Medical/biological study (experimental study)

Exposure to 50 Hz electromagnetic radiation promote early maturation and differentiation in newborn rat cerebellar granule neurons med./bio.

By: Lisi A, Ciotti MT, Ledda M, Pieri M, Zona C, Mercanti D, Rieti S, Giuliani L, Grimaldi S

Published in: J Cell Physiol 2005; 204 (2): 532-538

Aim of study (acc. to author)

To study the effect of electromagnetic field exposure at a frequency of 50 Hz on the development of cerebellar granule neurons.

Background/further details

Granule neurons were prepared from newborn rat cerebellum (8 days after birth).
These cells represent a good model to study cellular, chemical, or electrical properties. The life span of cerebellar granule neurons in culture is known to be relatively short, and after eight days cultures, cells become sensitive to glutamate. Immature cells are glutamate receptors negative. However during development, they exhibit an increase in the expression of glutamate receptors.

Endpoint

development of cerebellar granule neurons (cellular and molecular biochemistry)

Exposure

- 50/60 Hz
- magnetic field

Exposure	Parameters
Exposure 1: 50 Hz Exposure duration: continuous for 5 days	magnetic flux density: 1 mT effective value

Exposure 1

Main characteristics

Frequency	50 Hz
Type	magnetic field
Waveform	sinusoidal
Exposure duration	continuous for 5 days

Exposure setup

Exposure source	solenoid
Setup	Both the sample and the solenoid were kept in a CO₂ incubator maintained at 37°C. Magnetic field deviation was within 5% inside the cylindrical exposure volume (14 cm x 17 cm) along the solenoid.

Parameters

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

Reference articles

Santoro N et al. (1997): Effect of extremely low frequency (ELF) magnetic field exposure on morphological and biophysical properties of human lymphoid cell line (Raji)

Exposed system:

intact cell/cell culture
rat cerebellar granule cells

Methods Endpoint/measurement parameters/methodology

molecular biosynthesis: production of heat shock proteins (Western blot); mRNA level of glutamate receptors (RT-PCR; Western blot); detection of neurofilament protein (immunofluorescence and Western blot)
cell function: membrane currents from the cell soma (induced by 200 µM of kainate; patch-clamp method)
cell viability/cell division/proliferation: neuronal survival/cell viability (glutamate toxicity, pretreated with or without MK-801)

Investigated system:

isolated bio./chem. substance
DNA/RNA
intact cell/cell culture
cell suspension

Time of investigation:

after exposure

Main outcome of study (acc. to author)

Five days challenge to electromagnetic field exposures showed a 30% decrease of cells survival, while only 5% of mortality was reported for unexposed samples. Additionally, blocking the glutamate receptor (with the glutamate competitor MK-801) no toxicity effect after exposures and glutamate was detected.
The kainate-induced currents from 6 days old exposed cells exhibited a significant increase compared to control cells.
Western blot and RT-PCR analyses showed that electromagnetic field exposure of the cerebellar granule neurons induces a change in both glutamate receptor proteins and mRNAs expression compared to control.
In addition, the use of antibody raised against neurofilament protein (NF-200) revealed an increase in NF-200 synthesis in the exposed cells.
No differences in heat shock protein expression were revealed suggesting that exposed cells are not undergoing stress induced by heat effect.
All these data suggest that exposure to non-ionizing radiations contribute to a premature expression of glutamate receptors reducing the life span of cerebellar granule neurons, leading to a more rapid cell maturation.

Study character:

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

Study funded by

Istituto Superiore per la Prevenzione e la Sicurezza del Lavoro (ISPESL; National Institute for Occupational Safety and Prevention), Italy

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Marcantonio P et al. (2010): Synergic effect of retinoic acid and extremely low frequency magnetic field exposure on human neuroblastoma cell line BE(2)C
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