Effects of combined radiofrequency field exposure on amyloid-beta–induced cytotoxicity in HT22 mouse hippocampal neurones

Abstract

Alzheimer's disease (AD) is the most common progressive and irreversible neurodegenerative disease and it is caused by neuronal death in the brain. Recent studies have shown that non-ionizing radiofrequency (RF) radiation has some beneficial cognitive effects in animal models of AD. In this study, we examined the effect of combined RF radiation on amyloid-beta (Aβ)–induced cytotoxicity in HT22 rat hippocampal neurons. Treatment with Aβ suppressed HT22 cell proliferation in a concentration-dependent manner. RF exposure did not affect cell proliferation, and also had a marginal effect on Aβ-induced suppression of growth in HT22 cells. Cell cycle analysis showed that Aβ decreased the G1 fraction and increased the subG1 fraction, indicating increased apoptosis. Accordingly, Aβ increased the annexin V/propidium iodide (PI)–positive cell fraction and the degradation of poly (ADP ribose) polymerase and caspase-3 in HT22 cells. However, RF alone and the combination of Aβ and RF did not affect these events significantly. Aβ increased reactive oxygen species (ROS) generation, thereby suppressing cell proliferation. This was abrogated by N-acetylcysteine (NAC) treatment, indicating that Aβ-induced ROS generation is the main cause of suppression of proliferation. NAC also restored Aβ-induced annexin V/PI–positive cell populations. However, RF did not have a significant impact on these events. Finally, Aβ stimulated the ataxia telangiectasia and Rad3-related protein/checkpoint kinase 1 DNA single-strand breakage pathway, and enhanced beta-site amyloid precursor protein expression; RF had no effect on them. Taken together, our results demonstrate that RF exposure did not significantly affect the Aβ-induced decrease of cell proliferation, increase of ROS production, or induction of cell death in these cells.

Manmade Electromagnetic Fields and Oxidative Stress—Biological Effects and Consequences for Health

“…Similarly, no signs of inflammation, such as more iNOS or NO formation, were found in astrocytes after exposure to 1.8 GHz RF-EMF for 1–24 h (SAR: 1 W/kg) [ 95 ], although an acute increase in ROS after 20 min of exposure to modulated but not unmodulated 900 MHz RF-EMF was found [ 96 ]. On the other hand, in a mouse neuronal cell line, exposure to a 1.95 GHz RF-EMF (UMTS/3G signal) showed marginal effects on ROS formation and other parameters on its own, but differentially modulated signaling pathways and cytotoxicity when ROS formation was triggered by glutamate or β-amyloid [ 97 , 98 ].…”

Effects of Radiofrequency Electromagnetic Fields and Ionizing Radiation on Amyloid Precursor Protein Processing and Cell Death

“…However, we did not detect any induction of cell death or inhibition of clonogenic survival. Lee et al [21] also simultaneously exposed HT22 cells to two types of RF-EMF to evaluate their effects on cell death and beta amyloid treatment (4 W/kg SAR level; CDMA 2 W/kg + WCDMA 2 W/kg for 2 hours). Similarly, no effects were observed on cell proliferation, cell cycle distribution, and cell death as a result of RF-EMF in the absence or presence of Aβ treatment in the cells.…”

“…In one study, possible therapeutic beneficial effects were observed on βA-induced oxidative stress when primarycultured rat astrocytes were exposed to RF-EMFs for 24 hours [15]. However, some studies have also shown no changes in the neuronal cells after RF-EMF exposure [1,21].…”

Effects of 1950 MHz radiofrequency electromagnetic fields on Aβ processing in human neuroblastoma and mouse hippocampal neuronal cells

“…We used a radial transmission line (RTL) exposure system as an in vitro multifrequency radiation exposure system for this study [ 25 , 26 ]. A typical Code–Division Multiple Access (CDMA) signal at 837 MHz and a Wideband Code–Division Multiple Access (WCDMA) signal at 1950 MHz were applied to the RTL after amplification.…”

“…The 100-mm culture dishes were placed at 13.6 cm from the conical antenna, which was located at the center of the exposure chamber, and cells were then exposed to RF-EMF radiation in the culture dishes. This system has already been used in other published cellular studies [ 25 , 26 ]. The variation in RF-EMF exposures on different culture dishes was negligible, when multiple dishes were exposed at the same time: the variation in the average SAR values for WCDMA frequency was ~7.7% of the single dish exposure when three culture dishes were used, and ~2.0% when six dishes were exposed [ 25 , 26 ].…”