Department of Zoology, University of Mysore, Manasagangotri, Mysore, 570 006, India.
Immunobiology. 2019 Jan;224(1):133-141. doi: 10.1016/j.imbio.2018.09.007. Epub 2018 Sep 28.
The present study was undertaken to investigate whether or not chronic stress effect and its reversibility on lymphoid organs is duration dependent. Male rats were exposed to restraint (1 h) followed by a gap of 4 h to forced swimming exercise (15 min) daily for 2, 4 and 8 weeks. After each exposure period, rats were allowed to recover for 6 weeks. Stress exposure resulted in duration dependent decreases in weight of thymus and axillary lymph nodes, lymphocyte counts of spleen, thymus and axillary lymph nodes and number of islets of white pulp of spleen and increases in apoptotic index of splenocytes, thymocytes and lymphocytes of axillary lymph nodes. All the parameters of lymphoid organs studied showed significant alterations in 2 weeks of stress exposure indicated their sensitivity to stress effects in short term exposure and thymus was the most sensitive organ among all. The alterations in all the parameters of spleen and majority of parameters of thymus and axillary lymph nodes returned to control level in recovery group rats of 2 and 4 weeks exposure but not in that of 8 weeks exposure. The present study for the first time reveal that severity of stress effects on lymphoid organs increases with increasing duration of exposure and shorter the exposure period faster the recovery. In addition, an in vitro study showed that corticosterone caused apoptosis of thymocytes, splenocytes and lymphocytes of axillary lymph nodes in dose dependent manner. Thus corticosterone induced death of cells of lymphoid organs under stress is the major cause of involution of lymphoid organs.
本研究旨在探讨慢性应激及其逆转对淋巴器官的影响是否与持续时间有关。雄性大鼠每天接受 1 小时的束缚（1 小时），然后间隔 4 小时进行 15 分钟的强迫游泳运动，持续 2、4 和 8 周。每次暴露后，大鼠允许恢复 6 周。应激暴露导致胸腺和腋窝淋巴结重量、脾脏、胸腺和腋窝淋巴结淋巴细胞计数以及脾脏白髓胰岛数量随时间减少，而脾细胞、胸腺细胞和腋窝淋巴结淋巴细胞的凋亡指数增加。研究的所有淋巴器官参数在 2 周的应激暴露中都显示出显著的变化，表明它们对短期暴露的应激效应敏感，而胸腺是所有器官中最敏感的器官。在 2 周和 4 周暴露的恢复组大鼠中，所有脾脏参数以及大多数胸腺和腋窝淋巴结参数均恢复到对照水平，但在 8 周暴露的恢复组大鼠中则未恢复。本研究首次揭示，淋巴器官对应激的敏感性随暴露时间的延长而增加，暴露时间越短，恢复速度越快。此外，一项体外研究表明，皮质酮以剂量依赖的方式诱导胸腺细胞、脾细胞和腋窝淋巴结淋巴细胞凋亡。因此，应激下淋巴器官细胞的死亡是淋巴器官萎缩的主要原因。
