Cullinan W E, Záborszky L
Department of Otolaryngology, University of Virginia Health Sciences Center, Charlottesville 22908.
J Comp Neurol. 1991 Apr 22;306(4):631-67. doi: 10.1002/cne.903060408.
Axonal projections from hypothalamic nuclei to the basal forebrain, and their relation to cholinergic projection neurons in particular, were studied in the rat by using the anterograde tracer Phaseolus vulgaris-leucoagglutinin (PHA-L) in combination with choline acetyltransferase (ChAT) immunocytochemistry. Discrete iontophoretic PHA-L injections were delivered to different portions of the caudal lateral hypothalamus, as well as to various medial hypothalamic areas, including the ventromedial, dorsomedial, and paraventricular nuclei, and anterior hypothalamic and medial preoptic areas. The simultaneous detection of PHA-L-labeled fibers/terminals and ChAT-positive neurons was performed by using nickel-enhanced diaminobenzidine (DAB) and nonenhanced DAB as chromogens. Selected cases were investigated at the electron microscopic level. Ascending hypothalamic projections maintained an orderly lateromedial arrangement within the different components of the medial forebrain bundle, as well as with respect to their terminal projection fields (e.g., within the bed nucleus of the stria terminalis and lateral septal nucleus). The distribution pattern of hypothalamic inputs to cholinergic projection neurons corresponded to the topography of ascending hypothalamic axons. Axons originating from neurons in the far-lateral hypothalamus reached cholinergic neurons in a zone that extended from the dorsal part of the sublenticular substantia innominata (SI) caudolaterally, to the lateral portion of the bed nucleus of the stria terminalis rostromedially, encompassing a narrow band along the ventral part of the globus pallidus and medial portion of the internal capsule. Axons originating from cells in the medial portion of the lateral hypothalamus reached cholinergic cells primarily in more medial and ventral parts of the SI, and in the magnocellular preoptic nucleus and horizontal limb of the diagonal band nucleus (HDB). Axons from medial hypothalamic cells appeared to contact cholinergic neurons primarily in the medial part of the HDB, and in the medial septum/vertical limb of the diagonal band complex. Electron microscopic double-labeling experiments confirmed contacts between labeled terminals and cholinergic cells in the HDB and SI. Individual hypothalamic axons established synapses with both cholinergic and noncholinergic neuronal elements in the same regions. These findings have important implications for our understanding of the organization of afferents to the basal forebrain cholinergic projection system.
通过使用顺行示踪剂菜豆白细胞凝集素（PHA-L）结合胆碱乙酰转移酶（ChAT）免疫细胞化学技术，在大鼠中研究了下丘脑核向基底前脑的轴突投射，特别是它们与胆碱能投射神经元的关系。将离散的离子电渗法PHA-L注射到尾侧外侧下丘脑的不同部位，以及各种内侧下丘脑区域，包括腹内侧核、背内侧核、室旁核、下丘脑前部和内侧视前区。使用镍增强二氨基联苯胺（DAB）和非增强DAB作为显色剂，同时检测PHA-L标记的纤维/终末和ChAT阳性神经元。对选定的病例进行了电子显微镜水平的研究。下丘脑的上行投射在前脑内侧束的不同组成部分内以及相对于它们的终末投射场（例如，在终纹床核和外侧隔核内）保持有序的外侧到内侧排列。下丘脑对胆碱能投射神经元的输入分布模式与下丘脑上行轴突的拓扑结构相对应。起源于下丘脑最外侧神经元的轴突到达胆碱能神经元的区域，该区域从豆状核下实质（SI）背侧部分向尾外侧延伸，到终纹床核外侧部分向嘴内侧延伸，包括沿着苍白球腹侧部分和内囊内侧部分的一条窄带。起源于下丘脑外侧部内侧细胞的轴突主要到达SI更内侧和腹侧部分、大细胞视前核和斜角带核水平支（HDB）中的胆碱能细胞。来自内侧下丘脑细胞的轴突似乎主要与HDB内侧部分以及内侧隔/斜角带复合体垂直支中的胆碱能神经元接触。电子显微镜双重标记实验证实了标记的终末与HDB和SI中的胆碱能细胞之间的接触。单个下丘脑轴突在同一区域与胆碱能和非胆碱能神经元成分都建立了突触。这些发现对我们理解基底前脑胆碱能投射系统的传入组织具有重要意义。
