Study type: Medical/biological study (experimental study)

Antidepressant-like effects of cranial stimulation within a low-energy magnetic field in rats. med./bio.

Published in: Biol Psychiatry 2005; 57 (6): 571-576

Aim of study (acc. to author)

To study whether a low-energy component of echo planar magnetic resonance spectroscopic imaging (low-field magnetic stimulation) has antidepressant-like, locomotor-stimulating, or amnestic effects in rats. The forced swim test was used.

Background/further details

The forced swim test is an animal model often used in the study of depression. It is a 2-day helplessness procedure in which rats swim under conditions in which escape is not possible.
Additionally, the effects on activity in an open field were examined to ensure that the effects that were observed in the forced swim test were not due to nonspecific effects on locomotion.
Rats were also used to confirm the efficacy of systemic doses of the standard antidepressant drugs fluoxetine or desipramine in the forced swim test.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 1 kHz
Exposure duration: 20 min
Exposure 2:
Exposure duration: 20 min
-

General information

Following treatments were used: LFMS (low field magnetic stimulation) within the focal point of the field, LFMS outside the focal point (10% LFMS), no field, constant DC, fluoxetine (20 mg/kg, IP) and desipramine (10 mg/kg, IP).

Exposure 1

Main characteristics
Frequency 1 kHz
Type
Waveform
  • sawtooth-shaped
Exposure duration 20 min
Modulation
Modulation type cf. additional info
Additional info

Low field magnetic stimulation (LMFS) consisting of 512 alternating trapezoids of 1 ms each. Electric field consisting of 512 square electric pulses of 0.25 ms each.

Exposure setup
Exposure source
Chamber exposure cylinder/35.56 cm in diameter x 45.72 cm long x 1.59 cm think
Setup 1h, 19 h or 23 h after forced swimming session, the rats were restrained individually in a plastic tube which was placed in the exposure cylinder. At 24 hours after the forced swim, rats were retested for 5 min under identical conditions.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 600 µT peak value unspecified - in the head at 4 cm; gradient magnetic field of 150 µT/cm
electric field strength 7.5 mV/cm peak value calculated - -

Exposure 2

Main characteristics
Frequency
Type
Exposure duration 20 min
Additional info direct current magnetic field
Exposure setup
Exposure source
Parameters

No parameters are specified for this exposure.

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

Low-field magnetic stimulation reduced immobility in the forced swim test, an antidepressant-like effect similar to that of standard antidepressants. Low-field magnetic stimulation did not alter locomotor activity or fear conditioning.
In conclusion, low-field magnetic stimulation has antidepressant-like effects in rats that seem unrelated to locomotor-activating or amnestic effects. These data raise the possibility that electromagnetic fields can affect the brain biology and might have physiologic consequences that offer novel approaches to therapy for psychiatric disorders.

Study character:

Study funded by

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