Wada S, Yone K, Ishidou Y, Nagamine T, Nakahara S, Niiyama T, Sakou T
Department of Orthopaedic Surgery, Faculty of Medicine, Kagoshima University, Sakuragaoka, Japan.
J Neurosurg. 1999 Jul;91(1 Suppl):98-104. doi: 10.3171/spi.1999.91.1.0098.
The aims of this study were to clarify the histological and histochemical changes associated with cell death in the spinal cord after acute traumatic injury and to examine the role of excitatory amino acid release mediated by N-methyl-D-aspartate (NMDA) receptors.
Following laminectomy, the spinal cord in 70 rats was injured at the T-9 level by applying extradural static weight-compression, in which a cylindrical compressor was used to induce complete and irreversible transverse spinal cord injury (SCI) with paralysis of the lower extremities. The injured rats were killed between 30 minutes and 14 days after injury, and the injured cord was removed en bloc. Rats that received NMDA receptor antagonist (MK-801) were killed at the same time points as those that received saline. The specimens were stained with hematoxylin and eosin, Nissl, and Klüver-Barrera Luxol fast blue and subjected to in situ nick-end labeling, a specific in situ method used to allow visualization of apoptosis. Thirty minutes post-SCI, a large hematoma was observed at the compressed segment. Six hours after injury, large numbers of dead cells that were not stained by in situ nick-end labeling were observed. Between 12 hours and 14 days postinjury, nuclei stained by using the in situ nick-end labeling technique were observed not only at the injury site but also in adjoining segments that had not undergone mechanical compression, suggesting that the delayed cell death was due to apoptosis. The number of cells stained by in situ nick-end labeling was maximum at 3 days postinjury. The results of electron microscopic examination were also consistent with apoptosis. In the MK-801-treated rats, the number of cells stained by in situ nick-end labeling was smaller than in nontreated rats at both 24 hours and 7 days after injury.
These findings suggest that NMDA-receptor activation promotes delayed neuronal and glial cell death due to apoptosis.
本研究的目的是阐明急性创伤性损伤后脊髓中与细胞死亡相关的组织学和组织化学变化，并研究由N-甲基-D-天冬氨酸（NMDA）受体介导的兴奋性氨基酸释放的作用。
椎板切除术后，用硬膜外静态重物压迫法在70只大鼠的T-9水平损伤脊髓，使用圆柱形压迫器诱导完全不可逆的横贯性脊髓损伤（SCI）并导致下肢瘫痪。受伤大鼠在受伤后30分钟至14天内处死，将受伤的脊髓整块取出。接受NMDA受体拮抗剂（MK-801）的大鼠与接受生理盐水的大鼠在相同时间点处死。标本用苏木精和伊红、尼氏染色、克吕弗-巴雷拉鲁戈尔斯坚牢蓝染色，并进行原位缺口末端标记，这是一种用于可视化凋亡的特异性原位方法。脊髓损伤后30分钟，在受压节段观察到一个大血肿。损伤后6小时，观察到大量未被原位缺口末端标记染色的死亡细胞。在受伤后12小时至14天之间，不仅在损伤部位，而且在未经历机械压迫的相邻节段都观察到使用原位缺口末端标记技术染色的细胞核，这表明延迟性细胞死亡是由于凋亡所致。原位缺口末端标记染色的细胞数量在受伤后3天达到最大值。电子显微镜检查结果也与凋亡一致。在MK-801处理的大鼠中，受伤后24小时和7天时，原位缺口末端标记染色的细胞数量均少于未处理的大鼠。
这些发现表明，NMDA受体激活通过凋亡促进延迟性神经元和胶质细胞死亡。
