ID Number		860
Study Type		In Vivo
Model		600 MHz (CW), 5 GHz (PW) exposure to rats and analysis of brain activity and behavior
Details		Sprague Dawley rats were exposed to 600 MHz (CW) RF for 20 minutes prior to performance of a memory task (remembering recently explored objects). Both core body and brain dura temperatures were monitored during exposure. In addition, brain histochemistry was performed to look at c-fos expression. Exposures at 0 and 0.1 W/kg had no effect on performance, core or dura temperature, or c-fos expression. Rats exposed to 5-10 W/kg showed an incremental rise in core and brain temperature, and correspondingly showed a dose dependent decrease in memory performance and elevated c-fos levels in the periventricular strata, hypothalamic nuclei, amygdala, and several other areas of the brain consistent with a stress response. At 1 W/kg exposure, a modest elevation of brain dura was recorded as well as a small decrease in working memory performance. The authors conclude the effects were the result of temperature influences of the microwave exposure. In a follow-up study in 1998, the authors showed that pre-exposure to 600 MHz (CW) RF for 20 minutes per day for either 1 or 5 days at 9.3 W/kg could tolerize rats to the hyperthermic effects of exposure on behavior. In addition, such hyperthermic effects could also be blocked by injection with the opioid receptor antagonist naloxone just prior to MW exposure, suggesting a role of opioids in the hyperthermic response. In related studies, rats exposed to 5 GHz (PW - 10 usec pulse width, 1000 pps) RF at thermal levels (SAR on right and left sides of the brain were 29 and 40 W/kg and temp maintained at approximately 41.2 and 41.7 degrees C, respectively) for 40 minutes were analyzed by collection of extracellular amino acids from the hypothalamus and caudate nucleus via implanted microdialysis probe and temperature probe guides. The authors report exposures resulted in increased aspartic acid, serine, and glycine, and conclude that thermal stress induces amino acid changes that are not restricted to thermoregulatory centers
Findings		Effects (only at thermal levels)
Status		Completed With Publication
Principal Investigator		Brooks AFB, TX, USA
Funding Agency		AF, USA
Country		UNITED STATES
References		Mickley, GA et al. Physiol Behav, (1994) 55:1029-1038 Mickley, GA et al. Physiol Behav, (1998) 63:855-865 Mason, PA et al. Bioelectromagnetics, (1997) 18:277-283
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