Study type: Medical/biological study (experimental study)

Blood-brain barrier and electromagnetic fields: Effects of scopolamine methylbromide on working memory after whole-body exposure to 2.45 GHz microwaves in rats med./bio.

By: Cosquer B, Vasconcelos AP, Fröhlich J, Cassel JC
Published in: Behav Brain Res 2005; 161 (2): 229-237
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Aim of study (acc. to author)

To study whether a systemically-injected derivate of the muscarinic antagonist scopolamine hydrobromide (scopolamine methylbromide) altered maze performance of rats after a 45 min exposure to 2.45 GHz electromagnetic field.

Background/further details

First, it was verified that the maze test enabled demonstration of memory deficits in rats treated with the muscarinic antagonist scopolamine hydrobromide (0.5 mg/kg), which poorly crosses the blood-brain barrier and which is known to induce memory impairments. The drug was injected before and after irradiation.
Scopolamin methylbromide is another muscarinic antagonist that does not cross the blood-brain barrier easily; if observed such an alteration would reflect changes in blood-brain barrier permeability.
Finally, animals were subjected to injections of Evans blue, a dye binding serum albumin, before or after electromagnetic field exposure.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 2.45 GHz
Modulation type: pulsed
Exposure duration: continuous for 45 min
  • SAR: 3 mW/g average over time (partial body) (± 3 dB; brain average)
  • SAR: 2 mW/g average over time (whole body) (± 2 dB)

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
  • circular waveguides/93 cm long x 20 cm in diameter
Setup Rats (n=12) were placed individually in a transparent plastic chamber (20 cm long x 17.5 cm in diameter, 13.5 cm high) located in the middle of the waveguide where they were able to move freely. Two waveguides were simultaneously excited hence exposing two rats at a time.
Additional info Naive rats (n=12) were brought into the testing room in their home cages and were left in there for 45 min to serve as cage control.
Parameters
Measurand Value Type Method Mass Remarks
SAR 3 mW/g average over time estimated partial body ± 3 dB; brain average
SAR 2 mW/g average over time measured and calculated whole body ± 2 dB
Measurement and calculation details

SARs were determined both numerically and experimentally by using the FDTD method and measuring the field distribution inside the waveguide with DASY4, near field scanners.

Reference articles

  • Cassel JC et al. (2004): Whole-body exposure to 2.45 GHz electromagnetic fields does not alter radial-maze performance in rats

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

Whether scopolamine methylbromide was injected before or after exposure, the exposed animals did not perform differently from the naive (no experience of the exposure device) or sham-exposed rats. Thus, electromagnetic fields most probably failed to disrupt the blood-brain barrier. This conclusion was further supported by the absence of Evans blue extravasation into the brain parenchyma of the exposed animals.

Study character:

Study funded by

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