RESUMO
Objective:To investigate the effects of microwave radiation on associative learning and memory function and hippocampal structure of mice.Methods:C57BL/6N mice were ramdomly divided into sham-radiated group ( n=27) and radiation group ( n=2). The radiation group was exposed to microwave at 2.856 GHz, 8 mW/cm 2 for 15 min, then their spatial and associative learning and memory function were examined with the morris water maze and shuttle box behavior experiment. The pathological changes of hippocampal tissue were observed by HE staining and light microscope, the ultrastructural changes of hippocampal tissue were observed by transmission electron microscope. Results:After microwave radiation, the times of mice crossing the platform for the reverse space exploration decreased from(3.60±0.79) times to (2.55±0.47) times( t=2.21, P=0.046), the average active escape rate decreased significantly ( t = 2.70, P<0.05), and the average active latency and the total shock time was significantly prolonged ( t = -3.09, -3.02, P < 0.05). At 8 d after microwave radiation, the nuclei of some neurons in the CA3 and DG regions of the hippocampus were pyknosis. The neurons were apoptotic, the synaptic spaces blurred, the glial cells swollen, and the perivascular spaces widened in the CA3 region of the hippocampus. Conclusions:Microwave radiation can decline the spatial reference memory ability and associative learning and memory ability of mice. The morphological and pathological changes of hippocampus are the structural basis of this dysfunction.
RESUMO
In this study, fifty-four male Wistar rats were randomly divided into four groups according to the static magnetic field (SMF) intensity, namely, control, low-intensity, moderate-intensity, and high-intensity groups. The rats' whole body was exposed to a superconducting magnet exposure source. The exposure SMF intensity for the low-intensity, moderate-intensity, and high-intensity groups was 50 m T, 100 m T, and 200 m T, respectively, and the exposure time was 1 h/day for consecutive 15 days. After different exposure times, glucose metabolism in rats' brain was evaluated by micro-positron emission tomography (micro-PET), and the expression of hexokinase 1(HK1) and 6-phosphate fructokinase-1(PFK1) was detected by western blot. The exploration and locomotion abilities of the rats were evaluated by conducting open field test (OFT). Furthermore, pathological changes of rats' brain were observed under a microscope by using hematoxylin-eosin staining. PET results showed that moderate-intensity SMFs could cause fluctuant changes in glucose metabolism in rats' brain and the abnormalities were SMF intensity dependent. The expression of the two rate-limiting enzymes HK1 and PFK1 in glucose metabolism in brain significantly decreased after SMF exposure. The OFT showed that the total distance, surrounding distance, activity time, and climbing and standing times significantly decreased after SMF exposure. The main pathological changes in the brain were pyknosis, edema of neurons, and slight widening of the perivascular space, which occurred after 15 times of exposure. This study indicated that SMF exposure could lead to abnormal glucose metabolism in the brain and might result in anxiety-like behaviors.
