大鼠脊髓背角浅层GABA能轴突与SP受体rn阳性神经元的突触联系

摘要

目的：研究大鼠脊髓背角浅层内GABA能神经元与P物质受体(SPR)阳性神经元之间的相互关系.方法：应用SPR包埋前免疫电镜结合GABA胶体金技术.结果：SPR样免疫阳性神经元主要分布于脊髓背角I层和Ⅱ层背侧部的内侧半.电镜下，浅层内SPR样免疫反应阳性产物主要定位于细胞体和树突.免疫反应产物在树突呈片或颗粒状，常常与线粒体外膜表面、粗面内质网、高尔基氏体、树突膜、胞浆膜内面和核膜外表面等相连.双标记显示SPR样免疫反应树突接受GABA样免疫金标记的轴突传入，形成对称性轴-树突触.此外，GABA还可与SPR共存于同一树突中.结论：GABA和P物质受体在脊髓背角神经元的突触联系，为以往GABA调制脊髓伤害感受功能的药理学研究提供了形态学证据.%AIM: To identify synaptic relationship between γaminobutyric acid (GABA)-containing terminals and substance P receptor-positive neurons in the superficial dorsal horn of rat spinal cord. METHODS: A combination of preembedding immunoperoxidase staining for substance P receptor with postembedding immunogold staining for GABA was employed. RESULTS: Intense substance P receptor-expressing neurons were concentrated in medial half of the lamina Ⅰ and the outer lamina Ⅱ of the spinal cord. Under electron microscopy, substance P receptor immunoreactivity was found mainly in perikarya and dendrites, and deposited along neuronal membranes,in Golgi complex, in rough endoplasmic reticulum and on the surface of mitochondria with patch-or granular-like staining. The double-labeling studies revealed that substance P receptor-expressing dendrites received symmetric synaptic contacts from axonal terminals labeled with immunogold particles indicating GABA. GABA also co-localized with substance P receptors in the dendrites.CONCLUSION: The synaptic contact between GABAcontaining terminal and substance P receptor-expressing neuron provided important morphological evidence for previous pharmacological studies concerning antinociceptive function of GABA in the spinal cord.