Effect of Long-Term Vagotonia on Structural Changes in the Wall of Abdominal Aorta During Immobilization Stress in Experimental Study

Abstract

This work covers current questions on studying structural changes in the wall of the abdominal aorta during the modelled long-term immobilization stress against vagotonia. The purpose of this study was to reveal the effect of prolonged vagotonia on the structure of the wall of the abdominal aorta in rats in the experiment. The studies were performed on three comparable groups of hundred-day Wistar rats, which were exposed to immobilization stress and vagotonia for a period of 10 days. Immobilization was chosen as a method to induce stress model. The rats were placed into a special plastic box, in this way limiting their movements for four hours at room temperature. Vagotonia was modelled by the administration of pyridostigmine bromide, reversible anticholinesterase. Histological preparations of the abdominal aorta were studied by x40, x100, x400 magnification using the Primo Star 5 microscope (Carl Zeiss, FRG) followed by photography of microscopic images. Computer morphometry was performed with x100 and x400 magnification and then the image were displayed on the computer monitor using the DVR and AxioVision image analysis software (Rel.4.8.2) in μm. We assessed the thickness of the subendothelial layer, and namely an internal elastic membrane and media. The ratio of the extent of the abdominal aorta lumen to the vascular wall was calculated in the Adobe Photoshop program by the A. A. Glagoliev method through overlaying of point grids on sections, the results were converted into percentages. The studies were carried out in five fields of five different sections in each rat. The results of the variation analysis of the morphological data obtained have revealed some features of restructuring the vascular wall of the abdominal aorta due to prolonged immobilization stress accompanied by vagotonia. It has been found out that prolonged exposure of hundred-day Wistar rats to immobilization stress leads to a decrease in thickness and certain morphological changes in all layers of the abdominal aorta wall and a decrease in the percentage of the component of the vessel wall. When accompanied by prolonged immobilization and vagotonia, preservation of the endothelial layer of the abdominal aorta was observed against the background of a decrease in intimal thickness and degenerative cell changes, as well as media thickening and focal changes in adventitia.