Choi Yoon Mee, Jeong Ji Hoon, Kim Jeong Soo, Lee Byung-Cheon, Je Hyun Dong, Sohn Uy Dong
Department of Pharmacology, College of Pharmacy, Chung Ang University, Seoul, Korea.
Bioelectromagnetics. 2003 Apr;24(3):206-10. doi: 10.1002/bem.10094.
The aim of this study was to determine whether exposure to extremely low frequency magnetic field (ELF-MF) affects the normal diurnal rhythm of the pain threshold in mice. Pain thresholds were evaluated in mice using the hot plate test. A significant increase of pain threshold during night was observed compared to that during day. This rhythm was attenuated by both constant exposure to light (LL) and constant exposure to darkness (DD) for 5 days. Under DD exposure, the diurnal rhythm in pain threshold was restored when mice were exposed to ELF-MF (60 Hz, 1.5 mT for 12 h daily, from 08:00 to 20:00 h) for 5 days. The diurnal rhythm was not reversed under dark with reversed ELF-MF cycle (exposure to 1.5 mT from 20:00 to 08:00 h, next day) for 5 days, although pain threshold in the ELF-MF exposed period of night was slightly decreased. The diurnal rhythm of melatonin analgesic effect related to pain threshold was also observed under DD by the exposure of ELF-MF for 5 days, but not for 5 nights. The present results suggest that ELF-MF may participate in the diurnal rhythm of pain threshold by acting on the system that is associated with environmental light-dark cycle.
本研究的目的是确定暴露于极低频磁场（ELF-MF）是否会影响小鼠疼痛阈值的正常昼夜节律。使用热板试验评估小鼠的疼痛阈值。与白天相比，夜间观察到疼痛阈值显著增加。持续5天暴露于光照（LL）和持续5天暴露于黑暗（DD）均会减弱这种节律。在DD暴露条件下，当小鼠每天从08:00至20:00暴露于ELF-MF（60 Hz，1.5 mT，持续12小时）5天时，疼痛阈值的昼夜节律得以恢复。在黑暗条件下，当ELF-MF周期颠倒（从20:00至次日08:00暴露于1.5 mT）持续5天时，昼夜节律并未逆转，尽管在夜间ELF-MF暴露期间疼痛阈值略有降低。在DD条件下，通过暴露于ELF-MF 5天而非5个夜晚，也观察到了与疼痛阈值相关的褪黑素镇痛作用的昼夜节律。目前的结果表明，ELF-MF可能通过作用于与环境明暗周期相关的系统来参与疼痛阈值的昼夜节律。
