Effects of fetal microwave radiation exposure on offspring behavior in mice

Abstract

The recent rapid development of electronic communication techniques is resulting in a marked increase in exposure of humans to electromagnetic fields (EMFs). This has raised public concerns about the health hazards of long-term environmental EMF exposure for fetuses and children. Some studies have suggested EMF exposure in children could induce nervous system disorders. However, gender-dependent effects of microwave radiation exposure on cognitive dysfunction have not previously been reported. Here we investigated whether in utero exposure to 9.417-GHz microwave throughout gestation (Days 3.5-18) affected behavior, using the open field test (OFT), elevated-plus maze (EPM), tail suspension test (TST), forced swimming test (FST) and Morris water maze (MWM). We found that mice showed less movement in the center of an open field (using the OFT) and in an open arm (using the EPM) after in utero exposure to 9.417-GHz radiation, which suggested that the mice had increased anxiety-related behavior. Mice demonstrated reduced immobility in TST and FST after in utero exposure to 9.417-GHz radiation, which suggested that the mice had decreased depression-related behavior. From the MWM test, we observed that male offspring demonstrated decreased learning and memory, while females were not affected in learning and memory, which suggested that microwaves had gender-dependent effects. In summary, we have provided the first experimental evidence of microwaves inducing gender-dependent effects.

Keywords: anxiety; depression; gender-specific; learning and memory; microwave radiation.

Fig. 1.

The effect of fetal microwave exposure on anxiety as evaluated by the OFT. The total distance moved by offspring among the study groups was no different (A). However, the frequency and duration of entry into the center zone of the exposed mice was lower than that of the Control and Sham-control mice (B, C), indicating anxiety behavior. Data are means ± SEM, 12 animals per group; *P < 0.05, versus corresponding values in Control and Sham-control groups.

Fig. 2.

The effect of fetal microwave exposure on anxiety as determined using EPM. Compared with the Control and Sham-control mice, the offspring of exposed mice had a lower percent open arm frequency (A) and percent open arm time (B), suggesting anxiety-related behavior, in accordance with the OFT. Data are means ± SEM, 12 animals per group; **P < 0.01, vs corresponding values in Control and Sham-control groups.

Fig. 3.

The effect of fetal microwave exposure on depression based on the TST and FST. Radiation exposure decreased the immobility time compared with the Control and Sham-control mice in TST (A) and FST (B), illustrating the decreased depression-related behavior. Data are means ± SEM, 12 animals per group; **P < 0.01, versus corresponding values in Control and Sham-Control groups.

Fig. 4.

The effect of fetal microwave exposure on learning and memory assessed using the MWM. All mice showed a progressive decline in escape latency during the five training days. Microwave exposure induced significant prolongation in latency time on the fourth and fifth days for male offspring mice (A), while there was no difference for the female offspring mice (B). In the probe test, the time spent in the quadrant of the original platform location, and the frequency with which animals crossed the original platform location for male mice in the Radiation group was significantly reduced compared with the Control and Sham-control groups (C), whereas the females did not differ among the groups (D), suggesting impairment in learning and memory for male mice, but no effect in the female. Data are means ± SEM, eight animals per group, *P < 0.05, **P < 0.01, vs corresponding values in the Control group, ^#P < 0.05 vs corresponding values in Sham-control group.