Effect of calcium propionate on structural indicators of lymphatic nodes of rats receiving a high-fat diet

Calcium propionate is an organic compound that is an approved food additive for use in the food industry as a preservative to extend the shelf life of food. It is also used as an additive in dry pet food to help prevent spoilage and the growth of mold. As a dietary supplement, calcium propionate significantly reduces cardiac hypertrophy, fibrosis, vascular dysfunction and hypertension. It increases resting energy expenditure by promoting lipid oxidation and plays an important role in reducing eating behavior, lowering total blood cholesterol and reducing intestinal absorption. The experiment was designed to study the effect of calcium propionate at different concentrations, administered to the high-fat diet of experimental animals, on the changes in the absolute weight and the quantitative and qualitative parameters of the tissue components of the somatic and visceral lymph nodes. Four groups of outbred adult male rats were formed for the study. During the 20-day experimental period, animals in the control group consumed a high-fat diet only, while those in the experimental groups received varying amounts of calcium propionate in supplementation: 1–0,5 %, 2–1,0 %, 3–2,0 %. The stromal and parenchymal tissue components of the popliteal and circumflex lymph nodes were quantified and characterized. Morphological studies confirm the efficacy of calcium propionate in correcting a high-fat diet. In the lymph nodes of laboratory rats fed a high-fat diet, thickening of the capsule and trabeculae, an increase in the amount of adipose tissue, thickening and deformation of the walls of blood vessels and their excessive blood filling, degradation and partial destruction of deep cortex units, and dilation of the medullary sinuses were observed. This increased the volume of the medulla, which was more pronounced in the visceral lymph nodes. When the diet supplemented with 2.0% calcium propionate was consumed, the absolute weight of the lymph nodes in the test animals was the highest, especially the paracolic lymph node. There was an increase in the amount of parenchyma in the lymph nodes and a decrease in the amount of stroma. The relationship between structural and functional zones of the parenchyma changed, as evidenced by a decrease in the volume of the internodular cortex and an increase in the number of deep cortex units. There were also alterations in histological structure: thinning of capsule and trabeculae, reduction in adipose tissue volume, blood vessels became moderately blood-filled, the arterial wall was not thickened, narrowing of the medullary sinuses, and proliferation of deep cortex units.