Synaptic vesicle recycling at two classes of release sites in giant nerve terminals of the embryonic chicken ciliary ganglion.
Synaptic vesicle recycling at two classes of release sites in giant nerve terminals of the embryonic chicken ciliary ganglion.
复制标题
胚胎鸡睫状神经节巨型神经末梢两类释放位点的突触小泡回收。
DOI：
10.1002/cne.10237
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
Sargent,PeterB
中科院分区：
文献类型：
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作者：
Nguyen,Don;Sargent,PeterB
鸡胚睫状神经节中的快速突触传递通过两种不同类型的烟碱乙酰胆碱受体（AChRs）的激活而发生：含有3个亚基的AChRs（3*-AChRs）和含有7个亚基的AChRs（7*-AChRs）。3*-AChR在细胞体上的突触位点处的睫状神经元簇中发现，而7*-AChR在体细胞棘上发现，其历史上被认为在胚胎中没有释放位点。然而，Shoop et al.（Shoop et al. [1999]神经科学杂志。19：692-704）最近描述了在体细胞棘上具有突触前和突触后密度的释放位点。我们用透射电子显微镜比较了棘上的突触部位与细胞光滑表面部分的突触部位的结构。我们发现，这两个群体的网站是相似的活性区长度，囊泡的数量，囊泡和活性区之间的距离。为了研究这些网站的功能特性，我们研究了它们的刺激依赖性摄取和释放的细胞外示踪辣根过氧化物酶（HRP）。我们发现，每一类的释放网站都采取和释放HRP的刺激和钙依赖性的方式。两个群体的标记与示踪剂的突触囊泡的平均分数是相似的，加载后（45%）和卸载后（7%）。因此，我们没有发现这两个解剖学上不同的类的释放网站之间的差异，除了他们的发病率：网站上的棘发生的频率只有12%的细胞体。体细胞棘上的释放位点可能是7*-AChRs引起的突触反应的基础。J. Comp.神经元© 2002 Wiley-Liss，Inc.
Rapid synaptic transmission in the embryonic chicken ciliary ganglion occurs through the activation of two distinct classes of nicotinic acetylcholine receptors (AChRs): those containing 3 subunits (3*-AChRs) and those containing 7 subunits (7*-AChRs). 3*-AChRs are found on ciliary neurons in clusters at synaptic sites on the cell body, whereas 7*-AChRs are found on somatic spines, which historically were thought not to have release sites in the embryo. However, Shoop et al.(Shoop et al.[1999] J. Neurosci. 19: 692–704) recently described release sites having pre-and postsynaptic densities on somatic spines. We used transmission electron microscopy to compare the structure of synaptic sites on spines with those on the smooth surfaced part of the cell. We find that the two populations of sites are similar in active zone length, number of vesicles, and distance between vesicles and active zone. To study the functional properties of these sites, we examined their stimulationdependent uptake and release of the extracellular tracer horseradish peroxidase (HRP). We found that each class of release sites both took up and released HRP in a stimulation-and calcium-dependent manner. The mean fraction of synaptic vesicles labeled with tracer was similar for the two populations, both after loading (45%) and after unloading (7%). Thus we detect no differences between these two anatomically distinct classes of release sites, other than their incidence: sites on spines occurred only 12% as often as those on the cell body. The release sites on somatic spines presumably underlie synaptic responses attributable to 7*-AChRs. J. Comp. Neurol. 448: 128–137, 2002.© 2002 Wiley-Liss, Inc.