この研究は、マウスへの超低周波磁界（ELF MF：50 Hz）ばく露が認知記憶タスクおよび海馬ニューロンの形態学に与える影響を調べた。実験では、ELF MF（1 mT、12時間／日）のばく露日数が7-10日間の場合のみ、新規オブジェクト連想認知の記憶における欠損および海馬での樹状突起棘密度の低下が見られた；それは一過性で、自発的移動の変化との相関は見られなかった；アデノ随伴ウイルス（AAV）ベクターにより海馬にニューリチン遺伝子を過剰発現させると、ニューリチンレベルおよび樹状突起棘密度が有意に増加した；この増加は、ELF MFによる樹状突起棘密度の低下が原因の認知記憶への影響を防止した、と報告している。
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Neuritin was recently discovered as an important growth factor for neural development, which promotes neuronal outgrowth and arborization in the brain. Mice with an overexpression of neuritin in the hippocampus were experimentally created (transfection with a viral vector) and used beside normal mice.
Mice were divided into the following groups: exposure of normal mice to a magnetic field with 1) 0.4 mT or 2) 0.6 mT for 7 days and 3) with 1 mT for up to 21 days. Moreover, 4) neuritin-viral-transfected, 5) sham-viral-transfected and 6) saline-transfected mice were exposed to a magnetic field with 1 mT for 10 days. Additional sham exposed control groups were used for each experiment. (remark EMF-Portal: not all group sizes were mentioned, but stated sizes were at least n=10).
Exposure to the magnetic field had no effect on the locomotor activity of mice, whereas the object recognition was significantly impaired in mice exposed to a 1 mT magnetic field for 7 days (group 3) compared to the control group.The dendritic spine density of neurons in the hippocampus was significantly reduced after exposure to a 1 mT magnetic field for 7 or 10 (group 3) days compared to the control group. However, all effects were transient and could not be detected after 14 days anymore.
Mice with an overexpression of neuritin in the hippocampus (group 4) showed no significant differences between the exposure and control groups in dendritic spine density and object recognition after 10 days. Moreover, both parameters were significantly increased compared to mice with normal neuritin protein expression (groups 5 and 6).
The authors conclude that exposure of mice to a 50 Hz magnetic field could impair the memory of mice and alter the morphology of neurons in the hippocampus. However, neuritin could attenuate these effects.
