Effects of static magnetic field exposure on plasma element levels in rat

Electromagnetic fields regulate iron metabolism in living organisms: A review of effects and mechanism

The emergence, evolution, and spread of life on Earth have all occurred in the geomagnetic field, and its extensive biological effects on living organisms have been documented. The charged characteristics of metal ions in biological fluids determine that they are affected by electromagnetic field forces, thus affecting life activities. Iron metabolism, as one of the important metal metabolic pathways, keeps iron absorption and excretion in a relatively balanced state, and this process is precisely and completely controlled. It is worth paying attention to how the iron metabolism process of living organisms is changed when exposed to electromagnetic fields. In this paper, the processes of iron absorption, storage and excretion in animals (mammals, fish, arthropods), plants and microorganisms exposed to electromagnetic field were summarized in detail as far as possible, in order to discover the regulation of iron metabolism by electromagnetic field. Studies and data on the effects of electromagnetic field exposure on iron metabolism in organisms show that exposure profiles vary widely across species and cell lines. This process involves a variety of factors, and the complexity of the results is not only related to the magnetic flux density/operating frequency/exposure time and the heterogeneity of the observed object. A systematic review of the biological regulation of iron metabolism by electromagnetic field exposure will not only contributes to a more comprehensive understanding of its biological effects and mechanism, but also is necessary to improve human awareness of the health related risks of electromagnetic field exposure.

Static magnetic field assisted thawing improves cryopreservation of mouse whole ovaries

Ovarian tissue cryopreservation is considered to be the only means to preserve fertility for prepubertal girls and women whose cancer treatment cannot be postponed. However, ovarian tissues are inevitably damaged by oxidative stress during cryopreservation, which threatens follicle survival and development, and thus affects female fertility. Therefore, reducing tissue oxidative stress injury is one of the major challenges to achieving efficient cryopreservation of ovarian tissues, especially for whole ovaries. Here, we proposed a new method to improve the antioxidant capacity of whole ovaries during cryopreservation, static magnetic field assisted thawing. The results demonstrated that the antioxidant capacity of the ovarian tissue was significantly improved by static magnetic field treatment. In addition, ovarian tissue allograft transplantation was carried out, which successfully achieved vascular regeneration and maintained follicular development. The findings of this study not only provide a new reference for the preservation of female fertility, but also is a major step forward in the cryopreservation of tissues and organs. It will have good application prospects in the field of assisted reproduction and cryo-biomedicine.

Evidence of the static magnetic field effects on bone-related diseases and bone cells

Static magnetic fields (SMFs), magnetic fields with constant intensity and orientation, have been extensively studied in the field of bone biology both fundamentally and clinically as a non-invasive physical factor. A large number of animal experiments and clinical studies have shown that SMFs have effective therapeutic effects on bone-related diseases such as non-healing fractures, bone non-union of bone implants, osteoporosis and osteoarthritis. The maintenance of bone health in adults depends on the basic functions of bone cells, such as bone formation by osteoblasts and bone resorption by osteoclasts. Numerous studies have revealed that SMFs can regulate the proliferation, differentiation, and function of bone tissue cells, including bone marrow mesenchymal stem cells (BMSCs), osteoblasts, bone marrow monocytes (BMMs), osteoclasts, and osteocytes. In this paper, the effects of SMFs on bone-related diseases and bone tissue cells are reviewed from both in vivo studies and in vitro studies, and the possible mechanisms are analyzed. In addition, some challenges that need to be further addressed in the research of SMF and bone are also discussed.

Effect of High Static Magnetic Field (2 T-12 T) Exposure on the Mineral Element Content in Mice

Relative stability of mineral elements in tissues is necessary for health. High static magnetic fields (HiSMFs) have been widely used in biomedical research and industry. However, the bioeffect of HiSMFs on animals is still unclear. In this study, we investigated the effects of HiSMF exposure on the levels of Mg, Fe, Zn, Ca, and Cu in the main organs of mice. The 8-week male C57BL/6 mice were treated by 2-4 T, 6-8 T, 10-12 T HiSMFs for 28 days. The mass fractions of Mg, Fe, Zn, Ca, and Cu in the liver, brain, kidney, and heart in mice were respectively measured by atomic absorption spectroscopy, and used to evaluate mineral element content in tissues. The 2-4 T HiSMF exposure has increased the Mg, Fe, and Ca content in the kidney, as well as the Zn content in the brain. The 6-8 T HiSMF exposure has increased the Zn level in the liver; Mg, Fe, and Ca levels in the kidney; and Fe level in the heart, while the Zn in the kidney, and Zn and Ca in the heart was decreased by 6-8 T HiSMF exposure. For the 10-12 T HiSMF exposure, the Mg in the kidney, the Fe in the liver and kidney, and Cu in the brain have been increased significantly. However, the Zn in the kidney and the Ca in the brain and the heart were reduced by 10-12 T HiSMF exposure. The HiSMF exposure for 28 days can alter the Mg, Fe, Zn, Ca, and Cu content in mice, and change with the different magnetic flux density of HiSMFs (2-4 T, 6-8 T, 10-12 T), elements, and organ types.

Effects of repetitive magnetic stimulation on the growth of primarily cultured hippocampus neurons in vitro and their expression of iron-containing enzymes

Background: The mechanism of action of repetitive transcranial magnetic stimulation (rTMS) involves the generation of neuronal and action potentials utilizing induced currents in time-varying magnetic fields. However, the long-lasting and effective biological impact of magnetic stimulation does not appear to be completely explained by the transient magnetic field pulses. In this context, we hypothesized magnetic stimulation may affect the expression of iron-containing enzymes in neurons, mediating the long-lasting biological effects associated with this stimulus. Methods: Primarily cultured hippocampus neurons from SD rats were used as the cell model in this study. These were randomly divided into control, sham, and magnetic stimulation groups to probe into the effect of the magnetic field directly. The latter group received 40%, 60%, and 100% maximal stimulator output Tesla (1.68, 2.52, and 4.2 T) with low-frequency rTMS (1 Hz). The expression of iron-containing enzymes (catalase and aconitase) and non-ferrous enzymes (protein kinase A) was measured with Western blotting and ELISA. Results: The survival rates of neurons in the 40%T and 60%T groups were significantly increased in comparison to the controls (P<0.05), while those in the 100%T group showed cell damage, with slightly disturbed neurite connections and decreased survival rate. Furthermore, catalase and aconitase expression was higher in all of the stimulated groups in comparison to controls (P<0.05). On the other hand, the expression of the iron-containing enzymes decreased in the 100%T group in comparison with the 40%T and 60%T groups (P<0.05). Meanwhile, the expression of protein kinase A was not significantly increased in the groups which underwent magnetic stimulation. Conclusion: rTMS may increase the expression of ferrous enzymes but does not have a strong effect on non-ferrous enzymes. Excessive intensity of magnetic stimulation may reduce neuronal survival rate and affect the expression of iron-containing enzymes. The mechanism underlying the lasting effect of rTMS may be related to the increase of ferriferous expression induced by magnetic stimulation, with a clear correlation with stimulation intensity.

Regulation of Osteoblast Differentiation and Iron Content in MC3T3-E1 Cells by Static Magnetic Field with Different Intensities

Many studies have indicated that static magnetic fields (SMFs) have positive effects on bone tissue, including bone formation and bone healing process. Evaluating the effects of SMFs on bone cell (especially osteoblast) function and exploring the mechanism, which is critical for understanding the possible risks or benefits from SMFs to the balance of bone remodeling. Iron and magnetic fields have the natural relationship, and iron is an essential element for normal bone metabolism. Iron overload or deficiency can cause severe bone disorders including osteoporosis. However, there are few reports regarding the role of iron in the regulation of bone formation under SMFs. In this study, hypomagnetic field (HyMF) of 500 nT, moderate SMF (MMF) of 0.2 T, and high SMF (HiMF) of 16 T were used to investigate how osteoblast (MC3T3-E1) responses to SMFs and iron metabolism of osteoblast under SMFs. The results showed that SMFs did not pose severe toxic effects on osteoblast growth. During cell proliferation, iron content of osteoblast MC3T3-E1 cells was decreased in HyMF, but was increased in MMF and HiMF after exposure for 48 h. Compared to untreated control (i.e., geomagnetic field, GMF), HyMF and MMF exerted deleterious effects on osteoblast differentiation by simultaneously retarding alkaline phosphatase (ALP) activity, mineralization and calcium deposition. However, when exposed to HiMF of 16 T, the differentiation potential showed the opposite tendency with enhanced mineralization. Iron level was increased in HyMF, constant in MMF and decreased in HiMF during cell differentiation. In addition, the mRNA expression of transferrin receptor 1 (TFR1) was promoted by HyMF but was inhibited by HiMF. At the same time, HiMF of 16 T and MMF of 0.2 T increased the expression of ferroportin 1 (FPN1). In conclusion, these results indicated that osteoblast differentiation can be regulated by altering the strength of the SMF, and iron is possibly involved in this process.

Static Magnetic Fields Modulate the Response of Different Oxidative Stress Markers in a Restraint Stress Model Animal

Stress is a state of vulnerable homeostasis that alters the physiological and behavioral responses. Stress induces oxidative damage in several organs including the brain, liver, kidney, stomach, and heart. Preliminary findings suggested that the magnetic stimulation could accelerate the healing processes and has been an effective complementary therapy in different pathologies. However, the mechanism of action of static magnetic fields (SMFs) is not well understood. In this study, we demonstrated the effects of static magnetic fields (0.8 mT) in a restraint stressed animal model, focusing on changes in different markers of oxidative damage. A significant increase in the plasma levels of nitric oxide (NO), malondialdehyde (MDA), and advanced oxidation protein products (AOPP), and a decrease in superoxide dismutase (SOD), glutathione (GSH), and glycation end products (AGEs) were observed in restraint stress model. Exposure to SMFs over 5 days (30, 60, and 240 min/day) caused a decrease in the NO, MDA, AGEs, and AOPP levels; in contrast, the SOD and GSH levels increased. The response to SMFs was time-dependent. Thus, we proposed that exposure to weak-intensity SMFs could offer a complementary therapy by attenuating oxidative stress. Our results provided a new perspective in health studies, particularly in the context of oxidative stress.

Effect of electromagnetic fields and antioxidants on the trace element content of rat teeth

The purpose of this study was to examine the possible effect of extremely low-frequency electromagnetic fields (ELF-EMFs), from a high-voltage source, on rat teeth in terms of changes in trace elements (TEs) and the effect of antioxidants (melatonin [MLT] and Ganoderma lucidum [GL]) in counteracting these effects. We used adult male Wistar albino rats with a mean weight of 250–300 g and divided the rats into eight groups. The groups were subjected to an ELF-EMF that was applied with a high-voltage line for 8 hours/day for 26 days (Groups I, II, and III) or 52 days (Groups V, VI, and VII). Groups IV and VIII were the 26- and 52-day control/sham groups, respectively. Groups II and VI were treated with GL, and Groups III and VII were treated with MLT. MLT and GL were administered daily based on the weight of the animals and appropriate standards. At the end of the study, the rats were euthanized, and their anterior teeth were extracted. The teeth were preserved in pure water before evaluating the major TEs. At the end of the study, TE concentrations (in mg/kg) were assessed in the control and test groups. Compared with Group V, statistically significant differences in the concentrations of zinc (Zn) and strontium (Sr) were found for Group VII (ELF-EMF + MLT) (P<0.05). Therefore, ELF-EMF exposure can change the content of certain TEs in teeth and, after administering MLT and GL, the values of some of the TEs return to normal.

Subchronic exposure to static magnetic field differently affects zinc and copper content in murine organs

PURPOSE

Static magnetic fields (SMF) have been widely used in research, medicine and industry. Since zinc and copper play an important role in biological systems, we studied the effects of the subchronic continuous SMF exposure on their distribution in murine tissues.

MATERIALS AND METHODS

For 30 days, mice were exposed to inhomogeneous, vertical, downward or upward oriented SMF of 1 mT averaged intensity with spatial gradient in vertical direction.

RESULTS

SMF decreased the amount of copper and zinc in liver. In brain, zinc levels were increased and copper levels were decreased. In spleen, zinc content was reduced, while copper amount remained unchanged.

CONCLUSIONS

Subchronic exposure to SMF differently affected copper and zinc content in examined organs, and the changes were more pronounced for the downward oriented field. The outcome could be attributed to the protective, rather than the harmful effect of SMF.

Alterations of mineral elements in osteoblast during differentiation under hypo, moderate and high static magnetic fields

Static magnetic fields (SMFs) can enhance the ability of bone formation by osteoblast and is a potential physical therapy to bone disorders and the maintenance of bone health. But, the mechanism is not clear yet. Certain mineral elements including macro and trace elements are essential for normal bone metabolism. Deficiency of these elements can cause severe bone disorders including osteoporosis. However, there are few reports regarding the role of mineral elements in the regulation of bone formation under SMFs. In this study, hypomagnetic field (HyMF) of 500 nT, moderate SMF (MMF) of 0.2 T, and high SMF (HiMF) of 16 T were used to investigate the effects of SMFs on mineral element (calcium, copper, iron, magnesium, manganese, and zinc) alteration of MC3T3-E1 cells during osteoblast mineralization. The results showed that osteoblasts in differentiation accumulated more mineral elements than non-differentiated cell cultures. Furthermore, HyMF reduced osteoblast differentiation but did not affect mineral elements levels compared with control of geomagnetic field. MMF decreased osteoblast differentiation with elevated iron content. HiMF enhanced osteoblast differentiation and increased all the mineral contents except copper. It is suggested that the altered potential of osteoblast differentiation under SMFs may partially due to the involvement of different mineral elements.