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Li, C., Xie, M., Luo, F., He, C., Wang, J., Tan, G., et al. (2014). The extremely low-frequency magnetic field exposure differently affects the AMPAR and NMDAR subunit expressions in the hippocampus, entorhinal cortex and prefrontal cortex without effects on the rat spatial learning and memory. Environ Res, 134, 74–80.
Abstract: In the present study, we investigated the effects of chronic exposure (14 and 28 days) to a 50 Hz, 0.5 mT extremely low-frequency magnetic field (ELF-MF) on the NMDAR and AMPAR subunit expressions and rat spatial learning and memory. Using the Western blotting method, we found ELF-MF exposure specifically decreased the expressions of GluA2 in the EC post 28 day exposure and GluA3 of AMPAR subunits in the PFC after 14 day exposure, while it did not affect the AMPAR subunit expression in the hippocampus at both time points. As for NMDAR subunits, 14 day ELF-MF exposure significantly increased the levels of GluN2A and GluN2B in the hippocampus. Moreover, the levels of GluN1 and GluN2A were enhanced in the EC and PFC after two weeks of ELF-MF exposure. Interestingly, 28 day ELF-MF exposure induced a different expression pattern for NMDAR subunits. The increased GluN2A expression observed at 14 day post ELF-MF exposure was recovered after prolonged exposure in the hippocampus and PFC. In the EC, the increased expression of GluN1 achieved to control level and, specifically, a decrease in GluN2A level was observed. Surprisingly, neither 14 nor 28 day ELF-MF did affect the rat spatial reference memory as assessed by water maze. These results indicate that the dynamic and brain-region specific changes in ionotropic glutamate receptor expression induced by ELF-MF are insufficient to influence the rat spatial learning ability.
Keywords: Animals; Entorhinal Cortex/*metabolism; Hippocampus/*metabolism; *Magnetic Fields; Male; Memory; Prefrontal Cortex/*metabolism; Rats; Rats, Sprague-Dawley; Receptors, AMPA/*metabolism; Receptors, N-Methyl-D-Aspartate/*metabolism; Spatial Learning; AMPARs; Entorhinal cortex; Extremely low frequency magnetic field; Learning and memory; NMDARs
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Li, Y., Liu, X., Liu, K., Miao, W., Zhou, C., Li, Y., et al. (2014). Extremely Low-Frequency Magnetic Fields Induce Developmental Toxicity and Apoptosis in Zebrafish (Danio rerio) Embryos. Biological Trace Element Research, 162, 324–332.
Keywords: apoptosis; developmental; elf-mf; toxicity; zebrafish embryo
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Li, Y., Yan, X., Liu, J., Li, L., Hu, X., Sun, H., et al. (2014). Pulsed electromagnetic field enhances brain-derived neurotrophic factor expression through L-type voltage-gated calcium channel- and Erk-dependent signaling pathways in neonatal rat dorsal root ganglion neurons. Neurochemistry International, 75, 96–104.
Keywords: electromagnetic field
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Li, Y., Zhang, C., & Song, T. (2014). Disturbance of the magnetic field did not affect spatial memory. Physiol Res, 63(3), 377–385.
Abstract: Extremely low-frequency magnetic field (ELF-MF) has been suggested to influence the cognitive capability but this should be dynamically evaluated in a longitudinal study. Previous training can affect performance, but the influence under magnetic field is unclear. This study aims to evaluate the effects of previous training and ELF-MF exposure on learning and memory using the Morris water maze (MWM). Sprague-Dawley rats were subjected to MWM training, ELF-MF exposure (50 Hz, 100 microT), or ELF-MF exposure combined with MWM training for 90 days. Normal rats were used as controls. The MWM was used to test. The data show that the rats exposed to training and ELF-MF with training performed better on spatial acquisition when re-tested. However, during the probe trial the rats showed no change between the training phase and the test phase. Compared with the control group, the ELF-MF group showed no significant differences. These results confirm that previous training can improve the learning and memory capabilities regarding spatial acquisition in the MWM and this effect can last for at least 90 days. However, this improvement in learning and memory capabilities was not observed during the probe trial. Furthermore, ELF-MF exposure did not interfere with the improvement in learning and memory capabilities.
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Liorni, I., Parazzini, M., Fiocchi, S., Douglas, M., Capstick, M., Gosselin, M. - C., et al. (2014). Dosimetric study of fetal exposure to uniform magnetic fields at 50 Hz. Bioelectromagnetics, 35(8), 580–597.
Abstract: In this paper, fetal exposure to uniform magnetic fields (MF) with different polarizations is quantified at 50 Hz. Numerical computations were performed on high-resolution pregnant models at 3, 7, and 9 months of gestational age (GA), that distinguish a high number of fetal tissues. Fetal whole-body and tissue-specific induced electric fields (E) and current densities (J) were analyzed as a function of both the extremely low frequency magnetic field (ELF-MF) polarization and GA. Additionally, the induced field variation due to changes in fetal position was analyzed by means of two new pregnant models. The uncertainty budget due to the grid resolution was also calculated. Finally, the compliance of the fetal exposure to the ICNIRP Guidelines was checked. A fetal exposure matrix was built at 50 Hz, which could be used to further investigate possible interaction mechanisms between ELF-MF and the associated health risk. Some specific findings were: (1) the induced fields increased with GA; (2) the maxima E were found in skin and fat tissues at each GA; (3) fetal tissue-specific exposure was modified as a function of GA and polarization; (4) the change of the fetal position in the womb significantly modified the induced E in some fetal tissues; (5) the induced fields were in compliance with ICNIRP Guidelines and the results were quite below the permitted threshold limit.
Keywords: ELF magnetic fields; numerical dosimetry; pregnant woman exposure
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