Effect and mechanism of zinc oxide nanoparticle on cardiac development of zebrafish embryos / 中国药理学与毒理学杂志

ABSTRACT

OBJECTIVE To explore the toxic effects of zinc oxide nanoparticls (ZnO-NPs) on cardiac development of zebrafish embryos and rat myocardial cell lines (H9c2),as well as potential molecular mechanisms.METHODS ZnO-NPs were characterized.Zebrafish embryos were exposed to different doses of ZnO-NPs (0,0.5,2.5,5.0 and 10.0 mg· L-1) for 24 to 96 h at 4 h post fertilization (4 hpf).The embryo mortality was observed.The expressions of notochord homeobox (noto),T-box 6 (tbx16),T,brachyury homolog a(ta),and tbx6 which were related to cardiac mesoderm were investigated using real-time PCR at 17 hpf.The heart rate and number of cardiomyocytes of embryos [[Tg (cmlc2nucdsRed)] exposed to 0,2.5 and 5 mg· L-1 ZnO-NPs were detected at 72 hpf.Rat myocardial cell lines (H9c2) were treated with ZnO-NPs (0.1,0.5,1.0,5.0 and 10.0 mg· L-1) for 24 h.Cell viability was measured with Alamar Blue method.Mitochondrial ultrastructure was observed by transmission electron microscopy.Cellular ATP was detected using chemiluminescence,and oxygen consumption rate (OCR) was examined with Seahorse instrument.RESULTS The particle size of ZnO-NPs was (331 ±3)nm.The ZnO-NPs LC50 of zebrafish embryos at 48 hpf was 21.81 mg· L-1.The mRNA expressions of noto,ta and tbx6 were reduced after ZnO-NPs 2.5 mg· L-1 treatment at 17 hpf.The heart rate of 72 hpf zebrafish was 153 min-1 in the ZnO-NPs 5 mg· L-1 group,12.6％ lower than that in the cell vehicle group (P＜0.01),and the number of cardiomyocytes decreased by 15.5％ (P＜0.01) compared with the cell vehicle group.Reduced cell viability and mitochondrial vacuolation were observed in H9c2 after ZnO-NPs 0.5 mg· L-1 exposure.Compared with the cell vehicle group,the cell ATP decreased by 25.7％ (P＜0.05),and OCR decreased by 27.2％ (P＜0.01).CONCLUSION Low-dose ZnO-NPs exposure has effect on the cardiac development of zebrafish,mainly due to reduced heart rate and decreased number of cardiomyocytes.These changes may be related to the decreased expressions of cardiac development-related genes and the impairment of mitochondrial structure and function.