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 irradiation of very low frequency electromagnetic fields on learning and memory in rats. Methods Helmholtz coils were used to generate uniformly weak electromagnetic fields (0.1,1.2,1.6mT) with continuous adjustable 50Hz intensity. The rats were exposed to young rats (2-3 months) and old rats (18 months) for 10 days to 8 months Morris water maze test was used to detect the escape latency and the wear coefficient of the rats after electromagnetic field irradiation to reflect the changes of navigation and spatial exploration behavior. Results In young age rats, the escape latency of 0.1, 1.2 and 1.6 mT groups was shortened and the coefficient of wearshort was increased, while there was significant difference between 1.2 and 1.6 mT groups and the control group There was no significant difference between the ring coefficient and the control group. In the 1.2mT group, the latency was prolonged 90 days after the continuous irradiation and the reduction of the perforated ring coefficient was significantly different from that of the control group. In the 0.1mT group, the latency of the rats in the 0.1mT group did not change significantly. After 4 months of irradiation, the latency of the rats was prolonged. After 8 months of irradiation, the latency prolonged significantly. Conclusion 50Hz weak electromagnetic field can shorten the learning and memory of young rats exposed to short-term electromagnetic fields, but long-term exposure can inhibit learning and memory. Long-term weak irradiation can inhibit learning and memory in older rats.