Study type: Medical/biological study (experimental study)

Threshold of pain in chronic magnetic field- (50 Hz, 17.9 microT) exposed rats: effect of sucrose ingestion. med./bio.

Published in: Electromagn Biol Med 2008; 27 (3): 254-265

Aim of study (acc. to author)

To study the effects of acute sucrose ingestion on threshold of pain in chronic extremely low frequency magnetic fields exposed rats and whether sucrose ingestion potentiates the analgesia of magnetic field exposure.

Background/further details

Both magnetic field exposure and sucrose ingestion can produce opioid mediated analgesia independently.
Male rats (n=6) were studied in four experimental conditions: 1) sham exposure (day 1-7), 2) control sucrose-ingestion (day 9), 3) magnetic field exposure (day 10-16), 4) magnetic field exposure + sucrose-ingestion (day 17). Nociceptive behavior was studied by 21 noxious electrical stimuli during 7 sessions (0, 5, 10, 15, 30, 45 and 60 min).

Endpoint

Exposure

Exposure Parameters
Exposure 1: 50 Hz
Exposure duration: continuous for 8 h/day for 7 days

Exposure 1

Main characteristics
Frequency 50 Hz
Type
Exposure duration continuous for 8 h/day for 7 days
Exposure setup
Exposure source
Setup two outer coils with 18 turns each, two inner coils with 8 turns each; 38 cm x 24 cm x 15 cm polypropylene cage placed in the center of the coils system
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 17.9 µT effective value - - -

Reference articles

  • Kirschvink JL (1992): Uniform magnetic fields and double-wrapped coil systems: improved techniques for the design of bioelectromagnetic experiments.

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

Group 1) vs. 3): The basal threshold of pain (at 0 min) did not vary between the control group and the magnetic field exposed rats. During session 2 to 7, the pain thresholds did not vary in the control group but increased in exposed rats. The pain thresholds of exposed rats were elevated compared to the control group.
Group 2) vs. 4): Control sucrose group vs. magnetic field sucrose group elevated the threshold of tail response in control rats but not in the exposure group. The thresholds of vocalization during and after stimulus were more elevated in control rats than in exposed rats.
The results suggest that the magnetic field exposure for 7 days did not affect the basal thresholds of pain, but it increased stress (repeated presentation of noxious stimuli) induced analgesia. Ingestion of sucrose by the magnetic field exposed rats did not potentiate analgesia. It attenuated the stress induced analgesia. Opiod mediated behaviors may be compromised under chronic magnetic field exposure.

Study character:

Study funded by

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