Effects of extremely low-frequency electric fields at different intensities and exposure durations on mismatch negativity

The protective role of 5-hydroxy-1,4-naphthoquinone against the harmful effects of 50 Hz electric field in rat lung tissue

There is strong scientific evidence that the electric field is harmful to life. Exposure to an electric field (EF) can cause lung toxicity and respiratory disorders. In addition, the electric field has been shown to cause tissue damage through inflammation and apoptosis. Juglone (JUG) is one of the powerful antioxidants with anti-apoptotic and anti-inflammatory, various pharmacological properties in the biological system. In this study, we evaluated the efficacy of JUG against the potential adverse effects of electric field on the lung. Twenty-four Wistar albino rats were randomly divided into three groups; control group (Cont), EF group, and EF exposure+JUG-treated group (EJUG). After routine histological procedures, sections stained with hematoxylin-eosin (H&E) showed significant changes in lung tissues in the EF group compared to the Cont group. Significant protective effects were observed in the building volumes and histopathology in the EJUG group. Our immunohistochemical and gene expression results increased the expression of caspase-3 and tumor necrosis factor alpha (TNF-α) in the EF group (p < 0.05). Juglon increased cytokine signal suppressor (SOCS) expression (p < 0.001). These findings were consistent with the antioxidant effect of JUG treatment. We reasoned that exposure to EF damaged rat lung tissues and administration of JUG alleviated the complications caused by 50 Hz EF.

The effects of acute and chronic exposure to 900 MHz radiofrequency radiation on auditory brainstem response in adult rats

The aim of this study was to determine the effects of short and long-term RFR exposure on ABR by evaluating lipid peroxidation and antioxidant status in adult rats. Sixty male albino Wistar rats were randomly divided into four groups. S1:1 week sham, S10:10 weeks sham, E1:1 week RFR, E10:10 weeks RFR. Experimental group rats were exposed to RFR 2 h/day, 5 days/week during the test period. Sham rats were kept in the same conditions without RFR. After the experiment, ABRs were recorded from the mastoids of rats using tone burst acoustic stimuli. Biochemical investigations in rat brain and ultrastructural analysis in temporal cortex were performed. ABR wave I latency prolonged in E1-group and shortened in E10-group compared to their shams. TBARS level increased in E1-group, decreased in E10-group, on the contrary, SOD and CAT activities and GSH level decreased in E1-group, increased in E10-group compared to their sham groups. Edema was present in the neuron and astrocyte cytoplasms and astrocyte end-feet in both E1 and E10 groups. Our results suggest that 900 MHz RFR may have negative effects on the auditory system in acute exposure and no adverse effects in chronic exposure without weekends.

Exposure to Static and Extremely-Low Frequency Electromagnetic Fields and Cellular Free Radicals

This paper summarizes studies on changes in cellular free radical activities from exposure to static and extremely-low frequency (ELF) electromagnetic fields (EMF), particularly magnetic fields. Changes in free radical activities, including levels of cellular reactive oxygen (ROS)/nitrogen (RNS) species and endogenous antioxidant enzymes and compounds that maintain physiological free radical concentrations in cells, is one of the most consistent effects of EMF exposure. These changes have been reported to affect many physiological functions such as DNA damage; immune response; inflammatory response; cell proliferation and differentiation; wound healing; neural electrical activities; and behavior. An important consideration is the effects of EMF-induced changes in free radicals on cell proliferation and differentiation. These cellular processes could affect cancer development and proper growth and development in organisms. On the other hand, they could cause selective killing of cancer cells, for instance, via the generation of the highly cytotoxic hydroxyl free radical by the Fenton Reaction. This provides a possibility of using these electromagnetic fields as a non-invasive and low side-effect cancer therapy. Static- and ELF-EMF probably play important roles in the evolution of living organisms. They are cues used in many critical survival functions, such as foraging, migration, and reproduction. Living organisms can detect and respond immediately to low environmental levels of these fields. Free radical processes are involved in some of these mechanisms. At this time, there is no credible hypothesis or mechanism that can adequately explain all the observed effects of static- and ELF-EMF on free radical processes. We are actually at the impasse that there are more questions than answers.

A comparative study on influences of static electric field and power frequency electric field on cognition in mice

Recently, electromagnetic fields around ultra-high voltage transmission lines have received considerable attentions for their potential biological effects. This study aimed to investigate the effects of static electric field (SEF) and power frequency electric field (PFEF) on cognition. Mice were exposed to SEF and PFEF with the same strength (35 kV/m) for 49 days, respectively. Behaviors in Morris water maze test and amino acid neurotransmitter levels in hippocampus were examined during exposure. Results indicated that the exposure of 35 kV/m SEF would not cause significant influences on learning and memory ability in mice, while the exposure of 35 kV/m PFEF would cause significant positive effects on learning and memory ability in mice on day 33. This difference in effects from SEF and PFEF on cognition was possibly induced by the difference in the degree of molecular polarization and ion migration in organisms under exposure of two kinds of electric fields with different frequency.

Characterization of the suppressive effects of extremely-low-frequency electric fields on a stress-induced increase in the plasma glucocorticoid level in mice

We recently suggested that an increase in the plasma glucocorticoid (GC) level in immobilized mice is suppressed by a 50-Hz electric field (EF) in an EF strength-dependent manner. The present study aimed to assess the anti-stress effect of EFs in three scenarios: exposure to an EF of either 50 or 60 Hz, which are the standard power frequencies in most regions; varying levels of environmental brightness during EF exposure; complete or partial shielding of the mouse from the EF. We compared the GC levels and blood parameters among control, EF-alone, immobilization-alone, and co-treatment groups. There was no difference between EFs of 50 and 60 Hz in terms of the suppression of the immobilization-induced increase in GC, that is, the anti-stress effect upon EF exposure. Examination of the effects of three environmental illuminance levels, 0, 200, and 490 lux, revealed that the effect of the EF was influenced by environmental illuminance. Shielding of the mice from the EF by wrapping the animals with an electrically conductive sheet inhibited the EF effect, which showed a negative correlation with the area shielded. Hence, environmental illuminance and the body area exposed to the EF might influence the effects of an EF on stress-induced increases in plasma GC levels in mice. Because stress plays an important role in the onset and progression of various diseases, these findings may have broad implications for understanding the efficacy of EFs in health. Bioelectromagnetics. 39:516-528, 2018 © 2018 Wiley Periodicals, Inc.

Duration-dependent effect of exposure to static electric field on learning and memory ability in mice

With the rapid development of ultra-high-voltage direct-current (UHVDC) transmission, the strength of environmental static electric field (SEF) around UHVDC transmission lines increased substantially, which has aroused widely public attention on the potential health effects of SEF. In this study, the effect of SEF exposure on learning and memory ability was investigated. Institute of Cancer Research mice were exposed to 56.3 kV/m SEF for a short term (7 days) or long term (49 days). Behaviors in the Morris water maze (MWM) test, hippocampal neurotransmitter contents, and oxidative stress indicators were examined. Results showed that short-term SEF exposure significantly prolonged escape latency and decreased the number of platform-site crossovers, as well as decreased the time spent in the target quadrant in the MWM test. Meanwhile, serotonin level and the ratio of glutamate level to γ-aminobutyric acid level changed significantly. Besides, malondialdehyde content and glutathione peroxidase activity increased significantly, while superoxide dismutase activity decreased significantly. After long-term SEF exposure, all indices above showed no significant differences between the SEF and sham exposure groups. These data indicated that short-term exposure to 56.3 kV/m SEF could cause abnormal neurotransmitter levels and oxidative stress in the hippocampus, which led to the decline in learning and memory ability. Under the condition of long-term exposure, the SEF-induced disturbances in neurotransmitter contents and redox balance were offset by the compensatory responses of mice, and thus, the learning and memory ability returned to normal level. The temporary and reversible decline in learning and memory ability was only a common biological effect of SEF rather than a health hazard.

Configuration-dependent variability of the effect of an electric field on the plasma glucocorticoid level in immobilized mice

We recently reported that an immobilization stress-induced increase in glucocorticoid (GC) level was suppressed in mice exposed to an electric field (EF) of 50 Hz in a kV/m-dependent manner. In this study, we investigated the reproducibility of the suppressive effect induced by EF exposure by varying the voltage and distance between the electrodes (0.5 kV/50 mm, 1 kV/100 mm, 2 kV/200 mm) and comparing the effects on the plasma GC level. In addition, the effect of mice being in contact with the lower electrode or not was compared at 1 kV/100 mm. Immobilization-induced GC levels were significantly decreased in mice exposed to an EF at 1 kV/100 mm for 60 min (P < 0.01), but not in mice exposed to 0.5 kV/50 mm or 2 kV/200 mm. Furthermore, the suppressive effect of the 1 kV/100 mm EF was canceled when a polypropylene sheet (0.1 mm thick) was placed between the animal and lower electrode. Our findings corroborated that an EF of 10 kV/m inhibits stress-induced changes in the endocrine system in mice and demonstrated that this effect depends on the configuration of the EF exposure system, even when the EF strength remains the same. Bioelectromagnetics. 38:265-271, 2017. © 2017 Wiley Periodicals, Inc.

Effects of pre- and postnatal exposure to extremely low-frequency electric fields on mismatch negativity component of the auditory event-related potentials: Relation to oxidative stress

In our previous study, the developmental effects of extremely low-frequency electric fields (ELF-EF) on visual and somatosensory evoked potentials in adult rats were studied. There is no study so far examining the effects of 50 Hz electric field (EF) on mismatch negativity (MMN) recordings after exposure of rats during development. Therefore, our present study aimed to investigate MMN and oxidative brain damage in rats exposed to EF (12 kV/m, 1 h/day). Rats were divided into four groups, namely control (C), prenatal (Pr), postnatal (Po), and prenatal+postnatal (PP). Pregnant rats of Pr and PP groups were exposed to EF during pregnancy. Following birth, rats of PP and Po groups were exposed to EF for three months. After exposure to EF, MMN was recorded by electrodes positioned stereotaxically to the surface of the dura, and then brain tissues were removed for histological and biochemical analyses. The MMN amplitude was higher to deviant tones than to standard tones. It was decreased in all experimental groups compared with the C group. 4-Hydroxy-2-nonenal (4-HNE) levels were significantly increased in the Po group with respect to the C group, whereas they were significantly decreased in the PP group compared with Pr and Po groups. Protein carbonyl levels were significantly decreased in the PP group compared with C, Pr, and Po groups. EF decreased MMN amplitudes were possibly induced by lipid peroxidation.