激光照射对小鼠非空间记忆能力影响的实验研究

目的分析不同照射剂量、不同波长和不同照射方式的激光体外照射小鼠头部海马区对小鼠非空间记忆能力的影响。方法采用专门设计的激光照射装置,照射光源为Nd∶YAG脉冲激光器和半导体激光器。脉冲激光输出波长为1 064、532 nm;半导体激光器连续输出,激光波长为659、532 nm,最大输出激光能量为180 mJ,光束直径5 mm。昆明小鼠80只,分为11组,分别进行小鼠头部海马区激光照射和非空间迷宫实验,并将激光照射前后小鼠出迷宫的时间进行比对。结果 （1）脉冲激光组：激光波长为532 nm和1 064 nm,大脑皮质区激光辐射功率密度分别为2.79×1010 W/m2和6.90×1010 W/m2时,小鼠出迷宫时间与照前相比无明显差异;而脑皮质区激光辐射功率密度分别为8.50×1010～4.60×1011 W/m2和2.40×1011～1.61×1012 W/m2时,小鼠出迷宫时间明显延长,差异显著。（2）连续激光组：激光波长为532nm和659nm,脑皮质区激光辐射能量密度分别为8.90×103～2.64×104 J/m2和1.75×104～5.30×104 J/m2,每天照射时间15min,连续照射3 d,第2天与第1天相比,出迷宫时间没有统计学意义;第3天与第1天相比,小鼠出迷宫时间明显延长,差异显著。结论脉冲激光和连续激光照射均可使小鼠的记忆能力降低;激光产生的生物学作用与照射剂量、激光波长和激光的发射方式有关,激光照射存在一定的累积效应。

Effect of Laser Irradiation on Non-Spatial Memory of Mice

Objective To investigate and analyze the effect of laser irradiation on the non-spatial memory of mice,the hippocampus of mice is exposed by means of the different radiation exposure,wavelength and emission mode of laser irradiation in vitro and followed on test in the non-spatial maze. Methods Laser exposure device used in the experiment of laser irradiation on mice,including Nd ∶YAG pulsed laser and semiconductor laser,measuring instruments and software of computer detection and control has been specially designed and built up.Laser wavelengths of the pulse laser in the system were 1 064 nm and 532 nm,and wavelength of semiconductor continuous wave（cw） laser were 659 nm and 532 nm.The beam diameter was 5 mm.The maximum output of laser was 180 mJ.Eighty of Kunming（KM） mice were divided into 11 groups to perform the experiments of laser irradiation on the mice hippocampus as well as the test of non-spatial maze.The time that mice got out of the maze pre-and post-irradiation was compared. Results（1） The pulsed laser groups： for laser wavelength of 532 nm and 1 064 nm,the time that mice got out of the maze was not significantly different by contrast of the pre-irradiation when the irradiance of cerebral cortex was respectively 2.79×1010 W/m2 and 6.90×1010 W/m2,but the time was distinctly prolonged when the irradiance of cerebral cortex was respectively 8.50×1010-4.60×1011 W/m2 and 2.40×1011-1.61×1012 W/m2.（2） The continuous laser groups： for laser wavelength of 532 nm and 659 nm,the time that mice got out of the maze was significantly prolonged when the radiation exposure of cerebral cortex was respectively 8.90×103-2.64×104 J/m2 and 1.75×104-5.30×104 J/m2 and that the exposure time was 15 min/d.In the continuous irradiation for three days,the time of the mice got out of the maze had no statistical significance when the second day compared with the first day,but the time was significantly prolonged when the third day compared with the first day. Conclusions Both the pulsed laser and CW laser can reduce the memory ability of the mice.The biological effect of laser is relative to the radiation exposure,wavelength and emission mode of laser,and that laser irradiation exists certain cumulative effect in biology.