Endonuclease G is Upregulated and Required in Testicular Germ Cell Apoptosis after Exposure to 60 Hz at 200 μT |
Sungman Park1, Min-Woo Kim2, Ji-Hoon Kim1, Yena Lee1, Min Soo Kim1, Yong-Jun Lee1, Young-Jin Kim1, Hee-Sung Kim1, Yoon-Won Kim1 |
1Institute of Medical Science, School of Medicine, Hallym University 2Department of Microbiology, School of Medicine, Hallym University |
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Abstract |
Several reports supported that continuous exposure to 60 Hz magnetic field (MF) induces testicular germ cell apoptosis in vivo. We recently evaluated duration- and dose-dependent effects of continuous exposure to a 60 Hz MF on the testes in mice. BALB/c male mice were exposed to a 60 Hz MF at $100{mu}T$ for 24 hours a day for 2, 4, 6, or 8 weeks, and at 2, 20 or $200{mu}T$ for 24 hours a day for 8 weeks. To induce the apoptosis of testicular germ cell in mice, the minimum dose is $20{mu}T$ at continuous exposure to a 60 Hz MF for 8 weeks, and the minimum duration is 6 weeks at continuous exposure of $100{mu}T$. Continuous exposure to a 60 Hz MF might affect duration- and dose-dependent biological processes including apoptotic cell death and spermatogenesis in the male reproductive system of mice. The safety guideline of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) indicates that the permissible maximum magnetic flux density for general public exposure is $200{mu}T$ at 60 Hz EMF (ICNIRP Guidelines, 2010). In the present study, we aimed to examine the expression of pro- and anti-apoptotic genes regulated by the continuous exposure to 60 Hz at $200{mu}T$ in Sprague-Dawley rats for 20 weeks. The continuous exposure to 60 Hz at $200{mu}T$ does not affect the body and testicular weight in rats. However, exposure to 60 Hz MF significantly affects testicular germ cell apoptosis and sperm count. Further, the apoptosis-related gene was scrutinized after exposure to 60 Hz at $200{mu}T$ for 20 weeks. We found that the message level of endonuclease G (EndoG) was greatly increased following the exposure to 60 Hz at $200{mu}T$ compared with sham control. These data suggested that 60 Hz magnetic field induced testicular germ cell apoptosis through mitochondrial protein Endo G. |
Key words:
60 Hz Magnetic Field, Apoptosis, Endonuclease G, Reproductive Function, Testicular Germ Cell |
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