Effects of Different Doses of Royal Jelly on Oxidative Stress Parameters in Streptozotocin-Induced Diabetic Rats

Chronic hyperglycemia in diabetes increases the cellular oxidant burden while weakening antioxidant defense capacity. Royal jelly has been suggested to exert antioxidant effects; however, its tissue-specific activity at different doses remains unclear. The present study investigated malondialdehyde (MDA) concentrations and superoxide dismutase (SOD) activities in serum, brain, kidney, heart, and testis samples obtained from male rats with streptozotocin (STZ)-induced diabetes after royal jelly treatment. Thirty-six adult male Sprague–Dawley rats were allocated to healthy control, diabetic control, healthy royal jelly (300 mg/kg), and diabetic royal jelly groups receiving 50, 150, or 300 mg/kg. A 50 mg/kg dose of STZ was administered intraperitoneally to establish diabetes, and royal jelly was given orally once daily for four weeks. Biochemical measurements were performed spectrophotometrically. Serum MDA concentrations were comparable among groups, whereas serum SOD activity showed a significant group effect (p = 0.005), with lower activity in diabetic controls than in the healthy control and healthy royal jelly groups. Renal MDA was elevated and renal SOD activity was reduced in diabetic controls relative to the healthy groups (p < 0.001 and p = 0.007, respectively). Cardiac MDA remained unchanged, while cardiac SOD activity was lower in diabetic controls than in healthy controls (p = 0.008). No significant group differences were detected in brain or testicular parameters (p > 0.05). Royal jelly did not significantly reduce renal MDA; nevertheless, SOD activities in serum, kidney, and heart tended to be higher in treated diabetic groups than in diabetic controls and were comparable to healthy control values. These results indicate that royal jelly did not clearly suppress lipid peroxidation but may modestly limit the diabetes-related decline in antioxidant defense.