Structural Changes in Abdominal Aorta Wall at the Modeling of Long-Term Sympathicotonia on Laboratory Animals

This article considers topical issues of structural changes in the abdominal aorta wall in an experiment with prolonged sympathicotonia. The purpose of the study was to reveal the effect of prolonged sympathicotonia on the structure of rat's abdominal aorta wall in experiment. The studies were performed on two comparable groups of hundred-day Wistar rats which during 10 days experienced sympathicotonia with an increase in the activity of the sympathetic department of the ANS and the normal tone of the parasympathetic department of the ANS. The latter was achieved by the administration of α- and β- adrenomimetics of adrenaline tartrate, which action coincides with the excitation effect sympathetic nerve fibers. The first (control) group consisted of intact animals injected subcutaneously with 0.3 ml of a 0.9% solution of NaCl. The second (experimental) group involved rats, daily injected adrenaline tartrate subcutaneously at a rate of 0.05 mg•kg-1. The animals were removed from the experiment on the 10th day by decapitation in a state of anesthesia (calypsole at the rate of 16 mg•kg-1 of the animal mass intraperitoneally) and the abdominal aorta was isolated for histological examination. Histological preparations of the abdominal aorta were studied with an increase in x40, x100, x400 with the help of a Primo Star 5 microscope (Carl Zeiss, FRG) followed by photography of microscopic images. Computer morphometry was performed with x100 and x400 magnification and displaying the image on the computer monitor using the DVR and AxioVision image analysis software (Rel.4.8.2) in μm. The thickness of the subendothelial layer was studied with an internal elastic membrane and media. The ratio of the volume of the lumen of the abdominal aorta to the wall of the vessel was calculated in the Adobe Photoshop program by the method Glagoliev A.A. superposition of point grids into sections. The results were translated into percentages. Studies were carried out in five fields of five different sections in each rat. Based on the results of the variational analysis of the morphological study data, some features of restructuring the structure of the vascular wall of the abdominal aorta under the influence of prolonged sympathicotonia with an increase in the activity of the sympathetic department of the ANS and the normal tone of the parasympathetic department of the ANS have been revealed. In particular, prolonged sympathicotonia is a damaging factor that leads to degenerative changes in all the membranes of the abdominal aorta. However, the severity of these changes is ambiguous. While the local lesion of the endothelium and internal elastic membrane is noted in the intima, and the number of elastic fibers decreases and the structure and location of the smooth muscle cells are disrupted, the adventitial membrane undergoes maximum changes. In addition, the thinning of the subendothelial layer and the inner elastic membrane, and an increase in the percentage of the constituent of the vessel wall due to the constituents of other tissues, were found to be reliable, in comparison with the data in the control group. To understand the mechanisms of structural changes in the wall of the abdominal aorta in vegetative imbalance, additional studies are needed.