Toxic effect of di(2-ethylhexyl)-phthalate on zebrafish heart development

Abstract

Objective To determine the toxicity of the di(2-ethylhexyl)-phthalate(DEHP) on early development of zebrafish(danio rerio) embryos and to explore its mechanism during this procedure. Methods The fertilized embryos of zebrafish were divided into 6 groups: 4 groups of them were exposed to different concentrations of DEHP(1, 2, 4, 8 mg/L), while 2 other groups were treated with 79.2 mg/L methanol and 60 mg/L sodium chloride solution respectively as controls.To investigate the interaction between DEHP and early zebrafish embryonic development, the rate of hatching, malformation and lethality of embryos were studied from different DEHP-exposed and control groups.And to gain insight into the mechanisms underlying DEHP function in early zebrafish cardiac development, in situ hybridization for early cardiac molecular markers were performed. Results By carefully collecting and studying the results of DEHP-treated and control embryos, the rates of malformation of embryos and lethality of larvae were increased in a dose-dependent way, coupled with decreased hatching rate of embryos at 72 hpf.When the concentration of DEHP reached 8 mg/L, the hatching rate of embryo at 72 hpf was reduced to 62.22%, the malformation rate of embryo was increased to 27.30%, and the lethality rate of larvae at 120 hpf reached 40.00%.Expression of cardiac specific gene, indicated by using in situ hybridization, showed that heart position and heart tube looping of zebrafish embryos from DEHP-treated groups were strongly affected.Compared with control embryos, the expression of atrial myosin heavy chain(amhc), ventricular myosin heavy chain(vmhc) and cardiac myosin light chains(cmlc2) had been changed in the DEHP-treated groups at 24 hpf and 48 hpf. Conclusions DEHP could impact the development of zebrafish heart, and further lead to the malformation of zebrafish embryo and death of larvae.And the toxic effect of DEHP on zebrafish heart development may occur in the progress of heart tube looping. Key words: Zebrafish; Di(2-ethylhexyl)-phthalate; Heart development; Embryo toxicity