致死剂量γ射线照射小鼠淋巴结淋巴细胞凋亡动力学及其与相关蛋白表达的关系

Apoptotic dinamic changes of mouse lymph node lymphocytes irradiated by lethal dose γ-irradiation and its relationship to the expressions of apoptosis-related proteins

用原位末端标记、原位杂交和碱磷酶免疫组化技术,观察致死剂量 γ 射线照射小鼠淋巴结淋巴细胞的凋亡动力学变化,及其与 Bax、Bcl-2 和 Bcl-XL表达的关系。结果表明,照射后 24h 淋巴结淋巴细胞凋亡指数迅速升高,在 6—12Gy 范围内与照射剂量呈正比,≥15Gy 照射后变化不明显。6Gy 照射后 24h,淋巴细胞凋亡达高峰,尔后开始降低;然而直至照射后 6 个月和 12 个月,凋亡指数仍明显高于对照组。6Gy 照射后 24h,淋巴细胞 Bax 蛋白表达即出现升高,当剂量为 12Gy 时达到峰值,15Gy 和 20Gy 照射后未观察到这种剂量效应关系。而 Bcl-2 和 Bcl-XL蛋白表达在照射后 24h 明显下降。bax 和 bcl-2mRNA 的表达显示出相似趋势。以上结果显示,≤12Gy 照射后细胞凋亡是淋巴细胞的重要死亡方式。照射后 Bax 的上调及 Bcl-XL 的下调在致死剂量照射引起的淋巴细胞凋亡调控中起重要作用。

By using TdT-mediated dUTP nick end labeling (TUNEL), in situ hybridization and immunohistochemical method of alkaline phosphatase, we observed the apoptotic dynamic changes of mouse lymph node lymphocyte after lethal dose γ-ray irradiation, and its relationship to the expressions of Bax, Bcl-2 and Bcl-XL proteins and bax, bcl-2 mRNAs.The results showed that 24h after irradiation, apoptotic index of lymph node lymphocytes increased swiftly, with a positive correlation to the doses within 6—12Gy, whereas no relationship was observed for 15Gy and 20Gy irradiation groups. Twenty-four hours after 6Gy irradiation, the lymphocytes apoptosis reached a maximal level and decreased thereafter. However, up to 6 and 12 months after the 6Gy irradiation, the apoptotic index was still higher than the control group. Twenty-four hours after the irradiation, the expression of lymphocyte Bax protein enhanced immediately, with the 12Gy group being highest value, whereas such a dose-effect was not found for the 15Gy and 20Gy groups. While the expressions of Bcl-2 and Bcl-XLproteins decreased evidently 24h after the irradiation, the analysis on bax and bcl-2 mRNA showed also a similar tendency. It was suggested that apoptosis was an important way of lymphocyte death pathways after ≤12Gy irradiation. The up-regulation of Bax and down-regulation of Bcl-2 or Bcl-XL indicate that they play an important role in the apoptotic regulation of lymphocytes induced by lethal dose radiation.