Abstract Body (Do not enter title and authors here): Background: Aldosterone regulates blood pressure and electrolyte balance. However, overactivation of the mineralocorticoid receptor (MR) and elevated aldosterone levels are implicated in the pathogenesis of cardiometabolic disorders, though the underlying mechanisms are not fully understood. In this study, we investigated whether a novel, non-steroidal selective MR blocker, esaxerenone, ameliorates the development of metabolic disorders in obese mice models and examined the underlying mechanism.
Methods: Esaxerenone (3 mg/kg/day) was orally administered to high-fat diet (HFD)-fed C57BL/6J or normal chow-fed db/db mice. Metabolic parameters, tissue morphology, and effects of esaxerenone on insulin sensitivity were assessed. Gene expression and insulin signaling, determined by Akt phosphorylation, were examined using quantitative RT-PCR and western blotting, respectively. In in-vitro experiments, insulin targets cell lines such as 3T3-L1 adipocytes, HepG2 cells, and C2C12 myotubes were used. Insulin-responsive cells were treated with 10 nM or 100 nM esaxerenone or eplerenone for 30 minutes before 4-hour 1000 nM aldosterone stimulation. Insulin signaling was assessed 15 minutes after stimulation with 17 nM insulin.
Results: Esaxerenone improved insulin sensitivity (P<0.05) without altering metabolic parameters in HFD-induced obese and db/db mice. Esaxerenone suppressed fat accumulation, adipocyte size, and liver lipid droplets compared with the vehicle-treated group (P<0.01). In adipose tissue, esaxerenone reduced macrophage infiltration (P<0.01) and the expression of inflammatory molecules (P<0.05). In in-vitro experiments, aldosterone significantly decreased the expression levels of PPARγ and adiponectin in 3T3-L1 adipocytes. Moreover, aldosterone attenuated insulin-induced Akt phosphorylation in 3T3-L1 adipocytes, HepG2 cells, and C2C12 myotubes in a dose-dependent manner (P<0.01). Pretreatment with esaxerenone reversed the effect of aldosterone, whereas eplerenone, an MR antagonist, did not show a similar effect at the same dose.
Conclusion: Inhibition of MR by esaxerenone improved insulin sensitivity in HFD-induced obese and genetically diabetic mice. The reduction of inflammation and fat accumulation and enhancement of insulin signaling were suggested to be underlying mechanisms. Esaxerenone might be a beneficial therapeutic approach for managing metabolic disorders.