三叉神经尾侧脊束核内P物质纤维终末的超微结构

The Ultrastructure of Substance P Fibers and Terminals in Spinal Trigeminal Caudal Subnucleus

目的 进一步探讨三叉神经尾侧脊束核内SP免疫反应阳性纤维在感觉传递中的可能作用。方法 SP采用免疫细胞化学方法和电子显微镜方法 ,观察大鼠三叉神经尾侧脊束核内SP阳性标记纤维的超微结构和突触联系。结果 SP轴突终末分布于树突间 ,这些轴突终末含有大量的透明小泡、少量大致密芯小泡和线粒体。经过秋水仙素处理后 ,可见到SP免疫反应阳性树突。多数SP轴突终末与非标记树突 ,以及个别SP轴突终末与SP树突形成轴 树突触。含SP的突触复合体较为多见 ,为会聚型。其中可见SP轴突终末与中心的非标记树突形成GrayⅡ型轴 树突触 ;另有非标记的轴突终末与中心SP树突形成 (扁平小泡形 )F型轴 树突触。结论 三叉神经尾侧脊束核接受多种纤维传入 ,SP纤维只是多种传入纤维中的一种。形态学证明 ,在痛调制活动中 ,三叉神经尾侧脊束核内有SP纤维构成的突触后抑制类型 (GrayⅡ )突触参与。

Objective To explore futher the possible action of substance P (SP) fibers (SP) to spinal trigeminal caudal subnucleus (Vc) on the sensory neurotransmission. Methods The ultrastructure and synaptic relationships of the SP fibers were observed by using immunocytochemical and electron microscopical methods. Results The SP axonal terminals, which contain a lot of small clear vesicles?a few of large dense cored vesicles and mitochondria, are distributed among the dendrites. After pretreatment of colchicine, the SP dendrites can be observed. Majority of the SP axon terminals form axodendritic synapses with unlabelled dendrites or with SP dendrites occasionally. There are many converging synaptic complexes in the Vc. In the complexes SP axon terminals form axodendritic synapses with central unlabelled dendrites, some of them belong to type Ⅱ synapses, or unlabelled axon terminals form axodendritic synapses with central SP dendrites, some of them belong to type F. Conclusion The Vc receives different afferent fibers including SP fibers. In the pain mediation activity, there are postsynaptic inhibitory synapses (Gray Ⅱ type) in which SP fibers take part.