Endonuclease G is Upregulated and Required in Testicular Germ Cell Apoptosis after Exposure to 60 Hz at 200 μT

Several reports supported that continuous exposure to 60 Hz magnetic field (MF) induces testicular germ cell apoptosis in vivo. We recently evaluated durationand 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 μT for 24 hours a day for 2, 4, 6, or 8 weeks, and at 2, 20 or 200 μT for 24 hours a day for 8 weeks. To induce the apoptosis of testicular germ cell in mice, the minimum dose is 20 μT at continuous exposure to a 60 Hz MF for 8 weeks, and the minimum duration is 6 weeks at continuous exposure of 100 μT. Continuous exposure to a 60 Hz MF might affect durationand 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 μT at 60 Hz EMF (ICNIRP Guidelines, 2010). In the present study, we aimed to examine the expression of proand anti-apoptotic genes regulated by the continuous exposure to 60 Hz at 200 μT in Sprague-Dawley rats for 20 weeks. The continuous exposure to 60 Hz at 200 μT 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 μT for 20 weeks. We found that the message level of endonuclease G (EndoG) was greatly increased following the exposure to 60 Hz at 200 μT compared with sham control. These data suggested that 60 Hz magnetic field induced testicular germ cell apoptosis through mitochondrial protein Endo G.