Study type: Medical/biological study (experimental study)

Exposure to AC and DC magnetic fields induces changes in 5-HT1B receptor binding parameters in rat brain membranes med./bio.

By: Espinosa JM, Liberti M, Lagroye I, Veyret B
Published in: Bioelectromagnetics 2006; 27 (5): 414-422
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Aim of study (acc. to author)

To study the binding properties of the G-protein coupled receptor serotonin 5-HT1B receptor under exposure to AC (50 and 400 Hz) and DC magnetic fields in rat brain membranes.

Background/further details

The study was an attempt to replicate earlier positive findings (see publication 3968) where it was shown that exposure to 50 Hz magnetic fields (above 0.6 mT) caused a reversible decrease of the 5-HT1B serotoninergic receptor affinity in rat brain membranes.
In the present investigation the 5-HT1B receptor affinity was measured using saturation binding techniques. Using radioactive [³H]5-HT first the authors attempted to confirm that a 50 Hz magnetic field exposure induces a decrease of the receptor affinity. Then, the roles of both induced currents and static magnetic fields in the elicitation of the effect was determined.
The 5-HT1B receptor is the major presynaptic serotoninergic receptor and thus controls the release of serotonin as well as other neurotransmitters.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 50 Hz
Exposure duration: continuous for 60 min
Exposure 2: 400 Hz
Exposure duration: continuous for 60 min
Exposure 3:
Exposure duration: continuous for 60 min

Exposure 1

Main characteristics
Frequency 50 Hz
Type
Waveform
Exposure duration continuous for 60 min
Additional info Vertical magnetic field
Exposure setup
Exposure source
Setup 96 well plates containing the rat brain membranes were located inside each set of coils. Sham exposure took place at the same location for the same amount of time but the coils were not activated.
Additional info The magnetic field uniformity was within 2% over 20 x 20 cm² area.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1.1 mT effective value unspecified - 0.5 mT and 0.1 mT
current density 0.2 mA/m² unspecified unspecified - at 1.1 mT

Exposure 2

Main characteristics
Frequency 400 Hz
Type
Waveform
Exposure duration continuous for 60 min
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 0.675 mT effective value unspecified - -
current density 0.98 mA/m² - unspecified - -

Exposure 3

Main characteristics
Frequency
Type
Exposure duration continuous for 60 min
Exposure setup
Exposure source
Setup same as in E1
Additional info The magnetic field was uniform within 8% across the multiwell plates.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 11 mT - unspecified - and 1.1 mT

Reference articles

  • Massot O et al. (2000): Magnetic field desensitizes 5-HT(1B) receptor in brain: pharmacological and functional studies

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

The replication of the previous study was successful, as similar increases in both binding parameters KD (equilibrium dissociation constant) and Bmax (total number of binding sites/maximum binding of radioligand) at around 1 mT were found in the two laboratories, using the same exposure system.
Exposure of the membranes at 400 Hz (0.675 mT) did not elicit a larger increase in KD in spite of a much larger induced current density.
Exposure to DC fields (1.1 and 11 mT) did not induce major increases in KD and Bmax.
Modeling of the receptor-ligand-G protein interactions yielded good fits for all data and that of the previous study, showing that the AC field may act by decreasing the ability of the G-protein to alter the ligand-receptor affinity. The hypothesis is that the bipolar nature of the AC field explains the different nature of the effects observed with AC and DC exposures.

Study character:

Study funded by

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