McLaren J, Brawer J R, Schipper H M
Department of Anatomy, McGill University, Montreal, Quebec, Canada.
J Histochem Cytochem. 1992 Dec;40(12):1887-97. doi: 10.1177/40.12.1453006.
A subpopulation of astrocytes in periventricular brain regions and in cysteamine-treated neuroglial cultures contains cytoplasmic granules that exhibit an affinity for Gomori stains, orange-red autofluorescence, and non-enzymatic peroxidase activity. The autofluorescence and pseudoperoxidase activity are consistent with the presence of porphyrins and heme iron, respectively. In the present study, we employed diaminobenzidine cytochemistry, transmission electron microscopy, and energy-dispersive X-ray microanalysis (electron microprobe) in an attempt to correlate fine structure with the peroxidase activity and elemental composition of the cysteamine-induced inclusions in cultured astrocytes. In osmicated preparations, these membrane-bound inclusions varied greatly in size, were round or ovoid in shape, and exhibited an intensely electron-dense granular matrix. In non-osmicated preparations, many inclusions exhibited internal membranous partitions producing complex subcompartmentalization. Diaminobenzidine reaction product, indicative of endogenous peroxidase activity, was occasionally observed distributed diffusely throughout the granule matrix. More commonly, peroxidase activity was restricted to specific intraorganellar compartments. Elemental iron was detected in the inclusions by electron microprobe analysis. The presence and concentration of iron in these organelles correlated closely with the presence and intensity of diaminobenzidine staining, suggesting that redox-active iron mediates the pseudoperoxidase reactions in these cells. Cysteamine-induced derangements of porphyrin-heme biosynthesis may be responsible for the proliferation of iron-containing gliosomes in these astrocytes.
脑室周围脑区和经半胱胺处理的神经胶质细胞培养物中的星形胶质细胞亚群含有胞质颗粒，这些颗粒对Gomori染色具有亲和力，呈现橙红色自发荧光和非酶促过氧化物酶活性。自发荧光和假过氧化物酶活性分别与卟啉和血红素铁的存在一致。在本研究中，我们采用二氨基联苯胺细胞化学、透射电子显微镜和能量色散X射线微分析（电子微探针），试图将精细结构与培养的星形胶质细胞中半胱胺诱导的包涵体的过氧化物酶活性和元素组成相关联。在经锇酸处理的标本中，这些膜结合的包涵体大小差异很大，呈圆形或椭圆形，呈现出强烈的电子致密颗粒基质。在未经锇酸处理的标本中，许多包涵体呈现出内部膜性分隔，产生复杂的亚区室化。偶尔观察到指示内源性过氧化物酶活性的二氨基联苯胺反应产物弥漫分布于整个颗粒基质中。更常见的是，过氧化物酶活性局限于特定的细胞器内区室。通过电子微探针分析在包涵体中检测到元素铁。这些细胞器中铁的存在和浓度与二氨基联苯胺染色的存在和强度密切相关，表明具有氧化还原活性的铁介导了这些细胞中的假过氧化物酶反应。半胱胺诱导的卟啉-血红素生物合成紊乱可能是这些星形胶质细胞中含铁胶质体增殖的原因。
