Changes in the Cellular Composition of the Cerebral Cortex in Rats with Different Levels of Cognitive Function in Cerebral Hypoperfusion Combined with Short-Term Physical Activity

Abstract

The aim of the study was to detect the features of neurodystrophic changes in neurons and glia of the motor cortex of the brain in rats with different levels of cognitive functions and stress resistance with bilateral ligation of the common carotid arteries combined with short-term physical activity.Material and methods. The study included 136 Wistar rats. All animals were divided into two subgroups depending on the results of testing in the Morris water maze: with a high and a low level of abilities for spatial environment learning. Animals of the experimental group were exposed to daily free swimming for 15 minutes, starting on the 7th and ending on the 35th days of the study. The rats were withdrawn from the experiment in 8, 14, 21, 35, 60, and 90 days after bilateral ligation of both carotid arteries. Histological sections of the precentral gyrus of the brain were stained according to Nissl and hematoxylin-eosin.Results. On the 8th day of the experiment (1 day of short-term physical activity), the hemomicrocirculatory bed of the cerebral cortex was characterized by a decrease in venous hyperemia, and a decrease of tissue edema signs around the hemocapillaries, a characteristic feature of isolated cerebral hypoperfusion. Neurons with signs of hyperfunction and rod-shaped inclusions in the nuclei (Roncoronni bodies) were detected on the 14th, 21st, 28th days. Hemocapillaries formed compact groups of cells. Further, neurodystrophic changes were less pronounced in comparison with isolated cerebral hypoperfusion, this was accompanied by a decrease in venous hyperemia, preservation of perivasal cell groups up to the 60th day of the experiment. Roncoroni bodies disappeared on the 90th day of observation.Conclusion. The effect of short-term physical activity on the development of cerebral hypoperfusion resulted in an increase in the number of neurons without irreversible changes, a decrease in neurodegenerative changes, and also reduced the severity of gliosis. The adaptive effect of short-term physical activity was more pronounced in animals with a high level of cognitive abilities, which was accompanied by a more significant decrease in the number of dead cells of the cerebral cortex. Day 28 was a critical point when gliosis and neuronal death were combined with the appearance of Roncoronni bodies and perikarion hypertrophy of some pyramidal neurons, as well as the concentration of gliocytes around hemocapillaries. The latter appears to be a sort of adaptation, since it is accompanied by a decrease in mortality in animals with a high level of cognitive abilities.