Gimenez y Ribotta M G, Roudet C, Sandillon F, Privat A
Plasticite et Vieillissement du Systeme Nerveux, Universite Montpellier II, France.
Brain Res. 1996 Jan 29;707(2):245-55. doi: 10.1016/0006-8993(95)01266-4.
The synaptic connections established by grafted noradrenergic (NA) neurons into the lesioned adult rat spinal cord were analysed using immunocytochemistry at the electron microscopic level. An embryonic cell suspension of the locus coeruleus region from E-13 rat embryos was transplanted into the spinal cord following either: (1) spinal cord transection or (2), partial selective denervation by 6-hydroxy dopamine (6-OH DA). One month after grafting, the NA-neurons established, in the two models, an innervation pattern similar to that found in the intact spinal cord. In both models, the transplanted NA-immunoreactive neurons formed extensive synaptic contacts with dendrites, spines and perikarya. The proportion of axodendritic and axospinous contacts was inverse in the two models. The first model thus reproduced more closely the normal synaptic pattern prefering dendritic targets, which could correspond to a better integration of the graft. In the second model, a partially NA-denervated spinal cord, there existed a competition between residual intrinsic and grafted neuron-derived fibres, which presumably affects synaptogenesis. In conclusion, the present study illustrate the complexity of cell interations conducting to the formation of a specific circuitry. Recognition phenomenon are likely modulated by space constraints, which ultimately shape-up the geometry of synaptic contacts.
利用免疫细胞化学方法在电子显微镜水平分析了移植到成年大鼠脊髓损伤部位的去甲肾上腺素能（NA）神经元所建立的突触连接。将来自E-13大鼠胚胎蓝斑区域的胚胎细胞悬液移植到脊髓中，移植方式如下：（1）脊髓横断；（2）用6-羟基多巴胺（6-OH DA）进行部分选择性去神经支配。移植后1个月，在这两种模型中，NA神经元建立了与完整脊髓中相似的神经支配模式。在这两种模型中，移植的NA免疫反应性神经元与树突、棘突和胞体形成了广泛的突触联系。在这两种模型中，轴突-树突和轴突-棘突联系的比例相反。因此，第一种模型更接近地重现了优先以树突为靶点的正常突触模式，这可能对应于移植组织更好的整合。在第二种模型中，即部分NA去神经支配的脊髓中，残余的固有神经纤维和移植神经元衍生的纤维之间存在竞争，这可能影响突触发生。总之，本研究说明了导致特定神经回路形成的细胞相互作用的复杂性。识别现象可能受到空间限制的调节，而空间限制最终塑造了突触联系的几何形状。
