Moga D E, Calhoun M E, Chowdhury A, Worley P, Morrison J H, Shapiro M L
Kastor Neurobiolgoy of Aging Labs, New York, NY, USA.
Neuroscience. 2004;125(1):7-11. doi: 10.1016/j.neuroscience.2004.02.004.
Activity-regulated, cytoskeletal-associated protein (Arc) is an immediate early gene induced in excitatory circuits following behavioral episodes. Arc mRNA is targeted to activated regions of the dendrite after long-term potentiation (LTP) of the dentate gyrus, a process dependent on NMDA receptor activation. We used post-embedding immunogold electron microscopy (EM) to test whether synaptic Arc expression patterns are selectively modified by plasticity. Consistent with previous light microscopic observations, Arc protein was rapidly induced in the dentate gyrus following LTP-producing stimulation of the perforant path and was detectable in granule cell nuclei, somata and dendrites after two hours of high frequency stimulation. Post-embedding EM revealed Arc immunogold labeling in three times as many spines in the middle molecular layer of the stimulated dentate gyrus than in either the ipsilateral outer molecular layer or the contralateral middle and outer molecular layers. This upregulation did not occur with low frequency stimulation of the perforant path. Therefore Arc protein localization may be a powerful tool to isolate recently activated dendritic spines.
活动调节的细胞骨架相关蛋白（Arc）是行为发作后在兴奋性回路中诱导产生的即刻早期基因。在齿状回的长时程增强（LTP）后，Arc mRNA靶向树突的激活区域，这一过程依赖于NMDA受体的激活。我们使用包埋后免疫金电子显微镜（EM）来测试可塑性是否会选择性地改变突触Arc的表达模式。与先前的光学显微镜观察结果一致，在对穿通路径进行产生LTP的刺激后，齿状回中Arc蛋白迅速被诱导产生，在高频刺激两小时后，在颗粒细胞核、胞体和树突中均可检测到。包埋后EM显示，受刺激的齿状回中间分子层中棘突上的Arc免疫金标记数量是同侧外分子层或对侧中间和外分子层中棘突的三倍。对穿通路径进行低频刺激时不会出现这种上调现象。因此，Arc蛋白定位可能是分离最近激活的树突棘的有力工具。
