RESUMEN
Whether ion channels experience ligand-dependent dynamic ion selectivity remains of critical importance since this could support ion channel functional bias. Tracking selective ion permeability through ion channels, however, remains challenging even with patch-clamp electrophysiology. In this study, we have developed highly sensitive bioluminescence resonance energy transfer (BRET) probes providing dynamic measurements of Ca2+ and K+ concentrations and ionic strength in the nanoenvironment of Transient Receptor Potential Vanilloid-1 Channel (TRPV1) and P2X channel pores in real time and in live cells during drug challenges. Our results indicate that AMG517, BCTC, and AMG21629, three well-known TRPV1 inhibitors, more potently inhibit the capsaicin (CAPS)-induced Ca2+ influx than the CAPS-induced K+ efflux through TRPV1. Even more strikingly, we found that AMG517, when injected alone, is a partial agonist of the K+ efflux through TRPV1 and triggers TRPV1-dependent cell membrane hyperpolarization. In a further effort to exemplify ligand bias in other families of cationic channels, using the same BRET-based strategy, we also detected concentration- and time-dependent ligand biases in P2X7 and P2X5 cationic selectivity when activated by benzoyl-adenosine triphosphate (Bz-ATP). These custom-engineered BRET-based probes now open up avenues for adding value to ion-channel drug discovery platforms by taking ligand bias into account.
Asunto(s)
Canales de Potencial de Receptor Transitorio , Canales de Potencial de Receptor Transitorio/metabolismo , Canales Catiónicos TRPV/metabolismo , Ligandos , Capsaicina/farmacología , Transferencia de Energía , SesgoRESUMEN
Whether human cells are impacted by environmental electromagnetic fields (EMF) is still a matter of debate. With the deployment of the fifth generation (5G) of mobile communication technologies, the carrier frequency is increasing and the human skin becomes the main biological target. Here, we evaluated the impact of 5G-modulated 3.5 GHz radiofrequency (RF) EMF on mitochondrial stress in human fibroblasts and keratinocytes that were exposed for 24 h at specific absorption rate of 0.25, 1, and 4 W/kg. We assessed cell viability, mitochondrial reactive oxygen species (ROS) production, and membrane polarization. Knowing that human skin is the main target of environmental ultraviolet (UV), using the same read-out, we investigated whether subsequent exposure to 5G signal could alter the capacity of UV-B to damage skin cells. We found a statistically significant reduction in mitochondrial ROS concentration in fibroblasts exposed to 5G signal at 1 W/kg. On the contrary, the RF exposure slightly but statistically significantly enhanced the effects of UV-B radiation specifically in keratinocytes at 0.25 and 1 W/kg. No effect was found on mitochondrial membrane potential or apoptosis in any cell types or exposure conditions suggesting that the type and amplitude of the observed effects are very punctual.
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Piel , Rayos Ultravioleta , Humanos , Especies Reactivas de Oxígeno/metabolismo , Rayos Ultravioleta/efectos adversos , Piel/metabolismo , Ondas de Radio/efectos adversos , Queratinocitos/metabolismo , Campos ElectromagnéticosRESUMEN
This study aims to analyze in real-time the potential modifications induced by low-level continuous-wave and Global System for Mobile Communications radiofrequency (RF) exposure at 1.8 GHz on brain activation in anesthetized mice. A specific in vivo experimental setup consisting of a dipole antenna for the local exposure of the brain was fully characterized. A unique neuroimaging technique based on a functional ultrasound (fUS) probe was used to observe the areas of mice brain activation simultaneously to the RF exposure with unprecedented spatial and temporal resolution (~100 µm, 1 ms) following manual whisker stimulation using a brush. Numerical and experimental dosimetry was carried out to characterize the exposure and to guarantee the validity of the biological results. Our results show that the fUS probe can be efficiently used during in vivo exposure without interference with the dipole. In addition, we conclude that exposure to brain-averaged specific absorption rate levels of 2 and 6 W/kg does not introduce significant changes in the time course of the evoked fUS response in the left barrel field cortex. The proposed technique represents a valuable instrument for providing new insights into the possible effects induced on brain activation under RF exposure. For the first time, brain activity under mobile phone exposure was evaluated in vivo with fUS imaging, paving the way for more realistic exposure configurations, i.e. awake mice and new signals such as the 5 G networks. © 2022 Bioelectromagnetics Society.
Asunto(s)
Teléfono Celular , Ondas de Radio , Animales , Encéfalo/diagnóstico por imagen , Ratones , RadiometríaRESUMEN
It remains controversial whether exposure to environmental radiofrequency signals (RF) impacts cell status or response to cellular stress such as apoptosis or autophagy. We used two label-free techniques, cellular impedancemetry and Digital Holographic Microscopy (DHM), to assess the overall cellular response during RF exposure alone, or during co-exposure to RF and chemical treatments known to induce either apoptosis or autophagy. Two human cell lines (SH-SY5Y and HCT116) and two cultures of primary rat cortex cells (astrocytes and co-culture of neurons and glial cells) were exposed to RF using an 1800 MHz carrier wave modulated with various environmental signals (GSM: Global System for Mobile Communications, 2G signal), UMTS (Universal Mobile Telecommunications System, 3G signal), LTE (Long-Term Evolution, 4G signal, and Wi-Fi) or unmodulated RF (continuous wave, CW). The specific absorption rates (S.A.R.) used were 1.5 and 6 W/kg during DHM experiments and ranged from 5 to 24 W/kg during the recording of cellular impedance. Cells were continuously exposed for three to five consecutive days while the temporal phenotypic signature of cells behavior was recorded at constant temperature. Statistical analysis of the results does not indicate that RF-EMF exposure impacted the global behavior of healthy, apoptotic, or autophagic cells, even at S.A.R. levels higher than the guidelines, provided that the temperature was kept constant.
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Apoptosis , Autofagia , Ondas de Radio , Coloración y Etiquetado , Trióxido de Arsénico/farmacología , Astrocitos/efectos de los fármacos , Astrocitos/patología , Autofagia/efectos de los fármacos , Línea Celular Tumoral , Medio de Cultivo Libre de Suero , Impedancia Eléctrica , Holografía , Humanos , Neuronas/efectos de los fármacos , Neuronas/patología , Factores de TiempoRESUMEN
Ion channels are attractive drug targets for many therapeutic applications. However, high-throughput screening (HTS) of drug candidates is difficult and remains very expensive. We thus assessed the suitability of the bioluminescence resonance energy transfer (BRET) technique as a new HTS method for ion-channel studies by taking advantage of our recently characterized intra- and intermolecular BRET probes targeting the transient receptor potential vanilloid type 1 (TRPV1) ion channel. These BRET probes monitor conformational changes during TRPV1 gating and subsequent coupling with calmodulin, two molecular events that are intractable using reference techniques such as automated calcium assay (ACA) and automated patch-clamp (APC). We screened the small-sized Prestwick chemical library, encompassing 1200 compounds with high structural diversity, using either intra- and intermolecular BRET probes or ACA. Secondary screening of the detected hits was done using APC. Multiparametric analysis of our results shed light on the capability of calmodulin inhibitors included in the Prestwick library to inhibit TRPV1 activation by capsaicin. BRET was the lead technique for this identification process. Finally, we present data exemplifying the use of intramolecular BRET probes to study other transient receptor potential (TRP) channels and non-TRPs ion channels. Knowing the ease of use of BRET biosensors and the low cost of the BRET technique, these assays may advantageously be included for extending ion-channel drug screening. SIGNIFICANCE STATEMENT: This study screened a chemical library against TRPV1 ion channel using bioluminescence resonance energy transfer (BRET) molecular probes and compared the results with the ones obtained using reference techniques such as automated calcium assay and automated patch-clamp. Multiparametric analysis of our results shed light on the capability of calmodulin antagonists to inhibit chemical activation of TRPV1 and indicates that BRET probes may advantageously be included in ion channel drug screening campaigns.
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Transferencia de Energía por Resonancia de Bioluminiscencia/métodos , Descubrimiento de Drogas/métodos , Evaluación Preclínica de Medicamentos/métodos , Ensayos Analíticos de Alto Rendimiento/métodos , Canales Catiónicos TRPV/metabolismo , Bioensayo/métodos , Calcio/química , Calmodulina/antagonistas & inhibidores , Células HEK293 , Humanos , Ligandos , Potenciales de la Membrana/efectos de los fármacos , Técnicas de Placa-Clamp , Bibliotecas de Moléculas Pequeñas , Canales Catiónicos TRPV/agonistas , Canales Catiónicos TRPV/antagonistas & inhibidoresRESUMEN
The rapid development of wireless communications has raised questions about their potential health risks. 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 1,800 MHz for 3 min (Moretti D, Garenne A, Haro E, Poulleier de Gannes F, Lagroye I, Lévêque P, Veyret B, Lewis N. Bioelectromagnetics 34: 571-578, 2013). The aim of the present work was to assess the dose-response relationship for this effect and also to 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 multielectrode arrays (MEAs). At 17-28 days in vitro, the neuronal cultures were subjected to 15-min RF exposures, at specific absorption rates (SAR) 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. NEW & NOTEWORTHY In this study, we investigated the effects of some radiofrequency (RF) exposure parameters on the electrical activity of neuronal cultures. We detected a clear decrease in bursting activity, dependent on exposure duration. The amplitude of this effect increased with the specific absorption rate (SAR) level and was greater with Global System for Mobile signal than with continuous-wave signal, at the same average SAR. Our experiment provides unique evidence of a decrease in electrical activity of cortical neuronal cultures during RF exposure.
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Potenciales de Acción/efectos de la radiación , Neuronas/efectos de la radiación , Ondas de Radio , Animales , Células Cultivadas , Neuronas/fisiología , Ratas , Ratas Sprague-DawleyRESUMEN
Multiplexed bioluminescence resonance energy transfer (BRET) assays were developed to monitor the activation of several functional transient receptor potential (TRP) channels in live cells and in real time. We probed both TRPV1 intramolecular rearrangements and its interaction with Calmodulin (CaM) under activation by chemical agonists and temperature. Our BRET study also confirmed that: (1) capsaicin and heat promoted distinct transitions, independently coupled to channel gating, and that (2) TRPV1 and Ca2+-bound CaM but not Ca2+-free CaM were preassociated in resting live cells, while capsaicin activation induced both the formation of more TRPV1/CaM complexes and conformational changes. The BRET assay, based on the interaction with Calmodulin, was successfully extended to TRPV3 and TRPV4 channels. We therefore developed a full-spectral three-color BRET assay for analyzing the specific activation of each of the three TRPV channels in a single sample. Such key improvement in BRET measurement paves the way for the simultaneous monitoring of independent biological pathways in live cells.
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Transferencia de Energía , Mediciones Luminiscentes , Canales Catiónicos TRPV/química , Canales Catiónicos TRPV/metabolismo , Técnicas Biosensibles , Calmodulina/metabolismo , Células HEK293 , Calor , HumanosRESUMEN
The present study focused on gap junctional intercellular communication (GJIC) as a target for biological effects of extremely low-frequency (ELF) magnetic field (MF) exposure. Fluorescence recovery after photobleaching microscopy (FRAP) was used to visualize diffusion of a fluorescent dye between NIH3T3 fibroblasts through gap junctions. The direct effect of 24 h exposure to 50 Hz MF at 0.4 or 1 mT on GJIC function was assessed in one series of experiments. The potential synergism of MF with an inhibitor of GJIC, phorbol ester (TPA), was studied in another series by observing FRAP when NIH3T3 cells were incubated with TPA for 1 h following 24 h exposure to MF. In contrast to other reports of ELF-MF effects on GJIC, under our experimental conditions we observed neither direct inhibition of GJIC nor synergism with TPA-induced inhibition from 50 Hz MF exposures.
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Comunicación Celular , Uniones Comunicantes , Campos Magnéticos , Animales , Colorantes Fluorescentes/metabolismo , Cinética , Ratones , Células 3T3 NIHRESUMEN
We estimate that there are about 100,000 workers from different disciplines, such as radiographers, nurses, anesthetists, technicians, engineers, etc., who can be exposed to substantial electromagnetic fields (compared to normal background levels) around magnetic resonance imaging (MRI) scanners. There is a need for well-designed epidemiological studies of MRI workers but since the exposure from MRI equipment is a very complex mixture of static magnetic fields, switched gradient magnetic fields, and radiofrequency electromagnetic fields (RF EMF), it is necessary to discuss how to assess the exposure in epidemiological studies. As an alternative to the use of job title as a proxy of exposure, we propose an exposure categorization for the different professions working with MRI equipment. Specifically, we propose defining exposure in three categories, depending on whether people are exposed to only the static field, to the static plus switched gradient fields or to the static plus switched gradient plus RF fields, as a basis for exposure assessment in epidemiological studies.
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Estudios Epidemiológicos , Imagen por Resonancia Magnética/instrumentación , Exposición Profesional/clasificación , Animales , Humanos , Campos Magnéticos/efectos adversos , Exposición Profesional/análisis , Dosis de Radiación , Ondas de Radio/efectos adversosRESUMEN
The central nervous system is the most likely target of mobile telephony radiofrequency (RF) field exposure in terms of biological effects. Several electroencephalography (EEG) studies have reported variations in the alpha-band power spectrum during and/or after RF exposure, in resting EEG and during sleep. In this context, the observation of the spontaneous electrical activity of neuronal networks under RF exposure can be an efficient tool to detect the occurrence of low-level RF effects on the nervous system. Our research group has developed a dedicated experimental setup in the GHz range for the simultaneous exposure of neuronal networks and monitoring of electrical activity. A transverse electromagnetic (TEM) cell was used to expose the neuronal networks to GSM-1800 signals at a SAR level of 3.2 W/kg. Recording of the neuronal electrical activity and detection of the extracellular spikes and bursts under exposure were performed using microelectrode arrays (MEAs). This work provides the proof of feasibility and preliminary results of the integrated investigation regarding exposure setup, culture of the neuronal network, recording of the electrical activity, and analysis of the signals obtained under RF exposure. In this pilot study on 16 cultures, there was a 30% reversible decrease in firing rate (FR) and bursting rate (BR) during a 3 min exposure to RF. Additional experiments are needed to further characterize this effect.
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Teléfono Celular , Red Nerviosa/citología , Red Nerviosa/efectos de la radiación , Neuronas/citología , Neuronas/efectos de la radiación , Ondas de Radio/efectos adversos , Animales , Corteza Cerebral/citología , Proyectos Piloto , Radiometría , Ratas , Ratas Sprague-DawleyRESUMEN
Introduction: The current deployment of the fifth generation (5G) of wireless communications raises new questions about the potential health effects of exposure to radiofrequency (RF) fields. So far, most of the established biological effects of RF have been known to be caused by heating. We previously reported inhibition of the spontaneous electrical activity of neuronal networks in vitro when exposed to 1.8 GHz signals at specific absorption rates (SAR) well above the guidelines. The present study aimed to assess the effects of RF fields at 3.5 GHz, one of the frequencies related to 5G, on neuronal activity in-vitro. Potential differences in the effects elicited by continuous-wave (CW) and 5G-modulated signals were also investigated. Methods: Spontaneous activity of neuronal cultures from embryonic cortices was recorded using 60-electrode multi-electrode arrays (MEAs) between 17 and 27 days in vitro. The neuronal cultures were subjected to 15 min RF exposures at SAR of 1, 3, and 28 W/kg. Results: At SAR close to the guidelines (1 and 3 W/kg), we found no conclusive evidence that 3.5 GHz RF exposure impacts the activity of neurons in vitro. On the contrary, CW and 5G-modulated signals elicited a clear decrease in bursting and total firing rates during RF exposure at high SAR levels (28 W/kg). Our experimental findings extend our previous results, showing that RF, at 1.8 to 3.5 GHz, inhibits the electrical activity of neurons in vitro at levels above environmental standards.
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Calefacción , NeuronasRESUMEN
The potential health risks of exposure to radiofrequency electromagnetic fields from mobile communications technologies have raised societal concerns. Guidelines have been set to protect the population (e.g. non-specific heating above 1 °C under exposure to radiofrequency fields), but questions remain regarding the potential biological effects of non-thermal exposures. With the advent of the fifth generation (5G) of mobile communication, assessing whether exposure to this new signal induces a cellular stress response is one of the mandatory steps on the roadmap for a safe deployment and health risk evaluation. Using the BRET (Bioluminescence Resonance Energy-Transfer) technique, we assessed whether continuous or intermittent (5 min ON/ 10 min OFF) exposure of live human keratinocytes and fibroblasts cells to 5G 3.5 GHz signals at specific absorption rate (SAR) up to 4 W/kg for 24 h impact basal or chemically-induced activity of Heat Shock Factor (HSF), RAt Sarcoma virus (RAS) and Extracellular signal-Regulated Kinases (ERK) kinases, and Promyelocytic Leukemia Protein (PML), that are all molecular pathways involved in environmental cell-stress responses. The main results are (i), a decrease of the HSF1 basal BRET signal when fibroblasts cells were exposed at the lower SARs tested (0.25 and 1 W/kg), but not at the highest one (4 W/kg), and (ii) a slight decrease of As2O3 maximal efficacy to trigger PML SUMOylation when fibroblasts cells, but not keratinocytes, were continuously exposed to the 5G RF-EMF signal. Nevertheless, given the inconsistency of these effects in terms of impacted cell type, effective SAR, exposure mode, and molecular cell stress response, we concluded that our study show no conclusive evidence that molecular effects can arise when skin cells are exposed to the 5G RF-EMF alone or with a chemical stressor.
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Campos Electromagnéticos , Quinasas MAP Reguladas por Señal Extracelular , Fibroblastos , Queratinocitos , Humanos , Campos Electromagnéticos/efectos adversosRESUMEN
We conducted a systematic review of scientific studies to evaluate whether the use of wireless phones is linked to an increased incidence of the brain cancer glioma or other tumors of the head (meningioma, acoustic neuroma, and parotid gland), originating in the areas of the head that most absorb radiofrequency (RF) energy from wireless phones. Epidemiology and in vivo studies were evaluated according to an agreed protocol; quality criteria were used to evaluate the studies for narrative synthesis but not for meta-analyses or pooling of results. The epidemiology study results were heterogeneous, with sparse data on long-term use (≥ 10 years). Meta-analyses of the epidemiology studies showed no statistically significant increase in risk (defined as P < 0.05) for adult brain cancer or other head tumors from wireless phone use. Analyses of the in vivo oncogenicity, tumor promotion, and genotoxicity studies also showed no statistically significant relationship between exposure to RF fields and genotoxic damage to brain cells, or the incidence of brain cancers or other tumors of the head. Assessment of the review results using the Hill criteria did not support a causal relationship between wireless phone use and the incidence of adult cancers in the areas of the head that most absorb RF energy from the use of wireless phones. There are insufficient data to make any determinations about longer-term use (≥ 10 years).
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Neoplasias Encefálicas/etiología , Teléfono Celular , Neoplasias Inducidas por Radiación/etiología , Adulto , Neoplasias Encefálicas/epidemiología , Estudios de Casos y Controles , Estudios de Cohortes , Glioma/epidemiología , Glioma/etiología , Humanos , Neoplasias Meníngeas/epidemiología , Neoplasias Meníngeas/etiología , Meningioma/epidemiología , Meningioma/etiología , Neoplasias Inducidas por Radiación/epidemiología , Neuroma Acústico/epidemiología , Neuroma Acústico/etiología , Neoplasias de la Parótida/etiología , Ondas de Radio/efectos adversos , Medición de Riesgo , Factores de RiesgoRESUMEN
An experimental approach was used to assess immunological biomarkers in the sera of young rats exposed in utero and postnatal to non-ionizing radiofrequency fields. Pregnant rats were exposed free-running, 2 h/day and 5 days/week to a 2.45 GHz Wi-Fi signal in a reverberation chamber at whole-body specific absorption rates (SAR) of 0, 0.08, 0.4, and 4 W/kg (with 10, 10, 12, and 9 rats, respectively), while cage control rats were kept in the animal facility (11 rats). Dams were exposed from days 6 to 21 of gestation and then three newborns per litter were further exposed from birth to day 35 postnatal. On day 35 after birth, all pups were sacrificed and sera collected. The screening of sera for antibodies directed against 15 different antigens related to damage and/or pathological markers was conducted using enzyme-linked immunosorbent assay (ELISA). No change in humoral response of young pups was observed, regardless of the types of biomarker and SAR levels. This study also provided some data on gestational outcome following in utero exposure to Wi-Fi signals. Mass evaluation of dams and pups and the number of pups per litter was monitored, and the genital tracts of young rats were observed for abnormalities by measuring anogenital distance. Under these experimental conditions, our observations suggest a lack of adverse effects of Wi-Fi exposure on delivery and general condition of the animals.
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Anticuerpos/sangre , Anticuerpos/inmunología , Exposición Materna/efectos adversos , Resultado del Embarazo , Tecnología Inalámbrica , Animales , Biomarcadores/sangre , Tamaño Corporal/efectos de la radiación , Parto Obstétrico , Femenino , Estudios de Seguimiento , Crecimiento y Desarrollo/efectos de la radiación , Tamaño de la Camada/efectos de la radiación , Embarazo , Ondas de Radio/efectos adversos , Ratas , Ratas WistarRESUMEN
BACKGROUND: The increase in exposure to the Wireless Fidelity (Wi-Fi) wireless communication signal has raised public health concerns especially for young people. Animal studies looking at the effects of early life and prenatal exposure to this source of electromagnetic fields, in the radiofrequency (RF) range, on development and behavior have been considered as high priority research needs by the World Health Organization. METHODS: For the first time, our study assessed the effects of in utero exposure to a 2450 MHz Wi-Fi signal (2 hr/day, 6 days/week for 18 days) on pregnant rats and their pups. Three levels in terms of whole-body specific absorption rate were used: 0.08, 0.4, and 4 W/kg. The prenatal study on fetuses delivered by caesarean (P20) concerned five females/group. The dams and their offspring were observed for 28 days after delivery (15 females/group). RESULTS: For all test conditions, no abnormalities were noted in the pregnant rats and no significant signs of toxicity were observed in the pre- and postnatal development of the pups, even at the highest level of 4 W/kg. CONCLUSIONS: In the present study, no teratogenic effect of repeated exposures to the Wi-Fi wireless communication signal was demonstrated even at the highest level of 4 W/kg. The results from this screening study aimed at investigating Wi-Fi effects, strengthen the previous conclusions that teratology and development studies have not detected any noxious effects of exposures to mobile telephony-related RF fields at exposure levels below standard limits.
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Campos Electromagnéticos/efectos adversos , Efectos Tardíos de la Exposición Prenatal/patología , Monitoreo de Radiación/métodos , Ondas de Radio/efectos adversos , Animales , Animales Recién Nacidos/crecimiento & desarrollo , Femenino , Embarazo , Ratas , Ratas Wistar , Reproducción , Pruebas de Toxicidad , Tecnología InalámbricaRESUMEN
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 γ-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°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.
Asunto(s)
Neuronas , Transmisión Sináptica , Potenciales de Acción/fisiología , Muscimol/farmacología , Neuronas/fisiología , Ondas de Radio , Transmisión Sináptica/fisiologíaRESUMEN
As of today, only acute effects of RF fields have been confirmed to represent a potential health hazard and they are attributed to non-specific heating (≥ 1 °C) under high-level exposure. Yet, the possibility that environmental RF impact living matter in the absence of temperature elevation needs further investigation. Since HSF1 is both a thermosensor and the master regulator of heat-shock stress response in eukaryotes, it remains to assess HSF1 activation in live cells under exposure to low-level RF signals. We thus measured basal, temperature-induced, and chemically induced HSF1 trimerization, a mandatory step on the cascade of HSF1 activation, under RF exposure to continuous wave (CW), Global System for Mobile (GSM), and Wi-Fi-modulated 1800 MHz signals, using a bioluminescence resonance energy transfer technique (BRET) probe. Our results show that, as expected, HSF1 is heat-activated by acute exposure of transiently transfected HEK293T cells to a CW RF field at a specific absorption rate of 24 W/kg for 30 min. However, we found no evidence of HSF1 activation under the same RF exposure condition when the cell culture medium temperature was fixed. We also found no experimental evidence that, at a fixed temperature, chronic RF exposure for 24 h at a SAR of 1.5 and 6 W/kg altered the potency or the maximal capability of the proteasome inhibitor MG132 to activate HSF1, whatever signal used. We only found that RF exposure to CW signals (1.5 and 6 W/kg) and GSM signals (1.5 W/kg) for 24 h marginally decreased basal HSF1 activity.
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Factores de Transcripción del Choque Térmico/metabolismo , Respuesta al Choque Térmico , Ondas de Radio/efectos adversos , Transferencia de Energía , Células HEK293 , Factores de Transcripción del Choque Térmico/análisis , Humanos , Mediciones LuminiscentesRESUMEN
Aim: The Pasche research group has reported that tumor-specific electromagnetic field frequencies have physiological and potential anti-tumor effects in cells, animals, and humans. Our aim was to investigate whether these fields have similar effects on physiological parameters in murine tumor models.Methods: Human HuH7 or HEPG2 cells were implanted in the right flank of 8-week-old female RAG gamma 2 C immunodeficient mice. An oximeter was used to record systolic blood pressure (pulse) in free-roaming conscious mice. Mice pulses were recorded and analyzed using a in-house software that also controlled the low-frequency generator for modulating the 27.12 MHz carrier wave at selected frequencies.Results: We performed exposures using both systematic scans at low frequencies and at the pre-determined frequencies reported by the Pasche group as altering both pulse and tumor growth in humans. Those exposures produced no detectable change in physiological parameters of tumor-bearing mice.Conclusion: No tumor-related frequencies were found, neither using systematic scans of frequencies nor published specific frequencies. There might obviously be differences between animal and human models, but our approach did not confirm the physiological data of the human Pasche group data.
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Carcinoma Hepatocelular/patología , Campos Electromagnéticos , Neoplasias Hepáticas/patología , Animales , Presión Sanguínea , Carcinoma Hepatocelular/terapia , Línea Celular Tumoral , Modelos Animales de Enfermedad , Femenino , Células Hep G2 , Humanos , Neoplasias Hepáticas/terapia , Ratones , Ratones SCID , Trasplante de Neoplasias , OximetríaRESUMEN
Purpose: The present study was conducted to re-evaluate the effect of low-level 1800 MHz RF signals on RAS/MAPK activation in live cells.Material and methods: Using 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 24 h 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. 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.Conclusions: 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.
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Transferencia de Energía , Quinasas MAP Reguladas por Señal Extracelular/metabolismo , Luminiscencia , Ondas de Radio , Proteínas ras/metabolismo , Línea Celular Tumoral , Supervivencia Celular/efectos de la radiación , HumanosRESUMEN
Salford et al. reported in 2003 that a single 2-h exposure to GSM-900 mobile telephony signals induced brain damage (increased permeability of the blood-brain barrier and presence of dark neurons) 50 days after exposure. In our study, 16 Fischer 344 rats (14 weeks old) were exposed head-only to the GSM-900 signal for 2 h at various brain-averaged SARs (0, 0.14 and 2.0 W/kg) or were used as cage or positive controls. Albumin leakage and neuron degeneration were evaluated 14 and 50 days after exposure. No apoptotic neurons were found 14 days after the last exposure using the TUNEL method. No statistically significant albumin leakage was observed. Neuronal degeneration, assessed using cresyl violet or the more specific marker Fluoro-Jade B, was not significantly different among the tested groups. No apoptotic neurons were detected. The findings of our study did not confirm the previous results of Salford et al.