Excitatory synaptic transmission in the rat perirhinal cortex is not affected by acute exposure to low-level continuous wave or GSM 900 MHz radiofrequency.

The recent increase in the use of cellular phones has raised public concern about health risk associated with brain exposure to radio frequency electromagnetic fields (RF-EMF). As actual exposure limits proposed by the European Community are below the RF intensities able to produce temperature increase in a biological sample, recent studies (Platano et al, Bioelectromagnetics 2007, 28:599-607) have focused on possible non-thermal effects associated to these doses. Aim of the present study was to verify if acute exposure to 900 MHz RF-EMF continuous wave (CW) or amplitude-modulated according to global system mobile communication standard (GSM) could affect excitatory synaptic transmission in the cerebral cortex in rat brain slices. Experiments were carried out in 400 micrometers horizontal brain slices including the perirhinal cortex, prepared from 25-50 day-old Sprague Dawley male rats. Extracellular field potentials evoked by horizontal fibres stimulation (0.2 ms, 0.033 Hz) were recorded in layer II/III of the perirhinal cortex, and the synaptic peak amplitude was measured. During field potential recording, slices were exposed for 5 min to 900 MHz CW or GSM RF-EMF; the specific absorption rates (SARs) were 2 W/kg for CW and 2 W/kg (time average value) for GSM. The exposure system, especially designed for electrophysiological measurements, allowed an accurate dosimetry on the biological sample (Paffi et al., IEEE Trans. Microw. Theory Tech., 2007, 55:2463-2471). The results obtained to date indicate that acute exposure to 2 W/kg CW (n=6) or 2 W/kg GSM (n=14) 900 MHz RF-EMF do not significantly alter the excitatory synaptic transmission in the rat perirhinal cortex.