Study type: Medical/biological study (experimental study)

Naltrexone pretreatment blocks microwave-induced changes in central cholinergic receptors med./bio.

Published in: Bioelectromagnetics 1991; 12 (1): 27-33

Aim of study (acc. to author)

To clarify neural mechanism involved in the effects of low-level microwave exposure on the functions of the central cholinergic systems.

Background/further details

The authors investigated the effect of pretreatment with the narcotic antagonist naltrexone on microwave-induced changes in muscarinic cholinergic receptors. Because the acute effect can be blocked by naltrexone, it is expected that the neurological consequences of repeated irradiation (i.e. changes in neurotransmitter receptor concentrations) also can be blocked.



Exposure Parameters
Exposure 1: 2.45 GHz
Modulation type: pulsed
Exposure duration: 10 x (20 min or 45 min); 1 exposure per day.

General information

Four conditions were used: microwave + naltrexone hydrochloride injection( 1 ml/kg), sham exposure + naltrexone, microwave + saline (1 ml/kg) and sham exposure + saline.

Exposure 1

Main characteristics
Frequency 2.45 GHz
  • guided field
  • circular
Exposure duration 10 x (20 min or 45 min); 1 exposure per day.
Modulation type pulsed
Pulse width 2 µs
Repetition frequency 500 Hz
Exposure setup
Exposure source
Chamber mirowave irradiation room
Measurand Value Type Method Mass Remarks
SAR 600 µW/g mean calculated whole body determined calorimetrically.
power density 10 W/m² mean cf. remarks - within the waveguide

Reference articles

  • Guy AW et al. (1979): Circularly polarized 2450 MHz waveguide system for chronic exposure of small animals to microwaves

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Investigated organ system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

Repeated irradiation of rats to pulsed microwaves induced biphasic changes in the concentration of muscarinic cholinergic receptors in the CNS: An increase in receptor concentration occured in the hippocampus of rats subjected to ten 45-min sessions of microwave exposure, whereas a decrease in receptor concentration was observed in the frontal cortex and hippocampus of animals exposed to ten 20-min sessions. The drug pretreatment blocked the microwave-induced changes in cholinergic receptors in the brain.
The results support the author's hypothesis that endogenous opioids play a role in the effects of microwaves on central cholinergic systems.

Study character:

Study funded by