Morphometric characteristics of changes in the retrosplenial cortex of mice during social stress modeling

Studies of the morphological substrate of stress effects on the organism help to understand the role of various brain structures in reactions to stressors, but the detailed mechanisms of these reactions remain poorly understood. Purpse. To study morphofunctional changes in the retrosplenial cortex, one of the important structures in the brain's reactions to stress, when modeling social stress in mice in comparison with intact animals. Materials and Methods. The study was performed on CBA (lac) mice in the paradigm of chronic social defeat stress for 20 days. After the animals were withdrawn from the experiment, micropreparations with Nissl staining, photofixation and qualitative and quantitative analysis with statistical processing were made from the brain material. Results end discussion. According to the morphometry results, there was a reliable increase in the perimeter of neuronal nuclei by 7.3 % (3.0–11.5 %) and the perimeter of perikarya by 9.5 % (5.1–14.0 %) in V layer of the granular retrosplenial cortex. However, these processes were accompanied by a decrease in the density of neurons with decrease in the relative areas of pericaryons by 16.5 % (8.7–24.3 %) and nuclei of neurons by 16.3 % (9.3–25.6 %). At the same time, there were opposite changes in the II/III layer of the agranular retrosplenial cortex in the form of neuron atrophy with a significant decrease in the area of the nuclei by 15.9 % (9.5–22.3 %), the perimeter of the nuclei by 7.8 % (4.5–11.1 %) and the perimeter of the pericaryons by 7.1 % (3.7–10.4 %), which also developed on against the background of a decrease in the density of neurons with a decrease in the relative area of their nuclei by 13.2 % (7.5–18.9 %). Conclusion. The obtained results are morphological evidence of the participation of the retrosplenial cortex in the body's response to chronic social stress of defeat in the form of reciprocal changes in its substructures.