Effects of extremely low frequency magnetic fields on pain thresholds in mice: roles of melatonin and opioids.

Journal of autonomic pharmacology · 2000 · Harm · Low evidence

← Research stream

HarmLow evidencePaper 3964

Study snapshot

PublicationJournal of autonomic pharmacology · 2000

Study typeanimal

Reported directionHarm

Evidence ratingLow

Abstract

1. We studied the effects of extremely low frequency (ELF, 60 Hz) magnetic fields (MFs) on pain thresholds using the hot plate test. The implication of opioid and benzodiazepine system in the MFs-induced alteration of pain thresholds was also studied. 2. There was an increase at night time and a decrease at daytime of pain thresholds in normal mice. Exposure of MFs (24 h, 20 gauss (G)) inhibited the increase of pain thresholds at night time and even produced hyperalgesia at daytime. 3. The increase of pain thresholds induced by melatonin at daytime was inhibited by exposure to MFs (24 h, 20 G) or opioid antagonist naloxone. The MFs and naloxone synergically inhibited hypoalgesia produced by melatonin. The hyperalgesia at daytime after MFs exposure was potentiated by the benzodiazepine agonist, diazepam, and inhibited by the benzodiazepine antagonist, flumazenil. There was no significant difference in all rotarod performance we tested. 4. From these results, it is suggested that exposure to MFs inhibits the increase of pain thresholds at night time and produces hyperalgesia at daytime with the involvement of opioid and benzodiazepine systems.

Machine Enhanced Logic

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 directionharm

PopulationMice

Sample sizeNot supplied

ExposureELF · 6e-05 MHz · 24 h

Evidence strengthLowConfidence: 74% · Peer reviewed: yes

Main findings

In normal mice, pain thresholds increased at night and decreased during daytime. Exposure to a 60 Hz magnetic field (20 G) for 24 h inhibited the nighttime increase in pain thresholds and produced hyperalgesia during daytime. Melatonin-induced increases in pain thresholds during daytime were inhibited by magnetic-field exposure or by naloxone, with magnetic-field exposure and naloxone showing synergic inhibition; daytime hyperalgesia after magnetic-field exposure was potentiated by diazepam and inhibited by flumazenil, while rotarod performance showed no significant differences.

Outcomes measured

Pain thresholds (hot plate test)
Hot plate hyperalgesia/hypoalgesia patterns (day vs night)
Effects/modulation by melatonin
Effects/modulation by naloxone (opioid antagonist)
Effects/modulation by diazepam (benzodiazepine agonist)
Effects/modulation by flumazenil (benzodiazepine antagonist)
Motor performance (rotarod)

Limitations

Sample size not reported in abstract
Exposure source/setup details not described beyond frequency, intensity, and duration
Animal study; generalizability to humans not addressed in abstract
Mechanistic conclusions (opioid/benzodiazepine involvement) are based on pharmacologic modulation as described in the abstract

View raw extracted JSON

{
  "study_type": "animal",
  "exposure": {
    "band": "ELF",
    "source": null,
    "frequency_mhz": 6e-05,
    "sar_wkg": null,
    "duration": "24 h"
  },
  "population": "Mice",
  "sample_size": null,
  "outcomes": [
    "Pain thresholds (hot plate test)",
    "Hot plate hyperalgesia/hypoalgesia patterns (day vs night)",
    "Effects/modulation by melatonin",
    "Effects/modulation by naloxone (opioid antagonist)",
    "Effects/modulation by diazepam (benzodiazepine agonist)",
    "Effects/modulation by flumazenil (benzodiazepine antagonist)",
    "Motor performance (rotarod)"
  ],
  "main_findings": "In normal mice, pain thresholds increased at night and decreased during daytime. Exposure to a 60 Hz magnetic field (20 G) for 24 h inhibited the nighttime increase in pain thresholds and produced hyperalgesia during daytime. Melatonin-induced increases in pain thresholds during daytime were inhibited by magnetic-field exposure or by naloxone, with magnetic-field exposure and naloxone showing synergic inhibition; daytime hyperalgesia after magnetic-field exposure was potentiated by diazepam and inhibited by flumazenil, while rotarod performance showed no significant differences.",
  "effect_direction": "harm",
  "limitations": [
    "Sample size not reported in abstract",
    "Exposure source/setup details not described beyond frequency, intensity, and duration",
    "Animal study; generalizability to humans not addressed in abstract",
    "Mechanistic conclusions (opioid/benzodiazepine involvement) are based on pharmacologic modulation as described in the abstract"
  ],
  "evidence_strength": "low",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "extremely low frequency",
    "ELF",
    "magnetic fields",
    "60 Hz",
    "20 gauss",
    "pain threshold",
    "hot plate test",
    "hyperalgesia",
    "melatonin",
    "opioids",
    "naloxone",
    "benzodiazepines",
    "diazepam",
    "flumazenil",
    "mice"
  ],
  "suggested_hubs": [
    {
      "slug": "animal-studies",
      "weight": 0.9,
      "reason": "Experimental study in mice assessing ELF magnetic-field effects on pain thresholds."
    }
  ]
}

AI can be wrong. Always verify against the paper.

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.1365-2680.2000.00189.x
PubMed: 11260364

Read the original paper →

Related papers

← Back to the Research Library