Mirsky R, Jessen K R, Schachner M, Goridis C
J Neurocytol. 1986 Dec;15(6):799-815. doi: 10.1007/BF01625196.
There is considerable evidence that the cell surface glycoproteins N-CAM and L1 are important mediators of cell-cell adhesion in the nervous system, at least during development. Numerous studies have been devoted to the molecular properties of these proteins and their adhesion role in embryonic and early postnatal development. Much less is known about their importance in mature tissues. A rigorous and comprehensive description of the cell distribution of these molecules in the adult nervous system would clearly form a useful baseline for functional and biochemical studies. In the present work we have addressed this issue and studied the distribution of N-CAM and L1 throughout adult, as opposed to developing, rat peripheral nervous tissue. Particular attention was paid to the ganglia of the enteric nervous system, since adhesion mechanisms within these ganglia are likely to be placed under unusual demands. We report, for the first time, the presence of N-CAM and L1 on mature sensory, sympathetic and enteric neurons in adult rats. Thus, immunostaining of cell suspensions or short-term cultures showed N-CAM and L1 surface labelling on sympathetic and both large and small dorsal root sensory neurons. Both antigens were also present on the surface of enteric neurons in cultures prepared from 10-day-old rats and neonatal guinea pigs. Immunostaining of sections of enteric ganglia from adults indicated that both molecules were also expressed by mature enteric neurons. In sections of mature sciatic nerve neither N-CAM nor L1 immunoreactivity were detected at the site where the plasma membrane of myelinated axons meets the ad-axonal plasma membrane of the myelin-forming Schwann cell. Thus, both N-CAM and L1 were detected on all major classes of peripheral neurons, while their levels in the plasma membrane of myelinated axons may be significantly down-regulated. Similarly, both N-CAM and L1 were present on all major classes of non-myelin-forming peripheral glia in adult rats. This includes the enteric glial cells of the myenteric ganglia, non-myelin-forming Schwann cells in the sciatic nerve, sympathetic trunk and fine autonomic nerves in the gut wall, and the satellite glial cells of sympathetic and dorsal root sensory ganglia. In contrast, myelin-forming Schwann cells did not express detectable levels of N-CAM and only very low levels of L1, which was mainly located near the nodes of Ranvier.(ABSTRACT TRUNCATED AT 400 WORDS)
有大量证据表明，细胞表面糖蛋白N-CAM和L1是神经系统中细胞间黏附的重要介质，至少在发育过程中是如此。众多研究致力于这些蛋白质的分子特性及其在胚胎期和出生后早期发育中的黏附作用。而关于它们在成熟组织中的重要性却知之甚少。对这些分子在成体神经系统中的细胞分布进行严谨而全面的描述，显然将为功能和生化研究形成一个有用的基线。在本研究中，我们探讨了这个问题，并研究了N-CAM和L1在成年大鼠而非发育中的大鼠外周神经组织中的分布情况。我们特别关注了肠神经系统的神经节，因为这些神经节内的黏附机制可能面临不同寻常的需求。我们首次报道了在成年大鼠的成熟感觉神经元、交感神经元和肠神经元上存在N-CAM和L1。因此，对细胞悬液或短期培养物的免疫染色显示，交感神经元以及大小不同的背根感觉神经元表面有N-CAM和L1标记。在从10日龄大鼠和新生豚鼠制备的培养物中，两种抗原也存在于肠神经元表面。对成年大鼠肠神经节切片的免疫染色表明，成熟的肠神经元也表达这两种分子。在成熟坐骨神经切片中，在有髓轴突的质膜与形成髓鞘的施万细胞的轴突旁质膜相遇的部位，未检测到N-CAM和L1的免疫反应性。因此，在所有主要类型的外周神经元上都检测到了N-CAM和L1，而它们在有髓轴突质膜中的水平可能显著下调。同样，在成年大鼠所有主要类型的非形成髓鞘的外周神经胶质细胞上也都存在N-CAM和L1。这包括肌间神经节的肠胶质细胞、坐骨神经、交感干和肠壁中细小自主神经中的非形成髓鞘的施万细胞，以及交感神经节和背根感觉神经节的卫星胶质细胞。相比之下，形成髓鞘的施万细胞不表达可检测水平的N-CAM，仅表达非常低水平的L1，且主要位于郎飞结附近。（摘要截断于400字）
