The state of cognitive functions in cerebrovascular disorders is one of the most urgent healthcare problems. Recently obtained data convincingly indicate the participation of astrocytes in the formation of cognitive functions of the brain. We conducted a study on 88 Wistar rats. Following the results of testing the rats in a Morris water maze, all animals were divided into two subgroups: those with a high (HLA) and low (LLA) level of spatial situational learning abilities in the Morris water maze test. The animals in the experimental group (48 animals) underwent bilateral ligation of both carotid arteries. The animals were removed from the experiment on the 21st, 60th and 90th day after the operation. Glial fibrillar acidic protein (GFAP), a marker of mature astrocytes, was detected using primary polyclonal rabbit antibodies on histological sections of the precentral gyrus of the brain. Data were obtained on a more pronounced decrease in the numerical density of astrocyte bodies and the number of astrocyte main processes in HLA and LLA animals in earlier (on the 21st day) and later (on the 90th day) stages of the experiment, respectively. The growth of the area occupied by the astrocyte processes occurred earlier in HLA animals (on the 60th day after the simulation) compared to LLA animals (on the 90th day after the simulation). The conducted factor analysis confirmed the presence of two factors associated with the dynamics of the studied parameters. The conclusion is made about alternative variants of changes in the studied groups. The HLA subgroup predominantly demonstrated changes of an alterational character in earlier experimental stages, while adaptive changes were observed in the later stages of the experiment. Conversely, in the LLA subgroup, alterations and adaptations occurred in later and earlier experimental stages, respectively.

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Целью работы было установление нормативных показателей распределения астроцитов и нейробластов в ростральном миграционном потоке и в различных слоях обонятельной луковицы у крыс в эволютивном периоде по позитивности специфичных маркеров GFAP и DCX, а также выявление возможной корреляции между уровнями экспрессии GFAP и DCX. Материал и методы. Материалом для исследования служили обонятельные луковицы двадцати самцов крыс линии Wistar 30-, 60-, 90-, 180-суточного возраста, что соответствует инфантильному, ювенильному и зрелому возрастным периодам. Изучено распределение GFAP, маркера астроцитов, и DCX, маркера незрелых нейронов, в ростральном потоке и обонятельных луковицах в различных возрастных группах. Данные маркеры выявляли на парасагиттальных срезах с учетом слоев обонятельной луковицы. Определяли численную плотность GFAP+ астроцитов (шт/мм 2), площадь распределения их отростков, среднюю площадь тел, а также численную плотность DCX+ нейронов (шт/мм 2). Результаты. В результате исследования установлены возрастные нормативные показатели численной плотности астроцитов, медианной площади распределения их отростков и численной плотности незрелых нейронов, установлено наличие корреляции между экспрессией DCX и GFAP в ростральном потоке и гранулярном слое обонятельной луковицы. Согласно полученным данным, пик интенсивности постнатального нейрогенеза приходится на ювенильный возраст (60-90 суток), численная плотность нейробластов зависит от слоя луковицы и возраста животного. Численная плотность астроцитов также имеет топографические и возрастные особенности, площадь распределения отростков астроцитов изменяется противоположно их численной плотности. Полученные результаты являются основой для оценки реакции глии и стволовых ниш на разные виды воздействий. Ключевые слова: нейрогенез, обонятельная луковица, ростральный миграционный поток, астроциты, нейробласты, даблкортин, DCX, GFAP.

The aim of the study was to evaluate the morphological features of nNOS-positive (nNOS-IR) neurons in the dorsolateral cortex of the frontal lobe of the cerebral hemispheres in albino rats during 180 days of postnatal development.Material and methods. The study was performed on 40 outbred white Wistar rats of different ages, from 1 to 180 days. The object of the study was an area of the right cerebral hemisphere on the dorsolateral surface near the frontal pole (neocortex). On paraffin serial sections of the frontal lobe, an immunohistochemical reaction was performed with antibodies to nNOS and a detection system with horseradish peroxidase. Neuronal morphometry was performed by microphotographs using the ImageJ-Fiji (NIH) 1.51h program, measuring the sectional area of the  neuron   body,  the  area  of the  nucleus,  the  nuclear-cytoplasmic  ratio,  and  the  intensity  of the  reaction.The significance of differences was assessed by paired Student's t-test.Results. It was found that in mature rats in the frontal lobe cortex nNOS-IR was detected in large multi-polar cells with high activity of the enzyme located in the supragranular layers, spindle-shaped cells with long positive processes at the border with the white matter (type 1), and two varieties of low-positive neurons – accumulations in the VI layer and single ones in other layers (type 2). Polymorphism of nNOS-IR neurons manifests from the birth, but it was possible to distinguish all subpopulations only from the 21st day. Each subpopulation is distinguished by its own age dynamics of the studied parameters and the nature of the distribution of positivity. In addition, in 3–7 day old rat pups, numerous small neurons at the border of the cortex and white matter have transient immunoreactivity.Conclusion. Thus, the division of nNOS-IR neurons into two morphological types proposed in the works of predecessors does not correspond to the number of subpopulations that could be described in the dorsolateral region of the prefrontal cortex in rats. This diversity of nNOS-IR neurons is consistent with the numerous functions described for nitric oxide. For an objective characterization of various classes of nNOS-IR cortical interneurons, it is necessary to use additional data obtained from transcriptomic, histological, electrophysiological, and functional experiments, taking into account species, topographic, and age features. Only an extended approach will make it possible to selectively influence different types of cells and reasonably interpret the results of experimental studies.

Introduction. Physical activity is often used in rehabilitation to restore cognitive function after cerebral blood flow impairment and typological features like baseline cognitive ability may alter their effectiveness.The aim was to evaluate the expression of nNOS and NeuN in the large hemisphere cortex in the cerebral hypoperfusion occurrence in rats having different scores in the Morris maze.Materials and methods. Cerebral hypoperfusion was simulated by bilateral ligation of the common carotid arteries. Before surgery, Wistar rats were divided into equal subgroups with high (HCA) and low levels of cognitive ability (LCA) according to the results of Morris maze testing. Animals were removed from the experiment at 8, 21, 35, 60, and 90 days after surgery, a total of 184 rats, 24 formed the control group and 80 formed the cerebral hypoperfusion subgroup with 80 animals undergoing short-term swimming daily starting on day 7 of the experiment.Results. We revealed the earlier changes in HCA animals (8th day of the experiment) induced by cerebral hypoperfusion accompanied by a more intense nNOS-positive neurons density reduction to 47 % of control values, the length of their processes, and an increase in pericarion area. In LCA the decrease of density was only 75 % of control values and pericarion area does not differ from control values. At later periods on the 60 and 90 days of the experiment LCA demonstrates the preservation of the neurons density and greater length of their processes (67 % of the control subgroup values).Conclusion. HCA is a risk factor for damage of nNOS-positive neurons in cerebral hypoperfusion. Physical exercise more effectively decreases nNOS expression in animals with HCA, which may be one of the sanogenetic mechanisms of this factor.