极低频弱电磁场对大鼠学习记忆的影响

Effects of Exposure to Extremely Low Frequency Electromagnetic Field on Morris Learning and Memory Among Rats

目的研究极低频弱电磁场短期及长期照射对大鼠学习记忆的影响。方法用Helmholtz线圈产生50Hz,强度连续可调的均匀弱电磁场(0.1、1.2、1.6mT),分别对青龄(2～3月)及大龄(18个月)SD大鼠照射10d～8个月,通过Morris水迷宫实验检测电磁场照射后大鼠逃避潜伏期和穿环系数以反应定位航行和空间探索行为功能的变化。结果青龄大鼠照射10d,0.1、1.2、1.6mT组的逃避潜伏期缩短,穿环系数增大,1.2、1.6mT组与对照组差异有显著性;1.6mT组停止照射30d后逃避潜伏期和穿环系数与对照组差异无显著性;1.2mT组连续照射90d,潜伏期延长,穿环系数减少熏与对照组差异有显著性。大龄大鼠0.1mT组照射10d,潜伏期变化不显著;照射4个月后潜伏期延长,照射8个月后潜伏期延长更显著。结论50Hz弱电磁场对青龄大鼠短期电磁场照射可以暂时促进学习记忆,但长期照射则抑制学习记忆;对大龄大鼠长期弱照射明显抑制学习记忆能力。

Objective To study the effects of short-term and long-term exposure to extremely low frequency electromagnetic field(ELFEMF)on Morris learning and memory among rats. Methods Both younger(2-3 months old)and adult(18 months old)male SD rats were exposed to 50 Hz uniform ELFEMF with continuously adjusted intensities(0.1,1.2,1.6 mT) developed by Helmholtz coil pair for 10 days to 8 months. The levels of escape latency and the crossing annulus coefficients reflecting the behavioral changes in place navigation ability and spatial probe ability were examined by Morris water maze after exposure to ELFEMF among rats. Results The escape latency was shortened and the crossing annulus coefficients were increased compared with those of control group when the younger rats were exposed to 0.1,1.2 and 1.6 mT ELFEMF for 10 days respectively,and only revealed significant differences in 1.2 and 1.6 mT ELFEMF exposure groups compared with those of control group. In the younger rats of 1.6 mT ELFEMF exposure group with 10-day exposure ,their escape latencies were prolonged and the crossing annulus coefficients were decreased gradually and showed no significant differences compared with those of control group after the 30-day blank exposure period without ELFEMF.The younger rats of 1.2 mT ELFEMF exposure group showed significantly longer escape latency and lower crossing annulus coefficient compared those of control group after continuous 90-day exposure to 1.2 mT ELFEMF. The escape latency of adult rats in 0.1 mT ELFEMF exposure group showed no significant difference after 10-day exposure,was prolonged after 4-month exposure,and was significantly prolonged further more after 8-month exposure. Conclusion The learning and memory ability could be promoted by short-term ELFEMF exposure and impaired by long-term ELFEMF exposure for the young rats,and could be obviously inhibited by long-term ELFEMF exposure for the adult rats.