Peculiarities of the effects of a high-calorie diet on the structural components of the lymph nodes and under melatonin correction

Obesity is a chronic recurrent disease that is manifested by excess accumulation of adipose tissue and is a consequence of an imbalance in energy utilization and consumption in persons with or without hereditary predisposition. The purpose of the study is to study the morphometric and histological changes of the parenchyma of the lymph nodes of rats in experimental obesity and under the conditions of melatonin correction. The study was performed on 66 white rats of reproductive age. Microanatomy of the structural components of lymph nodes of white rats under physiological norms was examined in 10 intact animals. Experimental animals were divided into 4 groups. Eight weeks after the experimental animals were on a high calorie diet (HCD), there was a significant decrease in the relative area of the cortical substance in the parenchyma of the lymph nodes of white rats of males and females by 10.3% and 8.3%, respectively, and an increase in the relative area of the medullary substance by 16.1% and 13.2%, respectively, compared to an intact group of animals. The relative area of the cortical substance in the parenchyma of the lymph nodes of white rats, which were for two weeks on HCD, then six weeks on HCD and melatonin, exceeds the parameters of the intact group of animals by only 3.2% in males and 3.5% in females. The relative area of the medullary substance is less than that of the intact group of animals by 5.0% in males and 5.5% in females. Under the conditions of melatonin correction it is found that the germinal centers of the secondary lymph nodes in the cortical substance are slightly increased. Trabecules extending from the capsule are clearly expressed and thickened, while arteries and arterioles show thickened walls and are full-blooded. Moreover, the veins are enlarged and full-blooded.