Oxymetholone, a synthetic anabolic steroid, is widely used for medical and performance-enhancing purposes but is associated with significant toxicity. Zinc oxide nanoparticles (ZnO-NPs) have attracted attention for their antioxidant and anti-inflammatory properties, which may counteract such toxic effects. This study investigates the protective role of ZnO-NPs against oxymetholone-induced liver and kidney damage in rats. Twenty-four rats were randomly assigned to four groups and treated orally as follows: control, oxymetholone (10 mg/kg), ZnO-NPs (5 mg/kg), and oxymetholone + ZnO-NPs. Oxymetholone administration significantly increased serum levels of urea, creatinine, alanine aminotransferase (ALT), and aspartate aminotransferase (AST). Furthermore, oxidative stress markers, such as malondialdehyde (MDA), were significantly elevated, whereas reduced glutathione (GSH) levels were decreased in both hepatic and renal tissues. Oxymetholone exposure also upregulated the expression of pro-inflammatory and stress-related genes, including tumor necrosis factor-alpha (TNF-α), nuclear factor kappa B (NF-κB), signal transducer and activator of transcription 3 (STAT3), and nibrin (NBN). In contrast, it downregulated antioxidant genes such as nuclear factor erythroid 2-related factor 2 (Nrf2), catalase (CAT), and superoxide dismutase (SOD). Histopathological examination revealed extensive liver and kidney damage, with immunohistochemistry demonstrating marked NF-κB expression. However, concurrent administration of ZnO-NPs mitigated these toxic effects by restoring antioxidant balance, modulating inflammatory pathways, and preserving tissue integrity. These findings suggest that ZnO-NPs have a protective role against oxymetholone-induced oxidative stress, inflammation, and tissue damage in hepatic and renal tissues.
