Histological changes in the adrenal glands of rats one hour after exposure to the venom of Leiurus macroctenus scorpions

The venom of scorpions of the genus Leiurus is considered among the most dangerous of known animal toxins, as its action can lead to severe systemic disorders and a high risk of fatal outcomes. The complex of biologically active substances that make up the venom is capable of affecting multiple target organs, including the cardiovascular, respiratory, and nervous systems. Particular attention is given to the impact of the toxin on endocrine glands, which play a key role in the formation of stress responses in the body. At the same time, morphological changes in such an important organ as the adrenal glands remain insufficiently studied, which highlights the need for further research in this area. The aim of the study was to determine the morphological changes in the adrenal glands of rats one hour after exposure to the venom of Leiurus macroctenus scorpions. Laboratory rats were divided into two groups: a control group (n=5), which received a single intramuscular injection of 0.5 ml of physiological saline, and an experimental group (n=5), which received a single intramuscular injection of 0.5 ml of Leiurus macroctenus venom. One hour after venom administration, the experimental rats were euthanized, and the adrenal glands were removed for subsequent histological analysis. After fixation in neutral formalin solution, standard dehydration was performed followed by paraffin embedding. Histological sections 4-5 μm thick were stained with hematoxylin and eosin and using the Azan Trichrome method. For a more detailed study of cellular structures, semithin sections 1-2 μm thick were prepared and stained with methylene blue. Microscopic analysis was carried out using a light microscope at magnifications of ×100 and ×400. Morphological analysis of the adrenal glands of rats one hour after inoculation with Leiurus macroctenus venom revealed pronounced vascular and cellular disturbances. In the cortical substance, dilation of small vessels, their deformation, and congestion with erythrocyte aggregation were observed. The zona fasciculata appeared the most vulnerable, showing signs of edema, disorganization of cellular structures, and karyopyknosis in the nuclei of endocrinocytes. In the zona glomerulosa, changes in nuclear shape and a chaotic distribution of heterochromatin were noted, suggesting damage to protein components of the karyoskeleton. The cytoplasm of endocrinocytes was filled with lipid inclusions, and cell boundaries became indistinct. In the zona reticularis, vascular disorders predominated, although the cells maintained a relatively preserved architecture. The medulla remained without significant pathological changes. Alterations in the capsule and interstitium confirmed the systemic nature of adrenal gland injury. Thus, Leiurus macroctenus venom induces early microcirculatory and cellular disturbances in the adrenal cortex, most pronounced in the zona fasciculata, while the medulla remains intact. The observed changes indicate a zonal specificity of the toxic effect.