Morphological changes in the bronchi and lung parenchyma of laboratory rats one hour after administration of Leiurus macroctenus scorpion venom.

Abstract

Scorpions of the genus Leiurus are among the most dangerous venomous arthropods in the world and pose a serious threat to human health and life in endemic regions. Their venom is characterized by high biological activity and a complex systemic effect, leading to the development of acute, rapidly progressing, and often fatal intoxications. Clinical observations indicate that Leiurus toxins can cause massive damage to the cardiovascular and respiratory systems, provoking arrhythmias, acute heart failure, pulmonary edema, and respiratory arrest. Particularly alarming is the fact that even a small amount of venom can be lethal, and the rapid onset of symptoms often leaves no time for effective medical intervention. Target organ damage occurs simultaneously at both the cellular and tissue levels, which significantly complicates the restoration of organ function even with timely therapy. Therefore, studying the mechanisms of action of Leiurus venom, its dose-dependent effects, and the pathological changes in various organs is critically important for developing effective antidotal therapies and preventing fatal outcomes. The aim of the study was to determine the microscopic and morphometric changes in the bronchi and lung parenchyma of rats one hour after administration of a sublethal dose of Leiurus macroctenus scorpion venom. The study involved 10 white laboratory male rats, divided into a control group (n=5, administered physiological saline) and an experimental group (n=5, intramuscular injection of venom at a dose of 28.8 μg/mL). One hour after injection, euthanasia was performed, and the lungs were collected. Samples were fixed in 10% neutral formalin, sectioned at 4-5 μm thickness (stained with hematoxylin and eosin and by the Azan Trichrome method), and semi-thin sections of 1-2 μm were prepared (stained with methylene blue). Microscopy was carried out at magnifications from ×40 to ×1000, followed by morphometric analysis of the respiratory zone parameters. Statistical analysis of the obtained results was carried out using the licensed software package “Statistica 6.0” with nonparametric evaluation methods. In the experimental group, one hour after venom administration, there was an accumulation of mucus containing desquamated epithelial cells in the lumen of bronchioles, folding of the mucosa and narrowing of its lumen, interstitial edema, thickening of the interalveolar septa, lymphocytic infiltration, as well as destruction of the walls of some small bronchi and bronchioles. Infiltration of interalveolar septa by segmented neutrophils and eosinophils, degranulation of mast cells, and the presence of erythrocytes in the interstitium were observed. Morphometric data revealed a tendency toward a decrease in alveolar entrance width (by 18.28 %), alveolar width (by 14.83 %), and conducting section width of respiratory bronchioles (by 3.15 %) compared with controls. Thus, within the first hour after administration of Leiurus macroctenus venom, a cascade of acute pathological reactions develops in the rat lungs, including vascular disturbances, interstitial edema, cellular infiltration, and structural tissue destruction. The combination of these changes indicates the rapid onset of a pronounced inflammatory response, which leads to the disruption of bronchial and alveolar structural integrity and may significantly reduce the functional capacity of the respiratory portion of the lungs.