(PQ9) Directed and unbiased studies of synaptic injuries as sequelae of radiotherapy: mapping, sex-dependence, and reversal

摘要 脑癌是一种可怕的诊断，在儿童癌症中占了相当大的一部分，但 由于治疗方面的巨大进步，儿童存活率现已超过80%。这些阳性的临床 结果需要使用放射治疗(RT)，但像其他治疗方式一样，RT会导致显著的长期- 长期神经认知后遗症不仅影响癌症幸存者，还影响他们的照顾者网络和 社会。接受脑癌RT治疗的成年人也会出现类似的症状，并将受益于 改善或消除RT的神经认知效应。从理论上讲，RT诱导的脑损伤更容易 在损伤时间已知且预处理可行的情况下，治疗脑损伤优于其他脑损伤。然而， 放射治疗引起的脑损伤的性质尚不清楚，这是做到这一点的主要障碍。RT诱导脑损伤的研究进展 损伤主要集中在神经前体(NP)细胞的分裂上，从这些细胞中，出生后的一小部分成年- 与生俱来的神经元出现在齿状回，就像海马体(齿状回是其中的一部分)一样。 对辐射特别敏感的。当然，NP细胞的损伤导致了RT诱导的后遗症。然而， 我们和其他人最近表明，终末分化的神经元，长期以来被认为是抵抗 辐射，经历突触变化对辐射的反应。这一观察结果对 治疗放射治疗引起的后遗症，因为它表明损害可能发生在整个 而不限于出生后神经元形成的小而不连续的部位。在这份提案中，我们提出 我们关于这一现象的最新数据显示，治疗性剂量的辐射会导致异位 RT后1小时内突触发生和突触增强。女性比男性受此影响更大。 侮辱和抑制谷氨酸信号可阻止突触扩张和随后的长期 突触丢失。然而，许多问题仍然没有得到回答：受伤的部位有多大？伤势会不会 沿着神经元回路传播？大脑的某些区域是更容易受到伤害还是更不容易受到伤害？多么 这些参数是否受接受RT的个体的性别的影响？RT介导的突触缺陷 被颠倒了？这些关键问题的答案是合理设计抗击疗法所必需的。 RT诱导的神经认知后遗症。我们建议定义急性RT诱导的突触损伤的性质 通过(I)使用神经元荧光探针建立RT介导的小鼠脑内突触损伤的图谱 活动和突触增强，先进的成像技术和多维分析，(Ii)测试 年龄和性别对受试者RT反应的影响，以及(Iii)操纵细胞信号试图 逆转录酶介导的突触损伤。我们提出了一种新的、多学科的方法来解剖 RT介导的突触损伤在分子、突触、细胞和器官上的性质，即行为， 级别。这项翻译建议的结果有可能极大地积极影响 所有年龄段的癌症幸存者，我们的技术可以用于调查其他类型的脑损伤。

Abstract Brain cancer is a terrifying diagnosis representing a relatively large segment of childhood cancer, yet thanks to great advances in treatment, survival rates among children now exceed 80%. These positive clinical outcomes require the use of radiotherapy (RT), but like other treatment modalities, RT causes significant long- term neurocognitive sequelae impacting not only cancer survivors, but also their caregiver networks and society. Adults receiving RT for brain cancers also suffer similar symptoms and would benefit from the amelioration or elimination of the neurocognitive effects of RT. In theory, RT-induced brain injury is easier to treat than other brain injuries, given that the time of injury is known and pretreatment is feasible. However, the unclear nature of RT-induced brain damage is a major obstacle to doing so. Research on RT-induced brain injury has focused on the dividing neuroprogenitor (NP) cells from which a small pool of postnatal, “adult- born” neurons arises in the dentate gyrus, as the hippocampus (of which the dentate gyrus is part) is particularly sensitive to radiation. Certainly, NP cell damage contributes to RT-induced sequelae. However, we and others have recently shown that terminally differentiated neurons, long thought to be resistant to radiation, undergo synaptic alterations in response to radiation. This observation has major implications for the treatment of RT-induced sequelae because it suggests that the damage could happen throughout the entire brain and not be limited to the small, discrete sites of postnatal neuron formation. In this proposal, we present our most recent data on this phenomenon, showing that therapeutic doses of radiation lead to ectopic synaptogenesis and synapse potentiation within 1 hr of RT. Females are more affected than males by this insult, and suppressing glutamate signaling prevents both synapse expansion and subsequent long-term synapse loss. Many questions remain unanswered, however: How localized is the injury? Does the injury promulgate along neuronal circuits? Are some regions of the brain more or less susceptible to the injury? How are these parameters affected by the sex of the individual undergoing RT? Can RT-mediated synaptic defects be reversed? These are critical questions whose answers are required to rationally design therapies to combat RT-induced neurocognitive sequelae. We propose to define the nature of acute RT-induced synaptic damage at by (i) creating at atlas of RT-mediated synaptic injury in the mouse brain using fluorescent probes for neuronal activity and synaptic potentiation, advanced imaging techniques and multidimensional analysis, (ii) testing the influences of age and sex on subject response to RT, and (iii) manipulating cellular signaling to attempt to reverse RT-mediated synaptic damage. We propose a novel and multidisciplinary approach to dissecting the nature of RT-mediated synaptic damage at the molecular, synaptic, cellular, and organismal, i.e. behavioral, levels. The results of this translation proposal have the potential to greatly and positively impact the health of cancer survivors of all ages, and our techniques could be used to investigate other types of brain injuries.