Morphofunctional characteristics of remodeling processes in the structural components of the rat spleen during prolonged exposure to a mixture of food additives

Abstract

The aim of the study was to determine the morpho­functional charac­teristics of spleen remodeling in rats during prolonged oral administration of a mixture of food additives at subtoxic doses. The study included 70 Wistar rats, with equal numbers of males and females, divided into seven groups of 10 animals each: one week-0 group and six experimental groups. The animals received monosodium glutamate at a dose of 20 mg/kg, Ponceau 4R at a dose of 5 mg/kg, and sodium nitrite at a dose of 0.6 mg/kg and were euthanized after 1, 4, 8, 12, 16, or 20 weeks by sodium thiopental overdose under ether anesthesia. Superoxide dismutase and catalase activities and malondialdehyde and nitrite concentrations were measured spectrophotometrically in a 10% spleen homogenate; Ki-67-positive and CD20-positive cells were evaluated immunohistochemically. Data were presented as mean±standard deviation and analyzed using the Shapiro-Wilk test, Welch analysis of variance, the Kruskal-Wallis test, Holm-adjusted pairwise comparisons, quadratic regression, and Spearman rank correlation. At week 12, superoxide dismutase and catalase activities were 58.5% and 57.8% lower than in the week-0 group, respectively, whereas malondialdehyde concentration increased 7.23-fold. Nitrite concentration peaked at week 8 and was 83.3% above the level in the week-0 group. The number of Ki-67-positive cells was lowest at week 16, (by 90.7% below that in the week-0 group); the number of CD20-positive cells increased by 56.6% at week 8 and decreased by 28.1% at week 20, with Holm-adjusted p<0.05 for all reported comparisons. Thus, prolonged exposure to the mixture of food additives was accompanied by oxidative-nitrosative stress and exposure duration-dependent changes in proliferative activity and the B-cell component of the spleen.