基于氢质子磁共振波谱技术研究L波段微波辐射对大鼠学习和记忆的影响

目的:基于氢质子磁共振波谱（1H-MRS）技术，分析L波段微波辐射对大鼠学习和记忆功能的影响。方法:SPF级雄性Wistar大鼠26只，随机分为假辐射组（Sham组）、L波段30 mW/cm2微波辐射组（L30组）。将L30组大鼠放置于有机玻璃照射盒中，使用L波段微波辐射源从背侧照射10 min；Sham组大鼠除未行微波辐射外其他处理与照射组相同。采用Morris水迷宫方法于辐射后1 d和7 d对各组大鼠的学习和记忆功能进行检测。使用1H-MRS于辐射后1 d和7 d检测鼠脑中的N-乙酰天门冬氨酸（N-acetylaspartate, NAA）、胆碱（Choline, Cho）、肌酸（Creatine, Cr）水平。结果:微波辐射后1 d和7 d，与Sham组相比，L30组平均逃避潜伏期有延长趋势，但无统计学意义（P>0.05）。1H-MRS检测结果显示辐射后1 d，与Sham组比较，L30组1H-MRS波谱NAA/Cr值显著降低（P<0.05），Cho/Cr值无显著差异（P>0.05）；辐射后7 d，与Sham组比较，L30组大鼠脑部NAA/Cr和Cho/Cr值均无显著差异（P>0.05）。结论:30 mW/cm2 L波段微波辐射后1 d大鼠脑内NAA/Cr显著降低，而学习和记忆行为学指标无显著改变，提示利用1H-MRS技术能够在被试未出现显著行为学改变时检测出微波辐射对学习和记忆相关神经元的影响。

1H-proton magnetic resonance spectroscopy for studying effects of L-band microwave radiation on learning and memory functions of rats

Abstract: Objective To investigate the effects of L-band microwave radiation on the learning and memory functions of rats based on 1H-proton magnetic resonance spectroscopy (1H-MRS). Methods Twenty-six SPF male Wistar rats were randomly divided into Sham group and 30 mW/cm2 L-band microwave radiation group (L30 group). The rats in L30 group were restrained in plastic cages and exposure to 30 mW/cm2 L-band microwave radiation for 10 min. The incident direction of the microwave was from dorsal to ventral. The rats in Sham group were also restrained in the same cages for 10 min, without any microwave radiation. Both learning and memory functions of rats were evaluated at 1 d and 7 d after the radiation using Morris water maze. The level of N-acetylaspartate (NAA), choline (Cho) and creatine (Cr) in the rats’ brain were measured with 1H-MRS. Results Compared with that of Sham group, the average escaping latency of L30 group at 1 d and 7 d after microwave radiation was prolonged, but there was no statistical significance between two groups (P>0.05). The results of 1H-MRS examination demonstrated that at 1 d after the radiation, the NAA/Cr of L30 group was significantly lower than that of Sham group (P<0.05), while the Cho/Cr was similar in two groups, without significant differences (P>0.05); and that at 7 d after the radiation, there was no significant difference in both of NAA/Cr and Cho/Cr between L30 group and Sham group (P>0.05). Conclusion 30 mW/cm2 L-band microwave radiation can lead to a significant decrease of intracerebral NAA/Cr in rat at 1 d after microwave exposure, without resulting in obvious changes in the behavioral indexes of learning and memory, which suggests that 1H-MRS can be used for evaluating the microwave radiation induced damage to neurons related to learning and memory before any significant changes of behavioral measurements can be observed.