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

[自由行動ラットの大脳のアセチルコリン放出に対する低レベルラジオ周波数電磁界の影響] med./bio.

Effects of exposure to low level radiofrequency fields on acetylcholine release in hippocampus of freely moving rats

著者: Testylier G, Tonduli L, Malabiau R, Debouzy JC
掲載誌: Bioelectromagnetics 2002; 23 (4): 249-255
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この研究は、低強度の高周波電磁界への急性ばく露後のラットにおいて、脳内アセチルコリン（ACh）放出を調べた。ばく露中、ラットは自由行動させた。ばく露条件は、日中1時間の2.45 GHz連続波無線周波（RF）（2または4 mW / cm2）ばく露、または、夜間の1あるいは14時間の800 MHz変調波（32 Hz振幅変調、200 mW / cm2）ばく露である。海馬のCA1領域の上部に膜を固定した微小透析法により、Achの放出を測定した。その結果、2.45 GHz RFの場合、2 mW / cm2ばく露では、ラットのAch放出に有意な変化はなかったが、4 mW / cm2ばく露では、海馬からの平均ACh放出が有意に40 %低下した；この低下は、ばく露後5時間で最大になった；800 MHz変調波の場合、１時間ばく露では有意な変化は見られなかったが、14時間ばく露では、対照群と比較して、午後11時から午前4時の間のACh放出が有意に43 %低下した；対照群では、夜に入る時間帯でACh放出上昇が観察され、これはラットの覚醒期へ引き継がれるが、このような通常の上昇が、800 MHz変調波への一夜のばく露により妨げられた、と報告している。

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研究目的（著者による）

The authors used microdialysis to study acetylcholine (ACh) release in the hippocampus of freely moving rats after acute irradiation with two radiofrequency fields, using power density under permissible levels.

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
  • 電力密度: 2 mW/cm² unspecified
  • SAR: 3.26 W/kg average over mass (whole body)
  • 電力密度: 4 mW/cm² unspecified
  • SAR: 6.52 W/kg average over mass (whole body)
ばく露2: 800 MHz
Modulation type: AM
ばく露時間: continuous for 1 or 14 h
  • 電力密度: 0.2 mW/cm² unspecified
  • SAR: 0.325 W/kg average over mass (whole body)

ばく露1

主たる特性
周波数 2.45 GHz
タイプ
  • electromagnetic field
特性
  • near field
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
Distance between exposed object and exposure source 60 cm
チャンバの詳細 The rats were placed individually in a narrow Teflon cage (W 15 cm x L 30 cm x H 30 cm) with their main body axis parallel to the magnetic component of the field.
ばく露装置の詳細 The cage was positioned with its input face at 60 cm from the antenna and its bottom 5 cm under the axis.
Sham exposure A sham exposure was conducted.
Additional information The rectangular horn antennas had a horizontal great axis, so they emitted a horizontal magnetic component and a vertical electric component.
パラメータ
測定量 値 種別 Method Mass 備考
電力密度 2 mW/cm² unspecified 測定値 - -
SAR 3.26 W/kg average over mass 推定値 whole body -
電力密度 4 mW/cm² unspecified 測定値 - -
SAR 6.52 W/kg average over mass 推定値 whole body -
Additional parameter details

At 2.45 GHz, the cage was at the limit of the near field. The power density was maximal on the axis of the antenna and showed a uniform decrease with distance down to 30% at the edge of the cage.

測定および計算の詳細

At the beginning of exposures, field power density was measured at a reference point on the axis of the antenna at the input plane of the cage. A rough calculation of the SAR was performed using the formula: SAR (W/kg) = σE²/2ρ, where σ (Siemens/m) is the conductivity of brain tissue, ρ (kg/m³) its density and E (V/m) the electric field.

ばく露2

主たる特性
周波数 800 MHz
タイプ
  • electromagnetic field
特性
  • near field
ばく露時間 continuous for 1 or 14 h
Modulation
Modulation type AM
Modulation frequency 32 Hz
Additional information

[Kunjilwar and Behari, 1993]
ばく露装置
ばく露の発生源／構造
Distance between exposed object and exposure source 16 cm
ばく露装置の詳細 The cage was positioned with its input face at 16 cm from the antenna and its bottom 5 cm under the axis.
Sham exposure A sham exposure was conducted.
パラメータ
測定量 値 種別 Method Mass 備考
電力密度 0.2 mW/cm² unspecified 測定値 - -
SAR 0.325 W/kg average over mass 推定値 whole body -
Additional parameter details

The mean power density in the cage was 61 ± 25% SD of the indicated reference value.

測定および計算の詳細

At the beginning of exposures, field power density was measured at a reference point which was the midpoint of the bottom of the cage wall facing the antenna horn.

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:
研究対象とした臓器系:
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）

After exposure to 2.45 GHz radiofrequency, rats exposed at 2 mW/cm² did not show a significant modification of ACh release, whereas those exposed at 4 mW/cm² showed a significant 40% decrease in mean ACh release (this decrease was maximal at 5h post exposure). Irradiation to the 800 MHz radiofrequency for 1 h did not cause any significant effect, but exposure for 14 hours induced a significant 43% decrease in ACh release during the period 11 p.m.-4 a.m. compared to control rats. In the control group the authors observed an increase of ACh release at the beginning of the night, which was linked to the waking period of rats. The results indicate that neurochemical modification of the hippocampal cholinergic system can be observed during and after an exposure to low intensity radiofrequency.

研究の種別:

研究助成

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