Rosen Kenneth M, Moghekar Abhay, O'Brien Richard J
Department of Neurology, Caritas St. Elizabeth's Medical Center, Tufts University School of Medicine, Boston, MA 02135, USA.
Mol Cell Neurosci. 2007 Apr;34(4):578-91. doi: 10.1016/j.mcn.2006.12.008. Epub 2006 Dec 29.
In cultured spinal neurons, NMDA receptors are absent from excitatory synapses under basal conditions, but can be made to appear at excitatory synapses following blockade of excitatory synaptic activity. The activity dependent synaptic localization of NMDA receptors is critically dependent on both the gradual, global accumulation of the NR2A and NR2B subunits and on a rapid, surface redistribution phase that is primed by the accumulation of NR2A and NR2B and inhibited by synaptic activity. Global changes in NR2A and NR2B accumulation and heterogeneous increases in synaptic NMDA receptor localization can also result from inhibitors of proteasomal processing, from manipulations of proteasomal subunit composition and from media conditioned by neurons undergoing synaptic scaling. While proteasomal processing is a mechanism shared with AMPA receptor scaling in cultured spinal neurons, diffusible factors, heterogeneity, and a rapid surface redistribution phase appear to be unique to activity dependent synaptic NMDA receptor localization.
在培养的脊髓神经元中，基础条件下兴奋性突触处不存在NMDA受体，但在兴奋性突触活动被阻断后，NMDA受体可出现在兴奋性突触处。NMDA受体的活性依赖性突触定位关键取决于NR2A和NR2B亚基的逐渐整体积累以及快速的表面重新分布阶段，该阶段由NR2A和NR2B的积累引发，并受突触活动抑制。蛋白酶体加工抑制剂、蛋白酶体亚基组成的操作以及经历突触缩放的神经元所 conditioned 的培养基也可导致NR2A和NR2B积累的整体变化以及突触NMDA受体定位的异质性增加。虽然蛋白酶体加工是培养的脊髓神经元中与AMPA受体缩放共有的机制，但可扩散因子、异质性和快速表面重新分布阶段似乎是活性依赖性突触NMDA受体定位所特有的。 （这里“media conditioned by neurons undergoing synaptic scaling”中“conditioned”可能有误，不太明确准确意思，暂按原文翻译）
