Lavoie B, Parent A
Centre de Recherche en Neurobiologie, Hôpital de l'Enfant-Jésus, Québec, Canada.
J Comp Neurol. 1994 Jun 8;344(2):232-41. doi: 10.1002/cne.903440205.
The distribution and chemospecificity of the pedunculonigral neurons have been studied in squirrel monkeys (Saimiri sciureus) with cholera toxin subunit B (CTb) and fluorogold (FG) as retrograde tracers combined with immunohistochemistry for choline acetyltransferase (ChAT), glutamate, and the calcium binding protein calbindin D-28k. The injection of either CTb or FG into the substantia nigra produces prominent retrograde cell labeling in the mesopontine tegmentum. Labeled neurons are particularly numerous at the level of the decussation of the superior cerebellar peduncle, where they abound principally in the pars dissipata of the pedunculopontine nucleus (PPN). A significant proportion of retrogradely labeled neurons in the PPN display ChAT immunoreactivity. Within the entire PPN, approximately 25% of the retrogradely labeled neurons express ChAT immunoreactivity, but proportions of doubly labeled neurons are about 35%, 25%, and 15% in the rostral, middle, and caudal thirds of the PPN, respectively. These doubly labeled neurons are scattered among numerous retrogradely labeled neurons that are ChAT-negative and whose number increases along the rostrocaudal extent of the PPN. Several retrogradely labeled neurons in the PPN display glutamate immunoreactivity, but very few express calbindin. This study provides the first direct evidence for the involvement of cholinergic and glutamatergic neurons in the pedunculonigral projection in primates. Furthermore, the fact that some neurons of the PPN display both ChAT and glutamate immunoreactivity indicates that single neurons in the mesopontine tegmentum may exert a two-fold effect upon dopaminergic neurons of the substantia nigra. This dual cholinergic and glutamatergic pedunculonigral projection may play a crucial role in the functional organization of primate basal ganglia.
利用霍乱毒素B亚基（CTb）和荧光金（FG）作为逆行示踪剂，并结合胆碱乙酰转移酶（ChAT）、谷氨酸和钙结合蛋白钙结合蛋白D - 28k的免疫组织化学方法，对松鼠猴（Saimiri sciureus）中脑脚内核神经元的分布和化学特异性进行了研究。将CTb或FG注入黑质后，在脑桥中脑被盖区产生明显的逆行细胞标记。标记的神经元在小脑上脚交叉水平特别多，主要集中在脚桥核（PPN）的弥散部。PPN中相当一部分逆行标记的神经元显示ChAT免疫反应性。在整个PPN内，约25%的逆行标记神经元表达ChAT免疫反应性，但在PPN的头端、中间和尾端三分之一中，双标记神经元的比例分别约为35%、25%和15%。这些双标记神经元散布在众多ChAT阴性的逆行标记神经元中，且其数量沿PPN的头尾方向增加。PPN中的一些逆行标记神经元显示谷氨酸免疫反应性，但很少表达钙结合蛋白。本研究首次直接证明了胆碱能和谷氨酸能神经元参与灵长类动物的脚内核投射。此外，PPN的一些神经元同时显示ChAT和谷氨酸免疫反应性这一事实表明，脑桥中脑被盖区的单个神经元可能对黑质的多巴胺能神经元产生双重作用。这种双重的胆碱能和谷氨酸能脚内核投射可能在灵长类动物基底神经节的功能组织中起关键作用。
