Astrow S H, Qiang H, Ko C P
Department of Biological Sciences, University of Southern California, Los Angeles 90089-2520, USA.
J Neurocytol. 1998 Sep;27(9):667-81. doi: 10.1023/a:1006916232627.
This study aimed to generate a probe for perisynaptic Schwann cells (PSCs) to investigate the emerging role of these synapse-associated glial cells in the formation and maintenance of the neuromuscular junction (NMJ). We have obtained a novel monoclonal antibody, 2A12, which labels the external surface of PSC membranes at the frog NMJ. The antibody reveals PSC fine processes or "fingers" that are interposed between nerve terminal and muscle membrane, interdigitating with bands of acetylcholine receptors. This antibody also labels PSCs at the avian neuromuscular junction and recognizes a 200 kDa protein in Torpedo electric organs. In frog muscles, axotomy induces sprouting of PSC processes beyond clusters of acetylcholine receptors and acetylcholinesterase at denervated junctional branches. PSC branches often extend across several muscle fibers. At some junctions, PSC sprouts join the tips of neighboring branches. The average length of PSC sprouts is approximately 156 microm at 3-week denervated NMJs. PSC sprouting is accompanied by a significant increase in the number of Schwann cell bodies per NMJ. Following nerve regeneration, nerve terminals reinnervate the junction along the PSC processes. In vivo observations of normal frog muscles also show PSC processes longer than nerve terminals at some junctional branches. The results suggest that nerve injury induces profuse PSC sprouting that may play a role in guiding nerve terminal regeneration at frog NMJs. In addition, antibody 2A12 reveals the fine morphology of PSCs in relation to other synaptic elements and is a useful probe in elucidating the function of these synapse-associated glial cells in vivo.
本研究旨在生成一种用于突触周围施万细胞（PSC）的探针，以研究这些与突触相关的神经胶质细胞在神经肌肉接头（NMJ）形成和维持过程中所起的新作用。我们获得了一种新型单克隆抗体2A12，它可标记青蛙NMJ处PSC膜的外表面。该抗体揭示了位于神经末梢和肌膜之间的PSC精细突起或“指状结构”，它们与乙酰胆碱受体带相互交错。这种抗体还可标记禽类神经肌肉接头处的PSC，并识别电鳐电器官中的一种200 kDa蛋白。在青蛙肌肉中，轴突切断术会诱导去神经支配的连接分支处，PSC突起在乙酰胆碱受体和乙酰胆碱酯酶簇之外发生芽生。PSC分支常常延伸穿过几根肌纤维。在一些接头处，PSC芽生与相邻分支的末端相连。去神经支配3周的NMJ处，PSC芽生的平均长度约为156微米。PSC芽生伴随着每个NMJ处施万细胞体数量的显著增加。神经再生后，神经末梢沿着PSC突起重新支配接头。对正常青蛙肌肉的体内观察也显示，在一些连接分支处，PSC突起比神经末梢长。结果表明，神经损伤会诱导大量PSC芽生，这可能在引导青蛙NMJ处神经末梢再生中发挥作用。此外，抗体2A12揭示了PSC与其他突触元件相关的精细形态，是阐明这些与突触相关的神经胶质细胞在体内功能的有用探针。
