50-Hz magnetic field exposure influences DNA repair and mitochondrial DNA synthesis of distinct cell types in brain and kidney of adult mice.
Despite several recent investigations, the impact of whole-body magnetic field exposure on cell-type-specific alterations due to DNA damage and DNA repair remains unclear. In this pilot study adult mice were exposed to 50-Hz magnetic field (mean value 1.5 mT) for 8 weeks or left unexposed. Five minutes after ending exposure, the mice received [(3)H]thymidine and were killed 2 h later. Autoradiographs were prepared from paraffin sections of brains and kidneys for measuring unscheduled DNA synthesis and mitochondrial DNA synthesis, or in situ nick translation with DNA polymerase-I and [(3)H]dTTP. A significant (P<0.05) increase in both unscheduled DNA synthesis and in situ nick translation was only found for epithelial cells of the choroid plexus. Thus, these two independent methods indicate that nuclear DNA damage is produced by long-lasting and strong magnetic field exposure. The fact that only plexus epithelial cells were affected might point to possible effects of magnetic fields on iron transport across the blood-cerebrospinal fluid barrier, but the mechanisms are currently not understood. Mitochondrial DNA synthesis was exclusively increased in renal epithelial cells of distal convoluted tubules and collecting ducts, i.e., cells with a very high content of mitochondria, possibly indicating increased metabolic activity of these cells.
Schmitz
C
C
Department of Anatomy and Cell Biology, RWTH Aachen University, Pauwelsstrasse/Wendlingweg 2, 52057 Aachen, Germany.
Keller
E
E
Freuding
T
T
Silny
J
J
Korr
H
H
D000818:Animals; D001345:Autoradiography / Q000379:methods; D001921:Brain / Q000166:cytology; D002452:Cell Count / Q000379:methods; D002478:Cells, Cultured / Q000378:metabolism / Q000528:radiation effects*; D004260:DNA Repair / Q000528:radiation effects*; D004272:DNA, Mitochondrial / Q000096:biosynthesis / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D004574:Electromagnetic Fields; D020287:In Situ Nick-End Labeling / Q000379:methods; D007668:Kidney / Q000166:cytology*; D008297:Male; D051379:Mice; D008928:Mitochondria / Q000528:radiation effects; D013936:Thymidine / Q000378:metabolism; D014316:Tritium / Q000378:metabolism
D004272:DNA, Mitochondrial; D014316:Tritium; D013936:Thymidine