Exposure to inhomogeneous static magnetic field ceases mechanical allodynia in neuropathic pain in mice

The Analgesic Effects of Static Magnetic Fields

Pain is one of the most common reasons why people seek medical care, which is related to most disease states. Magnetic fields (MFs) can be applied locally to specific parts of human bodies with high penetration and temporal control, which have a long-debated history in folk therapy. The purpose of this review is to collect and analyze experimental data about the analgesic effects of static magnetic fields (SMFs) so that we can have a scientific understanding regarding this topic. We collected 28 studies (25 English and 3 Chinese papers) with proper sham controls that investigated the effects of SMFs on pain relief in humans or mice. We found that 64% of the human studies and all mice studies in the literature showed positive analgesic effects of SMFs, which are related to factors including SMF intensity, treatment time, and pain types. Higher intensity and/or longer treatment time, as well as some specific pain types, may have better pain relief effects. Initial mechanistic studies indicated that membrane receptors, such as capsaicin receptor VR1/TRPV1, opioid receptors, and P2X3 receptors, might be involved. By describing experimental evidence and analysis, we found that SMFs actually hold considerable promise for managing some specific types of pain if proper SMF parameters are used. More studies comprehensively evaluating the parameters of SMF and its corresponding analgesic effects on different pain types, as well as the underlying molecular mechanisms, will be necessary to further validate its therapeutic potential in pain management in the future. Bioelectromagnetics. 00:00-00, 2021. © 2021 Bioelectromagnetics Society.

Influence of inhomogeneous static magnetic field-exposure on patients with erosive gastritis: a randomized, self- and placebo-controlled, double-blind, single centre, pilot study

This pilot study was devoted to the effect of static magnetic field (SMF)-exposure on erosive gastritis. The randomized, self- and placebo-controlled, double-blind, pilot study included 16 patients of the 2nd Department of Internal Medicine, Semmelweis University diagnosed with erosive gastritis. The instrumental analysis followed a qualitative (pre-intervention) assessment of the symptoms by the patient: lower heartburn (in the ventricle), upper heartburn (in the oesophagus), epigastric pain, regurgitation, bloating and dry cough. Medical diagnosis included a double-line upper panendoscopy followed by 30 min local inhomogeneous SMF-exposure intervention at the lower sternal region over the stomach with peak-to-peak magnetic induction of 3 mT and 30 mT m(-1) gradient at the target site. A qualitative (post-intervention) assessment of the same symptoms closed the examination. Sham- or SMF-exposure was used in a double-blind manner. The authors succeeded in justifying the clinically and statistically significant beneficial effect of the SMF- over sham-exposure on the symptoms of erosive gastritis, the average effect of inhibition was 56% by p = 0.001, n = 42 + 96. This pilot study was aimed to encourage gastroenterologists to test local, inhomogeneous SMF-exposure on erosive gastritis patients, so this intervention may become an evidence-based alternative or complementary method in the clinical use especially in cases when conventional therapy options are contraindicated.

The effect of whole-body, repetitive, inhomogeneous static magnetic field-exposure on the symptoms of experimental autoimmune encephalomyelitis in mice

Experimental autoimmune encephalomyelitis (EAE) is a model for human multiple sclerosis (MS) in rodents. Static magnetic field (SMF)-exposure was shown to be beneficial in specific cases of inflammatory background, where it suppresses symptoms. The null-hypothesis was that animals with induced EAE exposed to SMF would show different seriousness of symptoms, than those in the sham-exposed control group. Three replicated series of repetitive, 30 min/day whole-body exposure to SMF with 477 mT peak-to-peak magnetic induction and 48 T/m lateral induction gradient was tested on female CSJLF1 mice with a mild, mouse spinal cord homogenate emulsion-induced EAE. Conventional scores of the animal response to EAE were compared between sham- and SMF-exposed groups of animals. Following pilot test we used 18 animals per group. Primary outcome measure was the daily group average of standard EAE scores. Results show that SMF-exposure has a strong, reproducible, and significantly beneficial effect up to 51.82% (p<0.001) over sham-exposure on the symptoms of EAE in the course of the 25 days of the experiment. This study aimed to build experimental research foundation for a later therapy option by applying SMF-exposure in the clinical management of MS.

In vitro analysis of the anti-inflammatory effect of inhomogeneous static magnetic field-exposure on human macrophages and lymphocytes

The effect of inhomogeneous static magnetic field (SMF)-exposure on the production of different cytokines from human peripheral blood mononuclear cells (PMBC), i.e., lymphocytes and macrophages, was tested in vitro. Some cultures were activated with lipopolysaccharide (LPS) at time point −3 h and were either left alone (positive control) or exposed to SMF continuously from 0 until 6, 18, or 24 h. The secretion of interleukin IL-6, IL-8, tumor necrosis factor TNF-α, and IL-10 was tested by ELISA. SMF-exposure caused visible morphological changes on macrophages as well as on lymphocytes, and also seemed to be toxic to lymphocytes ([36.58; 41.52]%, 0.308≤p≤0.444), but not to macrophages (<1.43%, p≥0.987). Analysis of concentrations showed a significantly reduced production of pro-inflammatory cytokines IL-6, IL-8, and TNF-α from macrophages compared to negative control ([56.78; 87.52]%, p = 0.031) and IL-6 compared to positive control ([45.15; 56.03]%, p = 0.035). The production of anti-inflammatory cytokine IL-10 from macrophages and from lymphocytes was enhanced compared to negative control, significantly from lymphocytes ([−183.62; −28.75]%, p = 0.042). The secretion of IL-6 from lymphocytes was significantly decreased compared to positive control ([−115.15; −26.84]%, p = 0.039). This massive in vitro evidence supports the hypotheses that SMF-exposure (i) is harmful to lymphocytes in itself, (ii) suppresses the release of pro-inflammatory cytokines IL-6, IL-8, and TNF-α, and (iii) assists the production of anti-inflammatory cytokine IL-10; thus providing a background mechanism of the earlier in vivo demonstrated anti-inflammatory effects of SMF-exposure.

The influence of spatial pulsed magnetic field application on neuropathic pain after tibial nerve transection in rat

The purpose of the study was to examine the influence of the spatial variable magnetic field (induction: 150-300 µT, 80-150 µT, 20-80 µT; frequency 40 Hz) on neuropathic pain after tibial nerve transection. The experiments were carried out on 64 male Wistar C rats. The exposure of animals to magnetic field was performed 1 d/20 min., 5 d/week, for 28 d. Behavioural tests assessing the intensity of allodynia and sensitivity to mechanical and thermal stimuli were conducted 1 d prior to surgery and 3, 7, 14, 21 and 28 d after the surgery. The extent of autotomy was examined. Histological and immunohistochemical analysis was performed. The use of extremely low-frequency magnetic fields of minimal induction values (20-80 µT/40 Hz) decreased pain in rats after nerve transection. The nociceptive sensitivity of healthy rats was not changed following the exposition to the spatial magnetic field of the low frequency. The results of histological and immunohistochemical investigations confirm those findings. Our results indicate that extremely low-frequency magnetic field may be useful in the neuropathic pain therapy.

Exposure to static magnetic field delays induced preterm birth occurrence in mice

OBJECTIVE

The purpose of this study was to demonstrate that daily 40-minute whole body exposure to an inhomogeneous static magnetic field (SMF) prolongs induced preterm birth (PTB) in mice.

STUDY DESIGN

The murine model for PTB induction was performed by the administration of 25 μg/animal lipopolysaccharide (LPS) intraperitoneally. The applied SMF was an inhomogeneous gradient field with 2.8-476.7 millitesla peak-to-peak magnetic induction range by 10 mm lateral periodicity. During SMF exposure, mice were free to move in their cage.

RESULTS

The fetal development and the delivery were normal in animals that were exposed to SMF but not treated with LPS. SMF in these cases did not influence the term of delivery. In LPS-challenged animals, SMF exposure prolonged the time of PTB occurrence from 17.43 h (n = 7) to 21.93 h (n = 15) after the challenge (P < .05).

CONCLUSION

Exposure to inhomogeneous SMF may have a valuable effect in the prevention of PTB and may have clinical relevance to humans.