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

[弱い複合磁界と薬剤との相互作用による熱刺激に対する鎮痛効果] med./bio.

Thermal analgesic effects from weak, complex magnetic fields and pharmacological interactions.

掲載誌: Pharmacol Biochem Behav 2004; 78 (2): 217-227

この研究は、雄ラットを用いた実験で、弱い(1 μT)複雑な磁界へのばく露後に熱刺激を与え、その刺激に対する鎮痛効果を測定した。その結果、バースト発火のような構成の磁界の約4秒に1回のパターンでの30分間ばく露で鎮痛効果が生じた;鎮痛効果は強度に依存していた;異なる周波数変調パターンにより、鎮痛効果はより迅速に生じた;バースト発火磁界へのばく露後の鎮痛効果は、モルヒネ(4 mg / kg)またはアグマチン(10 mg / kg)の事前注射によって顕著に増強されたが、ナロキソン(1 mg / kg)によって阻害された、と報告している。

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研究目的(acc. to editor)

To study thermal analgesic effects from weak, complex magnetic fields and pharmacological interactions in rats.

詳細情報

Rats were placed on a thermal plate that was maintained at 55°C. Once the rat was observed to lick one hind feet twice, the rat was removed from the apparatus.
Several experiments were performed: 1) electrical versus thermal analgesia; 2) intensity dependence of analgesia (exposure to 3 µT (the usual), 0.3 µT, or about 30 nT); 3) spatial parameters of field (usual field parameters or the same field condition within a Helmholtz coil); 4) comparison of two complex patterns (the efficacy of a frequency modulated pattern was compared with the typical burst-firing pattern); 5) verifying the specifity of experiment 4; 6) interactions between two types of magnetic fields (burst-firing magnetic field and frequency modulated magnetic field) and morphine (4 mg/kg) or agmatine (10 mg/kg); 7) naloxone (1 mg/kg) blocking of morphine and burst-firing magnetic field analgesia.

影響評価項目

ばく露

ばく露 パラメータ
ばく露1:
  • unspecified
Modulation type: pulsed
ばく露時間: once every 4 s for 30 min
ばく露2:
  • unspecified
Modulation type: pulsed
ばく露時間: intermittent, once every 4 sec for 30 min
ばく露3:
  • unspecified
Modulation type: pulsed
ばく露時間: intermittent, once every 4 sec for 30 min
ばく露4:
  • unspecified
Modulation type: FM, pulsed
ばく露時間: intermittent, once every 4 sec for 30 min (burst firing pattern) or continuous for 30 min (FM wave)
-
ばく露5:
  • unspecified
Modulation type: FM, pulsed
ばく露時間: for 30 min; continuous in the case of frequency modulated constant wave and intermittent, every 4 s in the case of burst firing pattern and the intermittent FM
-
ばく露6:
  • unspecified
Modulation type: FM, pulsed, CW
ばく露時間: once every 4 s for 30 min or continuously for 30 min
-
ばく露7:
  • unspecified
Modulation type: pulsed
ばく露時間: once every 4 s for 30 min
-

ばく露1

主たる特性
周波数
  • unspecified
タイプ
  • magnetic field
ばく露時間 once every 4 s for 30 min
Modulation
Modulation type pulsed
Additional information

burst-firing pattern

ばく露装置
ばく露の発生源/構造
ばく露装置の詳細 rats placed inside a 25 cm x 25 cm x 25 cm plastic cage with a metal floor grid between a pair of solenoids
Sham exposure A sham exposure was conducted.
Additional information rats were divided into 6 groups: i) sham exposure ii) 5 min magnetic field + 25 min sham field iii) 25 min sham field + 5 min magnetic field iv) 15 min magnetic field + 15 min sham field v) 15 min sham field + 15 min magnetic field vi) 30 min magnetic field
パラメータ
測定量 種別 Method Mass 備考
磁束密度 1 µT - - - -
参照 - - - - U = 5 V

ばく露2

主たる特性
周波数
  • unspecified
タイプ
  • magnetic field
ばく露時間 intermittent, once every 4 sec for 30 min
Modulation
Modulation type pulsed
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 3 µT - - - -
磁束密度 0.3 µT - - - -
磁束密度 0.03 µT - - - -

ばく露3

主たる特性
周波数
  • unspecified
タイプ
  • magnetic field
ばく露時間 intermittent, once every 4 sec for 30 min
Modulation
Modulation type pulsed
ばく露装置
ばく露の発生源/構造
ばく露装置の詳細 experiment was done i) with the setup of E1 and ii) within a Helmholtz coil
パラメータ
測定量 種別 Method Mass 備考
磁束密度 0.5 µT - - - -
磁束密度 1 µT - - - -
磁束密度 2.5 µT - - - -

ばく露4

主たる特性
周波数
  • unspecified
タイプ
  • magnetic field
ばく露時間 intermittent, once every 4 sec for 30 min (burst firing pattern) or continuous for 30 min (FM wave)
Modulation
Modulation type FM, pulsed
Additional information

burst firing pattern FM modulated constant wave

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

No parameters are specified for this exposure.

ばく露5

主たる特性
周波数
  • unspecified
タイプ
  • magnetic field
ばく露時間 for 30 min; continuous in the case of frequency modulated constant wave and intermittent, every 4 s in the case of burst firing pattern and the intermittent FM
Modulation
Modulation type FM, pulsed
Additional information

i) burst firing pattern ii) FM constant wave iii) FM once every 4 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 this experiment was done with i) a burst firing pattern once every 4 s ii) with a frequency modulated constant wave iii) with a frequency modulated signal once every 4 s
Sham exposure A sham exposure was conducted.
パラメータ

No parameters are specified for this exposure.

ばく露6

主たる特性
周波数
  • unspecified
タイプ
  • magnetic field
ばく露時間 once every 4 s for 30 min or continuously for 30 min
Modulation
Modulation type FM, pulsed, CW
Additional information

i) burst firing pattern ii) FM constant wave

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 before exposure rats got a subcutaneous injection of either morphine sulphate, agmatine or physiological saline; exposure was either to a burst firing pattern or a FM constant wave
Sham exposure A sham exposure was conducted.
パラメータ

No parameters are specified for this exposure.

ばく露7

主たる特性
周波数
  • unspecified
タイプ
  • magnetic field
ばく露時間 once every 4 s for 30 min
Modulation
Modulation type pulsed
Additional information

burst firing pattern

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 rats got additional injections with either saline, morphine or maloxone
Additional information rats were divided into 6 gruops: i) saline injection + saline injection + sham exposure ii) saline injection + saline injection + magnetic field iii) morphine injection + maloxone injection + sham exposure iv)morphine injection + maloxone injection + magnetic field v) saline injection + maloxone injection + sham exposure vi) saline injection + maloxone injection + magnetic field
パラメータ

No parameters are specified for this exposure.

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)

In several experiments, robust analgesia (equivalent to about 4 mg/kg of morphine) in rats to thermal stimuli following exposures to weak complex magnetic fields was explored. The analgesia occurred when patterns of magnetic fields with burst-firing-like configurations were presented once every approximately 4 s (for 30 min). The effects were intensity dependent. A different frequency modulated pattern produced analgesic effects more quickly. Analgesia following exposure to the burst-firing magnetic fields were augmented conspicuously by preinjections of morphine or agmatine, but blocked by naloxone.
The data of these experiments indicate that rational design of the temporal structure of weak magnetic fields may be a novel, inexpensive, and reliable technique for elevating thresholds to some classes of painful stimuli.

研究の種別:

研究助成

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