Abstract: To investigate the effects of X-ray on the development of cerebellum and prefrontal cortex in mice during neonatal period, the mice in irradiation group were irradiated with whole-body X-ray dose of 2 Gy (2 Gy/min) at the postanal day 3(PD 3). Irradiated mice were euthanized at 7, 21 and 90 days after irradiation (PD 3+7, PD 3+21, PD 3+90) and brain samples were collected for different experimental studies. Hematoxylin-eosin (HE) was utilized to detect the pathomorphological changes of brain tissue; Immunohisto-chemistry were used to detect the protein expression of IBa1 and GFAP; Western blotting were used to detect the protein expression of IL-1β and TNF-α. In the irradiation group, the inflammatory cell infiltration was observed in the cerebellum and prefrontal cortex, and the thickness of external granular layer (EGL) narrowed. Purkinje cells migrated to internal granular layer (IGL) and some cells were lost in the cerebellum. Compared with the control group, the number of IBa1 positive cells increased at 21 days after irradiation (p<0.05), while the number of GFAP positive cells decreased at 7 days after irradiation in cerebellum (p<0.05). The number of IBa1 positive cells continued to increase until adulthood (p<0.05, p<0.01), and the number of GFAP positive cells continued to decrease until adulthood in prefrontal cortex (p<0.01). The protein expression of IL-1β increased at 90 days after radiation in cerebellum and prefrontal cortex (p<0.05), while the expression of TNF-α did not change. Neonatal exposure to 2 Gy X-ray caused continuous pathological changes in the granulosa cell layer, molecular layer and Purkinje cell layer of cerebellum, and inflammatory cell aggregation in the prefrontal cortex. Neonatal exposure to 2 Gy X-ray increased the number of microglia in the prefrontal cortex and cerebellum, decreased the number of astrocytes. IL-1β is mainly the inflammatory factor.

Key words: ionizing radiation, cerebellum, prefrontal cortex, glioblastoma, neuroinflammation