Effects of extremely low-frequency electric fields at different intensities and exposure durations on mismatch negativity

Abstract

The effects of extremely low-frequency electric fields (ELF-EFs, 3-300Hz) on lipid peroxidation levels and antioxidant enzyme activities have been shown in many tissues and plasma after exposure to 50-Hz alternating current (AC) electric fields. However, similar studies investigating brain lipid peroxidation status are limited. Moreover and as far as we know, no study has been conducted to examine mismatch negativity (MMN) response in rats following exposure to a 50-Hz AC electric field. Therefore, the purpose of the study was to investigate different intensities and exposure durations of ELF-EFs on MMN component of event-related potentials (ERPs) as well as apoptosis and oxidative brain damage in rats. Ninety male rats, aged 3months were used in our study. A total of six groups, composed of 15 animals each, was formed as follows: sham-exposed rats for 2weeks (C2), sham-exposed rats for 4weeks (C4), rats exposed to 12-kV/m and 18-kV/m electric fields for 2weeks (E12-2 and E18-2), rats exposed to 12- and 18-kV/m electric fields for 4weeks (E12-4 and E18-4). At the end of the experimental period, MMN responses were recorded in urethane-anesthetized rats by electrodes positioned stereotaxically to the surface of the dura. After MMN recordings, animals were killed by exsanguination and their brain tissues were removed for 4-hydroxy-2-nonenal (4-HNE), protein carbonyl and TUNEL analysis. In the current study, different change patterns in ERP parameters were observed dependent on the intensity and exposure duration of ELF-EFs. There were differences in the amplitudes of ERP between the responses to the standard and the deviant tones in all groups. When peak-to-peak amplitude of the difference curves was evaluated, MMN amplitude was significantly decreased in the E18-4 group compared with the C4 group. Additionally, the amount of 4-HNE was increased in all experimental groups compared with the control group. Consequently, it could be concluded that electric field decreased MMN amplitudes possibly induced by lipid peroxidation.

AI evidence extraction

Main findings

In rats exposed to 50-Hz AC electric fields at 12 or 18 kV/m for 2 or 4 weeks, ERP parameter changes varied by intensity and exposure duration. MMN amplitude (peak-to-peak of difference curves) was significantly decreased in the 18 kV/m for 4 weeks group compared with the 4-week sham group, and 4-HNE was increased in all exposed groups versus control.

Outcomes measured

• Mismatch negativity (MMN) / event-related potentials (ERP) parameters
• Apoptosis (TUNEL)
• Oxidative brain damage markers: 4-hydroxy-2-nonenal (4-HNE), protein carbonyl

Limitations

• No quantitative results (effect sizes, exact p-values) reported in the abstract beyond one significant MMN comparison
• Only male rats studied
• Exposure frequency stated (50 Hz) but detailed exposure regimen (e.g., hours/day) not provided in the abstract
• Mechanistic inference ('possibly induced by lipid peroxidation') is suggestive rather than demonstrated in the abstract

Suggested hubs

• animal-studies (0.9)
  Rat experiment assessing neurophysiological and oxidative stress outcomes after ELF electric-field exposure.

{
    "study_type": "animal",
    "exposure": {
        "band": "ELF",
        "source": "alternating current (AC) electric field exposure",
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": "2 weeks or 4 weeks"
    },
    "population": "Male rats (3 months old)",
    "sample_size": 90,
    "outcomes": [
        "Mismatch negativity (MMN) / event-related potentials (ERP) parameters",
        "Apoptosis (TUNEL)",
        "Oxidative brain damage markers: 4-hydroxy-2-nonenal (4-HNE), protein carbonyl"
    ],
    "main_findings": "In rats exposed to 50-Hz AC electric fields at 12 or 18 kV/m for 2 or 4 weeks, ERP parameter changes varied by intensity and exposure duration. MMN amplitude (peak-to-peak of difference curves) was significantly decreased in the 18 kV/m for 4 weeks group compared with the 4-week sham group, and 4-HNE was increased in all exposed groups versus control.",
    "effect_direction": "harm",
    "limitations": [
        "No quantitative results (effect sizes, exact p-values) reported in the abstract beyond one significant MMN comparison",
        "Only male rats studied",
        "Exposure frequency stated (50 Hz) but detailed exposure regimen (e.g., hours/day) not provided in the abstract",
        "Mechanistic inference ('possibly induced by lipid peroxidation') is suggestive rather than demonstrated in the abstract"
    ],
    "evidence_strength": "low",
    "confidence": 0.7800000000000000266453525910037569701671600341796875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "extremely low-frequency",
        "ELF-EF",
        "50 Hz",
        "electric field",
        "mismatch negativity",
        "MMN",
        "event-related potentials",
        "ERP",
        "rats",
        "oxidative stress",
        "lipid peroxidation",
        "4-HNE",
        "protein carbonyl",
        "TUNEL",
        "apoptosis"
    ],
    "suggested_hubs": [
        {
            "slug": "animal-studies",
            "weight": 0.90000000000000002220446049250313080847263336181640625,
            "reason": "Rat experiment assessing neurophysiological and oxidative stress outcomes after ELF electric-field exposure."
        }
    ]
}

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