Chronic intermittent hypobaric hypoxia improved the memory and cognitive impairment of mice with whole brain irradiation / 中华放射医学与防护杂志

ABSTRACT

Objective:To observe the changes in hippocampus (CA1) and study the effect of chronic intermittent hypobaric hypoxia (CIHH) preconditioning on the memory and cognitive function of mice exposed to the whole brain irradiation.Methods:A total of 48 C57BL/6 male mice were randomly divided into control group, CIHH group, irradiation group (IR group) and CIHH+ IR group. For IR group, the whole brain of mice were irradiated with 10 Gy of 6 MV X-rays in a single fraction. Pretreatment with CIHH was performed by placing mice in a hypobaric chamber before radiation. The mirrors water maze experiment was performed in the four groups to observe the escape latency, the number of crossing platforms and the target quadrant residence time. Nissl staining was used to observe the changes of neuronal cells in hippocampal CA1 region. Immunofluorescence was used to detect the expression of microtubule-associated protein cells (DCX) in the subgranular zone (SGZ) of hippocampal dentate gyrus (DG) to evaluate neurogenesis.Results:After 30 days of whole brain irradiation, the escape latency of mice prolonged gradually, the frequency of crossing platform decreased ( P< 0.001), and the exploration time in the target quadrant decreased ( P<0.001). X-ray irradiation caused disorder of mice neuronal cells, degeneration and necrosis of neuronal cells, and decrease of DCX expression in CA1 region of mice. Compared with IR group, the CIHH+ IR group had shortened the escape latency, increased the frequency of crossing platform [(2.08±0.26) vs. (0.83±0.24), P<0.001], and also increased the exploration time in the target quadrant [(14.12±0.82)s vs. (7.42±0.73)s, P<0.001]. Pretreatment with CIHH also alleviated the deformation and necrosis of neurons in hippocampus, and increased DCX expression in CA1 region. Conclusions:Pretreatment of mice with CIHH plays a protective role in radiation induced hippocampal injury.