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Micronuclei in the blood and bone marrow cells of mice exposed to specific complex time-varying pulsed magnetic
Siddharth B Reddy1, Julie Weller, Dawn Desjardins-Holmes
1Lawson Health Research Institute, London, Ontario, Canada.
Abstract:
For 8 weeks, adult CD-1 male mice were continuously exposed to complex time-varying pulsed magnetic fields (PMF) generated in the horizontal direction by a set of square Helmholtz coils. The PMF were <1000 Hz and delivered at a peak flux density of 1 mT. Sham-exposed mice were kept in a similar exposure system without a PMF. Positive control animals exposed to 1 Gy gamma radiation were also included in the study. Blood samples were collected before (time 0) and at 2, 4, 6, and 8 weeks. All mice were euthanized at the end of 8 weeks and their bone marrow was collected. From each blood and bone marrow sample, smears were prepared on microscope slides, fixed in absolute methanol, air-dried, and stained with acridine orange. All slides were coded and examined using a fluorescence microscope. The extent of genotoxicity and cytotoxicity was assessed from the incidence of micronuclei (MN) and percent polychromatic erythrocytes (PCE) in the blood and bone marrow, respectively. The data indicated that both indices in PMF-exposed mice were not significantly different from those observed in sham-exposed animals. In contrast, positive control mice exhibited significantly increased MN, and decreased percentages of PCE in both tissues. Thus, the overall data suggested that 8 weeks of continuous exposure to PMF did not induce significantly increased genotoxicity and cytotoxicity in experimental mice. Further investigations are underway using other genotoxicity assays (comet assay, gamma-H2AX foci, and chromosomal aberrations) to assess genotoxicity following PMF exposure.
Insights
Pulsed magnetic fields (PMF) exposure for 8 weeks did not increase genotoxicity or cytotoxicity in mice. Micronuclei and polychromatic erythrocyte levels remained unchanged compared to sham-exposed controls, indicating safety.
Area of Science:
- Biophysics
- Toxicology
- Genetics
Background:
- Pulsed magnetic fields (PMF) are increasingly used, necessitating safety assessments.
- Understanding the potential genotoxic and cytotoxic effects of PMF is crucial for human health and safety.
Purpose of the Study:
- To evaluate the genotoxicity and cytotoxicity of continuous 8-week exposure to complex time-varying pulsed magnetic fields (PMF) in mice.
- To compare the effects of PMF exposure with sham exposure and a positive control (gamma radiation).
Main Methods:
- Adult male CD-1 mice were exposed to PMF (<1000 Hz, 1 mT peak flux density) or sham conditions for 8 weeks.
- Blood and bone marrow samples were analyzed for micronuclei (MN) incidence and polychromatic erythrocyte (PCE) percentage.
- Acridine orange staining and fluorescence microscopy were used for slide examination.
Main Results:
- PMF-exposed mice showed no significant difference in MN incidence or PCE percentage compared to sham-exposed mice.
- Positive control mice exposed to gamma radiation exhibited significantly increased MN and decreased PCE levels.
- The study found no significant genotoxic or cytotoxic effects from 8 weeks of PMF exposure.
Conclusions:
- Continuous 8-week exposure to the studied pulsed magnetic fields does not induce significant genotoxicity or cytotoxicity in mice.
- Further research using additional genotoxicity assays is recommended to comprehensively assess PMF safety.
