Repeated exposure to low-level extremely low frequency-modulated microwaves affects baseline and scopolamine-modified electroencephalograms in freely moving rats.
OBJECTIVE
To compare in the electroencephalogram of rats the effects of scopolamine (an acetylcholine receptor antagonist) alone and after repeated exposure to low-level microwaves modulated at extremely low frequency.


METHODS
Averaged frequency spectra (0.5-30 Hz) of the electroencephalogram were studied in freely moving rats with carbon electrodes implanted into the somatosensory cortex. The rats were repeatedly (3 days, 30 min day(-1)) exposed to low-intensity (approximately = 0.3 mW cm(-2)) microwaves (915 MHz, 20-ms pulse duration), amplitude modulated (square-wave) at extremely low frequency (4 Hz).


RESULTS
The exposure to extremely low frequency microwaves alone significantly enhanced the fast electroencephalographic rhythms (18-30 Hz). This effect was observed neither in subsequent sham-exposure experiment nor in radiation-naïve animals. In the microwave-exposed rats, scopolamine (0.1 mg kg(-1), subcutaneously) did not cause a slowing in the electroencephalogram that was shown in non-exposed rats. A similarity between the scopolamine-induced electroencephalogram effect in the microwave-exposed rats and that of physostigmine (enhancing the acetylcholine level in the brain) in radiation-naïve animals was noted. This paradoxical phenomenon stimulates new experimentation for understanding its mechanism(s).


CONCLUSIONS
The data obtained provide additional evidence that repeated low-level exposure to extremely low frequency microwaves can modify an activity of cholinergic system in the brain.
Vorobyov
V
V
Institute of Cell Biophysics, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia. VorobyovV@Cardiff.ac.uk
Pesić
V
V
Janać
B
B
Prolić
Z
Z
D000818:Animals; D004307:Dose-Response Relationship, Radiation; D004351:Drug Resistance / Q000528:radiation effects; D004569:Electroencephalography / Q000187:drug effects* / Q000528:radiation effects*; D008297:Male; D008872:Microwaves; D018727:Muscarinic Antagonists / Q000494:pharmacology; D011829:Radiation Dosage; D011836:Radiation Tolerance / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D012601:Scopolamine / Q000494:pharmacology*; D013003:Somatosensory Cortex / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects
D018727:Muscarinic Antagonists; D012601:Scopolamine