Knyihár-Csillik E, Török A
Department of Anatomy, Albert Szent-Györgyi Medical University, Szeged, Hungary.
Neuroscience. 1989;33(1):75-91. doi: 10.1016/0306-4522(89)90312-6.
Reorganization of synaptic circuitry has been studied in the upper dorsal horn (Lamina II, substantia gelatinosa Rolandi) of the lumbar spinal cord in the adult rat, by means of electron histochemical visualization of thiamine monophosphatase after transganglionic degenerative atrophy. Thiamine monophosphatase, a highly specific and selective marker of Type C (small) dorsal root neurons, was demonstrated at light and electron microscopic levels by means of a Gömöri-type cytochemical reaction, using thiamine monophosphate chloride (Sigma) as substrate and Pb2+ as a capturing agent. Transganglionic degenerative atrophy, induced by a crush injury of the sciatic nerve, results in partial depletion of thiamine monophosphatase from ipsilateral segments L2-S1. The extent of depletion was determined in a complete series of frozen cross-sections, by means of measuring the projections of active and depleted areas and their distances from the midline. Values were fed into a personal computer and maps demonstrating the distribution of intact and impaired areas were generated. The V-shaped area of depletion starts to shrink due to incipient regeneration on the 23rd postoperative day, in caudorostral and mediolateral gradients. Replenishment of thiamine monophosphatase is completed on the 60th postoperative day. Electron microscopic cytochemistry revealed the presence of the thiamine monophosphatase reaction end product in axonal growth cones, filopodia, young axons and their varicous swellings that are transformed into scallopped en passant terminals in the later course of regeneration. Axonal growth cones and regenerating sprouts undergo Wallerian degeneration and simultaneous redepletion of the marker enzyme after transection of dorsal roots L3, L4 and L5. Thiamine monophosphatase, located initially within the axoplasms of regenerating fibers, is successively translocated to the external axolemmal surfaces. Functional maturity of the terminals is achieved only later. The resulting redundant and transient wiring is thinned out in a following maturation period, in a manner resembling the sequence of events in embryonic development. The regenerative potency of central terminals of primary sensory neurons is not restricted to a single regeneration. By repeatedly crushing the sciatic nerve, four successive degenerative-regenerative cycles have been evoked, resulting in replenishment of the marker enzyme thiamine monophosphatase.
通过跨神经节变性萎缩后硫胺单磷酸酶的电子组织化学可视化，对成年大鼠腰脊髓上背角（II层，罗蓝氏胶状质）的突触回路重组进行了研究。硫胺单磷酸酶是C型（小）背根神经元的一种高度特异性和选择性标记物，通过Gömöri型细胞化学反应，以氯化硫胺单磷酸（Sigma）为底物，Pb2+为捕获剂，在光镜和电镜水平上进行了显示。坐骨神经挤压伤诱导的跨神经节变性萎缩导致同侧L2 - S1节段硫胺单磷酸酶部分缺失。通过测量活跃区和缺失区的投影及其与中线的距离，在一系列完整的冰冻横切面上确定缺失程度。将数据输入个人计算机，生成显示完整和受损区域分布的图谱。由于术后第23天开始再生，缺失的V形区域开始在尾头和中外侧梯度上收缩。术后第60天硫胺单磷酸酶补充完成。电子显微镜细胞化学显示，硫胺单磷酸酶反应终产物存在于轴突生长锥、丝状伪足、幼嫩轴突及其膨体中，在再生后期这些膨体转变为扇贝状的旁分泌终末。切断L3、L4和L5背根后，轴突生长锥和再生芽经历华勒变性，标记酶同时再次缺失。最初位于再生纤维轴质内的硫胺单磷酸酶相继转移到轴突外膜表面。终末的功能成熟仅在稍后实现。在随后的成熟期，多余的临时布线以类似于胚胎发育中事件顺序的方式逐渐减少。初级感觉神经元中枢终末的再生能力不限于单次再生。通过反复挤压坐骨神经，引发了四个连续的变性 - 再生周期，导致标记酶硫胺单磷酸酶的补充。
