Stabilization of axon branch dynamics by synaptic maturation
Stabilization of axon branch dynamics by synaptic maturation
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DOI：
10.1523/jneurosci.0069-06.2006
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发表时间：
2006-03-29
影响因子：
5.3
通讯作者：
Cline, HT
中科院分区：
文献类型：
--
作者：
Ruthazer, ES;Li, JL;Cline, HT
大脑中地形投影的发育细化反映在轴突乔木的动态造型中，轴突乔木随着CNS结构之间的连接形成和成熟而发生。要检查的作用，突触发育和突触成熟的轴突投射的结构发展过程中形成的地形retinotectal投影，我们共表达胞质荧光蛋白（FP）和FP标记的突触素（SYP）在少数视网膜神经节细胞在活的白化病非洲爪蟾蝌蚪揭示标记retinotectal轴突内的突触前位点的分布和动态。双光子延时观察，然后对单个突触处的标记SYP水平进行定量分析，证明了突触发生的时间过程：突触前泪点强度的增加在泪点出现后几分钟内即可检测到，并持续数小时。斑点寿命与其强度相关。此外，我们发现轴突乔木动力学的突触接触的影响。轴突分支回缩过去微弱标记点，但在强烈标记SYP点局部稳定。视觉刺激4小时增强了稳定性的乔木在强烈的突触前点，同时诱导收回的探索分支，只有微弱的标记或没有突触的网站。
The developmental refinement of topographic projections in the brain is reflected in the dynamic sculpting of axonal arbors that takes place as connections between CNS structures form and mature. To examine the role of synaptogenesis and synaptic maturation in the structural development of axonal projections during the formation of the topographic retinotectal projection, we coexpressed cytosolic fluorescent protein (FP) and FP-tagged synaptophysin (SYP) in small numbers of retinal ganglion cells in living albino Xenopus laevis tadpoles to reveal the distribution and dynamics of presynaptic sites within labeled retinotectal axons. Two-photon time-lapse observations followed by quantitative analysis of tagged SYP levels at individual synapses demonstrated the time course of synaptogenesis: increases in presynaptic punctum intensity are detectable within minutes of punctum emergence and continue over many hours. Puncta lifetimes correlate with their intensities. Furthermore, we found that axon arbor dynamics are affected by synaptic contacts. Axon branches retract past faintly labeled puncta but are locally stabilized at intensely labeled SYP puncta. Visual stimulation for 4 h enhanced the stability of the arbor at intense presynaptic puncta while concurrently inducing the retraction of exploratory branches with only faintly labeled or no synaptic sites.