P610Akt-mediated cardioprotective effects of aldosterone in type 2 diabetic mice

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Abstract

Purpose: Studies have shown that aldosterone would have angiogenic effects, and therefore would be beneficial in the context of cardiovascular diseases. We thus investigated the potential involvement of aldosterone in triggering a cardiac angiogenic response in the context of type-2 diabetes, and the molecular pathways involved.

Procedure: 3 week-old male mice, overexpressing aldosterone-synthase (AS), and their controls littermates (WT) were fed with a standard or high fat, high sucrose (HFHS) diet. After 6 months of diet, mice were sacrificed and cardiac samples were assayed by RT-PCR, immuno-blotting and -histology.

Findings: HFHS-diet induced type-2 diabetes (D) in WT and AS mice. VEGFa mRNAs were decreased in WT-D (-43%, P<0.05 vs. WT) while increased in AS-D mice (+236%, P<0.01 vs. WT-D). In WT-D hearts, the proapoptotic p38-MAPK was activated (P<0.05 vs. WT and AS-D) whereas Akt activity decreased. The AS-mice, that exhibited a cardiac upregulation of IGF1-R, showed an increase in Akt phosphorylation when diabetic (P<0.05 vs. WT and AS-D). Contrary to WT-D, AS-D hearts did not express inflammatory markers and exhibited a normal capillary density (P<0.05 vs. WT-D)

Conclusions: To our knowledge, this is the first study providing new insights into the mechanisms whereby aldosterone prevents diabetes-induced cardiac disorders.

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