Protective effect of naringin against radiation‐induced heart disease in rats via Sirt1/NF‐κB signaling pathway and endoplasmic reticulum stress

Abstract

This study was designed to explore the protective effect and mechanism of naringin (NG) on radiation‐induced heart disease (RIHD) in rats. Rats were divided into four x‐ray (XR) irradiation groups with different absorbed doses (0/10/15/20 Gy), or into three groups (control, XR, and XR + NG groups). Subsequently, the ultrasonic diagnostic apparatus was adopted to assess and compare the left ventricular ejection fraction (LVEF), left ventricular fractional shortening (LVFS), left ventricular internal diameter at end diastole (LVIDd), and left ventricular internal diameter at end systole (LVIDs) in rats. Hematoxylin–eosin (H&E) staining and Masson staining were applied to detect the pathological damage and fibrosis of heart tissue. Western blot was used to measure the expression levels of myocardial fibrosis‐related proteins, endoplasmic reticulum stress‐related proteins, and Sirt1 (silent information regulator 1)/NF‐κB (nuclear factor kappa‐B) signaling pathway‐related proteins in cardiac tissues. Additionally, enzyme‐linked immunosorbent assay was utilized to detect the activities of pro‐inflammatory cytokines, malondialdehyde (MDA), superoxide dismutase (SOD), and catalase (CAT) in cardiac tissue. The results showed that NG treatment significantly attenuated the 20 Gy XR‐induced decline of LVEF and LVFS and the elevation of LVIDs. Cardiac tissue damage and fibrosis caused by 20 Gy XR were significant improved after NG treatment. Meanwhile, in rats irradiated by XR, marked downregulation was identified in the expressions of fibrosis‐related proteins (Col I, collagen type I; α‐SMA, α‐smooth muscle actin; and TGF‐β1, transforming growth factor‐beta 1) and endoplasmic reticulum stress‐related proteins (GRP78, glucose regulatory protein 78; CHOP, C/EBP homologous protein; ATF6, activating transcription factor 6; and caspase 12) after NG treatment. Moreover, NG treatment also inhibited the production of pro‐inflammatory cytokines [interleukin‐6, interleukin‐1β, and monocyte chemoattractant protein‐1 (MCP‐1)], reduced the expression of MDA, and promoted the activities of SOD and CAT. Also, NG treatment promoted Sirt1 expression and inhibited p65 phosphorylation. Collectively, XR irradiation induced cardiac injury in rats in a dose‐dependent manner. NG could improve the cardiac injury induced by XR irradiation by inhibiting endoplasmic reticulum stress and activating Sirt1/NF‐κB signaling pathway.