Morphological changes in cerebellum of neonatal rats exposed to 2.45 GHz microwaves.

Abstract

One-day and six-day old Sprague-Dawley rats were exposed in the far field to 2.45 GHz (cw) microwaves at 10 mW/cm2 for five consecutive days, 7 hours per day (SAR 2W/kg). Pups were euthenized one day after exposure and the cerebella processed for light and electron microscopy. Matching cerebellar sections and folia from irradiated and sham irradiated animals were examined. Light microscopic examination revealed the presence of small deeply-stained cells with hyperchromatic pyknotic nuclei within the external granular layer (EGL). The number of these pyknotic cells in the experimental animals was nearly twice that in the controls. The Nissl bodies in Purkinje cells were finely dispersed. In some experimental animals mononuclear cellular infiltration was demonstrated. Under the electron microscope the deeply-stained pyknotic small cells presented electron dense nuclei with clumped chromatin, extrusion or disintegration of the nucleus, ruptured nuclear membrane, and the vacuolization of the cytoplasm. Eventually these cells became phagocytosed by surrounding EGL cells. Most of the Purkinje cells of experimental animals showed small, disorderly arrays of rough endoplasmic reticulum (RER) instead of the typical orderly stacks of parallel arrays. These observations suggest that microwave radiation may interfere with early genesis of cerebellar microneurons and alter the metabolic status of Purkinje cells. However, this effect might be reversible.

AI evidence extraction

Main findings

Neonatal rats exposed to 2.45 GHz continuous-wave microwaves (10 mW/cm2; SAR 2 W/kg) showed nearly twice the number of small deeply stained pyknotic cells in the external granular layer compared with sham controls, along with altered Purkinje cell features (finely dispersed Nissl bodies and disordered RER arrays). Some exposed animals showed mononuclear cellular infiltration; electron microscopy described nuclear and cytoplasmic degenerative changes in pyknotic cells with subsequent phagocytosis.

Outcomes measured

• Cerebellar morphology (light microscopy)
• Cerebellar ultrastructure (electron microscopy)
• External granular layer (EGL) pyknotic cells
• Purkinje cell Nissl bodies / rough endoplasmic reticulum (RER) organization
• Mononuclear cellular infiltration

Limitations

• Sample size not reported in abstract
• Only short-term assessment (euthanized one day after exposure)
• Animal model; generalizability to humans unclear
• Reversibility is suggested but not demonstrated in the described methods/results

{
    "study_type": "animal",
    "exposure": {
        "band": "microwave",
        "source": null,
        "frequency_mhz": 2450,
        "sar_wkg": 2,
        "duration": "5 consecutive days, 7 hours/day"
    },
    "population": "One-day and six-day old Sprague-Dawley neonatal rats",
    "sample_size": null,
    "outcomes": [
        "Cerebellar morphology (light microscopy)",
        "Cerebellar ultrastructure (electron microscopy)",
        "External granular layer (EGL) pyknotic cells",
        "Purkinje cell Nissl bodies / rough endoplasmic reticulum (RER) organization",
        "Mononuclear cellular infiltration"
    ],
    "main_findings": "Neonatal rats exposed to 2.45 GHz continuous-wave microwaves (10 mW/cm2; SAR 2 W/kg) showed nearly twice the number of small deeply stained pyknotic cells in the external granular layer compared with sham controls, along with altered Purkinje cell features (finely dispersed Nissl bodies and disordered RER arrays). Some exposed animals showed mononuclear cellular infiltration; electron microscopy described nuclear and cytoplasmic degenerative changes in pyknotic cells with subsequent phagocytosis.",
    "effect_direction": "harm",
    "limitations": [
        "Sample size not reported in abstract",
        "Only short-term assessment (euthanized one day after exposure)",
        "Animal model; generalizability to humans unclear",
        "Reversibility is suggested but not demonstrated in the described methods/results"
    ],
    "evidence_strength": "low",
    "confidence": 0.7800000000000000266453525910037569701671600341796875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "2.45 GHz",
        "microwaves",
        "continuous wave",
        "SAR 2 W/kg",
        "neonatal rats",
        "cerebellum",
        "external granular layer",
        "Purkinje cells",
        "pyknotic cells",
        "electron microscopy",
        "light microscopy"
    ],
    "suggested_hubs": []
}

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