Department of Cell and Developmental Biology, College of Graduate Studies, SUNY Upstate Medical University, Syracuse, NY 13210, USA.
Neuroscience. 2010 Oct 27;170(3):971-80. doi: 10.1016/j.neuroscience.2010.06.064. Epub 2010 Jul 24.
We studied the number, location and size of long descending propriospinal tract neurons (LDPT), located in the cervical enlargement (C3-C6 spinal levels), and short thoracic propriospinal neurons (TPS), located in mid-thoracic spinal cord (T5-T7 spinal levels), 2, 6 and 16 weeks following a moderate low thoracic (T9) spinal cord contusion injury (SCI; 25 mm weight drop) and subsequent injections of fluorogold into the upper lumbosacral enlargement (L2-L4 spinal levels). Retrograde labeling showed that approximately 23% of LDPT and 10% of TPS neurons were labeled 2 weeks after SCI, relative to uninjured animals. No additional significant decrease in number of labeled LDPT and TPS cells was found at the later time points examined, indicating that the maximal loss of propriospinal neurons in these two subpopulations occurs within the first 2 weeks post-SCI. The distribution of labeled cells post-moderate SCI was similar to normal in terms of their location within the gray matter. However, there was a significant change in the size (cross sectional area) of labeled neurons following injury, relative to uninjured controls, indicating a loss in the number of the largest class of propriospinal neurons. Interestingly, the number of labeled LDPT and TPS neurons was not significantly different following different injury severities. Although the rostro-caudal extent of the lesion site expanded between 2 and 16 weeks following injury, there was no significant difference in the number of propriospinal neurons that could be retrogradely labeled at these time points. Possible reasons for these findings are discussed.
我们研究了长下行本体感觉传入神经元（LDPT）的数量、位置和大小，这些神经元位于颈膨大部（C3-C6 脊髓水平），以及短胸本体感觉传入神经元（TPS），位于中胸脊髓（T5-T7 脊髓水平），在中度低位胸脊髓（T9）挫伤性损伤（SCI；25mm 重量下降）和随后在腰骶膨大（L2-L4 脊髓水平）注射荧光金后 2、6 和 16 周。逆行标记显示，SCI 后 2 周，约 23%的 LDPT 和 10%的 TPS 神经元被标记，与未受伤动物相比。在以后检查的时间点没有发现标记的 LDPT 和 TPS 细胞数量的进一步显著减少，这表明这两个亚群的本体感觉神经元的最大损失发生在 SCI 后最初的 2 周内。中度 SCI 后标记细胞的分布在灰质内的位置与正常相似。然而，与未受伤对照相比，标记神经元的大小（横截面积）在受伤后发生了显著变化，表明最大类本体感觉神经元数量的减少。有趣的是，标记的 LDPT 和 TPS 神经元的数量在不同的损伤严重程度下没有显著差异。尽管损伤后 2 至 16 周损伤部位的头尾部范围扩大，但在这些时间点可以逆行标记的本体感觉神经元数量没有显著差异。对这些发现的可能原因进行了讨论。
