Study type: Medical/biological study (experimental study)

Transient and steady-state magnetic fields induce increased fluorodeoxyglucose uptake in the rat hindbrain. med./bio.

Published in: Synapse 2011; 65 (7): 617-623

Aim of study (acc. to author)

The authors wanted to extend results from previous studies and to study whether electromagnetic field transduction was dependent on the direction of the field, and whether the previously reported electromagnetic field effects on fluorodeoxyglucose (FDG) uptake (see Frilot 2nd et al. 2009) actually were related to those field effects.

Background/further details

20 rats were divided into two groups for two experiments (each experiment: n=10 rats): In the first experiment the rats were restrained so that the field was applied coronally, orthogonal to the sagittal plane. In the second experiment each rat was free to roam in the cage during exposure, resulting in a random vector relation between the field and the long axis of the rat.
In the first experiment, each rat was injected (with 18F-labeled FDG) and scanned three times: once after field exposure using a 100% duty cycle (field 1), once using a 50% duty cycle (field 2), and once after sham exposure. In the second experiment the rats were injected and scanned twice, once after field exposure for 45 min using a 50% duty cycle (field 3) and once after sham exposure. The minimum time between injections was two days.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 60 Hz
Modulation type: pulsed
Exposure duration: continuous for 45 min
Exposure 2: 60 Hz
Modulation type: pulsed
Exposure duration: 2 s on - 2 s off - for 45 min
Exposure 3: 60 Hz
Modulation type: pulsed
Exposure duration: 2 s on - 2 s off - for 45 min
rats free to roam in the cage

General information

all rats were injected with 11 MBq of 18F-labeled FDG before exposure or sham exposure

Exposure 1

Main characteristics
Frequency 60 Hz
Type
Exposure duration continuous for 45 min
Additional info rats immobilized
Modulation
Modulation type pulsed
Rise time 10 ms
Fall time 10 ms
Duty cycle 100 %
Exposure setup
Exposure source
Chamber square coil; field uniform within 10 % in the exposure area; rats placed in a restrainer; exposure coronally, orthogonal to the sagittal plane
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 25 mT effective value - - -

Exposure 2

Main characteristics
Frequency 60 Hz
Type
Exposure duration 2 s on - 2 s off - for 45 min
Additional info rats immobilized
Modulation
Modulation type pulsed
Rise time 10 ms
Fall time 10 ms
Duty cycle 50 %
Exposure setup
Exposure source
Chamber rats placed in a restrainer
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 25 mT effective value - - -

Exposure 3

Main characteristics
Frequency 60 Hz
Type
Exposure duration 2 s on - 2 s off - for 45 min
Additional info rats free to roam in the cage
Modulation
Modulation type pulsed
Rise time 10 ms
Fall time 10 ms
Duty cycle 50 %
Exposure setup
Exposure source
Chamber rats free to raom in the cage
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 25 mT effective value - - -

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

Increased glucose utilization occurred in hindbrain voxels when the field was applied orthogonally to the sagittal plane (50% and 100% (lesser extent) duty cycle), but not when the angle between the field and the sagittal plane varied randomly (field 3). Distinct FDG activation effects were observed in response to transient (i.e. 50% duty cycle) and steady-state (i.e. 100% duty cycle) magnetic stimuli.
Observations of increased glucose utilization induced by magnetic stimuli (magnetic fields induce electric fields in the body) and its dependence on the direction of the field suggest that signal transduction was mediated by a force detector (electric field exerts force on negatively-charged oligosaccharide side chains bound to an ion channel gate, thereby mechanically opening gate) and that the process and/or early post-transduction processing occur in the hindbrain.

Study character:

Study funded by

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