Structural homo- and heterosynaptic plasticity in mature and adult newborn rat hippocampal granule cells
Structural homo- and heterosynaptic plasticity in mature and adult newborn rat hippocampal granule cells
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DOI：
10.1073/pnas.1801889115
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发表时间：
2018-05-15
影响因子：
11.1
通讯作者：
Schwarzacher, Stephan W.
中科院分区：
文献类型：
--
作者：
Jungenitza, Tassilo;Beining, Marcel;Schwarzacher, Stephan W.
成年新生海马颗粒细胞（abGC）有助于空间学习和记忆。abGC被认为在模式分离中起特定作用，不同于发育中出生的成熟GC（mGC）。在这里，我们研究了abGC在哪个确切的细胞年龄突触整合到成人网络中，以及abGC和mGC中表达哪些形式的突触可塑性。我们使用病毒介导的abGC和mGC标记来分析脊柱形态学的变化，作为大鼠体内可塑性的指标。高频刺激内侧穿支通路引起中分子层（MML）的长时程增强和未受刺激的外分子层（OML）的长时程抑制。这种刺激方案引起NMDA受体依赖的同源突触棘扩大的MML和异突触棘收缩的内分子层和OML。这两个过程同时存在于abGC和mGC的个体树突树上。脊髓萎缩抵消了脊髓扩大，因此可以发挥稳态作用，使突触重量正常化。结构同源突触的脊柱可塑性有一个明确的开始，出现在abGCs注射后28天（dpi），其次是异突触脊柱可塑性在35 dpi，并在77 dpi同样存在于成熟abGCs中的mGCs。从35 dpi开始，约60%的abGC和mGC在单细胞水平上显示出显著的同源和异源突触可塑性。abGC和mGC中的结构同源和异源突触可塑性的这种证明定义了abGC的突触可塑性和整合的出现的时间过程。
Adult newborn hippocampal granule cells (abGCs) contribute to spatial learning and memory. abGCs are thought to play a specific role in pattern separation, distinct from developmentally born mature GCs (mGCs). Here we examine at which exact cell age abGCs are synaptically integrated into the adult network and which forms of synaptic plasticity are expressed in abGCs and mGCs. We used virus-mediated labeling of abGCs and mGCs to analyze changes in spine morphology as an indicator of plasticity in rats in vivo. High-frequency stimulation of the medial perforant path induced long-term potentiation in the middle molecular layer (MML) and long-term depression in the nonstimulated outer molecular layer (OML). This stimulation protocol elicited NMDA receptor-dependent homo-synaptic spine enlargement in the MML and heterosynaptic spine shrinkage in the inner molecular layer and OML. Both processes were concurrently present on individual dendritic trees of abGCs and mGCs. Spine shrinkage counteracted spine enlargement and thus could play a homeostatic role, normalizing synaptic weights. Structural homosynaptic spine plasticity had a clear onset, appearing in abGCs by 28 d postinjection (dpi), followed by heterosynaptic spine plasticity at 35 dpi, and at 77 dpi was equally as present in mature abGCs as in mGCs. From 35 dpi on, about 60% of abGCs and mGCs showed significant homo- and heterosynaptic plasticity on the single-cell level. This demonstration of structural homo- and heterosynaptic plasticity in abGCs and mGCs defines the time course of the appearance of synaptic plasticity and integration for abGCs.