Transcriptional response of primary hippocampal neurons following exposure to 3.0 GHz radiofrequency electromagnetic fields

Exposure to radiofrequency (RF) electromagnetic fields (EMF) has been associated with the modulation of neuronal electrophysiology and synaptic plasticity. Given the potential of these changes to coincide with alterations in gene expression, this study investigated whether a transcriptional response would occur in neurons following exposure to RF-EMF, under both thermal and nonthermal conditions. Rat primary hippocampal neurons (PHNs) underwent either a single (one-time) or a multiple (3-times, once a day) exposures to RF-EMF (3.0 GHz, CW) at two different mean specific absorption rate (SAR) values of 0.57 W/kg or 5.91 W/kg, which induced a temperature change (Delta T degrees C) of approximately 0.3 degrees C or 3.6 degrees C, respectively. Alteration in transcription in the RF-EMF-exposed PHNs versus the sham counterparts was assessed at 0, 4, and 24 h postexposure via high-throughput RNA sequencing using Illumina HiSeq. 2000. A total of 20 differentially expressed genes (DEGs) exhibited significant upregulation due to RF-EMF exposure, observed only with the high SAR dose that induced a thermal rise. However, the expression of these DEGs was not significant at 24 h postexposure. Our findings confirmed a lack of nonthermal effects on gene expression under low RF-EMF exposure conditions as evaluated. Additionally, the results indicated a slight thermal effect of exposures at the dose nearing the standards threshold of 4 W/kg; however, the effect appeared to be transient. The study suggests that RF-EMF exposures at a level close to the standards threshold, despite inducing mild temperature elevations (i.e., 3-5 degrees C above normal), would not trigger biologically critical cellular changes. An investigation of the effect of single and multiple exposure to 3.0 GHz radiofrequency electromagnetic fields (RF-EMF) at low and high doses (i.e., mean SAR values of 0.57 and 5.91 W/kg, respectively) on gene transcription in primary hippocampal neurons is presented. Significant change in a subset of genes was observed following RF-EMF exposure to the higher dose, which also resulted in a temperature rise in the media up to 3.6 +/- 0.6 degrees C. The expression level was shown to revert to baseline at 24 h postexposure, suggesting no significant biological impact on cells at the evaluated RF-EMF conditions.