Abstract: BACKGROUND: Radiation-induced brain injury, as one of the serious complications after radiotherapy, seriously endangers people's health and damages learning and memory functions. However, there are relatively few reports on the prevention and treatment of brain damage caused by electroacupuncture intervention.
OBJECTIVE: To explore the effect of electroacupuncture intervention on the expression of synaptic plasticity related proteins in mice with radiation-induced brain injury. 
METHODS:  C57BL/6J mice, 30 days old. were randomly divided into blank group, model group and electroacupuncture group. Except for the blank group, the other groups were given 8 Gy radiation dose to construct a radiation-induced brain injury model. The electroacupuncture group was given acupuncture at “Baihui” (GV 20), “Fengfu” (GV 16) and bilateral “Shenshu” (BL 23) for 21 days for intervention, and mice were intraperitoneally injected with BrdU. After electroacupuncture, Morris water maze test and T maze test were used to detect the learning and memory abilities of mice. Immunohistochemical method was used to detect the expression of BrdU in the hippocampus. Western blot assay was used to detect Notch1 and Hes1 related to Notch signaling pathway in the hippocampus, and synaptic plasticity-related proteins synaptophysin (SYN), postsynaptic density protein-95 (PSD-95) and brain-derived neurotrophic factor (BDNF) expression. 
RESULTS AND CONCLUSION: Electroacupuncture intervention significantly improved learning and memory impairment in mice with radiation-induced brain injury. The positive expression of BrdU in the model group was significantly lower than that in the blank group (P < 0.01), and the positive expression of BrdU in the electroacupuncture group was significantly increased (P < 0.01). The expression levels of Notch1, Hes1, PSD- 95, SYN and BDNF were lower in the model group than that of the blank group (P < 0.01, P < 0.01, P < 0.01, P < 0.05, P < 0.01). Compared with the model group, the expression levels of Notch1, PSD-95, SYN and BDNF increased in the electroacupuncture group (P < 0.01, P < 0.01, P < 0.05, P < 0.01), and the expression level of Hes1 decreased significantly (P < 0.05). Therefore, the mechanism by which electroacupuncture improves the learning and memory function of mice with radiation-induced brain injury may be related to the Notch signaling pathway and the increased expression of synaptic plasticity protein regulated by electroacupuncture.

Key words: electroacupuncture, radiation-induced brain injury, synaptic plasticity, Notch, signaling pathway, C57BL/6J mice, learning, memory