HISTOLOGICAL AND MORPHOLOGICAL CHANGES IN THE LYMPHOID STRUCTURES OF THE GASTRIC MUCOUS MEMBRANE IN WHITE RATS WITH THE ADMINISTRATION OF SODIUM GLUTAMATE
Authors: Kochmar Mykhailo Yu. , Holosh Yuliia V. , Bedey Nelli V. , Pushkash Ivan I. , Pushkash Lyubov Yu. 
Published: December 2023

The aim: To determine the histological and morphological changes of the lymphoid structures of the stomach in male rats under the influence of oral sodium glutamate at the rate of 15 mg/kg of body weight.
Materials and methods: The scientific experiment was performed on 20 white non-linear male rats of reproductive age (4-5 months). The experimental animals were divided into two groups (10 rats in each group), which were orally received monosodium glutamate at a dose of 15 mg/kg body weight every day. We studied the effect of 2 and 4 weekly administration of monosodium glutamate at a dose of 15 mg/kg body weight, respectively, in the I and II groups of experimental animals (depending on the week of their decapitation). Rats of the control groups (n=10) were injected with a placebo for 2 and 4 weeks, namely 0.5 ml of dechlorinated tap water at room temperature. Intact control animals were also divided into two groups, 5 rats each, depending on the week of decapitation: respectively, III group – decapitation on the 2nd week of the experiment; IV group - decapitation on the 4th week of the experiment. After the experiments were completed, animals were decapitated under light ether anesthesia. According to the purpose of the study, pieces of rat stomach measuring 1.0 x 1.0 cm were taken from the front wall of the bottom of the stomach near the great curvature, cardiac and portal parts of the organ. Histological preparations were examined using a MICROmed SEO SСAN light microscope and a Vision CCD Camera. Morphometric studies were carried out according to the method of S. B. Stefanov, using grids No. 3/16. For electron microscopic examination, pieces of the stomach wall of rats were fixed in a 2.5% solution of glutaraldehyde in a 0.1 M phosphate buffer (pH 7.2-7.4) with subsequent fixation in a 2.0% solution of osmium tetroxide. After dehydration in alcohols and acetone, the material was embedded in eponaraldite. Sections were made on an LKB-8800-III ultramicrotome and studied using a JEM - 100-V microscope. To study the structural components of the lymphoid formations of the mucous membrane of different parts of the stomach of rats, semi-thin sections were made for the purpose of sharpening the blocks, which were stained with methylene blue.
Results: The analysis of the obtained data of the conducted experiment indicates that the administration of monosodium glutamate in a dose of 15 mg/kg of body weight to rats already after 14 days leads to an increase in the density and size of the lymphoid structures of the GMM. The number of immunocompetent cells between the fundus of the gastric glands and the muscle plate increases in the diffuse lymphoid tissue of the gastrointestinal tract of rats in all its parts, both in the I and II groups of experimental animals. These changes are most pronounced in the cardiac and portal parts of the stomach. In both groups of experimental animals, the migration of interepithelial lymphocytes, macrophages, plasma cells, and tissue basophils to the surface epithelium increases. In both groups of experimental animals (and the II group of rats), lymphoid nodules and lymphoid pre-nodules of the gastric mucous membrane (GMM) are located between the bottom of the gastric glands and the muscular plate of the GMM. A gradual increase of medium lymphocytes in the GMM was established both in animals of I and II groups, while large lymphocytes increased in almost the same amount in experimental animals of both groups. Similar changes occur in the characteristics of the number of plasma cells, macrophages and tissue basophils in the lymphoid pre-nodules of GMM.
Conclusions: Administering monosodium glutamate to rats at a dose of 15 mg/kg of body weight for 2 weeks leads to an increase in the density and size of lymphoid structures of the mucous membrane in all parts of the stomach with a predominant increase in the number of immunocompetent cells between the bottom of the gastric glands and the muscle plate. At the same time, more pronounced changes were found in the number of small lymphocytes, which tend to decrease by the 2nd week of the experiment, and vice versa – their density increases by the 4th week of monosodium glutamate administration.