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Medical/biological study (experimental study)

Gene expression in the mammary gland tissue of female Fischer 344 and Lewis rats after magnetic field exposure (50 Hz, 100 muT) for 2 weeks.

Published in: Int J Radiat Biol 2012; 88 (5): 425-429

Aim of study (acc. to author)

To elucidate magnetic field effect-associated candidate genes, gene expression in magnetic field-susceptible Fischer 344 rats and magnetic field-insensitive Lewis rats was compared (to explain the different strain sensitivity to magnetic field exposure as shown in a previous studies: Fedrowitz and Löscher 2008 and Fedrowitz and Löscher 2005).
Background/further details: Five rats per group at an age of 52 days were exposed and five rats per group were sham exposed (in total n=20). A total of four arrays were performed with the pooled RNA of sham exposed or exposed Fischer 344 rats and Lewis rats.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 50 Hz
Exposure duration: continuous for 7 days/week during 2 weeks
Exposure 1
Main characteristics
Frequency 50 Hz
Type
Polarization
Exposure duration continuous for 7 days/week during 2 weeks
Exposure setup
Exposure source
Setup rats were exposed in their cages (5 rats per cage) located in the exposure chambers to a horizontally polarized magnetic field
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 100 µT effective value measured - -
Additional parameter details
stray field from the coils for sham exposure: B = 0.1 µT measured and calculated
Reference articles
  • Fedrowitz M et al. (2005): Power frequency magnetic fields increase cell proliferation in the mammary gland of female Fischer 344 rats but not various other rat strains or substrains.
  • Fedrowitz M et al. (2002): Magnetic field exposure increases cell proliferation but does not affect melatonin levels in the mammary gland of female Sprague Dawley rats.
Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

The analysis of gene expression in the mammary gland tissue revealed that altogether only 23 transcripts out of 31,100 probe sets were altered after magnetic field exposure. In the breast tissue of Lewis rats, nine genes were upregulated, whereas eight upregulations and six downregulations of gene expressions were apparent in magnetic field exposed Fischer 344 rats.
A remarkably decreased alpha-amylase gene expression, downregulations in carbonic anhydrase 6 and lactoperoxidase (both relevant for pH regulation), and an upregulated gene expression of cystatin E/M (a tumor suppressor) were found in exposed Fischer 344 rats, but not in Lewis rats.
In conclusion, the magnetic field exposed breast tissue of Fischer 344 rats showed alterations in gene expression, which were absent in Lewis rats and may therefore be involved in the magnetic field-susceptibility of Fischer 344 rats. Alpha-amylase might serve as a promising target to study magnetic field effects.
Study character:

Study funded by

  • Deutsche Forschungsgemeinschaft (DFG; German Research Foundation)

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