The aim of this study is to investigate the protective effects of thymoquinone (TQ) and ebselen (Eb) on arsenic (As)-induced renal toxicity in female rats. Sodium arsenite was orally administrated at a dose of 20 mg/kg body weight daily for 28 days, either alone or 1 h before TQ (10 mg/kg) or Eb (5 mg/kg) administration. Renal tissue As concentration and oxidative stress markers, including lipid peroxidation (LPO), nitrite/nitrate, and glutathione (GSH) levels, were determined. In addition to the oxidative stress response, antioxidant enzyme activities including that of superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase were measured. Exposure to As elicited a significant increase in As concentration and significant modifications to the redox state of the kidney, as was evidenced by a significant elevation in LPO and nitrite/nitrate concentration, with a concomitant reduction in GSH content and antioxidant enzyme activity. The oxidant/antioxidant imbalance observed in As toxicity was associated with a significant elevation in renal tumor necrosis factor α, interleukin 6, B-cell lymphoma 2 (Bcl-2)-associated X protein, and caspase 3 levels, in addition to a significant decrease in Bcl-2 levels. Post-administration of TQ and Eb markedly prevented As-induced oxidative stress, inflammation, apoptosis, and As accumulation in the renal tissue and reduced histological renal damage. These findings demonstrate that TQ, the main bioactive phytochemical constituent of Nigella sativa seed oil, and Eb, an organoselenium compound, could significantly inhibit As-induced oxidative damage, apoptosis, and inflammation, and significantly attenuate the accumulation of As in renal tissues by facilitating As biomethylation and excretion.
Keywords: Arsenite; ebselen; inflammation; kidney; oxidative stress; thymoquinone.