Annaert W G, Llona I, de Ridder E, Weyns A, Quatacker J, de Potter W P
Department of Medicine, University of Antwerp, Belgium.
Synapse. 1995 Sep;21(1):65-76. doi: 10.1002/syn.890210110.
The subcellular localization of synaptophysin was investigated in noradrenergic nerve terminals of bovine vas deferens and dog spleen and compared with membrane-bound and soluble markers of noradrenergic storage vesicles. At the light microscopical level chromogranin A- and cytochrome b561-immunoreactivity revealed an identical and very dense innervation of the entire vas deferens. In the case of synaptophysin, most immunoreactivity was found only in the outmost varicosities closest to the lumen, which were also positive for chromogranin A. Small dense-core vesicles of dog spleen were purified using a combination of velocity gradient centrifugation and size exclusion chromatography. Small dense-core vesicles were enriched 64 times as measured by the noradrenaline content. Enrichments for dopamine-beta-hydroxylase were in a similar range. Synaptophysin-containing vesicles were smaller in size and they did not contain the typical noradrenergic markers dopamine-beta-hydroxylase, cytochrome b561, and noradrenaline. Instead, they might store adenosine triphosphate (ATP). A greater part of synaptophysin immunoreactivity was consistently found at high sucrose densities at the position of large dense-core vesicles. We conclude that in the noradrenergic nerve terminal: (1) small dense-core vesicles have a membrane composition similar to large dense-core vesicles, indicating that the former are derived from the latter, and (2) synaptophysin seems not to be present on small dense-core vesicles. We suggest the possibility that synaptophysin-containing vesicles form a residual population whose role in neurotransmission has been taken over by large and small dense-core vesicles following noradrenergic differentiation.
在牛输精管和狗脾脏的去甲肾上腺素能神经末梢中研究了突触素的亚细胞定位，并与去甲肾上腺素能储存囊泡的膜结合标记物和可溶性标记物进行了比较。在光学显微镜水平上，嗜铬粒蛋白A和细胞色素b561免疫反应显示整个输精管有相同且非常密集的神经支配。就突触素而言，大多数免疫反应仅在最靠近管腔的最外层膨体中发现，这些膨体对嗜铬粒蛋白A也呈阳性。使用速度梯度离心和尺寸排阻色谱相结合的方法纯化狗脾脏的小致密核心囊泡。通过去甲肾上腺素含量测定，小致密核心囊泡富集了64倍。多巴胺-β-羟化酶的富集程度在相似范围内。含有突触素的囊泡尺寸较小，并且它们不包含典型的去甲肾上腺素能标记物多巴胺-β-羟化酶、细胞色素b561和去甲肾上腺素。相反，它们可能储存三磷酸腺苷（ATP）。在高蔗糖密度下，在大致密核心囊泡的位置始终发现较大部分的突触素免疫反应。我们得出结论，在去甲肾上腺素能神经末梢中：（1）小致密核心囊泡的膜组成与大致密核心囊泡相似，表明前者源自后者，并且（2）突触素似乎不存在于小致密核心囊泡上。我们提出一种可能性，即含有突触素的囊泡形成一个残余群体，在去甲肾上腺素能分化后，其在神经传递中的作用已被大、小致密核心囊泡取代。
