Polyribosomes under developing spine synapses: growth specializations of dendrites at sites of synaptogenesis.
Polyribosomes under developing spine synapses: growth specializations of dendrites at sites of synaptogenesis.
复制标题
发育中的脊柱突触下的多核糖体：突触发生位点树突的生长特化。
DOI：
10.1002/jnr.490130106
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发表时间：
1985
影响因子：
4.2
通讯作者：
Falk,PM
中科院分区：
文献类型：
--
作者：
Steward,O;Falk,PM
我们以前曾报道过，有一个显着增加的多聚核糖体与树突棘在突触生长期间引起的去神经病变。我们认为突触后部位的多聚核糖体可能以某种方式参与突触的生长。为了进一步验证这一假说，本研究确定发育期生长的突触是否也有多聚核糖体的积累。我们在7、10、15、20和28日龄时用电子显微镜检查了发育中大鼠的齿状回，这跨越了该结构中突触发生的主要时期。定性观察显示，在最年轻的动物（7和10天的年龄）的棘突触下的多聚核糖体的戏剧性的积累。随着突触的发育，多聚核糖体的积累变得不那么引人注目，因此到28日龄时，齿状回的神经元在质量上已经成熟。为了确定棘突触下的多聚核糖体与突触发育之间的关系，使用定量电子显微镜方法评估每个年龄的齿状回背叶神经元中的突触密度（突触数量/100 μ m2）和含多聚核糖体棘的发生率（棘突触与底层多聚核糖体的比例）。突触密度和棘与多聚核糖体的比例之间呈反比关系。突触密度在7 - 28日龄之间以几乎线性的方式增加，实际上略高于成熟大鼠的水平，而含多聚核糖体的棘的发生率在最年轻的年龄最高，并随着发育而下降。因此，在最大突触生长期间，多聚核糖体在棘突触下最为突出。这些结果，连同我们先前观察到的在损伤诱导的生长过程中棘下的多聚核糖体数量增加，表明多聚核糖体代表突触构建位点处树突的结构特化。我们认为它们产生的蛋白质参与了突触的生长。
We have previously reported that there is a dramatic increase in polyribosomes associated with dendritic spines during periods of synapse growth induced by denervating lesions. We suggested that polyribosomes at the postsynaptic site may somehow be involved in the growth of synapses. To evaluate this hypothesis further, the present study determines whether synapses which are growing in the developmental period also have accumulations of polyribosomes. We examined the dentate gyrus of the developing rat electron microscopically at 7, 10, 15, 20, and 28 days of age, which spans the major period of synaptogenesis in this structure. Qualitative observations revealed dramatic accumulations of polyribosomes under spine synapses in the youngest animals (7 and 10 days of age). With synapse development, the accumulations of polyribosomes became less dramatic, so that by 28 days of age, the neuropil of the dentate gyrus appeared qualitatively mature. To determine the relationship between polyribosomes under spine synapses and synapse development, quantitative electron microscopic methods were use to evaluate synapse density (number of synapses/100 μm2), and the incidence of polyribosome‐containing spines (proportion of spine synapses with underlying polyribosomes) in the neuropil of the dorsal blade of the dentate gyrus at each age. An inverse relationship was found between synapse density and the proportion of spines with polyribosomes. Synapse density increased in an almost linear fashion between 7 and 28 days of age to levels which were actually somewhat higher than in mature rats, whereas the incidence of polyribosome‐containing spines was highest at the youngest ages and decreased with development. Thus, polyribosomes were most prominent under spine synapses during the period of maximal synapse growth. These results, together with our previous observations of increased numbers of polyribosomes under spines during lesion‐induced growth, suggest that the polyribosomes represent a structural specialization of dendrites at sites of synapse construction. We propose that they produce protein(s) that are involved in synapse growth.