研究のタイプ: 医学／生物学の研究 (experimental study)

[胚および出生後初期の超低周波磁界ばく露後のラットの脳スライスでのシナプス効率の変化] med./bio.

Changes in synaptic efficacy in rat brain slices following extremely low-frequency magnetic field exposure at embryonic and early postnatal age

著者: Balassa T, Varro P, Elek S, Drozdovszky O, Szemerszky R, Vilagi I, Bardos G
掲載誌: Int J Dev Neurosci 2013; 31 (8): 724-730
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この研究は、ラットの発達中の脳のシナプス機能に対するELF-MF（0.5および3 mT、50 Hz）の長期ばく露の影響を調べた。2つの実験を行った；1) 0.5 mT、1日24時間の子宮内ばく露を妊娠第2週の7日間継続、2) 3 mT、1日24時間のばく露を出生後3日目からの7日間継続。ばく露後、胎仔または新生仔の新皮質および海馬のスライス標本において、細胞外誘発電位を分析して、シナプスの興奮性と可塑性を検査した。その結果、海馬標本では、胎仔の0.5mTばく露および新生仔の3mTばく露の両方において、シナプスの興奮性増加が測定された；新皮質標本では、主に新生仔へのばく露で影響が見られ、興奮性シナプス後電位の振幅が増加した、などを報告している。

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研究目的（著者による）

To investigate the long-term effects of an exposure to extremely low frequency magnetic field on the synaptic functions in the developing rat brain.

詳細情報

Rats were exposed or sham exposed for 7 days: either in utero during the second week of pregnancy (sham exposure and exposure, each n=5)) or postnatal with the beginning of the third day after birth (n=6 sham exposure, n=6 exposure).
Rats were sacrificed in the age of two month and brain slices were examined. Altogether 32 neocortical and 31 hippocampal slices were tested (5-9 per group).

影響評価項目

ばく露

ばく露 パラメータ
ばく露1: 50 Hz
ばく露時間: continuous for 7 days during the second week of pregnancy
ばく露2: 50 Hz
ばく露時間: continuous for 7 days beginning with the third day after birth

ばく露1

主たる特性
周波数 50 Hz
タイプ
  • magnetic field
波形
  • sinusoidal
ばく露時間 continuous for 7 days during the second week of pregnancy
ばく露装置
ばく露の発生源／構造
ばく露装置の詳細 Helmholtz coil apparatus consisting of two solenoids with a radius of 21 cm each, 21 cm apart; homogenous vertical field in the space between the coils; coils constructed of 240 turns of glaze-insulated copper wire (d=1.4 mm); rats placed in 35 cm x 35 cm x 17 cm opaque plastic boxes in the center of the coils, temperature in boxes 24 ± 0.5°C
Sham exposure A sham exposure was conducted.
パラメータ
測定量 値 種別 Method Mass 備考
磁束密度 0.5 mT - 測定値 - ± 25 µT
Additional parameter details

ambient background level of magnetic field was <10 µT

ばく露2

主たる特性
周波数 50 Hz
タイプ
  • magnetic field
波形
  • sinusoidal
ばく露時間 continuous for 7 days beginning with the third day after birth
ばく露装置
ばく露の発生源／構造
  • E1と同じ装置
パラメータ
測定量 値 種別 Method Mass 備考
磁束密度 3 mT - 測定値 - -

ばく露を受けた生物:

方法 影響評価項目／測定パラメータ／方法

研究対象とした生物試料:
研究対象とした臓器系:
調査の時期:
  • ばく露後

研究の主なアウトカム（著者による）

Exposure during the pregnancy and exposure in the early postnatal age led to a significantly increased amplitude of evoked potentials in the hippocampal slices compared to the corresponding sham exposure group. Neocortical slices responded mostly to postnatal exposure. There, the amplitude of the excitatory postsynaptic potentials was significantly increased when compared to the sham exposure.
In neocortical sclices from sham exposed rats, typically paired-pulse depression appeared. However, an exposure during the pregnancy significantly inhibited the paired-pulse depression and significantly decreased the efficacy of long-term potentiation induction. No exposure effect on the paired-pulse depression and on the efficacy of the long-term potentiation induction was observed in hippocampal slices (exposed during pregnancy and postnatal) or in postnatal exposed rats in neocortical slices.
The authors conclude that exposure to extremely low frequency magnetic fields has an effect on basic synaptic functions and synaptic plasticity in the developing rat brain.

研究の種別:

研究助成

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