Long term impairment of cognitive functions and alterations of NMDAR subunits after continuous microwave exposure

Abstract Objective The long term effects of continuous microwave exposure cannot be ignored for the simulation of the real environment and increasing concerns about the negative cognitive effects of microwave exposure. Methods In this study, 220 male Wistar rats were exposed by a 2.856 GHz radiation source with the average power density of 0, 2.5, 5 and 10 mW/cm 2 for 6 min/day, 5 days/week and up to 6 weeks. The MWM task, the EEG analysis, the hippocampus structure observation and the western blot were applied until the 12 months after microwave exposure to detect the spatial learning and memory abilities, the cortical electrical activity, changes of hippocampal structure and the NMDAR subunits expressions. Results Results found that the rats in the 10 mW/cm 2 group showed the decline of spatial learning and memory abilities and EEG disorders (the decrease of EEG frequencies, and increase of EEG amplitudes and delta wave powers). Moreover, changes of basic structure and ultrastructure of hippocampus also found in the 10 and 5 mW/cm 2 groups. The decrease of NR 2A, 2B and p-NR2B might contribute to the impairment of cognitive functions. Conclusions Our findings suggested that the continuous microwave exposure could cause the dose-dependent long term impairment of spatial learning and memory, the abnormalities of EEG and the hippocampal structure injuries. The decrease of NMDAR key subunits and phosphorylation of NR 2B might contribute to the cognitive impairment.