Bidirectional Effect of Repeated Exposure to Extremely Low-Frequency Electromagnetic Field (50 Hz) of 1 and 7 mT on Oxidative/Antioxidative Status in Rat’s Brain: The Prediction for the Vulnerability to Diseases

Abstract

Studies reported evidence for opposite effects of extremely low-frequency electromagnetic field (EMF): harmful, including the oxidative stress induction, and beneficial, such as the activation of antioxidant defense. People’s exposure to EMF is often repeated or prolonged, and it is important to consider the cumulative effect of such kind of exposure on the organism. If changes evoked by repeated exposure to EMF are permanent, responsiveness to other stress factors can be modified. The aims of our study were (1) to evaluate changes in the levels of oxidative stress and antioxidant defense markers in the prefrontal cortex of adult rats after repeated exposure to 1 and 7 mT EMF and (2) to assess whether repeated EMF exposure can modify oxidative/antioxidative status in response to other stress factors. Rats were exposed to EMF 1 h/day for 7 days, one, twice, or three times. After each exposure, 8-isoprostanes, protein carbonyl groups, and the total antioxidant capacity were assessed. Part of the animals, after EMF treatment, was exposed to another stress factor—open field. Results showed that repeated exposure changed the oxidative/antioxidative status depending on the intensity of the EMF and the number of exposures. 1 mT EMF created weak changes in the oxidative status in the brain; however, 7 mT EMF moved the balance to a clearly higher level. The changes in the oxidative status after 1 mT EMF were enough to reduce, and after 7 mT EMF to intensify oxidative processes in response to the next stress. We concluded that the organism might adapt to “weak” EMF, while “strong” EMF exceeds the adaptive capacity of the organism and sensitizes it to subsequent stress, and thus may modulate vulnerability to diseases. Our results also provide new insights into the possible therapeutic properties of the magnetic field, as 1 mT EMF appears to have a potentially protective impact on the brain.

Can Electromagnetic Fields Modulate Inflammation and Cell Death by Acting on the Immune System?

“…EMFs modulate the efficiency of cell death by altering the expression of calmodulin (CaM) and CaM-dependent proteins [42]. In summary, various in vitro and in vivo experimental studies highlighted here for their scientific quality [31][32][33][34][35][36][37][38][39][40][41][42] agree that the effect of ELF-MF (modulated or unmodulated) at the immune cell level depends on the oxidative status. Non-ionizing radiation in the 35-50 Hz frequency range and intensity of 1 to 7mT modulates antioxidant enzymes, increasing intracellular calcium levels, favouring therapy after cerebral vascular accidents, by modulating apoptosis caused by cytotoxic agents.…”

“…However, the lack of cumulative effects with repeated exposure cannot be guaranteed. On exposure to an EMF of field strength 7mT, cellular adaptation is insufficient to prevent harmful effects [34].…”

Open Questions on the Electromagnetic Field Contribution to the Risk of Neurodegenerative Diseases

“…Several studies have shown that EMF exposure modifies physiological and biochemical processes leading to immune cell activation [ 15 ], resulting in increased reactive oxygen species (ROS) formation, enhanced phagocytic activity, and increased cytokine release [ 23 , 51 ]. It was shown that EMF can cause mild oxidative stress (increase in ROS and changes in antioxidant levels) in many tissues of the body [ 16 , 52 , 53 ]. The increase in plasma concentration of pro-inflammatory cytokines and an elevation in blood parameters, such as white blood cells, lymphocytes, hemoglobin, and hematocrit levels in rats exposed to EMF (50 Hz, 7 mT, 24 h) were also demonstrated [ 15 , 54 ].…”

“…EMF treatment should be conducted under well-controlled conditions, supported by evidence of biological activity for EMF, which may lead to a positive or negative outcome depending on the exposure parameters. This is to ensure the safety of therapeutic treatments involving EMF, even more so when a direct action of an EMF occurring at one body location may have an indirect effect in another location [ 13 , 14 , 15 , 16 ]. According to published results, the most beneficial therapeutic cycle should include 10 to 14 daily treatments.…”

“…There have been articles indicating a relationship between the higher incidence of neurodegenerative diseases (NDD) and increased exposure to EMF [ 1 , 2 , 19 , 20 , 21 ]. Researchers are trying to define a mechanism that could explain this correlation by considering the contribution of oxidative stress, which is closely related to the occurrence of neurological diseases and may be developed under the influence of EMF, among other factors [ 16 , 22 , 23 ]. However, the key point is that it is not possible to simply split the impact of EMF exposure and multiple other interactive environmental pollutants (e.g., increases in background hormone-disruptive chemicals, air pollution, food additives, and petrochemicals from the motor and air transport), which all overlap and contribute to organism response.…”