Morphological Classification of Neuronal Damage

Objectives. To develop a morphological classification of neuronal damage for use in practical activities by researchers, pathologists, and forensic experts. Material and methods. The neurons of the cerebral cortex of 30 experimental animals (Wistar rats) were studied. Of these: with circulatory arrest N =10, with clozapine poisoning in combination with alcohol N =20 (clozapine dose 150 mg/kg, alcohol dose 5 ml/kg); morphological material of the human cerebral cortex was studied in subarachnoid hemorrhages (SAH) N =23, sudden cardiac death N =10, coronavirus infection N =18. Histological preparations were stained with hematoxylin and eosin, according to Nissl, according to Feulgen (for DNA), according to Brachet (for RNA and RNP), caspase-3 was detected by immunohistochemistry. Results. A morphological classification of neuronal damage was proposed, including: decentralization of the nucleus within a neuron, morphological changes in the nucleolus, dark neurons, chromatin remodeling, lipofuscinosis, neuronal edema, Nissl substance lysis, neuronal calcification, neuronophagia, necrosis, and neuronal apoptosis. Functional disorders that occur in the studied variants of neuronal alteration were considered. As a result of developing neuronal damage, the function of the neuronal cytoskeleton, synthesis of ribosome subunits, synthesis of ribonucleoproteins, and DNA reparation are impaired, apoptosis is activated, lysosomes are damaged, the formation of reactive oxygen species is activated, and irreversible forms of neuronal damage (neuronophagia, necrosis, apoptosis) are recorded. Conclusion. The proposed morphological classification complements existing classifications based on the study of molecular markers of neuronal damage and can be used in experimental studies and in the practical work of pathologists and forensic experts.