Evaluation of Oxidative Stress Biomarkers in the Renal Tissue of Rats and Serum Biochemical Parameters After the Administration of Nitrate in Drinking Water and Vitamin C: an Experimental Study

Abstract

Background: Nitrate (NO3-) is one of the inorganic anions produced from the oxidation of nitrogen. The organic or inorganic nitrogen may act as a carcinogen depending on the reduction of nitrate to nitrite and the subsequent reactions of nitrite with other molecules, leading to the formation of N-nitroso compounds. Objectives: This study aimed to determine the effects of nitrate and Vitamin C on oxidative stress in the renal tissue of rats. Methods: This experimental study was conducted in Iran during the 2017 - 2018. The sample size was estimated to include 55 Wistar male rats using Morgan's table and Cochran's formula. In total, 49 rats were selected and divided into seven groups of: (1) NO3 = 0 mg/L (control), (2) NO3 = 10 mg/L, (3) NO3 = 45 mg/L, (4) NO3 = 200 mg/L, (5) NO3 = 10 mg/L + Vitamin C 20 mg/100 g BW (Body Weight), (6) NO3 = 45 mg/L + Vitamin C 20 mg/100 g BW, and (7) NO3 = 200 mg/L + Vitamin C 20 mg/100 g BW. Blood samples were obtained to determine blood urea nitrogen (BUN) and creatinine. An autopsy was performed on the renal tissue to evaluate oxidative stress indicators including malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH). Results: In this research, the fourth group showed a significant increase in the level of creatinine (50.14 ± 2.6, 43.14 ± 1.21, P = 0.01) and BUN (0.72 ± 0.04, 0.57 ± 0.11, P = 0.003) compared to the control group. On the other hand, a significant increase was observed in the level of MDA in the fourth group compared to the control group (P = 0.01), whereas a significant reduction was found in the levels of CAT (P = 0.001), SOD (P = 0.02), and GSH (P = 0.02). In addition, the levels of creatinine and BUN significantly reduced in the seventh group compared to the fourth group (P < 0.05). Furthermore, the use of Vitamin C resulted in a significant reduction in MDA and an increase in SOD, CAT, and GSH in the seventh group compared to the fourth group (P < 0.05). Conclusions: According to the results of the study, nitrate in drinking water and the prescription of Vitamin C had no significant effect in the presence of nitrate doses of 10 and 45 mg/L. However, a 200 mg/L dose of nitrate significantly affected BUN, serum creatinine, and oxidative stress indicators, causing the kidney disease.