MORPHOMETRIC ANALYSIS OF NEUROCYTES OF THE CA3 REGION OF THE RAT HIPPOCAMPUS AFTER THERMAL INJURY WITH THE USE OF LYOPHILIZED XENOGRAFT
Authors: Nebesna Zoia , Lytvynyuk Diana , Ohinska Nataliia , Lytvynyuk Svitlana 
Published: October 2023

Abstract. The hippocampus has a complex structure, and its work is coordinated with other parts of the brain, helping to perform its main functions: memory, behavior, reaction to the surrounding world. The purpose of the study was to determine the dynamics of morphometric changes in neurocytes of the CA3 region of the rat hippocampus after experimental thermal injury using a cryolyophilized xenodermal substrate. Experimental studies were conducted on 56 sexually mature white male laboratory rats. The thermal injury was inﬂ icted under thiopental- sodium anesthesia with copper plates heated in boiled water.The area of the lesion was 18-20 % of the body surface. Early necrectomy of the damaged skin was performed 1 day after the thermal injury. The resulting wound was closed with a crushed substrate of lyophilized xeno-skin. The animals were decapitated on days 7, 14, and 21. Material for microscopic studies was collected according to the generally accepted method. The hippocampal histological preparations were used to determine the numerical density of CA3 neurons in the hippocampal region, the area of bodies and nuclei of diﬀ erent types of neurons, and their nuclear- cytoplasmic ratio. Statistical processing of digital data was performed using the software «Excel» and «STATISTICA 6.0» using parametric and nonparametric methods of data evaluation. A comparative analysis of the numerical density of neurocytes in the CA3 region of the hippocampus of animals with thermal injury and after correction showed that the number of cells that died was lower on day 7 after the use of lyophilized xenoceramics, but still not signiﬁ cant. On day 14, the number of sharply hypochromic neurocytes with total tigrolysis in its CA3 region was 1.7 times lower and the number of pycnomorphic, shriveled cells, respectively, 3.5 times lower than in the second control group of animals. The number of normochromic neurocytes in the hippocampal ﬁ elds increased by 1.40 times compared to the burned animals. They are characterized by normalization of the basophilic substance content and nuclei condition. Histological studies of hippocampal ﬁ elds on day 21 of the experiment showed that the use of xeno-skin to close burn wounds signiﬁ cantly normalizes their structural components. Microscopically, CA3 region at this time contained many normochromic neurocytes, 12.5 times (p<0.05) more than in animals with burns, respectively, 7.7 times fewer sharply hypochromic cells.Conclusions. Morphometrically, it was found that in the early period after thermal injury under the conditions of lyophilized xenodermal substrate application in the CA3 region of the hippocampus, the population of normochromic neurocytes increased by 1.43 times, the number of sharply hyper- and hypochromic forms decreased by 1.95 and 2.11 times compared to animals of the second group, indicating the onset of restorative, regenerative processes in the neurocyte- gliocyte-hemocapillary complex. Under the conditions of application of the corrective factor in the late period after thermal injury (14, 21 days), neurocyte recovery and normalization of their morphometric parameters were established. The content of normochromic neurocytes increases 1.40 times (14 days) and 2.94 times (21 days) in the CA3 region, compared to the parameters of the group of animals with thermal injury without correction, the content of sharply hypo- and hyperchromic cells signiﬁ cantly decreases, their nuclear- cytoplasmic ratios improve, which indicates the restoration of the morphofunctional state of CA3 neurocytes in the hippocampus.