Study type: Medical/biological study (experimental study)

An increase in glial fibrillary acidic protein follows brain hyperthermia in rats. med./bio.

Published in: Brain Res 1987; 415 (2): 371-374

Aim of study (acc. to author)

The aim of the study was to examine the effects of microwave-induced hyperthermia of the CNS on the concentration of glial fibrillary acidic protein (GFAP) in several brain ragions of rats.

Background/further details

Glial fibrillary acidic protein (GFAP) is the major protein of glial intermediate filaments in astrocytes and it has been proposed as a marker for assessing astrocytic response to injury.
Two experiments were performed: Field 1) Rats were exposed and killed one, seven, or 14 days after exposure (5 rats for each condition). Field 2) Rats were exposed and killed seven or 14 days after exposure (4 rats for each condition).

Endpoint

Exposure

Exposure Parameters
Exposure 1: 2.45 GHz
Exposure duration: 220 ms
Exposure 2: 2.45 GHz
Exposure duration: continuous for 3 hr/day on 3 consecutive days

Exposure 1

Main characteristics
Frequency 2.45 GHz
Type
Exposure duration 220 ms
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
power density 811 W/cm² peak value - - -
power density 258 W/cm² average over time - - -

Exposure 2

Main characteristics
Frequency 2.45 GHz
Type
Exposure duration continuous for 3 hr/day on 3 consecutive days
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
power density 3.1 W/cm² peak value - - -
power density 0.009 W/cm² average over time - - -

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

Exposure resulted in a time-related increase in GFAP in olfactory bulbs and cortex, areas of maximum heating. Striatum and cerebellum were not affected. The increase in GFAP following a brain temperature increase suggests that heating of brain tissue may be sufficient to provoke an injury response comparable to that caused by chemical and physical insult. Rectal temperature was not affected. Levels of GFAP were not changed when animals were exposed for much longer periods of time to microwave power density levels that do not increase brain temperatures.

Study character:

Study funded by

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