Analysis of DNA fragmentation in mouse embryos exposed to an extremely low-frequency electromagnetic field.

Abstract

Effects of extremely low-frequency electromagnetic fields (ELF-EMFs) on DNA damage in biological systems are still a matter of dispute. The aim of the present study was to investigate the possible effect of electromagnetic field exposure on DNA fragmentation in cells (blastomers) of mouse blastocysts. Eighty female NMRI mice were randomly divided into 2 groups of 40 animals each. The control group was left unexposed whereas the animals in the EMF-group were exposed to a 50-Hz EMF at 0.5 mT 4 h per day, 6 days a week for a duration of 2 weeks. After the 8(th) day of exposure, the female mice in both groups were superovulated (with injections of pregnant mare serum gonadotropin and human chorionic gonadotropin) and then mated overnight. At approximately 4 days after mating (102 h after the human chorionic gonadotropin treatment), blastocysts were obtained by flushing the uterus horns. The mean numbers of pregnant mice, blastocysts after flushing, blastomers within the blastocysts, and the DNA fragmentation index following staining in both groups were compared using statistical methods (SPSS, the Chi-square test, the Student's t-test and the Mann-Whitney U-test, P < 0.05). The results showed that the mean number of blastocysts after flushing was significantly decreased in the EMF-group compared to that of the control group (P < 0.03). The DNA fragmentation index was significantly increased in the EMF-group compared to control (10.53% vs. 7.14%; P < 0.001). However, there was no significant difference in the mean numbers of blastomers and numbers of pregnant mice between the EMF-exposed and control group. Our findings indicate that the EMF exposure in preimplantation stage could have detrimental effects on female mouse fertility and embryo development by decreasing the number of blastocysts and increasing the blastocysts DNA fragmentation.

AI evidence extraction

Main findings

EMF exposure significantly decreased the number of blastocysts and increased DNA fragmentation index in blastocysts compared to control. No significant difference was found in the number of blastomers or pregnant mice between groups.

Outcomes measured

• number of blastocysts after flushing
• DNA fragmentation index in blastocysts
• number of blastomers within blastocysts
• number of pregnant mice

Limitations

• Study conducted in mice, limiting direct applicability to humans
• Exposure parameters specific and may not represent typical human exposures
• No long-term fertility outcomes assessed

Suggested hubs

• occupational-exposure (0.6)
  Study of ELF-EMF biological effects relevant to occupational exposure levels
• who-icnirp (0.4)
  Addresses DNA damage potentially relevant to exposure guidelines

{
    "study_type": "randomized_trial",
    "exposure": {
        "band": "ELF",
        "source": null,
        "frequency_mhz": 0.05000000000000000277555756156289135105907917022705078125,
        "sar_wkg": null,
        "duration": "4 hours per day, 6 days a week, for 2 weeks"
    },
    "population": "female NMRI mice",
    "sample_size": 80,
    "outcomes": [
        "number of blastocysts after flushing",
        "DNA fragmentation index in blastocysts",
        "number of blastomers within blastocysts",
        "number of pregnant mice"
    ],
    "main_findings": "EMF exposure significantly decreased the number of blastocysts and increased DNA fragmentation index in blastocysts compared to control. No significant difference was found in the number of blastomers or pregnant mice between groups.",
    "effect_direction": "harm",
    "limitations": [
        "Study conducted in mice, limiting direct applicability to humans",
        "Exposure parameters specific and may not represent typical human exposures",
        "No long-term fertility outcomes assessed"
    ],
    "evidence_strength": "moderate",
    "confidence": 0.6999999999999999555910790149937383830547332763671875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "ELF-EMF",
        "DNA fragmentation",
        "mouse embryos",
        "blastocysts",
        "fertility",
        "embryo development"
    ],
    "suggested_hubs": [
        {
            "slug": "occupational-exposure",
            "weight": 0.59999999999999997779553950749686919152736663818359375,
            "reason": "Study of ELF-EMF biological effects relevant to occupational exposure levels"
        },
        {
            "slug": "who-icnirp",
            "weight": 0.40000000000000002220446049250313080847263336181640625,
            "reason": "Addresses DNA damage potentially relevant to exposure guidelines"
        }
    ]
}

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