应用闪光视网膜电图(fERG)、细胞色素c氧化酶(CO)组织化学染色及突触囊泡素免疫荧光染色方法检测视神经切断术后,视网膜外网层相关神经元的功能活动及突触可塑性变化。结果显示:fERG b波峰潜伏期在视神经损伤后均显著延长;b波振幅在损伤第3、5d组增高,此后逐渐下降并在7、14、21d组低于正常。外网层CO活性在视神经切断第3、5d上调,此后逐渐下降,至第14、21d低于正常。外网层突触囊泡素阳性颗粒在视神经切断第5d增多,此后逐渐下降,至第14、21d低于正常。本研究结果提示视神经切断后,视网膜内外网层神经元的功能在早期将出现一过性的增强,结构也有相应的代偿性改变,随后即发生跨神经元的逆行性溃变。
In the present study, flash electroretinogram (fERG), cytochrome c oxidase (CO) histochemistry and synaptophysin immuno- fluorescence were used to detect the changes of the synaptic plasticity in the outer plexiform layer (OPL) of rat retina following optic nerve axotomy. The fERG showed that the latency of wave b in each postaxotomy group was significantly longer than that in the control group. However, the amplitudes of wave b were significantly increased in 3 d and 5 d groups and then decreased gradually and lower than normal in 7 d, 14 d and 21 d groups. Similarly, CO activity in the OPL was up-regulated early time (3 d and 5 d ) postaxotomy, then down-regulated gradually (14 d and 21 d ). And the synaptophysin positive granule in the OPL showed a similar changing course: increased early ( day 5 ) and then decreased gradually ( day 14 and day 21 ) after surgery. The present data suggest that after the transection of optic nerve, transneuronal retrograde degeneration occurs in the rat retina OPL following a transient period with compensatory hyperfunction and corresponding structural alterations.