Turkish Propolis Mitigates Oxidative Stress and Endoplasmic Reticulum Stress in Cardiac Damage Caused by Doxorubicin in Rats

Purpose: This study examined the effects of propolis extracted with ethanol (EPE) or olive oil (OPE) on the endoplasmic reticulum (ER) and oxidative stress in doxorubicin (DXR)-induced cardiac damage in rats. Materials and Methods: Six groups of Sprague‒Dawley rats were used in this research: Control, EPE, OPE, DXR, EPE+DXR, and OPE+DXR. The extracts were administered orally for two weeks (50 mg/kg/day), and DXR was injected 48 hours before sacrifice (15 mg/kg). Cardiac malondialdehyde (MDA) and glutathione (GSH) levels and catalase (CAT) activity were assayed spectrophotometrically, while cardiac glucose-regulated protein (GRP)-78, pro-caspase 12, and serum troponin I levels were determined via ELISA. Results: The DXR group presented elevated serum troponin I, indicating cardiac injury, increased MDA, decreased CAT activity, and reduced GSH, indicating oxidative stress, along with elevated GRP78 and decreased pro-caspase 12, indicating ER stress. Pretreatment with EPE or OPE significantly prevented DXR-induced increases in troponin I and MDA, as well as decreases in GSH, CAT activity, and pro-caspase 12, but did not significantly alter cardiac GRP78 levels. Compared with the EPE+DXR group, the OPE+DXR group presented higher levels of CAT activity (p