Berendse H W, Groenewegen H J, Lohman A H
Department of Anatomy and Embryology, Vrije Universiteit, Amsterdam, The Netherlands.
J Neurosci. 1992 Jun;12(6):2079-103. doi: 10.1523/JNEUROSCI.12-06-02079.1992.
The ventral striatum is characterized by an intricate neurochemical compartmentation that is reflected in the distribution of most of its afferent fiber systems. In the present study, the compartmental relationships of ventral striatal neurons projecting to the mesencephalon were studied by combining tract tracing with the immunohistochemical localization of leu-enkephalin. Injections of the retrograde tracer cholera toxin subunit B were placed at various sites in the ventral mesencephalon. The anterograde tracer Phaseolus vulgaris leucoagglutinin was injected in single compartments in the rostrolateral part of the nucleus accumbens. The projections from the ventral striatum to the dopaminergic cell groups in the ventral mesencephalon and those to the substantia nigra pars reticulata originate from distinct subpopulations of ventral striatal neurons that respect neurochemically defined compartmental boundaries. In the "shell" of the nucleus accumbens, neurons that project to the dopaminergic cell groups are located outside areas of high cell density and weak enkephalin immunoreactivity (ENK-IR). Rostrolaterally in the "core" of the nucleus accumbens, neurons inside large areas of strong ENK-IR surrounding the anterior commissure project to the dorsomedial part of the substantia nigra pars reticulata, whereas neurons outside these areas innervate the ventral tegmental area and/or the medial part of the substantia nigra pars compacta. By contrast, more caudally in the dorsal part of the nucleus accumbens and in the ventral part of the caudate-putamen, the relationships are reversed: neurons in- or outside small patches of strong ENK-IR project respectively to the pars compacta or the pars reticulata of the substantia nigra. Since the thalamic and cortical afferents of the ventral striatum are compartmentally ordered as well, the present results imply that through the ventral striatal compartments information from disparate combinations of cortical and thalamic sources may be conveyed to distinct mesencephalic targets. The component of the ventral striatomesencephalic system reaching the dopaminergic cell groups A10, A9, and A8 may modulate the dopaminergic input to virtually the entire striatum. The other component can, by way of the pars reticulata of the substantia nigra, participate in nigrothalamic and nigrotectal output pathways of the basal ganglia.
腹侧纹状体的特点是具有复杂的神经化学分区，这在其大多数传入纤维系统的分布中得以体现。在本研究中，通过将束路追踪与亮脑啡肽的免疫组织化学定位相结合，研究了投射至中脑的腹侧纹状体神经元的分区关系。将逆行示踪剂霍乱毒素B亚单位注射到腹侧中脑的不同部位。将顺行示踪剂菜豆凝集素注射到伏隔核 rostrolateral 部分的单个分区中。从腹侧纹状体到腹侧中脑多巴胺能细胞群以及到黑质网状部的投射，源自腹侧纹状体神经元的不同亚群，这些亚群遵循神经化学定义的分区边界。在伏隔核的“壳”中，投射至多巴胺能细胞群的神经元位于细胞密度高且脑啡肽免疫反应性（ENK-IR）弱的区域之外。在伏隔核“核心”的 rostrolateral 部位，围绕前连合的大片强 ENK-IR 区域内的神经元投射至黑质网状部的背内侧部分，而这些区域之外的神经元则支配腹侧被盖区和/或黑质致密部的内侧部分。相比之下，在伏隔核背侧更靠尾侧的部位以及尾状核 - 壳核的腹侧部分，情况则相反：强 ENK-IR 小斑块内或外的神经元分别投射至黑质致密部或黑质网状部。由于腹侧纹状体的丘脑和皮质传入纤维也是按分区排列的，因此目前的结果表明，通过腹侧纹状体分区，来自皮质和丘脑不同组合来源的信息可能会被传递至不同的中脑靶点。腹侧纹状体 - 中脑系统到达多巴胺能细胞群A10、A9和A8的部分可能会调节几乎整个纹状体的多巴胺能输入。另一部分则可通过黑质网状部参与基底神经节的黑质 - 丘脑和黑质 - 顶盖输出通路。
