ID Number		664
Study Type		In Vivo
Model		2450 MHz (CW) exposure to rats and mice and analysis of behavior and opioid response
Details		Swiss-Webster mice were exposed to 2450 MHz (CW) MW for 10 minutes at SARs of up to 45.5 W/kg in a waveguide. Exposure elevated body temperature and increased analgesia (using an abdominal constriction assay) in a SAR-dose dependent manner. MW induced analgesia, but not MW hyperthermia, was attenuated by the general opiod blockers naltrexone and naloxone, and by blockers specific for mu- and kappa-opioid receptors suggesting MW induced analgesia is mediated by mu- and kappa-opioid mechanisms. Further studies showed MW exposure did not affect levels of methionine-enkephalin (ME) or Beta-Endorphin (Beta-EP) in the cerebral cortex or in the corpus striatum/brainstem of the brain. The authors conclude antinociceptive effects of MW exposure are mediated by opioids other than ME and beta-EP, or that regional levels do not reflect changes between stored and functionally active peptides. In other studies, CD1 mice were treated with chlordiazepoxide (CDZ) and exposed to 1.8 or 4.7 GHz (CW) MW for 5 minutes at SARs up to 36 W/kg in restraining tubes in an anechoic chamber and performance on a staircase test was analyzed. MW exposure at both 1.8 and 4.7 GHz antagonized CDZ sedation, but only 4.7-GHz radiation antagonized CDZ anxiolysis. The difference was attributed to different energy deposition patterns - 1.8 GHz is the resonant frequency in mice and likely result in a deeper energy absorption, while 4.7 GHz would give increased peripheral energy deposition and be more likely to induce stress counteracting the effect of CDZ. In studies looking at the effects of methylatropine to antagonize central cholinomimetic drug effects (Fed Proc, 1982, 41:1576), carbidopa (CD) or 6-hydroxoydopamine (6-HD) to decrease brain norepinephrine and dopamine levels (Fed Proc (1983) 42(4):1122), domperidon to induce climbing behavior (Bioelectromagnetics (1987) 8:45-55), morphine to induce a tail-flick response and its antagonists (J Bioelectr (1986) 5:35-46) and of pilocarpine to induce hypothermia and oxotremorine to induced ataxia and their antagonists (Radiat Res (1986) 105:328-340), the effects of drugs were enhanced by MW exposure. The authors suggest MWs facilitate drug action by increasing permeability across the blood brain barrier.
Findings		Effects (only at thermal levels)
Status		Completed With Publication
Principal Investigator		Univ henri Poincare, Nancy France
Funding Agency		AF, USA
Country		UNITED STATES
References		Quock, RM et al. Radiat. Res., (1986) 105:328-340 Quock, RM et al. Pharmacol. Biochem. Behav., (1994) 47:845-849
Comments		There is no positive (heat) control and no actual monitoring of animal core temperature in many of the above studies, although the high SAR would make it probable that thermal levels were experienced by the mice.