Morphofunctional Characteristics of the Hippocampus of White Rats in the Acute Period After Severe Traumatic Brain Injury During the Use of L-lysine Aescinat
Authors: Koshman I. P. , Shoronova A. Yu. , Stepanov S. S. , Kalinichev A. G. , Akulinin V. A. , Stepanov A. S. , Avdeyev D. B. , Molchanova V. L. 
Published: January 2021

Aim of study. The study is devoted to the effect of L-lysine aescinat on the nervous tissue of the CA1 and CA3 fields of the hippocampus of the brain of white rats in the acute period after severe traumatic brain injury (TBI).

Material and methods. TBI was simulated by applying a blow to the parieto-occipital region with a freely falling weight weighing 200-250 grams from a height of 50 cm using a special rail rack. The objectives of the study were: 1) comparative morphometric assessment of the degree of hydration, cyto- and glioarchitectonics of different layers of CA1 and CA3 fields after ischemia without treatment; 2) the effect of L-lysine aescinat on these indicators. We used histological (staining of sections with hematoxylin-eosin and Nissl), immunohistochemical (for NSE, MAP-2 and GFAP) and morphometric methods. On thin (4 μm) serial frontal sections of the hippocampus, neurons, astrocytes, microvessels and neuropiles were studied in control (intact animals, n=5) and 1 and 3 days after injury without treatment (n=10, comparison group) and with treatment ( n = 10, main group). The number density of neurons was determined using the Nissl staining of cells and by the reaction to NSE. The cytoskeleton of neurons was studied by detecting MAP-2, and astroglia by GFAP. On color raster images (staining with hematoxylin and eosin, x100) using the Find Maxima plug-in filter, the zones of maximum brightness were determined, which were then analyzed using Analyze Particles from the ImageJ 1.52s program. Zones of maximum brightness corresponded to areas of the hippocampus with a high degree of hydration of the nervous tissue - edema-swelling. The nature of the distribution, statistical hypotheses, and plotting were checked using Statistica 8.0 software and R environment.

Results. In control animals, normochromic neurons without signs of changes in the cytoskeleton prevailed in all layers of fields CA1 and CA3, and a low degree of hydration of the nervous tissue was noted (the relative proportion of zones of maximum brightness was 5–8%). One and 3 days after TBI, there was a statistically significant increase in the focal content of dystrophic and necrobiotically altered neurons (95% confidence interval: 52–78%), manifestations of reactive gliosis were noted, and the proportion of zones of maximum brightness increased to 16%. Statistically significant layer-by-layer differences were revealed between the CA1 and CA3 fields of the hippocampus. The use of L-lysine aescinat had a statistically significant effect on the morphometric parameters of the nervous tissue of the hippocampus.

Conclusion. In the early post-traumatic period after TBI, the degree of hydration of the nervous tissue of the hippocampus increased. Heteromorphicity of dystrophic and necrobiotic changes in different layers of CA1 and CA3 fields was noted. L-lysine aescinate had a statistically significant positive effect on these changes. To a greater extent, this is typical for the CA3 field. The revealed changes are considered not only as patho-, but also as sanogenetic structural mechanisms of protection and reorganization of the hippocampus in the acute post-traumatic period.

1. In the acute period (1−3 days) after severe traumatic brain injury, the degree of hydration of all components of the hippocampal nervous tissue increased. In the group without treatment, 3 days after injury, the relative volume of edema-swelling zones varied from 10 to 13% in CA1 (control 3-7%) and from 8 to 16% in CA3 (control 5–10%).

2. The heteromorphism of hydropic changes in the molecular layer, the layer of pyramidal neurons and the polymorphic layer was established. The maximum increase in the volume of free water (more than twofold) was characteristic of the molecular and polymorphic layer CA1, as well as the polymorphic layer CA3.

3. The use of L-lysine aescinat in the acute period significantly changed the manifestations of hydropic dystrophy. One day after injury, the volume of free water increased in comparison with animals without treatment, and then, after 3 days, decreased, but remained higher than in the comparison group. The maximum effect of the drug was noted in field CA3.