Elabela Attenuates Doxorubicin-Induced Oxidative DNA Damage and Apoptosis in Rat Left Ventricular Myocardium

Background: Doxorubicin, a widely used chemotherapeutic agent, has been shown to increase reactive oxygen species (ROS) levels, disrupting cellular homeostasis not only in cancer cells but also in healthy tissues, particularly in cardiomyocytes, which leads to chemotherapy-induced cardiotoxicity. Therefore, new strategies are continually being explored to mitigate these adverse effects. One such approach is the use of additional substances with cardioprotective properties during doxorubicin therapy. A promising candidate is elabela, a peptide of the apelinergic system, which may exert protective effects against doxorubicin-induced oxidative stress in cardiomyocytes. Objectives: This study aims to evaluate the modulatory effects of elabela on oxidative stress markers, malondialdehyde (MDA) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) in the left ventricle of the myocardium following chronic doxorubicin administration in rats. Material and Methods: 32 male, 12-week-old Sprague-Dawley rats (SPRD) were randomly assigned to four experimental groups. For 28 days, all animals received continuous infusions (2.5 μL/h) via subcutaneously implanted osmotic pumps of 0.9% NaCl or elabela (40 μg/kg body weight/day or 200 μg/kg body weight/day). Simultaneously, animals were injected intraperitoneally 4 times at weekly intervals with 0.9% NaCl or DOX (3.5 mg/kg body weight). Next, the animals were sacrificed, and left ventricular (LV) cardiac tissue was collected for further analysis. MDA and 8-OHdG and elabela level in LV lysate were assessed by ELISA. The Ela expression in LV was quantified by Real-Time PCR. The TUNEL assay, labeled with a 5'-triphosphate strand, was used to assess the degree of apoptosis. Results: DOX treatment decreased both the Ela expression and elabela levels in the LV. Elabela administration at a dose of 200 µg/kg body weight/day significantly decreased ELA levels and Ela expression compared to the control group. The level of 8-OhdG was unexpectedly decreased in the DOX group compared to controls, while elabela treatment at both doses restored 8-OHdG levels observed in the control group. However, TUNEL staining demonstrated that elabela administration at 200 µg/kg body weight/day reduced the number of apoptotic cardiomyocytes compared to the DOX-only group, indicating a protective effect against DOX-induced apoptosis. The lower dose of 40 µg/kg body weight/day showed a moderate, non-significant attenuation of apoptosis. Conclusions: Elabela showed a protective effect against DOX-induced cardiomyocyte apoptosis in the LV by promoting processes that reduce oxidative stress in cardiac cells.