Firkins S S, Bates C A, Stelzner D J
Department of Anatomy and Cell Biology, State University of New York, Syracuse 13210.
Exp Neurol. 1993 Mar;120(1):1-15. doi: 10.1006/exnr.1993.1036.
We have investigated corticospinal (CS) axon growth around cervical spinal injury in the neonatal rat and related this growth to the astroglial reaction occurring at the lesion site. Rats received a high cervical overhemisection (left dorsal funiculotomy, right spinal hemisection) and a right cortical ablation on Postnatal Days (PNDs) 0, 3, 6, 12, and 21 to 24 (weanlings). In chronic operates the remaining CS projection from the left sensorimotor cortex was then assayed using wheat germ agglutinin-horseradish peroxidase as an anterograde tracer. In other operates the formation of the astroglial scar at the spinal lesion site was studied using a monoclonal antibody to glial fibrillary acidic protein. In PNDs 0-6 operates labeled axons extend through the intact left hemicord to bypass the lesion. The labeled axons travel to the edge of the lesion, cross the midline, and pass lateral to the lesion within the dorsal and intermediate gray and dorsal lateral white matter. Axons project bilaterally to normal areas of CS termination in PND 0 operates for a distance of 2.5 to 4 spinal segments caudal to the lesion which decreases to 1.5 to 2 segments in PND 6 operates. In PND 12 and weanling operates labeled fibers do not grow around the lesion but instead are retracted rostrally. There is an astrocytic reaction to injury at all ages by 3 days postoperatively (p.o.) that becomes greater with age and p.o. survival time. A more complicated cystic scar forms in 6-day and older operates. These data show that there is an age-related change in the ability of CS axons to grow around spinal injury which ends near the time CS elongation and gliogenesis is complete in the spinal cord.
我们研究了新生大鼠颈髓损伤周围皮质脊髓（CS）轴突的生长情况，并将这种生长与损伤部位发生的星形胶质细胞反应联系起来。在出生后第0、3、6、12天以及21至24天（断奶期），给大鼠进行高颈段半横断（左侧背侧索切开术，右侧脊髓半横断）和右侧皮质切除术。在慢性手术组中，然后使用小麦胚凝集素 - 辣根过氧化物酶作为顺行示踪剂，检测左侧感觉运动皮质剩余的CS投射。在其他手术组中，使用针对胶质纤维酸性蛋白的单克隆抗体研究脊髓损伤部位星形胶质瘢痕的形成。在出生后第0 - 6天的手术中，标记的轴突穿过完整的左侧半脊髓以绕过损伤部位。标记的轴突延伸至损伤边缘，穿过中线，并在背侧和中间灰质以及背外侧白质内在损伤部位的外侧通过。在出生后第0天的手术中，轴突双侧投射至CS正常终止区域，在损伤部位尾侧2.5至4个脊髓节段的距离内，而在出生后第6天的手术中，该距离减少至1.5至2个节段。在出生后第12天和断奶期的手术中，标记的纤维不在损伤部位周围生长，而是向头侧回缩。术后3天（p.o.）所有年龄段均出现对损伤的星形细胞反应，且随着年龄和术后存活时间的增加而增强。在6天及以上的手术中形成更复杂的囊性瘢痕。这些数据表明，CS轴突在脊髓损伤周围生长的能力存在与年龄相关的变化，这种变化在脊髓中CS伸长和胶质细胞生成完成时接近尾声。
