Changes in synaptic efficacy and seizure susceptibility in rat brain slices following extremely low-frequency electromagnetic field exposure.

Bioelectromagnetics · 2009 · Mixed · Low evidence

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MixedLow evidencePaper 4950

Study snapshot

PublicationBioelectromagnetics · 2009

Study typeanimal

Reported directionMixed

Evidence ratingLow

Abstract

The effects of electromagnetic fields (EMFs) on living organisms are recently a focus of scientific interest, as they may influence everyday life in several ways. Although the neural effects of EMFs have been subject to a considerable number of investigations, the results are difficult to compare since dissimilar exposure protocols have been applied on different preparations or animals. In the present series of experiments, whole rats or excised rat brain slices were exposed to a reference level-intensity (250-500 microT, 50 Hz) EMF in order to examine the effects on the synaptic efficacy in the central nervous system. Electrophysiological investigation was carried out ex vivo, on neocortical and hippocampal slices; basic synaptic functions, short- and long-term plasticity and seizure susceptibility were tested. The most pronounced effect was a decrease in basic synaptic activity in slices treated directly ex vivo observed as a diminution in amplitude of evoked potentials. On the other hand, following whole-body exposure an enhanced short- and long-term synaptic facilitation in hippocampal slices and increased seizure susceptibility in neocortical slices was also observed. However, these effects seem to be transient. We can conclude that ELF-EMF exposure exerts significant effects on synaptic activity, but the overall changes may strongly depend on the synaptic structure and neuronal network of the affected region together with the specific spatial parameters and constancy of EMF.

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AI evidence extraction

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Study typeanimal

Effect directionmixed

PopulationRats; excised rat neocortical and hippocampal brain slices (ex vivo electrophysiology)

Sample sizeNot supplied

ExposureELF · 0.05 MHz

Evidence strengthLowConfidence: 78% · Peer reviewed: yes

Main findings

Rats or excised rat brain slices were exposed to 50 Hz ELF-EMF at 250–500 microT. Direct ex vivo exposure of slices decreased basic synaptic activity (reduced evoked potential amplitude). After whole-body exposure, hippocampal slices showed enhanced short- and long-term synaptic facilitation and neocortical slices showed increased seizure susceptibility; these effects were described as transient.

Outcomes measured

synaptic efficacy
basic synaptic activity (amplitude of evoked potentials)
short-term synaptic plasticity/facilitation
long-term synaptic plasticity/facilitation
seizure susceptibility

Limitations

Exposure duration not reported in abstract
Sample size not reported in abstract
Findings differed by exposure condition (direct slice exposure vs whole-body exposure) and brain region, limiting comparability

View raw extracted JSON

{
  "study_type": "animal",
  "exposure": {
    "band": "ELF",
    "source": null,
    "frequency_mhz": 0.05,
    "sar_wkg": null,
    "duration": null
  },
  "population": "Rats; excised rat neocortical and hippocampal brain slices (ex vivo electrophysiology)",
  "sample_size": null,
  "outcomes": [
    "synaptic efficacy",
    "basic synaptic activity (amplitude of evoked potentials)",
    "short-term synaptic plasticity/facilitation",
    "long-term synaptic plasticity/facilitation",
    "seizure susceptibility"
  ],
  "main_findings": "Rats or excised rat brain slices were exposed to 50 Hz ELF-EMF at 250–500 microT. Direct ex vivo exposure of slices decreased basic synaptic activity (reduced evoked potential amplitude). After whole-body exposure, hippocampal slices showed enhanced short- and long-term synaptic facilitation and neocortical slices showed increased seizure susceptibility; these effects were described as transient.",
  "effect_direction": "mixed",
  "limitations": [
    "Exposure duration not reported in abstract",
    "Sample size not reported in abstract",
    "Findings differed by exposure condition (direct slice exposure vs whole-body exposure) and brain region, limiting comparability"
  ],
  "evidence_strength": "low",
  "confidence": 0.78,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "ELF-EMF",
    "50 Hz",
    "250-500 microT",
    "rat",
    "brain slices",
    "hippocampus",
    "neocortex",
    "synaptic efficacy",
    "synaptic plasticity",
    "seizure susceptibility",
    "evoked potentials"
  ],
  "suggested_hubs": [
    {
      "slug": "occupational-exposure",
      "weight": 0.25,
      "reason": "Uses ELF (50 Hz) magnetic field exposure levels that may be relevant to power-frequency exposure contexts, though the source is not specified."
    }
  ]
}

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AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.

Identifiers and source

DOI: 10.1002/bem.20517
PubMed: 19572331

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