Gan Wen-Biao, Kwon Elaine, Feng Guoping, Sanes Joshua R, Lichtman Jeff W
Department of Anatomy & Neurobiology, Washington University School of Medicine, 660 South Euclid, Box 8108, St. Louis, Missouri 63110, USA.
Nat Neurosci. 2003 Sep;6(9):956-60. doi: 10.1038/nn1115.
Naturally occurring rearrangements of synaptic terminals are common in the nervous systems of young mammals, but little is known about their incidence in adults. Using transgenic mice that express yellow fluorescent protein (YFP) in axons, we repeatedly imaged nerve terminals in the parasympathetic submandibular ganglion. We found that the pattern of synaptic branches underwent significant rearrangements over several weeks in young adult mice. In older mice, rearrangements were less common, and synaptic patterns on individual neurons were recognizable for many months to years. Axonal branches frequently retracted or extended on a time scale of minutes in young adult mice, but seldom in mature animals. These results provide direct evidence for a decrease in plasticity of interneuronal connections as animals make the transition from young adulthood to middle age. The long-term stability of synaptic patterns could provide a structural basis for the persistence of memory in the adult nervous system.
在幼年哺乳动物的神经系统中，突触终末的自然重排很常见，但对于它们在成年动物中的发生率却知之甚少。利用在轴突中表达黄色荧光蛋白（YFP）的转基因小鼠，我们反复对副交感神经下颌下神经节中的神经终末进行成像。我们发现，在年轻成年小鼠中，突触分支的模式在数周内发生了显著重排。在老年小鼠中，重排则较少见，并且单个神经元上的突触模式在数月至数年的时间里都是可识别的。在年轻成年小鼠中，轴突分支经常在数分钟的时间尺度上回缩或伸展，但在成熟动物中很少见。这些结果为动物从年轻成年期过渡到中年时神经元间连接可塑性的降低提供了直接证据。突触模式的长期稳定性可为成年神经系统中记忆的持久性提供结构基础。
