AMPA受体及其GluR2亚基在大鼠初级视皮层可塑性中的作用研究

Theeffect of AMPA receptor and its GluR2 subunit in the plasticity of primary visual cortex in rats

目的观察闪光刺激对大鼠初级视皮层诱发电位的影响,探讨AMPA受体及其GluR2亚基在大鼠初级视皮层可塑性中的作用。方法 24只成年SD大鼠随机分为3组:A组(空白对照组:不接受闪光刺激)、B组(光刺激组:接受紫光闪光刺激)、C组(阻断剂组:接受紫光闪光刺激并注射AMPA受体阻断剂)。各组大鼠麻醉、固定后分别在初级视皮层(V1区)植入记录电极,在额叶植入参考电极,在V1区(与记录电极同侧)植入微细玻璃微电极做微量注射,B组和C组手术恢复后连续5 d每天于固定时间行紫光闪光刺激1 h,之后行微量注射生理盐水和AMPA受体阻断剂后,在相同闪光刺激条件下,给予一串高频刺激,记录高频刺激前后初级视皮层(V1区)的视觉诱发电位,分析两组视觉诱发电位的幅值和潜伏期的变化;western blot检测各组大鼠强直性闪光刺激前后初级视皮层GluR2蛋白含量的变化。结果 B组和C组在接受强直性闪光刺激后诱发电位幅值较之前明显升高,且潜伏期变短(均P<0.01),在强直性闪光刺激后,C组幅值显著高于B组、潜伏期显著短于B组(均P<0.01);在强直性闪光刺激之前,B组和C组的幅值和潜伏期均差异无显著性。western blot结果显示,B组大鼠GluR2含量在强直性闪光刺激前显著高于强直性闪光刺激后,但显著低于A组(均P<0.05),C组GluR2含量与B组在强直性闪光刺激前后均差异无显著性。结论强直性闪光刺激能使大鼠初级视皮层视觉诱发电位呈现LTP样反应,AMPA及其GluR2亚基参与了闪光刺激致大鼠初级视皮层的可塑性变化。

[Objective ] To observe the influence of flash stimulation on the evoked potential in primary visual cortex and investigate the effect of AMPA receptor and its subunit GluR2 in the plasticity of the primary visual cor- tex in rats. [ Methods ] Twenty-four adult Sprague-Dawley rats were divided into 3 groups： Group A（Control group）, Group B（flashing stimulation group） Group C （flashing stimulation and injection AMPA receptor blocker）. All the rats were anesthetized, fixed, implanted recording electrodes in the primary visual cortex （V1）, reference electrode in the frontal lobe and fine glass mieroelectrodes in the primary visual cortex （the same side of recording electrode） were givenmicroinjection. Group B and Group C rats were given violet flash stimulation after operation recovery for 1 hour at fixed time for 5 days. Then injection of AMPA receptor blocker, with the same flashing conditions, a string of high-frequency flashing stimulation was applied to the primary visual cortex. The flash visual evoked potentials （FVEP） were recorded before and after high-frequency stimulation in the primary visual cortex（V1）, changes of am- plitude and latency were analyzed in each group. Western blot was used to check the changing of CluR2 in the threegroup before and after the high- frequency stimulation in the primary visual cortex. [ Results ] After high-frequency stimulation, the amplitude of the FVEP was significant increased （P 〈0.01） and the latency was significant shorter （P 〈0.01） both in group B and C. Meanwhile, compared with the group B, the amplitude of the FVEP was significant in- creased （P 〈0.01） and the latency was significant shorter （P 〈0.01）, but there were no significant difference both in the amplitude and the latency before high-frequency stimulation. The western blot results demonstrated that in the group B, before the high-frequency stimulation the expression of GluR2 in the primary visual cortex was significant higher than after stimulation, but was significant decreased than the control group. In the group C, the expression of GluR2 was no significant difference compared with the group B before and after high-frequency stimulation. [ Con- clusion ] High-frequency stimulation could make the visual evoked potential present LTP-like reaction. AMPA re- ceptors and GluR2 subunit was involved in the plasticity induced by the flash stimulation in primary visual cortex.