Gerfen C R, Herkenham M, Thibault J
Laboratory of Neurophysiology, National Institute of Mental Health, Bethesda, Maryland 20892.
J Neurosci. 1987 Dec;7(12):3915-34. doi: 10.1523/JNEUROSCI.07-12-03915.1987.
Mesostriatal projections, which arise from dopaminergic and non-dopaminergic neurons in the ventral tegmental area, substantia nigra, and retrorubral area, are compartmentally organized in the striatum. Anterograde axonal tract tracing with Phaseolus vulgaris-leucoagglutinin (PHA-L), combined with immunohistochemical localization of tyrosine hydroxylase (TH) and autoradiographic localization of mu-opiate receptor binding sites, shows that midbrain projections to the striatum are distributed to either the mu-opiate receptor-rich "patch" or the receptor-poor "matrix" striatal compartments. Three morphologically distinct mesostriatal afferent fiber types are labeled. The first type, type A, forms a plexus of relatively thin (0.1-0.4 micron), smooth fibers with small varicosities (0.3-0.6 micron). A second type, type B, is similar to the first in forming a plexus of fibers, but is slightly thicker (0.2-0.6 micron), with more frequent varicosities (0.4-1.0 micron) that give this fiber type a crinkled appearance. The third type, type C, constitutes a minority of striatal afferents and is characterized by its large caliber (0.4-0.7 micron) with large bulbous varicosities (1.2-2.0 micron). Projections of the ventral tegmental area (A10 cell group) are primarily dopaminergic type A fibers directed to the matrix of the ventromedial striatum, including the nucleus accumbens. The retrorubral area (A8 cell group) also provides predominantly dopaminergic type A fibers to the striatal matrix, but these are distributed dorsally. The substantia nigra contains a mixed population of neurons that project to the striatum. Some, located in the dorsal tier of the pars compacta (dorsal A9 cell group), provide dopaminergic type A fibers to the striatal matrix. Others, in the ventral tier of the pars compacta (ventral A9 cell group) and in the ventral tier of the pars reticulata (displaced A9 cells), provide dopaminergic type B fibers to the striatal patches. An additional set of substantia nigra neurons that are non-dopaminergic is the source of type C fibers to the striatal matrix. Thus, distinct dorsal and ventral sets of midbrain dopaminergic neurons project, respectively, to striatal matrix and patches, and there is a non-dopaminergic mesostriatal projection to the matrix.
中脑纹状体投射起源于腹侧被盖区、黑质和红核后区的多巴胺能和非多巴胺能神经元，在纹状体内呈分区组织。用菜豆白细胞凝集素（PHA-L）进行顺行轴突束示踪，结合酪氨酸羟化酶（TH）的免疫组织化学定位和μ-阿片受体结合位点的放射自显影定位，结果显示，中脑向纹状体的投射分布于富含μ-阿片受体的“斑块”或受体较少的“基质”纹状体分区。标记出三种形态上不同的中脑纹状体传入纤维类型。第一种类型，即A型，形成一个由相对较细（0.1 - 0.4微米）、光滑且带有小膨体（0.3 - 0.6微米）的纤维组成的神经丛。第二种类型，即B型，与第一种类型相似，也形成一个纤维神经丛，但稍粗一些（0.2 - 0.6微米），膨体更频繁（0.4 - 1.0微米），使这种纤维类型呈现出皱缩的外观。第三种类型，即C型，占纹状体传入纤维的少数，其特征是直径较大（0.4 - 0.7微米），带有大的球状膨体（1.2 - 2.0微米）。腹侧被盖区（A10细胞群）的投射主要是多巴胺能A型纤维，指向腹内侧纹状体的基质，包括伏隔核。红核后区（A8细胞群）也主要向纹状体基质提供多巴胺能A型纤维，但这些纤维分布在背侧。黑质包含投射到纹状体的混合神经元群体。一些位于致密部背层（背侧A9细胞群）的神经元，向纹状体基质提供多巴胺能A型纤维。其他位于致密部腹层（腹侧A9细胞群）和网状部腹层（移位的A9细胞）的神经元，向纹状体斑块提供多巴胺能B型纤维。黑质中另一组非多巴胺能神经元是向纹状体基质提供C型纤维的来源。因此，中脑多巴胺能神经元明显分为背侧和腹侧两组，分别投射到纹状体基质和斑块，并且存在一条向基质的非多巴胺能中脑纹状体投射。
