この研究は、「EMFと脳の鉄分過剰の同時ばく露の方が、どちらか一つの単独ばく露よりも脳組織および認知プロセスに大きな影響を与えるか否か」との仮説を検証した。24匹のWister 雄ラット（5週齢）を各８匹の3群に分けた：(1) EMF（900 MHz）ばく露群、 (2) 鉄分過剰投与＋EMFばく露群、 (3) EMF疑似ばく露（鉄分投与なし）群。ダイポールアンテナを用いて、EMFばく露用チャンバ内電界強度を一様になるようにし、SARは0.05-0.18W/kgと推定している。1日1時間、21日間連続のばく露（または疑似ばく露）終了後、空間学習タスク（モリス水迷路ナビゲーションタスク、放射状迷路ワーキング記憶タスク、物体探索タスクなど）を行い、モノアミンや代謝産物（ドーパミン、セロトニン）、酸化ストレスを測定した。その結果、EMF群では、物体探索タスクの成績が低かったが、ナビゲーションおよびワーキング記憶タスクには影響がなかった；EMF群では、主に海馬のモノアミン含有量に変化が見られた；鉄分過剰投与＋EMF群では、EMF群に比べ、行動および神経化学物質への影響が大きくなかった；両群とも全体的に酸化ストレスが見られなかった、と報告している。
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To investigate whether co-exposure to electromagnetic fields and iron overload has a greater impact on rat brain tissues than electromagnetic field exposure alone.
Neurodegenerative diseases (e.g. Parkinson's disease or Alzheimer's disease) have been suggested to be linked to electromagnetic fields and iron overload in the brain. Thereby, the combination of both factors could have a greater impact than each treatment for itself.
Three groups of rats were examined (n=8 per group): 1.) electromagnetic field exposure, 2.) electromagnetic field exposure + iron administration (daily injection of 3 mg FeSO4 per kg body weight during 21 consecutive days) and 3.) sham exposure. After the exposure period of 21 days, behavior tests were performed (post-treatment day 1-8: Morris water maze, post-treatment day 14-20: eight-arm radial maze, post treatment day 21, 22 or 23: object exploration task). At the end of the experimental period, rats were killed for biochemical measurements.
|ばく露時間||1 hour per day for 21 consecutive days|
|チャンバの詳細||cage (40 cm x 26 cm x 16 cm) with a plexiglas cover containing 6 rats was placed in the exposure chamber, chamber was formed by absorbent material to limit stray reflections|
|ばく露装置の詳細||apparatus (containing the dipole antenna and the chamber) was placed in a temperature controlled (20°C), dimly lit room (1,7 m x 3.2 m) on a table; antenna was placed at a 50 cm distance to the center of the chamber|
|Sham exposure||A sham exposure was conducted.|
No significant differences regarding learning and memory were observed in the Morris water maze and eight-arm radial maze between the groups. However, exposed rats from group 1 (electromagnetic field) and group 2 (electromagnetic field + iron) showed significantly impaired results in the object exploration test in comparison to the sham exposed rats.
Rats exposed to an electromagnetic field (group 1) showed significant decreases in the levels of dopamine and serotonin in the hippocampus compared to group 2 and group 3 (sham exposure). The level of serotonin and its metabolite (5-hydroxyindolacetic acid) was significantly increased in the cerebellum in both exposure groups (group 1 and 2) in comparison to the sham exposure group. Additionally, the level of dopamine was significantly increased in the striatum of group 2 compared to group 1 and group 3.
No differences regarding oxidative stress parameters were found between the groups.
The authors conclude that electromagnetic field exposure had an impact on the brain of rats, but no synergistic effects of exposure to an electromagnetic field and iron overload occurred.