2023 年 12 巻 1 号 p. 65-73
Depending on brain tumor type, radiotherapy with various irradiation methods may be an effective treatment even for lesions for which surgical treatment is difficult; however, neurocognitive dysfunction may occur as an adverse effect. Neurons divide infrequently and are recognized as radiation resistant; however, few reports have investigated the effects of radiation on the intercellular network. We analyzed the impact of radiation exposure on the repair kinetics of DNA damage and the electrophysiological changes of synaptic currents in cerebral cortical neurons, employing primary culture technique. Cortical neurons (14 days in vitro) were subjected to varying X-irradiation doses. DNA double-strand breaks were induced in cultured cortical neurons by high-dose X-irradiation; however, these cells have the ability to repair severe DNA damage and are resistant to radiation. An electrophysiological investigation revealed that the inter-event intervals of miniature excitatory postsynaptic current (mEPSC) in X-irradiated cortical neurons were significantly longer, while the amplitude showed no change in comparison to 0 Gy-irradiated cells. These results suggested that the exposure of neurons to radiation led to a decrease in the frequency of the mEPSC, which affected the synaptic network, which supports the neurocognitive function despite being less likely to cause cell death or severe DNA damage.
