Study type: Medical/biological study (experimental study)

STAT3 signalling pathway is involved in the activation of microglia induced by 2.45 GHz electromagnetic fields. med./bio.

Published in: Int J Radiat Biol 2010; 86 (1): 27-36

Aim of study (acc. to author)

To study the activation of microglia and involvement of signal transducer and activator of transcription 3 (STAT3; mediates signal transduction from the extracellular environment to the nucleus) in microglia activation after 2.45 GHz electromagnetic fields exposure.

Background/further details

Microglia is considered as a specialised macrophages residing form in the central nervous system. In response to a variety of insults, microglia adopts an activated phenotype. Microglia activation plays a pivotal role in the initiation and progression of several neurodegenerative diseases.
Some cell samples were pretreated with the JAK inhibitor pyridone 6 (P6) to study whether P6 could affect the STAT3 activation (to further demonstrate JAK2-STAT3 signal transduction (JAK is a STAT3 activator and is able to phosphorylate STAT3)). Cells were investigated 1 h, 6 h, and 12 h after exposure.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 2.45 GHz
Modulation type: pulsed
Exposure duration: continuous for 20 min
  • power: 90 mW average over time
  • SAR: 6.2 W/kg spatial average (+/- 1.5 W/kg)

Exposure 1

Main characteristics
Frequency 2.45 GHz
Type
Exposure duration continuous for 20 min
Modulation
Modulation type pulsed
Pulse width 2 µs
Packets per second 500
Exposure setup
Exposure source
Distance between exposed object and exposure source 90 cm
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
power 90 mW average over time - - -
SAR 6.2 W/kg spatial average calculated - +/- 1.5 W/kg

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

The data showed a significant increase of STAT3 DNA-binding ability after exposure. Consistent with this, the electromagnetic field exposure rapidly induced phosphorylation of STAT3 and activated JAK1 and JAK2. Additionally, electromagnetic field exposure increased transcription levels of the inflammation-associated genes (iNOS and TNF-alpha), which are reported to contain STAT-binding elements in their promoter region.
P6 reduced induction of iNOS and TNF-alpha, DNA binding activity, and activation of STAT3 in exposure-stimulated microglia cells. These findings indicate that the electromagnetic field exposure induces phosphorylation and activation of STAT3 through phosphorylation and activation of JAK.
The authors conclude that the data provide evidence that electromagnetic field exposure can initiate the activation of microglia cells and that STAT3 signal transduction is involved in electromagnetic field-induced microglial activation.

Study character:

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