Effect of Thymoquinone on Oxidative Stress in Escherichia coli-Induced Pyelonephritis in Rats.

BACKGROUND: Recurrent urinary tract infections are important in children and adults with diabetes mellitus and/or incontinence due to risk of pyelonephritis (PYN) and renal damage. There is a positive correlation released free radicals during PYN and renal damage. Experimental studies showed that antioxidant agents improve renal damage when used immediately after bacterial inoculation. OBJECTIVE: The aim of the present study was to evaluate whether treatment by thymoquinone (TQ) before or during Escherichia coli inoculation prevents oxidative damage in acute pyelonephritis (PYN) in an ascending obstructive rat model. METHODS: In this study, 42 Wistar rats were grouped as follows: control, PYN (24, 48, and 72 hours), and TQ-PYN (24, 48, and 72 hours). E. coli (1 ×10(9) colony forming units) was inoculated into the bladder via urethral catheterization in both the PYN and TQ groups. TQ injections were performed 24 hours before bacteria inoculation and repeated at 24-hour intervals during the indicated time at a dose of 10 mg/kg body weight intraperitoneally in TQ groups. RESULTS: Superoxide dismutase activity was statistically lower in the TQ-PYN-48 and -72 groups than the PYN-48 and -72 groups (P < 0.001, P = 0.004, respectively). Catalase activity was significantly higher in PYN-24, -48, and -72 groups than the control group (P < 0.001). In addition, there was a significant difference between the TQ-PYN-24, -48, and -72 groups and PYN groups in terms of glutathione peroxidase activity (P < 0.001, P = 0.026, P = 0.046, respectively). When the TQ-PYN-72 group was compared with the PYN-72 group, malondialdehyde levels were significantly lower in the TQ-PYN-72 group than in the PYN-72 group (P = 0.033). A histologic examination also confirmed the protective effect of TQ. In statistical analysis of histopathologic findings, there were significant differences between the PYN-24 and TQ-PYN-24, PYN-48 and TQ-PYN-48, and PYN-72 and TQ-PYN-72 groups (P = 0.008, P < 0.001, P < 0.001, respectively). CONCLUSIONS: The results indicate that TQ administration attenuated the oxidative damage that occurred in PYN and, therefore, could be used as a supportive agent to protect the kidneys from oxidative damage caused by PYN.