Cisplatin-based chemotherapy is responsible for a large number of renal failures, and it is still associated with high rates of mortality today. Oleuropein (OLE) presents a plethora of pharmacological beneficial properties. In this study we investigated whether OLE could provide sufficient protection against cisplatin-induced nephrotoxicity. With this aim, Sprague-Dawley rats were divided into eight groups: control; 7 mg/kg/d cisplatin, 50 mg/kg, 100 mg/kg, and 200 mg/kg OLE; and treatment with OLE for 3 days starting at 24 hours following cisplatin injection. After exposure to the chemotherapy agent and OLE, oxidative DNA damage was quantitated in the renal tissue of experimental animals by measuring the amount of 8-hydroxy-2'-deoxyguanosine (8-OHdG) adducts. Malondialdehyde (MDA) level, total oxidative stress (TOS), and total antioxidant status (TAS) were assessed to determine the oxidative injury in kidney cells. The histology of the kidney was examined using four different staining methods: hematoxylin-eosin (H&E), periodic acid Schiff (PAS), Masson trichrome, and amyloid. In addition, the blood urea nitrogen (BUN), uric acid (UA), and creatinine (CRE) levels were established. Our experimental data showed that tissue 8-OHdG levels were significantly higher in the cisplatin group when compared to the control group. The glomerular cells were sensitive to cisplatin as tubular cells. In addition, treatment with cisplatin elevated the levels of BUN, UA, CRE, and TOS, but lowered the level of TAS compared to the control group. The OLE therapy modulated oxidative stress in order to restore normal kidney function and reduced the formation of 8-OHdG induced by cisplatin. Furthermore, the OLE treatment significantly reduced pathological findings in renal tissue. We demonstrate for the first time that OLE presents significant cytoprotective properties against cisplatin-induced genotoxicity by restoring the antioxidant system of the renal tissue. According to our findings, OLE is a promising novel natural source for the prevention of serious kidney damage in current chemotherapies.

Background.Inflammation and oxidative stress (OxS) contribute to the pathogenesis of diabetic kidney disease (DKD) and contrast-induced nephropathy (CIN). Patients with DKD were found to be more prone to CIN. Interleukin-33 (IL-33) is a proinflammatory cytokine, but its role in DKD and CIN is unknown.Methods.Thirty male Sprague-Dawley rats were enrolled. The first group was comprised of healthy rats (HRs), whereas the other four groups were made up of diabetic rats (DRs), diabetic rats with contrast-induced nephropathy (CIN + DRs), melatonin-treated diabetic rats (MTDRs), and melatonin-treated CIN + DRs (MTCIN + DRs). All groups except the HRs received 50 mg/kg/day streptozotocin (STZ). CIN + DRs were constituted by administrating 1.5 mg/kg of intravenous radiocontrast dye on the 35th day. MTDRs and MTCIN + DRs were given 20 mg/kg/day of intraperitoneal injection of melatonin (MT) from the 28th day for the constitutive seven days.Results.We observed increased IL-33 in the kidney tissue following induction of CIN in DRs. To determine whether MT is effective in preventing CIN, we administered MT in CIN + DRs and demonstrated that kidney tissue levels of OxS markers, inflammatory cytokines, and IL-33 were significantly diminished in MTCIN + DRs compared with other groups without MT treatment (p<0.05).Conclusion.Inhibition of IL-33 with MT provides therapeutic potential in DKD with CIN.