Effects of 50 Hz magnetic fields on circadian rhythm control in mice

2019 · Mixed · Low evidence

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MixedLow evidencePaper 1841

Study snapshot

Publicationmanual · 2019

Study typeanimal

Reported directionMixed

Evidence ratingLow

Abstract

Effects of 50 Hz magnetic fields on circadian rhythm control in mice Lundberg L, Sienkiewicz Z, Anthony DC, Broom KA. Effects of 50 Hz magnetic fields on circadian rhythm control in mice. Bioelectromagnetics. 2019 Apr 4. doi: 10.1002/bem.22188. Abstract Artificial light and power frequency magnetic fields are ubiquitous in the built environment. Light is a potent zeitgeber but it is unclear whether power frequency magnetic fields can influence circadian rhythm control. To study this possibility, 8-12-week-old male C57BL/6J mice were exposed for 30 min starting at zeitgeber time 14 (ZT14, 2 h into the dark period of the day) to 50 Hz magnetic fields at 580 μT using a pair of Helmholtz coils and/or a blue LED light at 700 lux or neither. Our experiments revealed an acute adrenal response to blue light, in terms of increased adrenal per1 gene expression, increased serum corticosterone levels, increased time spent sleeping, and decreased locomotor activity (in all cases, P < 0.0001) compared to an unexposed control group. There appeared to be no modulating effect of the magnetic fields on the response to light, and there was also no effect of the magnetic fields alone (in both cases, P > 0.05) except for a decrease in locomotor activity (P < 0.03). Gene expression of the cryptochromes cry1 and cry2 in the adrenals, liver, and hippocampus was also not affected by exposures (in all cases, P > 0.05). In conclusion, these results suggest that 50 Hz magnetic fields do not significantly affect the acute light response to a degree that can be detected in the adrenal response. ncbi.nlm.nih.gov

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AI evidence extraction

Structured fields below were generated from the paper’s abstract and metadata to make the evidence easier to inspect. Automated extraction may be incomplete or incorrect; verify important details against the original paper.

Study typeanimal

Effect directionmixed

Population8–12-week-old male C57BL/6J mice

Sample sizeNot supplied

ExposureELF · 0.05 MHz · 30 min starting at zeitgeber time 14 (ZT14)

Evidence strengthLowConfidence: 78% · Peer reviewed: yes

Main findings

Blue light exposure (700 lux) produced an acute adrenal response versus controls (increased adrenal per1 expression, increased serum corticosterone, increased time spent sleeping, and decreased locomotor activity; all P < 0.0001). The 50 Hz magnetic field exposure (580 µT) showed no modulating effect on the light response and no effect when applied alone (P > 0.05), except for a decrease in locomotor activity (P < 0.03). Cry1 and cry2 gene expression in adrenals, liver, and hippocampus was not affected by exposures (P > 0.05).

Outcomes measured

Adrenal per1 gene expression
Serum corticosterone levels
Time spent sleeping
Locomotor activity
Adrenal/liver/hippocampus cry1 gene expression
Adrenal/liver/hippocampus cry2 gene expression
Acute adrenal response to blue light
Circadian rhythm control (acute light response modulation)

Limitations

Sample size not reported in the provided abstract/metadata
Acute exposure only (30 min); no information on longer-term effects
Single mouse strain/sex/age group (male C57BL/6J, 8–12 weeks)
Single magnetic field intensity (580 µT) and timing (ZT14)
Endpoints focused on acute adrenal/light-response measures; broader circadian outcomes not described

View raw extracted JSON

{
  "study_type": "animal",
  "exposure": {
    "band": "ELF",
    "source": "other",
    "frequency_mhz": 0.05,
    "sar_wkg": null,
    "duration": "30 min starting at zeitgeber time 14 (ZT14)"
  },
  "population": "8–12-week-old male C57BL/6J mice",
  "sample_size": null,
  "outcomes": [
    "Adrenal per1 gene expression",
    "Serum corticosterone levels",
    "Time spent sleeping",
    "Locomotor activity",
    "Adrenal/liver/hippocampus cry1 gene expression",
    "Adrenal/liver/hippocampus cry2 gene expression",
    "Acute adrenal response to blue light",
    "Circadian rhythm control (acute light response modulation)"
  ],
  "main_findings": "Blue light exposure (700 lux) produced an acute adrenal response versus controls (increased adrenal per1 expression, increased serum corticosterone, increased time spent sleeping, and decreased locomotor activity; all P < 0.0001). The 50 Hz magnetic field exposure (580 µT) showed no modulating effect on the light response and no effect when applied alone (P > 0.05), except for a decrease in locomotor activity (P < 0.03). Cry1 and cry2 gene expression in adrenals, liver, and hippocampus was not affected by exposures (P > 0.05).",
  "effect_direction": "mixed",
  "limitations": [
    "Sample size not reported in the provided abstract/metadata",
    "Acute exposure only (30 min); no information on longer-term effects",
    "Single mouse strain/sex/age group (male C57BL/6J, 8–12 weeks)",
    "Single magnetic field intensity (580 µT) and timing (ZT14)",
    "Endpoints focused on acute adrenal/light-response measures; broader circadian outcomes not described"
  ],
  "evidence_strength": "low",
  "confidence": 0.78,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "50 Hz",
    "ELF magnetic fields",
    "580 µT",
    "circadian rhythm",
    "zeitgeber time",
    "blue light",
    "700 lux",
    "adrenal response",
    "per1",
    "corticosterone",
    "cry1",
    "cry2",
    "locomotor activity",
    "sleep",
    "mice",
    "Helmholtz coils"
  ],
  "suggested_hubs": [
    {
      "slug": "occupational-exposure",
      "weight": 0.2,
      "reason": "Study involves power-frequency (50 Hz) magnetic field exposure, relevant to ELF exposure contexts, though not explicitly occupational."
    }
  ]
}

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AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.

Identifiers and source

DOI: 10.1002/bem.22188
PubMed: Not supplied

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