Transient and steady-state magnetic fields induce increased fluorodeoxyglucose uptake in the rat hindbrain.

Abstract

We inquired into the biophysical basis of the ability of weak electromagnetic fields (EMFs) to trigger onset and offset evoked potentials, and to produce steady-state changes in the electroencephalogram (EEG). Rats were exposed to a 2.5-G, 60-Hz magnetic field and the neuroanatomical region of glucose activation associated with the effect of the field on the EEG was identified by positron emission tomography (PET) using fluorodeoxyglucose (FDG). Paired emission scans from the same animal with and without field treatment were differenced and averaged, and t values of the brain voxels computed using the pooled standard deviation were compared with a calculated critical t value to identify the field-activated voxels. Increased glucose utilization occurred in hindbrain voxels when the field was applied orthogonally to the sagittal plane, but not when the angle between the field and the sagittal plane varied randomly. Distinct FDG activation effects were observed in response to transient (both onset and offset) and steady-state magnetic stimuli. Observations of increased glucose utilization induced by magnetic stimuli and its dependence on the direction of the field suggested that signal transduction was mediated by a force detector and that the process and/or early post-transduction processing occurred in the hindbrain.

AI evidence extraction

Main findings

Rats exposed to a 2.5-G, 60-Hz magnetic field showed increased glucose utilization (FDG uptake) in hindbrain voxels when the field was applied orthogonally to the sagittal plane, but not when the field direction varied randomly. Distinct FDG activation effects were reported for transient (onset/offset) versus steady-state magnetic stimuli.

Outcomes measured

• FDG (fluorodeoxyglucose) uptake / glucose utilization in brain (PET)
• EEG changes (context for identifying activation region)

Limitations

• Sample size not reported in abstract
• Exposure duration not reported in abstract
• Outcome is metabolic activation (FDG uptake) rather than a clinical/behavioral endpoint
• Details of randomization/blinding and statistical correction for multiple voxel comparisons not described in abstract

Suggested hubs

• occupational-exposure (0.25)
  Study involves ELF (60 Hz) magnetic-field exposure, which is commonly relevant to occupational ELF contexts, though no workplace setting is specified.

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    "population": "Rats",
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    "outcomes": [
        "FDG (fluorodeoxyglucose) uptake / glucose utilization in brain (PET)",
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    ],
    "main_findings": "Rats exposed to a 2.5-G, 60-Hz magnetic field showed increased glucose utilization (FDG uptake) in hindbrain voxels when the field was applied orthogonally to the sagittal plane, but not when the field direction varied randomly. Distinct FDG activation effects were reported for transient (onset/offset) versus steady-state magnetic stimuli.",
    "effect_direction": "harm",
    "limitations": [
        "Sample size not reported in abstract",
        "Exposure duration not reported in abstract",
        "Outcome is metabolic activation (FDG uptake) rather than a clinical/behavioral endpoint",
        "Details of randomization/blinding and statistical correction for multiple voxel comparisons not described in abstract"
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    "evidence_strength": "low",
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    "peer_reviewed_likely": "yes",
    "keywords": [
        "ELF magnetic field",
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        "glucose utilization",
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        "steady-state"
    ],
    "suggested_hubs": [
        {
            "slug": "occupational-exposure",
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}

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