极低频电磁场暴露对大鼠脑电图及脑组织结构的影响

Effects of extremely low frequency electromagnetic field exposure on the electroencephalogram and morphological structure of the rat brain

目的探讨极低频电磁场对大鼠脑电图及脑组织结构的影响。方法选用二级雄性Wistar大鼠48只,随机分为对照组和磁场暴露组,每组24只,磁场暴露组大鼠置于ELF-EMFS(50 Hz,400μT,<1V/M)中连续暴露60 d。终止暴露后6 h、7 d、15 d和30 d,采用MP150生理监测仪监测脑电图近似熵和功率谱分布;采用光镜观察大脑皮层组织结构。结果 (1)磁场组大鼠脑电图(EEG)于暴露后6 h和7 d,近似熵降低;(2)磁场组大鼠EEG信号于6 h出现δ频段相对功率值呈升高改变,而β频段相对功率值降低;对照组和入场前磁场组大鼠EEG基本节律为30μV左右的β波及少量不典型α波,偶见低幅θ波和δ波,磁场组大鼠θ波和δ波增多以及波幅增加,以β波为主要节律。(3)磁场组大鼠大脑皮层神经元呈缺血性改变。结论极低频电磁场暴露会导致大鼠EEG近似熵降低、功率谱分布异常及脑组织结构损伤,且此改变主要发生于终止暴露后早期。

Objective To explore the effects of extremely low frequency electromagnetic fields （ELF-EMFS）on rat brain structural morphology and electroencephalogram （EEG）. Methods Forty-eight heatthy 3- week old male Wistar rats were randomly divided into control group and electromagnetic field exposure group （n = 24 per group）. The rats in the ELF-EMFS group （50 continuously exposed for 60 days. A MP150 physiologi entropy and spectral power distribution of EEG at 6 h Hz, 400 μT and 〈1 V/M） were al monitor was used todetect the approximate 7 d, 15 d and 30 d after exposure. Light microscopy was applied to observe the Structural morphology of cerebral cortex. The number of neurons was analyzed by image analysis. Results Firstly, rats in the ELF-EMFS group showed de- creased approximate entropy at 6 h and 7 d after exposure. Secondly, the relative power spectrum ofδ wave was increased significantly in the ELE-EMFS group at 6 h after exposure, while the relative power spectrum of β wave was decreased. The basic rhythm of EEG in the rats of control group and pre-exposure group appeared β wave and atypical α wave at 30 μV, while low amplitude of δ and θ waves were rarely observed. The number and amplitude of θ and δ waves increased significantly in the ELE-EMFS group, especially the β wave. Thirdly, neurons of cerebral cortex showed ischaemic changes in the ELE-EMFS group. Conclusions ELF-EMFS exposure can lead to the decrease of approximate entropy, abnormal distribution of power spectrum and injures of brain structure at early period after the termination of ELF-EMFS exposure .