Lai H, Horita A, Guy AW (1994)
previous research these authors reported that rats exposed
for 45minutes to pulsed 2450 MHz microwaves showed a deficit
in learning to perform in the radial-arm maze. This task involves
spatial memory functions. The objective of the present research
was to investigate the brain mechanisms involved in the previously
observed spatial memory deficit.
The microwave-exposed rats learned significantly slower than the sham-exposed animals. Pre-treatment with physostigmine or naltrexone reversed this deficit, but naloxone did not. The authors hypothesize that the spatial memory deficits are caused by activation of central opioids, which in turn leads to a decrease in cholinergic activity in the hippocampus and frontal cortex. Physostigmine stimulates this cholinergic function and naltrexone blocks the action of the opioids. Naloxone only affects peripheral opioids, and, therefore, had no effect on the observed spatial memory deficit.