Exposure to 2.45 GHz electromagnetic fields elicits an HSP-related stress response in rat hippocampus.

Abstract

The issue of possible neurobiological effects of the electromagnetic field (EMF) exposure is highly controversial. To determine whether electromagnetic field exposure could act as an environmental stimulus capable of producing stress responses, we employed the hippocampus, a sensitive target of electromagnetic radiation, to assess the changes in its stress-related gene and protein expression after EMF exposure. Adult male Sprague-Dawley rats with body restrained were exposed to a 2.45 GHz EMF at a specific absorption rate (SAR) of 6 W/kg or sham conditions. cDNA microarray was performed to examine the changes of gene expression involved in the biological effects of electromagnetic radiation. Of 2048 candidate genes, 23 upregulated and 18 downregulated genes were identified. Of these differential expression genes, two heat shock proteins (HSP), HSP27 and HSP70, are notable because expression levels of both proteins are increased in the rat hippocampus. Result from immunocytochemistry revealed that EMF caused intensive staining for HSP27 and HSP70 in the hippocampus, especially in the pyramidal neurons of cornu ammonis 3 (CA3) and granular cells of dentate gyrus (DG). The gene and protein expression profiles of HSP27 and HSP70 were further confirmed by reverse transcription polymerase chain reaction (RT-PCR) and Western blot. Our data provide direct evidence that exposure to electromagnetic fields elicits a stress response in the rat hippocampus.

AI evidence extraction

Main findings

Rats exposed to 2.45 GHz EMF (SAR 6 W/kg) showed differential hippocampal gene expression (23 upregulated, 18 downregulated of 2048 genes). HSP27 and HSP70 were increased in the hippocampus, with immunocytochemistry showing more intensive staining particularly in CA3 pyramidal neurons and dentate gyrus granular cells; RT-PCR and Western blot confirmed these changes.

Outcomes measured

• Hippocampal gene expression changes (cDNA microarray)
• HSP27 expression in hippocampus (gene/protein)
• HSP70 expression in hippocampus (gene/protein)
• Immunocytochemistry staining intensity/localization in hippocampus (CA3, dentate gyrus)

Limitations

• Exposure duration not reported in abstract
• Sample size not reported in abstract
• Only adult male rats studied (generalizability limited)
• Body restraint may influence stress-related outcomes and could confound interpretation
• Outcome focused on stress-response markers (HSPs) rather than functional/behavioral endpoints

{
    "study_type": "animal",
    "exposure": {
        "band": "microwave",
        "source": null,
        "frequency_mhz": 2450,
        "sar_wkg": 6,
        "duration": null
    },
    "population": "Adult male Sprague-Dawley rats (body restrained)",
    "sample_size": null,
    "outcomes": [
        "Hippocampal gene expression changes (cDNA microarray)",
        "HSP27 expression in hippocampus (gene/protein)",
        "HSP70 expression in hippocampus (gene/protein)",
        "Immunocytochemistry staining intensity/localization in hippocampus (CA3, dentate gyrus)"
    ],
    "main_findings": "Rats exposed to 2.45 GHz EMF (SAR 6 W/kg) showed differential hippocampal gene expression (23 upregulated, 18 downregulated of 2048 genes). HSP27 and HSP70 were increased in the hippocampus, with immunocytochemistry showing more intensive staining particularly in CA3 pyramidal neurons and dentate gyrus granular cells; RT-PCR and Western blot confirmed these changes.",
    "effect_direction": "harm",
    "limitations": [
        "Exposure duration not reported in abstract",
        "Sample size not reported in abstract",
        "Only adult male rats studied (generalizability limited)",
        "Body restraint may influence stress-related outcomes and could confound interpretation",
        "Outcome focused on stress-response markers (HSPs) rather than functional/behavioral endpoints"
    ],
    "evidence_strength": "low",
    "confidence": 0.7800000000000000266453525910037569701671600341796875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "2.45 GHz",
        "microwave",
        "EMF",
        "SAR 6 W/kg",
        "rat",
        "hippocampus",
        "heat shock proteins",
        "HSP27",
        "HSP70",
        "stress response",
        "gene expression",
        "microarray",
        "immunocytochemistry",
        "RT-PCR",
        "Western blot"
    ],
    "suggested_hubs": []
}

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