Zhou F C
Department of Anatomy, Indiana University School of Medicine, Indianapolis 46202.
Brain Res Dev Brain Res. 1990 Sep 1;55(2):191-201. doi: 10.1016/0165-3806(90)90200-i.
Laminin has been known to promote neurite outgrowth in culture. We have recently demonstrated that laminin facilitates and guides fiber growth of grafted neurons in the brain. In this study, I report that 4 distinct patterns of laminin immunoreactivity--small and large punctiform laminin, sheath laminin, and somal laminin--were expressed in the brain, each having unique spatial and temporal distributions. They are extensively produced in the developing brain while nerve fibers and vessels are actively growing. Two patterns of laminin, small and large puncta, disappear when the brain matures; the other two, sheath laminin and somal laminin, reduce in intensity but persist through adult life. The small puncta, size less than 1 micron in diameter, frequently accumulated along acellular spaces where future fiber bundles will form, interneuronal spaces and surfaces of neurons where terminal fibers dwell, and around the microvessels where neomicrovessels form. The small puncta, which reportedly appear at the eight-cell stage, were observed in our study at stage E10. They increased in expression from E14 to 19 during the stage when many nerve fibers are navigating to their targets, and subsided in the early postnatal days (P6) when less fiber growth occurs. Large puncta, size about 2 microns in diameter, existed exclusively in the hippocampus. They appeared about E16, and ended P16. The sheath laminin is known to form wrappings on microvessels, the ependymal layer, the choroid plexus, and the surface of the brain. This pattern of laminin attaches to non-neuronal structures which associate with CNS fluid. It was detected at E10 (our youngest group), increased its distribution along with expansion of the associated structure, and persisted throughout the adult life. The somal laminin, associated mainly with the soma of neurons, was the latest appearing laminin pattern (not until E16). It also persisted through adult life in the brain. The somal laminin, which was highly associated with the appearance of neuronal groups in brain nuclei, appeared group by group along with neurons. In summary, laminin attaches with distinct groups of cells in the central nervous system with specific temporal association. This close temporal and spatial association may allow laminin to actively affect nerve growth during brain development. The detailed mapping of laminin distribution is in progress in our lab.
层粘连蛋白已知可促进培养中的神经突生长。我们最近证明，层粘连蛋白可促进并引导脑内移植神经元的纤维生长。在本研究中，我报告了在脑中表达的4种不同模式的层粘连蛋白免疫反应性——小的和大的点状层粘连蛋白、鞘层粘连蛋白和体层粘连蛋白，每种都有独特的空间和时间分布。它们在发育中的大脑中大量产生，此时神经纤维和血管正在积极生长。两种层粘连蛋白模式，小的和大的点状，在大脑成熟时消失；另外两种，鞘层粘连蛋白和体层粘连蛋白，强度降低但在成年期持续存在。小的点状，直径小于1微米，经常聚集在未来纤维束将形成的无细胞空间、中间神经元空间和终末纤维所在的神经元表面以及新微血管形成的微血管周围。据报道在八细胞阶段出现的小的点状，在我们的研究中在E10阶段观察到。它们在许多神经纤维向其靶标导航的阶段从E14到E19表达增加，并在出生后早期（P6）纤维生长较少时消退。大的点状，直径约2微米，仅存在于海马体中。它们大约在E16出现，并在P16结束。已知鞘层粘连蛋白在微血管、室管膜层、脉络丛和脑表面形成包裹。这种层粘连蛋白模式附着于与中枢神经系统液体相关的非神经元结构。它在E10（我们最年轻的组）被检测到，随着相关结构的扩展其分布增加，并在整个成年期持续存在。体层粘连蛋白主要与神经元的胞体相关，是出现最晚的层粘连蛋白模式（直到E16才出现）。它在大脑中也在成年期持续存在。与脑核中神经元群的出现高度相关的体层粘连蛋白，随着神经元逐个出现。总之，层粘连蛋白在中枢神经系统中与不同的细胞群有特定的时间关联附着。这种紧密的时间和空间关联可能使层粘连蛋白在大脑发育过程中积极影响神经生长。我们实验室正在对层粘连蛋白分布进行详细的图谱绘制。
