Pearson H E, Stoffler D J, Sonstein W J
Department of Anatomy and Cell Biology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140.
J Comp Neurol. 1992 Jan 15;315(3):333-43. doi: 10.1002/cne.903150308.
We have used the neurotoxin kainic acid to produce rapid degeneration of neurons in the dorsal lateral geniculate nucleus (dLGN) of the adult cat. This degeneration mimics the rapid loss of geniculate neurons seen after visual cortex ablation in the neonate. Subsequent anterograde transport of horseradish peroxidase injected into the eye was used to reveal the projection patterns of retinal ganglion cell axons at different survival periods after the kainic acid injection. The density of retinal projections to the degenerated regions of the geniculate was reduced considerably at 4 and 6 months survival, but at 2 months was not significantly different from normal. The laminar pattern of projections to degenerated regions of the geniculate did not change in any animals studied, even when an adjacent lamina contained surviving cells. Electron microscopic examination of degenerated dLGN revealed intact retinal (RLP) and RSD terminals at all survival times, although the density of terminals appeared much reduced when compared to controls. Some RLP terminals exhibited the "dark reaction" of degeneration and these degenerating terminals were most numerous at 2 months survival. These findings demonstrate that, in response to degeneration of their usual target cells, mature retinal ganglion cells with withdraw their axon terminals from these regions of degeneration. We conclude that mature retinal ganglion cells continue to be dependent on target integrity for the maintenance of a normal axonal arborization.
我们使用神经毒素海藻酸来促使成年猫背外侧膝状核（dLGN）中的神经元快速退化。这种退化模拟了新生猫视觉皮层切除后膝状神经元的快速丧失。随后，将辣根过氧化物酶注入眼睛，利用其顺行运输来揭示海藻酸注射后不同存活期视网膜神经节细胞轴突的投射模式。在存活4个月和6个月时，投射到膝状核退化区域的视网膜密度显著降低，但在2个月时与正常情况无显著差异。在所有研究的动物中，投射到膝状核退化区域的分层模式均未改变，即使相邻层含有存活细胞。对退化的dLGN进行电子显微镜检查发现，在所有存活时间点，视网膜（RLP）和RSD终末均保持完整，尽管与对照组相比，终末密度似乎大幅降低。一些RLP终末表现出退化的“暗反应”，这些退化的终末在存活2个月时数量最多。这些发现表明，成熟的视网膜神经节细胞会对其通常靶细胞的退化做出反应，从这些退化区域撤回其轴突终末。我们得出结论，成熟的视网膜神经节细胞在维持正常轴突分支方面仍然依赖于靶细胞的完整性。
