluation (30-60 days) of adult animals exposed to PM, EF, and ET demonstrated higher frequencies of aggressive behaviors such as Chase away, Persecution, Escape, and Attack. Analysis of reproductive capacity did not show significant differences in the number of viable eggs, and no significant changes were observed in the electrophysiological responses of the retina. According to these results, there is a higher toxicity effect of hormones in the free form when compared to the commercial forms and inclusion complexes. This indicates that complexation into cyclodextrin reduced the toxicity of the hormones according to the parameters studied.
RESUMO Foram avaliados os efeitos tóxicos do hormônio 17β-estradiol (E2) livre e complexado à β-ciclodextrina (CD) sobre o comportamento e a fisiologia de tilápia (Oreochromis niloticus). Os peixes foram observados por 30 dias, em dois estágios do desenvolvimento (alevino e juvenil), pelo método ad libitum, para a confecção de um etograma. Posteriormente, juvenis foram divididos em três grupos: controle e expostos ao E2 (10ng/L) livre e complexado à β-ciclodextrina (β-CD:E2) por 90 dias. Foram avaliados o comportamento pelo método de varredura instantânea, o consumo de ração, o ganho de peso e a mortalidade em diferentes intervalos. Os alevinos e os juvenis apresentaram frequências de exibição comportamentais diferentes (P<0,05) nos eventos: Afastar (4,7±1,3 e 3,6±0,6%) e Ondulação de repulsão (2,3±0,9 e 1,3±1,0%). Os juvenis expostos ao complexo β-CD:E2 apresentaram aumento (P<0,05) na exibição dos comportamentos agressivos, como Afastar, Ataque caudal, Confronto prolongado, Perseguição, Fuga, e menor mortalidade, quando comparados ao grupo exposto ao E2 livre e controle. Pode-se concluir que a complexação do E2 com a β-CD alterou a toxicidade do E2, pois promoveu um aumento na frequência de exibição dos comportamentos agressivos e interferiu na mortalidade dos animais.
In this study, the effects of exposure to rotenone on development were evaluated, particularly teratogenic and behavioral endpoints in the early life stages of zebrafish. This can serve as a model for Parkinson-like motor and non-motor symptoms, and anxiety-like behavior. The endpoints of percent epiboly, teratogenic effects, mortality, morphometry, thigmotaxis (TH), touch sensitivity (TS), and optomotor response (OMR) were analyzed in zebrafish embryo-larvae stage exposed to rotenone (5 to 20 µg/L). An increase in mortality of zebrafish was observed at 15 and 20 µg/L rotenone concentrations. The rotenone reduced the percent epiboly and increased the presence of teratogenic effects at concentrations of 10, 15, and 20 µg/L. Head and body size reductions were observed at all rotenone concentrations tested. Anxiety-like behaviors were observed with decreased displays of TH behavior in larvae exposed to 15 and 20 µg/L of rotenone. TS was reduced by 20 µg/L rotenone treatment. OMR and the eye diameter of zebrafish were not affected by rotenone exposure. Our results showed that rotenone has the potential to provoke non-motor symptoms, mainly anxiety-like behaviors, in the zebrafish's early life stages, making it a potential model for the study of Parkinson-like disease.
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