Tempol suppresses micronuclei formation in astrocytes of newborn rats exposed to 50-Hz, 10-mT electromagnetic fields under bleomycin administration.

Abstract

A number of epidemiological studies have suggested that exposure to environmental and occupational electromagnetic fields (EMFs) contribute to the induction of brain tumors. The aim of this study was to investigate the mutagenetic effects of co-exposure to 50-Hz, 10-mT EMFs and bleomycin (BLM) using an ex vivo newborn rat astrocyte micronucleus assay. We also investigated whether the mutagenetic effects of EMFs were related to active oxygen species by using 4-hydroxy-2,2,6,6-tetramethyl piperidine-1-oxyl (tempol), a superoxide radical scavenger. Three-day-old male Sprague-Dawley rats were co-exposed to 50-Hz EMFs and BLM (5 or 10mg/kg body weight (BW)) in each group (n=6; total 6 group), and were co-exposed to 50-Hz EMFs and 10mg/kg BW BLM with administration of 200μmol/kg BW tempol in each group (total 4 group). Brain cells were dissociated into single cells, cultured for 96h, incubated with an antibody against glial fibrillary acidic protein, and stained with acridine orange. The frequency of micronucleated astrocytes was determined using a fluorescence microscope. The frequency of micronucleated astrocytes in the 10mg/kg BW bleomycin plus EMF exposure group (Mean±SD: 19.8±5.2‰) was 1.6 times higher than that in the 10mg/kg BW bleomycin plus sham-exposure group (Mean±SD: 12.7±3.3‰) (p<0.05). Analysis of the frequency of micronuclei in astrocytes after co-exposure to EMF and bleomycin for 72h and administration of tempol revealed that, in the EMF exposure group, the frequency of micronuclei in rats administered with 10mg/kg BW bleomycin and treated with tempol (Mean±SD: 11.2±1.9‰) was 40% of that in rats administered with the same dose of bleomycin and physiological saline (Mean±SD: 28.0±15.0‰) (p<0.01). Results of the current study suggested that the mechanism responsible for the elevated frequency of micronuclei in astrocytes of rats co-exposed to BLM and EMFs is related to active oxygen species.

AI evidence extraction

Main findings

In newborn rats given bleomycin (10 mg/kg BW), co-exposure to 50-Hz, 10-mT EMF increased micronucleated astrocyte frequency versus sham (19.8±5.2‰ vs 12.7±3.3‰; p<0.05). With tempol during EMF + bleomycin co-exposure, micronuclei frequency was lower than with saline (11.2±1.9‰ vs 28.0±15.0‰; p<0.01).

Outcomes measured

• Micronucleated astrocyte frequency (micronucleus assay)
• Effect of tempol (superoxide radical scavenger) on micronuclei frequency under EMF + bleomycin co-exposure

Limitations

• Ex vivo assay in dissociated/cultured brain cells rather than in vivo tumor outcomes
• Co-exposure design with bleomycin; effects of EMF alone not described in the abstract
• Small group size reported (n=6) and multiple groups; total sample size not clearly stated

Suggested hubs

• occupational-exposure (0.2)
  Abstract references environmental and occupational EMF context, though the experiment is in animals.

{
    "study_type": "animal",
    "exposure": {
        "band": "ELF",
        "source": "other",
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": "Co-exposure for 72 h (micronuclei analysis mentioned after 72 h); cells cultured for 96 h"
    },
    "population": "Three-day-old male Sprague-Dawley newborn rats; ex vivo astrocytes (brain cells dissociated and cultured)",
    "sample_size": 6,
    "outcomes": [
        "Micronucleated astrocyte frequency (micronucleus assay)",
        "Effect of tempol (superoxide radical scavenger) on micronuclei frequency under EMF + bleomycin co-exposure"
    ],
    "main_findings": "In newborn rats given bleomycin (10 mg/kg BW), co-exposure to 50-Hz, 10-mT EMF increased micronucleated astrocyte frequency versus sham (19.8±5.2‰ vs 12.7±3.3‰; p<0.05). With tempol during EMF + bleomycin co-exposure, micronuclei frequency was lower than with saline (11.2±1.9‰ vs 28.0±15.0‰; p<0.01).",
    "effect_direction": "harm",
    "limitations": [
        "Ex vivo assay in dissociated/cultured brain cells rather than in vivo tumor outcomes",
        "Co-exposure design with bleomycin; effects of EMF alone not described in the abstract",
        "Small group size reported (n=6) and multiple groups; total sample size not clearly stated"
    ],
    "evidence_strength": "low",
    "confidence": 0.7800000000000000266453525910037569701671600341796875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "ELF-EMF",
        "50-Hz",
        "10 mT",
        "newborn rats",
        "Sprague-Dawley",
        "astrocytes",
        "micronucleus assay",
        "micronuclei",
        "bleomycin",
        "tempol",
        "oxidative stress",
        "active oxygen species",
        "genotoxicity"
    ],
    "suggested_hubs": [
        {
            "slug": "occupational-exposure",
            "weight": 0.200000000000000011102230246251565404236316680908203125,
            "reason": "Abstract references environmental and occupational EMF context, though the experiment is in animals."
        }
    ]
}

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