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.
Purpose: The present study was conducted to re-evaluate the effect of low-level 1800 MHz RF signals (up to public exposure level for local exposure) on RAS/MAPK activation in live cells. Material and methods: Using molecular probes based on the Bioluminescence Resonance Energy Transfer technique (BRET), we assessed the effect of Continuous wave (CW) and Global System for Mobile (GSM)-modulated 1800 MHz signals (up to 2 W/kg) on ERK and RAS kinases' activity in live HuH7 cells. Results: We found that radiofrequency field (RF) exposure for 24h altered neither basal level of RAS and ERK activation nor the potency of phorbol-12-myristate-13-acetate (PMA) to activate RAS and ERK kinases, whatever the Specific Absorption Rate (SAR) or signal used. However, we found that exposure to GSM-modulated 1800 MHz signals at 2 W/kg decreased the PMA maximal efficacy to activate both RAS and ERK kinases' activity. Exposure with CW 1800 MHz signal at 2 W/kg only decreased maximal efficacy of PMA to activate ERK but not RAS. No effects of RF exposure at 0.5 W/kg was observed on maximal efficacy of PMA to activate either RAS or ERK whatever the signal used.
Conclusion:Our results indicate that RF exposure decreases the efficiency of the cascade of events, which, from the binding of PMA to its receptor(s), leads to the activation of RAS and ERK kinases. This effect of RF exposure is reminiscent of RF-induced adaptive response.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.