Cardiac response to chronic restraint stress involves mineralocorticoid receptors in male Sprague-Dawley rats

In the present study, we aimed at elucidating whether exposure to chronic stress affects the expression of cardiac mineralocorticoid receptors (MRs), whether it influences cardiac structure and function, and whether MRs blockade attenuates the stress-induced changes. Young adult male Sprague-Dawley rats were divided into four groups: rats exposed to restraint stress, rats assigned to eplerenone treatment, rats exposed to restraint stress and eplerenone treatment, and a control group. After 4 weeks of the experiment, rats' blood pressure and heart rate were recorded, transthoracic echocardiography was performed, and blood samples and hearts were collected for further analysis. The study showed that chronic stress increases cardiac glucocorticoid mRNA expression but does not change the expression of MR mRNA. Chronic stress increases matrix metalloproteinases activity in the cardiac muscle. Mild left ventricular pro-hypertrophic changes were noted on echocardiogram. The changes were partially prevented by MR blockade with the use of eplerenone. These findings indicate that MRs participate in cardiac responses to chronic stress; however, this is not directly associated with significant changes in cardiac MRs expression.