Study type: Medical/biological study (experimental study)

Intraseptal microinjection of beta-funaltrexamine blocked a microwave-induced decrease of hippocampal cholinergic activity in the rat med./bio.

By: Lai H, Carino MA, Horita A, Guy AW
Published in: Pharmacol Biochem Behav 1996; 53 (3): 613-616
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Aim of study (acc. to author)

To investigate neural mechanisms affected by microwave exposure. The aim of the study was to investigate the brain site where endogenous opioids act to cause a decrease in cholinergic activity in the hippocampus by microinjecting the µ-opioid antagonist beta-funaltrexamine into the brain in an attempt to block inhibitory effect of microwaves.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 2.45 GHz
Modulation type: pulsed
Exposure duration: continuous for 45 min
  • power density: 1 mW/cm² spatial average
  • SAR: 0.6 W/kg average over mass (whole body) ([Chou et al., 1984])

Exposure 1

Main characteristics
Frequency 2.45 GHz
Type
Charakteristic
  • guided field
Polarization
  • circular
Exposure duration continuous for 45 min
Modulation
Modulation type pulsed
Pulse width 2 µs
Repetition frequency 500 Hz
Exposure setup
Exposure source
Setup The exposure system consisted of eight individual cylindrical waveguide exposure tubes made of galvanized wire screen and operating in TE11 mode. Each tube contained a plastic chamber to house a rat.
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
power density 1 mW/cm² spatial average - - -
SAR 0.6 W/kg average over mass measured whole body [Chou et al., 1984]

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)

Acute exposure to pulsed 2450-MHz microwaves at a power density of 1 mW/cm² caused a decrease in cholinergic activity in the hippocampus of the rat. Microinjection of beta-funaltrexamine into the septum before exposure blocked this effect. These findings indicate that µ-opioid receptors in the septum mediate a microwave-induced decrease in cholinergic activity and support the authors' hypothesis that microwaves at a whole body SAR of 0.6 W/kg can activate endogenous opioids in the brain.

Study character:

Study funded by