RESUMO
ObjectiveTo explore how hyperthyroidism induces ventricular remodeling via activating β-catenin/FoxO1 in rat cardiomyocytes. MethodsHyperthyroidism-induced ventricular remodeling rat models were established by intraperitoneal injection of levothyroxine （T4） at 0.1 mg/kg for 30 days. β-catenin inhibitor MSAB （14 mg/kg） was administrated for 30 days. We used western blot to detect the expression of myocardial hypertrophy marker ANP， β-catenin and FoxO1； immunofluorescence to examine the expression and intracellular distribution of β-catenin and FoxO1. Hyperthyroidism-induced cardiomyocyte hypertrophy rat models were established by treatment of triiodothyronine （T3） into cultured primary neonatal rat cardiomyocytes for 24 hours. β-catenin siRNA （30 nmol/L） was used to down-regulate β-catenin expression in cardiomyocytes. Western blot and immunofluorescence were used to analyze the effects of β-catenin inhibition on the hyperthyroidism-induced cardiomyocyte hypertrophy. ResultsFollowing Wnt/β-catenin activation， β-catenin was found increased nuclear expression， to bind to the nuclear transcriptional factors and regulate the gene expression. β-catenin nuclear expression was significantly increased in the hyperthyroidism-induced ventricular remodeling rats， but no change was found in the expression of typical transcriptional factor TCF7l2. Our results revealed that inhibiting β-catenin by MSAB attenuated the hyperthyroidism-induced rat ventricular remodeling. Further analysis indicated that β-catenin/FoxO1 expression was significantly increased in hyperthyroidism-induced myocardial hypertrophy which could be attenuated by suppressing β-catenin/FoxO1 in cardiomyocytes. Conclusionsβ-catenin/FoxO1 is activated in hyperthyroidism-induced myocardial hypertrophy and β-catenin/FoxO1 inhibition attenuates hyperthyroidism-induced cardiomyocyte hypertrophy.