Morphometric changes in the hippocampus and amygdala of mice in a model of chronic defeat stress

Under the influence of chronic stress, including social stress, a person can develop borderline states and mental illnesses. The mechanisms and morphological substrate underlying them are studied using animal modeling, including the paradigm of chronic social defeat stress. However, there are poorly developed aspects and inconsistencies in the literature that require clarification. Objective. To study morphological changes in the hippocampus and amygdala during chronic social defeat stress modeling in mice in comparison with control animals. Materials and Methods. The study was conducted in the paradigm of "chronic social defeat stress" using the previously described technique on linear mice (CBA/lac). Upon completion of the experiment, brain micropreparations stained according to Nissl were studied with visual and morphometric assessment. Results. The obtained results confirm that the substructures of the hippocampus and amygdala participate in the body's reactions to chronic social stress, which is manifested in changes in the morphometric characteristics of neurons. In the CA1 field of the hippocampus, an increase in the density of neurons is observed with minor atrophy of the cells themselves, while in the CA3 field, hypertrophy of neurons is revealed, mainly due to an increase in the volume of the cytoplasm, with a decrease in the folding of the cellular and nuclear membranes against the background of a slight average decrease in the density of neurons. In the lateral, basolateral and basomedial nuclei of the amygdala, atrophic changes in neurons are noted, which are not accompanied by significant changes in their density. Conclusion. The described morphometric data are consistent with a number of functional and biochemical changes that can cause them. At the same time, there are discrepancies that require further comprehensive study of the issue from the point of view of the morphofunctional approach.