Toxic Effect Of Silica Nanoparticles On The Development Of Zebrafish Embryos And Larvae

Objective: The aim of this study is to evaluate the toxic effect of Silica nanoparticles on the development of Zebrafish embryo and larvae, and to reveal the target organ and potential molecular mechanisms.Methods: 1. Effect of Si NPs on Zebrafish embryos: Zebrafish embryos were exposed to Si NPs(37~ 1500 μg/ml), and the lethal effect, terotogenecity and developmental arrest or delay induced were evaluated, meanwhile, benchmark doses(BMD) of the indicators were calculated. 2. Effect of Si NPs on Zebrafish heart development: based on the BMDs of the above experiments, a series of doses(6~36μg/ml) were used to evaluate adverse effect of heart formation and function. In addition, the degree of myocardial apoptosis and expression of related genes on zebrafish embryo and larval were examed by Acridine Orange(AO) staining, TUNEL and q RT-PCR. 3. SPSS17.0 software was used for statistical analysis. The values were expressed as SX ±, and significant differences between control and treated groups were performed by using analysis of variance followed by Post hoc comparison. Differences were set at P-values less than 0.05(P < 0.05). Results: 1. Toxicity effect of Si NPs on zebrafish embryo development(1) Malformation was caused by exposed to Si NPs in a dose- and time- dependent manner(EC50=449μg/ml). This study showed that several types of malformation in embryos exposed to Si NPs, including pericardial edema, yolk sac edema, tail and head malformation. The pericardial edema occurred as the commonest form of malformations observed in embryos exposed to Si NPs.(2) Si NPs has a strong inhibit effects on zebrafish embryo development. The main perform was inhibition of hatching rate, prolonged hatching period, reducing the absorption rate of the yolk and body length.(3) The mortality of zebrafish embryo caused by Si NPs was perform in a dose- and time- dependent manner(LC50=1236μg/ml).(4) The BMDL for the alterations described previously were as follows: BMDL malformation=2.43μg/ml, BMDLhatch=14.79μg/ml, BMDLmortality=18.62μg/ml. 2. Effect of Si NPs on zebrafish embryo heart development(1) It was found that exposure to Si NPs increased the distance between SV-BA, the pericardial area and the prevalence of pericardial edema. And the BMDL for cardiac malformation was 10.19μg/ml.(2) Exposed to silica nanoparticles caused embryo tachycardia and arrhythmias, indicating that silica nanoparticles could affect cardiac function of zebrafish.(3) The cardiac tissue slices stained with HE showed decreased number of myocardial cells, irregularity and partial dislocation of cell arrangement.(4) The results of Acridine Orange(AO) and TUNEL staining showed that silica nanoparticles could promote the cell apoptosis.(5) Si NPs exposure would induce a pro-apoptotic response through up-regulation of P53 gene in the embryonic cells to disturb the heart formation and development of zebrafish embryos. Conclusions: 1. Exposure to Si NPs causes developmental toxicity of zebrafish embryos and larvae including that malformation, retardation and death. 2. Exposure to Si NPs increased the distance between SV-BA and the pericardial area, and caused embryo tachycardia and arrhythmias, indicating that silica nanoparticles could affect cardiac function of zebrafish. 3. Exposure to Si NPs induces excessive apoptosis of embryonic cells through activation of P53-mediated mitochondrial pathway which results in disformation and underdevelopment of heart.