THE NEURONAL ENDOPLASMIC-RETICULUM - ITS CYTO-CHEMISTRY AND CONTRIBUTION TO THE ENDOMEMBRANE SYSTEM .2. AXONS AND TERMINALS
THE NEURONAL ENDOPLASMIC-RETICULUM - ITS CYTO-CHEMISTRY AND CONTRIBUTION TO THE ENDOMEMBRANE SYSTEM .2. AXONS AND TERMINALS
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DOI：
10.1002/cne.902300208
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发表时间：
1984-01-01
影响因子：
2.5
通讯作者：
CATALDO, AM
中科院分区：
文献类型：
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作者：
BROADWELL, RD;CATALDO, AM
对小鼠脑内不同类型神经元轴突和终末内质网（ER）的形态和细胞化学进行了超微结构观察。神经垂体受到特别关注，因为许多下丘脑-神经垂体轴突的前终末鞘的形态和酶细胞化学活性被慢性盐应激改变。膜对比度和酶细胞化学染色技术被用来表征轴突网状结构，并确定是否细胞器代表溶酶体系统的轴突和管状配置文件参与的原生辣根过氧化物酶（HRP）的顺行轴突运输与ER。轴突ER的潜在酶细胞化学标记物包括葡萄糖-6-磷酸酶（G6 β），硫胺素焦磷酸酶，核苷二磷酸酶和酸性羟化酶活性。HRP的顺行运输进行了分析，在未受损的下丘脑神经垂体神经元和面部和舌下神经运动神经元的小鼠接受蛋白质在侧脑室。内质网遍布轴突，呈平行的，20-40 nm宽的小管，由斜向轴突相互连接。测量的轴突网状物的膜厚度为60-100埃，这与核周内质网相似。在正常条件下，与ER或溶酶体相关的酶细胞化学活性在轴突和末端中并不明显，但在一些轴突和末端前鞘中变得突出，表现出盐应激小鼠神经垂体内的自噬外观。只有G6 β活性是这些轴突和前终末中ER的标记。许多ER配置文件中的非孵育部分和G6 β细胞化学制剂的盐应激神经垂体被包裹或散布在分泌颗粒，多层体和空泡，可能代表形式的溶酶体参与自噬和分泌吞噬。酸水解酶活性定位于空泡内，以及在80-130 nm宽，钝端小管在垂体柄轴突;类似的反应性小管与大的次级溶酶体在神经分泌细胞体汇合，并可能来自这些溶酶体。形态学相同的小管运输HRP在顺行方向观察到只有在盐应激下丘脑神经垂体神经元。HRP阳性小管很可能与溶酶体系统有关。在神经分泌细胞中，也许在一般神经元中，轴突网在其形态、组织和酶细胞化学上与核周ER相似，而不是内膜系统的其他成分。轴突和终末内的ER和溶酶体系统各自代表形态学和细胞化学上不同的亚细胞区室。轴突ER可以是合成代谢隔室，其提供用于形成自噬/分泌吞噬空泡和可能的其他细胞器（即，突触囊泡）。轴突中的溶酶体可能代表一个分解代谢室，其为可能的ER起源的自噬/分泌吞噬空泡提供降解酶。虽然在正常条件下，轴突ER中G6 β活性的细胞化学证据是不存在的，但当存在时，它可能反映了神经元代谢和功能状态的改变。
The morphology and cytochemistry of the endoplasmic reticulum (ER) in axons and terminalis of a number of different types of neurons in brains from mice were investigated ultrastructurally. The neurohypophysis received particular attention because the morphology and enzyme cytochemical activities of many of the preterminal swellings of hypothalamo-neurohypophysial axons are altered by chronic salt-stress. Membrane contrast and enzyme cytochemical staining techniques were employed to characterize the axonal reticulum and to determine if organelles representing the lysosomal system in the axon and the tubular profiles participating in the anterograde axonal transport of native horseradish peroxidase (HRP) are associated with the ER. Potential enzyme cytochemical markers for the axonal ER included glucose-6-phosphatase (G6Pase), thiamine pyrophosphatase, nucleoside diphosphatase and acid hydroxylase activities. The anterograde transport of HRP was analyzed in undamaged hypothalamo-neurohypophysial neurons and in facial and hypoglossal motoneurons of mice receiving the protein in the lateral cerebral ventricle. The ER pervaded the axon and appeared as parallel, 20-40-nm-wide tubules interconnected by oblique anastomoses. Membrane thickness of the axonal reticulum measured 60-100 .ANG., which is similar to that of the perikaryal ER. Enzyme cytochemical activities associated with the ER or lysosomes were not conspicuous in axons and terminals under normal conditions but became prominent in some axons and preterminal swellings manifesting an autophagic appearance within neurohypophyses from salt-stressed mice. Only G6Pase activity was a marker for the ER in these axons and preterminals. Many ER profiles in non-incubated sections and in G6Pase cytochemical preparations of salt-stressed neurohypophyses were wrapped around or interspersed among secretory granules, multilamellar bodies and vacuoles that may represent forms of lysosomes involved in autophagy and crinophagy. Acid hydrolase activities were localized within the vacuoles as well as within 80-130-nm-wide, blunt-ended tubules in pituitary stalk axons; similar reactive tubules were confluent with large secondary lysosomes in neurosecretory cell bodies and may be derived from these lysosomes. Morphologically identical tubules transporting HRP in the anterograde direction were observed only in the salt-stressed hypothalamo-neurohypophysial neuron. The HRP-positive tubules very likely are affiliated with the lysosomal system. In the neurosecretory cell and perhaps in the neuron in general the axonal reticulum is similar in its morphology, organization and enzyme cytochemistry to the perikaryal ER as opposed to other constituents of the endomembrane system. The ER and lysosomal system within the axon and terminals each represents a morphologically and cytochemically distinct subcellular compartment. The axonal ER may be an anabolic compartment that provides membrane or membrane macromolecules for the formation of autophagic/crinophagic vacuoles and possibly other organelles (i.e., synaptic vesicles). Lysosomes in the axon may represent a catabolic compartment that contributes degradative enzymes to the autophagic/crinophagic vacuoles of possible ER origin. Although demonstrable cytochemical evidence for G6Pase activity in the axonal ER is absent under normal conditions, when present it may reflect an alteration in the metabolism and functional state of the neuron.