Effect of 835 MHz radiofrequency radiation exposure on calcium binding proteins in the hippocampus of the mouse brain

Abstract

Worldwide expansion of mobile phones and electromagnetic field (EMF) exposure has raised question of their possible biological effects on the brain and nervous system. Radiofrequency (RF) radiation might alter intracellular signaling pathways through changes in calcium (Ca(2+)) permeability across cell membranes. Changes in the expression of calcium binding proteins (CaBP) like calbindin D28-k (CB) and calretinin (CR) could indicate impaired Ca(2+)homeostasis due to EMF exposure. CB and CR expression were measured with immunohistochemistry in the hippocampus of mice after EMF exposure at 835 MHz for different exposure times and absorption rates, 1 h/day for 5 days at a specific absorption rate (SAR)=1.6 W/kg, 1 h/day for 5 days at SAR=4.0 W/kg, 5 h/day for 1 day at SAR=1.6 W/kg, 5 h/day for 1 day at SAR=4.0 W/kg, daily exposure for 1 month at SAR=1.6 W/kg. Body weights did not change significantly. CB immunoreactivity (IR) displayed moderate staining of cells in the cornu ammonis (CA) areas and prominently stained granule cells. CR IR revealed prominently stained pyramidal cells with dendrites running perpendicularly in the CA area. Exposure for 1 month produced almost complete loss of pyramidal cells in the CA1 area. CaBP differences could cause changes in cellular Ca(2+)levels, which could have deleterious effect on normal hippocampal functions concerned with neuronal connectivity and integration.

AI evidence extraction

Main findings

CB and CR expression (immunoreactivity) were assessed in mouse hippocampus after 835 MHz exposure under several time/SAR regimens. Body weights did not change significantly. The abstract reports that 1 month of daily exposure at SAR 1.6 W/kg produced almost complete loss of pyramidal cells in the CA1 area.

Outcomes measured

• Hippocampal calbindin D28-k (CB) immunoreactivity/expression
• Hippocampal calretinin (CR) immunoreactivity/expression
• Hippocampal pyramidal cell status in CA1 area (histological observation)
• Body weight

Limitations

• Sample size not reported in the abstract/metadata
• No quantitative results or statistical comparisons for CB/CR changes are provided in the abstract
• Exposure source is discussed in the context of mobile phones, but the exact exposure setup is not described in the abstract
• Potential blinding/randomization details are not provided in the abstract

Suggested hubs

• mobile-phones (0.86)
  Study frames exposure in the context of mobile phone RF and uses 835 MHz RF exposure.

{
    "study_type": "animal",
    "exposure": {
        "band": "RF",
        "source": "mobile phone",
        "frequency_mhz": 835,
        "sar_wkg": null,
        "duration": "Multiple regimens: 1 h/day for 5 days (SAR 1.6 or 4.0 W/kg); 5 h/day for 1 day (SAR 1.6 or 4.0 W/kg); daily exposure for 1 month (SAR 1.6 W/kg)"
    },
    "population": "Mice",
    "sample_size": null,
    "outcomes": [
        "Hippocampal calbindin D28-k (CB) immunoreactivity/expression",
        "Hippocampal calretinin (CR) immunoreactivity/expression",
        "Hippocampal pyramidal cell status in CA1 area (histological observation)",
        "Body weight"
    ],
    "main_findings": "CB and CR expression (immunoreactivity) were assessed in mouse hippocampus after 835 MHz exposure under several time/SAR regimens. Body weights did not change significantly. The abstract reports that 1 month of daily exposure at SAR 1.6 W/kg produced almost complete loss of pyramidal cells in the CA1 area.",
    "effect_direction": "harm",
    "limitations": [
        "Sample size not reported in the abstract/metadata",
        "No quantitative results or statistical comparisons for CB/CR changes are provided in the abstract",
        "Exposure source is discussed in the context of mobile phones, but the exact exposure setup is not described in the abstract",
        "Potential blinding/randomization details are not provided in the abstract"
    ],
    "evidence_strength": "low",
    "confidence": 0.7399999999999999911182158029987476766109466552734375,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "835 MHz",
        "radiofrequency",
        "RF",
        "EMF",
        "mouse",
        "hippocampus",
        "calcium binding proteins",
        "calbindin D28-k",
        "calretinin",
        "immunohistochemistry",
        "SAR",
        "CA1",
        "pyramidal cells"
    ],
    "suggested_hubs": [
        {
            "slug": "mobile-phones",
            "weight": 0.85999999999999998667732370449812151491641998291015625,
            "reason": "Study frames exposure in the context of mobile phone RF and uses 835 MHz RF exposure."
        }
    ]
}

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