Cortistatin Improves Cardiac Function After Acute Myocardial Infarction in Rats by Suppressing Myocardial Apoptosis and Endoplasmic Reticulum Stress

Abstract

Objectives: The endoplasmic reticulum (ER) stress-induced apoptotic pathway is associated with the development of acute myocardial infarction (AMI). Cortistatin (CST) is a novel bioactive peptide that inhibits apoptosis-related injury. Therefore, we investigated the cardioprotective effects and potential mechanisms of CST in a rat model of AMI. Methods: Male Wistar rats were randomly divided into sham, AMI, and AMI + CST groups. Cardiac function and the degree of infarction were evaluated by echocardiography, cardiac troponin I activity, and 2,3,5-triphenyl-2H-tetrazolium chloride staining after 7 days. The expression of CST, ER stress markers, and apoptotic markers was examined using immunohistochemistry and Western blotting. Results: Compared to the AMI group, the AMI + CST group exhibited markedly better cardiac function and a lower degree of infarction. Electron microscopy and terminal deoxynucleotidyl transferase dUTP nick end labeling confirmed that myocardial apoptosis occurred after AMI. Cortistatin treatment reduced the expression of caspase 3, cleaved caspase 3, and Bax (proapoptotic proteins) and promoted the expression of Bcl-2 (antiapoptotic protein). In addition, the reduced expression of glucose-regulated protein 94 (GRP94), glucose-regulated protein 78 (GRP78), CCAAT/enhancer-binding proteins homologous protein, and caspase 12 indicated that ER stress and the apoptotic pathway associated with ER stress were suppressed. Conclusions: Exogenous CST has a notable cardioprotective effect after AMI in a rat model in that it improves cardiac function by suppressing ER stress and myocardial apoptosis.