Role of thioredoxin‐binding protein 2 in cardiac oxidative stress and energy metabolism of rats supplemented with vitamin D (1041.14)

Abstract

Vitamin D (VD) is important for cardiac development and functioning but, recent studies have shown that VD receptor is undetectable in cardiac muscle. On the other hand, in the heart is present a thioredoxin‐binding protein (TBP‐2) which is up regulated by VD. The aim of this study was to evaluate whether supplementation with different doses of VD results in changes in TBP‐2 protein expression, cardiac oxidative stress and energy metabolism. Methods: 48 male rats allocated into 4 groups: control (C, n=12) received standard chow; VD3 (n=12), VD5 (n=12) and VD10 (n=12) received 3000, 5000 and 10000 IU of cholecalciferol/kg chow for 2 months. Statistical analysis was performed by ANOVA or Kruskal‐Wallis test and Test for Linear Trend. Results: The TBP‐2 protein expression was higher in VD10 group compared to control and VD3 in a dose‐dependent manner (p<0.001). In relation to the oxidative stress, the thioredoxin (Trx) protein expression decreased in dose‐dependent manner (p=0.019) and lipid hydroperoxide (LH) was higher in VD10 compared to other groups. The increase in LH was dose dependent (p<0.001). In relation to cardiac energy metabolism, the peroxisome proliferator‐activated receptor‐γ coactivator‐1 α (PGC‐1α) protein expression was lower in VD10 compared to control in dose‐dependent manner (p=0.002). Activity of the enzymes: 3‐hydroxyacyl coenzyme‐A dehydrogenase and citrate synthase was lower and lactate dehydrogenase was higher in VD10 compared to other groups. Conclusion: The increased expression of TBP‐2 in rats with VD supplementation may be associated with increased oxidative stress and changed cardiac energy metabolism in these animals.Grant Funding Source: Supported by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)