John T M, Liu G Y, Brown G M
Clarke Institute of Psychiatry, Toronto, Ontario, Canada.
Bioelectromagnetics. 1998;19(3):172-80.
Four separate experiments were carried out to investigate the effect of extremely low frequency magnetic field (MF) exposure (60 Hz, 1 mT rms) on urinary 6-sulphatoxymelatonin (aMT6s) levels in Sprague-Dawley rats. In the first experiment, immature male rats maintained under a regular 12 h daily photoperiod (white fluorescent light) were exposed to a 20 h daily MF exposure for 6 weeks. The second experiment was similar to the first, except that the MF exposure was limited to 10 days. In the third experiment, adult male rats acclimated to a combination of continuous dim red light and regular 12 h daily photoperiod (white fluorescent) were subjected to a single 1 h exposure to intermittent MF (1 min on and 1 min off cycles), 2 h before fluorescent lights went off. The fourth experiment was similar to the third, except that the animals received 2 consecutive days of 20 h daily exposure to intermittent MF, beginning 1 h before the fluorescent lights went off each day. In all four experiments, the circadian profile of urinary aMT6s was examined before, during, and after the MF exposure. No significant effect of 1 mT MF on indoleamine metabolism was observed in any of the above experiments. However, in one of the experiments (no. 4), both the control and the MF groups showed a lower aMT6s level during the exposure days, when compared with that of pre- and post-exposure days, suggesting that the existence of possible effects with lower field strengths at the range of stray field cannot be ruled out.
进行了四项独立实验，以研究极低频磁场（MF）暴露（60Hz，均方根值1mT）对斯普拉格-道利大鼠尿中6-硫酸氧褪黑素（aMT6s）水平的影响。在第一个实验中，将饲养在常规每日12小时光照周期（白色荧光灯）下的未成熟雄性大鼠，每天暴露于MF 20小时，持续6周。第二个实验与第一个实验相似，只是MF暴露时间限制为10天。在第三个实验中，使成年雄性大鼠适应连续昏暗红光和常规每日12小时光照周期（白色荧光）的组合，在荧光灯熄灭前2小时，使其单次暴露于间歇性MF（1分钟开和1分钟关循环）1小时。第四个实验与第三个实验相似，只是动物从每天荧光灯熄灭前1小时开始，连续2天每天暴露于间歇性MF 20小时。在所有四项实验中，在MF暴露前、暴露期间和暴露后，均检测了尿中aMT6s的昼夜变化情况。在上述任何实验中，均未观察到1mT MF对吲哚胺代谢有显著影响。然而，在其中一个实验（实验4）中，与暴露前和暴露后相比，对照组和MF组在暴露期间的aMT6s水平均较低，这表明在杂散场范围内较低场强可能存在影响，这一点不能排除。
