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Medical/biological Study (experimental study)

Neurodevelopmental anomalies of the hippocampus in rats exposed to weak intensity complex magnetic fields throughout gestation. med./biol.

By: Fournier NM, Mach QH, Whissell PD, Persinger MA
Published in: Int J Dev Neurosci 2012; 30 (6): 427 - 433 (PubMed | Journal website)

Aim of study (according to author)
To investigate the effect of weak intensity magnetic fields on the prenatal brain development.
Background/further details:
Pregnant rats were continuously exposed to one of four intensities during the pregnancy: 1.) 5-20 nT, 2.) 30-50 nT, 3.) 90-580 nT und 4.) 90-1200 nT (n=2 per group). After one year, the male offspring (n=6-7 per group) were used in the open field test and the contextual fear conditioning was examined. Additionally, the number and the structure of hippocampal neurons were analyzed (n=4 per group).
Previous studies showed that there were no differences between rats exposed to a weak magnetic field of 5-20 nT and a control group without any magnetic field. Therefore, in this study, the reference group (5-20 nT) was used as a control.
The experiment was performed twice.

Endpoints

Exposure
General category: magnetic field, low frequency field, signals/pulses, 50/60 Hz

Field characteristicsParameters
50 Hz
pulsed (PW)
exposure duration: continuous to different field patterns for 24 h/day during gestation (21 days)
magnetic flux density: 20 nT max value (B = 5 - 20 nT reference group)
magnetic flux density: 50 nT max value (B = 30 - 50 nT low-intensity group)
magnetic flux density: 580 nT max value (B = 90 - 580 nT medium-intensity group)
magnetic flux density: 1200 nT max value (B = 590 - 1200 nT high-intensity group)

FIELD View further expo parameters

Exposed system:
animal (species/strain): rat/Wistar albino
whole body exposure: in utero

Methods
Endpoint/Measurement parameters/Methodology

investigated material: tissue slices (in vitro)
investigation on living organism
investigated organ system: brain/CNS

time of investigation: after exposure

Main outcome of study (according to author)
Individual analyses of open field related behaviors revealed no significant differences between any of the exposure conditions. In the fear conditioning, it was found that exposure to the low-intensity (30-50 nT) complex magnetic field during prenatal development resulted in a significant reduction of freezing time compared to the reference group (5-20 nT). Additionally, rats exposed to the low-intensity (30-50 nT) complex magnetic field showed anomalies in the cytological and morphological development of the hippocampus (reduction in overall hippocampal size and promoted subtle malformation of some regions) as compared to the reference group (5-20 nT). In contrast, exposure to weaker or stronger intensities of the same complex magnetic field did not interfere with hippocampal development or anxiety behavior.
These findings suggest that prenatal exposure to complex magnetic fields of a narrow intensity window during development could result in subtle but permanent alterations in hippocampal structure and function.

(Study character: medical/biological study, experimental study, full/main study, blind study (only morphological examination of brain))

Study funded by

Related articles i
Glossary: 50/60 Hz, animal, anxiety, behavior, biological, blind study, brain, CNS, cognitive, conditioning, control group, cytological, endpoint, exposed, exposure, frequency, full/main study, gestation, glial cells, hippocampus, in utero, in vitro, light microscopy, locomotor activity, low frequency field, magnetic field, magnetic flux density, malformation, medium, morphological, neurological, Neurons, open field, organism, pregnant, prenatal, pulsed, Pulses, PW, rat/Wistar, rats, reduction, significant, species, strain, tissue, whole body exposure
Exposure: magnetic field, low frequency field, signals/pulses, 50/60 Hz

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