Abstract
It is well‐known that high levels of thyroid hormone promote cardiomyocyte hypertrophy, which in part is mediated by activation of Renin‐Angiotensin System (RAS). Recent study of our group demonstrated that the contralateral RAS axis (ACE2/Angiotensin‐(1–7)/Mas receptor) is also involved in this cardiac hypertrophy model and that transgenic rats overexpressing circulating levels of Angiotensin‐(1‐7) (Ang‐(1‐7)) present an improvement of cardiac function and attenuation of cardiac hypertrophy. However, the molecular mechanisms involved in these Ang‐(1‐7) actions have not been fully elucidated. The aim of this study was to investigate if the anti‐hypertrophic effect of Ang‐(1‐7) also occurs in isolated cardiomyocytes, as well as the involvement of the Foxo3 signaling pathway for these effects. All experiments were approved by the Ethics Committee on Animal Experimentation of ICB‐USP (n030/12/CEUA). Primary cardiomyocytes cultures obtained from neonatal rats were treated with triiodothyronine (T3) (15nM) and/or Angiotensin‐(1‐7) (Ang‐(1‐7)) (100nM). All data were analyzed by ANOVA followed by Tukey's post hoc test, and values of P<0.05 were considered statistically significant. The Ang‐(1‐7) treatment prevented the cardiomyocyte hypertrophy induced by T3, which was confirmed by reduction cell surface area, L‐[3,4,5‐3H] leucine incorporation and BNP gene expression. Combined treatment with the MAS receptor antagonist (A779, 100nM) impaired the anti‐hypertrophic effect of Ang‐(1‐7). Regarding molecular mechanisms, although Ang‐(1‐7) treatment did not impair the rapid activation of Akt promoted by T3, Ang‐(1‐7) treatment reduced the phosphorylation of Foxo3 (inactive form) and promoted the nuclear accumulation of Foxo3 in cardiomyocytes, indicating the activation of this protein. Collectively, these findings indicate an important cardioprotective effect of Ang‐(1‐7) in isolated cardiomycoytes treated with T3, occurring via MAS receptor and with possible participation of Foxo3.Support or Funding InformationFoundation for the Support of Research in the State of São Paulo (FAPESP) and National Council of Technological and Scientific Development (CNPq).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
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