Chronic 3.5 GHz radiofrequency exposure is associated with behavioral, molecular, and histopathological changes in the rat hippocampus.

Abstract

PURPOSE: Chronic exposure to mid-band radiofrequency (RF) electromagnetic fields at 3.5 GHz is increasingly relevant to modern wireless environments; however, its effects on hippocampal circuit stability under non-thermal conditions remain unclear. We investigated whether prolonged 3.5-GHz RF exposure is associated with anxiety-like behavior and hippocampal transcript-level changes consistent with excitatory-inhibitory (E/I) imbalance, and whether thymoquinone (TQ) or taurine (TAU) are associated with modulation of these responses. MATERIALS AND METHODS: Adult male Wistar rats ( = 28) were assigned to Sham, RF, RF + TQ (20 mg/kg), or RF + TAU (20 mg/kg) groups ( = 7/group). Animals were exposed to a GSM-like 3.5-GHz RF signal (2 W; 2 h/day; 5 days/week; 10 weeks). Anxiety-like behavior and spatial learning were assessed using the Elevated Plus Maze (EPM) and Morris Water Maze (MWM). Hippocampal gene expression () was quantified by RT-qPCR, and histopathology by H&E staining. RESULTS: Dosimetry indicated whole-body SAR of 0.0383 W/kg and brain gray matter SAR of 0.3411 W/kg. RF exposure was associated with reduced open-arm time in the EPM. Expression of increased in the RF group, suggesting a shift toward excitation. Under RF co-exposure conditions, TQ and TAU were associated with changes in expression and with increases in , , and , along with inhibitory and monoaminergic markers. RF-exposed hippocampi showed neuronal degeneration, less pronounced in antioxidant-treated groups. CONCLUSIONS: Chronic non-thermal 3.5-GHz RF exposure is associated with anxiety-like behavior and a hippocampal molecular-structural profile consistent with E/I imbalance and tissue stress. TQ and TAU were associated with context-dependent changes under RF co-exposure conditions; however, due to the absence of antioxidant-only control groups, independent effects cannot be determined. These findings suggest that synaptic homeostasis may represent a potential target of prolonged mid-band RF exposure.

AI evidence extraction

Main findings

In adult male Wistar rats, chronic 3.5 GHz RF exposure (whole-body SAR 0.0383 W/kg; brain gray matter SAR 0.3411 W/kg) was associated with reduced open-arm time in the Elevated Plus Maze, increased hippocampal expression of a marker interpreted by the authors as suggesting a shift toward excitation, and neuronal degeneration in the hippocampus. In RF co-exposure groups, thymoquinone and taurine were associated with changes in gene-expression markers and less pronounced neuronal degeneration, but independent effects could not be determined because antioxidant-only control groups were absent.

Outcomes measured

• Anxiety-like behavior (Elevated Plus Maze)
• Spatial learning (Morris Water Maze)
• Hippocampal gene expression by RT-qPCR
• Hippocampal histopathology (H&E staining)
• Neuronal degeneration
• Markers consistent with excitatory-inhibitory imbalance

Limitations

• Animal study
• Small sample size (n=28; 7/group)
• Absence of antioxidant-only control groups prevents determination of independent effects of thymoquinone or taurine
• Abstract does not report all gene targets explicitly
• Non-thermal exposure interpretation is based on study description

{
    "study_type": "animal",
    "exposure": {
        "band": "RF",
        "source": "other",
        "frequency_mhz": 3500,
        "sar_wkg": 0.341100000000000014299672557172016240656375885009765625,
        "duration": "2 h/day; 5 days/week; 10 weeks"
    },
    "population": "Adult male Wistar rats",
    "sample_size": 28,
    "outcomes": [
        "Anxiety-like behavior (Elevated Plus Maze)",
        "Spatial learning (Morris Water Maze)",
        "Hippocampal gene expression by RT-qPCR",
        "Hippocampal histopathology (H&E staining)",
        "Neuronal degeneration",
        "Markers consistent with excitatory-inhibitory imbalance"
    ],
    "main_findings": "In adult male Wistar rats, chronic 3.5 GHz RF exposure (whole-body SAR 0.0383 W/kg; brain gray matter SAR 0.3411 W/kg) was associated with reduced open-arm time in the Elevated Plus Maze, increased hippocampal expression of a marker interpreted by the authors as suggesting a shift toward excitation, and neuronal degeneration in the hippocampus. In RF co-exposure groups, thymoquinone and taurine were associated with changes in gene-expression markers and less pronounced neuronal degeneration, but independent effects could not be determined because antioxidant-only control groups were absent.",
    "effect_direction": "harm",
    "limitations": [
        "Animal study",
        "Small sample size (n=28; 7/group)",
        "Absence of antioxidant-only control groups prevents determination of independent effects of thymoquinone or taurine",
        "Abstract does not report all gene targets explicitly",
        "Non-thermal exposure interpretation is based on study description"
    ],
    "evidence_strength": "low",
    "confidence": 0.92000000000000003996802888650563545525074005126953125,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "3.5 GHz",
        "radiofrequency",
        "RF exposure",
        "mid-band",
        "rat",
        "Wistar",
        "hippocampus",
        "anxiety-like behavior",
        "excitatory-inhibitory imbalance",
        "gene expression",
        "histopathology",
        "SAR",
        "thymoquinone",
        "taurine"
    ],
    "suggested_hubs": []
}

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