Suppression of Glucocorticoid Response in Stressed Mice Using 50 Hz Electric Field According to Immobilization Degree and Posture

Various studies on immobilized BALB/c mice to evaluate changes in hormone levels associated with stress responses have advanced the characterization of multiple aspects of the biological actions of extremely low-frequency (ELF) electric fields (EFs). In this study, we aimed to investigate the effect of mouse posture on its stress responses and evaluate the importance of adjusting the stress degree in the model. Mice were immobilized inside centrifuge tubes and exposed to an ELF EF generated between parallel plate electrodes. Blood was collected under anesthesia immediately after EF exposure, and plasma glucocorticoids were assayed. The inhibitory effects of EFs on glucocorticoid elevation by immobilization were reproduced regardless whether mice were in the abdominal or lateral recumbent position, for the EF vector delivered to mice through the sagittal or frontal plane. The effect of ELF EF was reproduced in moderately and mildly stressed mice but not in severely immobilized mice. Hence, adjusting the stress degree is critical to the reproducibility of the results for this model. We characterized the effects of ELF EF on homeostasis, including the stress response, and provided valuable information for the scientific evaluation of the biological risks and medical applications of ELF EF.

Stress-Reducing Effect of a 50 Hz Electric Field in Mice after Repeated Immobilizations, Electric Field Shields, and Polarization of the Electrodes

Simple Summary

With the increasing demand for electricity and electrical equipment, humans are routinely and unintentionally exposed to electric fields (EFs). Although no considerable adverse effects of EF exposure have been observed, slight physiological effects are known to occur. Additionally, there are methods and devices that expose subjects to EF for medical purposes. The mechanism of the biological effects of EF has not been identified, because the effects are not strong and may involve the physical properties of EFs, which are invisible and easily disturbed by obstacles. In a simple and short experiment using mice, we found that EF has an inhibitory effect on glucocorticoid (GC) responses. The experiment’s reproducibility was almost 100%. We tried to improve the understanding of the biological effects of EF by structuring our observations of the stress-reducing effects under different conditions in the system. We found that the inhibitory effect on the GC response was attenuated by EF shielding. We compared the effects of EF shielding between the head and abdomen, and found that the effects of EF were attenuated in both conditions, but might be more attenuated when the head was shielded. Thus, it appears that the area where the EF is distributed and the body part are important for the biological effects of EF. Two experiments with different conditions were performed. These results will help advance the current understanding of the effects of EF on stress systems.

Abstract

In BALB/c mice, immobilization-increased plasma glucocorticoid (GC) levels are suppressed by extremely low frequency (ELF) electric fields (EF). The aim of this study was to advance our understanding of the biological effects of ELF-EF, using its suppressive effect on the GC response. Mice were exposed to a 50 Hz EF of 10 kV/m via a parallel plate electrode and immobilized as needed. We examined the suppressive effect of ELF-EF on GC level change after repeated immobilizations, electrode polarization, and EF shielding of different portions of the mouse body parts. Additionally, bodyweight changes owing to stress and EF were examined. Immobilization-induced reduction in the plasma GC levels was reproduced in mice with stress and EF exposure, regardless of the stress episode numbers and electrode polarization. Furthermore, when the head of mice was shielded from the EF, the suppressive effect was possibly relatively lower than that when the abdomen was shielded. The bodyweight of the mice decreased for 3 days after immobilization before recovering; ELF-EF did not affect the bodyweight. Thus, to elicit the biological effects of the EF, not only the size of the area where the EF is distributed but also the area where the field is distributed should be important. The results also confirmed the stableness of the present experimental system, at least in terms of the stress-reducing effect. In addition, the restriction in this study caused weight loss, but ELF-EF was not considered to affect it. The results improve the understanding of the biological effect and medical applications of ELF-EF.

Evaluation of heart rate variability, blood pressure and lipid profile alterations from dual transceiver mobile phone radiation exposure

OBJECTIVES

Electromagnetic fields have been reported to alter electrical activities in the brain and heart. However, there is paucity of information on the potential functional alterations that magnetic fields from mobile phone could cause to the heart. This study investigated heart rate variability (HRV), blood pressure (BP) and lipid profile in Wistar rats exposed to electromagnetic field radiation from a dual transceiver mobile phone (DTrMP).

METHODS

Twenty-one male albino Wistar rats (140-180 g) were randomly assigned to two major groups positioned 5 m apart as follows: control: no phone (n=7) and treatment group (n=14) continuously exposed to electromagnetic field from Tecno T312 DTrMP 900/1800 MHz set in silence mode. Experimental treatment consisted in 10 min calls/day, directed to this device for a period of six weeks. Seven animals from the treatment group were allowed to recover for a period of two weeks after exposure. HRV, systolic, diastolic and mean arterial BP were noninvasively investigated, while serum lipid profile and heart tissue nitric oxide (NO) activities were determined using standard procedures.

RESULTS

There was significant (p<0.05) increase in systolic, diastolic, mean arterial BP and a decrease in HRV. Serum high density lipoproteins decreased, while total cholesterol, atherogenic indices, and heart NO levels increased significantly in the radiation exposed animals. The alterations observed in exposed animals remained unchanged even after the recovery period.

CONCLUSIONS

These results suggest that exposure to electromagnetic radiation from dual transceiver mobile phones could be a risk factor to increase in blood pressure.

Effects of Intermittent and Continuous Magnetic Fields on Trace Element Levels in Guinea Pigs

Electromagnetic fields (EMFs) can affect living cells due to biochemical changes, followed by changes in levels of trace elements in serum and different organs. This study focuses on the effect of whole body exposure to EMF, presented everywhere in our environment, and on the levels of trace elements in serum, femur, brain, kidney, and liver tissues. The analyses performed on 29 guinea pigs were divided into five groups. Guinea pigs were exposed to a magnetic field of 50 Hz of 1.5 mT. Groups A and B were exposed to the magnetic field for a period of 4 h/day continuously (4 h/day) for 4 and 7 days, respectively. Groups C and D were exposed to the magnetic field for a period of 4 h/day intermittently for 4 and 7 days, respectively. Group E animals were enrolled as control. Copper (Cu), zinc (Zn), calcium (Ca), and magnesium (Mg) levels were determined by atomic absorption spectroscopy in serum, femur, brain, kidney, and liver tissues in all guinea pigs. When compared to the control groups, the changes in the levels of Cu in serum samples, femur, and kidney tissues of the treated groups were statistically significant. The same was also true for the levels of Mg in the brain, kidney, and lung tissues. Our results suggest that in vivo continuous and intermittent exposure to EMF may cause disturbances in homeostasis of bioelements. These effects could be important risk factors for toxic effects of EMF, especially in relation to deterioration of bioelements.

Effects of subchronic extremely low-frequency electromagnetic field exposure on biochemical parameters in rats

The objective of the present study was to systematically determine the effects of 50 Hertz (Hz) magnetic fields (MFs) on biochemical parameters in rats. Sixty-four adult (5 weeks old, 140–165 g) male Sprague–Dawley rats were randomly divided into four groups: sham, 20 µTesla (µT), 100 µT, and 500 µT 50 Hz MF ( n = 16 in each group). The rats in the MF groups were exposed for 2 h daily for up to 4 weeks. Under these experimental conditions, body weight, organ coefficients, biochemical parameters (blood lipids, myocardial enzymes, liver function, and renal function) were measured. We found that 50 Hz MFs had no significant effects on growth or on the majority of blood biochemical parameters, with the exception of creatinine and cholesterol. However, the changes in creatinine and cholesterol were relatively small and unlikely to be clinically relevant.

Effects of electromagnetic fields on serum lipids in workers of a power plant

This study aimed to evaluate the effects of electromagnetic fields (EMF) exposure on levels of serum lipids in workers of an electric power plant. A cross-sectional study was carried out in an electric power plant in Zhejiang province, China, from August to September 2011. All participants were divided into two groups with high occupational EMF exposure and low occupational EMF exposure. The occupational EMF exposure included radiofrequency EMF and extremely low-frequency EMF. Occupational EMF exposure was associated with an increased level of low-density lipoprotein cholesterol (LDL-c; β = 0.17 mmol/L, P = 0.022). High EMF exposure group with longer employment duration, longer daily EMF exposure duration, and more mobile phone or electric fee per month had significantly higher levels of total cholesterol, LDL-c, or triglyceride than the corresponding reference group. However, significantly decreased level of high-density lipoprotein cholesterol was only observed in high EMF exposure group with more mobile phone fee per month. Similar results were also found in 544 participants with available data of serum lipids in 2010. The findings showed that chronic EMF exposure was associated with the change of serum lipid levels. EMF exposure might modulate the process of lipid metabolism.

Effects of extremely low frequency electromagnetic fields on human fetal scleral fibroblasts

This study investigated the effects of extremely low frequency electromagnetic fields (ELF-EMFs) on human fetal scleral fibroblasts (HFSFs). HFSFs were subjected to 50 Hz artificial ELF-EMFs generated by Helmholtz coils with 0.1, 0.2, 0.5, and 1.0 mT field intensities for 6 to 48 h. The viability and factors involved in scleral structuring of HFSFs were determined. The growth rate of HFSFs significantly decreased after only 24 h of exposure to ELF-EMFs (0.2 mT). The messenger RNA (mRNA) expression of collagen type I (COL1A1) decreased and expression of matrix metalloproteinase-2 (MMP-2) increased significantly. There was a decrease in tissue inhibitor of MMP-2 mRNA levels between treated and control cells only at the 1.0 mT intensity level. Transforming growth factor beta-2 mRNA increased in exposed cells, and, simultaneously, fibroblast growth factor-2 mRNA levels decreased. The protein expressions of COL1A1 and MMP-2 were also significantly altered subsequent to exposure (p < 0.05). This study shows that ELF-EMFs had biological effects on HFSFs and could cause abnormality in scleral collagen.

Effect of 50 Hz electric field in diacylglycerol acyltransferase mRNA expression level and plasma concentration of triacylglycerol, free fatty acid, phospholipid and total cholesterol

Background

The effects of exposure to a 50 Hz electric field (EF) on plasma level of triacylglycerol, free fatty acids, total cholesterol and phospholipid and mRNA expression level of diacylglycerol acyltransferase (DGAT) 1 and 2 in liver and intestines from C57BL/6 J mice were studied.

Methods

The test was based on comparison between mice post treated with 50 Hz EF of 45 kV/m intensity for 30 min per day for 11 days or without EF. DGATs mRNA expression was analyzed by real-time quantitative polymerase chain reaction.

Results

There was no difference in the gene expression level of DGAT1 in liver and intestines. The DGAT2 gene expression level in liver derived from mice treated with EF was significantly lower than those in the control (P < 0.001). Both plasma total cholesterol (P < 0.01) and phospholipid (P < 0.05) in the group exposed to EF were lower than those in the control, but there was no difference in triacylglycerol or free fatty acid levels.

Conclusion

Exposure to 50 Hz EF decrease the plasma levels of total cholesterol and phospholipids, and downregulated DGAT2 mRNA expression in liver. The mechanisms for the effects of EF on lipid metabolism are not well understand yet, but altered DGAT2 activity may be involved.