Medical/biological study (experimental study)

Low-frequency magnetic fields do not aggravate disease in mouse models of Alzheimer's disease and amyotrophic lateral sclerosis med./bio.

By: Liebl MP, Windschmitt J, Besemer AS, Schafer AK, Reber H, Behl C, Clement AM

Published in: Sci Rep 2015; 5: 8585

Aim of study (acc. to author)

The effects of a chronic exposure of mice to a 50 Hz magnetic field on the development of Alzheimer's disease and amyotrophic lateral sclerosis should be investigated.

Background/further details

APP23 mice with an overexpression of the amyloid precursor protein (APP) were used as a model for early onset of Alzheimer's disease. SOD1^G85R and SOD^G93A mice with an overexpression of mutant superoxide dismutase 1 (SOD-1) were used as models for amyotrophic lateral sclerosis. SOD1^WT mice, overexpressing human wild type SOD-1, were used as negative controls for the SOD mutation. All mice were 2 month old when the experiment started.
The following groups were used: 1) APP23 mice exposed to the magnetic field (n=?), 2) sham exposed APP23 mice (n=?), 3) SOD1^G85R mice exposed to the magnetic field (n=135), 4) sham exposed SOD1^G85R mice (n=138), 5) SOD1^G93A mice exposed to the magnetic field (n=122), 6) sham exposed SOD1^G93A mice (n=110), 7) non-exposed SOD1^WT mice (n=?), 8) non-exposed non-transgenic littermates (n=?).

Endpoint

effects on the neurological system: initiation and progression of Alzheimer's disease and amyotrophic lateral sclerosis

Exposure

- 50 Hz
- 50/60 Hz
- magnetic field

Exposure	Parameters
Exposure 1: 50 Hz Exposure duration: continuous for 16 months	magnetic flux density: 1 mT

Exposure 1

Main characteristics

Frequency	50 Hz
Type	magnetic field
Exposure duration	continuous for 16 months

Exposure setup

Exposure source	Merritt coils
Chamber	cages without metal
Setup	several mouse cages were placed in one module on three levels within the homogeneous field; Merritt coils consisted of two coils of 26 and 11 turns each which were connected in series; the cable consisted of five wires with a total cross-section area of 16 mm²; wires were wrapped in aluminum foil to block electric fields; exposure units were shielded to prevent fringing
Sham exposure	A sham exposure was conducted.
Additional info	modules for sham exposure looked identical to the modules for exposure, but wires were turned after half of the turns

Parameters

Measurand	Value	Type	Method	Mass	Remarks
magnetic flux density	1 mT	-	measured	-	-

Additional parameter details

2 µT was the maximum magnetic flux density measured in the sham exposure modules

Reference articles

Merritt R et al. (1983): Uniform magnetic field produced by three, four, and five square coils

Exposed system:

animal
mouse/APP23, SOD1^G85R, SOD1^G93A, SOD1^WT, wild type
whole body

Methods Endpoint/measurement parameters/methodology

molecular biosynthesis: gene expression of SOD-1 in SOD mice (quantitative real-time PCR); total protein concentration in fractions (BCA assay), amount of carbonylated proteins (derivatization with dinitrophenylhydrazin), protein expression of APP, GFAP, HSP25, IBA1, SOD-1 (SDS-PAGE, Western blot), level of beta-amyloid protein (ELISA) (after 16 months)
cell function: superoxide dismutase enzyme activity (zymography and commercial kit), in SOD mice after 16 months
effects on the neurological system: number of amyloid plaques in brain of APP23 mice (hematoxylin and Kongo red staining, microscopy), activation of microglia and astrocytes (immunofluorescence staining of IBA1 and GFAP (confocal microscopy)) in all tissues after 16 months, disease course of SOD-mice (age at disease onset (after loss of 10% initial weight), age at disease end-stage (when mice were unable to right themselves up within 10 seconds))
cognitive/behavioral endpoints: spatial learning and memory of APP23 mice after 10 and 16 months (Morris water maze)
thermoregulation: body temperature (weekly)
body weight of SOD mice, survival rate, oxidative stress (see "molecular biosynthesis")

Investigated system:

DNA/RNA
tissue slices
hippocampus, cortex and spinal cord, tissue lysates, proteins
investigation on living organism

Investigated organ system:

brain/CNS

Time of investigation:

before exposure
during exposure
after exposure

Main outcome of study (acc. to author)

No significant differences were found in any parameter between exposed and sham exposed animals of all strains, respectively.
The authors conclude that chronic exposure of mice to a 50 Hz magnetic field has no effects on the development, course or symptoms of Alzheimer's disease and amyotrophic lateral sclerosis.

Study character:

medical/biological study
experimental study
full/main study
partially blind study

Study funded by

Bundesamt für Strahlenschutz (BfS; Federal Office for Radiation Protection), Salzgitter, Germany

Zuo H et al. (2020): The mitochondria/caspase-dependent apoptotic pathway plays a role in the positive effects of a power frequency electromagnetic field on Alzheimer's disease neuronal model
Akbarnejad Z et al. (2018): Spatial memory recovery in Alzheimer's rat model by electromagnetic field exposure
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