Mineralocorticoid and Estrogen Receptors in Endothelial Cells Coordinately Regulate Microvascular Function in Obese Female Mice

Obesity impairs endothelial-mediated vasodilation, the earliest step in vascular disease and a contributor to hypertension. We previously demonstrated that endothelial cell MR (mineralocorticoid receptor) deletion prevents obesity-induced microvascular dysfunction in females by increasing nitric oxide (NO)-mediated vasodilation. ERα (Estrogen receptor α) can oppose MR function, therefore, we hypothesized that ERα mediates the benefits of endothelial MR deficiency. Females lacking endothelial MR or wild-type littermates were fed control or high-fat diet for 20 weeks to cause obesity. MR deletion improved mesenteric artery endothelial-dependent vasodilation in obese females, and ex vivo ERα inhibition negated this protective effect. Endothelial MR deletion resulted in significantly more ERα mRNA and protein. In vitro, estrogen increased endothelial NO synthase phosphorylation, and this was inhibited by aldosterone and dependent on MR. Both proteins coimmunoprecipitated with striatin and a mimetic peptide that disrupts ERα-striatin binding also decreased MR-striatin interaction. Finally, removing endothelial MR in obese females restored endothelial function by increasing the NO component of vasodilation. Combined deletion of endothelial ERα negated the benefit of endothelial MR deletion. These results indicate that endothelial ERα prevents the detrimental effects of MR in obesity by increasing NO to rescue vasodilation in females. MR and ERα may compete for striatin binding within endothelial cells to regulate NO. These data identify a novel mechanism that promotes MR antagonism to prevent obesity-induced microvascular dysfunction in females.