Serrano Céline, Dos Santos Morgane, Kereselidze Dimitri, Beugnies Louison, Lestaevel Philippe, Poirier Roseline, Durand Christelle
Laboratory of Experimental Radiotoxicology and Radiobiology (LRTOX), Research Department on the Biological and Health Effects of Ionizing Radiation (SESANE), Institute for Radiological Protection and Nuclear Safety (IRSN), 92260 Fontenay-aux-Roses, France.
Laboratory of Radiobiology of Accidental Exposure (LRAcc), Research Department in Radiobiology and Regenerative Medicine (SERAMED), Institute for Radiological Protection and Nuclear Safety (IRSN), 92260 Fontenay-aux-Roses, France.
Biology (Basel). 2021 Mar 4;10(3):192. doi: 10.3390/biology10030192.
The cognitive consequences of postnatal brain exposure to ionizing radiation (IR) at low to moderate doses in the adult are not fully established. Because of the advent of pediatric computed tomography scans used for head exploration, improving our knowledge of these effects represents a major scientific challenge. To evaluate how IR may affect the developing brain, models of either whole brain (WB) or targeted dorsal dentate gyrus (DDG) irradiation in C57Bl/6J ten-day-old male mice were previously developed. Here, using these models, we assessed and compared the effect of IR (doses range: 0.25-2 Gy) on long-term spatial memory in adulthood using a spatial water maze task. We then evaluated the effects of IR exposure on adult hippocampal neurogenesis, a form of plasticity involved in spatial memory. Three months after WB exposure, none of the doses resulted in spatial memory impairment. In contrast, a deficit in memory retrieval was identified after DDG exposure for the dose of 1 Gy only, highlighting a non-monotonic dose-effect relationship in this model. At this dose, a brain irradiated volume effect was also observed when studying adult hippocampal neurogenesis in the two models. In particular, only DDG exposure caused alteration in cell differentiation. The most deleterious effect observed in adult hippocampal neurogenesis after targeted DDG exposure at 1 Gy may contribute to the memory retrieval deficit in this model. Altogether these results highlight the complexity of IR mechanisms in the brain that can lead or not to cognitive disorders and provide new knowledge of interest for the radiation protection of children.
出生后大脑在低至中等剂量下暴露于电离辐射（IR）对成年个体认知方面的影响尚未完全明确。由于用于头部检查的儿科计算机断层扫描的出现，增进我们对这些影响的了解成为一项重大科学挑战。为了评估IR如何影响发育中的大脑，之前已建立了C57Bl/6J 10日龄雄性小鼠全脑（WB）或靶向背侧齿状回（DDG）照射的模型。在此，利用这些模型，我们通过空间水迷宫任务评估并比较了IR（剂量范围：0.25 - 2 Gy）对成年期长期空间记忆的影响。然后我们评估了IR暴露对成年海马神经发生的影响，这是一种与空间记忆相关的可塑性形式。WB照射三个月后，所有剂量均未导致空间记忆受损。相比之下，仅在DDG以1 Gy剂量照射后发现记忆检索存在缺陷，突出了该模型中的非单调剂量 - 效应关系。在此剂量下，在研究两个模型中的成年海马神经发生时也观察到了脑照射体积效应。特别是，只有DDG照射导致细胞分化改变。在靶向DDG以1 Gy剂量照射后成年海马神经发生中观察到的最有害效应可能导致该模型中的记忆检索缺陷。总之，这些结果突出了大脑中IR机制的复杂性，其可能导致或不导致认知障碍，并为儿童辐射防护提供了新的有价值的知识。
