Decreased spontaneous electrical activity in neuronal networks exposed to radiofrequency 1,800 MHz signals

Abstract

So far, the only identified biological effects of radiofrequency fields (RF) are known to be caused by heating but the issue of potential nonthermal biological effects, especially on the central nervous system (CNS), remains open. We previously reported a decrease in the firing and bursting rates of neuronal cultures exposed to a Global System for Mobile (GSM) RF field at 1800 MHz for 3 min (Moretti et al. 2013). The aim of the present work was to assess the dose-response relationship for this effect, and also identify a potential differential response elicited by pulse-modulated GSM and continuous-wave (CW) RF fields. Spontaneous bursting activity of neuronal cultures from rat embryonic cortices was recorded using 60-electrode Multi Electrode Arrays (MEAs). At 17-28 days in vitro, the neuronal cultures were subjected to 15-min RF exposures, at SARs (Specific Absorption Rates) ranging from 0.01 to 9.2 W/kg. Both GSM and CW signals elicited a clear decrease in bursting rate during the RF exposure phase. This effect became more marked with increasing SAR and lasted even beyond the end of exposure for the highest SAR levels. Moreover, the amplitude of the effect was greater with the GSM signal. Altogether, our experimental findings provide evidence for dose-dependent effects of RF signals on the bursting rate of neuronal cultures and suggest that part of the mechanism is nonthermal.

1800 MHz Radiofrequency Electromagnetic Field Impairs Neurite Outgrowth Through Inhibiting EPHA5 Signaling

“…Besides, it has been revealed that RF-EMF exposure causes neural behavior changes in rats and mice, such as influenced emotional behavior, decreased locomotor activities, and impairment of cognitive functions (Zhang et al, 2017;Kim et al, 2019b). RF-EMF exposure also influenced the electrical activity in neuronal networks in the brain and peripheral neurons (El Khoueiry et al, 2018;Prucha et al, 2018). Recently, it has been found that prenatal RF-EMF exposure inhibits the proliferation and differentiation of embryonic neural stem cells (NSCs), which affects the neurological functions of adults (Kaplan et al, 2016;Eghlidospour et al, 2017).…”

A Novel Microwave Treatment for Sleep Disorders and Classification of Sleep Stages Using Multi-Scale Entropy

“…These results indicate that the scattering of microwave in the brain functional sites leads to the polarization and depolarization of the brain tissue cell fluid, resulting in the change in dielectric constant and conductivity, which in turn changes the characteristics of microwave scattering to achieve the purpose of imaging [ 19 ]. Some recent reports have addressed the fact that microwave scattering has a significant effect on resting state EEG, particularly on the fact that the power of the EEG increases in the alpha band [ 24 , 25 ]. Exposure to electromagnetic fields can cause changes in the sleep EEG power [ 26 ], thereby suggesting that electromagnetic waves may affect brain function and the recovery process involved in sleep.…”

Changes in the Excitability of Primary Hippocampal Neurons Following Exposure to 3.0 GHz Radiofrequency Electromagnetic Fields

“…Conversely, other studies, like those mentioned above, have reported the effects with small temperature increase as non-thermal. For example, in the case of a decrease in spontaneous electrical activity in cultured cortical neurons during a short exposure to GSM 1800 MHz (15 min at SAR ranging from 0.01 to 9.2 W/kg), the authors also examined the in uence of bulk heating in the culture medium, and found that it caused increased burst activity 23 . Notably, the results showed an opposite effect with bulk heating versus RF-EMF exposure since RF-EMF resulted in decreased burst activity 23 .…”

“…For example, in the case of a decrease in spontaneous electrical activity in cultured cortical neurons during a short exposure to GSM 1800 MHz (15 min at SAR ranging from 0.01 to 9.2 W/kg), the authors also examined the in uence of bulk heating in the culture medium, and found that it caused increased burst activity 23 . Notably, the results showed an opposite effect with bulk heating versus RF-EMF exposure since RF-EMF resulted in decreased burst activity 23 . In this experiment, the authors imitated the 0.7 °C temperature rise modeled for RF-EMF exposure (SAR of 9.2 W/kg) by subjecting the cortical neuronal cultures to 15-min heating in the incubator using a heat produced by an electric hotplate.…”

“…El Khoueiry et al reported a dose-dependent decrease in neurons electrical activity during 15-min exposures to 1,800 MHz RF-EMF signals. Using 60-electrode multielectrode arrays (MEAs), the group measured a dose-dependent decrease in spontaneous bursting rates in cultured cortical neurons during both pulse-modulated Global System for Mobile Communication (GSM) and continuous wave (CW) RF-EMF exposures at SAR ranging from 0.01 to 9.2 W/kg 23 . Moreover, Xu et al showed a decrease in excitability of cultured hippocampal neurons demonstrated by a reduction in the amplitude of a-amino-3-hydroxy-5-methyl-4-soxazole propionic acid (AMPA) miniature excitatory postsynaptic currents (mEPSCs) following a chronic exposure to 1800 MHz GSM at an average SAR of 2.4 W/kg for 15 min per day for 8 days 24 .…”