Effects of 900 MHz radiofrequency on corticosterone, emotional memory and neuroinflammation in middle-aged rats

International audienceThe widespread use of mobile phones raises the question of the effects of electromagnetic fields (EMF, 900 MHz) on the brain. Previous studies reported increased levels of the glial fibrillary acidic protein (GFAP) in the rat's brain after a single exposure to 900 MHz global system for mobile (GSM) signal, suggesting a potential inflammatory process. While this result was obtained in adult rats, no data is currently available in older animals. Since the transition from middle-age to senescence is highly dependent on environment and lifestyle, we studied the reactivity of middle-aged brains to EMF exposure. We assessed the effects of a single 15 min GSM exposure (900 MHz ; specific absorption rate (SAR)=6 W/kg) on GFAP expression in young adults (6 week-old) and middle-aged rats (12 month-old). Brain interleukin (IL)-1ß and IL-6, plasmatic levels of corticosterone (CORT), and emotional memory were also assessed. Our data indicated that, in contrast to previously published work, acute GSM exposure did not induce astrocyte activation. Our results showed an IL-1ß increase in the olfactory bulb and enhanced contextual emotional memory in GSM-exposed middle-aged rats, and increased plasmatic levels of CORT in GSMexposed young adults. Altogether, our data showed an age dependency of reactivity to GSM exposure in neuro-immunity, stress and behavioral parameters. Reproducing these effects and studying their mechanisms may allow a better understanding of mobile phone EMF effects on neurobiological parameters

Impact of stress on electromagnetic field-induced corticosterone, cytokines and GFAP responses

The widespread use of mobile phones raises the question of the effects of electromagnetic fields (EMF, 900 MHz) on the brain. Experimentally, local brain EMF exposures are performed in rats maintained in contention in Plexiglas rockets. Previous studies reported increased levels of cerebral glial fibrillary acidic protein (GFAP) after a single EMF exposure, suggesting a potential inflammatory process. However, these effects were not always reproduced, and the present study aims to test the contribution of protocol-induced stress in EMF-induced responses. To do so, plasmatic levels of corticosterone, GFAP, interleukin (IL)-1ß and IL-6 were measured 48 h following a single, 15 min, (0 or 6 W/kg) EMF-exposure in rats subjected to fear conditioning and tests (group 1 and 2). Test of stress was performed by measuring the same biological responses 30 min, 5 h and 24 h following (group 3) daily handling, (groups 4 and 5) a single, 15 min, (0 or 6 W/kg) GSM-exposure, and (group 6) a single 15 min sham (0W/kg GSM)-exposure followed by a fear conditioning session. Results showed that corticosterone increase was found only in groups 2 and 6, and no effect on IL-1ß, IL-6 or GFAP was obtained. According to these data, stressful situation linked to fear conditioning procedure did not modify GFAP or IL responses. Moreover, according to corticosterone measure, acute 15 min contention did not appear as a stressful event in our study. The use of fear conditioning in our protocol and the demonstration that it increases corticosterone after 30 min must be highlighted as a possible interacting parameter. Identification of contention-linked side effects may allow a better understanding of mobile phone EMF effects on neurobiological parameters