He-Ne激光对大鼠离体颈上神经节快兴奋性突触后电位的影响

Effect of He-Ne laser on fast excitatory postsynaptic potential(f-EPSP) of neurons in the isolated rat superior cervical ganglia

本文应用细胞内生物电记录技术,观测不同功率、不同照射时间的He—Ne激光(脉冲频率为1 Hz、波长为632.8nm)对大鼠离体颈上神经节后神经元的膜电导和快兴奋性突触后电位(f-EPSP)的影响,以研究He—Ne激光对突触传递过程的作用机制。实验结果:(1)节后神经元快兴奋性突触传递过程对照射的He—Ne激光功率密度和照射时间的长短有选择性;(2)功率密度为2 mW/cm2的He—Ne激光对膜电导和f-EPSP的影响呈两个阶段:在照射初期(头2分钟内)引起膜电导增大(P<0.05),同时f-EPSP幅值增大(P<0.05),甚至能产生动作电位;在激光照射后期(后3至10分钟)引起膜电导减少,f—EPSP幅值下降至低于照射前,并持续稳定较长一段时间;(3)功率密度为5 mW/cm2的He—Ne激光照射期f-EPSP幅值持续下降,不出现两阶段;(4)功率密度为2 mW/cm2的He—Ne激光的照射可降低快兴奋性突触后电位产生阈值,增加其发放频率。实验结论:(1)功率密度为2 mW/cm2,脉冲频率1 Hz的He—Ne激光短时间照射可提高突触后膜上Na+、K+离子通透性,使膜电导增大而导致神经细胞突触过程的快兴奋性突触后电位幅值增加;(2)在功率密度为2mW/em2的He—Ne激光调节交感神经节快兴奋传递的过程中存在两时相效应,即激光照射初期的短时间增强效应和激光照射后期的长时间减弱效应。

The effects of He-Ne laser with wavelength 632.8 nm on fast excitatory postsynaptic potential(f-EPSP) of neurons in isolated rat superior cervical ganglia were investigated by means of intracellular recording techniques. The neurons with stable f-EPSP were irradiated by power densities of 1 mW/cm2-5 mW/cnr, pulse frequency of 1 Hz laser. The results were as follows:(1) the effect is different with various power density and time; irradiated by the 2mW/cm2 laser, the membrane conductance and the amplitude of the f-EPSP could augment (P<0.05) and even caused action potential(AP) at the end of the first two minute; the membrane conductance and the f-EPSP could descend and lasted for 3 to 10 minutes later; but the 5 mW/cnr laser irradiation could depress the f-EPSP for the irradiating times. (2)with 2mW/cnr power density, He-Ne laser clearly promote the integration of neurons. The results indicated that there were the second-order phases in the interaction of He-Ne laser with neurons; first, the initial short-time promotive effect; second, the late long-time effect of inhibition. The mechanism of the effect He-Ne laser on f-EPSP of postganglionic neurons may be the photobiology effects of low power laser.