Power Frequency Magnetic Fields Induce Autophagy In The Chinese Hamster Lung Cells

Object:With the development of electric power industry, exposure time and intensity of extremely low frequency magnetic fields (ELF MF) have been increased and public concern rasised on the effects of extremely low frequency magnetic fields exposure. Previous studies have indicated that ELF MF exposure induces cellular effects including decreased gap junction intercellular communication (GJIC), clusting of epidermal growth factor receptor (EGFR) and tumor necrosis factor receptor (TNFR), changes of gene and protein expression profile. Autophagy is the cellular process of bulk degradation and recycling of long-lived proteins, macromolecular aggregates, and damaged intracellular organelles, which prolongs survival for a short time under starvation conditions, and it also involves in neuromuscular diseases, aging and cancer. It has been showed that ionizing radiation such asΥ-rays; non-ionizing radiation such as ultraviolet rays can induce autophagy. In this study, we have studied the effects of ELF MF (50 Hz 0.4 mT) exposure on autophagy of Chinese hamster lung fibroblast cells (CHL). Methods:The CHL cells were cultured for 24 hours, and released in fresh media with exposure to 50 Hz 0.4 mT MF for 30 minutes,2 hours,6 hours,12 hours or 24 hours. Autophagy level induced by MF were detected by the following methods: detection of cell vacuoles by transmission electron microscopy, changes in intracellular GFP-LC3 labeled autophagic bodies highlights by confocal microscopy as well as the expression of LC3-Ⅱby Western Blot assay. Results:transmission electron microscopy (TEM) analyses showed that 50 Hz 0.4 mT MF induced an increase in intracellular vacuoles. In the CHL cells which high expressd GFP-LC3, the laser confocal microscope analyses showed that 50 Hz 0.4 mT MF exposure enhanced GFP-LC3 labeled autophagic bodies highlights, no statistically significance (P>0.05). Autophagy specific marker protein LC3-Ⅱexpression was increased after exposure to 50 Hz 0.4 mT MF (P> 0.05),30 minutes and 24 hours increasing trend is much more obvious. In addition, we found LC3-Ⅱexpression was increased after exposure 30 minutes to 50 Hz 0.4 mT MF (P<0.05) after add chloroquine to block autophagic bodies and lysosome fusion. Conclusion:These data indicate the 50 Hz 0.4 mT MF exposure may induce autophagy in CHL cells under the experimental conditions.