Morphological changes in the extraorgan vascular bed of the pineal gland of rats under conditions of chronic stress

Modern Ukrainian society has been in conditions of active military operations for several years, which have caused disruption of sleep patterns, lack of proper rest, and a sense of security, which has led to a state of chronic stress. The main role in protecting the body from stress factors, regulating sleep, and implementing adaptive reactions belongs to the pineal gland and the hormone it synthesizes – melatonin. However, prolonged exposure to stress factors leads to disruption of the functional activity of the pineal gland, which manifests itself not only at the cellular level but also in the state of the vascular bed. The aim of the work was to study morphological changes in the state of the extraorgan vascular bed and rheological properties of the pineal gland blood under conditions of chronic stress. The study was conducted on 12 adult white male Wistar line rats, which were divided into control and experimental groups. Animals in the control group were kept under normal vivarium conditions without the influence of additional factors. Animals in the experimental group were subjected to chronic stress by forced swimming for 60 minutes a day for 10 days. To study the state of the vascular bed of the pineal gland, morphological, morphometric, and statistical research methods were used. During the study, morphological manifestations of extraorgan blood circulation disorders in the pineal gland were detected, manifested by changes in the rheological properties of the blood and the restructuring of the walls of venous and arterial blood vessels. It was established that violations of the rheological properties of blood in venous vessels were manifested by blood separation, aggregation and lysis of erythrocytes and stasis, and in arterial vessels – by the practically absence of erythrocytes in the lumen of the vessels. Morphological changes in the state of the vascular wall in the veins were manifested by endothelial cell hypertrophy, stretching and thinning of the vascular wall, and its ruptures. In arterial type vessels, hypertrophy and edema of endothelial cells and spasm of muscle cell membranes were detected. Thus, the detected morphological changes indicate impaired blood circulation and slowing of blood flow, which leads to hypoxia of the pineal gland parenchyma.