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

[ラットの空間学習に対するマイクロ波と時間的非コヒーレント磁界の相互作用] med./bio.

Interaction of microwaves and a temporally incoherent magnetic field on spatial learning in the rat.

掲載誌: Physiol Behav 2004; 82 (5): 785-789

この研究は、著者らの作業仮説「時間的に非コヒーレントな磁界が、マイクロ波ばく露によってラット誘導される空間学習障害に影響を及ぼす」を実験的に検証した。著者は、時間的に非コヒーレントな磁界を「ノイズ」と称している。ラットは6回の訓練セッションで、円形の水迷路内に水没した架台の位置を特定する訓練を受けた。4群のラットは、訓練セッションの1時間前にそれぞれ次の条件のばく露を受けた:マイクロ波ばく露(2450 MHz連続波電力密度2 mW / cm2、平均全身SAR = 1.2 W / kg)、「ノイズばく露(60 mG )、マイクロ波+「ノイズばく露、および擬似ばく露である。最後の訓練セッションの1時間後、水中の架台を取り外した迷路で2分間の探索試行を行わせ、架台が置かれていた迷路の象限で2分間のうちに費やした時間を記録した。その結果、マイクロ波ばく露群は、擬似ばく露群に比べ、水中架台の位置特定の学習不足が有意であった;「ノイズばく露群の学習成績は、擬似ばく露群のものと同等であった;一方、マイクロ波+「ノイズばく露群の成績は、マイクロ波ばく露群のものより有意に改善されていた、と報告している。著者は、これらの知見から、時間的にインコヒーレントな磁界への同時ばく露は、マイクロ波によりラット誘導される空間学習記憶障害をブロックするという考察を述べている。

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研究目的(著者による)

To study the effect of a temporally incoherent magnetic field ('noise') on microwave-induced spatial learning deficit in the rat.

詳細情報

Rats were trained in six sessions to locate a submerged platform in a circular water maze. Four treatment groups were investigated: microwave-exposure, 'noise' exposure (60 mG), 'microwave + noise' exposure, and sham exposure.

影響評価項目

ばく露

ばく露 パラメータ
ばく露1: 2.45 GHz
Modulation type: CW
ばく露時間: continuous for 1 h
ばく露2: 30–100 Hz
ばく露時間: intermittent for 1 h
ばく露3: 2.45 GHz
Modulation type: CW
ばく露時間: continuous for 1 h

General information

Rats were arranged into four treatrment groups, 8 rats/group, which were arranged according the following treatment conditions: microwave exposure, microwave and noise exposure, noise exposure and sham exposure.

ばく露1

主たる特性
周波数 2.45 GHz
特性
  • guided field
偏波
  • circular
ばく露時間 continuous for 1 h
Modulation
Modulation type CW
ばく露装置
ばく露の発生源/構造
  • waveguides constructed of galvanized wire screen in TE11 mode
ばく露装置の詳細 A rat was placed in a cylindrical plastic chamber (19.6 cm long x 17.6 cm in diameter x 14.5 cm wide) situated inside the waveguides where it was able to move freely.
Sham exposure A sham exposure was conducted.
パラメータ
測定量 種別 Method Mass 備考
SAR 1.2 mW/g mean 指定なし whole body -
電力密度 20 W/m² mean 指定なし - -

ばく露2

主たる特性
周波数 30–100 Hz
タイプ
  • magnetic field
ばく露時間 intermittent for 1 h
Modulation
Modulation type cf. additional information
Additional information

The magnetic field was switched on and off during the exposure. The on/off pattern consisted of a repeating set of 660 alternating on and off intervals that cycled in approx. 11 mins. The duration of these intervals was chosen at random from a set of 11 time values which included 0.56 s, 1.67 s and values between separated by approx. 0.11 s.

ばく露装置
ばく露の発生源/構造
  • E1と同じ装置
ばく露装置の詳細 A waveguide containing a rat was placed between the coils but it was not activated.
Additional information The temporally incoherent magnetic field referred to as noise was generated using a signal recorded in an audio cassette tape. The tape was placed back in a continuous play cassette player connected to a power amplifier whose output was in turn connected to the coil.
パラメータ
測定量 種別 Method Mass 備考
磁束密度 6 µT mean 測定値 - -

ばく露3

主たる特性
周波数 2.45 GHz
特性
  • guided field
ばく露時間 continuous for 1 h
Additional information Simultaneous exposure to microwave and noise.
Modulation
Modulation type CW
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 種別 Method Mass 備考
磁束密度 6 µT mean 測定値 - -
電力密度 20 W/m² mean 指定なし - -
SAR 1.2 mW/g mean 指定なし whole body -

Reference articles

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:
調査の時期:
  • ばく露後

研究の主なアウトカム(著者による)

Data show that exposed rats had significant deficit in learning to locate the submerged platform when compared with the sham-exposed rats. Exposure to 'noise' alone did not significantly affect the performance of the rats: it was similar to that of the sham-exposed rats.
However, simultaneous exposure to 'noise' significantly attenuated the microwave-induced spatial learning deficit: 'microwave + noise'-exposed animals learned significantly better than the microwave-exposed rats.
During the probe trial, microwave-exposed rats spent significantly less time in the quadrant where the platform was located. However, response of the 'microwave + noise'-exposed rats was similar to that of the sham-exposed animals during the probe trial.
Thus, simultaneous irradiation to a temporally incoherent magnetic field blocks microwave-induced spatial learning and memory deficits in the rat.

研究の種別:

研究助成

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