Suppression of Experimental Allergic Encephalomyelitis in Rats Exposed Nocturnally to Magnetic Fields

Effect of weak combined static and extremely low-frequency alternating magnetic fields on spatial memory and brain amyloid-β in two animal models of Alzheimer's disease

Subchronic effect of a weak combined magnetic field (MF), produced by superimposing a constant component, 42 µT and an alternating MF of 0.08 µT, which was the sum of two frequencies of 4.38 and 4.88 Hz, was studied in olfactory bulbectomized (OBE) and transgenic Tg (APPswe, PSEN1) mice, which were used as animal models of sporadic and heritable Alzheimer's disease (AD) accordingly. Spatial memory was tested in a Morris water maze on the following day after completion of training trials with the hidden platform removed. The amyloid-β (Aβ) level was determined in extracts of the cortex and hippocampus of mice using a specific DOT analysis while the number and dimensions of amyloid plaques were detected after their staining with thioflavin S in transgenic animals. Exposure to the MFs (4 h/day for 10 days) induced the decrease of Aβ level in brain of OBE mice and reduced the number of Aβ plaques in the cortex and hippocampus of Tg animals. However, memory improvement was revealed in Tg mice only, but not in the OBE animals. Here, we suggest that in order to prevent the Aβ accumulation, MFs could be used at early stage of neuronal degeneration in case of AD and other diseases with amyloid protein deposition in other tissues.

Lithium ion "cyclotron resonance" magnetic fields decrease seizure onset times in lithium-pilocarpine seized rats

The cyclotron resonance equation predicts that the frequency of an applied magnetic field that might optimally interact with a single ion species may be computed as a function of the charge-to-mass ratio of the ion and the strength of the background static magnetic field. The present study was undertaken to discern the applicability of this equation for optimizing lithium ion utilization in the rat, as inferred by the predicted magnetic "ion resonance "field-induced shift of lithium's dose-dependent curve for seizure onset times (SOTs) when combined with the cholinergic agent pilocarpine. Groups of rats were administered 1.5 thru 3 mEq/kg lithium chloride (in 0.5 mEq/kg increments) and exposed to reference conditions or to one of three intensities (70 nanoTesla, 0.8 microTesla, or 25 microTesla) of a 85 Hz magnetic field calculated to resonate with lithium ions given the background static geomagnetic field of approximately 38,000 nanoTesla (0.38 Gauss). A statistically significant quadratic relationship for SOT as a function of magnetic field intensity (irrespective of lithium dose) was noted: this U-shaped function was characterized by equal SOTs for the reference and 25 microTesla groups, with a trend toward shorter SOTs for the 70 nanoTesla and 0.8 microTesla groups. Although not predicted by the equations, this report extends other findings suggestive of discrete intensity windows for which magnetic field frequencies derived from the cyclotron ion resonance equation may affect ion activity.

Suppression of experimental allergic encephalomyelitis in rats by 50-nT, 7-Hz amplitude-modulated nocturnal magnetic fields depends on when after inoculation the fields are applied

Female Lewis rats (n = 88) were inoculated with an emulsion of spinal cord and complete Freund's adjuvant. They were then exposed in 11 separate blocks of experiments over a year period for approximately 6 min every hour between midnight and 08:00 h during post-inoculation nights 1-7, 8-16, 1-16, or 9 and 10 to 50-nT, 7-Hz, amplitude-modulated magnetic fields or to sham field (control) conditions. Compared to the control rats those exposed to the magnetic fields for nights 1-7 and nights 9-10 displayed more severe clinical symptoms while those exposed for nights 1-16 or 8-16 showed less severe symptoms. There was a strong correlation between the severity of the clinical symptoms in the control groups and the global geomagnetic activity 9 and 10 days after inoculation. These results suggest that the immunosuppressive effects of weak nocturnal magnetic fields may depend upon when they are applied during various stages in the development of a disease.

Geophysical variables and behavior: XCI. Ambulatory behavior in rats following prenatal exposures to complex magnetic fields designed to interact with genetic expression

A total of 45 litters were exposed during their entire prenatal development to one of two complex patterns of magnetic fields whose strengths varied within one of four intensity ranges between 10 nT and 1,000 nT or to sham-field conditions. The litters exposed to the most complex pattern, composed of 50 200-msec. presentations of different pulses for 10 sec. every 50 sec., displayed more ambulation in an open field at 21 days of age than the litters that had been exposed continuously to a repetitive frequency-modulated field or to sham-field conditions. This treatment explained 25% of the variance in the numbers of squares traversed. The results suggest that complexity of the applied magnetic field during prenatal development may be more important than intensity for permanently affecting neuronal organization and behavior.

Suppression of experimental allergic encephalomyelitis is specific to the frequency and intensity of nocturnally applied, intermittent magnetic fields in rats

Female Lewis rats (n=72) were inoculated with an emulsion of spinal cord and complete Freund's adjuvant. They were then exposed for approximately 6 min every hour between midnight and 08:00 h for 2 weeks to either 7 or 40 Hz amplitude-modulated magnetic fields whose temporal pattern was designed to simulate a (geomagnetic) storm sudden commencement. The peak strengths of the fields averaged between either 30-50 nT (low intensity) or 500 nT (high intensity). Rats exposed to the 7 Hz, low intensity magnetic fields displayed significantly less severe overt signs of experimental allergic encephalomyelitis than rats exposed to either of the two intensities of the 40 Hz fields, the high intensity 7 Hz field, or the reference (<10 nT) condition. The latter groups did not differ significantly from each other. Predicted severity based upon the numbers of foci of infiltrations of lymphocytes within the brains of the rats also demonstrated the ameliorating effects of the low intensity, 7 Hz exposures. These results suggest very specific characteristics of complex, weak magnetic fields within the sleeping environment could affect the symptoms of autoimmunity.