Zuo Jian, Neubauer Debbie, Graham James, Krekoski Craig A, Ferguson Toby A, Muir David
Department of Neuroscience, University of Florida Brain Institute and College of Medicine, Gainesville, Florida 32610-0296, USA.
Exp Neurol. 2002 Jul;176(1):221-8. doi: 10.1006/exnr.2002.7922.
Our past work indicates that growth-inhibiting chondroitin sulfate proteoglycan (CSPG) is abundant in the peripheral nerve sheaths and interstitium. In this study we tested if degradation of CSPG by chondroitinase enhances axonal regeneration through the site of injury after (a) nerve crush and (b) nerve transection and coaptation. Adult rats received the same injury bilaterally to the sciatic nerves and then chondroitinase ABC was injected near the injury site on one side, and the contralateral nerve was injected with vehicle alone. Nerves were examined 2 days after injury in the nerve crush model and 4 days after injury in the nerve transection model. Chondroitinase-dependent neoepitope immunolabeling showed that CSPG was thoroughly degraded around the injury site in the chondroitinase-treated nerves. Axonal regeneration through the injury site and into the distal nerve was assessed by GAP-43 immunolabeling. Axonal regeneration after crush injury was similar in chondroitinase-treated and control nerves. In contrast, axonal regrowth through the coaptation of transected nerves was markedly accelerated and the ingress of axons into the distal segment was increased severalfold in nerves injected with chondroitinase. On the basis of these results we concluded that growth inhibition by CSPG contributes critically to the poor regenerative growth of axons in nerve transection repair. In addition, degradation of CSPG by injection of chondroitinase ABC at the site of nerve repair increased the ingress of axonal sprouts into basal laminae of the distal nerve segment, presumably by enabling more latitude in growth at the interface of coapted nerve. This suggests that chondroitinase application may be used clinically to improve the outcome of primary peripheral nerve repair.
我们过去的研究表明，具有生长抑制作用的硫酸软骨素蛋白聚糖（CSPG）在周围神经鞘和间质中含量丰富。在本研究中，我们测试了硫酸软骨素酶对CSPG的降解是否能促进轴突在（a）神经挤压伤和（b）神经横断并吻合术后通过损伤部位进行再生。成年大鼠双侧坐骨神经接受相同损伤，然后在一侧损伤部位附近注射硫酸软骨素酶ABC，对侧神经仅注射赋形剂。在神经挤压伤模型中，损伤后2天检查神经；在神经横断模型中，损伤后4天检查神经。硫酸软骨素酶依赖性新表位免疫标记显示，在经硫酸软骨素酶处理的神经中，损伤部位周围的CSPG被彻底降解。通过GAP-43免疫标记评估轴突通过损伤部位并进入远端神经的再生情况。在经硫酸软骨素酶处理的神经和对照神经中，挤压伤后的轴突再生情况相似。相比之下，在注射硫酸软骨素酶的神经中，通过横断神经吻合处的轴突再生明显加速，并且轴突进入远端节段的数量增加了几倍。基于这些结果，我们得出结论，CSPG的生长抑制作用对神经横断修复中轴突的再生不良起着关键作用。此外，在神经修复部位注射硫酸软骨素酶ABC降解CSPG，可能通过使吻合神经界面处的生长有更大的自由度，增加了轴突芽进入远端神经节段基膜的数量。这表明硫酸软骨素酶的应用可能在临床上用于改善原发性周围神经修复的效果。
