Chiang C S, McBride W H, Withers H R
Department of Radiation Oncology, UCLA Medical Center 90024-1714.
Radiother Oncol. 1993 Jun;27(3):229-36. doi: 10.1016/0167-8140(93)90079-n.
The goals of this study were to quantify myelin-associated changes in the brain following single doses of radiation and to determine their relationship to the dose limits that this tissue can tolerate. Mice developed a transient loss of balance 1 month after 60 Gy doses 250 kVp X-rays to the brain and 3-4 months after 30-45 Gy radiation, but not after lower doses. The symptoms were transient and lasted approximately 1 month. The ED50/300 for radiation-induced brain death, which occurred large between 200 and 240 days, was 32.4 Gy (29.1, 35.5 Gy, 95% confidence limit of mean). At the time that animals developed neurological symptoms, 3-4 months after irradiation with doses of 30-45 Gy, biochemical assays of myelin-associated proteins showed decreases in 2',3'-cyclic nucleotide phosphohydrolase (CNPase) and myelin basic protein (MBP) levels that were not seen with lower radiation doses. By 120-180 days, further dose-dependent decreases in both CNPase and MBP levels were found after 20-45 Gy irradiation that preceded and correlated with death. The correlation of the decrease in CNPase and MBP levels with the incidence of transient neurological malfunction and animal death, together with histological evidence, suggests that demyelination is responsible for these phenomena.
本研究的目的是量化单次辐射后大脑中与髓鞘相关的变化，并确定它们与该组织可耐受的剂量限值之间的关系。给小鼠脑部单次给予250 kVp的60 Gy X射线辐射后1个月，以及30 - 45 Gy辐射后3 - 4个月，小鼠出现短暂的平衡失调，但较低剂量辐射后未出现这种情况。这些症状是短暂的，持续约1个月。辐射诱导脑死亡的ED50/300（发生在200至240天之间）为32.4 Gy（29.1，35.5 Gy，均值的95%置信区间）。在用30 - 45 Gy剂量进行辐射后3 - 4个月动物出现神经症状时，对与髓鞘相关蛋白的生化分析显示，2',3'-环核苷酸磷酸二酯酶（CNPase）和髓鞘碱性蛋白（MBP）水平下降，而较低辐射剂量时未出现这种情况。到120 - 180天时，在20 - 45 Gy辐射后发现CNPase和MBP水平进一步出现剂量依赖性下降，这先于并与死亡相关。CNPase和MBP水平下降与短暂神经功能障碍和动物死亡发生率之间的相关性，以及组织学证据表明，脱髓鞘是这些现象的原因。
