Epicardium Formation as a Sensor in Toxicology

Area of Science:

• Cardiovascular research
• Developmental biology
• Toxicology

Background:

• Zebrafish (Danio rerio) are a key vertebrate model for studying heart development, regeneration, and cardiotoxicity.
• The aryl hydrocarbon receptor (AHR) pathway plays a role in various biological processes.
• Epicardium development is crucial for heart formation and function.

Purpose of the Study:

• To investigate the impact of the AHR agonist 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on zebrafish heart development and regeneration.
• To determine if TCDD affects epicardium development and its role in cardiotoxicity.
• To explore the potential common mechanism underlying TCDD-induced cardiac defects and impaired regeneration.

Main Methods:

• Exposure of zebrafish embryos to TCDD during critical windows of epicardium development.
• Assessment of cardiac morphology and epicardium formation in TCDD-exposed embryos.
• Evaluation of cardiac regeneration in adult zebrafish following TCDD exposure and ventricular resection.

Main Results:

• TCDD exposure during early development prevents proepicardial organ and epicardium formation, leading to severe heart malformations.
• TCDD does not cause cardiac toxicity when exposure occurs after epicardium formation.
• Pre-exposure to TCDD inhibits cardiac regeneration in adult zebrafish after ventricular resection.

Conclusions:

• The epicardium is a critical target for TCDD-induced cardiotoxicity during zebrafish development.
• TCDD interferes with both epicardium development and cardiac regeneration, likely through a shared mechanism.
• Zebrafish serve as a valuable model for understanding how environmental toxins impact cardiac health and repair.