de Lima A D, Voigt T
Max-Planck-Institut für Entwicklungsbiologie, Tübingen, Germany.
J Comp Neurol. 1997 Dec 1;388(4):526-40.
Two types of neurons containing gamma-aminobutyric acid (GABA) were identified in cultures of embryonic rat neocortex. Large GABAergic neurons were already present 4 hours after plating, whereas small ones appeared later. Both types were shown to be neurons by double labeling with GABA and microtubule-associated protein 2 (MAP2) immunocytochemistry. The large GABAergic neurons represented less than 5% of the adherent cells, developed neurites rapidly, and progressed synchronously through the polarization and differentiation steps characteristic of the whole neuronal population. During the second week in culture, these GABA-immunoreactive cells developed into large, stellate neurons with fairly homogeneous morphology and poorly ramified, straight dendrites. At the same time, the GABAergic neuropil increased greatly, and neurites of GABAergic neurons showed advancing maturity and smoothness. The axon of each cell covered extensive areas of the culture, frequently encircling the somata of unlabeled neurons in a basket-like fashion. Significant numbers of small GABAergic cells developed only in the absence of the mitotic inhibition routinely used to control glial proliferation. These late-born GABAergic neurons went through neuritogenesis when most of the other neurons were already forming synapses on their somatodendritic surfaces. In mature cultures, they had a multipolar or fusiform morphology with spine-bearing dendrites. They had small somata and were often present inside clusters of neurons. Their short axons showed no obvious basket-like pattern of arborization. Thus, the two types of GABAergic neurons identified in cortical cultures differed in their morphology, distribution, and developmental history. We propose that intercellular interactions during early synaptogenesis may play a role in the development of different morphological types of GABAergic neurons in vitro.
在胚胎大鼠新皮质培养物中鉴定出了两种含有γ-氨基丁酸（GABA）的神经元。接种4小时后就已出现大型GABA能神经元，而小型GABA能神经元出现得较晚。通过GABA与微管相关蛋白2（MAP2）免疫细胞化学双重标记显示，这两种类型的细胞均为神经元。大型GABA能神经元占贴壁细胞的比例不到5%，其神经突迅速生长，并与整个神经元群体极化和分化的特征步骤同步进行。在培养的第二周，这些GABA免疫反应性细胞发育成形态相当均匀、树突分支较少且较直的大型星状神经元。与此同时，GABA能神经毡大量增加，GABA能神经元的神经突成熟度和光滑度不断提高。每个细胞的轴突覆盖了培养物的大片区域，经常以篮状方式环绕未标记神经元的胞体。只有在通常用于控制胶质细胞增殖的有丝分裂抑制不存在的情况下，才会发育出大量小型GABA能细胞。这些晚期生成的GABA能神经元在大多数其他神经元已经在其树突-胞体表面形成突触时才开始进行神经突发生。在成熟培养物中，它们具有多极或梭形形态，有带棘的树突。它们的胞体较小，常常存在于神经元簇内部。它们的短轴突没有明显的篮状分支模式。因此，在皮质培养物中鉴定出的两种类型的GABA能神经元在形态、分布和发育史上存在差异。我们提出，早期突触发生期间的细胞间相互作用可能在体外不同形态类型的GABA能神经元的发育中发挥作用。
