Abstract: The aim of this work is to investigate the deleterious effects of norfloxacin on zebrafish embryonic development in different periods, and determine its effects on TGF-β1 expression. Zebrafish embryos were exposed to different concentrations of norfloxacin(0, 10, 20, and 40 μmol/L). The effects of norfloxacin on spinal curvature, pericardial cyst, yolk edema and mortality of zebrafishes in the different developmental periods were observed. Furthermore, the mRNA level of TGF-β1 was examined by qPCR. The results showed that norfloxacin had significantly deleterious effects on zebrafish embryonic development, as mainly evidenced by spinal curvature, pericardial cyst and yolk edema. With the increase of concentration of norfloxacin, embryonic development was delayed, and the hatch period and mortality increased. The mortality rate of zebrafish embryos at 96 hpf re ached 76.46% after exposure to 40 μmol/L norfloxacin. Moreover, comparing with control group, the increase trend on mRNA level of TGF-β1 in zebrafish embryo exposing to different dose of norfloxacin slowed down with the prolonging of development time. Conclusively, norfloxacin has teratogenic and lethal effects on zebrafish embryonic development, suggesting norfloxacin residue in water system has serious latent dangers to the reproduction and development of fish.

Key words: norfloxacin, zebrafish, embryos, teratogenesis, lethal, TGF-β1