Zebrafish Model to Study Angiotensin II-Mediated Pathophysiology

SIMPLE SUMMARY: Hypertension or high blood pressure is a long-term incurable clinical condition characterized by persistent high blood pressure in arteries. Constant pressure overload in the heart leads to cardiac remodeling involving hypertrophy, alteration of gene expression, extracellular matrix molecule deposition, and cardiac fibrosis. In the long term, if left untreated, it can lead to myocardial infarction. Zebrafish is a freshwater fish that has been proven to be a very beneficial model system to study development, regeneration, and human diseases in recent years. We propose in this study zebrafish as a model to study Angiotensin II-mediated (AngII) multifactorial pathophysiology. AngII is an effector molecule of the Renin–Angiotensin system (RAS), which plays a crucial role in hypertension in mammals. In our study, AngII was injected at regular time intervals for a period of time. Our results show that, similar to mammals, AngII induces fibrotic gene expression, collagen deposition, cardiomyocyte hypertrophy, and cardiac cell proliferation. Thus, we propose that zebrafish can prove to be a valuable model to study AngII-RAS pathway-mediated pathophysiology. ABSTRACT: Hypertension, a common chronic condition, may damage multiple organs, including the kidney, heart, and brain. Thus, it is essential to understand the pathology upon ectopic activation of the molecular pathways involved in mammalian hypertension to develop strategies to manage hypertension. Animal models play a crucial role in unraveling the disease pathophysiology by allowing incisive experimental procedures impossible in humans. Zebrafish, a small freshwater fish, have emerged as an important model system to study human diseases. The primary effector, Angiotensin II of the RAS pathway, regulates hemodynamic pressure overload mediated cardiovascular pathogenesis in mammals. There are various established mammalian models available to study pathophysiology in Angiotensin II-induced hypertension. Here, we have developed a zebrafish model to study pathogenesis by Angiotensin II. We find that intradermal Angiotensin II injection every 12 h can induce cardiac remodeling in seven days. We show that Angiotensin II injection in adult zebrafish causes cardiomyocyte hypertrophy and enhances cardiac cell proliferation. In addition, Angiotensin II induces ECM protein-coding gene expression and fibrosis in the cardiac ventricles. Thus, this study can conclude that Angiotensin II injection in zebrafish has similar implications as mammals, and zebrafish can be a model to study pathophysiology associated with AngII-RAS signaling.