この研究は、著者の以前の報告（50Hz磁界（MF）への事前の24時間ばく露により、メナジオン誘導性DNA損傷が変化する）を前提に、MFが誘導したDNA損傷の変化（必ず生じると著者は仮定している）が、ばく露を受けた細胞の子孫細胞にゲノム不安定性を引き起こすか否かを調べた。ヒト神経芽腫細胞SH-SY5YにMF（ヘルムホルツコイル；50 Hz、100 μT）の24時間ばく露を与えた後、メナジオンに3時間ばく露した。その結果、MFばく露群では、ばく露から8および15日後に、小核出現頻度が上昇した；その他のMFの遅発性影響として、ばく露から8日後のミトコンドリア活性上昇、15日後の活性酸素種産生および脂質過酸化の増加が見られた；一方、酸化過程への影響はMFばく露直後に見られた､と報告している。
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To examine the cellular changes occurring during the first 24 hours of exposure to a 50 Hz-magnetic field and to analyze whether the induced changes can lead to genomic instability in the progeny of the exposed cells.
In previous studies (Markkanen et al. 2008, Luukkonen et al. 2011), the authors found that a pre-exposure to 50 Hz-magnetic fields before a menadione treatment alters the cellular response and increases the genotoxicity. Menadione is a free radical-producing DNA damaging agent.
Cells were exposed or sham exposed to a magnetic field for 24 hours. Afterwards, they were incubated without or with menadione treatment for three hours (different concentrations of menadione were used). Micronucleus frequency was determined 11 or 18 days after the menadione treatment. All other assays were performed immediately after the magnetic field exposure/sham exposure, immediately after the menadione treatment or 8 or 15 days after the menadione treatment.
ばく露時間: continuous for 24 hours
|ばく露時間||continuous for 24 hours|
|ばく露装置の詳細||a pair of coils (34 x 46 cm) was placed in an incubator with 5 % CO2 and 37°C, distance between the coils 22 cm, coils generated a horizontal magnetic field, cells were positioned at the center of the coils for ensuring a uniform magnetic flux density|
|Sham exposure||A sham exposure was conducted.|
In exposed cell cultures (after 11 and 18 days), the levels of micronuclei were significantly increased compared to the sham exposed cell cultures. Additionally, the mitochondrial activity (after 8 days), the production of reactive oxygen species (after 15 days) and the lipid peroxidation (after 15 days) were significantly increased in the exposed cultures when compared to sham exposed cultures. Immediately after the exposure, the level of reactive oxygen species was significantly increased in comparison to sham exposed cell cultures while the level of reduced glutathione was significantly decreased.
The data indicate that exposure to a 50 Hz-magnetic field could disturb the oxidative/antioxidative balance immediately after the exposure and indicate an induction of genomic instability in the progeny of exposed cells.