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Synaptic plasticity involving rearrangments of synaptic connections in the sympathetic ganglion

突触可塑性涉及交感神经节突触连接的重新排列

基本信息

批准号：
06808080
负责人：
KAWAI Yoshinori
金额：
$ 1.22万
依托单位：
Wakayama Medical College
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1996
项目状态：
已结题

项目摘要

It has been considered that the sympathetic ganglion is relay station in which synaptic transmission occurs between the principal neurons and the preganglionic axons derived from the thoracic spinal cord. Using an intracellular labeling of the superior cervical ganglion (SCG) neurons with biocytin followed by electron microscopic observation of the synapses involved, I have revealed that dendrites of some SCG neurons serve as not only recipients to the preganglionic axons but also presynaptic elements to other SCG neurons. These dendrodendritic synapses should be considered as an important addition to the conventional scheme as a relay station of the sympathetic ganglion. Since the principal neurons use noradrenaline as a transmitter, these dendrodendritic synapses were interpreted as adrenergic in terms of morphology. I have revealed that in some SCG neurons hyperpolarizations are observed after the preganglionic stimulation and that this synaptically evoked hyperpolarizations are blocked by yohimbine, an alpha2-adrenoceptor antagonist. This result shows that there are adrenergic transmission in the sympathetic ganglion also in terms of pharmacology. Furthermore, these neurons have been clarified to receive dendrodendritic synapses of adrenergic type.These dendrodendritic synapses were observed associated with specialized dendritic morphology, glomerular dendrites. I have got some evidence that these structures may show very acute plasticity. This problem should be addressed in further experiments in the near future.

交感神经节被认为是胸段脊髓的主要神经元和节前轴突之间发生突触传递的中继站。利用细胞内标记的上级颈神经节（SCG）神经元与biocytin，然后通过电子显微镜观察的突触参与，我发现，一些SCG神经元的树突不仅作为受体的节前轴突，但也突触前元件，以其他SCG神经元。这些树-树突触应该被认为是对传统的交感神经节中继站的重要补充。由于主要神经元使用去甲肾上腺素作为递质，这些树-树突触被解释为肾上腺素能的形态。我已经发现，在一些SCG神经元超极化后观察到的节前刺激，这种突触诱发的超极化被育亨宾，α 2-肾上腺素受体拮抗剂。这一结果也从药理学角度说明交感神经节中存在肾上腺素能传递。此外，这些神经元已被澄清接受肾上腺素能型树-树突触。这些树-树突触被观察到与专门的树突形态，肾小球树突。我有一些证据表明这些结构可能表现出非常敏锐的可塑性。这一问题应在不久的将来的进一步实验中加以解决。