Duration-dependent effect of exposure to static electric field on learning and memory ability in mice

Abstract

Duration-dependent effect of exposure to static electric field on learning and memory ability in mice Xu Y, Gu X, Di G. Duration-dependent effect of exposure to static electric field on learning and memory ability in mice. Environ Sci Pollut Res Int. 2018 Jun 7. Abstract With the rapid development of ultra-high-voltage direct-current (UHVDC) transmission, the strength of environmental static electric field (SEF) around UHVDC transmission lines increased substantially, which has aroused widely public attention on the potential health effects of SEF. In this study, the effect of SEF exposure on learning and memory ability was investigated. Institute of Cancer Research mice were exposed to 56.3 kV/m SEF for a short term (7 days) or long term (49 days). Behaviors in the Morris water maze (MWM) test, hippocampal neurotransmitter contents, and oxidative stress indicators were examined. Results showed that short-term SEF exposure significantly prolonged escape latency and decreased the number of platform-site crossovers, as well as decreased the time spent in the target quadrant in the MWM test. Meanwhile, serotonin level and the ratio of glutamate level to γ-aminobutyric acid level changed significantly. Besides, malondialdehyde content and glutathione peroxidase activity increased significantly, while superoxide dismutase activity decreased significantly. After long-term SEF exposure, all indices above showed no significant differences between the SEF and sham exposure groups. These data indicated that short-term exposure to 56.3 kV/m SEF could cause abnormal neurotransmitter levels and oxidative stress in the hippocampus, which led to the decline in learning and memory ability. Under the condition of long-term exposure, the SEF-induced disturbances in neurotransmitter contents and redox balance were offset by the compensatory responses of mice, and thus, the learning and memory ability returned to normal level. The temporary and reversible decline in learning and memory ability was only a common biological effect of SEF rather than a health hazard. ncbi.nlm.nih.gov

AI evidence extraction

Main findings

Mice exposed to a 56.3 kV/m static electric field for 7 days showed worse Morris water maze performance (prolonged escape latency, fewer platform-site crossovers, less time in target quadrant) along with significant changes in hippocampal serotonin and glutamate/GABA ratio and oxidative stress markers (increased malondialdehyde and glutathione peroxidase activity; decreased superoxide dismutase activity). After 49 days of exposure, these indices showed no significant differences versus sham.

Outcomes measured

• Learning and memory performance (Morris water maze: escape latency, platform-site crossovers, time in target quadrant)
• Hippocampal neurotransmitter contents (serotonin; glutamate/γ-aminobutyric acid ratio)
• Oxidative stress indicators (malondialdehyde, glutathione peroxidase activity, superoxide dismutase activity)

Limitations

• Sample size not reported in provided abstract/metadata
• Mechanistic interpretation (e.g., compensatory responses; not a health hazard) is asserted but not directly testable from the reported endpoints in the abstract

Suggested hubs

• occupational-exposure (0.32)
  Exposure context is static electric fields around UHVDC transmission lines, relevant to environmental/utility-line exposure scenarios.

{
    "study_type": "animal",
    "exposure": {
        "band": "other",
        "source": "ultra-high-voltage direct-current (UHVDC) transmission lines / environmental static electric field",
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": "7 days (short term) or 49 days (long term)"
    },
    "population": "Institute of Cancer Research mice",
    "sample_size": null,
    "outcomes": [
        "Learning and memory performance (Morris water maze: escape latency, platform-site crossovers, time in target quadrant)",
        "Hippocampal neurotransmitter contents (serotonin; glutamate/γ-aminobutyric acid ratio)",
        "Oxidative stress indicators (malondialdehyde, glutathione peroxidase activity, superoxide dismutase activity)"
    ],
    "main_findings": "Mice exposed to a 56.3 kV/m static electric field for 7 days showed worse Morris water maze performance (prolonged escape latency, fewer platform-site crossovers, less time in target quadrant) along with significant changes in hippocampal serotonin and glutamate/GABA ratio and oxidative stress markers (increased malondialdehyde and glutathione peroxidase activity; decreased superoxide dismutase activity). After 49 days of exposure, these indices showed no significant differences versus sham.",
    "effect_direction": "mixed",
    "limitations": [
        "Sample size not reported in provided abstract/metadata",
        "Mechanistic interpretation (e.g., compensatory responses; not a health hazard) is asserted but not directly testable from the reported endpoints in the abstract"
    ],
    "evidence_strength": "low",
    "confidence": 0.7399999999999999911182158029987476766109466552734375,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "static electric field",
        "UHVDC transmission",
        "mice",
        "learning and memory",
        "Morris water maze",
        "hippocampus",
        "serotonin",
        "glutamate",
        "GABA",
        "oxidative stress",
        "malondialdehyde",
        "glutathione peroxidase",
        "superoxide dismutase"
    ],
    "suggested_hubs": [
        {
            "slug": "occupational-exposure",
            "weight": 0.320000000000000006661338147750939242541790008544921875,
            "reason": "Exposure context is static electric fields around UHVDC transmission lines, relevant to environmental/utility-line exposure scenarios."
        }
    ]
}

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