Zhu R, Wang H, Xu X, et al. Effects of 1.5 and 4.3 GHz microwave radiation on cognitive function and hippocampal tissue structure in Wistar rats. Sci Rep. 2021;11(1):10061. Published 2021 May 12. doi:10.1038/s41598-021-89348-4
Previous studies have shown that single-frequency microwave radiation can lead to cognitive decline in rats. However, few studies have focused on the combined effects of irradiation with different frequencies of microwaves. Our research aimed to investigate the effects of 1.5 GHz and 4.3 GHz microwave radiation, singly and in combination, on cognitive function and hippocampal tissue structure in rats. A total of 140 male Wistar rats were randomly divided into 4 groups: the S group (sham radiation group), L10 group (10 mW/cm2 1.5 GHz group), C10 group (10 mW/cm2 4.3 GHz band group) and LC10 group (10 mW/cm2 1.5 and 4.3 GHz multi-frequency radiation group). For 1–28 days after microwave radiation, we analyzed the average escape latency for the Morris water maze task, electroencephalograms, change in hippocampal tissue structure and ultrastructure, content of the Nissl body in the hippocampus, and activities of lactate dehydrogenase and succinate dehydrogenase. Compared to the S group, all exposure groups showed varying degrees of learning and memory decline and hippocampal structural damage. The results showed that 1.5 GHz and 4.3 GHz microwave radiation was able to induce cognitive impairment and hippocampal tissue damage in rats and combined radiation with both frequencies caused more serious injuries, but none of these damaging effects varied with microwave frequency.
Therefore, we concluded that microwave exposure was able to affect spatial learning and memory abilities, as well as the structure and energy metabolism of the hippocampus. However, the damage effect of microwave on hippocampus might be reversible, as at 28 days after the radiation, for rats in each radiation group, the AEL, EEG, hippocampus microstructures, and the content of hippocampus Nissl body were restored to similar conditions as those in the sham group. Meanwhile there were no significant differences between the 1.5-GHz and 4.3-GHz microwave exposure groups, and no interaction effects were observed. Even so, we have also observed that the damage effects caused by microwaves at the two frequencies are slightly different. This may be due to the difference in parameters such as frequency and wavelength, and the specifics still need to be further studied. Our research could provide evidence for the subsequent construction of a microwave damage model and the study of the microwave damage mechanism.