To investigate the effects of microwave radiation on associative learning and memory function and hippocampal structure of mice.

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/cm² 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.

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.

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.

Microwave radiation; Mouse; Hippocampus; Learning and memory; Tissue structure