Activation of the signaling pathway by hyperglycemia induces cardiac remodeling and dysfunction in adult zebrafish.

Hyperglycemia is an independent risk factor for diabetic cardiomyopathy in humans; however, the underlying mechanisms have not been thoroughly elucidated. Zebrafish () was used in this study as a novel vertebrate model to explore the signaling pathways of human adult cardiomyopathy. Hyperglycemia was induced by alternately immersing adult zebrafish in a glucose solution or water. The hyperglycemic fish gradually exhibited some hallmarks of cardiomyopathy such as myocardial hypertrophy and apoptosis, myofibril loss, fetal gene reactivation, and severe arrhythmia. Echocardiography of the glucose-treated fish demonstrated diastolic dysfunction at an early stage and systolic dysfunction at a later stage, consistent with what is observed in diabetic patients. Enlarged hearts with decreased myocardial density, accompanied by decompensated cardiac function, indicated that apoptosis was critical in the pathological process. Significant upregulation of the expression of and its downstream targets calreticulin () and was noted in the glucose-treated fish. High-glucose stimulation evoked marked apoptosis of primary cardiomyocytes, which was rescued by the p53 inhibitor pifithrin-μ. experiments were performed using compound treatment and genetically via cell infection. Genetically, knockout of induced decreased expression of , and Upregulation of resulted in increased expression, whereas the level of remained unchanged. An adult zebrafish model of hyperglycemia-induced cardiomyopathy was successfully established. Hyperglycemia-induced myocardial apoptosis was mediated, at least in part, by activation of the -- pathway , resulting in cardiac dysfunction and hyperglycemia-induced cardiomyopathy.