Keirstead H S, Dyer J K, Sholomenko G N, McGraw J, Delaney K R, Steeves J D
Department of Zoology, University of British Columbia, Vancouver, Canada.
J Neurosci. 1995 Oct;15(10):6963-74. doi: 10.1523/JNEUROSCI.15-10-06963.1995.
Transections of the chicken spinal cord after the developmental onset of myelination at embryonic day (E) 13 results in little or no functional regeneration. However, intraspinal injection of serum complement proteins with complement-binding GalC or 04 antibodies between E9-E12 results in a delay of the onset of myelination until E17. A subsequent transection of the spinal cord as late as E15 (i.e., during the normal restrictive period for repair) results in neuroanatomical regeneration and functional recovery. Utilizing a similar immunological protocol, we evoked a transient alteration of myelin structure in the posthatching (P) chicken spinal cord, characterized by widespread "unravelling" of myelin sheaths and a loss of MBP immunoreactivity (myelin disruption). Myelin repair began within 7 d of cessation of the myelin disruption protocol. Long term disruption of thoracic spinal cord myelin was initiated after a P2-P10 thoracic transection and maintained for > 14 d by intra-spinal infusion of serum complement proteins plus complement-binding GalC or 04 antibodies. Fourteen to 28 d later, retrograde tract tracing experiments, including double-labeling protocols, indicated that approximately 6-19% of the brainstem-spinal projections had regenerated across the transection site to lumbar levels. Even though voluntary locomotion was not observed after recovery, focal electrical stimulation of identified brainstem locomotor regions evoked peripheral nerve activity in paralyzed preparations, as well as leg muscle activity patterns typical of stepping in unparalyzed animals. This indicated that a transient alteration of myelin structure in the injured adult avian spinal cord facilitated brainstem-spinal axonal regrowth resulting in functional synaptogenesis with target neurons.
在胚胎第13天（E13）髓鞘形成开始发育后切断鸡的脊髓，几乎不会导致功能再生或根本不会导致功能再生。然而，在E9 - E12期间向脊髓内注射结合补体的半乳糖脑苷脂（GalC）或O4抗体的血清补体蛋白，会使髓鞘形成开始延迟至E17。随后在E15（即正常修复限制期内）切断脊髓，会导致神经解剖学上的再生和功能恢复。利用类似的免疫方案，我们在孵化后（P）的鸡脊髓中引发了髓鞘结构的短暂改变，其特征是髓鞘广泛“解开”以及髓鞘碱性蛋白（MBP）免疫反应性丧失（髓鞘破坏）。髓鞘修复在髓鞘破坏方案停止后的7天内开始。在P2 - P10进行胸段脊髓横断后开始对胸段脊髓髓鞘进行长期破坏，并通过脊髓内输注血清补体蛋白加结合补体的GalC或O4抗体维持超过14天。十四至二十八天后，逆行束路追踪实验，包括双标记方案，表明约6 - 19%的脑干 - 脊髓投射已穿过横断部位再生至腰段水平。尽管恢复后未观察到自主运动，但对已确定的脑干运动区域进行局部电刺激可在瘫痪的标本中诱发外周神经活动，以及在未瘫痪动物中典型的踏步腿部肌肉活动模式。这表明成年鸟类受损脊髓中髓鞘结构的短暂改变促进了脑干 - 脊髓轴突再生，导致与靶神经元形成功能性突触。
