长期递增负荷运动对胸腺细胞凋亡及其细胞周期调控蛋白的影响

Effects of Long-term Incremental Exercise on Thymus Cell Apoptosis and Cell cycle Regulatory Proteins

目的：观察6周递增负荷运动过程中,大鼠胸腺结构、胸腺细胞凋亡蛋白、胸腺细胞周期调控蛋白的变化特征。方法：雄性SD大鼠80只随机分为安静组和运动组,运动组进行6周递增负荷跑台运动,分别于第0、2、4、6周运动完成后通过HE染色观察大鼠胸腺组织形态,通过免疫组织化学技术测定胸腺细胞凋亡蛋白bax、bcl-2及细胞周期蛋白cyclinE、cyclinB1与细胞周期抑制蛋白p21的表达。结果：1）大鼠胸腺细胞密度下降,皮、髓质融合,网状结构破坏并出现脂肪细胞及血细胞;2）与0周组相比,2周组、6周组Bax/Bcl-2比值均显著增加（P〈0.01）;与2周组相比,4周组、6周组显著减少（P〈0.01）;6周组较4周组显著增加（P〈0.01）;3）细胞周期G1/S期调控蛋白cyclinE表达0~2周上升（P〉0.05）,4周时较0、2周急剧下降（P〈0.01）,6周较4周显著提高（P〈0.05）;细胞周期抑制蛋白p21表现出2周时显著上升（P〈0.01）,4周时下调（P〉0.05）,6周略有回升（P〉0.05）的变化趋势,4、6周p21表达量较2周差异非常显著（P〈0.01）;G2/M期调控蛋白cyclinB1表达呈先上升后下降的变化趋势,差异不具有显著性（P〉0.05）。结论：6周递增负荷运动过程中,大鼠胸腺组织结构发生渐行性破坏;Bax/Bcl-2比值呈现上升、下降再上升的变化特征,大鼠胸腺细胞凋亡增加以Bcl-2的变化为主导;大鼠胸腺细胞周期G1/S期调控蛋白较G2/M期调控蛋白受递增负荷运动影响更显著。长期递增负荷运动可能主要通过在G1/S期造成DNA复制障碍,阻滞胸腺细胞周期运转。细胞周期阻滞可能是胸腺细胞凋亡发生的原因之一。

Objective：To observe the variation characteristics of the thymus structure,the apoptosis proteins and the cell cycle regulatory proteins during long-term incremental exercise.Methods：80male SD rats divided into control group and exercise group randomly.The exercise group participated in six weeks incremental treadmill training.The thymus structure were observed by HE staining,the expression of bax and bcl-2,cyclinE,p21 and cyclinB1of thymus cell were detected by immunohistochemistry at 0week,after 2weeks exercise,4weeks exercise and 6weeks exercise.Results：1）The cells density of thymus decreased,the cortex and medulla of thymus lobule became fused,reticular formation in thymocytes were destructed,adipocytes and hemocytes occurred.2）Compared with WK0,bax/bcl-2increased significantly in WK2 and WK6（P〈0.01）.Compared with WK2,it decreased with a significant difference in WK4 and WK6（P〈0.01）.While the ratio increased again in WK6 than in WK4（P〈0.01）.3）Compared with WK0,CyclinE increased slightly in WK2（P〉0.05）.While it reduced significantly in WK4 compared with WK0 and WK2（P〈0.01）.Compared with WK4,WK6 increased with a statistical difference（P〈0.05）.Making the p21 expression in WK0 as a reference,p21 extremely increased in WK2（P〈0.01）.Compared with WK2,WK4 reduced drastically（P〈0.01）.The expression slightly increased in WK6,but still less.The expression of CyclinB1 in rat thymocytes in WK2 was higher than WK0,and it reduced in WK4.Compared with WK4,the expression in WK6 increased slightly.The expression of CyclinB1 changed smoothly among every week and there was no significant difference（P〉0.05）.Conclusion：During six-week incremental exercise,the structure of rat thymus was destructed gradually.Bax/bcl-2in thymus of rats shows a trend that increased firstly and then decreased,and finally increased again.The apoptosis of thymocytes increased and the changes of bcl-2led this thymocyte apoptosis.The effect of the expression of thymus cell cycle regulatory proteins in G1/S by incremental exercise is more obviously than that in G2/M.The block of thymus cell cycle due to long-term incremental exercise mainly because of the DNA replication disorder which caused by the regulation of G1/S phase.Cell cycle arrest may be one of the mechanisms of thymocyte apoptosis.