Cell cycle arrest in the thymus and spleen in male mice under conditions of chronic social defeat stress: effects of diazepam.

The effects of chronic social defeat stress on the percentage of cells in different phases of the cell cycle and in apoptosis in the thymus and spleen of male mice were studied by the method of flow cytofluorometry. In stressed males, thymus weight decreased, the percent of proliferating thymocytes was significantly lower, and the percentage of G0-G1 cells was higher than in intact males. Stress substantially reduced the percentage of splenocytes in the G0-G1 phase and apoptotic cells, but the percentage of S and G2-M cells and proliferation index significantly increased. Chronic administration of anxiolytic diazepam prevented the majority of the changes in the percentage of cells in different phases of the cell cycle, but apoptosis in the thymus increased under these conditions. Possible association between cell cycle disorders, impairment of cell immunity, and chronic anxiety developing under conditions of long-term social defeat stress is considered.