Abstract
Although there is accumulating evidence which suggests that the administration of ghrelin could be used to preserve cardiac function, delay the progression of heart failure post-myocardial infarction, and attenuate ventricular remodeling, there is still no definitive data that clearly highlights the mechanisms by which ghrelin exerts cardioprotective effects. The present study aimed to investigate whether ghrelin could affect nuclear factor erythroid 2-related factor-2 (Nrf2), heme oxygenase-1 (HO-1), and endothelial nitric oxide synthase (eNOS) expression and exert anti-inflammatory as well as antioxidant-like actions through this signaling pathway. Rats were assorted into four groups with 10 in each: Group I (Control), Group II (received ghrelin only), Group III (MI was induced by isoproterenol (ISO)), Group IV (MI was induced by isoproterenol and within 30 min of each ISO dose, rats received ghrelin; 100 μg /kg subcutaneously two times per day). We assessed the effects of acylated ghrelin on the biochemical changes, ECG parameters, heart rate, histopathological scoring and the mRNA expression of eNOS, Nrf2 (confirmed immunohistochemically) as well as HO-1 genes in the cardiac tissues. Nuclear factor-κB, tumor necrosis factor-α, interleukin-6, and inducible nitric oxide synthase were assessed as inflammatory markers. Ghrelin markedly improved the oxidative stress injury and inflammation, showed histological preservation of the cardiac muscle fibers morphology, ameliorated the ISO-induced ECG changes and caused a significant elevation in eNOS, HO-1, and Nrf2 expression. In conclusion, ghrelin exerts cardioprotective effect in ISO-induced myocardial infarction by promoting the eNOS/Nrf2/HO-1 pathway.