Study type: Medical/biological study (experimental study)

Single vs. repeated microwave exposure: effects on benzodiazepine receptors in the brain of the rat med./bio.

Published in: Bioelectromagnetics 1992; 13 (1): 57-66

Aim of study (acc. to author)

To study the effects of single (45 min) and repeated (ten daily 45-min sessions) microwave exposures on the concentration and affinity of benzodiazepine receptors in the hippocampus, cerebellum, and cerebral cortex of the rat.

Background/further details

The benzodiazepine receptors coupled to GABA receptors and chloride channels play a significant role in mediating stress and anxiety responses in animals. In addition, a separate experiment was done to investigate whether factors in the irradiation environment contribute to the effect of microwaves on benzodiazepine receptors: Rats were adapted to the exposure environment before exposure to microwaves. The animals were placed in waveguides, given food and water, and after 24 h were subjected to microwave or sham irradiation for 45 min.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 2.45 GHz
Modulation type: pulsed
Exposure duration: continuous for 45 min
Exposure 2: 2.45 GHz
Modulation type: pulsed
Exposure duration: 45 min/day for 10 days

Exposure 1

Main characteristics
Frequency 2.45 GHz
Type
Polarization
  • circular
Exposure duration continuous for 45 min
Modulation
Modulation type pulsed
Pulse width 2 µs
Packets per second 500
Exposure setup
Exposure source
Setup cylindrical Plexiglas chamber with a diameter of 15 cm, 24 cm long inside the waveguide
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
power density 1 mW/cm² - - - -
SAR 0.6 W/kg average over mass calculated whole body -

Exposure 2

Main characteristics
Frequency 2.45 GHz
Type
Polarization
  • circular
Exposure duration 45 min/day for 10 days
Modulation
Modulation type pulsed
Pulse width 2 µs
Packets per second 500
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
power density 1 mW/cm² - - - -
SAR 0.6 W/kg average over mass calculated whole body -

Reference articles

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

After a single exposure, an increase in the concentration of receptor was observed in the cerebral cortex, but no significant effect was observed in the hippocampus or cerebellum. No significant change in binding affinity of the receptors was observed in any of the brain regions investigated. In animals subjected to repeated exposures, no significant change in receptor concentration was found in the cerebral cortex immediately after the last exposure, which may indicate an adaptation to repeated exposures. The results also show that handling and exposure procedures in the experiments did not significantly affect benzodiazepine receptors. Because benzodiazepine receptors in the brain are responsive to anxiety and stress, the data support the hypothesis that low-intensity microwave exposure can be a source of stress.

Study character:

Study funded by