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Leveque, P.

Publications and source records attributed to Leveque, P..

4 recordsLinked to original sources
bioRxiv2024

Repeated head-exposures to a 5G-3.5 GHz signal do not alter behavior but modify intracerebral gene expression in adult male mice.

The 5th generation (5G) of mobile communications promotes human exposures to electromagnetic fields exploiting the 3.5 GHz frequency band. We have analyzed behaviors, cognitive functions and gene expression in mice submitted to asymmetrical head-exposures to a 5G-modulated 3.5 GHz signal. The exposures were applied 1h daily, 5 days per week over a six-week period, at a specific absorption rate (SAR) averaging 0.19 W/kg over the brain. Locomotor activity in an open-field, object-place and object recognition memories were assessed repeatedly after four weeks of exposure and did not reveal any significant effect on the locomotion/exploration, anxiety level or memory processes. mRNA profiling was performed at the end of the exposure period in two symmetrical areas of the right and left cerebral cortex in which the SAR values were 0.43 and 0.14 W/kg, respectively. We found significant changes in the expression of less than 1% of the expressed genes with over-representations of genes related to glutamatergic synapses. The right cortical area differed from the left one by an over-representation of responsive genes encoded by the mitochondrial genome. Our data show that repeated head-exposures to a 5G-3.5 GHz signal can trigger mild transcriptome alterations without change in memory capacities or emotional state.

neuroscience↗
bioRxiv2024

Effects of head-only exposure to 900 MHz GSM electromagnetic fields in rats : changes in neuronal activity as revealed by c-Fos imaging without concomitant cognitive impairments

Over the last decade, animal models have been used to evaluate the physiological and cognitive effects of mobile phone exposures. Here, we used a head-only exposure system in rats to determine whether exposure to 900MHz GSM electromagnetic fields (EMF) induces regional changes in neuronal activation as revealed by c-Fos imaging. In a first study, rats were exposed for 2h to brain average specific absorption rates (BASARs) ranging from 0.5 to 6W/kg. Changes in neuronal activation were found to be dose-dependent with significant increases in c-Fos expression occurring at BASAR of 1W/kg in prelimbic, infralimbic, frontal and cingulate cortices. In a second study, animals were submitted to either a spatial working memory (WM) task in a radial maze or a spatial reference memory (RM) task in an open field arena. Exposures (45min) were conducted before each training session (BASARs of 1 and 3.5W/kg). Control groups included sham-exposed and control cage animals. In both tasks, behavioral performance evolved similarly in the four groups over testing days. However, c-Fos staining was significantly reduced in cortical areas (prelimbic, infralimbic, frontal, cingulate and visual cortices) and in hippocampus of animals engaged in the WM task (BASARs of 1 and 3.5W/kg). In the RM task, EMF exposure-induced decreases were limited to temporal and visual cortices (BASAR of 1W/kg). These results demonstrate that both acute and subchronic exposures to 900MHz EMFs can produce biological effects, but these effects were not sufficient to induce detectable cognitive deficits in the tasks used here.

neuroscience↗
bioRxiv2022

Comparative study between radiofrequency- and muscimol-induced inhibition of cultured networks of cortical neuron

Previous studies have shown that spontaneously active cultured networks of cortical neuron grown planar microelectrode arrays are sensitive to radiofrequency (RF) fields and exhibit an inhibitory response more pronounced as the exposure time and power increase. To better understand the mechanism behind the observed effects, we aimed at identifying similarities and differences between the inhibitory effect of RF fields (continuous wave, 1800 MHz) to the {gamma}-aminobutyric acid type A (GABAA) receptor agonist muscimol (MU). Inhibition of the network bursting activity in response to RF exposure became apparent at an SAR level of 28.6 W/kg and co-occurred with an elevation of the culture medium temperature of ~1 {degrees}C. Exposure to RF fields preferentially inhibits bursting over spiking activity and exerts fewer constraints on neural network bursting synchrony, differentiating it from a pharmacological inhibition with MU. Network rebound excitation, a phenomenon relying on the intrinsic properties of cortical neurons, was observed following the removal of tonic hyperpolarization after washout of MU but not in response to cessation of RF exposure. This implies that hyperpolarization is not the main driving force mediating the inhibitory effects of RF fields. At the level of single neurons, network inhibition induced by MU and RF fields occurred with reduced action potential (AP) half-width. As changes in AP waveform strongly influence efficacy of synaptic transmission, the narrowing effect on AP seen under RF exposure might contribute to reducing network bursting activity. By pointing only to a partial overlap between the inhibitory hallmarks of these two forms of inhibition, our data suggest that the inhibitory mechanisms of the action of RF fields differ from the ones mediated by the activation of GABAA receptors.

neuroscience↗