BACKGROUND: Cholestasis refers to the stagnation of bile, leading to the release of its components into the blood, which has a toxic effect on various organs and systems, including the brain, and is accompanied by cognitive and behavioral disorders. The cingulate cortex is responsible for emotions, learning, and memory. Studies of this area of the brain will help understand the mechanisms of neuropsychiatric disorders in this pathology. Moreover, studying the cytoplasmic chromatophily of cingulate cortex neurons and the RNA content will help elucidate the morphofunctional state and severity of damage to neurons and their protein synthetic apparatus (ribosomes containing RNA). AIM: To examine the RNA content and cytoplasmic chromatophily of neurons in the cingulate cortex of the rat brain with cholestasis. MATERIALS AND METHODS: Neurons of the second parvocellular and fifth magnocellular layers of the anterior cingulate cortex of rats were evaluated at different times after ligation/transection of their common bile duct or sham operation (control). Histological, histochemical, morphometric, and statistical analyses were performed. RESULTS: Structural and histochemical changes in cingulate cortical neurons increase as cholestasis worsens in rats. Moreover, the number of normochromic neurons and shadow cells and hyperchromic, hyperchromic wrinkled, hypochromic neurons, and shadow cells increased, whereas the RNA content in the remaining neurons decreased. These changes reach a maximum of 10–20 days after the transection of the common bile duct. In surviving animals, in the preserved neurons of the cingulate cortex on days 45–90 after surgery, cytoplasmic chromatophily and RNA content are gradually normalized. Disturbances in the morphofunctional state of the neurons during cholestasis begin and end quite earlier in the small-cell than in the large-cell layer of the cingulate cortex. CONCLUSION: As cholestasis increases among the neurons of the rat cingulate cortex, the number of normochromic cells decreases, whereas the number of neurons with changes in cytoplasmic chromatophily and reduction in the RNA content increases. This indicates severe morphofunctional disorders of neurons and their protein-synthesizing capabilities. As cholestasis is eliminated, the studied parameters gradually normalized in the surviving neurons, which confirms the high adaptive capabilities of rat brain neurons.

The ultrastructural characteristics of neuron organellae are important indicators of the degree of brain damage during ischemic exposure, which necessitates the study of changes in the ultrastructure of brain neurons. Currently, there are no data on the severity degree of these disorders depending on the type of ischemic injury and its severity. These researches are relevant, as they allow us to study the nature of disorders of brain neurons at the ultrastructural level, depending on the severity of ischemia. Objectives. To study the nature of disorders of brain neurons at the ultrastructural level. Material and methods. Experiments were performed on 20 male rats weighing 260±20 g. Total cerebral ischemia was simulated by decapitation of animals, subtotal – by simultaneous ligation of both common carotid arteries. The material was taken 1 hour and 24 hours after the operation. The control group consisted of sham-operated rats of similar sex and weight. Results. There was a decrease in the size of mitochondria, disorganization of the cisterns of the endoplasmic reticulum and the Golgi complex, and an increase in the number of free ribosomes. At the same time, mitochondria became more rounded and less elongated. There was a decrease in the density and length of their cristae, which testifies to a decrease in the functional activity of mitochondria and the energy supply of neurons in the cerebral cortex. Conclusions. Both in total and subtotal cerebral ischemia, organellae are disorganized in the neurons of the parietal cortex and hippocampus, causing profound disturbances in energy production and metabolism.

Functional neurohistology is a field of morphological research that uses microscopic methods to assess the morphological support of the functions of brain structures, nerve tissue and nerve cells. These include classical histological methods, electron microscopy, histochemistry and immunohistochemistry in combination with morphometry. Each of the methodological approaches has its advantages and disadvantages. The choice of methods of functional neurohistology is determined by the specific objectives of the study. The review describes the methodological approaches used by us to assess the functional state of brain neurons in normal and pathological conditions. The advantages and necessity of using a complex of microscopic methods for a more complete assessment of the state of neurons are substantiated.

The ultrastructural characteristics of neuronal organelles are significant indicators of brain damage under ischemic exposure, which necessitates the study of changes in the ultrastructure of brain neurons. The aim of the study was to examine the disorders of brain neurons under its partial ischemia at the ultrastructural level using an experimental model. Materials and Methods. The experimental group included 12 male rats weighing 260±20 g, the control group consisted of 6 falsely operated male rats of the same weight. Partial cerebral ischemia (PCI) was modeled by right common carotid artery ligation. The material was taken 1 hour after the operation. Results. The study showed that the size and shape of the mitochondria of neurons of the parietal cortex and the hippocampus in PCI rats did not differ from those of the control group (p>0.05), except for a smaller number of cristae per unit area in the mitochondria of parietal cortex neurons (by 18 %, p<0.05). The size and shape of the Golgi complex and lysosomes did not differ in the groups either. However, there was an increase in the number of free ribosomes in the cytoplasm of neurons in the parietal cortex and hippocampus of PCI rats, by 58 % and 54 %, respectively (p<0.05). The ratio of fixed and free ribosomes in control rats decreased from 3.4 to 0.8 in the parietal cortex (p<0.05) and from 2.33 to 0.7 in the hippocampus (p<0.05). Conclusions. In general, the neuron ultrastructure in PCI rats was similar to that in the control group, which might be due to blood flow compensation in the circle of Willis. An increase in the number of free ribosomes is a sign of deranged protein biosynthesis in neurons. A decrease in the number of mitochondrial cristae in neurons in the parietal cortex indicates energy deficiency.

Neuroglobin (Ngb) is a member of the globin family. Like other globin proteins, it is involved in the maintenance of oxygen homeostasis. Ngb distribution in the normal brain is well known, but its response to pathological injury, such as cerebral ischemia, has not yet been adequately elucidated. One primary reason for this is that ischemic lesions in cerebral tissues have mostly been studied in transgenic organisms. In addition, the available data on Ngb content are limited to a small number of brain structures. This article examines the patterns of changes in Ngb immunoreactivity in neurons from different parts of the rat brain after subtotal cerebral ischemia of varying duration. An immunohistochemical study of Ngb content in 25 brain structures of white male Wistar rats exposed to 30-min and 3-h subtotal cerebral ischemia was performed. A decrease in Ngb content in all structures (especially 3 h after the ischemia onset and in the phylogenetically older parts), temporal mediation, and dependence on the phylogenetic age were revealed. The obtained results further decipher the correlation between the changes in Ngb content and the degree of cerebral ischemic damage, which is necessary to clarify the functions of the studied protein.

Доктор биологических наук, профессор А. А. Туревский был создателем современной кафедры гистологии, цитологии и эмбриологии Гродненского государственного медицинского университета и заведовал ею в течение 30 лет. А. А. Туревский был выдающимся педагогом, блестящим лектором и организатором учебного процесса на кафедре, создателем Гродненской гистологической школы. Он подготовил 3 докторов и 10 кандидатов наук, 22 года был научным руководителем студенческого научного общества. Его имя навсегда останется в памяти его учеников и истории Гродненского государственного медицинского университета.

Target. Analysis of changes in the morphological characteristics of neurons in such phylogenetically different parts of the rat cerebral cortex in different periods after total cerebral ischemia. Methodology. Experiments were performed on 42 male outbred white rats with an initial weight of 240±20 g. Total cerebral ischemia in outbred white rats was modeled by decapitation. The material was taken at the 1st, 5th, 15th, 30th, and 60th minutes, as well as 5 and 24 hours after decapitation. Results. With total cerebral ischemia, a significant decrease in the size of neurons and deformation of the perikarya were observed. Normochromic neurons completely disappeared at the 60th minute. The number of hyperchromic neurons increased and then progressively decreased. Shriveled neurons accounted for the majority of cells in the studied areas of the cortex at 30-60 minutes, and then, after 5 and 24 hours, cells with pericellular edema predominated in the neuron population. Conclusion. The obtained data on histological changes in neurons of phylogenetically different parts of the cerebral cortex in the dynamics of total cerebral ischemia provide the basis for further detailed study of post-mortem changes in the brain, determining the time of death, creating a fundamental basis for studying the properties of neurons, including their transition from one functional state to other.

Doctor of Biological Sciences, Professor A. A. Turevsky was the founder of the modern Department of Histology, Cytology and Embryology of Grodno State Medical University and was in charge of it for 30 years. A.A. Turevsky was an outstanding teacher, a brilliant lecturer and organizer of the educational process at the department, the founder of the Grodno Histological School. He trained 3 doctors and 10 candidates of sciences, for 22 years he was the scientific supervisor of the student’s scientific society. His name will forever remain in the memory of his students and history of Grodno State Medical University.

Ultrastructural characteristics of changes in neuronal organelles during two-stage ligation of the common carotid arteries in phylogenetically different sections are important indicators of the degree of brain damage during ischemic exposure, which necessitates the study of this aspect. Two-stage subtotal cerebral ischemia was performed on 24 outbred male rats by sequential ligation of both common carotid arteries with an interval of 7 days, 3 days and 1 day. This method of modeling subtotal ischemia makes it possible to study the dynamics of the consequences of severe cerebral ischemia and the pathogenesis of ischemic brain damage. Thus, compensatory changes in neuronal organelles during two-stage ligation of the common carotid arteries included expansion of the cisternae of the Golgi complex and hyperplasia of the endoplasmic reticulum, as a reflection of the activation of compensation mechanisms during hypoxia.

Introduction. ATP synthase is a key component of ATP synthesis. The study of its content in brain neurons in experimental cerebral ischemia may reflect changes in the functional state of different neurons and their sensitivity to the pathological effect. The study aimed to reveal patterns in ATP synthase immunoreactivity in neurons of various parts of the rat brain during subtotal ischemia of various durations. Materials and methods. Modeling of subtotal cerebral ischemia (SCI) was carried out by ligation of both common carotid arteries (n=12: control group – n=4, 30-minute SCI – n=4, 3-hour SCI – n=4); the control animals underwent a sham surgery. Frontal paraffin sections were stained according to the Nissl method to identify brain structures and immunohistochemically for ATP synthase. ATP synthase immunoreactivity was expressed in units of optical density ×103. Results. Changes in the immunoreactivity of ATP synthase in brain structures occur to varying degrees and not in all studied structures. The most pronounced and rapid decrease in the content of ATP synthase was observed in telencephalon, namely in the temporal and retrosplenial agranular cortex. The least pronounced changes in the cortex were in the structures of the hippocampus, in the neurons of layer II of the CA2 field. In the structures of the thalamus, hypothalamus, and midbrain the dynamic varied. In the structures of the medulla oblongata, the decrease in immunoreactivity occurs more slowly and less pronounced. Conclusion. During experimental cerebral ischemia the degree and rate of change in the content of ATP synthase in rat brain structures vary greatly and depend both on the brain region and the neurotransmitter nature of neurons. Keywords: ATP synthase, ischemia, immunohistochemistry, brain, rat

The recovery period after traumatic brain injury (TBI) is often complicated by secondary damage that may last for days or even months after trauma. Two proteins, Hsp70 and glyceraldehyde-3-phosphate dehydrogenase (GAPDH), were recently described as modulating post-traumatic processes, and in this study, we test them as targets for combination therapy using an inhibitor of GAPDH aggregation (derivative of hydrocortisone RX624) and an inducer of Hsp70 synthesis (the pyrrolylazine derivative PQ-29). The protective effect of the combination on C6 rat glioblastoma cells treated with the cerebrospinal fluid of traumatized animals resulted in an increase in the cell index and in a reduced level of apoptosis. Using a rat weight drop model of TBI, we found that the combined use of both drugs prevented memory impairment and motor deficits, as well as a reduction of neurons and accumulation of GAPDH aggregates in brain tissue. In conclusion, we developed and tested a new approach to the treatment of TBI based on influencing distinct molecular mechanisms in brain cells.

The relevance of the work is due to the wide spread of cerebrovascular pathology and ischemic strokes among the population. Most studies are devoted to the study of early brain damage in cerebral ischemia, while insufficient attention has been paid to the mechanisms of adaptation and long-term brain disorders. At the same time, delayed death of nerve cells in ischemia is not a predetermined and irreversible process, leaving opportunities for therapeutic intervention. There is a need to search for new data on the molecular and cellular mechanisms of damage development and compensatory processes in brain neurons in the dynamics of cerebral ischemia of varying severity. At the same time, the activation of compensatory mechanisms will reduce the severity of neurodegenerative disorders in the brain, increase the effectiveness of the treatment. An important role in the development of neurodegeneration is played by protein aggregates, which can be localized in nerve cells, in the intercellular space and cerebrospinal fluid. They are formed on the basis of damaged proteins, the violation of the structure of which can be caused by hypoxic and nitrosative stress, inflammatory processes provoked by ischemia, death of neurons. Therefore, an important role in preventing the development of secondary brain damage after ischemia can be played by cellular systems responsible for protein homeostasis, the protein synthesis apparatus, chaperones, the system of autophagy and elimination of damaged proteins ((ubiquitin, proteasome), as well as energy-intensive adaptation processes.

Introduction. The role of neuroglobin ischemia is still unclear. Some studies indicate its neuroprotective effect due to increased expression of endothelial NOS. Other evidence refutes its significance for neuronal survival under oxygen-deficient conditions, as neuroglobin deficiency appears to increase HIF-1α expression. Materials and methods. The experiments were performed on 56 male outbred white rats weighing 258±18 g. Total cerebral ischemia was simulated by decapitation of animals, whereas the subtotal one was simulated by simultaneous ligation of both carotid arteries. Stepwise subtotal cerebral ischemia was performed by ligating both carotid arteries with an interval of 7 days (subgroup 1), 3 days (subgroup 2), or 1 day (subgroup 3). Results. The study found significant differences in neuroglobin content across three subgroups. In subgroup 1, there was a notable increase in neuroglobin content compared to the control group, with a 13% increase in the parietal cortex (p<0.05) and a 14% increase in the hippocampus (p<0.05). However, subgroup 2 showed a decrease in neuroglobin content, with a 13% decrease in the parietal cortex (p<0.05) and a 7% decrease in the hippocampus (p<0.05). The most significant decrease in neuroglobin content was observed in subgroup 3, with a 31% decrease (p<0.05) in the parietal cortex and a 33% decrease (p<0.05) in the hippocampus. In subgroup 3, the parietal cortex showed a 40% decrease in neuroglobin content compared to subgroup 1 (p<0.05) and a 21% decrease compared to subgroup 2 (p<0.05). Similarly, the hippocampus exhibited a 42.6% decrease in neuroglobin content compared to subgroup 1 (p<0.05) and a 28% decrease compared to subgroup 2 (p<0.05). Conclusion. Thus, the most pronounced disorders of the prooxidant-oxidant balance decreased neuroglobin were observed during a 1-day total cerebral ischemia. Keywords: neuroglobin, ischemia, pyramidal neurons, hippocampus, parietal cortex

Background. Maternal cholestasis of pregnancy was found to have a negative effect on the kidney structure of firstgeneration offspring. It is not known whether changes in the urinary system will occur in second-generation offspring. Objective. To establish the peculiarities of kidney development in second-generation offspring from rats with cholestasis of pregnancy. Material and methods. Second generation 15-, 45- and 90 day-old rats born from males and females developed in maternal cholestasis. Surgical, somatometric, histological, morphometric and statistical methods of research were used in the experiment. Results. Maternal cholestasis induced on the 17th day of pregnancy leads to structural changes in the kidneys of second-generation offspring. These changes include a decrease in the weight of kidneys of experimental animals, a decrease in the width of their cortical substance, a decrease in the diameter of convoluted proximal and distal tubules of nephrons and the development of structural abnormalities in the epitheliocytes of tubule sections. Hypoplastic changes in renal nephrons persist up to 90 days of postnatal development of animals. Conclusions. Maternal cholestasis induces hypoplastic abnormalities in the kidneys of second-generation rats.

Introduction: The ultra-structural characteristics of neuron organelles are important indicators of the degree of brain damage during ischemic exposure, which necessitates the study of changes in the ultrastructure of brain neurons. Methods: Models of subtotal, stepwise subtotal, partial and total cerebral ischemia were carried out on 24 outbred white male rats. Electron microscopy methods were used. Results: The data obtained indicate that with total cerebral ischemia the disturbances are more pronounced than with partial cerebral ischemia and stepwise subtotal cerebral ischemia. Conclusion: The data obtained, due to their novelty and relevance; represent a fundamental basis for further studies of neurons in various parts of the brain during cerebral ischemia, with subsequent implementation of the results into clinical practice.

Введение. Изучение развития энергетического аппарата гистаминергических нейронов гипоталамуса в постнатальном онтогенезе представляет большой интерес, учитывая важность и недостаточную изученность этих клеток. Цель исследования. Выяснение постнатального развития энергетического аппарата гистаминергических нейронов мозга крысы. Материал и методы. Исследование выполнено на 5, 10, 20, 45 и 90-суточных беспородных белых крысах (72 крысенка). Проведена электронно-микроскопическая оценка изменения строения митохондрий, гистохимическое исследование активности ключевых окислительных ферментов этих нейронов и иммуногистохимическая оценка содержания в них АТФ-синтазы и нейроглобина. Результаты. Развитие энергетического аппарата гистаминергических нейронов в постнатальном онто- генезе сопровождается увеличением количества митохондрий и занимаемой ими относительной площади в цитоплазме, изменением их формы и увеличением в них длины крист. Изменения на ультрамикроскопическом уровне идут параллельно с метаболической дифференцировкой этих нейронов, включающей переключение с анаэробного на аэробный способ получения энергии, а также возрастание экспрессии АТФ-синтазы и нейроглобина, определяющих функциональное состояние энергетического аппарата данных клеток. Выводы. В постнатальном онтогенезе крысы происходит закономерное развитие энергетического аппарата гистаминергических нейронов мозга.

Aim. Comparative assessment of the distribution of ATP synthase and neuroglobin in neurons of different parts of the rat brain. Material and methods. The study was performed on the material from 5 outbred male rats. Immunohistochemical, cytophotometric and statistical research methods were used. Results. ATP synthase and neuroglobin are unevenly distributed at the regional and cellular level, the ratio of the content of these proteins varies significantly. Positive medium correlation exists between contents of these two proteins in different neurons, especially in phylogenetically older parts. The ratio of proteins does not depend on neurotransmitter nature of neurons, but depends on the position of neurons in reflex arc. Conclusions. The distribution ratio of ATP synthase and neuroglobin in brain neurons is characterized by a positive correlation and that indicates spatial and functional connections.

Catalase is an important antioxidant enzyme that destroys hydrogen peroxide formed in a result of normal cell metabolism, with the formation of water and oxygen, preventing lipid peroxidation of membranes and cell damage. This review analyses and summarises information about the history of discovery, structure, biogenesis, polymorphism and biological functions of cellular catalase.

Objective. Evaluation of changes in the content of ATP synthase in the parietal cortex and hippocampus of the brain of rats with ischemia of varying severity in a comparative aspect. Methods. The experiments were performed on 88 male outbred white rats weighing 260 ± 20 g. Brain ischemia was modeled under conditions of intravenous thiopental anesthesia (40-50 mg / kg). Total cerebral ischemia was modeled by decapitation of animals. The brain sampling was carried out 1 hour and 24 hours after decapitation - to study tissue respiration of mitochondria, as well as 1 hour later to determine the content of ATP synthase. Subtotal cerebral ischemia was modeled by simultaneous ligation of both common carotid arteries. The material was taken after 1 hour to determine the content of ATP synthase. Stepwise subtotal cerebral ischemia was performed by sequential ligation of both common carotid arteries with an interval of 7 days. The sampling was carried out 1 hour after ligation of the second common carotid artery in each of the subgroups. Partial cerebral ischemia was modeled by ligation of one common carotid artery on the right. The sampling was carried out 1 hour after the operation. Determination of the content of ATP synthase was carried out by immunohistochemical method using monoclonal antibodies. For this purpose, after decapitation, the brain was quickly removed from the rats, pieces of the cerebral cortex were fixed in zinc-ethanol-formaldehyde at + 4 ° C (overnight), then embeddedвinвparaffin. Results. In the group of stepwise subtotal cerebral ischemia, the smallest decrease in the content of ATP synthase was observed in the 1st subgroup with an interval between dressings of 7 days, while the greatest decrease in the content of the enzyme was noted in the 3rd subgroup with the minimum interval between the dressings of the common carotid artery (1 day). Modeling of more severe types of ischemic damage led to pronounced morphological changes in neurons in the parietal cortex and hippocampus of the rat brain - a decrease in their size, deformation of the perikarya, an increase in the degree of neuronal chromatophilia with their simultaneous wrinkling and subsequent death. These disorders were most pronounced in the 3rd subgroup of stepwise subtotal cerebral ischemia with the shortest interval between dressings, which was 1 day, and in the group of total cerebral ischemia. Conclusion. Thus, the most pronounced decrease in the content of ATP synthase was observed in the groups of total cerebral ischemia, subtotal cerebral ischemia and in the 3rd subgroup of stepwise subtotal cerebral ischemia, with a minimal time interval between the ligation of the common carotid artery. In stepwise subtotal cerebral ischemia with an interval between ligation of the common carotid artery of 7 days, the suppression of the ATP synthase content was not so significant.