ABSTRACT
Zebrafish (Danio rerio) is an increasingly popular vertebrate model used for assessing the toxicity of endocrine-disrupting chemicals (EDCs) on living beings. The zebrafish features high genetic homology to mammals, because of its rapid embryonic development, optical transparency of phenotypic screening embryos, high throughput genetic and chemical screening which make them a powerful toxicological model. This systematic review aimed to assess the recent literature on the use of zebrafish model in EDCs toxicity studies. We capture the data on the types of EDCs used, zebrafish life stages associated with the toxicity, and its effects on the alterations in neuroendocrine factors and cardiac hypoxia in zebrafish. A total of 17 articles published between 2010 and 2020 were curated. The information gathered highlighted the association of EDCs with cardiological outcomes and neurobehavioral effects and distorted expression of genes. The genes that were highlighted in the paper include bdnf, ntrk2a, grin2cb, VTG-1, HIF-1α, tnnt2, ntrk1, and pax6b. The effect of EDCs on cardiac hypoxia and neurodevelopmental and behavioral factors of zebrafish were described in all the papers chosen for this review. The involvement of EDCs in altered regulation of gene expression can be studied further to identify the potential EDC compounds on its toxicological and endocrine disruption function at the molecular level.
Subject(s)
Endocrine Disruptors , Zebrafish , Animals , Brain-Derived Neurotrophic Factor/metabolism , Embryonic Development , Endocrine Disruptors/metabolism , Endocrine Disruptors/toxicity , Hypoxia , MammalsABSTRACT
BACKGROUND: Endocrine-disrupting chemicals have been shown to cause toxicity in different systems of the body including the endocrine, cardiovascular and nervous systems. This study aims to analyze the adverse effects of Methylparaben (MP) on cardiac functions, neurodevelopment, and behavior of zebrafish. METHODS AND RESULTS: Adult male and female zebrafish were exposed to MP for 30 days to study the toxicity effects. Zebrafish were grouped into control, solvent control, 1/10th (110 ppb), 1/100th, and 1/1000th (1 ppb) lethal concentration 50 of MP. Neurobehavioral assays, acetylcholinesterase (AChE) activity, serotonin levels, and expression of genes-Hypoxia-inducible factor 1 alpha, Neurotrophic Receptor Tyrosine Kinase, Paired box protein Pax-6, and tnnt2 were investigated in zebrafish. Results of the study showed more anxiety-like behavior in MP-treated female zebrafish when compared to males on chronic exposure. There was a dose-dependent reduction of AChE activity in both male and female zebrafish. Female zebrafish showed a dose-dependent increase in serotonin level on MP exposure while male zebrafish showed a dose-independent decrease in serotonin level. On MP exposure, there was also a dose-dependent dysregulation in the expression of cardiac hypoxia and neuronal differentiation-related genes in female zebrafish while a dose-independent change was observed in male zebrafish. CONCLUSION: Chronic MP exposure affects cardiac functions, neuronal functions, and behavior of zebrafish by exhibiting changes in AChE activity, serotonin levels, and altering the expression of genes related to cardiac hypoxia and neuronal differentiation even at sub-lethal doses.