大鼠纹状体边缘区P物质样免疫反应神经终末的超微结构研究

ULTRASTRUCTURAL CHARACTERISTICS OF SUBSTANCE P-LIKE IMMUNOREACTIVE TERMINALS IN THE MARGINAL DIVISION OF THE STRIATUM OF THE RAT

边缘区是用免疫组织化学与束路追踪相结合的方法,在大白鼠纹状体发现的一个新区,其间的P物质、脑啡肽等免疫反应神经终末的数量,比纹状体的其他部分多。本文用包埋前免疫电镜方法,研究了该区的P物质免疫反应神经终末的突触特点。发现4种主要的突触类型,最常见的是轴-树和轴-棘突触,几种由两个以上突触组成的复合型突触群也较常见,偶尔可见轴-轴突触。同时也观察到未标记的轴突终末与P物质样免疫反应树突形成突触。P物质样免疫反应轴突终未形成对称型和非对称型突触。非对称型突触、突触后小型树突以及突触构成的复杂性,证明该区的P物质样免疫反应神经终末的来源可能与纹状体其他部位不同,并且提示该区的功能与纹状体其他部分可能不同。

Using the immunohistochemical method combined with tract tracing techniques, a new subdivision, the marginal division, was found in the striatum of the rat. In this subdivision, substance P, enkephaline and dynorphin B terminals were densely localized. The present study investigated the synaptic organization of the substance P-like immunoreactive nerve terminals in the marginal division. Four major types of substance P immunoreactive synapses were identified. Axodendritic and axospinous synapses were the most common ones. Compound synapses with more than two synaptic components were also observed. One axo-axonic synapse was present. Both symmetric and asymmetric substance P-like immunoreactive synapses were seen in the marginal division. The existence of asymmetric synapses, small postsynaptic dendrites and axo-axonic synapses, distinguished the substance P-like immunoreactive nerve terminals in the marginal division from those in the other part of the striatum. The characteristics and complexity of the synaptic organization suggested that the substance P-like immunoreactive nerve terminals in the marginal division probably orginate from a different source and have a different function, as compared to those in the rest part of striatum.