Oleuropein suppresses oxidative, inflammatory, and apoptotic responses following glycerol-induced acute kidney injury in rats

Abstract

Aim: Here, we evaluated the possible protective effects of oleuropein, the major phenolic constituent in virgin olive oil against glycerol-induced acute kidney injury (AKI) in rats.

Main methods: Twenty-eight Sprague Dawley rats were allocated equally into four groups as follows: control group, oleuropein group (50 mg/kg body weight), AKI group and the oleuropein + AKI group. AKI was induced by injecting 50% glycerol (10 ml/kg body weight) intramuscularly.

Key findings: Glycerol injection increased the kidney relative weight as well as rhabdomyolysis (RM)- and AKI-related index levels, including the levels of creatine kinase, lactate dehydrogenase, creatinine, urea, and Kim-1 expression. Additionally, alteration in oxidative conditions in renal tissue was recorded, as confirmed by the elevated malondialdehyde and nitric oxide levels and the decreased glutathione content. Concomitantly, the protein and mRNA expression levels of antioxidant enzymes were suppressed. Moreover, Nfe2l2 and Hmox1 mRNA expression was also downregulated. Glycerol triggered inflammatory reactions in renal tissue, as evidenced by the increased pro-inflammatory cytokines and Ccl2 protein and mRNA expression, whereas myeloperoxidase activity was increased. Furthermore, glycerol injection enhanced apoptotic events in renal tissue by increasing the expression of the pro-apoptotic proteins and decreasing that of anti-apoptotic. However, oleuropein administration reversed the molecular, biochemical, and histological alterations resulting from glycerol injection.

Significance: Our data suggest that oleuropein has potential as an alternative therapy to prevent or minimize RM incidence and subsequent development of AKI, possibly due to its potent anti-stress, anti-inflammatory, and anti-apoptotic effects.

Keywords: Acute kidney injury; Apoptosis; Inflammation; Oleuropein; Oxidative stress; Rhabdomyolysis.