Morphofunctional changes in the colon and immune responses during cold stress in male and female C57BL/6 mice

Introduction. Stress is one of the factors contributing to the gastrointestinal tract diseases development and exacerbating the course of diseases of the gastrointestinal tract. The cold factor is the most common stress factor in Russia. Therefore, the aim of our work was to characterize the immune responses and colon morphological and functional changes during cold stress in male and female C57BL/6 mice. Materials and methods. We studied alterations in the subpopulation composition of peripheral blood lymphocytes and morphofunctional changes in the thymus, spleen, and colon in response to a course intermittent cold exposure during 35-minute sessions for 14 days at –20° in adult male and female C57BL/6 mice. Results. The volume fraction of the PALS zone of the spleen and the content of endocrine cells in the colon decreased in animals of both sexes in the cold stress conditions. In females, the number of platelets and leukocytes in the peripheral blood increased, the width of the subcapsular zone of the thymus decreased, and the volume fraction of the red spleen pulp increased. In males, in the peripheral blood, the absolute and relative content of T-regulatory lymphocytes decreased, and the relative content of activated T-helpers increased, the volume fraction of the light centers of lymphoid nodules in the spleen decreased, the length of the crypts increased in the colon. A number of differences between males and females of control groups were also revealed: in the peripheral blood, males had more platelets and the absolute content of T-regulatory lymphocytes and less absolute content of T-cytotoxic. In the colon of males, the content of proliferating epithelial cells in the colon was higher than the one in females, and the bulk density of goblet cells was lower in males. Conclusion. Under the cold stress factor exposure in animals, physiological stress develops. Immune reactions and colon morphofunctional changes in the colon during cold stress differ between males and females. Keywords:cold stress, sex differences, colon, immune system