Ultrastructural characteristics of the rats laryngeal mucosa and cartilage on the 7 and 14 days of the experimental opioid effect

Background and objective. Our main task was to study the ultrastructural organization of the laryngeal mucosa and cartilage on the seventh and fourteenth day of opioid exposure. Methods. The material for the study were mature, outbred male rats in the number of 32 animals, weighing 80g, aged 4.5 months. Animals were injected intramuscularly with Nalbuphine once a day at the same time (10-11 hours in the morning) for 14 days. The initial dose of Nalbuphine was 8 mg / kg during the first week, 15 mg / kg during the second week of the experimental study. Thus, we created the conditions for chronic opioid exposure. Animals were divided into 3 experimental groups: 1 – control group; 2 - animals that received the drug for 7 days; 3 - animals that received the drug for 14 days). All animals were kept in a vivarium. Animal care, labeling and all other manipulations were carried out taking into account the issues of bioethical norms. Before collecting necropsy material, the animal was removed from the experiment with diethyl ether. The the larynx mucosa and rats cartilage were used as the material for ultrastructural examination. Ultrastructural capsule was prepared according to conventional methods. Results. As a result of experimental opioid exposure at the end of 7 days we found alternative changes in the epithelial cells of different parts of the larynx, dyscirculatory changes in blood vessels of lamina propria and submucosa, as well as the destruction of chondrocytes of hyaline and elastic cartilages. The hemocapillaries of lamina propria and submucosa, especially in the ventricles of the larynx and in the subchondral region, were dilated, overflowing with erythrocytes. In the laryngeal mucosa and submucosal base of the laryngeal ventricles, in addition to the overflow of hemocapillaries with erythrocytes, a moderate accumulation of perivascular transudate was noted. At the end of the 14th day of the experimental opioid effect, a pronounced hemocapillaries injury was found, which was accompanied by an increase in the permeability of the vascular wall. In addition to blood plasma, erythrocytes were visualized in the enlarged lumens of hemocapillaries. The development of degenerative changes of endothelial cells, which were accompanied by inhomogeneous dilation of the tubules of the smooth and granular endoplasmic reticulum, was noted. The main substance of the connective tissue of the mucous membrane and submucosal base, especially around the vessels was impregnated with transudate.