Gross N J, Narine K R, Wade R
Department of Medicine, Hines Veterans Administration Hospital, Illinois.
Radiat Res. 1988 Jan;113(1):112-9.
We explored the protective effect of corticosteroids on the mortality of mice that received thoracic irradiation. Methylprednisolone, 100 mg/kg/week, given from 11 weeks after gamma irradiation of the thorax resulted in an increase in the LD50 (11-26 weeks) from 14.3 +/- 0.3 (mean +/- SE) Gy to 17.6 +/- 0.4 Gy, P less than 0.001, a protection factor of 1.2. Withdrawal of steroids at various times during the period of radiation pneumonitis resulted in accelerated mortality in the next 2-4 weeks, so that the cumulative mortality "caught up" with that of control animals by 4 weeks after steroid withdrawal. However, after the end of the usual period of pneumonitis withdrawal of steroids did not result in accelerated mortality, suggesting that the time when steroids are protective corresponds to the duration of pneumonitis. A smaller dose of steroids, 25 mg/kg/week, was found to be as protective as the larger dose used in the above experiments. The possibility that corticosteroids reduce mortality, even when given many weeks after radiation, may have important practical and theoretical implications.
我们探究了皮质类固醇对接受胸部照射的小鼠死亡率的保护作用。从胸部γ射线照射后11周开始，给予甲泼尼龙，剂量为100 mg/kg/周，结果导致半数致死剂量（LD50，11 - 26周）从14.3±0.3（均值±标准误）Gy增加至17.6±0.4 Gy，P＜0.001，保护因子为1.2。在放射性肺炎期间的不同时间停用类固醇，会导致接下来2 - 4周内死亡率加速上升，以至于在停用类固醇4周后，累积死亡率“赶上”了对照动物。然而，在通常的肺炎期结束后停用类固醇并未导致死亡率加速上升，这表明类固醇具有保护作用的时间与肺炎持续时间相对应。发现较小剂量的类固醇，即25 mg/kg/周，与上述实验中使用的较大剂量具有同样的保护作用。即使在放疗数周后给予皮质类固醇，其仍可降低死亡率，这一可能性可能具有重要的实践和理论意义。
