Developmental presence and disappearance of postsynaptically silent synapses on dendritic spines of rat layer 2/3 pyramidal neurons
Developmental presence and disappearance of postsynaptically silent synapses on dendritic spines of rat layer 2/3 pyramidal neurons
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DOI：
10.1113/jphysiol.2007.149336
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发表时间：
2008-03-15
影响因子：
5.5
通讯作者：
Sabatini, Bernardo L.
中科院分区：
文献类型：
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作者：
Busetto, Giuseppe;Higley, Michael J.;Sabatini, Bernardo L.
沉默突触是其激活引起NMDA型谷氨酸受体（NMDAR）而不是AMPA型谷氨酸受体（AMPAR）介导的电流的突触。沉默突触在出生后发育的早期是突出的，并且被认为在神经元回路的活动和感觉依赖性细化中发挥作用。解释其沉默性质的机制一直存在争议，并提出了突触前和突触后机制。在这里，我们使用双光子激光uncaging的谷氨酸直接激活谷氨酸受体和测量AMPAR和NMDAR依赖性电流对个别树突棘的大鼠体感皮质层2/3锥体神经元。我们发现，树突棘缺乏功能表面AMPAR通常发现出生后12天（P12）之前，但在老年动物缺席。此外，缺乏AMPAR的棘与有释放能力的突触前末梢接触。在P12之后，单个棘的AMPAR/NMDAR电流比继续增加，这与AMPAR继续增加到突触后末梢一致。我们的研究结果证实了突触后沉默突触的存在，并表明，脊柱的形态是不是强有力的预测其AMPAR含量。
Silent synapses are synapses whose activation evokes NMDA-type glutamate receptor (NMDAR) but not AMPA-type glutamate receptor (AMPAR) mediated currents. Silent synapses are prominent early in postnatal development and are thought to play a role in the activity- and sensory-dependent refinement of neuronal circuits. The mechanisms that account for their silent nature have been controversial, and both presynaptic and postsynaptic mechanisms have been proposed. Here, we use two-photon laser uncaging of glutamate to directly activate glutamate receptors and measure AMPAR- and NMDAR-dependent currents on individual dendritic spines of rat somatosensory cortical layer 2/3 pyramidal neurons. We find that dendritic spines lacking functional surface AMPARs are commonly found before postnatal day 12 (P12) but are absent in older animals. Furthermore, AMPAR-lacking spines are contacted by release-competent presynaptic terminals. After P12, the AMPAR/NMDAR current ratio at individual spines continues to increase, consistent with continued addition of AMPARs to postsynaptic terminals. Our results confirm the existence of postsynaptically silent synapses and demonstrate that the morphology of the spine is not strongly predictive of its AMPAR content.