Whole brain irradiation (WBI) therapy is an important treatment for brain metastases and potential microscopic malignancies. WBI promotes progressive cognitive dysfunction in over half of surviving patients, yet, the underlying mechanisms remain obscure. Astrocytes play critical roles in the regulation of neuronal activity, brain metabolism, and cerebral blood flow, and while neurons are considered radioresistant, astrocytes are sensitive to γ-irradiation. Hallmarks of astrocyte function are the ability to generate stimulus-induced intercellular Ca²⁺ signals and to move metabolic substrates through the connected astrocyte network. We tested the hypothesis that WBI-induced cognitive impairment associates with persistent impairment of astrocytic Ca²⁺ signaling and/or gap junctional coupling. Mice were subjected to a clinically relevant protocol of fractionated WBI, and 12 to 15 months after irradiation, we confirmed persistent cognitive impairment compared to controls. To test the integrity of astrocyte-to-astrocyte gap junctional coupling postWBI, astrocytes were loaded with Alexa-488-hydrazide by patch-based dye infusion, and the increase of fluorescence signal in neighboring astrocyte cell bodies was assessed with 2-photon microscopy in acute slices of the sensory-motor cortex. We found that WBI did not affect astrocyte-to-astrocyte gap junctional coupling. Astrocytic Ca²⁺ responses induced by bath administration of phenylephrine (detected with Rhod-2/AM) were also unaltered by WBI. However, an electrical stimulation protocol used in long-term potentiation (theta burst), revealed attenuated astrocyte Ca²⁺ responses in the astrocyte arbor and soma in WBI. Our data show that WBI causes a long-lasting decrement in synaptic-evoked astrocyte Ca²⁺ signals 12–15 months postirradiation, which may be an important contributor to cognitive decline seen after WBI.

全脑照射 (WBI) 疗法是治疗脑转移瘤和潜在的微观恶性肿瘤的重要方法。WBI 促进了一半以上幸存患者的进行性认知功能障碍，但其潜在机制仍不清楚。星形胶质细胞在神经元活动、脑代谢和脑血流的调节中起着关键作用，虽然神经元被认为是辐射抗性的，但星形胶质细胞对 γ 辐射敏感。星形胶质细胞功能的标志是能够产生刺激诱导的细胞间 Ca ²⁺信号，并通过连接的星形胶质细胞网络移动代谢底物。^{我们检验了 WBI 诱导的认知障碍与星形胶质细胞 Ca 2+}的持续损伤相关的假设信号和/或间隙连接耦合。小鼠接受了临床相关的分次 WBI 方案，在照射后 12 至 15 个月，我们证实与对照组相比存在持续性认知障碍。为了测试 WBI 后星形胶质细胞与星形胶质细胞间隙连接耦合的完整性，星形胶质细胞通过基于贴片的染料输注加载了 Alexa-488-酰肼，并使用双光子显微镜评估了邻近星形胶质细胞细胞体中荧光信号的增加感觉运动皮层的急性切片。我们发现 WBI 不影响星形胶质细胞与星形胶质细胞间隙连接耦合。星形胶质细胞 Ca ²⁺WBI 也未改变由去氧肾上腺素浴给药（用 Rhod-2/AM 检测）引起的反应。然而，用于长期增强（θ 爆发）的电刺激方案揭示了WBI 中星形胶质细胞乔木和体细胞中星形胶质细胞 Ca ^{2+反应减弱。我们的数据显示，WBI 会在照射后 12-15 个月导致突触诱发的星形胶质细胞 Ca 2+}信号长期下降，这可能是 WBI 后认知能力下降的重要原因。