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

[PC12細胞でのHSP70発現およびMAPKシグナル伝達経路に対する間欠的1.8GHz無線周波電磁界ばく露の影響] med./bio.

Effects of the exposure to intermittent 1.8 GHz radio frequency electromagnetic fields on HSP70 expression and MAPK signaling pathways in PC12 cells

著者: Valbonesi P, Franzellitti S, Bersani F, Contin A, Fabbri E
掲載誌: Int J Radiat Biol 2014; 90 (5): 382-391
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この研究は、ラットPC12細胞にGSM電磁界ばく露を与え、細胞に引き起こされるストレス応答を評価した。ストレス応答は、熱ショックタンパク質70（HSP70）を介したものと、ニューロン様細胞においてマイトジェン活性化プロテインキナーゼ（MAPK）を介して生じるストレス応答を評価した。HSP70遺伝子発現レベルは逆転写酵素ポリメラーゼ連鎖反応で、HSP70タンパク質発現とMAPKリン酸化はウエスタンブロッティングで評価した。ばく露には、1.8 GHz連続波信号（CW、変調なしの搬送波周波数のみ）または2つの異なるGSM振幅変調方式（GSM-217HzおよびGSM-Talk（一般的な通話をシミュレートしたもの））を用いた。ばく露時間は4、16、または24時間、SARは2 W / kgとした。その結果、GSM-217Hz信号の16時間または24時間ばく露を受けた細胞で、HSP70転写レベルは有意に上昇した；一方、CWまたはGSM-Talk信号にばく露した細胞では影響は観察されなかった；HSP70タンパク質の発現および3つの異なるMAPKシグナル伝達経路は、3つの異なる1.8GHz信号のいずれのばく露によっても影響を受けなかった、と報告している。

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研究目的（著者による）

To investigate the stress responses mediated by Hsp70 and mitogen-activated protein kinases rat PC12 cells exposed to a 1.8 GHz-electromagnetic field.

詳細情報

In a previous study (Franzellitti et al., 2008 ), the authors reported the effects on the gene expression of Hsp70 in human trophoblast cells. In the present work, the same experimental conditions were applied but PC12 cells were used.
Cell cultures were subjected to one of the following conditions: 1.) sham exposure, 2.) exposure to a continuous wave, 3.) exposure to a GSM-217 Hz signal (simulates mobile phone speaking mode) and 4.) exposure to a GSM-217 Hz and GSM-DTX signal (simulates a typical mobile phone conversation with speaking and hearing). Cell cultures were exposed for 4, 16 or 24 hours. For every condition and time period, 6 experiments with 6 petri dishes were performed, respectively. Positive controls were performed (heat shock for Hsp70 gene expression, treatment with H2O2 for phosphorylation of mitogen-activated protein kinases).

影響評価項目

ばく露

ばく露 パラメータ
ばく露1: 1,800 MHz
Modulation type: CW
ばく露時間: intermittent, 5 min on/10 min off, for 4, 16, and 24 h
continuous wave
  • SAR: 2 W/kg average over time (± 0.4 W/kg)
ばく露2: 1,800 MHz
Modulation type: pulsed
ばく露時間: intermittent, 5 min on/10 min off, for 4, 16, and 24 h
GSM-217 Hz signal
  • SAR: 2 W/kg average over time (± 0.4 W/kg)
ばく露3: 1,800 MHz
Modulation type: pulsed
ばく露時間: intermittent, 5 min on/10 min off, for 4, 16, and 24 h
GSM-DTX signal + GSM-217 Hz signal
  • SAR: 2 W/kg average over time (± 0.4 W/kg)

ばく露1

主たる特性
周波数 1,800 MHz
タイプ
  • electromagnetic field
ばく露時間 intermittent, 5 min on/10 min off, for 4, 16, and 24 h
Additional information continuous wave
Modulation
Modulation type CW
ばく露装置
ばく露の発生源／構造
チャンバの詳細 The exposure system was developed and built following the specifications in [Schonborn et al., 2000]. Two 128.5 x 65 x 424 mm³ brass single-mode waveguide resonators equipped with ventilators and air temperature probes were placed inside one of the two incubators.
ばく露装置の詳細 Six 35-mm Petri dishes per resonator, each containing 3 ml of medium, were arranged in two stacks using a plastic holder and were placed in the H-field maximum of the standing wave (E-polarization).
Sham exposure A sham exposure was conducted.
Additional information Within each experiment, six dishes each were RF and sham exposed. Signal characteristics and the exposure/sham condition were assigned to the two waveguides by a computer-controlled signal unit ensuring blinded conditions.
パラメータ
測定量 値 種別 Method Mass 備考
SAR 2 W/kg average over time 測定値および計算値 - ± 0.4 W/kg
Additional parameter details

The temperature of the monolayer cells was uniformly distributed without localized "hot spots". The increase in temperature due to the exposure was well below 0.1°C per unit SAR. The temperature difference between sham and exposed cells was less than 0.1°C. The absolute uncertainty of the SAR was 20%, and the variation due to the nonuniformity was 28%. The temperature remained at 36.64 ± 0.12°C during the period of measurement, ensuring no thermal effects.

ばく露2

主たる特性
周波数 1,800 MHz
タイプ
  • electromagnetic field
波形
  • pulsed
ばく露時間 intermittent, 5 min on/10 min off, for 4, 16, and 24 h
Additional information GSM-217 Hz signal
Modulation
Modulation type pulsed
Duty cycle 12.5 %
Repetition frequency 217 Hz
Pulse type rectangular
Additional information

GSM-217 Hz signal (speaking only) with every 26th frame being idle, adding an 8 Hz modulation component [Pedersen, 1997]
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 値 種別 Method Mass 備考
SAR 2 W/kg average over time 測定値および計算値 - ± 0.4 W/kg

ばく露3

主たる特性
周波数 1,800 MHz
タイプ
  • electromagnetic field
ばく露時間 intermittent, 5 min on/10 min off, for 4, 16, and 24 h
Additional information GSM-DTX signal + GSM-217 Hz signal
Modulation
Modulation type pulsed
Duty cycle 12.5 %
Repetition frequency 217 Hz
Pulse type rectangular
Additional information

GSM-Talk signal (33% speaking and 67% hearing) with temporal changes between GSM-217 Hz and GSM-DTX (transmission reduced to 12 active frames per 104 frames) resulting in 2, 8, and 217 Hz modulation components
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 値 種別 Method Mass 備考
SAR 2 W/kg average over time 測定値および計算値 - ± 0.4 W/kg

Reference articles

  • Valbonesi P et al. (2008): [1.8 GHz振幅変調無線周波電磁界にばく露したヒト絨毛細胞株におけるHSP70発現とDNA損傷の評価]
  • Schuderer J et al. (2004): [1800 MHzのインビトロ実験に用いる強力なばく露および環境制御機能を備えた高尖頭SARばく露装置]
  • Kuster N et al. (2000): [無線通信に関係した健康リスクに着目した生物実験のばく露装置の最低限必要な条件とガイドライン]
  • Pedersen GF (1997): [GSM/DCS-1800電話から生じる振幅変調RF界]

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）

After 16 or 24 hours of exposure to the GSM-217 Hz signal (group 3), the gene expression of Hsp70 was significantly increased compared to the sham exposed cell cultures, while no significant effect was observed in the other exposure groups. Additionally, no differences between the groups were observed regarding protein expression levels and cell viability.
The authors conclude that the observed increase in the Hsp70 gene expression in PC12 cells confirmed the results of the previous study with trophoblasts.

研究の種別:

研究助成

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