Lorenzana Ariana O, Lee Jae K, Mui Matthew, Chang Amy, Zheng Binhai
Department of Neurosciences, University of California San Diego, School of Medicine, La Jolla, CA 92093-0691, USA; Biomedical Sciences Graduate Program, University of California San Diego, School of Medicine, La Jolla, CA 92093-0691, USA.
Department of Neurosciences, University of California San Diego, School of Medicine, La Jolla, CA 92093-0691, USA.
Neuron. 2015 May 20;86(4):947-954. doi: 10.1016/j.neuron.2015.03.061. Epub 2015 Apr 30.
The complex morphology of axons presents a challenge in understanding axonal responses to injury and disease. By in vivo two-photon imaging of spinal dorsal column sensory axons, we systematically examined the effect of injury location relative to the main bifurcation point on axon degeneration and regeneration following highly localized laser injuries. Retrograde but not anterograde degeneration was strongly blocked at the bifurcation point at both the acute and subacute phases. Eliminating either the ascending or descending branch led to a poor regenerative response, while eliminating both led to a strong regenerative response. Thus, a surviving intact branch suppresses both retrograde degeneration and regeneration of the injured branch, thereby preserving the remaining axon architecture. Regenerating axons exhibited a dynamic pattern with alternating phases of regeneration and pruning over a chronic period. In vivo imaging continues to reveal new insights on axonal responses to injury in the mammalian spinal cord.
轴突复杂的形态给理解轴突对损伤和疾病的反应带来了挑战。通过对脊髓背柱感觉轴突进行体内双光子成像，我们系统地研究了损伤位置相对于主要分支点对高度局部激光损伤后轴突退化和再生的影响。在急性期和亚急性期，逆行而非顺行性退化在分支点处均受到强烈阻断。消除上行或下行分支会导致再生反应不佳，而同时消除两者则会导致强烈的再生反应。因此，一个存活的完整分支会抑制受损分支的逆行退化和再生，从而保留剩余的轴突结构。在慢性期，再生轴突呈现出一种动态模式，即再生和修剪阶段交替出现。体内成像不断揭示出关于哺乳动物脊髓中轴突对损伤反应的新见解。
