Ballermann Mark, Fouad Karim
Centre for Neuroscience, University of Alberta, Edmonton, Canada, T6G 2G4.
Eur J Neurosci. 2006 Apr;23(8):1988-96. doi: 10.1111/j.1460-9568.2006.04726.x.
Although injured axons in mammalian spinal cords do not regenerate, some recovery of locomotor function following incomplete injury can be observed in patients and animal models. Following a lateral hemisection injury of the thoracic spinal cord, rats spontaneously recover weight-bearing stepping in the hind limb ipsilateral to the injury. The mechanisms behind this recovery are not completely understood. Plasticity in the reticulospinal tract (RtST), the tract responsible for the initiation of walking, has not been studied. In this study, rats received lateral thoracic hemisection of the spinal cord, and RtST projections were compared in two groups of rats, one early in recovery (7 days) and the other at a time point when weight-bearing stepping was fully regained (42 days). We found that this recovery occurs in parallel with increased numbers of collaterals of spared RtST fibers entering the intermediate lamina below the injury at L2. Sprouting of injured RtST fibers above the lesion was not found. In conclusion, our study suggests that sprouting of spared RtST fibers might be involved in the recovery of locomotion following incomplete spinal cord injury.
尽管哺乳动物脊髓中的受损轴突不会再生，但在患者和动物模型中，不完全损伤后仍可观察到运动功能的一些恢复。在胸段脊髓进行半横断损伤后，大鼠会自发恢复损伤同侧后肢的负重行走。这种恢复背后的机制尚未完全了解。负责启动行走的网状脊髓束（RtST）的可塑性尚未得到研究。在本研究中，对大鼠进行胸段脊髓半横断，比较两组大鼠的RtST投射，一组在恢复早期（7天），另一组在完全恢复负重行走时（42天）。我们发现，这种恢复与 spared RtST 纤维进入损伤下方 L2 节段中间层的侧支数量增加同时发生。未发现损伤上方的受损 RtST 纤维发芽。总之，我们的研究表明， spared RtST 纤维的发芽可能参与不完全脊髓损伤后运动功能的恢复。
