Vitellaro-Zuccarello Laura, Bosisio Paola, Mazzetti Samanta, Monti Claudia, De Biasi Silvia
Dip. Scienze Biomolecolari e Biotecnologie, Università degli Studi di Milano, Via Celoria 26, 20133 Milan, Italy.
Cell Tissue Res. 2007 Mar;327(3):433-47. doi: 10.1007/s00441-006-0289-y. Epub 2006 Oct 12.
We have examined the regional distribution of several chondroitin sulfate proteoglycans (neurocan, brevican, versican, aggrecan, phosphacan), of their glycosaminoglycan moieties, and of tenascin-R in the spinal cord of adult rat. The relationships of these molecules with glial and neuronal populations, identified with appropriate markers, were investigated by using multiple fluorescence labeling combined with confocal microscopy. The results showed that the distribution of the examined molecules was similar at all spinal cord levels but displayed area-specific differences along the dorso-ventral axis, delimiting functionally and developmentally distinct areas. In the gray matter, laminae I and II lacked perineuronal nets (PNNs) of extracellular matrix and contained low levels of chondroitin sulfate glycosaminoglycans (CS-GAGs), brevican, and tenascin-R, possibly favoring the maintenance of local neuroplastic properties. Conversely, CS-GAGs, brevican, and phosphacan were abundant, with numerous thick PNNs, in laminae III-VIII and X. Motor neurons (lamina IX) were surrounded by PNNs that contained all molecules investigated but displayed various amounts of CS-GAGs. Double-labeling experiments showed that the presence of PNNs could not be unequivocally related to specific classes of neurons, such as motor neurons or interneurons identified by their expression of calcium-binding proteins (parvalbumin, calbindin, calretinin). However, a good correlation was found between PNNs rich in CS-GAGs and the neuronal expression of the Kv3.1b subunit of the potassium channel, a marker of fast-firing neurons. This observation confirms the correlation between the electrophysiological properties of these neurons and the specific composition of their microenvironment.
我们研究了几种硫酸软骨素蛋白聚糖（神经聚糖、短蛋白聚糖、多功能蛋白聚糖、聚集蛋白聚糖、磷蛋白聚糖）及其糖胺聚糖部分以及腱生蛋白-R在成年大鼠脊髓中的区域分布。通过使用多重荧光标记结合共聚焦显微镜，研究了这些分子与用适当标记物鉴定的神经胶质细胞和神经元群体之间的关系。结果表明，所检测分子的分布在脊髓各水平相似，但沿背腹轴显示出区域特异性差异，界定了功能和发育上不同的区域。在灰质中，I层和II层缺乏细胞外基质的神经元周围网（PNN），且硫酸软骨素糖胺聚糖（CS-GAGs）、短蛋白聚糖和腱生蛋白-R含量较低，这可能有利于维持局部神经可塑性。相反，CS-GAGs、短蛋白聚糖和磷蛋白聚糖在III-VIII层和X层丰富，有许多粗大的PNN。运动神经元（IX层）被包含所有研究分子但显示不同量CS-GAGs的PNN所包围。双重标记实验表明，PNN的存在与特定类型的神经元，如通过其钙结合蛋白（小白蛋白、钙结合蛋白、钙视网膜蛋白）表达鉴定的运动神经元或中间神经元，并无明确关联。然而，发现富含CS-GAGs的PNN与钾通道Kv3.1b亚基的神经元表达之间存在良好的相关性，钾通道Kv3.1b亚基是快速放电神经元的标志物。这一观察结果证实了这些神经元的电生理特性与其微环境的特定组成之间的相关性。
