Ramakers G J, Verhaagen J, Oestreicher A B, Margolis F L, van Bergen en Henegouwen P M, Gispen W H
Rudolf Magnus Institute, University of Utrecht, The Netherlands.
J Neurocytol. 1992 Dec;21(12):853-69. doi: 10.1007/BF01191683.
Because the growth-associated protein B-50 (GAP-43) has been implicated in neurite outgrowth as well as in synaptic plasticity, we studied its light and electron microscopical distribution in the mouse olfactory bulb, an area of the nervous system which exhibits a high degree of synaptic plasticity. Immunofluorescent staining with monospecific affinity-purified anti-B-50 antibodies revealed that B-50 is most abundantly expressed in the olfactory nerve fibre layer and the granule cell layer neuropil, while little staining was observed in the external plexiform layer and in cell bodies. B-50 is absent from dendrites and myelinated axons as indicated by double labelling with monoclonal antibodies against microtubule-associated protein 2 and the large neurofilament protein, respectively. Using post-embedding immunogold labelling on ultrathin Lowicryl sections, B-50 was found to be highly concentrated in presumed growth cones in the olfactory nerve fibre layer and in thin unmyelinated axons and presynaptic terminals in the granule cell layer neuropil. Near background immunolabelling was seen in perikarya, dendrites and myelinated axons. In view of the implication of B-50 in plasticity-related phenomena, its abundance in the thin unmyelinated preterminal axons suggests that these are potential sites of extrasynaptic plasticity.
由于生长相关蛋白B - 50（GAP - 43）与神经突生长以及突触可塑性有关，我们研究了它在小鼠嗅球中的光镜和电镜分布，嗅球是神经系统中一个具有高度突触可塑性的区域。用单特异性亲和纯化的抗B - 50抗体进行免疫荧光染色显示，B - 50在嗅神经纤维层和颗粒细胞层神经毡中表达最为丰富，而在外丛状层和细胞体中观察到的染色很少。分别用针对微管相关蛋白2和大神经丝蛋白的单克隆抗体进行双重标记表明，树突和有髓轴突中不存在B - 50。在超薄Lowicryl切片上进行包埋后免疫金标记，发现B - 50高度集中在嗅神经纤维层的假定生长锥以及颗粒细胞层神经毡中的细无髓轴突和突触前终末。在核周体、树突和有髓轴突中可见接近背景水平的免疫标记。鉴于B - 50与可塑性相关现象有关，它在细无髓终末前轴突中的丰富表明这些是突触外可塑性的潜在位点。
