Immunohistochemical Evaluation of the Effects of Nitrate in Drinking Water on Laminin Alpha-5 Expression in Rat Renal Glomeruli

Nitrate is a polyatomic ion with the molecular formula NO3-. Nitrate poisoning occurs through metabolism in the liver and conversion of nitrate to nitrite, which acts as an intermediary. Laminins are high-molecular weight proteins in extracellular matrix, regarded as one of the major components of the basement membrane. The current study aimed to evaluate the effects of nitrate on laminin α5 expression in rat renal glomeruli. The current interventional study was conducted on 24 male Wistar rats in Iran during 2014 - 2016. Samples were randomly divided into four groups as follows: 1) Normal drinking water, 2) Distilled water containing 45 mg/L of nitrate, 3) Distilled water containing 100 mg/L of nitrate and 4) Distilled water (control). Sample size consisted of 48 kidneys randomly collected from rats. Laminin α5 content in renal glomeruli was determined using the immunohistochemistry (IHC) protocol. Data analysis was performed using the Kruskal-Wallis test and the Spearman correlation coefficient; P value below 0.05 was considered statistically significant. In the study, intensity of reaction to anti-laminin was not the same in renal glomeruli. While there was no significant difference between the groups one and two (P > 0.05), a significant difference was observed between the groups three and four (P < 0.05) in this regard. According to the results of the study, standard amount of nitrate in drinking water had no significant impact on laminin content. On the other hand, exceeded nitrate concentrations limited the distribution of laminin, leading to potential adverse effects on glomerular basement membrane.