Liao D, Zhang X, O'Brien R, Ehlers M D, Huganir R L
Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
Nat Neurosci. 1999 Jan;2(1):37-43. doi: 10.1038/4540.
Many excitatory synapses are thought to be postsynaptically 'silent', possessing functional NMDA but lacking functional AMPA glutamate receptors. The acquisition of AMPA receptors at silent synapses may be important in synaptic plasticity and neuronal development. Here we characterize a possible morphological correlate of silent synapses in cultured hippocampal neurons. Initially, most excitatory synapses contained NMDA receptors, but only a few contained detectable AMPA receptors. Synapses progressively acquired AMPA receptors as the cultures matured. AMPA receptor blockade increased the number, size and fluorescent intensity of AMPA receptor clusters and rapidly induced the appearance of AMPA receptors at 'silent' synapses. In contrast, NMDA receptor blockade increased the size, intensity and number of NMDA receptor clusters and decreased the number of AMPA receptor clusters, resulting in an increase in the proportion of 'silent' synapses. These results suggest that the number of silent synapses is regulated during development and by changes in synaptic activity.
许多兴奋性突触被认为在突触后是“沉默”的，具有功能性N-甲基-D-天冬氨酸（NMDA）受体，但缺乏功能性α-氨基-3-羟基-5-甲基-4-异恶唑丙酸（AMPA）谷氨酸受体。在沉默突触处获得AMPA受体可能在突触可塑性和神经元发育中起重要作用。在这里，我们描述了培养的海马神经元中沉默突触可能的形态学相关物。最初，大多数兴奋性突触含有NMDA受体，但只有少数含有可检测到的AMPA受体。随着培养物的成熟，突触逐渐获得AMPA受体。AMPA受体阻断增加了AMPA受体簇的数量、大小和荧光强度，并迅速诱导“沉默”突触处出现AMPA受体。相反，NMDA受体阻断增加了NMDA受体簇的大小、强度和数量，并减少了AMPA受体簇的数量，导致“沉默”突触的比例增加。这些结果表明，沉默突触的数量在发育过程中以及通过突触活动的变化受到调节。
