Endocrine Disrupting And Mechanism Of CuO Nanoparticles On The Reproductive System And Thyroid System Of Zebrafish

While expectations and applications of nanotechnology grow exponentially,little is known about the interactions of engineered nanoparticles with multicellular organisms.Research on the toxicity of nanomaterials and their impact on the environment becomes increasingly imperative,such as degradability of nanomaterials in nature environment,the degree of nanomaterial accumulation in organisms,enrichment in the ecosystem,toxic effects and mechanisms of different organisms in ecosystems.In recent years,reports on cytotoxicity,genotoxicity,embryonic toxicity and the effects on plants of copper oxide nanoparticles have been increasing.However,there are relatively few studies about copper oxide nanoparticles on the reproduction and thyroid system of zebrafish.Therefore,in this study we selected adultfish and larve as a model animal,to analyze systematically the interference effect and mechanism of copper oxide nanoparticles on the reproductive system and thyroid system of zebrafish.The following is the result of the study:1?In the acute toxicity test of CuO NPs to embryos,CuO NPs can affect the survival of embryos and delay the hatching of embryos,causing malformation such as pericardial edema,delayed absorption of yolk sac and somites.2?After exposure to 10,50,and 100 ?g/L CuO NPs for 10 and 20 days,there were changes in a series of reproductive indices.Such as the estradiol levels in both females and males were increased,and while the testosterone levels were decreased.Histopathological observations demonstrated that zebrafish ovary and testis suffered serious damage after CuO NPs-exposure as well as the alter of genes expression.For example,the estrogen receptor genes(er??er2?)were up-regulated and the androgen receptor was down-regulated.Therefore the results suggest that the adult zebrafish exposed to different concentrations of CuO NPs will lead to imbalance in sex hormone levels,damage of gonadal tissue,changes in hypothalamic-pituitary-gonadal axis gene expression thus indicating there is a disturbing effect of CuO NPs in the reproductive system of zebrafish.3?After exposure to 10,50,and 100 ?g/L CuO NPs for 10 and 20 days,the thyroid hormones in zebrafish larve were increased and the thyroid follicles were damaged.In the level of gene expression,the genes in the brain of zebrafish(crh?tsh)were disordered,the genes of the THs synthesis(nis?tg?tpo)were up-regulated,and the expression of the metabolic gene(ugt1ab)was decreased.Therefore the results suggest that the CuO NPs can affect the thyroid hormone levels,damage the thyroid gland,and interfere with the hypothalamus-pituitary-thyroid axis gene expression in juvenile zebrafish,resulting in abnormal physiology of the zebrafish thyroid.