Aldosterone Induces Vascular Insulin Resistance by Increasing Insulin-Like Growth Factor-1 Receptor and Hybrid Receptor

Abstract

Objective-We previously showed that aldosterone induces insulin resistance in rat vascular smooth muscle cells (VSMCs).Because insulin-like growth factor-1 receptor (IGF1R) affects insulin signaling, we hypothesized that aldosterone induces vascular insulin resistance and remodeling via upregulation of IGF1R and its hybrid insulin/insulin-like growth factor-1 receptor. Methods and Results-Hybrid receptor expression was measured by immunoprecipitation. Hypertrophy of VSMCs was evaluated by 3 H-labeled leucine incorporation. Aldosterone (10 nmol/L) significantly increased protein and mRNA expression of IGF1R and hybrid receptor in VSMCs but did not affect insulin receptor expression. Mineralocorticoid receptor blockade with eplerenone inhibited aldosterone-induced increases in IGF1R and hybrid receptor. Aldosterone augmented insulin (100 nmol/L)-induced extracellular signal-regulated kinase 1/2 phosphorylation. Insulin-induced leucine incorporation and ␣-smooth muscle actin expression were also augmented by aldosterone in VSMCs. These aldosterone-induced changes were significantly attenuated by eplerenone or picropodophyllin, an IGF1R inhibitor. Chronic infusion of aldosterone (0.75 g/hour) increased blood pressure and aggravated glucose metabolism in rats. Expression of hybrid receptor, azan-positive area, and oxidative stress in aorta was increased in aldosterone-infused rats. Spironolactone and tempol prevented these aldosterone-induced changes. Key Words: insulin resistance Ⅲ reactive oxygen species Ⅲ receptors Ⅲ signal transduction Ⅲ aldosterone I nsulin resistance is a major attribute of type 2 diabetes mellitus and metabolic syndrome. 1 Cardiovascular complications are often seen in these patients, and vascular insulin resistance is considered to be involved in proatherogenic changes and subsequent cardiovascular events. 2 There is growing interest in the role of aldosterone and its receptor, mineralocorticoid receptor (MR), in the pathogenesis of insulin resistance. 3 For instance, clinical studies have shown that patients with primary aldosteronism exhibit impaired glucose tolerance. 4 Some possible mechanisms of insulin resistance induced by aldosterone have been considered, such as a low serum potassium concentration, and direct effects of aldosterone on insulin signaling. 5,6 Previously, we have demonstrated that aldosterone induces insulin resistance in rat vascular smooth muscle cells (VSMCs) via the downregulation of insulin receptor substrate-1, a key molecule of insulin signaling pathway. 7 Our data also clearly showed that aldosterone attenuates glucose metabolism in VSMCs. However, the precise molecular mechanisms responsible for aldosterone-induced VSMC insulin resistance and proatherogenic changes have not been identified. Conclusion-AldosteroneInsulin induces various actions, such as glucose metabolism and normal cell physiology, by binding to the insulin receptor (IR). 8 The VSMCs express not only IR but also insulin-like growth factor-1 receptor (IGF1R). 8 Compared with IR, IGF1R is more ab...

Increased prevalence of diabetes mellitus and the metabolic syndrome in patients with primary aldosteronism of the German Conn's Registry

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Preconditioning actions of aldosterone through p38 signaling modulation in isolated rat hearts

“…There is increasing evidence of unfavorable effects of aldosterone on the cardiovascular system, in experimental models as well as large clinical trials (Pitt et al 2003), primarily via mineralocorticoid receptor (MR)-dependent actions (Caprio et al 2008, Matsui et al 2008, Rickard et al 2012, Sherajee et al 2012, Diaz et al 2014, Nolly et al 2014). …”

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