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

[ラット乳腺におけるストレスマーカーα-アミラーゼへの50 Hz磁界ばく露の影響] med./bio.

Effects of 50 Hz magnetic field exposure on the stress marker alpha-amylase in the rat mammary gland.

掲載誌: Int J Radiat Biol 2012; 88 (7): 556-564

著者らは、以前に、乳腺細胞増殖および腫瘍成長に対する50/60磁界ばく露の影響がラット系統によって異なることを見出し、これは、メカニズムは不明であるが、(エピ)ジェニックな要素が影響していることを示しているのかも知れないと考えている。今回の実験は、ストレス感受性の異なる系統であるF344ラットとLewisラット乳腺におけるα-アミラーゼ(ヒトでのストレスマーカーとして知られる)を指標に、系統の差による磁界(50 Hz, 100 μT)の影響の差を調べた。F344雌ラット158匹とLewisラット36匹をそれぞればく露群と擬似ばく露群に分け、ばく露時間によってさらに細分化した。50 Hz, 100 μT への24時間ばく露を、F344ラットでは1、7、14、28日間、Lewisラットでは14日間のみ行った。ばく露後、頭側の第一番目からから尾側の5番目までの左右の乳腺組織を摘出して分析した結果、14、28日間ばく露のF344ラット乳腺においてα-アミラーゼが有意に上昇したが、Lewisラットでは何も影響が見られなかったことを報告し、ヒトや細胞での磁界感受性のバイオマーカーとしてα-アミラーゼの可能性を議論している。

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研究目的(著者による)

To study the functionality and expression of alpha-amylase in the breast tissue of Fischer 344 rats as well as serum enzyme activity after magnetic field exposure. For some experiments, Lewis rats were included and compared to Fischer 344 rats.

詳細情報

Fischer 344 rats and Lewis rats are two strains with distinct stress sensitivity and magnetic field susceptibility. Fischer 344 rats show higher corticosterone and ACTH levels after stress than Lewis rats. In a previous study (Fedrowitz and Löscher 2012), a gene expression analysis in the mammary gland revealed a marked alteration of alpha-amylase in magnetic field exposed Fischer 344 rats but not in Lewis rats. These data prompted the authors to investigate the magnetic field effects on alpha-amylase in more detail.
For comparison with the magnetic field effects on alpha-amylase activity, diethylstilbestrol (DES; an estrogen-like acting substance, which stimulates proliferation and differentiation in the mammary gland tissue) was applied to Fischer 344 rats to investigate alpha-amylase in breast tissue under estrogenic influence.
158 female Fischer 344 rats and 36 Lewis rats at an age of 42-45 days were used in 10 independent experiments over a time period of four years.

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 1 day, 7, 14 and 28 days (24 h/day; except time for weighing and cage cleaning)
Fischer 344 rats
ばく露2: 50 Hz
ばく露時間: continuous for 14 days (24 h/day; except time for weighing and cage cleaning)
Lewis rats

ばく露1

主たる特性
周波数 50 Hz
タイプ
  • magnetic field
ばく露時間 continuous for 1 day, 7, 14 and 28 days (24 h/day; except time for weighing and cage cleaning)
Additional information Fischer 344 rats
ばく露装置
ばく露の発生源/構造
ばく露装置の詳細 rats were exposed in groups of 5-10 animals; controlled conditions of temperature (23-24°C), humidity (about 50%) and light (12 h dark/light cycle) and free access to food and water
Sham exposure A sham exposure was conducted.
パラメータ
測定量 種別 Method Mass 備考
磁束密度 100 µT - 測定値 - -

ばく露2

主たる特性
周波数 50 Hz
タイプ
  • magnetic field
ばく露時間 continuous for 14 days (24 h/day; except time for weighing and cage cleaning)
Additional information Lewis rats
ばく露装置
ばく露の発生源/構造
  • E1と同じ装置
Sham exposure A sham exposure was conducted.
パラメータ
測定量 種別 Method Mass 備考
磁束密度 100 µT - 測定値 - -

Reference articles

  • Baum A et al. (1995): [DMBAで誘導したラットの乳がん発がんにおける50 Hz、100μT磁界ばく露の影響についての組織病理学的研究]

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:
  • mammary gland
調査の時期:
  • ばく露中
  • ばく露後

研究の主なアウトカム(著者による)

In the first set of experiments, alpha-amylase enzyme activity was significantly enhanced in the Fischer 344 and Lewis rats cranial mammary gland complexes after two weeks of magnetic field exposure as well as after 28 days in Fischer 344 rats without any alterations in the caudal mammary gland complexes. In a second set of experiments, a moderate, but statistically significant increase in enzyme activity was found in the caudal mammary gland complexes in Fischer 344 rats after 14 days of exposure, but not in Lewis rats.
In one of the two sets of experiments, protein expression of alpha-amylase was significantly elevated in caudal mammary gland complexes after magnetic field exposure for 14 days, but not in the cranial mammary gland complexes.
There were no significant differences in the alpha-amylase enzyme activity in serum between sham exposed and magnetic field exposed rats after 1, 7 and 14 days.
Although alpha-amylase represents a difficult parameter in animal studies because of its stress sensitivity, it should be considered for investigations of magnetic field effects in humans as a marker for stress and as a target to examine possible magnetic field mechanisms.

研究の種別:

研究助成

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