The influences of extremely low frequency magnetic fields on clonidine-induced sleep in 2-day-old chicks.

Journal of autonomic pharmacology · 2001 · Mixed · Low evidence

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MixedLow evidencePaper 3881

Study snapshot

PublicationJournal of autonomic pharmacology · 2001

Study typeanimal

Reported directionMixed

Evidence ratingLow

Abstract

1. It has been shown that magnetic fields (MFs) affect a variety of biological effects in animal brains. There have been few experiments on the effects of MFs on sleep. Therefore, we investigated whether extremely low frequency (ELF) MFs affect the sleep induced by clonidine, a central alpha(2)-adrenoceptor agonist. Clonidine produced dose-related increase of the sleeping time and dose-related decrease of the onset time in 2-day-old chicks. 2. Exposure of chicks to MFs (5, 10, 20 G; for 3, 6, 9, 12 h) significantly increased the clonidine-induced sleep time as a direct function of intensity and duration of MF application. Clonidine reduced noradrenaline or tyrosine in the brain, an effect which was not further changed in animals exposed to MF. 3. To determine whether the gamma amino butyric acid A (GABA(A))/benzodiazepine (BZD) receptor system is involved in the decrease in clonidine-induced sleep caused by activation of central alpha(2)-adrenergic systems, we examined exposure of chicks to the effects of the BZD receptor antagonist flumazenil (0.5 mg kg(-1), i.p.) and GABA(A) antagonist bicuculline (0.1 mg kg-1, i.p.) on clonidine-induced sleep. Bicuculline and flumazenil inhibited the increase of clonidine-induced sleep time by MFs. Clonidine or MFs did not change GABA levels in the brain. 4. These results suggest that MFs can increase clonidine-induced sleep via a change of GABA(A) and BZD receptor system irrespective of the concentration of GABA or noradrenaline in the brain of 2-day-old chicks.

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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

Population2-day-old chicks

Sample sizeNot supplied

ExposureELF · 3, 6, 9, 12 h

Evidence strengthLowConfidence: 74% · Peer reviewed: yes

Main findings

Exposure to extremely low frequency magnetic fields (5, 10, 20 G for 3–12 h) significantly increased clonidine-induced sleep time in 2-day-old chicks as a function of field intensity and exposure duration. Clonidine reduced brain noradrenaline or tyrosine, and this effect was not further changed by magnetic field exposure. Bicuculline and flumazenil inhibited the magnetic-field-associated increase in clonidine-induced sleep time, while clonidine or magnetic fields did not change brain GABA levels.

Outcomes measured

Clonidine-induced sleep time
Sleep onset time
Brain noradrenaline
Brain tyrosine
Brain GABA levels
Effects of flumazenil (BZD receptor antagonist) and bicuculline (GABA(A) antagonist) on clonidine-induced sleep under MF exposure

Limitations

Sample size not reported in abstract
ELF magnetic field frequency not specified
Outcomes are pharmacologically induced sleep in an animal model; generalizability to natural sleep or humans is unclear from abstract
Mechanistic conclusions are suggestive; receptor involvement inferred from antagonist effects

View raw extracted JSON

{
  "study_type": "animal",
  "exposure": {
    "band": "ELF",
    "source": null,
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": "3, 6, 9, 12 h"
  },
  "population": "2-day-old chicks",
  "sample_size": null,
  "outcomes": [
    "Clonidine-induced sleep time",
    "Sleep onset time",
    "Brain noradrenaline",
    "Brain tyrosine",
    "Brain GABA levels",
    "Effects of flumazenil (BZD receptor antagonist) and bicuculline (GABA(A) antagonist) on clonidine-induced sleep under MF exposure"
  ],
  "main_findings": "Exposure to extremely low frequency magnetic fields (5, 10, 20 G for 3–12 h) significantly increased clonidine-induced sleep time in 2-day-old chicks as a function of field intensity and exposure duration. Clonidine reduced brain noradrenaline or tyrosine, and this effect was not further changed by magnetic field exposure. Bicuculline and flumazenil inhibited the magnetic-field-associated increase in clonidine-induced sleep time, while clonidine or magnetic fields did not change brain GABA levels.",
  "effect_direction": "mixed",
  "limitations": [
    "Sample size not reported in abstract",
    "ELF magnetic field frequency not specified",
    "Outcomes are pharmacologically induced sleep in an animal model; generalizability to natural sleep or humans is unclear from abstract",
    "Mechanistic conclusions are suggestive; receptor involvement inferred from antagonist effects"
  ],
  "evidence_strength": "low",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "extremely low frequency",
    "magnetic fields",
    "ELF",
    "clonidine",
    "sleep",
    "chicks",
    "GABA(A)",
    "benzodiazepine receptor",
    "flumazenil",
    "bicuculline",
    "noradrenaline",
    "tyrosine"
  ],
  "suggested_hubs": []
}

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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: 10.1046/j.1365-2680.2001.00227.x
PubMed: 11952875

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