Renoprotective effects of vitamin D and thymoquinone, alone and in combination, in a rat co-treatment model of gentamicin-induced acute kidney injury.

To investigate the prophylactic (co-treatment) effects of vitamin D (VD), thymoquinone (TQ), and their combination against gentamicin (GM)-induced acute kidney injury (AKI). Forty male Wistar rats were divided into five groups: negative control, GM-treated positive control (PC; 100 mg/kg/day), and three groups receiving GM simultaneously with VD (210 IU/kg/day), TQ (12.5 mg/kg/day), or both. The GM-treated rats developed classical AKI symptoms, including elevated serum creatinine and urea, altered urine parameters, abnormal renal histology, and increased renal cell apoptosis. Moreover, renal tissues from PC rats showed a marked increase of oxidative stress markers (MDA/H2O2/protein carbonyls) and pro-inflammatory cytokines (TNF-α/IL-1β/IL-6/IL-18/TLR2), with inhibition of antioxidants (GSH/GPx1/SOD/CAT) and interleukin-10. The expression of pathogenic mediators (NFκB-p50/iNOS/TGF-β1) was significantly upregulated, while renoprotective molecules (Nrf2/AMPK-α/AKT1/survivin) were inhibited. Both VD and TQ provided partial renal protection, with TQ showing relatively greater efficacy under the tested conditions. However, their co-administration demonstrated superior efficacy relative to both monotherapies, reflected by better restoration of renal function and histology alongside stronger reductions in oxidative stress and inflammation. This combination also resulted in a more effective downregulation of pathogenic molecules alongside enhanced expression of the renoprotective pathways. This is the first study to report a relative advantage of TQ over VD under the tested conditions and demonstrate that VD and TQ co-therapy exerted enhanced renoprotection in GM-induced AKI. These ameliorations were potentially mediated through enhanced modulation of renal oxidative stress and inflammation. However, further studies should explore VD and TQ co-therapy effects on additional pathogenic mechanisms underlying aminoglycoside-induced nephropathy.