AGE CHARACTERISTICS OF CHANGES IN THE LYMPHOID POPULATION STRUCTURE OF THE RATS’ THYMUS AFTER ACUTE DISTURBANCE OF CEREBRAL BLOOD FLOW IN THE BASIN OF CAROTID ARTERIES

Abstract

Abstract. Today, the most common causes of disability and mortality on the planet include acute disorders of cerebral blood circulation, the spectrum of which is dominated by ischemic lesions. Advances in neuroimmunology and neuroimmunopathology have made it possible to attribute cerebral blood circulation disorders to immune- dependent diseases of the nervous system, therefore, the emphasis in the search of new approaches to the eff ectiveness increase of stroke therapy has shifted from the correction of local changes in the brain itself to the reaction of the immune system organs, as a possible target of pharmacological eff ects, that will make it possible to reduce the secondary death of neurons as a result of infl ammation.The purpose of the work. to investigate the age-specifi c changes in the structure of the lymphoid population of the thymus after acute disruption of cerebral blood fl ow in the basin of the carotid arteries in six- and ninemonth-old rats.Material and methods. Acute cerebrovascular accident was simulated in 6- and 9-month-old white nonlinear laboratory rats by bilateral carotid artery clamping for 20 min. followed by reperfusion. The thymus was taken on the 12th day of the postischemic period, it was fi xed in Buen’s solution, after standard histological processing, serial sections with a thickness of 5 μm were made, stained with hematoxylin- eosin. In the subcapsular, deep cortical zones, intralobular perivascular spaces and the medullary zone of the thymus, the structure of the lymphoid population (density of diff erent classes of thymocytes per 1 mm2) was studied in the digital image analysis system VIDAS-386 (Kontron Electronik, Germany) with a fl uorescent microscope AXIOSKOP (Zeiss, Germany) in automatic mode.The results. In the structure of the lymphoid population of all structural and functional zones of the thymus, small lymphocytes predominate. Age-related diff erences in the structure of the lymphoid population of the thymus of the control groups consist of lower indicators of the density of medium and small thymocytes in all investigated zones of the gland of animals of the older age group, with the exception of the subcapsular, in which the density of small thymocytes is higher in nine-month-old rats. On the 12th day after simulation of ischemia- reperfusion of the brain injury the number of destructive thymocytes and thymocytes with the signs of apoptosis increases in the subcapsular and deep cortical zones of the thymus of six-month-old rats, but in nine-month-old rats in all zones of the gland, except the brain, the density of destructive and apoptotic cells decreases.Conclusions. Ischemic- reperfusion injury of the brain modifi es the structure of the lymphoid population of the thymus of rats, and the nature of these modifi cations is determined by age and structural and functional zones of the gland.