From the Cover: 2.45-GHz Microwave Radiation Impairs Hippocampal Learning and Spatial Memory: Involvement of Local Stress Mechanism-Induced Suppression of iGluR/ERK/CREB Signaling.

Abstract

Microwave (MW) radiation induced oxidative stress reduces dendritic arborization, spine density and number of hippocampal pyramidal neurons and hence, impair learning and spatial memory through p53-dependent/independent apoptosis of hippocampal neuronal and nonneuronal cells. However, the mechanisms responsible for MW radiation induced impairment in memory formation remains still unknown. This study elucidates the effect of short (15 days) and long-term (30 and 60 days) low level 2.45 GHz MW radiation-induced local stress on the hippocampal spatial memory formation pathway in adult male mice. Twelve-weeks old mice were exposed to 2.45 GHz MW radiation (continuous-wave with overall average Power density of 0.0248 mW/cm2 and overall average whole body SAR value of 0.0146 W/Kg) @ 2 h/d for 15, 30, and 60 days. Learning and spatial memory was assessed by 8-arm radial maze. We have investigated the alterations in serum corticosterone level and the expression of glucocorticoid receptor, corticotropin-releasing hormone (CRH), inducible nitric oxide synthase (i-NOS), iGluRs, PSD-95-neuronal NOS (n-NOS) system, protein kinase A, protein kinase Cε-ERK1/2-pERK1/2 in all the hippocampal subregions, viz. CA1, CA2, CA3, and DG through immunohistochemistry/immunofluorescence and alterations in the expression of hippocampal glucocorticoid receptor, CRH-receptor 1 (CRH-R1), cAMP-response element-binding (CREB), and phosphorylated-CREB (p-CREB) through western blot analysis. We observed that 2.45 GHz MW irradiated mice showed slow learning and significantly increased number of working and reference memory errors in radial maze task. Further, 2.45 GHz MW radiation exposure increases serum corticosterone level and the expression of CRH, CRH-R1, and i-NOS, while the expression of iGluRs, n-NOS, PSD-95, protein kinase Cε, protein kinase A, ERK-p-ERK, CREB, and p-CREB decreases in above mentioned hippocampal subregions in a duration dependent manner. Our findings led us to conclude that 2.45 GHz MW radiation exposure induced local stress suppresses signaling mechanism(s) of hippocampal memory formation.

AI evidence extraction

Main findings

Mice exposed to continuous-wave 2.45 GHz microwave radiation (power density 0.0248 mW/cm2; whole-body SAR 0.0146 W/kg) showed slower learning and significantly more working and reference memory errors in an 8-arm radial maze. Exposure was associated with increased serum corticosterone and increased hippocampal CRH/CRH-R1 and i-NOS, with decreased iGluRs, PSD-95, n-NOS, PKA/PKCε-ERK signaling, and CREB/p-CREB in hippocampal subregions in a duration-dependent manner.

Outcomes measured

• Learning and spatial memory performance (8-arm radial maze; working and reference memory errors)
• Serum corticosterone level
• Hippocampal expression of glucocorticoid receptor, CRH, CRH-R1, i-NOS
• Hippocampal expression of iGluRs, PSD-95, n-NOS
• Hippocampal signaling proteins: PKA, PKCε, ERK1/2, pERK1/2, CREB, p-CREB

Limitations

• Sample size not reported in abstract
• Only adult male mice studied; generalizability to other sexes/ages/species not addressed in abstract
• Exposure conditions are specific (continuous-wave; stated power density/SAR; 2 h/day) and may not generalize to other exposure patterns
• Mechanistic measures are associative; causal pathway not fully established in abstract

Suggested hubs

• school-wi-fi (0.55)
  Uses 2.45 GHz microwave frequency commonly associated with Wi‑Fi, though the source is not explicitly stated.

{
    "study_type": "animal",
    "exposure": {
        "band": "microwave",
        "source": null,
        "frequency_mhz": 2450,
        "sar_wkg": 0.01460000000000000013045120539345589349977672100067138671875,
        "duration": "2 h/day for 15, 30, or 60 days"
    },
    "population": "Adult male mice (12 weeks old)",
    "sample_size": null,
    "outcomes": [
        "Learning and spatial memory performance (8-arm radial maze; working and reference memory errors)",
        "Serum corticosterone level",
        "Hippocampal expression of glucocorticoid receptor, CRH, CRH-R1, i-NOS",
        "Hippocampal expression of iGluRs, PSD-95, n-NOS",
        "Hippocampal signaling proteins: PKA, PKCε, ERK1/2, pERK1/2, CREB, p-CREB"
    ],
    "main_findings": "Mice exposed to continuous-wave 2.45 GHz microwave radiation (power density 0.0248 mW/cm2; whole-body SAR 0.0146 W/kg) showed slower learning and significantly more working and reference memory errors in an 8-arm radial maze. Exposure was associated with increased serum corticosterone and increased hippocampal CRH/CRH-R1 and i-NOS, with decreased iGluRs, PSD-95, n-NOS, PKA/PKCε-ERK signaling, and CREB/p-CREB in hippocampal subregions in a duration-dependent manner.",
    "effect_direction": "harm",
    "limitations": [
        "Sample size not reported in abstract",
        "Only adult male mice studied; generalizability to other sexes/ages/species not addressed in abstract",
        "Exposure conditions are specific (continuous-wave; stated power density/SAR; 2 h/day) and may not generalize to other exposure patterns",
        "Mechanistic measures are associative; causal pathway not fully established in abstract"
    ],
    "evidence_strength": "low",
    "confidence": 0.7800000000000000266453525910037569701671600341796875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "2.45 GHz",
        "microwave radiation",
        "mouse",
        "hippocampus",
        "spatial memory",
        "radial maze",
        "corticosterone",
        "CRH",
        "iNOS",
        "iGluR",
        "ERK",
        "CREB",
        "oxidative stress",
        "local stress"
    ],
    "suggested_hubs": [
        {
            "slug": "school-wi-fi",
            "weight": 0.5500000000000000444089209850062616169452667236328125,
            "reason": "Uses 2.45 GHz microwave frequency commonly associated with Wi‑Fi, though the source is not explicitly stated."
        }
    ]
}

Comments

Log in to comment.

No comments yet.