Heart Malformation is an Early Response to TCDD in Embryonic Zebrafish

Antkiewicz, D.S., Burns, C.G., Carney, S.A., Peterson, R.E., and Heideman, W.
Toxicological sciences : an official journal of the Society of Toxicology   84(2): 368-377 (Journal)
Registered Authors
Burns, Geoff, Carney, Sara A., Heideman, Warren, Peterson, Richard E.
2,3,7,8-tetrachlorodibenzo-p-dioxin; TCDD toxicity; zebrafish; heart; development
MeSH Terms
  • Abnormalities, Drug-Induced/etiology*
  • Abnormalities, Drug-Induced/pathology
  • Animals
  • Cardiac Myosins/metabolism
  • Cell Count
  • Disease Models, Animal
  • Embryo, Nonmammalian/drug effects*
  • Embryo, Nonmammalian/embryology
  • Embryo, Nonmammalian/metabolism
  • Embryonic Development/drug effects*
  • Embryonic Development/physiology
  • Environmental Pollutants/toxicity*
  • Fluorescent Antibody Technique, Indirect
  • Heart Defects, Congenital/chemically induced*
  • Heart Defects, Congenital/pathology
  • Heart Rate/drug effects
  • Myocardium/metabolism
  • Myocardium/pathology
  • Myocytes, Cardiac/drug effects
  • Myocytes, Cardiac/pathology
  • Myosin Heavy Chains/metabolism
  • Teratogens/toxicity*
  • Zebrafish/physiology*
15635151 Full text @ Toxicol. Sci.
The zebrafish (Danio rerio) has become an attractive vertebrate model for studying developmental processes, and is emerging as a model system for studying the mechanisms by which toxic compounds perturb normal development. When exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) shortly after fertilization, zebrafish embryos exhibit pericardial edema and reduced blood flow by 72 hours post fertilization (hpf). To better understand the progression of dioxin toxicity in zebrafish, we have examined the effects of TCDD on heart development. At 72 hpf, TCDD-treated embryos exhibited altered looping, with the atria positioned distinctly posterior to the ventricles, contrary to the looping of control hearts, where the two chambers lied side by side. Moreover, the ventricles in dioxin-exposed hearts became more compact, and the atria elongated in comparison to controls. These defects are not secondary to pericardial edema because they were observed when edema formation was suppressed with osmotic support. In addition to morphological changes, TCDD produced functional deficits in the developing hearts, including blood regurgitation and a striking ventricular standstill that became prevalent by 120 hpf. We also assessed the effect of TCDD on the heart size using stereological measurements, which demonstrated significant reduction in heart tissue volume at 72 hpf. Perhaps our most significant finding was a decrease in the total number of cardiomyocytes in TCDD-exposed embryos by 48 hpf, 1 day prior to observable effects on peripheral blood flow. We conclude that the developing heart is an important target for TCDD in zebrafish.
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