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

[カミキリムシの触角葉のニューロン集団活動に対する静磁界およびELF磁界の影響のウェーブレット解析] med./bio.

Effects of the static and ELF magnetic fields on the neuronal population activity in Morimus funereus (Coleoptera, Cerambycidae) antennal lobe revealed by wavelet analysis.

掲載誌: Comp Biochem Physiol A Mol Integr Physiol 2015; 181: 27-35

この研究は、カミキリムシ(Coleoptera, Cerambycidae)の成虫に、静磁界SMF:2 mT)およびELF磁界(ELF MF:50Hz、2 mT)のばく露を与え、触角葉でのニューロン集団活動を表す局所フィールド電位(LFPs)を測定して、ウェーブレット解析した。その結果、ELF MFばく露では、正弦波または方形波で、対照群に比べ、4-8Hz帯の相対ウェーブレットエネルギー(RWE)が有意に上昇し、1-2Hz帯のRWEが有意に減少した;64-128Hz帯のRWEが方形波で減少した;SMFでは、5分間ばく露で何の変化も見られなかった、と報告している。

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研究目的(著者による)

To investigate the effect of a static magnetic field and of extremely low frequency magnetic fields on the neuronal population activity in the antennal lobe (part of the insect brain which receives the input from the olfactory sensory neurons on the antenna) of beetles.

詳細情報

The species Morimus funereus is classified as "vulnerable" by the International Union for Conservation of Nature and Natural Resources (IUCN). Hence, it is important to understand how different ecological factors such as magnetic fields could affect the nervous system of this beetle.
An additional goal of this study was to test whether the wavelet transformation is suitable to measure the potential exposure induced effects on the neuronal population activity of insects.
Three experiments were conducted: 1.) exposure to a static magnetic field (n=7), 2.) exposure to a sine wave 50 Hz magnetic field (n=12) and 3.) exposure to a square wave 50 Hz magnetic field (n=10). In the first experiment, a 5 minutes baseline was recorded before the exposure period, followed by a 5 minutes recording during exposure and a 5 minutes after-exposure recording. The experiments 2 and 3 consisted of 3 exposure sessions with exposure durations of 5, 10, and 15 minutes. Recordings were performed 5 minutes before the first exposure (baseline) as well as immediately after the first exposure period (5 min) and 35 min later. Immediately after the "35 minutes later recording" started the next exposure period (10 min) and 35 min later the next recording. Subsequently, a 15 min exposure period started, which was 35 min later followed by the last recording.

影響評価項目

ばく露

ばく露 パラメータ
ばく露1:
  • DC/static
ばく露時間: continuous for 5 minutes
ばく露2: 50 Hz
ばく露時間: continuous for 5, 10, and 15 minutes
sine wave
ばく露3: 50 Hz
ばく露時間: continuous for 5, 10, and 15 minutes
square wave

ばく露1

主たる特性
周波数
  • DC/static
タイプ
  • magnetic field
ばく露時間 continuous for 5 minutes
ばく露装置
ばく露の発生源/構造
  • electromagnet
ばく露装置の詳細 magnetic field was produced by an electromagnet, powered by a DC voltage source of 12 V; magnet was placed at a distance of 2 cm from the left antenna
パラメータ
測定量 種別 Method Mass 備考
磁束密度 2 mT mean 測定値 - at head surface

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 5, 10, and 15 minutes
Additional information sine wave
ばく露装置
ばく露の発生源/構造
Distance between exposed object and exposure source 1 cm
ばく露装置の詳細 magnetic field was generated by a Teflon coil (length 70 mm, diameter 30 mm) which was coiled by enameled copper wire; a soft iron core (diameter of 8 mm) was placed in the middle of the cylinder, so it represents a single unit; magnet was connected to the power amplifier and the frequency generator, which enabled generation of different waveforms; sine wave and square wave current (0.3 A, 12 V, 50 Hz) flows through the magnet inducing MF of 19 mT on the top of the core; an oscilloscope was used to check the waveform accuracy; magnet was placed 1 cm from the left antenna of the beetle
パラメータ
測定量 種別 Method Mass 備考
磁束密度 2 mT mean 測定値 - at head surface

ばく露3

主たる特性
周波数 50 Hz
タイプ
  • magnetic field
波形
  • rectangular
ばく露時間 continuous for 5, 10, and 15 minutes
Additional information square wave
Additional information rise time of the square was about 2.2 ms, the root mean of the amplitude of the square signal was 630 mV, width of impulses was 5 ms, and period was 20 ms
ばく露装置
ばく露の発生源/構造
  • same setup as in E2
Distance between exposed object and exposure source 1 cm
パラメータ
測定量 種別 Method Mass 備考
磁束密度 2 mT mean 測定値 - at head surface

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:
  • insect brain
調査の時期:
  • ばく露前
  • ばく露中
  • ばく露後

研究の主なアウトカム(著者による)

No significant influence of the static magnetic field on the neuronal population activity in the antennal lobe was observed.
Exposure to extremely low frequency magnetic fields induced significant changes in the slow (1-2 Hz, 4-8 Hz) and in the fast (64-128 Hz) frequency bands of the local field potentials from the antennal lobe compared to the corresponding baseline: In the second experiment (sine wave), the relative wavelet energy in the range of 1-2 Hz was significantly decreased after the repeated and prolonged exposures, while it was increased in the 4-8 Hz frequency band immediately after the first exposure as well as after repeated exposures. In the third experiment (square wave), the relative wavelet energy of the 4-8 Hz frequency band was significantly increased immediately after the first exposure as well as after repeated exposures. In the 1-2 Hz range, the relative wavelet energy was significantly decreased only after repeated exposures and in the 64-128 Hz range it was significantly decreased immediately after the first exposure and after repeated exposures.
The authors conclude that extremely low frequency magnetic fields could affect the neuronal population activity in the antennal lobe of Morimus funereus and that wavelet transformation presents a valuable tool for measuring these changes.

研究の種別:

研究助成

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