ID Number		625
Study Type		In Vivo
Model		2450 MHz (CW, PW) exposure to rats and analysis of performance in a radial arm maze
Details		Sprague-Dawley rats were exposed to 2450 MHz RF (PW - 2 microsecond duration, 500 pulses per second) for 45 minutes at an average whole-body SAR of 0.6 W/kg (±2 dB) and tested for anxiety levels using a plus-maze and either high or low ambient light conditions. The study was designed as a replication / verification of a series of reports by Lai et al (1994 - 2000) as well as a subsequent verification attempt by Cobb et al (2003). The 45 minute exposure did not increase or decrease rat anxiety as assessed using the maze testing, and thus did not confirm the original reports by Lai et al. In a side experiment, the authors confirmed habituation to one new situation may lower an animal's fear in a later confrontation to a different new situation. They also observed a significant effect of light intensity on maze behavior, but no interaction effect between light and RF exposure. Additional studies using the above exposure conditions and a maze test based on unrestrained access to spatial cues (no walls) as well as a maze apparatus bordered by 30 cm high opaque walls were also reported in subsequent papers (Behav Brain Res 2005, 161:331-334; Behav Brain Res 2005, 156(1):65-74). The authors could not replicate the earlier results of Lai et al and suggest that RF exposure does not alter spatial working memory when access to spatial cues is reduced. Further studies investigated whether the above RF exposure using a whole body SAR of 2 W/kg (brain avg SAR of 3 W/kg) had an effect on memory deficits in rats treated with a quaternary-ammonium derivate scopolamine hydrobromide (a muscarinic receptor antagonist that does not readily cross the blood brain barrier). The authors report no effect of exposure (even at these higher SAR levels) and conclude that exposure must not disrupt the blood brain barrier. Supportive evidence from subsequent histopathological evaluation of Evans blue extravasation into the brain parenchyma confirmed this result.
Findings		No Effects
Status		Completed With Publication
Principal Investigator		Univ. Louis Pasteur, France - jean-christophe.cassel@psycho-ulp.u-strasbg.fr
Funding Agency		EU, MMF
Country		FRANCE
References		Cosquer, B et al. Behav Brain Res, (2005) 161:229-237 Cosquer, B et al. Behav Brain Res, (2005) 161:331-334 Cosquer , B et al. Behav Brain Res, (2005) 156:65-74 Cassel , JC et al. Behav Brain Res, (2004) 155:37-43
Comments		Lai reported that RF exposure altered spatial working memory of rats in a radial maze, and correlated this with an increase in benzodiazepine receptors in the cerebral cortex. However Cosquer et al. (2005) state in their replication attempt paper that the literature shows stressful situations are associated with a decreased number of benzodiazepine receptors, not an increase. IN the subsequent study using the muscarinic receptor antagonist, it would have been nice to have a positive control used WITH the drug that did disrupt the BBB and see the effect, then show RF did not disrupt the BBB (but oh well, relatively good study non-the-less).