Study type: Medical/biological study (experimental study)

Combined effects of complex magnetic fields and agmatine for contextual fear learning deficits in rats med./bio.

Published in: Life Sci 2003; 72 (22): 2489-2498

Aim of study (acc. to author)

To examine possible additive effects of agmatine and theta-burst stimulation patterned complex magnetic field treatments for contextual fear learning.

Background/further details

52 rats were injected immediatly prior to a fear conditioning procedure with saline (0.9%) or agmatine (4 mg/kg). In a conditioning chamber rats were given three 2 sec electrical footshocks (0.5 mA) delivered at 60 sec intervals. 24 hours later rats were scored for defensive freezing when they returned to the conditioning chamber for 8 min. Immediatly after fear conditioning rats were placed for 30 min into an exposure cage or sham exposure cage.
The rats were trained on seven pairs of testing days over a period of two months. Additionally, the relationship between the intensity of the ambient geomagnetic field and amounts of contextual fear learning was examined three hours prior, during and after fear conditioning.



Exposure Parameters
Exposure 1: 60 Hz
Modulation type: pulsed
Exposure duration: 30 min

Exposure 1

Main characteristics
Frequency 60 Hz
Exposure duration 30 min
Modulation type pulsed
Additional info

initial pulse followed after 140 ms by a 100 Hz burst lasting for 255 ms and then beeing repeated

Exposure setup
Exposure source
Setup 3 pairs of solenoids positioned so that fields in x-, y- and z-axis were generated; fields combined to a rotating field with 2s orientation in each axis and 2 s field in all axes; rotation frequency 0.5 Hz
Sham exposure A sham exposure was conducted.
Measurand Value Type Method Mass Remarks
magnetic flux density 2 µT peak value measured - at 1 cm from any individual solenoid
magnetic flux density 1.5 µT peak value measured - at the center
magnetic flux density 200 µT peak value measured - in the corners

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

Exposed rats showed a significant decrease in freezing compared to sham-exposed rats. Agmatine-treated rats showed a significant decrease in freezing compared to saline-treated rats. The rats treated with agmatine and given post-conditioning exposures froze signifcantly less than all the other groups.
Only for the sham-exposed rats the amount of learned fear was correlated with the intensity of the ambient geomagnetic conditions during the interval of the conditioning sessions: increased ambient geomagnetic activity was associated with decreased fear learning.

Study character:

Study funded by

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