Corvaja N, Doucet G, Bolam J P
Départment de Pathologie, Université de Montréal, Québec, Canada.
Neuroscience. 1993 Jul;55(2):417-27. doi: 10.1016/0306-4522(93)90510-m.
A major input to the substantia nigra is from the 5-hydroxytryptamine-containing neurons in the dorsal raphe nucleus. In order to examine the morphology and distribution of this projection, rats were given injections of the anterograde tracers, Phaseolus vulgaris-leucoagglutinin or biocytin, in the dorsal raphe nucleus and the substantia nigra was examined at both the light and electron microscopic levels. In addition, sections of the substantia nigra were immunostained for 5-hydroxytryptamine and examined in both the light and electron microscopes. Since dopaminergic neurons of the substantia nigra are known to be responsive to stimulation of the raphe and to applied 5-hydroxytryptamine, sections that contained anterogradely labelled terminals were further processed to reveal tyrosine hydroxylase immunoreactivity to determine whether the raphe input makes direct synaptic contact with dopaminergic neurons. Light microscopic analysis revealed that all divisions of the substantia nigra received input from the dorsal raphe which, in agreement with previous observations, showed a topographical organization. In that formed asymmetrical synaptic contact with dendritic shafts and spines. The synaptic boutons were often associated with subjunctional dense bodies. Terminals that displayed immunoreactivity for 5-hydroxytryptamine had a similar morphology, synaptic specialisations and postsynaptic targets to the anterogradely labelled terminals. In those sections that were stained for both anterogradely labelled terminals and tyrosine hydroxylase, the raphe-nigral terminals were seen to form asymmetrical synaptic contact with the dendrites of the dopaminergic neurons. It is concluded that dendrites of dopaminergic neurons in the substantia nigra pars reticulata represent at least one of the synaptic targets of the raphe-nigral projection and that these contacts provide an anatomical substrate for the effects of the dorsal raphe, and presumably 5-hydroxytryptamine, on dopaminergic systems in the substantia nigra.
黑质的一个主要输入来自中缝背核中含5-羟色胺的神经元。为了研究该投射的形态和分布，给大鼠在中缝背核注射顺行示踪剂菜豆白细胞凝集素或生物胞素，并在光学显微镜和电子显微镜水平检查黑质。此外，对黑质切片进行5-羟色胺免疫染色，并在光学显微镜和电子显微镜下检查。由于已知黑质的多巴胺能神经元对中缝刺激和应用的5-羟色胺有反应，对含有顺行标记终末的切片进一步处理以显示酪氨酸羟化酶免疫反应性，以确定中缝输入是否与多巴胺能神经元形成直接突触联系。光学显微镜分析显示，黑质的所有部分都接受来自中缝背核的输入，这与先前的观察结果一致，显示出一种拓扑组织。在那里与树突干和棘形成不对称突触联系。突触小体常与突触下致密体相关。显示5-羟色胺免疫反应性的终末与顺行标记终末具有相似的形态、突触特化和突触后靶点。在那些同时对顺行标记终末和酪氨酸羟化酶进行染色的切片中，可见中缝-黑质终末与多巴胺能神经元的树突形成不对称突触联系。得出的结论是，黑质网状部多巴胺能神经元的树突至少是中缝-黑质投射的突触靶点之一，并且这些联系为中缝背核以及推测的5-羟色胺对黑质多巴胺能系统的作用提供了解剖学基础。
