Blood-brain barrier and electromagnetic fields: effects of scopolamine methylbromide on working memory after whole-body exposure to 2.45 GHz microwaves in rats.

Behavioural brain research · 2005 · No effect · Low evidence

← Research stream

No effectLow evidencePaper 5179

Study snapshot

PublicationBehavioural brain research · 2005

Study typeanimal

Reported directionNo effect

Evidence ratingLow

Abstract

We first verified that our 12-arm radial maze test enabled demonstration of memory deficits in rats treated with the muscarinic antagonist scopolamine hydrobromide (0.5mg/kg, i.p.). We then investigated whether a systemically-injected quaternary-ammonium derivate of this antagonist (scopolamine methylbromide; MBR), which poorly crosses the blood-brain barrier (BBB), altered maze performance after a 45-min exposure to 2.45 GHz electromagnetic field (EMF; 2 micros pulse width, 500 pps, whole-body specific energy absorption rate [SAR] of 2.0 W/kg, +/-2dB and brain averaged SAR of 3.0 W/kg, +/-3 dB); if observed, such an alteration would reflect changes in BBB permeability. The drug was injected before or after exposure. Controls were naive rats (no experience of the exposure device) and sham-exposed rats (experience of the exposure device without microwaves). In a final approach, rats were subjected to i.v. injections of Evans blue, a dye binding serum albumin, before or after EMF exposure. Whether scopolamine MBR was injected before or after exposure, the exposed rats did not perform differently from their naive or sham-exposed counterparts. Thus, EMFs most probably failed to disrupt the BBB. This conclusion was further supported by the absence of Evans blue extravasation into the brain parenchyma of our exposed rats.

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 directionno_effect

PopulationRats

Sample sizeNot supplied

Exposuremicrowave · 2450 MHz · 2 W/kg · 45 min

Evidence strengthLowConfidence: 78% · Peer reviewed: yes

Main findings

After 45-min whole-body exposure to a 2.45 GHz EMF (whole-body SAR 2.0 W/kg; brain-averaged SAR 3.0 W/kg), rats injected with scopolamine methylbromide before or after exposure did not differ in maze performance from naive or sham-exposed controls. No Evans blue extravasation into brain parenchyma was observed, supporting no detectable BBB disruption under these conditions.

Outcomes measured

Working memory performance in 12-arm radial maze
Blood-brain barrier (BBB) permeability inferred from scopolamine methylbromide effects
Evans blue extravasation into brain parenchyma

Limitations

Sample size not reported in the provided abstract/metadata
Findings are from a rat model; generalizability to humans is not addressed in the abstract
Exposure parameters are specific (2.45 GHz, 45 min, SAR as stated); other exposure conditions were not evaluated in the abstract

View raw extracted JSON

{
  "study_type": "animal",
  "exposure": {
    "band": "microwave",
    "source": null,
    "frequency_mhz": 2450,
    "sar_wkg": 2,
    "duration": "45 min"
  },
  "population": "Rats",
  "sample_size": null,
  "outcomes": [
    "Working memory performance in 12-arm radial maze",
    "Blood-brain barrier (BBB) permeability inferred from scopolamine methylbromide effects",
    "Evans blue extravasation into brain parenchyma"
  ],
  "main_findings": "After 45-min whole-body exposure to a 2.45 GHz EMF (whole-body SAR 2.0 W/kg; brain-averaged SAR 3.0 W/kg), rats injected with scopolamine methylbromide before or after exposure did not differ in maze performance from naive or sham-exposed controls. No Evans blue extravasation into brain parenchyma was observed, supporting no detectable BBB disruption under these conditions.",
  "effect_direction": "no_effect",
  "limitations": [
    "Sample size not reported in the provided abstract/metadata",
    "Findings are from a rat model; generalizability to humans is not addressed in the abstract",
    "Exposure parameters are specific (2.45 GHz, 45 min, SAR as stated); other exposure conditions were not evaluated in the abstract"
  ],
  "evidence_strength": "low",
  "confidence": 0.78,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "blood-brain barrier",
    "BBB permeability",
    "2.45 GHz",
    "microwave",
    "EMF",
    "whole-body exposure",
    "specific absorption rate",
    "SAR",
    "working memory",
    "radial arm maze",
    "scopolamine methylbromide",
    "Evans blue",
    "rats"
  ],
  "suggested_hubs": []
}

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: 10.1016/j.bbr.2005.02.025
PubMed: 15922049

Read the original paper →

Related papers

← Back to the Research Library