Isoniazid causes heart looping disorder in zebrafish embryos by the induction of oxidative stress

Abstract Background: The cardiotoxicity of isoniazid on zebrafish embryos and its underlying mechanism is unclear. Methods: Here, we exposed zebrafish embryos at 4 hours post-fertilization to different levels of isoniazid and recorded the morphology and number of malformed and dead embryos under the microscope. Results: The high concentration of isoniazid group showed more malformed and dead embryos than the low concentration of isoniazid group and control group. The morphology of the heart and its alteration were visualized using transgenic zebrafish (cmlc2: GFP) and confirmed by in situ hybridization. The negative effects of isoniazid on the developing heart were characterized by lower heart rate and more heart looping disorders. Mechanistically, PCR showed decreased expression of heart-specific transcription factors when exposed to isoniazid. Oxidative stress was induced by isoniazid in cardiomyocytes, mediated by decreased activities of catalase and superoxide dismutase, which were rescued by scavengers of reactive oxygen species. Conclusion: In conclusion, this study demonstrated that isoniazid led to heart looping disturbance by the downregulation of cardiac-specific transcription factors and induction of cardiomyocyte apoptosis.