Morphological changes of the thymus under stress caused by water immersion and restraint in SAMP1 mice

• Published in: International Congress series 2004-02, Vol.1260, p.199-202
• Main Authors: Miyamoto, Mari Shimbo, Miyamoto, Yohei, Hosokawa, Tomohide
• Format: Article
• Language: English
• Subjects: Apoptosis; Macrophage; Morphological change; Pyknotic cell; Regeneration; Stressor
• ISSN: 0531-5131; 1873-6157
• DOI: 10.1016/S0531-5131(03)01568-1

We compared the time course of the stress-induced morphological changes in the thymus between SAMP1 and C3H/He mice. The mice were kept under restraint in a 50-ml plastic centrifuge tube in water at 24° for 4 h. This treatment induced atrophy of the thymus and reduced the thymus weight, although it did not affect the body weight or major organ weights in either strains of mice. Histological studies of the thymus revealed that the stress groups of both strains showed a transient increase in the number of pyknotic cells and macrophages as compared with each control group just after the stressor treatment. Only a slight increase in the macrophage number was found at 4 h after the treatment. Furthermore, we investigated the morphological changes of the thymus until 7 days after the treatment, in order to compare the time course of recovery of the thymus atrophy between the two mouse strains. The stress groups of both strains had decreased lymphocyte populations in the thymus. The thymic lymphocyte population in C3H/He mice started to recover at 24 h after the stressor treatment. In clear contrast, the lymphocyte population in the SAMP1 thymus did not recover but continued to decrease until 7 days after the treatment, being progressively replaced by fibroblasts. These results suggest that the regenerative mechanisms of the SAMP1 thymus have some defects, and that the T-cell compartment of the immune system in SAMP1 mice may be as sensitive as aged mice from the control strain.